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ABOUT THIS PROSPECTUS

This prospectus is a part of a registration statement on Form S-3 that we filed with the U.S. Securities and Exchange Commission, (the “SEC”), usingor SEC, utilizing a “shelf” registration process. By using suchUnder this shelf registration statement,process, we may sell any combination of the selling stockholders identified herein may, from time to time, offer and sell (insecurities described in this prospectus in one or more transactions as described under “Plan of Distribution”)offerings up to 22,112,775 sharesa total aggregate offering price of our common stock underlying our Series A Convertible Preferred Stock issued in our private placement offering which closed on August 2, 2017. We will not receive any of$300,000,000, subject to the proceeds from the sales of the common stock by the selling stockholders.

Baby Shelf Limitation. This prospectus provides you with a general description of usthe securities we may offer.

Each time we sell securities under this prospectus, we will provide a prospectus supplement that will contain specific information about the 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 and our securities. Weany related free writing prospectus that we may authorize to be provided to you may also add, update or change in a prospectus supplement any of the information contained in this prospectus or thein any documents incorporated by reference. For further information about our business and our securities, you should refer to the registration statement and the reportsthat we have incorporated by reference ininto this prospectus. You should read this prospectus, any applicable prospectus supplement and any related free writing prospectus, together with the information incorporated herein by reference as described in “Additional Information” andunder the heading “Incorporation of Certain Information by Reference”.Reference,” before investing in any of the securities offered.

You must not rely uponTHIS PROSPECTUS MAY NOT BE USED TO CONSUMMATE A SALE OF SECURITIES UNLESS IT IS ACCOMPANIED BY A PROSPECTUS SUPPLEMENT.

Neither we, nor any agent, underwriter or dealer has authorized any person to give any information or to make any representation notother than those contained or incorporated by reference in this prospectus. You should rely onlyprospectus, any applicable prospectus supplement or any related free writing prospectus prepared by or on the information contained inbehalf of us or to which we have referred you. This prospectus, any applicable supplement to this prospectus andor any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus, any applicable supplement to this prospectus or any related free writing prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any prospectus supplement (includingjurisdiction to any person to whom it is unlawful to make such offer or solicitation in any documents incorporated by reference herein or therein). such jurisdiction.

You should not assume that the information contained in this prospectus, any applicable prospectus supplement or any related free writing prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus, any applicable prospectus supplement or any related free writing prospectus is delivered, or securities are sold, on a later date. We

This prospectus and the selling stockholders have not authorized anyoneinformation incorporated herein by reference contains summaries of certain provisions contained in some of the documents described herein, but reference is made to provide you with any differentthe actual documents for complete information. The selling stockholdersAll of the summaries are offering to sell our securities, and seeking offers to buy, onlyqualified in jurisdictions where offers and sales are permitted.

Proteon Therapeutics, Inc. istheir entirety by the actual documents. Copies of some of the documents referred to herein have been filed, will be filed or will be incorporated by reference as “Proteon”, “the Company”, “we”, “us”,exhibits to the registration statement of which this prospectus is a part, and “our”, unless otherwise specified oryou may obtain copies of those documents as described below under the context indicates otherwise.heading “Where You Can Find More Information.”

Unless otherwise stated, all references in this prospectus to “we,” “us,” “our,” “Protara,” the “Company” and similar designations refer to Protara Therapeutics, Inc. This prospectus contains references to trademarks belonging to other entities. Solely for convenience, trademarks and trade names referred to in this prospectus, including logos, artwork and other visual displays, may appear without the ® or ™ symbols, but such references are not intended to indicate, in any way, that the applicable licensor will not assert, to the fullest extent under applicable law, its rights to these trademarks and trade names. We do not intend our use or display of other companies’ trade names or trademarks to imply a relationship with, or endorsement or sponsorship of us by, any other companies.

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully review the risks and uncertainties described under the heading “Risk Factors” contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in our Annual Report on Form 10-K for the year ended December 31, 2022, as updated by our annual, quarterly and other reports and documents that are incorporated by reference into this prospectus, before deciding whether to purchase any of the securities being registered pursuant to the registration statement of which this prospectus is a part. Each of the risk factors could adversely affect our business, results of operations, financial condition and cash flows, as well as adversely affect the value of an investment in our securities, and the occurrence of any of these risks might cause you to lose all or part of your investment. Additional risks not presently known to us or that we currently believe are immaterial may also significantly impair our business operations.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, including the information incorporated herein by reference, contains, and any prospectus supplement may contain, forward-looking statements. These statements are based on our management’s current beliefs, expectations and assumptions about future events, conditions and results and on information currently available to us. Discussions containing these forward-looking statements may be found, among other places, in the sections titled “Business,” “Risk Factors” and “Management’s Discussion and Analysis of Financial Condition and Results of Operations” incorporated by reference from our most recent Annual Report on Form 10-K and our most recent Quarterly Report on Form 10-Q, before making an investment decision.as well as any amendments thereto, filed with the SEC.

About UsIn some cases, you can identify forward-looking statements by terminology such as “aim,” “anticipate,” “assume,” “believe,” “contemplate,” “continue,” “could,” “design,” “due,” “estimate,” “expect,” “goal,” “intend,” “may,” “objective,” “plan,” “predict,” “positioned,” “potential,” “seek,” “should,” “target,” “will,” “would” or the negative or plural of those terms, and similar expressions intended to identify statements about the future, although not all forward-looking statements contain these words. These forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance or achievements to be materially different from the information expressed or implied by these statements.

Any statements in this prospectus, or incorporated herein by reference, about our expectations, beliefs, plans, objectives, assumptions or future events or performance are not historical facts and are forward-looking statements. Within the meaning of Section 27A of the Securities Act and Section 21E of the Exchange Act these forward-looking statements include statements regarding:

You should refer to the “Risk Factors” section contained in the applicable prospectus supplement and any related free writing prospectus, and under similar headings in the other documents that are incorporated by reference into this prospectus, for a discussion of important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. Given these risks, uncertainties and other factors, many of which are beyond our control, we cannot assure you that the forward-looking statements in this prospectus will prove to be accurate, and you should not place undue reliance on these forward-looking statements. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material. In light of the significant uncertainties in these forward-looking statements, you should not regard these statements as a representation or warranty by us or any other person that we will achieve our objectives and plans in any specified time frame, or at all.

Except as required by law, we assume no obligation to update these forward-looking statements publicly, or to revise any forward-looking statements to reflect events or developments occurring after the date of this prospectus, even if new information becomes available in the future.

