Filed pursuant to Rule 424(b)(5)

Registration No. 333-251061

PROSPECTUS SUPPLEMENT

(To Prospectus dated December 9, 2020)

14,320,000 Shares of Common Stock

Warrants to Purchase up to 14,320,000 Shares of Common Stock

We are offering 14,320,000 shares of common stock and warrants to purchase up to 14,320,000 shares of common stock. The common stock and warrants will be sold in combination, with each share of common stock accompanied by a warrant to purchase one share of common stock. The combined purchase price for each share of common stock and accompanying warrant is $2.095.

The warrants will have an exercise price of $1.97 per share of common stock, will be exercisable upon issuance and will expire five years from the date of issuance. The shares of common stock and the warrants are immediately separable and will be issued separately, but must be purchased together in this offering. This prospectus supplement also relates to the offering of the shares of our common stock issuable upon the exercise of the warrants.

We engaged Piper Sandler & Co. to act as our exclusive placement agent, or the Placement Agent, in connection with this offering. The Placement Agent is not purchasing the securities offered by us in this offering and is not required to arrange the purchase or sale of any specific number or dollar amount of securities, but will use its reasonable best efforts to arrange for the sale of the securities offered.

Our common stock is listed on the Nasdaq Global Market under the symbol “GRTX”. On February 14, 2023, the last reported sale price of our common stock on the Nasdaq Global Market was $1.97 per share. There is no established trading market for the warrants and we do not expect a market to develop. In addition, we do not intend to list the warrants on any securities exchange or automated quotation system.

We are an “emerging growth company” under the federal securities laws and are subject to reduced public company disclosure standards. See “Prospectus Summary—Implications of Being an Emerging Growth Company.”

Investing in the common stock and warrants involves risks that are described in the “Risk Factors” section beginning on page S-5 of this prospectus supplement.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement is truthful or complete. Any representation to the contrary is a criminal offense.

Delivery of the shares of common stock and the warrants to purchase common stock will be made on or about February 17, 2023.

Sole Placement Agent

Piper Sandler

The date of this prospectus supplement is February 15, 2023

TABLE OF CONTENTS

PROSPECTUS SUPPLEMENT

PROSPECTUS

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document is part of the registration statement that we filed with the Securities and Exchange Commission, or the SEC, using a “shelf” registration process and consists of two parts. The first part is this prospectus supplement, including the documents incorporated by reference herein, which describes the specific terms of this offering. The second part, the accompanying prospectus, including the documents incorporated by reference therein, gives more general information, some of which may not apply to this offering. Generally, when we refer to the “prospectus”, we are referring to both parts combined. This prospectus supplement may add to, update or change information in the accompanying base prospectus and the documents incorporated by reference into this prospectus supplement or the accompanying prospectus.

If information in this prospectus supplement is inconsistent with the accompanying base prospectus or with any document incorporated by reference herein or therein that was filed with the SEC before the date of this prospectus supplement, you should rely on this prospectus supplement. This prospectus supplement, the accompanying base prospectus and the documents incorporated by reference into each include important information about us, the securities being offered and other information you should know before investing in our securities. You should also read and consider information in the documents we have referred you to in the sections of this prospectus supplement entitled “Where You Can Find More Information” and “Incorporation by Reference” and the accompanying base prospectus entitled “Where You Can Find More Information” and “Incorporation by Reference”.

We further note that the representations, warranties and covenants made by us in any agreement that is filed as an exhibit to any document that is incorporated by reference herein were made solely for the benefit of the parties to such agreement, including, in some cases, for the purpose of allocating risk among the parties to such agreements, and should not be deemed to be a representation, warranty or covenant to you. Moreover, such representations, warranties and covenants were accurate only as of the date when made. Accordingly, such representations, warranties and covenants should not be relied on as accurately representing the current state of our affairs.

We have not, and the Placement Agent has not, authorized anyone to provide you with information other than that contained or incorporated by reference in this prospectus supplement, the accompanying base prospectus and any free writing prospectus. We are not, and the Placement Agent is not, making an offer to sell or soliciting any offer to buy these securities in any jurisdiction where the offer or sale is not permitted or in which the person making that offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation. You should assume that the information appearing in this prospectus supplement, the accompanying base prospectus, the documents incorporated by reference herein and therein and any free writing prospectus that we have authorized for use in connection with this offering is accurate only as of the date of those respective documents. Our business, financial condition, results of operations and prospects may have changed since those dates. You should read this prospectus supplement, the accompanying base prospectus, the documents incorporated by reference herein and therein and any free writing prospectus that we have authorized for use in connection with this offering in their entirety before making an investment decision.

Before buying any of the common stock or warrants to purchase common stock that we are offering, we urge you to carefully read this prospectus supplement, the accompanying base prospectus and all of the information incorporated by reference herein and therein, as well as the additional information described under the heading “Where You Can Find More Information; Incorporation by Reference.” These documents contain important information that you should consider when making your investment decision.

We are not making offers to sell shares of our securities or soliciting offers to purchase shares of our securities in any jurisdiction in which such an offer or solicitation is not authorized or in which the person making such offer or solicitation is not qualified to do so or to anyone to whom it is unlawful to make an offer or solicitation.

When we refer to “Galera,” “we,” “our” and “us” in this prospectus supplement, we mean Galera Therapeutics, Inc. or its consolidated subsidiaries, unless otherwise specified. When we refer to “you,” we mean the holders of our securities.

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This prospectus supplement includes our trademarks and trade names, including, without limitation, GALERA, GALERA THERAPEUTICS and our logo, which are our property and are protected under applicable intellectual property laws. This prospectus supplement also contains trademarks, trade names and service marks of other companies, which are the property of their respective owners. Solely for convenience, trademarks, trade names and service marks referred to in this prospectus supplement may appear without the ^®, ^™ or SM symbols, but such references are not intended to indicate, in any way, that we or the applicable owner will not assert, to the fullest extent permitted under applicable law, our or its rights or the right of any applicable licensor to these trademarks, trade names and service marks. We do not intend our use or display of other parties’ trademarks, trade names or service marks to imply, and such use or display should not be construed to imply, a relationship with, or endorsement or sponsorship of us by, these other parties.

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WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE

Available Information

We file reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy and information statements and other information about issuers, such as us, who file electronically with the SEC. The address of that website is www.sec.gov. Our website address is www.galeratx.com. The information on our website, however, is not, and shall not be deemed to be, a part of this prospectus supplement.

This prospectus supplement and the accompanying base prospectus are part of a registration statement that we filed with the SEC, and do not contain all of the information in the registration statement. The full registration statement may be obtained from the SEC or us, as provided below. Documents establishing the terms of the offered securities are or may be filed as exhibits to the registration statement. Statements in this prospectus supplement or the accompanying base prospectus about these documents are summaries, and each such statement is qualified in all respects by reference to the document to which it refers. You should refer to the actual documents for a more complete description of the relevant matters. You may inspect a copy of the registration statement through the SEC’s website, as provided above.

Incorporation by Reference

The SEC’s rules allow us to “incorporate by reference” information in this prospectus supplement, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus supplement, and subsequent information that we file with the SEC will automatically update and supersede that information. Any statement contained in a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this prospectus supplement to the extent that a statement contained in this prospectus supplement or a subsequently filed document incorporated by reference modifies or replaces that statement.

This prospectus supplement incorporates by reference the documents set forth below that have previously been filed with the SEC (other than those documents or the portions of those documents not deemed to be filed):

All reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, or the Exchange Act, prior to the termination of this offering, including all such documents we may file with the SEC after the date of the initial registration statement of which this prospectus supplement is a part and prior to the effectiveness of the registration statement, will also be incorporated by reference in this prospectus supplement and deemed to be part of this prospectus supplement

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from the date of the filing of such reports and documents. We are not, however, incorporating by reference any documents or portions thereof, whether specifically listed above or filed in the future, that are not deemed “filed” with the SEC, including our stock performance graph or any information furnished pursuant to Items 2.02 or 7.01 of Form 8-K or related exhibits furnished pursuant to Item 9.01 of Form 8-K.

You may request a free copy of any of the documents incorporated by reference in this prospectus supplement by writing or telephoning us at the following address:

GALERA THERAPEUTICS, INC.

2 W. LIBERTY BLVD #100

MALVERN, PENNSYLVANIA 19355

(610) 725-1500

Exhibits to the filings will not be sent, however, unless those exhibits have specifically been incorporated by reference in this prospectus supplement.

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RISK FACTORS

Investment in the securities offered pursuant to this prospectus supplement and the accompanying base prospectus involves risks. You should carefully consider the risk factors described below and in our SEC filings incorporated by reference in this prospectus supplement, any amendment or update thereto reflected in subsequent filings with the SEC, including in our Annual Reports on Form 10-K and Quarterly Reports on Form 10-Q, and all other information contained or incorporated by reference in this prospectus supplement. The occurrence of any of these risks might cause you to lose all or part of your investment.

If you purchase shares of our common stock and accompanying warrants sold in this offering, you will experience immediate and substantial dilution in the net tangible book value of your shares.

The public offering price of shares of our common stock and accompanying warrants being offered hereby is higher than the net tangible book deficit per share of our outstanding common stock prior to this offering. Therefore, if you purchase securities in this offering, you will pay an effective price per share of common stock that exceeds our as adjusted net tangible book deficit per share after giving effect to this offering. Based on a public offering price of $2.095 per share and accompanying warrant, you will experience immediate dilution of $3.87 per share (and assuming no exercise of the warrants offered hereby and that such warrants are classified and accounted for as stockholders’ equity), representing the difference between our as adjusted net tangible book deficit per share as of September 30, 2022 after giving effect to this offering. See the section entitled “Dilution” for a more detailed description.

In the event the warrants are exercised, you will experience additional dilution. To the extent that any options or warrants are exercised, any new equity awards are issued under our equity incentive plans, or we otherwise issue additional shares of common stock in the future (including shares issued in connection with strategic and other transactions), you will experience further dilution. In addition, we may choose to raise additional capital due to market conditions or strategic considerations, even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities could result in further dilution to our stockholders.

We have broad discretion in the use of the net proceeds from this offering and may not use them effectively.

Our management will have broad discretion in the application of the net proceeds from this offering, including for any of the purposes described in the section entitled “Use of Proceeds,” and you will not have the opportunity as part of your investment decision to assess whether the net proceeds are being used appropriately. Because of the number and variability of factors that will determine our use of the net proceeds from this offering, their ultimate use may vary substantially from their currently intended use. Our management might not apply our net proceeds in ways that ultimately increase the value of your investment. If we do not apply the net proceeds from this offering in ways that enhance stockholder value, we may fail to achieve expected financial results, which could cause our stock price to decline.

Future sales or issuances of our common stock in the public markets, or the perception of such sales, could depress the trading price of our common stock.

The sale of a substantial number of shares of our common stock or other equity-related securities in the public markets, or the perception that such sales could occur, could depress the market price of our common stock and impair our ability to raise capital through the sale of additional equity securities. We may sell large quantities of our common stock at any time pursuant to our existing sales agreement in an “at the market” offering. We cannot predict the effect that future sales of common stock or other equity-related securities would have on the market price of our common stock.

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There is no public market for the warrants being offered hereby.

There is no established public trading market for the warrants being offered in this offering, and we do not expect a market to develop. In addition, we do not intend to apply to list the warrants on any national securities exchange or other nationally recognized trading system, including the Nasdaq Capital Market. Without an active market, the liquidity of the warrants will be limited.

Except as otherwise provided in the warrants, holders of each of the warrants purchased in this offering will have no rights as common stockholders until such holders exercise their warrants and acquire our common stock.

Until holders of warrants acquire shares of our common stock upon exercise thereof, except as otherwise provided in each of the warrants, such holders will have no rights with respect to the shares of our common stock underlying such warrants. Upon exercise of the warrants, the holders will be entitled to exercise the rights of a common stockholder only as to matters for which the record date occurs after the exercise date.

We may not receive any additional funds upon the exercise of the warrants.

The warrants may be exercised by way of a cashless exercise, meaning that the holder may not pay a cash purchase price upon exercise, but instead would receive upon such exercise the net number of shares of our common stock determined according to the formula set forth in the applicable warrants. Accordingly, we may not receive any additional funds upon the exercise of the warrants.

Provisions of the warrants could discourage an acquisition of us by a third party.

Certain provisions of the warrants could make it more difficult or expensive for a third party to acquire us. The warrants prohibit us from engaging in certain transactions constituting “fundamental transactions” unless, among other things, the surviving entity assumes our obligations under the warrants. These and other provisions of the warrants offered by this prospectus could prevent or deter a third party from acquiring us even where the acquisition could be beneficial to you.

The warrants issued in this offering may not have any value.

The warrants offered hereby have an exercise price of $1.97 per share, are immediately exercisable and will expire on the fifth anniversary of the date of issuance. In the event our common stock price does not exceed the exercise price of the warrants during the period when the warrants are exercisable, the warrants may not have any value.

We may not have the ability to repurchase the warrants.

Under certain circumstances, if a fundamental transaction (as defined in the warrant) occurs, holders of the warrants may require us to repurchase the remaining unexercised portion of such warrants for an amount of cash equal to the value of the warrant as determined in accordance with the Black Scholes option pricing model and the terms of the warrants. Our ability to repurchase the warrants depends on our ability to generate significant cash flow in the future. To some extent, this is subject to general economic, financial, competitive, and regulatory factors and other factors that are beyond our control. We cannot assure you that we will maintain sufficient cash reserves or that our business will generate significant cash flow from operations at levels sufficient to permit us to repurchase the warrants.