USE OF PROCEEDS

We are a late-stage biopharmaceutical company focused onwill retain broad discretion over the developmentuse of novel, first-in-class pharmaceuticals to address the medical needs of patients with kidney and vascular disease. Our product candidate, vonapanitase, is a recombinant human elastase that we are developing to improve vascular access outcomes in patients with chronic kidney disease, or CKD, undergoing or preparing for hemodialysis, a lifesaving treatment that cannot be conducted without a functioning vascular access. We believe the data from our completed Phase 2 and Phase 3 clinical trials of vonapanitase in patients undergoing creation of an arteriovenous fistula support that a one-time, local application of vonapanitase during surgical creation of a radiocephalic fistula for hemodialysis may improve secondary patency (time to fistula abandonment) and fistula use for hemodialysis, thereby improving patient outcomes and reducing the burden on patients and the healthcare system. We are currently conducting our second Phase 3 trial, PATENCY-2, which is evaluating vonapanitase in radiocephalic fistulas, our initial indication. Following our review of the complete data sets from our first Phase 3 trial, PATENCY-1, and discussions with the U.S. Food and Drug Administration, or FDA, we amended the protocol for the PATENCY-2 trial in the first quarter of 2017. The protocol amendment reordered the existing endpoints for this ongoing trial, establishing secondary patency (time to fistula abandonment) and fistula use for hemodialysis as co-primary endpoints. The protocol amendment also increased the planned enrollment for this trial from 300 to 500 patients which we subsequently increased to 600 patients in the second quarter of 2017. The increased sample size of 600 patients for the PATENCY-2 trial provides power to detect the differences observed in the PATENCY-1 trial, with a p-value ≤0.05, for secondary patency (time to fistula abandonment) and fistula use for hemodialysis of 88% and 98%, respectively. We received written confirmation from the FDA that, if PATENCY-2 is successful in showing statistical significance (p≤0.05) on each of the co-primary endpoints, the PATENCY-2 trial together with data from previously completed studies would provide the basis for a Biologics License Application, or BLA, submission as a single pivotal study, in which case no additional studies would need to be conducted. Vonapanitase also received a Breakthrough Therapy designation from the FDA in May 2017 for hemodialysis vascular access. The FDA awards Breakthrough Therapy designations to expedite the development and review of investigational drugs that are intended to treat serious or life-threatening conditions when preliminary clinical evidence indicates that the treatment may offer a substantial improvement over currently available therapies on one or more clinically significant endpoints. We expect to complete enrollment for the PATENCY-2 trial in the first quarter of 2018 and to report top-line data in the first quarter of 2019. If the PATENCY-2 trial is successful, we expect to submit a BLA in 2019.

We commenced business operations in June 2001 and incorporated in March 2006. Our operations to date have been limited to organizing and staffing our company, business planning, raising capital, undertaking preclinical studies and clinical trials of vonapanitase, protecting our intellectual property and providing general and administrative support for these operations. To date, we have not generated any product revenue and have primarily financed our operations through the private placement of our equity securities, business development activities, convertible note financings, and our initial public offering, or IPO, completed in October 2014.

As of March 31, 2017, we had received an aggregate of $174.5 million in net proceeds comprised of $94.0 million from the issuance of private equity securities, $7.7 million from the issuance of convertible notes, $10.0 million from business development activities, $0.2 million from government grants, $62.5 million from our IPO and $0.1 million from the sale of common stock under our at-the-market, or ATM, program with Cowen and Company, LLC.

We have never been profitable and have incurred net losses in each year since inception. As of March 31, 2017, we had an accumulated deficit of $166.3 million and our net loss for the three months ended March 31, 2017 was $6.5 million. We expect to incur significant expenses and increasing operating losses for the foreseeable future. We expect our research and development expenses to increase as we continue the clinical trials of, and seek regulatory approval for, vonapanitase. If we obtain regulatory approval for vonapanitase, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Furthermore, we expect that our general and administrative costs will increase as we grow and operate as a public company. As a result, we will need to generate significant revenue if we are to achieve profitability, and we may never be able to do so.

Prior to the sale of our Series A Convertible Preferred Stock, we believed that our cash and cash equivalents and available-for-sale investments as of March 31, 2017 would be sufficient to fund our operating expenses and capital expenditure requirements into the third quarter of 2018. We closed our $22 million Series A Convertible Preferred Stock transaction on August 2, 2017 and, when including net proceeds from the sale of our Series A Convertible Preferred Stock alongthe securities offered hereby. Except as described in any applicable prospectus supplement or in any related free writing prospectus that we may authorize to be provided to you in connection with our cash and cash equivalents and available-for-sale investments as of March 31, 2017, we believe we will have sufficient funds to cover our operating expenses and capital expenditure requirements into the fourth quarter of 2019, thus allowing us to complete enrollment of patients in our second Phase 3 trial of vonapanitase in radiocephalic fistulas, to fund our chemistry, manufacturing and controls, or CMC, activities and to obtain results from our second Phase 3 trial.

We do not expect to generate revenue from product sales unless and until we successfully complete development and obtain regulatory approval for vonapanitase, which we expect will take a number of years and is subject to significant uncertainty. We have no manufacturing facilities and all of our manufacturing activities are contracted out to third parties. Additionally,specific offering, we currently intend to use third-party clinical research organizations, or CROs, to carry out our clinical development activities and we do not yet have a sales organization. If we obtain regulatory approval for vonapanitase, we expect to incur significant commercialization expenses related to product sales, marketing, manufacturing and distribution. Accordingly, we may seek to further fund our operations through public or private equity or debt financings or other sources, including strategic collaborations. We may, however, be unable to raise additional funds or enter into such other arrangements when needed on favorable terms or at all. Our failure to raise additional capital or enter into such other arrangements as and when needed would have a negative impact on our financial condition and our ability to develop vonapanitase or any additional product candidates, if developed.

Recent Events

Private Placement

On June 22, 2017, we entered into a securities purchase agreement (the “Purchase Agreement”) with a syndicate of current and new institutional investors (each individually, an “Investor” and, collectively, the “Investors”), led by a fund affiliated with Deerfield Management Company, L.P. (“Deerfield”), pursuant to which we agreed to issue and sell to the Investors an aggregate of 22,000 shares (the “Preferred Shares”) of the Company’s Series A Convertible Preferred Stock, par value $0.001 per share (the “Series A Preferred Stock” and such sale of the Series A Preferred Stock, the “Transaction”), for a purchase price of $1,000 per share, or an aggregate purchase price of $22.0 million, all upon the terms and conditions set forth in the Purchase Agreement. In the Purchase Agreement, we made customary representations and warranties to the Investors relating to the Company, our business and the issuance of the securities at the closing. The representations and warranties of the respective parties to the Purchase Agreement will survive the closing of the Transaction. Consummation of the Transaction was subject to customary closing conditions, including (i) approval by the Company’s stockholders and (ii) minimum grossnet proceeds received by the Company from the sale of the securities offered hereby, if any, for general corporate purposes, including research and development expenses, general and administrative expenses, sales and marketing expenses, capital expenditures, which may include costs of funding future license agreements, acquisitions, and working capital or for any other purpose we describe in the applicable prospectus supplement. We will set forth in the applicable prospectus supplement or free writing prospectus our intended use for the net proceeds received from the sale of any securities sold pursuant to the prospectus supplement or free writing prospectus. Pending the use of net proceeds, we plan to invest the net proceeds in short- and intermediate-term interest-bearing obligations, investment-grade securities, certificates of deposit or government securities.

DESCRIPTION OF CAPITAL STOCK

The following summary description of our capital stock is based on the provisions of our sixth amended and restated certificate of incorporation, as amended from time to time, our second amended and restated bylaws, our certificate of designation of preferences, rights and limitations of Series 1 Convertible Non-Voting Preferred SharesStock, as amended from time to all Investors attime, and the closingapplicable provisions of the Transaction equalDelaware General Corporation Law. This information is qualified entirely by reference to no less than $18,000,000. We also agreed to indemnify the Investors for certain breachesapplicable provisions of our representationssixth amended and warranties in certain circumstances. We received stockholder approval forrestated certificate of incorporation, as amended from time to time, our second amended and restated bylaws, our certificate of designation of preferences, rights and limitations of Series 1 Convertible Non-Voting Preferred Stock, as amended from time to time, and the TransactionDelaware General Corporation Law. For information on July 31, 2017 at a special meetinghow to obtain copies of our stockholderssixth amended and restated certificate of incorporation, as amended from time to time, our second amended and restated bylaws, our certificate of designation of preferences, rights and limitations of Series 1 Convertible Non-Voting Preferred Stock, as amended from time to time, each of which are exhibits to the Transaction closed on August 2, 2017.registration statement of which this prospectus is a part, see “Where You Can Find Additional Information.” We refer in this section to our sixth amended and restated certificate of incorporation, as amended from time to time, and our second amended and restated bylaws as our “certificate of incorporation” and our “bylaws”, respectively.