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CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus supplement, the accompanying base prospectus and the documents incorporated by reference herein and therein and any free writing prospectus that we have authorized for use in connection with this offering may contain forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. All statements other than statements of historical fact, including without limitation statements regarding our plans to develop and commercialize our product candidates, the timing of our ongoing or planned clinical trials, the timing of and our ability to obtain and maintain regulatory approvals, the clinical utility of our product candidates, our commercialization, manufacturing capabilities and strategy, our expectations about the willingness of healthcare professionals to use our product candidates, the sufficiency of our cash, cash equivalents and short-term investments and our ability to raise additional capital to fund our operations, our plans to mitigate the risk that we are unable to continue as a going concern, the anticipated impact of the COVID-19 pandemic and general economic conditions on our business, and the plans and objectives of management for future operations, capital needs, and capital expenditures are forward-looking statements.

The forward-looking statements are only predictions and are based largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. These forward-looking statements speak only as of the date of this prospectus supplement and are subject to a number of known and unknown risks, uncertainties and assumptions that could cause actual results to differ materially from those projected in the forward-looking statements, including, but not limited to, the following: our limited operating history; anticipating continued losses for the foreseeable future; substantial doubt regarding our ability to continue as a going concern; needing substantial funding and the ability to raise capital; our dependence on avasopasem manganese (avasopasem, or GC4419) and our other product candidates; uncertainties inherent in the conduct of clinical trials; difficulties or delays enrolling patients in clinical trials; the FDA’s acceptance of data from clinical trials outside the United States; undesirable side effects from our product candidates; risks relating to the regulatory approval process; failure to capitalize on more profitable product candidates or indications; ability to receive and/or maintain Breakthrough Therapy Designation or Fast Track Designation for product candidates; failure to obtain regulatory approval of product candidates in the United States or other jurisdictions; ongoing regulatory obligations and continued regulatory review; risks related to commercialization; risks related to competition; ability to retain key employees and manage growth; risks related to intellectual property; inability to maintain collaborations or the failure of these collaborations; our reliance on third parties; the possibility of system failures or security breaches; liability related to the privacy of health information obtained from clinical trials and product liability lawsuits; unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives; environmental, health and safety laws and regulations; the impact of the COVID-19 pandemic on our business and operations, including clinical trials, and general economic conditions; risks related to ownership of our common stock; significant costs as a result of operating as a public company; and those described under the sections in our Annual Report on Form 10-K for the year ended December 31, 2021 and our Quarterly Reports on Form 10-Q entitled “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations.”

This prospectus supplement, the accompanying base prospectus and the documents incorporated by reference herein and therein and any free writing prospectus may also contain estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. In addition, projections, assumptions and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncertainty.

Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these

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forward-looking statements as predictions of future events. Moreover, we operate in an evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained in this prospectus supplement, the accompanying base prospectus and the documents incorporated by reference herein and therein and any free writing prospectus, whether as a result of any new information, future events, changed circumstances or otherwise.

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USE OF PROCEEDS

We expect to receive net proceeds of approximately $27.7 million from this offering, after deducting placement agent fees and estimated offering expenses payable by us. This estimate excludes the proceeds, if any, from the exercise of the warrants sold in this offering. We cannot predict when or if the warrants will be exercised. It is possible that the warrants may expire and may never be exercised.

We intend to use the net proceeds from this offering to fund pre-commercialization activities related to avasopasem, advance the development of avasopasem and rucosopasem, and for working capital and other general corporate purposes.

Based on the planned use of proceeds, we believe that the net proceeds from this offering and our existing cash and cash equivalents and short term investments will be sufficient to enable us to fund our operating expenses and capital expenditure requirements into the fourth quarter of 2023. We have based this estimate on assumptions that may prove to be incorrect, and we could utilize our available capital resources sooner than we currently expect. The amounts and timing of our actual expenditures will depend on numerous factors, including the progress of our clinical trials and other development efforts and other factors described under “Risk Factors” in this prospectus supplement, the accompanying base prospectus and the documents incorporated by reference herein and therein, as well as the amount of cash used in our operations. We may find it necessary or advisable to use the net proceeds for other purposes, and we will have broad discretion in the application of the net proceeds from this offering.

Pending the use of the net proceeds described above, we plan to invest the net proceeds from this offering in a variety of capital preservation investments, including short- and intermediate-term, interest-bearing obligations, investment-grade instruments, certificates of deposit or direct or guaranteed obligations of the U.S. government.

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DIVIDEND POLICY

We have never declared or paid any dividends on our capital stock. We currently intend to retain all available funds and any future earnings, if any, for the operation and expansion of our business and, therefore, we do not anticipate declaring or paying cash dividends in the foreseeable future. The payment of dividends, if any, will be at the discretion of our board of directors and will depend on our results of operations, capital requirements, financial condition, prospects, contractual arrangements, any limitations on payment of dividends present in our future debt agreements, and other factors that our board of directors may deem relevant. Our ability to pay cash dividends on our capital stock in the future may also be limited by the terms of any preferred securities we may issue or agreements governing any additional indebtedness we may incur.

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DILUTION

If you invest in our common stock and accompanying warrants in this offering, your ownership interest will be diluted to the extent of the difference between the price per share of our common stock and accompanying warrant in this offering and the as adjusted net tangible book deficit per share of our common stock immediately after this offering.

Our historical net tangible book deficit of our common stock as of September 30, 2022 was approximately $(100.7) million, or $(3.75) per share based upon 26,831,589 shares outstanding. Net tangible book deficit per share is equal to our total tangible assets, less our total liabilities, divided by the total number of shares outstanding as of September 30, 2022.

After giving effect to our issuance and sale of 14,320,000 shares of our common stock and accompanying warrants to purchase up to 14,320,000 shares of our common stock in this offering at a public offering price of $2.095 per share of common stock and accompanying warrant, and after deducting placement agent fees and estimated offering expenses payable by us (and assuming no exercise of the warrants offered hereby and that such warrants are classified and accounted for as stockholders’ equity), our as adjusted net tangible book deficit as of September 30, 2022 would have been $(73.0) million, or $(1.77) per share of common stock. This represents an immediate decrease in as adjusted net tangible book deficit of $1.98 per share of common stock to our existing stockholders and immediate dilution in as adjusted net tangible book deficit of $3.87 per share of common stock to purchasers in this offering. Dilution per share is calculated by subtracting as adjusted net tangible book deficit per share after this offering from the public offering price per share of common stock and accompanying warrant.

The following table illustrates this per share dilution:

After giving effect to the exercise of the warrants to purchase 14,320,000 shares of common stock in full at an exercise price of $1.97 per share, our as adjusted net tangible book deficit per share after this offering would be $(0.81), representing an immediate increase in as adjusted net tangible book deficit per share of $2.94 to existing stockholders and immediate dilution in as adjusted net tangible book deficit per share of $2.91 to purchasers in this offering.

The above discussion and table is based on 26,831,589 shares of common stock outstanding as of September 30, 2022, and excludes:

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Unless otherwise stated, the above discussion and table does not reflect:

To the extent that we sell additional shares of common stock pursuant to our Sales Agreement, any outstanding options or warrants are exercised or we otherwise issue additional shares of common stock or warrants in the future, there will be further dilution to new investors. In addition, we may choose to raise additional capital due to market conditions or strategic considerations even if we believe we have sufficient funds for our current or future operating plans. To the extent that additional capital is raised through the sale of equity or convertible debt securities, the issuance of these securities may result in further dilution to our stockholders.

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DESCRIPTION OF THE SECURITIES WE ARE OFFERING

The following is a brief summary of certain terms and conditions of our common stock and the warrants being offered in this offering. The following description is subject in all respects to the provisions contained in the form of warrant. This prospectus supplement also relates to the offering of the shares of our common stock issuable upon exercise of the warrants.

Common Stock

The material terms and provisions of our common stock are described under the caption “Description of Capital Stock” of the accompanying prospectus.

Our common stock is listed on The Nasdaq Global Market under the symbol “GRTX”.

Our transfer agent for our common stock is American Stock Transfer & Trust Company, LLC.

Warrants

The following summary of certain terms and provisions of the warrants is not complete and is subject to, and qualified in its entirety by, the provisions of the form of warrant. Prospective investors should carefully review the terms and provisions of the form of warrant for a complete description of the terms and conditions of the warrants.

Form. The form of warrant will be filed as an exhibit to our Current Report on Form 8-K in connection with this offering. The warrants will be issued in certificated form.

Exercisability. The warrants will be exercisable immediately and at any time until February 17, 2028. The warrants will be exercisable, at the option of each holder, in whole or in part by delivering to us a duly executed exercise notice and, at any time a registration statement registering the issuance of the shares of common stock underlying the warrants under the Securities Act is effective and available for the issuance of such shares, or an exemption from registration under the Securities Act is available for the issuance of such shares, by payment in full in immediately available funds for the number of shares of common stock purchased upon such exercise. No fractional shares of common stock will be issued in connection with the exercise of the warrants.

Exercise Limitation. A holder will not have the right to exercise any portion of the warrant if the holder (together with its affiliates) would beneficially own in excess of 4.99% of the number of shares of our common stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the warrants. However, any holder may increase or decrease such percentage to any other percentage not in excess of 9.99%, provided that any increase in such percentage shall not be effective until 61 days following notice from the holder to us.

Exercise Price. The warrants are exercisable for an aggregate of 14,320,000 shares of our common stock, at an initial exercise price of $1.97 per share of common stock. The initial exercise price and number of shares of common stock issuable upon exercise of the warrants will proportionally adjust in the event of certain stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting our common stock.

Fundamental Transaction. In the event we consummate a merger or consolidation with or into another person or other reorganization event in which our common stock are converted or exchanged for securities, cash or other property, or we sell, lease, license, assign, transfer, convey or otherwise dispose of all or substantially all of our assets or we or another person acquire 50% or more of our outstanding shares of common stock, then following such event, the holders of the warrants will be entitled to receive upon exercise of such warrants the

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same kind and amount of securities, cash or property which the holders would have received had they exercised their warrants immediately prior to such fundamental transaction. Any successor to us or surviving entity shall assume the obligations under the warrants. Additionally, as more fully described in the warrants, in the event of certain fundamental transactions, the holders of the warrants will be entitled to receive consideration in an amount equal to the Black Scholes value of the warrants on the date of consummation of such transaction.

Exchange Listing. There is no established public trading market for the warrants, and we do not expect a market to develop. In addition, we do not intend to list the warrants on any securities exchange or nationally recognized trading system. Without an active trading market, the liquidity of the warrants will be limited.

Right as a Stockholder. Except as otherwise provided in the warrants or by virtue of such holder’s ownership of shares of our common stock, the holders of the warrants do not have the rights or privileges of holders of our common stock, including any voting rights, until they exercise their warrants.

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PLAN OF DISTRIBUTION

Piper Sandler & Co., as placement agent, has agreed to act as our placement agent in connection with this offering, subject to the terms and conditions of the placement agency agreement dated February 15, 2023, entered into by and between the Company and the placement agent. The placement agent will use its reasonable best efforts to arrange for the sale of the securities offered by this prospectus supplement. The placement agent is not obligated to purchase any of the securities offered or otherwise provide any financing. We have entered into a securities purchase agreement directly with the investors in connection with this offering, pursuant to which, subject to certain conditions, we will sell to the investors an aggregate of 14,320,000 shares of common stock and warrants to purchase up to 14,320,000 shares of common stock. There is no market through which the warrants may be sold and the investors may not be able to resell the warrants purchased under this prospectus supplement. The securities purchase agreement contains customary representations, warranties and covenants.

We will deliver the shares of common stock offered pursuant to this prospectus supplement to the investors electronically upon receipt of investor funds for the purchase of such shares. The warrants will be issued in certificated form. We expect to deliver the shares of our common stock and warrants being offered pursuant to this prospectus supplement on or about February 17, 2023, subject to customary closing conditions.

This is a summary of the material provisions of the placement agency agreement and securities purchase agreement and does not purport to be a complete statement of their terms and conditions. A copy of the placement agency agreement and the form of securities purchase agreement with the investors will be filed with the SEC and are incorporated by reference into the registration statement of which this prospectus supplement forms a part.

Fees and Expenses

We have agreed to pay the placement agent a cash fee of 6.0% of the aggregate gross proceeds of this offering paid to us at closing. We have also agreed to reimburse the placement agents for certain of their expenses related to this offering in an amount not to exceed $75,000.

The terms of this offering were subject to market conditions and negotiations between us and the investors. The factors considered in determining the price included the recent market price of our common stock, the general condition of the securities market at the time of this offering, the history of, and the prospects, for the industry in which we compete, our past and present operations, and our prospects for future revenues.

The placement agent may be deemed to be an underwriter within the meaning of Section 2(a)(11) of the Securities Act, and any fees or commissions received by them and any profit realized on the resale of the securities sold by them while acting as principal might be deemed to be underwriting discounts or commissions under the Securities Act. As an underwriter, the placement agent would be required to comply with the requirements of the Securities Act and the Exchange Act, including, without limitation, Rule 10b-5 and Regulation M under the Exchange Act.

These rules and regulations may limit the timing of purchases and sales of our securities by the placement agent. Under these rules and regulations, the placement agent:

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We have agreed to indemnify the placement agent and certain other persons against certain liabilities, including civil liabilities under the Securities Act and the Exchange Act and to contribute to payments that the placement agents may be required to make in respect of those liabilities.