The following holders, or affiliatesGeneral

Our authorized capital stock consists of 110,000,000 shares, all with a par value of $0.001 per share, of which 100,000,000 shares are designated as common stock and 10,000,000 shares are designated as preferred stock. As of November 2, 2023, we had 11,364,903 shares of common stock and 7,991 shares of Series 1 Preferred Stock outstanding.

Common Stock

Voting Rights

Each holder of our common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Our stockholders do not have cumulative voting rights in the election of directors. An election of directors by our stockholders shall be determined by a plurality of votes cast by the stockholders entitled to vote on the election.

Dividends

Subject to preferences that may be applicable to any then outstanding preferred stock, holders of more than 5%our common stock are entitled to receive dividends, if any, as may be declared from time to time by the board of our Common Stock have executed the Purchase Agreement as investors: Abingworth Bioventures VI, LP, a fund affiliated with Deerfield Management Company, L.P., Intersouth Partners VI, L.P., Pharmstandard International S.A., Skyline Venture Partners Qualified Purchaser Fund IV, LP, RA Capital and related funds, and TVM Capital and relateddirectors out of legally available funds. Additional information regarding ownership is described below in “Selling Stockholders.”

Liquidation

In connection with the Transaction, concurrently withevent of our liquidation, dissolution or winding up, holders of our common stock will be entitled to share ratably in the executionnet assets legally available for distribution to stockholders after the payment of all of our debts and deliveryother liabilities and the satisfaction of the Purchase Agreement, and as an inducementany liquidation preference granted to the Investors to enter into the Purchase Agreement, the Companyholders of any then outstanding shares of preferred stock.

Rights and certain stockholders of the Company entered into a Fifth Amended and Restated Investors’ Rights Agreement, dated as of June 22, 2017 (the “Fifth IRA”), pursuant to which such stockholders agreed to certain limitations on the registration rights provided for under that certain Fourth Amended and Restated Investors’ Rights Agreement, dated as of May 13, 2014. The Fifth IRA became effective upon the closing of the Transaction.Preferences

Holders of common stock have no preemptive, conversion or subscription rights and there are no redemption or sinking fund provisions applicable to the common stock. The rights, preferences and privileges of the 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 in the future.

Preferred Stock

Under our certificate of incorporation, our board of directors has the authority, without further action by stockholders, to designate up to 10,000,000 shares of preferred stock in one or more series and to fix or alter, from time to time, the powers, designations, preferences, and relative, participating, optional, or other special rights, if any, and such qualifications and restrictions, if any, of any series of preferred stock, including dividend rights, dividend rate, conversion rights, voting rights, rights and terms of redemption (including sinking fund provisions), redemption price or prices, and the liquidation preference of any wholly unissued series of preferred stock, any or all of which may be greater than the rights of the common stock, and to establish the number of shares constituting any such series. Our board of directors has designated 8,028 shares of preferred stock as Series A1 Preferred Stock.

Our board of directors will fix the rights, preferences, privileges, qualifications and restrictions of the preferred stock of each series that we sell under this prospectus and any applicable prospectus supplements in the certificate of designation relating to each such series. We will incorporate by reference as an exhibit to the registration statement of which this prospectus is a part or as an exhibit to one or more Current Reports on Form 8-K, the form of any certificate of designation that describes the terms of the series of preferred stock we are offering before the issuance of the related series of preferred stock. This description will include:

If we issue and sell shares of preferred stock pursuant to this prospectus, together with any applicable prospectus supplement or free writing prospectus, the shares will be fully paid and non-assessable.

The laws of the state of Delaware, the state of our incorporation, provide that the holders of preferred stock will have the right to vote separately, as a class, on any proposal involving fundamental changes in the rights of holders of such preferred stock. This right is in addition to any voting rights that may be provided for in the applicable certificate of designation.

The issuance of preferred stock could adversely affect the voting power, conversion or other rights of holders of common stock and reduce the likelihood that common stockholders will receive dividend payments and payments upon liquidation. Preferred stock could be issued quickly with terms designed to delay, deter or prevent a change in control of our company or make removal of management more difficult. Additionally, the issuance of preferred stock may have the effect of decreasing the market price of our common stock.

Series 1 Convertible Non-Voting Preferred Stock

September 2019 Offering

On September 23, 2019, we entered into a subscription agreement, or the Subscription Agreement, with certain institutional investors, or the Purchasers, providing for the issuance and sale of 1,896,888 shares of common stock and 3,879,356 shares of Series 1 Preferred Stock are set forth in the Certificatefor an aggregate purchase price of Designation of Preferences, Rights and Limitations of Series A Convertible Preferred Stock (“Certificate of Designation”), which we filed with the Secretary of State of the State of Delawareapproximately $40.5 million. The Subscription Agreement was subsequently amended by a First Amendment to Subscription Agreement on August 1, 2017. November 19, 2019.

Each share of Series A1 Preferred Stock is convertible, into approximately 1,005 sharesat any time at the option of our common stock, atthe holder thereof, a conversion rate equal to the stated value of $7,011.47 per share divided by an initial conversion price of $0.9949$7.01 per share, in each case subject to adjustment for any stock splits, stock dividends and similar events, at any time at the option ofand further subject to a 9.99% blocker provision. Upon written notice to us, the holder provided that any conversion of Series A Preferred Stock by a holder into shares of Common Stock would be prohibited if, as a result ofmay from time to time increase or decrease such conversion, the holder, together with its affiliates andlimitation to any other person or entity whose beneficial ownership of our common stock would be aggregated with such holder’s for purposes of Section 13(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), would beneficially own more than 9.985% of the total number of shares of our common stock issued and outstanding after giving effect to such conversion (the “Blocker”). For purposes of clarity, the shares of common stock underlying any holder’s shares of Series A Preferred Stockpercentage not in excess of the Blocker shall not be deemed19.99% specified in such notice. Each share of Series 1 Preferred Stock is entitled to be beneficially owned by such holder for any purpose, including for purposesa preference of Section 13(d) or Rule 16a-1(a)(1)$10.00 per share upon liquidation of the Exchange Act. The Blocker may notCompany, and thereafter will share ratably in any distributions or payments on an as-converted basis with the holders of common stock. In addition, upon the occurrence of certain transactions that involve the merger or consolidation of the Company, an exchange or tender offer, a sale of all or substantially all of the assets of the Company or a reclassification of its common stock, each share of Series 1 Preferred Stock will be waivedconvertible into the kind and shall apply to any successoramount of securities, cash and/or other property that the holder of shares of Series A Preferred Stock.

For purposes of the Blocker, the aggregate number of shares of common stock beneficially owned by a holder and its Attribution Parties (as defined below) shall include the number of shares of common stock held by such holder and its Attribution Parties plus the number of shares of common stock issuable upon conversion of one share of Series 1 Preferred Stock would receive in connection with such transaction. Except as provided in the Certificate of Designation or as required by law, the shares of Series A1 Preferred Stock have no voting rights.

Pursuant to the Subscription Agreement, certain holders of Series 1 Preferred Stock have preemptive rights to participate pro rata in future equity financings of the Company, subject to certain exceptions and limitations. In addition, the lead Purchaser has the right (but not the obligation) to appoint up to two directors to our board of directors and one other Purchaser has the right (but not the obligation) to appoint one director to our board of directors, in each case subject to requirements related to holding minimum amounts of our equity securities. In addition, at any time when it does not have a designee serving on the board of directors, each of these Purchasers has a right to designate an individual to be present and participate in a non-voting capacity in all meetings of our board of directors and committees of the board. Further, we have also agreed not to take certain actions related to the business without the consent of the lead Purchaser for so long as such lead Purchaser continues to hold a minimum amount of the Series 1 Preferred Stock purchased under the Subscription Agreement. These actions include (a) liquidating, dissolving or winding-up the affairs of the Company; (b) any merger, consolidation or other Fundamental Transaction (defined in the Subscription Agreement); (c) amendments to our certificate of incorporation or bylaws in a manner that adversely effects the Series 1 Preferred Stock and that is disproportionate to the effect on any other class or series of capital stock; (d) material changes to the principal business of the Company; (e) purchases, redemptions or the payment of dividends on any capital stock (subject to certain exceptions); (f) the sale, assignment, license or pledge of TARA-002; and (g) transactions involving assets of the Company with respectan aggregate value over $2.5 million.

Concurrently with the execution of the Subscription Agreement, we entered into a registration rights agreement, or the Registration Rights Agreement, dated September 23, 2019, with the Purchasers. Pursuant to which the determination is being made, but shall excludeterms of the Registration Rights Agreement, we prepared and filed a registration statement on Form S-3 on January 30, 2020 for the purposes of registering the resale of the shares of common stock which would be issuable upon (i) conversion ofissued pursuant to the remaining, unconverted portion ofSubscription Agreement and the shares of Series A Preferred Stock beneficially owned by such holder or any of its Attribution Parties and (ii) exercise or conversion of the unexercised or unconverted portion of any other securities of the Company beneficially owned by such holder or any of its Attribution Parties, subject to certain limitations on conversion or exercise. For purposes of the Blocker, in determining the number of outstanding shares of common stock a holder may rely onissuable upon conversion of the numberSeries 1 Preferred Stock issued pursuant to the Subscription Agreement. Additionally, pursuant to the Subscription Agreement, if at any time after 180 days following the date of outstanding shares as reflected in (1)closing of the Company’s most recent quarterly report on Form 10-Q or annual report on Form 10-K, as the case may be, (2) a more recent public announcement by the Company or (3) any other notice by the Company or the transfer agent for theissuance and sale of Series 1 Preferred Stock and common stock setting forth the number of shares of common stock outstanding.

 The following defined terms are set forth in the Certificate of Designation:

“Attribution Parties” means, with respect to any holder, collectively, any of such Holder’s Affiliates (as defined below), any Persons (as defined below) acting as a “group” together with such Holder with respectpursuant to the common stock for purposes of Section 13(d) ofSubscription Agreement, either the Exchange Act, and any other Persons whose beneficial ownership of the common stock would be aggregated with such Holder’s for purposes of Section 13(d) of the Exchange Act.

“Affiliate” means any Person (as hereinafter defined)lead Purchaser or another Purchaser determines that directly or indirectly through one or more intermediaries, controls or is controlled by or is under common control with such Person, as such terms are used in and construed under Rule 144 under the Securities Act (“Rule 144”). With respect to a Holder, any investment fund or managed account that is managed on a discretionary basis by the same investment manager as such Holder willit may be deemed to be an Affiliate of such Holder. As used in this definition of “Affiliate,” the term “control” means the possession, directly or indirectly,“affiliate” of the power to direct or causeCompany within the directionmeaning of Rule 144 of the management and policies ofSecurities Act, we shall enter into a Person, whether through ownership of voting securities or partnership or other ownership interest, by contract, or otherwise.

“Person” means an individual, a limited liability company, a partnership, a joint venture, a corporation, a trust, an unincorporated organization or a government or any department or agency thereof or any other legal entity.

In the event that the issuance of shares of common stock to any holder upon the conversion of any of such holder’s shares of Series A Preferred Stock results in such holder and its Attribution Parties being deemed to beneficially own, in the aggregate, a number of shares of common stock that exceeds the Blocker, the issuance of that number of shares so issued in excess of the Blocker (the “Excess Shares”), and the conversion of shares of Series A Preferred Stock resulting in such issuance, shall be deemed null and void and shall be cancelled ab initio, such holder shall not have the power to vote or to transfer the Excess Shares, and the shares of Series A Preferred Stock as to which the conversion was voided shall remain outstanding and continue to be held by such holder. As soon as reasonably practicable after such issuance and conversion have been deemed null and void, the Company shall return to such holder certificates representing the number of shares of Series A Preferred Stock corresponding to the voided issuance and conversion (to the extent such shares of Series A Preferred Stock were surrendered to the Company).

Prior to the first date (the “Preference Termination Date”) that the volume-weighted average price per share of common stock for each of the trading days during any twenty consecutive trading days ending on or at any time after the one year anniversary of the approval of the Company’s biologics license application for the Company’s product vonapanitase by the United States Food and Drug Administration is greater than 200% of the conversion price, the holders of a majority of the outstanding shares of Series A Preferred Stock will be entitled to elect one (1) member of the Board (the “Series A Director”). On August 2, 2017, the holders of a majority of the outstanding shares of Series A Preferred Stock elected Jonathan Leff to serve as the Series A Director. Mr. Leff is a Partner at Deerfield Management Company, L.P., the investment manager of Deerfield Private Design Fund IV, L.P., serving on the Private Transactions team and as Chairman of the Deerfield Institute.

The Series A Director is entitled to the same compensation, the same indemnification and the same director and officer insurance in connectionregistration rights agreement with such Series A Director’s service as a director as all other non-employee members of the Board, and the Series A Director is entitled to reimbursement for documented, reasonable out-of-pocket expenses incurred in attending meetings of the Board and any committees thereof, to the same extent as all other non-employee members of the Board. In addition, the Series A Director is entitled to the same information regarding the Company and its subsidiaries in connection with the Series A Director’s service as a director as all other members of the Board. Further, the Series A Director will hold office until the following year’s annual meeting of the Company’s stockholders and until his or her successor is duly elected or qualified by the written consent of the holders of a majority of the outstanding shares of Series A Preferred Stock or until his or her earlier death, incapacity, resignation or removal. Such Series A Director may be removed from office, with or without cause, upon the written consent of the holders of a majority of the outstanding shares of Series A Preferred Stock, and the holders of a majority of the outstanding shares of Series A Preferred Stock shall have the power to fill, by written consent, any vacancy caused by the resignation, death or removal of such Series A Director. For purposes of clarity, the Series A Director shall not be classified with the remaining members of the Board of Directors.

Contemporaneously with the closing of the Transaction, we entered into a Registration Rights Agreement with the Investors (the “Registration Rights Agreement”). Pursuant to the Registration Rights Agreement, the Investors are entitled to certain shelf and “piggyback” registration rights with respect to the Conversion Shares, subject to the limitations set forth in the Registration Rights Agreement. In addition, pursuant to the Registration Rights Agreement, we agreedPurchaser requiring us to file a registration statement on Form S-3 pursuant to a demand by such Purchaser in connection with the SEC, within 20 days afterresale of such Purchaser’s shares of common stock.

The preceding summaries do not purport to be complete and are qualified in their entirety by reference to the closingCertificate of Designation for the Series 1 Preferred Stock, the Registration Rights Agreement and the Subscription Agreement, as applicable, copies of which are attached hereto as Exhibits 3.5, 4.5 and 10.1, respectively, and which are incorporated herein by reference.

September 2020 Offering

On September 24, 2020, we issued and sold in an underwritten public offering an additional 4,148 shares of our Series 1 Preferred Stock at an offering price of $16,873.54 per share, for gross and net proceeds of approximately $70.0 million and $66.3 million, respectively.

Delaware Anti-Takeover Law and Provisions of Our Certificate of Incorporation, as amended, and Bylaws, as amended

Our certificate of incorporation and our bylaws contain certain provisions that could have the effect of delaying, deterring or preventing another party from acquiring control of us, and therefore could adversely affect the market price of our common stock. These provisions and certain provisions of Delaware General Corporation Law, or the DGCL, which are summarized below, may also discourage coercive takeover practices and inadequate takeover bids, and are designed, in part, to encourage persons seeking to acquire control of us to negotiate first with our board of directors. We believe that the benefits of increased protection of our potential ability to negotiate more favorable terms with an unfriendly or unsolicited acquirer outweigh the disadvantages of potentially discouraging a proposal to acquire us.