From time to time, the placement agent has provided and may provide in the future, various financial advisory, investment banking and other services to us in the ordinary course of business, for which they have received and may continue to receive customary fees and commissions.

No Sales of Similar Securities

Our executive officers and directors have entered into lock-up agreements with us. Under these agreements, each of these persons may not, subject to certain exceptions, offer, sell, contract to sell, lend, hypothecate, pledge or otherwise dispose of (or enter into any transaction which is designed to, or might reasonably be expected to, result in such disposition) directly or indirectly, or establish or increase a put equivalent position or liquidate or decrease a call equivalent position within the meaning of Section 16 of the Exchange Act with respect to, shares of our common stock or securities convertible, exchangeable or exercisable into, shares of our common stock. These restrictions will be in effect for a period of 90 days after the closing of this offering.

Listing

Our common stock is listed on The Nasdaq Global Market under the trading symbol “GRTX”.

We do not intend to apply for listing of the warrants on any securities exchange or other nationally recognized trading system.

The placement agent may distribute this prospectus supplement and the accompanying prospectus electronically.

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MATERIAL U.S. FEDERAL INCOME TAX CONSEQUENCES TO HOLDERS OF OUR COMMON STOCK AND WARRANTS

The following discussion is a summary of the U.S. federal income tax considerations generally applicable to the acquisition, ownership and disposition of our common stock and warrants, which we refer to collectively as our securities. This summary is based upon the Internal Revenue Code of 1986, as amended (“the Code”), the Treasury regulations promulgated thereunder, and administrative pronouncements, judicial decisions and, in each case as of the date of this prospectus supplement, all of which are subject to change or differing interpretations, possibly with retroactive effect. This summary does not discuss all aspects of U.S. federal income taxation that may be important to particular investors in light of their individual circumstances, including investors subject to special tax rules (e.g., financial institutions, insurance companies, broker-dealers, partnerships (including entities or arrangements treated as partnerships or other pass-through entities for U.S. federal income tax purposes) and their partners, tax-exempt organizations (including, but not limited to, private foundations), taxpayers that have elected mark-to-market accounting, S corporations, regulated investment companies, real estate investment trusts, investors that will hold our common stock or warrants as part of a straddle, hedge, conversion, or other integrated transaction for U.S. federal income tax purposes, U.S. expatriates and certain former U.S. citizens or long-term residents, or investors that have a functional currency other than the U.S. dollar), all of whom may be subject to tax rules that differ materially from those summarized below. In addition, this summary does not discuss other U.S. federal tax considerations (e.g., estate or gift tax), any state, local, or non-U.S. tax considerations or the Medicare contribution tax or alternative minimum tax. In addition, this summary is limited to investors that will hold our securities as “capital assets” (generally, property held for investment) under the Code and that acquired the securities pursuant to this offering (or, in the case of our common stock, upon exercise of warrants so acquired). No ruling from the U.S. Internal Revenue Service, (the “IRS”) has been or will be sought regarding any matter discussed herein. No assurance can be given that the IRS would not assert, or that a court would not sustain, a position contrary to any of the tax statements and conclusions set forth below.

For purposes of this summary, a “U.S. Holder” is a beneficial holder of our securities who or that, for U.S. federal income tax purposes, is:

A “non-U.S. Holder” is a beneficial holder of our securities who or that is neither a U.S. Holder nor a partnership or other pass-through entity or arrangement for U.S. federal income tax purposes.

If an entity or arrangement treated as a partnership or other pass-through entity for U.S. federal income tax purposes holds our securities, the tax treatment of a partner, member or other beneficial owner in such entity or arrangement will generally depend upon the status of the partner, member or other beneficial owner, the activities of the entity and certain determinations made at the partner, member or other beneficial owner level. If you are a partner, member or other beneficial owner of an entity or arrangement treated as a partnership or other pass-through entity for U.S. federal income tax purposes holding our securities, you are urged to consult with your tax advisor regarding the tax consequences of the ownership and disposition of our securities.

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THIS DISCUSSION OF U.S. FEDERAL INCOME TAX CONSIDERATIONS IS FOR GENERAL INFORMATION PURPOSES ONLY AND IS NOT TAX ADVICE. WE URGE PROSPECTIVE HOLDERS TO CONSULT WITH THEIR TAX ADVISORS CONCERNING THE U.S. FEDERAL INCOME TAX CONSEQUENCES TO THEM OF ACQUIRING, OWNING AND DISPOSING OF OUR SECURITIES, AS WELL AS THE APPLICATION OF ANY U.S. FEDERAL ESTATE AND GIFT TAX LAWS AND ANY STATE, LOCAL AND NON-U.S. TAX LAWS AND TAX TREATIES.

Allocation of Purchase Price

Each share of common stock and accompanying warrant is expected to be treated for U.S. federal income tax purposes as an investment unit consisting of one share of our common stock and a warrant to purchase one share of our common stock. For U.S. federal income tax purposes, each holder must allocate the purchase price paid by such holder fora share of our common stock and accompanying warrant based on the relative fair market value of each at the time of issuance. Under U.S. federal income tax law, each investor must make his or her own determination of such value based on all the relevant facts and circumstances. Therefore, we strongly urge each investor to consult with his or her tax advisor regarding the determination of value for these purposes. The price allocated to each share of our common stock and each warrant should be the stockholder’s initial tax basis in such share or warrant, as the case may be.

A holder’s purchase price allocation is not binding on the IRS or the courts. Each prospective investor is urged to consult with its tax advisors regarding the U.S. federal, state, local and non-U.S. tax consequences of an investment in our securities.

U.S. Holders

Taxation of Distributions with Respect to Our Common Stock

As described in the section entitled “Dividend Policy,” we do not anticipate declaring or paying any future distributions. However, if we do make distributions in cash or other property to U.S. Holders of our common stock, such distributions will constitute dividends for U.S. federal income tax purposes to the extent paid from our current or accumulated earnings and profits, as determined under U.S. federal income tax principles. Distributions in excess of current and accumulated earnings and profits will constitute a return of capital to the extent of a U.S. Holder’s adjusted tax basis in our common stock that will be applied against and reduce (but not below zero) such tax basis. Any remaining excess will be treated as gain realized on the sale or other disposition of the common stock and will be treated as described under “U.S. Holders—Gain or Loss on Sale, Taxable Exchange or Other Taxable Disposition of Our Common Stock and Warrants,” below.

Dividends we pay to a U.S. Holder that is a taxable corporation generally will qualify for the dividends received deduction if the requisite holding period is satisfied. With certain exceptions (including, but not limited to, dividends treated as investment income for purposes of investment interest deduction limitations), and provided certain holding period requirements are met, dividends we pay to a non-corporate U.S. Holder will generally constitute “qualified dividends” that will be subject to U.S. federal income tax at preferential long-term capital gains rates. U.S. Holders should consult with their tax advisors regarding the availability of the dividends received deduction or the lower preferential rate for qualified dividend income, as the case may be, for any dividends paid with respect to our common stock.

Gain or Loss on Sale, Taxable Exchange or Other Taxable Disposition of Our Common Stock and Warrants

Subject to the discussions below regarding the exercise of warrants, a U.S. Holder will recognize gain or loss on the sale (including in an open market transaction), taxable exchange or other taxable disposition of our common stock or warrants. Any such gain or loss will be capital gain or loss, and will generally be long-term capital gain or loss if the U.S. Holder’s holding period for the common stock or warrants so disposed of (as applicable) exceeds one year. Long-term capital gains recognized by non-corporate U.S. Holders will generally be eligible to be taxed at reduced rates.

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The amount of gain or loss recognized will generally be equal to the difference between (1) the sum of the amount of cash and the fair market value of any property received in such disposition and (2) the U.S. Holder’s adjusted tax basis in its common stock or warrants so disposed of. A U.S. Holder’s adjusted tax basis in its common stock or warrants will generally equal the U.S. Holder’s acquisition cost (that is, as discussed above, the portion of the purchase price allocated to a share of our common stock or one warrant or, as discussed below, the U.S. Holder’s initial basis for our common stock received upon exercise of a warrant) less, in the case of a share of our common stock, any prior distributions treated as a return of capital, and in the case of warrants, increased by any constructive distributions treated as dividends. The deductibility of capital losses is subject to limitations.

Exercise of a Warrant

Except as discussed below with respect to cash received in lieu of a fractional share and the cashless exercise of a warrant, a U.S. Holder will not recognize gain or loss upon the exercise of a warrant. The U.S. Holder’s tax basis in the share of our common stock received upon exercise of the warrant (including any fractional share deemed received) will be an amount equal to the sum of the U.S. Holder’s adjusted tax basis in the warrant (i.e., generally the portion of the U.S. Holder’s purchase price that is allocated to the warrant, as described above, under “—Allocation of Purchase Price”) and the exercise price of such warrant. It is unclear whether a U.S. Holder’s holding period for the common stock received will commence on the date of exercise of the warrant or the day following the date of exercise of the warrant; however, in either case the holding period will not include the period during which the U.S. Holder held the warrants.

Cash received in lieu of a fractional share of our common stock upon the exercise of a warrant should be treated as a payment in exchange for the fractional share of our common stock. Accordingly, the receipt of cash in lieu of a fractional share of our common stock should generally result in capital gain or loss, which would be equal to the difference between the amount of cash received in lieu of a fractional share and the portion of the U.S. Holder’s tax basis in our common stock received that is allocable to the fractional share.

The tax consequences of a cashless exercise of a warrant are not clear under current tax law. A cashless exercise may be nontaxable, either because the exercise is not a realization event or, if it is treated as a realization event, because the exercise is treated as a recapitalization for U.S. federal income tax purposes. In either situation, a U.S. Holder’s initial tax basis in the common stock received (including any fractional share deemed received) would generally equal the holder’s adjusted tax basis in the warrant. If the cashless exercise were treated as not being a realization event, it is unclear whether a U.S. Holder’s holding period for the common stock received would commence on the date of exercise of the warrant or the day following the date of exercise of the warrant; however, in either case, the holding period would not include the period during which the U.S. Holder held the warrant. If, however, the cashless exercise were treated as a recapitalization, the holding period of the common stock received would include the holding period of the warrant.

It is also possible that a cashless exercise could be treated in whole or in part as a taxable exchange in which gain or loss would be recognized. For example, a portion of the warrants to be exercised on a cashless basis could, for U.S. federal income tax purposes, be deemed to have been surrendered in payment of the exercise price of the remaining portion of such warrants, which would be deemed to be exercised. In such event, a U.S. Holder could be deemed to have surrendered a number of warrants having an aggregate fair market value equal to the exercise price for the total number of warrants deemed exercised. The U.S. Holder would recognize capital gain or loss in an amount equal to the difference between the fair market value of the warrants deemed surrendered and the U.S. Holder’s tax basis in such warrants. Such gain or loss would be long-term or short-term depending on the U.S. Holder’s holding period in the warrants deemed surrendered. In this case, a U.S. Holder’s tax basis in the common stock received (including any fractional share deemed received) would equal the sum of the U.S. Holder’s adjusted tax basis in the warrants deemed exercised (i.e., generally the portion of the U.S. Holder’s purchase price that is allocated to such warrants, as described above, under “—Allocation of Purchase Price”) and the exercise price of such warrants. It is unclear whether a U.S. Holder’s holding period for the common stock would commence on the date of exercise of the warrant or the day following the date of exercise of the warrant; in either case, the holding period would not include the period during which the U.S. Holder held the warrant.

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Due to the absence of authority on the U.S. federal income tax treatment of a cashless exercise, including when a U.S. Holder’s holding period would commence with respect to the common stock received, there can be no assurance which, if any, of the alternative tax consequences and holding periods described above would be adopted by the IRS or a court of law. Accordingly, U.S. Holders are urged to consult with their tax advisors regarding the tax consequences of a cashless exercise.

Expiration of a Warrant

If a warrant is allowed to lapse unexercised, a U.S. Holder generally will recognize a capital loss equal to such holder’s adjusted tax basis in the warrant (i.e., generally the portion of the U.S. Holder’s purchase price that is allocated to such warrant, as described above, under “—Allocation of Purchase Price”). Such loss will generally be treated as long-term capital loss if the warrant is held by the U.S. Holder for more than one year at the time of such disposition or expiration. The deductibility of capital losses is subject to certain limitations.

Possible Constructive Distributions with Respect to Warrants

The terms of each warrant provide for an adjustment to the number of shares of our common stock for which the warrant may be exercised or to the exercise price of the warrant in certain events, as discussed in this prospectus supplement under the section entitled “Description of the Securities We Are Offering — Exercise Price”. An adjustment which has the effect of preventing dilution is generally not a taxable event. Nevertheless, a U.S. Holder of warrants may be treated as receiving a constructive distribution from us if, for example, the adjustment increases the holder’s proportionate interest in our assets or earnings and profits (e.g., through an increase in the number of shares of our common stock that would be obtained upon exercise or through a decrease in the exercise price of the warrants), including as a result of a distribution of cash or other property, such as other securities, to the holders of our common stock, or as a result of the issuance of a stock dividend to holders of our common stock, in each case which is taxable to such holders as a distribution. In addition, the failure to provide for an adjustment (or to adequately adjust) to prevent dilution may also result in a constructive distribution. Any constructive distribution received by a U.S. Holder would be subject to tax in the same manner as if such U.S. Holder received a cash distribution (as described above under “—Taxation of Distributions with Respect to Our Common Stock”) from us equal to the fair market value of such increased proportionate interest. Generally, a U.S. Holder’s adjusted tax basis in its warrant would be increased to the extent any such constructive distribution is treated as a dividend. For certain informational reporting purposes, we are required to determine the date and amount of any such constructive distributions and publicly report such information or report such information to the IRS and holders of warrants not exempt from information reporting. Proposed U.S. Treasury regulations, which we may rely on prior to the issuance of final regulations, specify how the date and amount of constructive distributions, and withholding obligations with respect thereto, are determined.