Delaware Anti-Takeover Law

We are subject to Section 203 of the Transaction,DGCL, or Section 203. Section 203 generally prohibits a public Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a period of three years following the time that such stockholder became an interested stockholder, unless:

Section 203 defines a business combination to register for resaleinclude:

In general, Section 203 defines an interested stockholder as any entity or person beneficially owning 15% or more of the Conversion Sharesoutstanding voting stock of the corporation and any entity or person affiliated with or controlling or controlled by the entity or person.

Certificate of Incorporation and Bylaws

Our certificate of incorporation and bylaws contain certain provisions that are issuable uponintended to enhance the conversionlikelihood of continuity and stability in the composition of the Preferredboard of directors and which may have the effect of delaying, deferring or preventing a future takeover or change in control unless such takeover or change in control is approved by the board of directors. In addition, the authorization of undesignated preferred stock makes it possible for our board of directors to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change our control. These provisions include:

Classified board of directors

Our certificate of incorporation provides that the board of directors is divided into three classes of directors, with the classes as nearly equal in number as possible. Any additional directorships resulting from an increase in the number of directors will be apportioned by the board of directors among the three classes. The classification of directors will have the effect of making it more difficult for stockholders to change the composition of the board of directors.

Our certificate of incorporation provides that, subject to any rights of holders of preferred stock to elect additional directors under specified circumstances, the number of directors will be fixed exclusively pursuant to a resolution adopted by the board of directors. Any additional directorships resulting from an increase in the number of directors will be distributed among the three classes so that, as nearly as possible, each class shall consist of one third of the board of directors.

Action by Written Consent; Special Meetings of Stockholders

Our certificate of incorporation provides that stockholder action can be taken only at an annual or special meeting of stockholders and cannot be taken by written consent in lieu of a meeting. Our certificate of incorporation and bylaws also provide that, except as otherwise required by law, special meetings of the stockholders can be called only by or at the direction of the board of directors pursuant to a resolution adopted by a majority of the total number of directors. Except as described above, stockholders will not be permitted to call a special meeting or to require the board of directors to call a special meeting.

Removal of Directors

Our certificate of incorporation provides that our directors may be removed only for cause by the affirmative vote of at least 75% of the voting power of our outstanding shares of capital stock, voting together as a single class and entitled to vote in the election of directors. This requirement of a supermajority vote to remove directors could enable a minority of our stockholders to prevent a change in the composition of the board of directors.

Advance Notice Procedures

Our bylaws include an advance notice procedure for stockholder proposals to be brought before an annual meeting of our stockholders, including proposed nominations of persons for election to the board of directors. Stockholders at an annual meeting will only be able to consider proposals or nominations specified in the notice of meeting or brought before the meeting by or at the direction of the board of directors or by a stockholder who was a stockholder of record on the record date for the meeting, who is entitled to vote at the meeting and who has given our Secretary timely written notice, in proper form, of the stockholder’s intention to bring that business before the meeting. Although the bylaws do not give the board of directors the power to approve or disapprove stockholder nominations of candidates or proposals regarding other business to be conducted at a special or annual meeting, the bylaws may have the effect of precluding the conduct of certain business at a meeting if the proper procedures are not followed or may discourage or deter a potential acquirer from conducting a solicitation of proxies to elect its own slate of directors or otherwise attempting to obtain control of us.

Super Majority Approval Requirements

The Delaware General Corporation Law generally provides that the affirmative vote of a majority of the shares entitled to vote on any matter is required to amend a corporation’s certificate of incorporation or bylaws, unless either a corporation’s certificate of incorporation or bylaws requires a greater percentage. Our certificate of incorporation and bylaws provide that the affirmative vote of holders of at least 75% of the outstanding shares of capital stock, voting together as a single class and entitled to vote in the election of directors will be required to amend, alter, change or repeal the bylaws and certain portions of the certificate of incorporation. This requirement of a supermajority vote to approve amendments to our bylaws could enable a minority of our stockholders to exercise veto power over any such amendments.

Authorized but Unissued Shares issued at closing, and any additional

Our authorized but unissued shares of common stock aswill be available for future issuance without stockholder approval. These additional shares may become issuable with respectbe utilized for a variety of corporate purposes, including future public offerings to such securities as a resultraise additional capital, corporate acquisitions and employee benefit plans. The existence of stock splits, stock dividends or similar transactions (the “Registrable Securities”), and to maintain the effectiveness of such registration statement(s) until all theauthorized but unissued shares of common stock could render more difficult or discourage an attempt to obtain control of a majority of our common stock by means of a proxy contest, tender offer, merger or otherwise.

Exclusive Forum

Our certificate of incorporation provides that, subject to limited exceptions, the state or federal courts located in the State of Delaware will be the sole and exclusive forum for (i) any derivative action or proceeding brought on our behalf, (ii) any action asserting a claim of breach of a fiduciary duty owed by any of our directors, officers or other employees to us or our stockholders, (iii) any action asserting a claim against us arising pursuant to any provision of the Delaware General Corporation Law, our certificate of incorporation or our bylaws, or (iv) any other action asserting a claim against our that is governed by the internal affairs doctrine; provided, that these provisions will not apply to actions or proceedings brought to enforce a duty or liability created by the Securities Act, the Securities Exchange Act of 1934, as amended, or the Exchange Act, or any other claim for which the federal courts have exclusive jurisdiction. Any person or entity purchasing or otherwise acquiring any interest in shares of our capital stock shall be deemed to have notice of and to have consented to the provisions of our certificate of incorporation described above. Although we believe these provisions benefit us by providing increased consistency in the application of Delaware law for the specified types of actions and proceedings, the provisions may have the effect of discouraging lawsuits against our directors and officers. The enforceability of similar choice of forum provisions in other companies’ certificates of incorporation has been challenged in legal proceedings, and it is possible that, in connection with one or more actions or proceedings described above, a court could find the choice of forum provisions contained in our certificate of incorporation to be inapplicable or unenforceable.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Computershare Trust Company, N.A.

Listing

Our common stock is listed on the Nasdaq Capital Market under the symbol “TARA.”

DESCRIPTION OF DEBT SECURITIES

We may issue debt securities from time to time, in one or more series, as either senior or subordinated debt or as senior or subordinated convertible debt. While the terms we have summarized below will apply generally to any debt securities that we may offer under this prospectus, we will describe the particular terms of any debt securities that we may offer in more detail in the applicable prospectus supplement. The terms of any debt securities offered under a prospectus supplement may differ from the terms described below. Unless the context requires otherwise, whenever we refer to the indenture, we also are referring to any supplemental indentures that specify the terms of a particular series of debt securities.

We will issue the debt securities under the indenture that we will enter into with the trustee named in the indenture. The indenture will be qualified under the Trust Indenture Act of 1939, as amended, or the Trust Indenture Act. We have filed the form of indenture as an exhibit to the registration statement of which this prospectus is a part, and supplemental indentures and forms of debt securities containing the terms of the debt securities being offered will be filed as exhibits to the registration statement of which this prospectus is a part, or will be incorporated by reference from, reports that we file with the SEC.

The following summary of material provisions of the debt securities and the indenture is subject to, and qualified in its entirety by reference to, all of the provisions of the indenture applicable to a particular series of debt securities. We urge you to read the applicable prospectus supplements and any related free writing prospectuses related to the debt securities that we may offer under this prospectus, as well as the complete indenture that contains the terms of the debt securities.

General

The indenture does not limit the amount of debt securities that we may issue. It provides that we may issue debt securities up to the principal amount that we may authorize and may be in any currency or currency unit that we may designate. Except for the limitations on consolidation, merger and sale of all or substantially all of our assets contained in the indenture, the terms of the indenture do not contain any covenants or other provisions designed to give holders of any debt securities protection against changes in our operations, financial condition or transactions involving us.