Information Reporting and Backup Withholding

Dividend payments with respect to the common stock paid, and constructive dividends with respect to a warrant deemed paid, in each case to a U.S. Holder and proceeds from the sale, exchange or other taxable disposition of our common stock and warrants by a U.S. Holder generally are subject to information reporting to the IRS and possible U.S. backup withholding, unless the U.S. Holder is an exempt recipient and certifies to such exempt status. Backup withholding may apply to such payments if a U.S. Holder fails to furnish a correct taxpayer identification number, a certification of exempt status or has been notified by the IRS that it is subject to backup withholding (and such notification has not been withdrawn). Backup withholding is not an additional tax. Amounts withheld as backup withholding may be credited against a U.S. Holder’s U.S. federal income tax liability, and such holder may obtain a refund of any excess amounts withheld under the backup withholding rules by timely filing the appropriate claim for refund with the IRS and furnishing any required information.

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Non-U.S. Holders

Taxation of Distributions with Respect to Our Common Stock

In general, any distributions (including constructive distributions, as described below under “Non-U.S. Holders—Possible Constructive Distributions with Respect to Warrants”) we make to a non-U.S. Holder with regard to our common stock, to the extent paid out of our current or accumulated earnings and profits (as determined under U.S. federal income tax principles), will constitute dividends for U.S. federal income tax purposes and, subject to the withholding requirements under FATCA (as defined below) and provided such dividends are not effectively connected with the non-U.S. Holder’s conduct of a trade or business within the United States, we (or the applicable withholding agent) will be required to withhold tax from the gross amount of the dividend at a rate of 30%, unless such non-U.S. Holder is eligible for a reduced rate of withholding tax under an applicable income tax treaty and provides proper certification of its eligibility for such reduced rate (usually on an IRS Form W-8BEN or W-8BEN-E, as applicable). In the case of any constructive dividend, it is possible that this tax would be withheld from any amount payable or distributable to a non-U.S. Holder by the applicable withholding agent, including cash distributions on other property or sale proceeds from warrants or other property subsequently paid or credited to such holder. Any distribution not constituting a dividend will be treated first as reducing (but not below zero) the non-U.S. Holder’s adjusted tax basis in its shares of our common stock and, to the extent such distribution exceeds the non-U.S. Holder’s adjusted tax basis, as gain realized from the sale or other disposition of the common stock, which will be treated as described under “Non-U.S. Holders—Gain on Sale, Exchange or Other Taxable Disposition of Our Common Stock and Warrants” below.

Dividends we pay to a non-U.S. Holder that are effectively connected with such non-U.S. Holder’s conduct of a trade or business within the United States (and, if an applicable tax treaty so requires, are attributable to a U.S. permanent establishment or fixed base maintained by the non-U.S. Holder) will generally not be subject to U.S. withholding tax, provided such non-U.S. Holder complies with certain certification and disclosure requirements (usually by providing an IRS Form W-8ECI). Instead, such dividends will generally be subject to U.S. federal income tax, net of certain deductions, at the same individual or corporate rates applicable to U.S. Holders, as relevant to the non-U.S. Holder. If the non-U.S. Holder is a corporation for U.S. federal income tax purposes, dividends that are effectively connected income may also be subject to a “branch profits tax” at a rate of 30% (or such lower rate as may be specified by an applicable income tax treaty).

A non-U.S. Holder that is eligible for a reduced rate of U.S. withholding tax under an income tax treaty may obtain a refund or credit of any excess amounts withheld by timely filing an appropriate claim for refund with the IRS.

Distributions will also be subject to the discussion below under the headings “—Information Reporting and Backup Withholding” and “—Foreign Account Tax Compliance Act.”

Exercise or Expiration of a Warrant

The characterization for U.S. federal income tax purposes of the exercise of warrants held by a non-U.S. Holder generally will correspond to the characterization described under “U.S. Holders—Exercise of a Warrant.” To the extent a cashless exercise results in a taxable exchange, the tax consequences to the non-U.S. Holder generally would be similar to those described below in “Non-U.S. Holders—Gain on Sale, Taxable Exchange or Other Taxable Disposition of Our Common Stock and Warrants.”

If a non-U.S. Holder allows a warrant to expire unexercised, such non-U.S. Holder will recognize a capital loss in an amount equal to such holder’s tax basis in the warrant. See “U.S. Holders—Expiration of a Warrant” above.

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Gain on Sale, Taxable Exchange or Other Taxable Disposition of Our Common Stock and Warrants

Subject to the discussion below under “Non-U.S. Holders—Information Reporting and Backup Withholding,” a non-U.S. Holder will generally not be subject to U.S. federal income or withholding tax in respect of gain recognized on a sale, taxable exchange or other taxable disposition of our common stock or our warrants, unless:

Unless an applicable treaty provides otherwise, gain described in the first bullet point above will be subject to tax at generally applicable U.S. federal income tax rates in the manner generally applicable to United States persons. Any gains described in the first bullet point above of a non-U.S. Holder that is a foreign corporation may also be subject to an additional “branch profits tax” at a 30% rate (or lower applicable treaty rate). Gain described in the second bullet point above will generally be subject to U.S. federal tax at a flat 30% rate (or lower applicable treaty rate).

If the third bullet point above applies to a non-U.S. Holder, gain recognized by such holder on the sale, exchange or other disposition of our common stock or warrants will be subject to U.S. federal income tax at generally applicable U.S. federal income tax rates in the manner generally applicable to United States persons. In addition, a buyer of our common stock or warrants from such holder may be required to withhold U.S. federal income tax at a rate of 15% from the gross proceeds of such disposition. We believe we currently are not, and do not anticipate becoming, a USRPHC. Because the determination of whether we are a USRPHC depends, however, on the fair market value of our U.S. real property interests relative to the fair market value of our non-U.S. real property interests and our other business assets, there can be no assurance we currently are not a USRPHC or will not become one in the future. Non-U.S. Holders are urged to consult with their tax advisors regarding the application of the USRPHC rules to their investment in the securities and the availability of any exemptions from the imposition of U.S. federal income tax (including withholding tax) in the event that the common stock and/or the warrants are treated as regularly traded on an established securities market.

Non-U.S. Holders are urged to consult with their tax advisors regarding possible eligibility for benefits under income tax treaties.

Possible Constructive Distributions with Respect to Warrants

The terms of each warrant provide for an adjustment to the number of shares of our common stock for which the warrant may be exercised or to the exercise price of the warrant in certain events, as discussed in the section of this prospectus supplement captioned “Description of the Securities We Are Offering.” An adjustment which has the effect of preventing dilution is generally not a taxable event. Nevertheless, a non-U.S. Holder of warrants may be treated as receiving a constructive distribution from us if, for example, the adjustment increases the holder’s proportionate interest in our assets or earnings and profits (e.g., through an increase in the number of shares of our common stock that would be obtained upon exercise or through a decrease in the exercise price of the warrants), including as a result of a distribution of cash or other property, such as other securities, to the holders of our common stock, or as a result of the issuance of a stock dividend to holders of our common stock, in each case which is taxable to such holders of such shares as a distribution. In addition, the failure to provide for an adjustment (or to adequately adjust) to prevent dilution may also result in a constructive distribution. Any

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constructive distribution received by a non-U.S. Holder would be subject to U.S. federal income tax (including any applicable withholding) in the same manner as if such non-U.S. Holder received a cash distribution from us equal to the fair market value of such increased proportionate interest. It is possible that any withholding tax on such a constructive distribution might be satisfied by us or the applicable withholding agent from other distributions to the non-U.S. Holder, or from proceeds subsequently paid or credited to such holder. Generally, a non-U.S. Holder’s adjusted tax basis in its warrant would be increased to the extent any such constructive distribution is treated as a dividend. For certain informational reporting purposes, we are required to determine the date and amount of any such constructive distributions and publicly report such information or report such information to the IRS and holders of warrants not exempt from information reporting. Proposed U.S. Treasury regulations, which we may rely on prior to the issuance of final regulations, specify how the date and amount of constructive distributions, and withholding obligations with respect thereto, are determined.

Information Reporting and Backup Withholding

In general, information reporting requirements will apply to payments of distributions (including constructive distributions) to non-U.S. Holders and payments of proceeds from the sale of our securities effected by or through a U.S. office of a broker to non-U.S. Holders that are not exempt recipients. We must report annually to the IRS and to each such holder the amount of dividends or other distributions we pay (or constructive distributions we are deemed to pay) to such non-U.S. Holder on our common stock and warrants and the amount of tax withheld with respect to those distributions, regardless of whether withholding is required. The IRS may make copies of the information returns reporting those dividends and amounts withheld available to the tax authorities in the country in which the non-U.S. Holder resides pursuant to the provisions of an applicable income tax treaty or exchange of information treaty.

The gross amount of distributions (including constructive distributions) and proceeds from the disposition of our common stock or warrants paid to a non-U.S. Holder that fails to provide the appropriate certification in accordance with applicable U.S. Treasury regulations generally will be subject to backup withholding at the applicable rate.

Information reporting and backup withholding are generally not required with respect to the amount of any proceeds from the sale by a non-U.S. Holder of our common stock or warrants outside the United States through a foreign office of a foreign broker that does not have certain specified connections to the United States. However, if a non-U.S. Holder sells our common stock or warrants through a U.S. broker or the U.S. office of a foreign broker, the broker will generally be required to report to the IRS the amount of proceeds paid to such holder, unless the non-U.S. Holder provides appropriate certification (usually on an IRS Form W-8BEN or W-8BEN-E, as applicable) to the broker of its status as a non-U.S. Holder or of such non-U.S. Holder’s status as an exempt recipient. In addition, for information reporting purposes, certain non-U.S. brokers with certain relationships with the United States will be treated in a manner similar to U.S. brokers.

Backup withholding is not an additional tax. The amount of any backup withholding from a payment to a non-U.S. Holder will be allowed as a credit against such holder’s U.S. federal income tax liability, if any, and may entitle such holder to a refund, provided that the required information is timely furnished to the IRS.

All non-U.S. Holders should consult with their tax advisors regarding the application of information reporting and backup withholding to them.

Foreign Account Tax Compliance Act

Sections 1471 through 1474 of the Code and the U.S. Treasury regulations and administrative guidance promulgated thereunder (commonly referred as the “Foreign Account Tax Compliance Act” or “FATCA”) generally impose withholding at a rate of 30% in certain circumstances on dividends (including constructive dividends) in respect of our securities which are held by or through certain foreign financial institutions

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(including investment funds), unless any such institution (1) enters into, and complies with, an agreement with the IRS to report, on an annual basis, information with respect to interests in, and accounts maintained by, the institution that are owned by certain U.S. persons and by certain non-U.S. entities that are wholly or partially owned by U.S. persons and to withhold on certain payments, or (2) if required under an intergovernmental agreement between the United States and an applicable foreign country, reports such information to its local tax authority, which will exchange such information with the U.S. authorities. An intergovernmental agreement between the United States and an applicable foreign country may modify these requirements. Accordingly, the entity through which our securities are held will affect the determination of whether such withholding is required. Similarly, dividends (including constructive dividends) in respect of our securities held by an investor that is a non-financial non-U.S. entity that does not qualify under certain exceptions will generally be subject to withholding at a rate of 30%, unless such entity either (1) certifies to us or the applicable withholding agent that such entity does not have any “substantial United States owners” (as defined in the Code) or (2) provides certain information regarding the entity’s direct and indirect “substantial United States owners,” which will in turn be provided to the U.S. Department of Treasury.

While withholding under FATCA would also have applied to payments of gross proceeds from the sale or other disposition of our securities, proposed Treasury regulations eliminate FATCA withholding on payments of gross proceeds entirely. Although these Treasury regulations are not final, taxpayers generally may rely on them until final Treasury regulations are issued. Prospective investors should consult with their tax advisors regarding the potential application of withholding under FATCA to their investment in our securities.

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LEGAL MATTERS

The validity of the shares of our common stock and warrants offered hereby will be passed upon for us by Latham & Watkins LLP. Cooley LLP, New York, New York is counsel to the Placement Agent in connection with this offering.

EXPERTS

The consolidated financial statements of Galera Therapeutics, Inc. as of December 31, 2021 and 2020, and for the years then ended, have been incorporated by reference herein and in the registration statement in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

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PROSPECTUS

GALERA THERAPEUTICS, INC.

$200,000,000

Common Stock

Preferred Stock

Debt Securities

Warrants

Units

We may offer and sell up to $200,000,000 in the aggregate of the securities identified above from time to time in one or more offerings. This prospectus provides you with a general description of the securities.

Each time we offer and sell securities, we will provide a supplement to this prospectus that contains specific information about the offering and the amounts, prices and terms of the securities. The supplement may also add, update or change information contained in this prospectus with respect to that offering. You should carefully read this prospectus and the applicable prospectus supplement before you invest in any of our securities.

We may offer and sell the securities described in this prospectus and any prospectus supplement to or through one or more underwriters, dealers and agents, or directly to purchasers, or through a combination of these methods. If any underwriters, dealers or agents are involved in the sale of any of the securities, their names and any applicable purchase price, fee, commission or discount arrangement between or among them will be set forth, or will be calculable from the information set forth, in the applicable prospectus supplement. See the sections of this prospectus entitled “About this Prospectus” and “Plan of Distribution” for more information. No securities may be sold without delivery of this prospectus and the applicable prospectus supplement describing the method and terms of the offering of such securities.

INVESTING IN OUR SECURITIES INVOLVES RISKS. SEE THE “RISK  FACTORS” ON PAGE 5 OF THIS PROSPECTUS AND ANY SIMILAR SECTION CONTAINED IN THE APPLICABLE PROSPECTUS SUPPLEMENT CONCERNING FACTORS YOU SHOULD CONSIDER BEFORE INVESTING IN OUR SECURITIES.

Our common stock is listed on the Nasdaq Global Market under the symbol “GRTX.” On November 30, 2020, the last reported sale price of our common stock on the Nasdaq Global Market was $10.92 per share.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or passed upon the adequacy or accuracy of this prospectus. Any representation to the contrary is a criminal offense.

The date of this prospectus is December 9, 2020.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the U.S. Securities and Exchange Commission, or the SEC, using a “shelf” registration process. By using a shelf registration statement, we may sell securities from time to time and in one or more offerings up to a total dollar amount of $200,000,000 as described in this prospectus. Each time that we offer and sell securities, we will provide a prospectus supplement to this prospectus that contains specific information about the securities being offered and sold and the specific terms of that offering. We may also authorize one or more free writing prospectuses to be provided to you that may contain material information relating to these offerings. The prospectus supplement or free writing prospectus may also add, update or change information contained in this prospectus with respect to that offering. If there is any inconsistency between the information in this prospectus and the applicable prospectus supplement or free writing prospectus, you should rely on the prospectus supplement or free writing prospectus, as applicable. Before purchasing any securities, you should carefully read both this prospectus and the applicable prospectus supplement (and any applicable free writing prospectuses), together with the additional information described under the heading “Where You Can Find More Information; Incorporation by Reference.”

We have not authorized anyone to provide you with any information or to make any representations other than those contained in this prospectus, any applicable prospectus supplement or any free writing prospectuses prepared by or on behalf of us or to which we have referred you. We take no responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. We will not make an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus and the applicable prospectus supplement to this prospectus is accurate only as of the date on its respective cover, that the information appearing in any applicable free writing prospectus is accurate only as of the date of that free writing prospectus, and that any information incorporated by reference is accurate only as of the date of the document incorporated by reference, unless we indicate otherwise. Our business, financial condition, results of operations and prospects may have changed since those dates. This prospectus incorporates by reference, and any prospectus supplement or free writing prospectus may contain and incorporate by reference, market data and industry statistics and forecasts that are based on independent industry publications and other publicly available information. Although we believe these sources are reliable, we do not guarantee the accuracy or completeness of this information and we have not independently verified this information. In addition, the market and industry data and forecasts that may be included or incorporated by reference in this prospectus, any prospectus supplement or any applicable free writing prospectus may involve estimates, assumptions and other risks and uncertainties and are subject to change based on various factors, including those discussed under the heading “Risk Factors” contained in this prospectus, the applicable prospectus supplement and any applicable free writing prospectus, and under similar headings in other documents that are incorporated by reference into this prospectus. Accordingly, investors should not place undue reliance on this information.

When we refer to “Galera,” “we,” “our,” “us” and the “Company” in this prospectus, we mean Galera Therapeutics, Inc. and its consolidated subsidiaries, unless otherwise specified. When we refer to “you,” we mean the potential holders of the applicable series of securities.

TRADEMARKS

This prospectus includes our trademarks and trade names, including, without limitation, GALERA, GALERA THERAPEUTICS and our logo, which are our property and are protected under applicable intellectual property laws. This prospectus also contains trademarks, trade names and service marks of other companies, which are the property of their respective owners. Solely for convenience, trademarks, trade names and service marks referred to in this prospectus may appear without the ^®, ^™ or ^SM symbols, but such references are not intended to indicate, in any way, that we or the applicable owner will not assert, to the fullest extent permitted under applicable law, our or its rights or the right of any applicable licensor to these trademarks, trade names and service marks. We do not intend our use or display of other parties’ trademarks, trade names or service marks to imply, and such use or display should not be construed to imply, a relationship with, or endorsement or sponsorship of us by, these other parties.

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WHERE YOU CAN FIND MORE INFORMATION; INCORPORATION BY REFERENCE

Available Information

We file reports, proxy statements and other information with the SEC. The SEC maintains a web site that contains reports, proxy and information statements and other information about issuers, such as us, who file electronically with the SEC. The address of that website is www.sec.gov.

Our web site address is www.galeratx.com. The information on our web site, however, is not, and shall not be deemed to be, a part of this prospectus.

This prospectus and any prospectus supplement are part of a registration statement that we filed with the SEC, and do not contain all of the information in the registration statement. The full registration statement may be obtained from the SEC or us, as provided below. Forms of the indenture and other documents establishing the terms of the offered securities are or may be filed as exhibits to the registration statement or documents incorporated by reference in the registration statement. Statements in this prospectus or any prospectus supplement about these documents are summaries and each such statement is qualified in all respects by reference to the document to which it refers. You should refer to the actual documents for a more complete description of the relevant matters. You may inspect a copy of the registration statement through the SEC’s website, as provided above.

Incorporation by Reference

The SEC’s rules allow us to “incorporate by reference” information into this prospectus, which means that we can disclose important information to you by referring you to another document filed separately with the SEC. The information incorporated by reference is deemed to be part of this prospectus, and subsequent information that we file with the SEC will automatically update and supersede that information. Any statement contained in this prospectus or a previously filed document incorporated by reference will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in this prospectus or a subsequently filed document incorporated by reference modifies or replaces that statement.

This prospectus and any accompanying prospectus supplement incorporate by reference the documents set forth below that have previously been filed with the SEC (other than those documents or the portions of those documents not deemed to be filed):

All reports and other documents we subsequently file pursuant to Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended, which we refer to as the “Exchange Act” in this prospectus, prior to the termination of this offering, including all such documents we may file with the SEC after the date of the

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initial registration statement and prior to the effectiveness of the registration statement, but excluding any information furnished to, rather than filed with, the SEC, will also be incorporated by reference into this prospectus and deemed to be part of this prospectus from the date of the filing of such reports and documents.

You may request a free copy of any of the documents incorporated by reference in this prospectus by writing or telephoning us at the following address:

GALERA THERAPEUTICS, INC.

2 W. LIBERTY BLVD #100

MALVERN, PENNSYLVANIA 19355

(610) 725-1500

Exhibits to the filings will not be sent, however, unless those exhibits have specifically been incorporated by reference in this prospectus or any accompanying prospectus supplement.

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THE COMPANY

We are a clinical stage biopharmaceutical company focused on developing and commercializing a pipeline of novel, proprietary therapeutics that have the potential to transform radiotherapy in cancer. We leverage our expertise in superoxide dismutase mimetics to design drugs to reduce normal tissue toxicity from radiotherapy and to increase the anti-cancer efficacy of radiotherapy. Our lead product candidate, avasopasem manganese (GC4419 or avasopasem), is a potent and highly selective small molecule dismutase mimetic we are initially developing for the reduction of severe oral mucositis (SOM). SOM is a common, debilitating complication of radiotherapy in patients with head and neck cancer (HNC). The U.S. Food and Drug Administration has granted Fast Track and Breakthrough Therapy designations to avasopasem for the reduction of SOM induced by radiotherapy. Avasopasem is currently being evaluated in a Phase 3 registrational trial to assess its ability to reduce the incidence and severity of SOM induced by radiotherapy in patients with locally advanced HNC. We believe avasopasem, which to date is not approved for any indication, has the potential to be the first FDA-approved drug and the standard of care for the reduction in the incidence of SOM in patients with HNC receiving radiotherapy, and we plan to further evaluate its use in other radiotherapy-induced toxicities, including esophagitis. We are currently evaluating the efficacy of avasopasem in reducing the incidence of radiotherapy-induced esophagitis in patients with lung cancer in a Phase 2a trial.

In addition to developing avasopasem for the reduction of normal tissue toxicity from radiotherapy, we are also developing our dismutase mimetics to increase the anti-cancer efficacy of higher daily doses of radiotherapy, including stereotactic body radiation therapy (SBRT). Our second dismutase mimetic product candidate, GC4711, is being developed specifically to augment the anti-cancer efficacy of SBRT, and is currently being studied in a Phase 1/2 trial in combination with SBRT in patients with non-small cell lung cancer.

We were incorporated in Delaware in November 2012. Our offices are located at 2 W. Liberty Blvd, #100, Malvern, Pennsylvania 19355. Our common stock is listed on the Nasdaq Global Market under the symbol “GRTX.”

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RISK FACTORS

Investment in any securities offered pursuant to this prospectus and the applicable prospectus supplement involves risks. You should carefully consider the risk factors incorporated by reference to our most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q or Current Reports on Form 8-K we file after the date of this prospectus, and all other information contained or incorporated by reference into this prospectus, as updated by our subsequent filings under the Exchange Act, and the risk factors and other information contained in the applicable prospectus supplement and any applicable free writing prospectus before acquiring any of such securities. The occurrence of any of these risks might cause you to lose all or part of your investment in the offered securities.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and any accompanying prospectus supplement and the documents incorporated by reference herein and therein and any free writing prospectus that we have authorized for use in connection with this offering may contain forward-looking statements. In some cases, you can identify forward-looking statements by terms such as “may,” “will,” “should,” “expect,” “plan,” “anticipate,” “could,” “intend,” “target,” “project,” “contemplate,” “believe,” “estimate,” “predict,” “potential” or “continue” or the negative of these terms or other similar expressions, although not all forward-looking statements contain these words. All statements other than statements of historical facts contained in this prospectus and any accompanying prospectus supplement and the documents incorporated by reference herein and therein and any free writing prospectus, including without limitation statements regarding our plans to develop and commercialize our product candidates, the timing of our ongoing or planned clinical trials, the timing of and our ability to obtain and maintain regulatory approvals, the anticipated direct and indirect impact of the COVID-19 pandemic on our business and operations, including manufacturing, research and development costs, clinical trials and employees, the clinical utility of our product candidates, our commercialization, marketing and manufacturing capabilities and strategy, our expectations about the willingness of healthcare professionals to use our product candidates, the sufficiency of our cash, cash equivalents and short-term investments, and the plans and objectives of management for future operations and capital expenditures are forward-looking statements. This prospectus and any accompanying prospectus supplement and the documents incorporated by reference herein and therein and any free writing prospectus may also contain estimates and other statistical data made by independent parties and by us relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates. In addition, projections, assumptions and estimates of our future performance and the future performance of the markets in which we operate are necessarily subject to a high degree of uncertainty and risk.

These forward-looking statements are only predictions and are based largely on our current expectations and projections about future events and financial trends that we believe may affect our business, financial condition and results of operations. These forward-looking statements speak only as of the respective dates of this prospectus and the documents incorporated by reference herein and therein and any free writing prospectus, as applicable, and are subject to a number of risks, uncertainties and assumptions, including, but not limited to, the following: our limited operating history; anticipating continued losses for the foreseeable future; needing substantial funding and the ability to raise capital; our dependence on avasopasem; uncertainties inherent in the conduct of clinical trials; difficulties or delays enrolling patients in clinical trials; the FDA’s acceptance of data from clinical trials outside the United States; undesirable side effects from our product candidates; risks relating to the regulatory approval process; failure to capitalize on more profitable product candidates or indications; ability to receive Breakthrough Therapy Designation or Fast Track Designation for product candidates; failure to obtain regulatory approval of product candidates in the United States or other jurisdictions; ongoing regulatory obligations and continued regulatory review; risks related to commercialization; risks related to competition; ability to retain key employees and manage growth; risks related to intellectual property; inability to maintain collaborations or the failure of these collaborations; our reliance on third parties; the possibility of system

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failures or security breaches; liability related to the privacy of health information obtained from clinical trials and product liability lawsuits; unfavorable pricing regulations, third-party reimbursement practices or healthcare reform initiatives; environmental, health and safety laws and regulations; the impact of the COVID-19 pandemic on our business and operations, including preclinical studies and clinical trials, and general economic conditions; risks related to ownership of our common stock; significant costs as a result of operating as a public company; and those described under “Risk Factors” and elsewhere in this prospectus.

Because forward-looking statements are inherently subject to risks and uncertainties, some of which cannot be predicted or quantified and some of which are beyond our control, you should not rely on these forward-looking statements as predictions of future events. Moreover, we operate in an evolving environment. New risk factors and uncertainties may emerge from time to time, and it is not possible for management to predict all risk factors and uncertainties. Except as required by applicable law, we do not plan to publicly update or revise any forward-looking statements contained in this prospectus and any accompanying prospectus supplement and the documents incorporated by reference herein and therein and any free writing prospectus, whether as a result of any new information, future events, changed circumstances or otherwise.

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USE OF PROCEEDS

We intend to use the net proceeds from the sale of the securities as set forth in the applicable prospectus supplement.

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DESCRIPTION OF CAPITAL STOCK

The following description of our capital stock is not complete and may not contain all the information you should consider before investing in our capital stock. This description is summarized from, and qualified in its entirety by reference to, our certificate of incorporation, which has been publicly filed with the SEC. See “Where You Can Find More Information; Incorporation by Reference.”