We may issue the debt securities issued under the indenture as “discount securities,” which means they may be sold at a discount below their stated principal amount. These debt securities, as well as other debt securities that are not issued at a discount, may be issued with “original issue discount,” or OID, for U.S. federal income tax purposes because of interest payment and other characteristics or terms of the debt securities. Material U.S. federal income tax considerations applicable to debt securities issued with OID will be described in more detail in any applicable prospectus supplement.

We will describe in the applicable prospectus supplement the terms of the series of debt securities being offered, including:

Conversion or Exchange Rights

We will set forth in the applicable prospectus supplement the terms on which a series of debt securities may be convertible into or exchangeable for our common stock or our other securities. We will include provisions as to settlement upon conversion or exchange and whether conversion or exchange is mandatory, at the option of the holder or at our option. We may include provisions pursuant to which the number of shares of our common stock or our other securities that the holders of the series of debt securities receive would be subject to adjustment.

Consolidation, Merger or Sale

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the indenture will not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise dispose of our assets as an entirety or substantially as an entirety. However, any successor to or acquirer of such assets (other than any subsidiary of ours) must assume all of our obligations under the indenture or the debt securities, as appropriate.

Events of Default under the Indenture

Unless we provide otherwise in the prospectus supplement applicable to a particular series of debt securities, the following are events of default under the indenture with respect to any series of debt securities that we may issue:

If an event of default with respect to debt securities of any series occurs and is continuing, other than an event of default specified in the last bullet point above, the trustee or the holders of at least 25% in aggregate principal amount of the outstanding debt securities of that series, by notice to us in writing, and to the trustee if notice is given by such holders, may declare the unpaid principal of, premium, if any, and accrued interest, if any, due and payable immediately. If an event of default specified in the last bullet point above occurs with respect to us, the principal amount of and accrued interest, if any, of each issue of debt securities then outstanding shall be due and payable without any notice or other action on the part of the trustee or any holder.

The holders of a majority in principal amount of the outstanding debt securities of an affected series may waive any default or event of default with respect to the series and its consequences, except defaults or events of default regarding payment of principal, premium, if any, or interest, unless we have cured the default or event of default in accordance with the Registration Statementindenture. Any waiver shall cure the default or event of default.

Subject to the terms of the indenture, if an event of default under an indenture shall occur and be continuing, the trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any of the holders of the applicable series of debt securities, unless such holders have offered the trustee reasonable indemnity. 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, provided that:

A holder of the debt securities of any series will have the right to institute a proceeding under the indenture or to appoint a receiver or trustee, or to seek other remedies only if:

These limitations do not apply to a suit instituted by a holder of debt securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statements with the trustee regarding our compliance with specified covenants in the indenture.

Modification of Indenture; Waiver

We and the trustee may change an indenture without the consent of any holders with respect to specific matters:

Discharge

Each indenture provides that we can elect to be discharged from our obligations with respect to one or more series of debt securities, except for specified obligations, including obligations to:

In order to exercise our rights to be discharged, we must deposit with the trustee money or government obligations sufficient to pay all the principal of, any premium, if any, and interest on, the debt securities of the series on the dates payments are due.

Form, Exchange and Transfer

We will issue the debt securities of each series only in fully registered form without coupons and, unless we provide otherwise in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indenture provides that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities that will be deposited with, or on behalf of, The Depository Trust Company, or DTC, or another depositary named by us and identified in the applicable prospectus supplement with respect to that series. To the extent the debt securities of a series are issued in global form and as book-entry, a description of terms relating to any book-entry securities will be set forth in the applicable prospectus supplement.

At the option of the holder, subject to the terms of the indenture and the limitations applicable to global securities described in the applicable prospectus supplement, the holder of the debt securities of any series can exchange the debt securities for other debt securities of the same series, in any authorized denomination and of like tenor and aggregate principal amount.

Subject to the terms of the indenture and the limitations applicable to global securities set forth in the applicable prospectus supplement, holders of the debt securities may present the debt securities for exchange or for registration of transfer, duly endorsed or with the form of transfer endorsed thereon duly executed if so required by us or the security registrar, at the office of the security registrar or at the office of any transfer agent designated by us for this purpose. Unless otherwise provided in the debt securities that the holder presents for transfer or exchange, we will impose no service charge for any registration of transfer or exchange, but we may require payment of any taxes or other governmental charges.

We will name in the applicable prospectus supplement the security registrar, and any transfer agent in addition to the security registrar, that we initially designate for any debt securities. We may at any time designate additional transfer agents or rescind the designation of any transfer agent or approve a change in the office through which any transfer agent acts, except that we will be required to maintain a transfer agent in each place of payment for the debt securities of each series.

If we elect to redeem the debt securities of any series, we will not be required to:

Information Concerning the Trustee

The trustee, other than during the occurrence and continuance of an event of default under an indenture, undertakes to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the trustee must use the same degree of care as a prudent person would exercise or use in the conduct of his or her own affairs. Subject to this provision, the trustee is under no obligation to exercise any of the powers given it by the indenture at the request of any holder of debt securities unless it is offered reasonable security and indemnity against the costs, expenses and liabilities that it might incur.

Payment and Paying Agents

Unless we otherwise indicate in the applicable prospectus supplement, we will make payment of the interest on any debt securities on any interest payment date to the person in whose name the debt securities, or one or more predecessor securities, are registered at the close of business on the regular record date for the interest.

We will pay principal of and any premium and interest on the debt securities of a particular series at the office of the paying agents designated by us, except that unless we otherwise indicate in the applicable prospectus supplement, we will make interest payments by check that we will mail to the holder or by wire transfer to certain holders. Unless we otherwise indicate in the applicable prospectus supplement, we will designate the corporate trust office of the trustee as our sole paying agent for payments with respect to debt securities of each series. We will name in the applicable prospectus supplement any other paying agents that we initially designate for the debt securities of a particular series. We will maintain a paying agent in each place of payment for the debt securities of a particular series.

All money we pay to a paying agent or the trustee for the payment of the principal of or any premium or interest on any debt securities that remains unclaimed at the end of two years after such principal, premium or interest has become due and payable will be repaid to us, and the holder of the debt security thereafter may look only to us for payment thereof.

Governing Law

The indenture and the debt securities will be governed by and construed in accordance with the internal laws of the State of New York, except to the extent that the Trust Indenture Act is applicable.

DESCRIPTION OF WARRANTS

The following description, together with the additional information we may include in any applicable prospectus supplements and free writing prospectuses, summarizes the material terms and provisions of the warrants that we may offer under this prospectus, which may consist of warrants to purchase common stock, preferred stock or debt securities and may be issued in one or more series. Warrants may be issued independently or together with common stock, preferred stock or debt securities offered by any prospectus supplement, and may be attached to or separate from those securities. While the terms we have summarized below will apply generally to any warrants that we may offer under this prospectus, we will describe the particular terms of any series of warrants that we may offer in more detail in the applicable prospectus supplement and any applicable free writing prospectus. The terms of any warrants offered under a prospectus supplement may differ from the terms described below. However, no prospectus supplement will fundamentally change the terms that are set forth in this prospectus or offer a security that is not registered and described in this prospectus at the time of its effectiveness.

We have filed forms of the warrant agreements as exhibits to the registration statement of which this prospectus is a part. We will file as exhibits to the registration statement of which this prospectus is a part, or will incorporate by reference from reports that we file with the SEC, the form of warrant agreement, if any, including a form of warrant certificate, that describes the terms of the particular series of warrants we are offering. The following summaries of material provisions of the warrants and the 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 the particular series of warrants that we may offer under this prospectus. We urge you to read the applicable prospectus supplements related to the particular series of warrants that we may offer under this prospectus, as well as any related free writing prospectuses, and the complete warrant agreements and warrant certificates that contain the terms of the warrants.