Our authorized capital stock consists of 210,000,000 shares, all with a par value of $0.001 per share, of which:

Common Stock

Holders of our common stock are entitled to one vote for each share held on all matters submitted to a vote of stockholders and do not have cumulative voting rights. An election of directors by our stockholders shall be determined by a plurality of the votes cast by the stockholders entitled to vote on the election. Holders of common stock are entitled to receive proportionately any dividends as may be declared by our board of directors, subject to any preferential dividend rights of any series of preferred stock that we may designate and issue in the future.

In the event of our liquidation or dissolution, the holders of common stock are entitled to receive proportionately our net assets available for distribution to stockholders after the payment of all debts and other liabilities and subject to the prior rights of any outstanding preferred stock. Holders of common stock have no preemptive, subscription, redemption or conversion rights. Our outstanding shares of common stock are validly issued, fully paid and nonassessable. The rights, preferences and privileges of holders of common stock are subject to and may be adversely affected by the rights of the holders of shares of any series of preferred stock that we may designate and issue in the future.

Preferred Stock

Under the terms of our restated certificate of incorporation, our board of directors is authorized to direct us to issue shares of preferred stock in one or more series without stockholder approval. Our board of directors has the discretion to determine the rights, preferences, privileges and restrictions, including voting rights, dividend rights, conversion rights, redemption privileges and liquidation preferences, of each series of preferred stock.

The purpose of authorizing our board of directors to issue preferred stock and determine its rights and preferences is to eliminate delays associated with a stockholder vote on specific issuances. The issuance of preferred stock, while providing flexibility in connection with possible acquisitions, future financings and other corporate purposes, could have the effect of making it more difficult for a third-party to acquire, or could discourage a third-party from seeking to acquire, a majority of our outstanding voting stock.

Registration Rights

The second amended and restated investors’ rights agreement by and among us and certain of our stockholders (the “Investors’ Rights Agreement”) grants the parties thereto certain registration rights in respect of the “Registrable Securities” held by them, which securities include (1) the shares of our common stock issuable or issued upon the conversion of shares of our redeemable convertible preferred stock, (2) any shares of our common stock, or any common stock issued or issuable upon conversion and/or exercise of any of our securities acquired by the parties prior to our initial public offering, and (3) any shares of our common stock issued as a dividend or other distribution with respect to the shares described in the foregoing clauses (1) and (2). The registration of shares of our common stock pursuant to the exercise of these registration rights would enable the

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holders thereof to sell such shares without restriction under the Securities Act of 1933, as amended (the “Securities Act”), when the applicable registration statement is declared effective. Under the Investors’ Rights Agreement, we will pay all expenses relating to such registrations, including the reasonable fees of one special counsel for the participating holders, and the holders will pay all underwriting discounts and commissions relating to the sale of their shares. The Investors’ Rights Agreement also includes customary indemnification and procedural terms.

These registration rights will expire on the earlier of (1) November 12, 2024, (2) with respect to each stockholder, at such time as such stockholder can sell all of its shares pursuant to Rule 144 of the Securities Act or another similar exemption under the Securities Act during any three month period without registration, and (3) the closing of a deemed liquidation event, as defined in the Investors’ Rights Agreement.

Demand Registration Rights

At any time after May 4, 2020, the holders of not less than 30% of the Registrable Securities then outstanding may, on not more than two occasions, request that we prepare, file and maintain a registration statement on Form S-1 to register the Registrable Securities of such holders if the anticipated aggregate offering price, net of underwriting discounts and commissions, would be at least $10.0 million. Once we are eligible to use a registration statement on Form S-3, the stockholders party to the Investors’ Rights Agreement may, on not more than two occasions in any 12-month period, request that we prepare, file and maintain a registration statement on Form S-3 covering the sale of their Registrable Securities, but only if the anticipated aggregate offering price, net of underwriting discounts and commissions, would exceed $1.0 million.

Piggyback Registration Rights

In the event that we propose to register any of our securities under the Securities Act, either for our own account or for the account of other security holders, the stockholders party to the Investors’ Rights Agreement will be entitled to certain “piggyback” registration rights allowing them to include their Registrable Securities in such registration, subject to certain marketing and other limitations. As a result, whenever we propose to file a registration statement under the Securities Act other than with respect to a demand registration or a registration statement on Form S-4 or S-8 or a registration in which the only common stock being registered is common stock issuable upon conversion of debt securities that are also being registered, these holders will be entitled to notice of the registration and will have the right to include their Registrable Securities in the registration subject to certain limitations.

Transfer Agent

The transfer agent and registrar for our common stock is American Stock Transfer & Trust Company, LLC.

Dividend

We have never declared or paid any dividends on our capital stock. We currently intend to retain all available funds and any future earnings, if any, for the operation and expansion of our business and, therefore, we do not anticipate declaring or paying cash dividends in the foreseeable future. The payment of dividends, if any, will be at the discretion of our board of directors and will depend on our results of operations, capital requirements, financial condition, prospects, contractual arrangements, any limitations on payment of dividends present in our future debt agreements, and other factors that our board of directors may deem relevant. Our ability to pay cash dividends on our capital stock in the future may also be limited by the terms of any preferred securities we may issue or agreements governing any additional indebtedness we may incur.

Anti-Takeover Effects of Delaware Law and Our Certificate of Incorporation and Bylaws

Some provisions of Delaware law, our restated certificate of incorporation and our amended and restated bylaws could make the following transactions more difficult: an acquisition of us by means of a tender offer; an

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acquisition of us by means of a proxy contest or otherwise; or the removal of our incumbent officers and directors. It is possible that these provisions could make it more difficult to accomplish or could deter transactions that stockholders may otherwise consider to be in their best interest or in our best interests, including transactions which provide for payment of a premium over the market price for our shares.

These provisions, summarized below, are intended to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to encourage persons seeking to acquire control of us to first negotiate with our board of directors. We believe that the benefits of the increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure us outweigh the disadvantages of discouraging these proposals because negotiation of these proposals could result in an improvement of their terms.

Undesignated Preferred Stock

The ability of our board of directors, without action by the stockholders, to issue up to 10,000,000 shares of undesignated preferred stock with voting or other rights or preferences as designated by our board of directors could impede the success of any attempt to change control of us. These and other provisions may have the effect of deferring hostile takeovers or delaying changes in control or management of our company.

Stockholder Meetings

Our amended and restated bylaws provide that a special meeting of stockholders may be called only by our chairman of the board, chief executive officer or president (in the absence of a chief executive officer), or by a resolution adopted by a majority of our board of directors.

Requirements for Advance Notification of Stockholder Nominations and Proposals

Our amended and restated bylaws establish advance notice procedures with respect to stockholder proposals to be brought before a stockholder meeting and the nomination of candidates for election as directors, other than nominations made by or at the direction of the board of directors or a committee of the board of directors.

Elimination of Stockholder Action by Written Consent

Our restated certificate of incorporation eliminates the right of stockholders to act by written consent without a meeting.

Staggered Board

Our board of directors is divided into three classes. The directors in each class will serve for a three-year term, one class being elected each year by our stockholders. This system of electing and removing directors may tend to discourage a third party from making a tender offer or otherwise attempting to obtain control of us, because it generally makes it more difficult for stockholders to replace a majority of the directors.

Removal of Directors

Our restated certificate of incorporation provides that no member of our board of directors may be removed from office by our stockholders except for cause and, in addition to any other vote required by law, upon the approval of the holders of at least two-thirds in voting power of the outstanding shares of stock entitled to vote in the election of directors.

Stockholders Not Entitled to Cumulative Voting

Our restated certificate of incorporation will not permit stockholders to cumulate their votes in the election of directors. Accordingly, the holders of a majority of the outstanding shares of our common stock entitled to

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vote in any election of directors can elect all of the directors standing for election, if they choose, other than any directors that holders of our preferred stock may be entitled to elect.

Delaware Anti-Takeover Statute

We are subject to Section 203 of the General Corporation Law of the State of Delaware, which prohibits persons deemed to be “interested stockholders” from engaging in a “business combination” with a publicly held Delaware corporation for three years following the date these persons become interested stockholders unless the business combination is, or the transaction in which the person became an interested stockholder was, approved in a prescribed manner or another prescribed exception applies. Generally, an “interested stockholder” is a person who, together with affiliates and associates, owns, or within three years prior to the determination of interested stockholder status did own, 15% or more of a corporation’s voting stock. Generally, a “business combination” includes a merger, asset or stock sale, or other transaction resulting in a financial benefit to the interested stockholder. The existence of this provision may have an anti-takeover effect with respect to transactions not approved in advance by the board of directors.

Choice of Forum

Our restated certificate of incorporation provides that, unless we consent in writing to the selection of an alternative form, the Court of Chancery of the State of Delaware will be the sole and exclusive forum for: (1) any derivative action or proceeding brought on our behalf; (2) any action asserting a claim of breach of a fiduciary duty or other wrongdoing by any of our directors, officers, employees or stockholders to us or our stockholders; (3) any action asserting a claim against us arising pursuant to any provision of the General Corporation Law of the State of Delaware or our certificate of incorporation or bylaws; or (4) any action asserting a claim governed by the internal affairs doctrine. Under our restated certificate of incorporation, this exclusive forum provision will not apply to claims which are vested in the exclusive jurisdiction of a court or forum other than the Court of Chancery of the State of Delaware, or for which the Court of Chancery of the State of Delaware does not have subject matter jurisdiction. For instance, the provision would not apply to actions arising under federal securities laws, including suits brought to enforce any liability or duty created by the Securities Act, Exchange Act, or the rules and regulations thereunder. This provision would not apply to suits brought to enforce a duty or liability created by the Exchange Act. Our restated certificate of incorporation also provides that any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock will be deemed to have notice of and to have consented to this choice of forum provision. It is possible that a court of law could rule that the choice of forum provision contained in our restated certificate of incorporation is inapplicable or unenforceable if it is challenged in a proceeding or otherwise.

Amendment of Charter Provisions

The amendment of any of the above provisions, except for the provision making it possible for our board of directors to issue preferred stock and the provision prohibiting cumulative voting, would require approval by holders of at least two-thirds in voting power of the outstanding shares of stock entitled to vote thereon. The provisions of Delaware law, our restated certificate of incorporation and our amended and restated bylaws could have the effect of discouraging others from attempting hostile takeovers and, as a consequence, they may also inhibit temporary fluctuations in the market price of our common stock that often result from actual or rumored hostile takeover attempts. These provisions may also have the effect of preventing changes in the composition of our board and management. It is possible that these provisions could make it more difficult to accomplish transactions that stockholders may otherwise deem to be in their best interests.

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DESCRIPTION OF DEBT SECURITIES

The following description, together with the additional information we include in any applicable prospectus supplement or free writing prospectus, summarizes certain general terms and provisions of the debt securities that we may offer under this prospectus. When we offer to sell a particular series of debt securities, we will describe the specific terms of the series in a supplement to this prospectus. We will also indicate in the supplement to what extent the general terms and provisions described in this prospectus apply to a particular series of debt securities.

We may issue debt securities either separately, or together with, or upon the conversion or exercise of or in exchange for, other securities described in this prospectus. Debt securities may be our senior, senior subordinated or subordinated obligations and, unless otherwise specified in a supplement to this prospectus, the debt securities will be our direct, unsecured obligations and may be issued in one or more series.

The debt securities will be issued under an indenture between us and a trustee to be named in the applicable indenture. We have summarized select portions of the indenture below. The summary is not complete. The form of the indenture has been filed as an exhibit to the registration statement and you should read the indenture for provisions that may be important to you. In the summary below, we have included references to the section numbers of the indenture so that you can easily locate these provisions. Capitalized terms used in the summary and not defined herein have the meanings specified in the indenture.

As used in this section only, “Galera,” “we,” “our” or “us” refer to Galera Therapeutics, Inc. excluding our subsidiaries, unless expressly stated or the context otherwise requires.

General

The terms of each series of debt securities will be established by or pursuant to a resolution of our board of directors and set forth or determined in the manner provided in a resolution of our board of directors, in an officer’s certificate or by a supplemental indenture. (Section 2.2) The particular terms of each series of debt securities will be described in a prospectus supplement relating to such series (including any pricing supplement or term sheet).

We can issue an unlimited amount of debt securities under the indenture that may be in one or more series with the same or various maturities, at par, at a premium, or at a discount. (Section 2.1) We will set forth in a prospectus supplement (including any pricing supplement or term sheet) relating to any series of debt securities being offered, the aggregate principal amount and the following terms of the debt securities, if applicable:

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We may issue debt securities that provide for an amount less than their stated principal amount to be due and payable upon declaration of acceleration of their maturity pursuant to the terms of the indenture. We will provide you with information on the federal income tax considerations and other special considerations applicable to any of these debt securities in the applicable prospectus supplement.

If we denominate the purchase price of any of the debt securities in a foreign currency or currencies or a foreign currency unit or units, or if the principal of and any premium and interest on any series of debt securities is payable in a foreign currency or currencies or a foreign currency unit or units, we will provide you with information on the restrictions, elections, general tax considerations, specific terms and other information with respect to that issue of debt securities and such foreign currency or currencies or foreign currency unit or units in the applicable prospectus supplement.

Transfer and Exchange

Each debt security will be represented by either one or more global securities registered in the name of The Depository Trust Company, or the Depositary, or a nominee of the Depositary (we will refer to any debt security represented by a global debt security as a “book-entry debt security”), or a certificate issued in definitive registered form (we will refer to any debt security represented by a certificated security as a “certificated debt security”) as set forth in the applicable prospectus supplement. Except as set forth under the heading “Global Debt Securities and Book-Entry System” below, book-entry debt securities will not be issuable in certificated form.