General

In the applicable prospectus supplement, we will describe the terms of the series of warrants being offered, including, to the extent applicable:

Before exercising their warrants, holders of warrants will not have any of the rights of holders of the securities purchasable upon such exercise, including:

Exercise of Warrants

Each warrant will entitle the holder to purchase the securities that we specify in the applicable prospectus supplement at the exercise price that we describe 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.

Unless we otherwise specify in the applicable prospectus supplement, holders of the warrants may exercise the warrants by delivering the warrant certificate representing the warrants to be exercised together with specified information, and paying the required amount to the warrant agent in immediately available funds, as provided in the applicable prospectus supplement. We will set forth on the reverse side of the warrant certificate and in the applicable prospectus supplement the information that the holder of the warrant will be required to deliver to the warrant agent in connection with the exercise of the warrant.

On receipt of payment and the warrant or warrant certificate, as applicable, properly completed and duly executed at the corporate trust office of the warrant agent, if any, or any other office, including ours, indicated in the prospectus supplement, we will, as soon as practicable, issue and deliver the securities purchasable on such exercise. If less than all of the warrants (or the warrants represented by such warrant certificate) are exercised, a new warrant or a new warrant certificate, as applicable, will be issued for the remaining warrants.

Governing Law

Unless we provide otherwise in the applicable prospectus supplement, the warrants and warrant agreements, and any claim, controversy or dispute arising under or related to the warrants or warrant agreements, will be governed by and construed in accordance with the laws of the State of New York.

Enforceability of Rights by Holders of Warrants

Each warrant agent, if any, will act solely as our agent under the applicable warrant agreement and will not assume any obligation or relationship of agency or trust with any holder of any warrant. A single bank or trust company may act as warrant agent for more than one issue of warrants. A warrant agent will have no duty or responsibility in case of any default by us under the applicable warrant agreement or warrant, including any duty or responsibility to initiate any proceedings at law or otherwise, or to make any demand upon us. Any holder of a warrant may, without the consent of the related warrant agent or the holder of any other warrant, enforce by appropriate legal action its right to exercise, and receive the securities purchasable upon exercise of, its warrants.

LEGAL OWNERSHIP OF SECURITIES

We can issue securities in registered form or in the form of one or more global securities. We describe global securities in greater detail below. We refer to those persons who have securities registered in their own names on the books that we or any applicable trustee or depositary maintain for this purpose as the “holders” of those securities. These persons are the legal holders of the securities. We refer to those persons who, indirectly through others, own beneficial interests in securities that are not registered in their own names, as “indirect holders” of those securities. As we discuss below, indirect holders are not legal holders, and investors in securities issued in book-entry form or in street name will be indirect holders.

Book-Entry Holders

We may issue securities in book-entry form only, as we will specify in the applicable prospectus supplement. This means securities may be represented by one or more global securities registered in the name of a financial institution that holds them as depositary on behalf of other financial institutions that participate in the depositary’s book-entry system. These participating institutions, which are referred to as participants, in turn, hold beneficial interests in the securities on behalf of themselves or their customers.

Only the person in whose name a security is registered is recognized as the holder of that security. Global securities will be registered in the name of the depositary or its participants. Consequently, for global securities, we will recognize only the depositary as the holder of the securities, and we will make all payments on the securities to the depositary. The depositary passes along the payments it receives to its participants, which in turn pass the payments along to their customers who are the beneficial owners. The depositary and its participants do so under agreements they have made with one another or with their customers; they are not obligated to do so under the terms of the securities.

As a result, investors in a global security will not own securities directly. Instead, they will own beneficial interests in a global security, through a bank, broker or other financial institution that participates in the depositary’s book-entry system or holds an interest through a participant. As long as the securities are issued in global form, investors will be indirect holders, and not legal holders, of the securities.

Street Name Holders

We may terminate a global security or issue securities that are not issued in global form. In these cases, investors may choose to hold their securities in their own names or in “street name.” Securities held by an investor in street name would be registered in the name of a bank, broker or other financial institution that the investor chooses, and the investor would hold only a beneficial interest in those securities through an account he or she maintains at that institution.

For securities held in street name, we or any applicable trustee or depositary will recognize only the intermediary banks, brokers and other financial institutions in whose names the securities are registered as the holders of those securities, and we or any such trustee or depositary will make all payments on those securities to them. These institutions pass along the payments they receive to their customers who are the beneficial owners, but only because they agree to do so in their customer agreements or because they are legally required to do so. Investors who hold securities in street name will be indirect holders, not holders, of those securities.

Legal Holders

Our obligations, as well as the obligations of any applicable trustee or third party employed by us or a trustee, run only to the legal holders of the securities. We do not have obligations to investors who hold beneficial interests in global securities, in street name or by any other indirect means. This will be the case whether an investor chooses to be an indirect holder of a security or has no choice because we are issuing the securities only in global form.

For example, once we make a payment or give a notice to the legal holder, we have no further responsibility for the payment or notice even if that legal holder is required, under agreements with its participants or customers or by law, to pass it along to the indirect holders but does not do so. Similarly, we may want to obtain the approval of the holders to amend an indenture, to relieve us of the consequences of a default or of our obligation to comply with a particular provision of an indenture, or for other purposes. In such an event, we would seek approval only from the legal holder, and not the indirect holders, of the securities. Whether and how the legal holders contact the indirect holders is up to the legal holders.

Special Considerations for Indirect Holders

If you hold securities through a bank, broker or other financial institution, either in book-entry form because the securities are represented by one or more global securities or in street name, you should check with your own institution to find out:

Global Securities

A global security is a security that represents one or any other number of individual securities held by a depositary. Generally, all securities represented by the same global securities will have the same terms.

Each security issued in book-entry form will be represented by a global security that we issue to, deposit with and register in the name of a financial institution or its nominee that we select. The financial institution that we select for this purpose is called the depositary. Unless we specify otherwise in the applicable prospectus supplement, DTC, New York, New York, will be the depositary for all securities issued in book-entry form.

A global security may not be transferred to or registered in the name of anyone other than the depositary, its nominee or a successor depositary, unless special termination situations arise. We describe those situations below under “—Special Situations When a Global Security Will Be Terminated.” As a result of these arrangements, the depositary, or its nominee, will be the sole registered owner and legal holder of all securities represented by a global security, and investors will be permitted to own only beneficial interests in a global security. Beneficial interests must be held by means of an account with a broker, bank or other financial institution that in turn has an account with the depositary or with another institution that does. Thus, an investor whose security is represented by a global security will not be a legal holder of the security, but only an indirect holder of a beneficial interest in the global security.

If the prospectus supplement for a particular security indicates that the security will be issued as a global security, then the security will be represented by a global security at all times unless and until the global security is terminated. If termination occurs, we may issue the securities through another book-entry clearing system or decide that the securities may no longer be held through any book-entry clearing system.

Special Considerations for Global Securities

As an indirect holder, an investor’s rights relating to a global security will be governed by the account rules of the investor’s financial institution and of the depositary, as well as general laws relating to securities transfers. We do not recognize an indirect holder as a holder of securities and instead deal only with the depositary that holds the global security.

If securities are issued only as global securities, an investor should be aware of the following:

There may be more than one financial intermediary in the chain of ownership for an investor. We do not monitor and are not responsible for the actions of any of those intermediaries.

Special Situations When a Global Security Will Be Terminated

In a few special situations described below, a global security will terminate and interests in it will be exchanged for physical certificates representing those interests. After that exchange, the choice of whether to hold securities directly or in street name will be up to the investor. Investors must consult their own banks or brokers to find out how to have their interests in securities transferred to their own names, so that they will be direct holders. We have described the rights of holders and street name investors above.