Certificated Debt Securities. You may transfer or exchange certificated debt securities at any office we maintain for this purpose in accordance with the terms of the indenture. (Section 2.4) No service charge will be made for any transfer or exchange of certificated debt securities, but we may require payment of a sum sufficient to cover any tax or other governmental charge payable in connection with a transfer or exchange. (Section 2.7)

You may effect the transfer of certificated debt securities and the right to receive the principal of, premium and interest on certificated debt securities only by surrendering the certificate representing those certificated debt securities and either reissuance by us or the trustee of the certificate to the new holder or the issuance by us or the trustee of a new certificate to the new holder.

Global Debt Securities and Book-Entry System. Each global debt security representing book-entry debt securities will be deposited with, or on behalf of, the Depositary, and registered in the name of the Depositary or a nominee of the Depositary. Please see “Global Securities.”

Covenants

We will set forth in the applicable prospectus supplement any restrictive covenants applicable to any issue of debt securities. (Article IV)

No Protection in the Event of a Change of Control

Unless we state otherwise in the applicable prospectus supplement, the debt securities will not contain any provisions which may afford holders of the debt securities protection in the event we have a change in control or in the event of a highly leveraged transaction (whether or not such transaction results in a change in control) which could adversely affect holders of debt securities.

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Consolidation, Merger and Sale of Assets

We may not consolidate with or merge with or into, or convey, transfer or lease all or substantially all of our properties and assets to any person (a “successor person”) unless:

Notwithstanding the above, any of our subsidiaries may consolidate with, merge into or transfer all or part of its properties to us. (Section 5.1)

Events of Default

“Event of Default” means with respect to any series of debt securities, any of the following:

No Event of Default with respect to a particular series of debt securities (except as to certain events of bankruptcy, insolvency or reorganization) necessarily constitutes an Event of Default with respect to any other series of debt securities. (Section 6.1) The occurrence of certain Events of Default or an acceleration under the indenture may constitute an event of default under certain indebtedness of ours or our subsidiaries outstanding from time to time.

We will provide the trustee written notice of any Default or Event of Default within 30 days of becoming aware of the occurrence of such Default or Event of Default, which notice will describe in reasonable detail the status of such Default or Event of Default and what action we are taking or propose to take in respect thereof. (Section 6.1)

If an Event of Default with respect to debt securities of any series at the time outstanding occurs and is continuing, then the trustee or the holders of not less than 25% in principal amount of the outstanding debt securities of that series may, by a notice in writing to us (and to the trustee if given by the holders), declare to be due and payable immediately the principal of (or, if the debt securities of that series are discount securities, that portion of the principal amount as may be specified in the terms of that series) and accrued and unpaid interest, if any, on all debt securities of that series. In the case of an Event of Default resulting from certain events of bankruptcy, insolvency or reorganization, the principal (or such specified amount) of and accrued and unpaid

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interest, if any, on all outstanding debt securities will become and be immediately due and payable without any declaration or other act on the part of the trustee or any holder of outstanding debt securities. At any time after a declaration of acceleration with respect to debt securities of any series has been made, but before a judgment or decree for payment of the money due has been obtained by the trustee, the holders of a majority in principal amount of the outstanding debt securities of that series may rescind and annul the acceleration if all Events of Default, other than the non-payment of accelerated principal and interest, if any, with respect to debt securities of that series, have been cured or waived as provided in the indenture. (Section 6.2) We refer you to the prospectus supplement relating to any series of debt securities that are discount securities for the particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of an Event of Default.

The indenture provides that the trustee may refuse to perform any duty or exercise any of its rights or powers under the indenture unless the trustee receives indemnity satisfactory to it against any cost, liability or expense which might be incurred by it in performing such duty or exercising such right or power. (Section 7.1(e)) Subject to certain rights of the trustee, the holders of a majority in principal amount of the outstanding debt securities of any series will have the right to direct the time, method and place of conducting any proceeding for any remedy available to the trustee or exercising any trust or power conferred on the trustee with respect to the debt securities of that series. (Section 6.12)

No holder of any debt security of any series will have any right to institute any proceeding, judicial or otherwise, with respect to the indenture or for the appointment of a receiver or trustee, or for any remedy under the indenture, unless:

Notwithstanding any other provision in the indenture, the holder of any debt security will have an absolute and unconditional right to receive payment of the principal of, premium and any interest on that debt security on or after the due dates expressed in that debt security and to institute suit for the enforcement of payment. (Section 6.8)

The indenture requires us, within 120 days after the end of our fiscal year, to furnish to the trustee a statement as to compliance with the indenture. (Section 4.3) If a Default or Event of Default occurs and is continuing with respect to the securities of any series and if it is known to a responsible officer of the trustee, the trustee shall mail to each Securityholder of the securities of that series notice of a Default or Event of Default within 90 days after it occurs or, if later, after a responsible officer of the trustee has knowledge of such Default or Event of Default. The indenture provides that the trustee may withhold notice to the holders of debt securities of any series of any Default or Event of Default (except in payment on any debt securities of that series) with respect to debt securities of that series if the trustee determines in good faith that withholding notice is in the interest of the holders of those debt securities. (Section 7.5)

Modification and Waiver

We and the trustee may modify, amend or supplement the indenture or the debt securities of any series without the consent of any holder of any debt security:

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We may also modify and amend the indenture with the consent of the holders of at least a majority in principal amount of the outstanding debt securities of each series affected by the modifications or amendments. We may not make any modification or amendment without the consent of the holders of each affected debt security then outstanding if that amendment will:

Except for certain specified provisions, the holders of at least a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all debt securities of that series waive our compliance with provisions of the indenture. (Section 9.2) The holders of a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all the debt securities of such series waive any past default under the indenture with respect to that series and its consequences, except a default in the payment of the principal of, premium or any interest on any debt security of that series; provided, however, that

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the holders of a majority in principal amount of the outstanding debt securities of any series may rescind an acceleration and its consequences, including any related payment default that resulted from the acceleration. (Section 6.13)

Defeasance of Debt Securities and Certain Covenants in Certain Circumstances

Legal Defeasance. The indenture provides that, unless otherwise provided by the terms of the applicable series of debt securities, we may be discharged from any and all obligations in respect of the debt securities of any series (subject to certain exceptions). We will be so discharged upon the irrevocable deposit with the trustee, in trust, of money and/or U.S. government obligations or, in the case of debt securities denominated in a single currency other than U.S. Dollars, government obligations of the government that issued or caused to be issued such currency, that, through the payment of interest and principal in accordance with their terms, will provide money or U.S. government obligations in an amount sufficient in the opinion of a nationally recognized firm of independent public accountants or investment bank to pay and discharge each installment of principal, premium and interest on and any mandatory sinking fund payments in respect of the debt securities of that series on the stated maturity of those payments in accordance with the terms of the indenture and those debt securities.

This discharge may occur only if, among other things, we have delivered to the trustee an opinion of counsel stating that we have received from, or there has been published by, the United States Internal Revenue Service a ruling or, since the date of execution of the indenture, there has been a change in the applicable United States federal income tax law, in either case to the effect that, and based thereon such opinion shall confirm that, the holders of the debt securities of that series will not recognize income, gain or loss for United States federal income tax purposes as a result of the deposit, defeasance and discharge and will be subject to United States federal income tax on the same amounts and in the same manner and at the same times as would have been the case if the deposit, defeasance and discharge had not occurred. (Section 8.3)

Defeasance of Certain Covenants. The indenture provides that, unless otherwise provided by the terms of the applicable series of debt securities, upon compliance with certain conditions:

The conditions include:

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No Personal Liability of Directors, Officers, Employees or Securityholders

None of our past, present or future directors, officers, employees or securityholders, as such, will have any liability for any of our obligations under the debt securities or the indenture or for any claim based on, or in respect or by reason of, such obligations or their creation. By accepting a debt security, each holder waives and releases all such liability. This waiver and release is part of the consideration for the issue of the debt securities. However, this waiver and release may not be effective to waive liabilities under U.S. federal securities laws, and it is the view of the SEC that such a waiver is against public policy.

Governing Law

The indenture and the debt securities, including any claim or controversy arising out of or relating to the indenture or the securities, will be governed by the laws of the State of New York.

The indenture will provide that we, the trustee and the holders of the debt securities (by their acceptance of the debt securities) irrevocably waive, to the fullest extent permitted by applicable law, any and all right to trial by jury in any legal proceeding arising out of or relating to the indenture, the debt securities or the transactions contemplated thereby.

The indenture will provide that any legal suit, action or proceeding arising out of or based upon the indenture or the transactions contemplated thereby may be instituted in the federal courts of the United States of America located in the City of New York or the courts of the State of New York in each case located in the City of New York, and we, the trustee and the holder of the debt securities (by their acceptance of the debt securities) irrevocably submit to the non-exclusive jurisdiction of such courts in any such suit, action or proceeding. The indenture will further provide that service of any process, summons, notice or document by mail (to the extent allowed under any applicable statute or rule of court) to such party’s address set forth in the indenture will be effective service of process for any suit, action or other proceeding brought in any such court. The indenture will further provide that we, the trustee and the holders of the debt securities (by their acceptance of the debt securities) irrevocably and unconditionally waive any objection to the laying of venue of any suit, action or other proceeding in the courts specified above and irrevocably and unconditionally waive and agree not to plead or claim any such suit, action or other proceeding has been brought in an inconvenient forum. (Section 10.10)

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DESCRIPTION OF WARRANTS

We may issue warrants for the purchase of shares of our common stock or preferred stock or of debt securities. We may issue warrants independently or together with other securities, and the warrants may be attached to or separate from any offered securities. Each series of warrants will be issued under a separate warrant agreement to be entered into between us and the investors or a warrant agent. The following summary of material provisions of the warrants and warrant agreements are subject to, and qualified in their entirety by reference to, all the provisions of the warrant agreement and warrant certificate applicable to a particular series of warrants. The terms of any warrants offered under a prospectus supplement may differ from the terms described below. We urge you to read the applicable prospectus supplement and any related free writing prospectus, as well as the complete warrant agreements and warrant certificates that contain the terms of the warrants.

The particular terms of any issue of warrants will be described in the prospectus supplement relating to the issue. Those terms may include:

Holders of equity warrants will not be entitled:

Each warrant will entitle its holder to purchase the principal amount of debt securities or the number of shares of preferred stock or common stock at the exercise price set forth in, or calculable as set forth in, the applicable prospectus supplement. Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants at any time up to the specified time on the expiration date that we set forth in the applicable prospectus supplement. After the close of business on the expiration date, unexercised warrants will become void.

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A holder of warrant certificates may exchange them for new warrant certificates of different denominations, present them for registration of transfer and exercise them at the corporate trust office of the warrant agent or any other office indicated in the applicable prospectus supplement. Until any warrants to purchase debt securities are exercised, the holder of the warrants will not have any rights of holders of the debt securities that can be purchased upon exercise, including any rights to receive payments of principal, premium or interest on the underlying debt securities or to enforce covenants in the applicable indenture. Until any warrants to purchase common stock or preferred stock are exercised, the holders of the warrants will not have any rights of holders of the underlying common stock or preferred stock, including any rights to receive dividends or payments upon any liquidation, dissolution or winding up on the common stock or preferred stock, if any.

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DESCRIPTION OF UNITS

We may issue units consisting of any combination of the other types of securities offered under this prospectus in one or more series. We may evidence each series of units by unit certificates that we will issue under a separate agreement. We may enter into unit agreements with a unit agent. Each unit agent will be a bank or trust company that we select. We will indicate the name and address of the unit agent in the applicable prospectus supplement relating to a particular series of units.

The following description, together with the additional information included in any applicable prospectus supplement, summarizes the general features of the units that we may offer under this prospectus. You should read any prospectus supplement and any free writing prospectus that we may authorize to be provided to you related to the series of units being offered, as well as the complete unit agreements that contain the terms of the units. Specific unit agreements will contain additional important terms and provisions and we will file as an exhibit to the registration statement of which this prospectus is a part, or will incorporate by reference from another report that we file with the SEC, the form of each unit agreement relating to units offered under this prospectus.

If we offer any units, certain terms of that series of units will be described in the applicable prospectus supplement, including, without limitation, the following, as applicable:

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GLOBAL SECURITIES

Book-Entry, Delivery and Form

Unless we indicate differently in any applicable prospectus supplement or free writing prospectus, the securities initially will be issued in book-entry form and represented by one or more global notes or global securities, or, collectively, global securities. The global securities will be deposited with, or on behalf of, The Depository Trust Company, New York, New York, as depositary, or DTC, and registered in the name of Cede & Co., the nominee of DTC. Unless and until it is exchanged for individual certificates evidencing securities under the limited circumstances described below, a global security may not be transferred except as a whole by the depositary to its nominee or by the nominee to the depositary, or by the depositary or its nominee to a successor depositary or to a nominee of the successor depositary.

DTC has advised us that it is:

DTC holds securities that its participants deposit with DTC. DTC also facilitates the settlement among its participants of securities transactions, such as transfers and pledges, in deposited securities through electronic computerized book-entry changes in participants’ accounts, thereby eliminating the need for physical movement of securities certificates. “Direct participants” in DTC include securities brokers and dealers, including underwriters, banks, trust companies, clearing corporations and other organizations. DTC is a wholly-owned subsidiary of The Depository Trust & Clearing Corporation, or DTCC. DTCC is the holding company for DTC, National Securities Clearing Corporation and Fixed Income Clearing Corporation, all of which are registered clearing agencies. DTCC is owned by the users of its regulated subsidiaries. Access to the DTC system is also available to others, which we sometimes refer to as indirect participants, that clear through or maintain a custodial relationship with a direct participant, either directly or indirectly. The rules applicable to DTC and its participants are on file with the SEC.

Purchases of securities under the DTC system must be made by or through direct participants, which will receive a credit for the securities on DTC’s records. The ownership interest of the actual purchaser of a security, which we sometimes refer to as a beneficial owner, is in turn recorded on the direct and indirect participants’ records. Beneficial owners of securities will not receive written confirmation from DTC of their purchases. However, beneficial owners are expected to receive written confirmations providing details of their transactions, as well as periodic statements of their holdings, from the direct or indirect participants through which they purchased securities. Transfers of ownership interests in global securities are to be accomplished by entries made on the books of participants acting on behalf of beneficial owners. Beneficial owners will not receive certificates representing their ownership interests in the global securities, except under the limited circumstances described below.

To facilitate subsequent transfers, all global securities deposited by direct participants with DTC will be registered in the name of DTC’s partnership nominee, Cede & Co., or such other name as may be requested by an authorized representative of DTC. The deposit of securities with DTC and their registration in the name of Cede & Co. or such other nominee will not change the beneficial ownership of the securities. DTC has no knowledge of the actual beneficial owners of the securities. DTC’s records reflect only the identity of the direct participants to whose accounts the securities are credited, which may or may not be the beneficial owners. The participants are responsible for keeping account of their holdings on behalf of their customers.

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So long as the securities are in book-entry form, you will receive payments and may transfer securities only through the facilities of the depositary and its direct and indirect participants. We will maintain an office or agency in the location specified in the prospectus supplement for the applicable securities, where notices and demands in respect of the securities and the indenture may be delivered to us and where certificated securities may be surrendered for payment, registration of transfer or exchange.

Conveyance of notices and other communications by DTC to direct participants, by direct participants to indirect participants and by direct participants and indirect participants to beneficial owners will be governed by arrangements among them, subject to any legal requirements in effect from time to time.

Redemption notices will be sent to DTC. If less than all of the securities of a particular series are being redeemed, DTC’s practice is to determine by lot the amount of the interest of each direct participant in the securities of such series to be redeemed.

Neither DTC nor Cede & Co. (or such other DTC nominee) will consent or vote with respect to the securities. Under its usual procedures, DTC will mail an omnibus proxy to us as soon as possible after the record date. The omnibus proxy assigns the consenting or voting rights of Cede & Co. to those direct participants to whose accounts the securities of such series are credited on the record date, identified in a listing attached to the omnibus proxy.

So long as securities are in book-entry form, we will make payments on those securities to the depositary or its nominee, as the registered owner of such securities, by wire transfer of immediately available funds. If securities are issued in definitive certificated form under the limited circumstances described below and unless if otherwise provided in the description of the applicable securities herein or in the applicable prospectus supplement, we will have the option of making payments by check mailed to the addresses of the persons entitled to payment or by wire transfer to bank accounts in the United States designated in writing to the applicable trustee or other designated party at least 15 days before the applicable payment date by the persons entitled to payment, unless a shorter period is satisfactory to the applicable trustee or other designated party.

Redemption proceeds, distributions and dividend payments on the securities will be made to Cede & Co., or such other nominee as may be requested by an authorized representative of DTC. DTC’s practice is to credit direct participants’ accounts upon DTC’s receipt of funds and corresponding detail information from us on the payment date in accordance with their respective holdings shown on DTC records. Payments by participants to beneficial owners will be governed by standing instructions and customary practices, as is the case with securities held for the account of customers in bearer form or registered in “street name.” Those payments will be the responsibility of participants and not of DTC or us, subject to any statutory or regulatory requirements in effect from time to time. Payment of redemption proceeds, distributions and dividend payments to Cede & Co., or such other nominee as may be requested by an authorized representative of DTC, is our responsibility, disbursement of payments to direct participants is the responsibility of DTC, and disbursement of payments to the beneficial owners is the responsibility of direct and indirect participants.

Except under the limited circumstances described below, purchasers of securities will not be entitled to have securities registered in their names and will not receive physical delivery of securities. Accordingly, each beneficial owner must rely on the procedures of DTC and its participants to exercise any rights under the securities and the indenture.

The laws of some jurisdictions may require that some purchasers of securities take physical delivery of securities in definitive form. Those laws may impair the ability to transfer or pledge beneficial interests in securities.

DTC may discontinue providing its services as securities depositary with respect to the securities at any time by giving reasonable notice to us. Under such circumstances, in the event that a successor depositary is not obtained, securities certificates are required to be printed and delivered.

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As noted above, beneficial owners of a particular series of securities generally will not receive certificates representing their ownership interests in those securities. However, if:

we will prepare and deliver certificates for such securities in exchange for beneficial interests in the global securities. Any beneficial interest in a global security that is exchangeable under the circumstances described in the preceding sentence will be exchangeable for securities in definitive certificated form registered in the names that the depositary directs. It is expected that these directions will be based upon directions received by the depositary from its participants with respect to ownership of beneficial interests in the global securities.

Euroclear and Clearstream

If so provided in the applicable prospectus supplement, you may hold interests in a global security through Clearstream Banking S.A., which we refer to as “Clearstream,” or Euroclear Bank S.A./N.V., as operator of the Euroclear System, which we refer to as “Euroclear,” either directly if you are a participant in Clearstream or Euroclear or indirectly through organizations which are participants in Clearstream or Euroclear. Clearstream and Euroclear will hold interests on behalf of their respective participants through customers’ securities accounts in the names of Clearstream and Euroclear, respectively, on the books of their respective U.S. depositaries, which in turn will hold such interests in customers’ securities accounts in such depositaries’ names on DTC’s books.

Clearstream and Euroclear are securities clearance systems in Europe. Clearstream and Euroclear hold securities for their respective participating organizations and facilitate the clearance and settlement of securities transactions between those participants through electronic book-entry changes in their accounts, thereby eliminating the need for physical movement of certificates.

Payments, deliveries, transfers, exchanges, notices and other matters relating to beneficial interests in global securities owned through Euroclear or Clearstream must comply with the rules and procedures of those systems. Transactions between participants in Euroclear or Clearstream, on one hand, and other participants in DTC, on the other hand, are also subject to DTC’s rules and procedures.

Investors will be able to make and receive through Euroclear and Clearstream payments, deliveries, transfers and other transactions involving any beneficial interests in global securities held through those systems only on days when those systems are open for business. Those systems may not be open for business on days when banks, brokers and other institutions are open for business in the United States.

Cross-market transfers between participants in DTC, on the one hand, and participants in Euroclear or Clearstream, on the other hand, will be effected through DTC in accordance with the DTC’s rules on behalf of Euroclear or Clearstream, as the case may be, by their respective U.S. depositaries; however, such cross-market transactions will require delivery of instructions to Euroclear or Clearstream, as the case may be, by the counterparty in such system in accordance with the rules and procedures and within the established deadlines (European time) of such system. Euroclear or Clearstream, as the case may be, will, if the transaction meets its settlement requirements, deliver instructions to its U.S. depositary to take action to effect final settlement on its behalf by delivering or receiving interests in the global securities through DTC, and making or receiving payment in accordance with normal procedures for same-day fund settlement. Participants in Euroclear or Clearstream may not deliver instructions directly to their respective U.S. depositaries.

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Due to time zone differences, the securities accounts of a participant in Euroclear or Clearstream purchasing an interest in a global security from a direct participant in DTC will be credited, and any such crediting will be reported to the relevant participant in Euroclear or Clearstream, during the securities settlement processing day (which must be a business day for Euroclear or Clearstream) immediately following the settlement date of DTC. Cash received in Euroclear or Clearstream as a result of sales of interests in a global security by or through a participant in Euroclear or Clearstream to a direct participant in DTC will be received with value on the settlement date of DTC but will be available in the relevant Euroclear or Clearstream cash account only as of the business day for Euroclear or Clearstream following DTC’s settlement date.

Other

The information in this section of this prospectus concerning DTC, Clearstream, Euroclear and their respective book-entry systems has been obtained from sources that we believe to be reliable, but we do not take responsibility for this information. This information has been provided solely as a matter of convenience. The rules and procedures of DTC, Clearstream and Euroclear are solely within the control of those organizations and could change at any time. Neither we nor the trustee nor any agent of ours or of the trustee has any control over those entities and none of us takes any responsibility for their activities. You are urged to contact DTC, Clearstream and Euroclear or their respective participants directly to discuss those matters. In addition, although we expect that DTC, Clearstream and Euroclear will perform the foregoing procedures, none of them is under any obligation to perform or continue to perform such procedures and such procedures may be discontinued at any time. Neither we nor any agent of ours will have any responsibility for the performance or nonperformance by DTC, Clearstream and Euroclear or their respective participants of these or any other rules or procedures governing their respective operations.

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PLAN OF DISTRIBUTION

We may sell the securities from time to time pursuant to underwritten public offerings, negotiated transactions, block trades or a combination of these methods or through underwriters or dealers, through agents and/or directly to one or more purchasers. The securities may be distributed from time to time in one or more transactions:

Each time that we sell securities covered by this prospectus, we will provide a prospectus supplement or supplements that will describe the method of distribution and set forth the terms and conditions of the offering of such securities, including the offering price of the securities and the proceeds to us, if applicable.

Offers to purchase the securities being offered by this prospectus may be solicited directly. Agents may also be designated to solicit offers to purchase the securities from time to time. Any agent involved in the offer or sale of our securities will be identified in a prospectus supplement.

If a dealer is utilized in the sale of the securities being offered by this prospectus, the securities will be sold to the dealer, as principal. The dealer may then resell the securities to the public at varying prices to be determined by the dealer at the time of resale.

If an underwriter is utilized in the sale of the securities being offered by this prospectus, an underwriting agreement will be executed with the underwriter at the time of sale and the name of any underwriter will be provided in the prospectus supplement that the underwriter will use to make resales of the securities to the public. In connection with the sale of the securities, we, or the purchasers of securities for whom the underwriter may act as agent, may compensate the underwriter in the form of underwriting discounts or commissions. The underwriter may sell the securities to or through dealers, and those dealers may receive compensation in the form of discounts, concessions or commissions from the underwriters and/or commissions from the purchasers for which they may act as agent. Unless otherwise indicated in a prospectus supplement, an agent will be acting on a best efforts basis and a dealer will purchase securities as a principal, and may then resell the securities at varying prices to be determined by the dealer.

Any compensation paid to underwriters, dealers or agents in connection with the offering of the securities, and any discounts, concessions or commissions allowed by underwriters to participating dealers will be provided in the applicable prospectus supplement. Underwriters, dealers and agents participating in the distribution of the securities may be deemed to be underwriters within the meaning of the Securities Act of 1933, as amended, and any discounts and commissions received by them and any profit realized by them on resale of the securities may be deemed to be underwriting discounts and commissions. We may enter into agreements to indemnify underwriters, dealers and agents against civil liabilities, including liabilities under the Securities Act, or to contribute to payments they may be required to make in respect thereof and to reimburse those persons for certain expenses.

Any common stock will be listed on the Nasdaq Global Market, but any other securities may or may not be listed on a national securities exchange. To facilitate the offering of securities, certain persons participating in the offering may engage in transactions that stabilize, maintain or otherwise affect the price of the securities. This may include over-allotments or short sales of the securities, which involve the sale by persons participating in the offering of more securities than were sold to them. In these circumstances, these persons would cover such over-allotments or short positions by making purchases in the open market or by exercising their over-allotment

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option, if any. In addition, these persons may stabilize or maintain the price of the securities by bidding for or purchasing securities in the open market or by imposing penalty bids, whereby selling concessions allowed to dealers participating in the offering may be reclaimed if securities sold by them are repurchased in connection with stabilization transactions. The effect of these transactions may be to stabilize or maintain the market price of the securities at a level above that which might otherwise prevail in the open market. These transactions may be discontinued at any time.

We may engage in at the market offerings into an existing trading market in accordance with Rule 415(a)(4) under the Securities Act. In addition, we may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement so indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by us or borrowed from us or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from us in settlement of those derivatives to close out any related open borrowings of stock. The third party in such sale transactions will be an underwriter and, if not identified in this prospectus, will be named in the applicable prospectus supplement (or a post-effective amendment). In addition, we may otherwise loan or pledge securities to a financial institution or other third party that in turn may sell the securities short using this prospectus and an applicable prospectus supplement. Such financial institution or other third party may transfer its economic short position to investors in our securities or in connection with a concurrent offering of other securities.

The specific terms of any lock-up provisions in respect of any given offering will be described in the applicable prospectus supplement.

The underwriters, dealers and agents may engage in transactions with us, or perform services for us, in the ordinary course of business for which they receive compensation.

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LEGAL MATTERS

Latham & Watkins LLP will pass upon certain legal matters relating to the issuance and sale of the securities offered hereby on behalf of Galera Therapeutics, Inc. Additional legal matters may be passed upon for us or any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of Galera Therapeutics, Inc. as of December 31, 2019 and 2018, and for the years then ended, have been incorporated by reference herein and in the registration statement in reliance upon the report of KPMG LLP, independent registered public accounting firm, incorporated by reference herein, and upon the authority of said firm as experts in accounting and auditing.

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14,320,000 shares of Common Stock

Warrants to purchase up to 14,320,000 shares of Common Stock

PROSPECTUS SUPPLEMENT

Sole Placement Agent

Piper Sandler

February 15, 2023