Unless we provide otherwise in the applicable prospectus supplement, the global security will terminate when the following special situations occur:

The applicable prospectus supplement may also list additional situations for terminating a global security that would apply only to the particular series of securities covered by the prospectus supplement. When a global security terminates, the depositary, and neither we nor any applicable trustee, is responsible for deciding the names of the institutions that will be the initial direct holders.

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. We may sell the securities to or through underwriters or dealers, through agents or directly to one or more purchasers. We may distribute securities from time to time in one or more transactions:

We may also sell equity securities covered by this registration statement in an “at the market” offering as defined in Rule 144415 under the Securities Act.

Such offering may be made into an existing trading market for such securities in transactions at other than a fixed price, either:

Such “at the market” offerings, if any, may be conducted by underwriters acting as principal or agent.

A prospectus supplement or supplements (and any related free writing prospectus that we may authorize to be provided to you) will describe the terms of the offering of the securities, including, to the extent applicable:

Only underwriters named in the prospectus supplement are underwriters of the securities offered by the prospectus supplement.

If underwriters are used in the sale, they will acquire the securities for their own account and may resell the securities from time to time in one or more transactions at a fixed public offering price or at varying prices determined at the time of sale. The obligations of the underwriters to purchase the securities will be subject to the conditions set forth in the applicable underwriting agreement. We may offer the securities to the public through underwriting syndicates represented by managing underwriters or by underwriters without a syndicate. Subject to certain conditions, the underwriters will be obligated to purchase all of the securities offered by the prospectus supplement. Any public offering price and any discounts or concessions allowed or reallowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. We will describe in the prospectus supplement, naming the underwriter, the nature of any such relationship.

We may sell securities directly or through agents we designate from time to time. We will name any agent involved in the offering and sale of securities, and we will describe any commissions we will pay the agent in the prospectus supplement. Unless the prospectus supplement states otherwise, our agent will act on a best-efforts basis for the period of its appointment.

We may authorize agents or underwriters to solicit offers by certain types of institutional investors to purchase securities from us at the public offering price set forth in the prospectus supplement pursuant to delayed delivery contracts providing for payment and delivery on a specified date in the future. We will describe the conditions to these contracts and the commissions we must pay for solicitation of these contracts in the prospectus supplement.

We may provide agents and underwriters with indemnification against civil liabilities related to this offering, including liabilities under the Securities Act, or contribution with respect to payments that the agents or underwriters may make with respect to these liabilities. Agents and underwriters may engage in transactions with, or perform services for, us in the ordinary course of business.

All securities we offer, other than common stock, will be new issues of securities with no established trading market. Any underwriters may make a market in these securities, but will not be obligated to do so and may discontinue any market making at any time without notice. We cannot guarantee the liquidity of the trading markets for any securities.

Any underwriter may engage in overallotment, stabilizing transactions, short covering transactions and penalty bids. Overallotment involves sales in excess of the offering size, which create a short position. Stabilizing transactions permit bids to purchase the underlying security so long as the stabilizing bids do not exceed a specified maximum. Short covering transactions involve purchases of the securities in the open market after the distribution is completed to cover short positions. Penalty bids permit the underwriters to reclaim a selling concession from a dealer when the securities originally sold by the selling stockholder withoutdealer are purchased in a stabilizing or covering transaction to cover short positions. Those activities may cause the price of the securities to be higher than it would otherwise be. If commenced, the underwriters may discontinue any of the activities at any time. These transactions may be effected on any exchange or over-the-counter market or otherwise.

Any underwriters who are qualified market makers on Nasdaq may engage in passive market making transactions in the securities on Nasdaq in accordance with Rule 103 of Regulation M, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the securities. Passive market makers must comply with applicable volume and price limitations and must be identified as passive market makers. In general, a passive market maker must display its bid at a price not in excess of the highest independent bid for such security; if all independent bids are lowered below the passive market maker’s bid, however, the passive market maker’s bid must then be lowered when certain purchase limits are exceeded. Passive market making may stabilize the market price of the securities at a level above that which might otherwise prevail in the open market and, if commenced, may be discontinued at any time.

VALIDITY OF SECURITIES

Unless otherwise indicated in the applicable prospectus supplement, certain legal matters in connection with the offering and the validity of the securities offered by this prospectus, and any supplement thereto, will be passed upon by Sullivan & Cromwell LLP, New York, New York. Additional legal matters may be passed upon for us or manner-of-sale restrictions,any underwriters, dealers or agents, by counsel that we will name in the applicable prospectus supplement.

EXPERTS

The consolidated financial statements of Protara Therapeutics, Inc. appearing in Protara Therapeutic, Inc.’s Annual Report (Form 10-K) for the year ended December 31, 2022, have been audited by Ernst & Young LLP, independent registered public accounting firm, as set forth in their report thereon included therein, and without complianceincorporated herein by reference. Such financial statements are, and audited financial statements to be included in subsequently filed documents will be, incorporated herein in reliance upon the report of Ernst & Young LLP pertaining to such financial statements (to the extent covered by consents filed with any “current public information” requirement, pursuant to Rule 144the Securities and Exchange Commission) given on the authority of such firm as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus is part of the registration statement on Form S-3 we filed with the SEC under the Securities Act. We filed thisThis prospectus does not contain all of the information set forth in the registration statement and the exhibits to the registration statement. For further information with respect to us and the securities we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement. You should rely only on the information contained in this prospectus or incorporated by reference. We have not authorized anyone else to provide you with different information. We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the time of delivery of this prospectus or any sale of the securities offered by this prospectus.

We must comply with ourthe informational requirements under the Registration Rights Agreement.

If, at any time prior to the date that no investors hold Registrable Securities, the Company (i) files with the SEC a registration statement under the Securities Act relating to an offering for its own account or for the account of any other holder of its equity securities (other than securities being registered on Form S-4 or Form S-8), and/or (ii) otherwise effects an underwritten offering of any securities of the Company of a type included in a then effective registration statement, then, subject to certain limitations,Exchange Act, and we are required to send each Investor written notice of such action and include in such registration statement and/or underwritten offering all or any part of such investor’s Registrable Securities that the investor requests, or the underwriters allow, to be included in such registration statement and/or the underwritten offering.

If the Company fails to comply with specified provisions in the Registration Rights Agreement, including if a registration statement is not filed with the SEC as required by the Registration Rights Agreement, then we will agree to pay each investor, in addition to all other available remedies, damages, for each 30-day period after the date of such failure until it is cured, an amount in cash equal to one and one-half percent (1.5%) of the product of (i) the sum of (x) the aggregate number of Conversion Shares that are then issued and issuable upon conversion of the Preferred Shares that constitute Registrable Securities and are included, or to be included, as applicable, in the registration statement, as of the date such registration failure occurs (without regard to any limitations on conversion or issuance set forth in the Certificate of Designation), plus (y) all other shares of common stock that constitute Registrable Securities and are included, or to be included, as applicable, in such Registration Statement, as of the date such registration failure occurs, multiplied by (ii) the volume weighted average price of the common stock on such date.

 Implications of Being an Emerging Growth Company

We are an “emerging growth company,” as defined in the Jumpstart Our Business Startups Act of 2012. We will remain an emerging growth company until the earlier of (i) the beginning of the first fiscal year following the fifth anniversary of our initial public offering, (ii) the beginning of the first fiscal year after our annual gross revenue is $1.07 billion or more, (iii) the date on which we have, during the previous three-year period, issued more than $1.0 billion in non-convertible debt securities and (iv) as of the end of any fiscal year in which the market value of our common stock held by non-affiliates exceeded $700 million as of the end of the second quarter of that fiscal year.

For as long as we remain an “emerging growth company,” we may take advantage of certain exemptions from various reporting requirements that are applicable to public companies that are not “emerging growth companies” including, but not limited to, not being required to comply with the auditor attestation requirements of Section 404 of the Sarbanes-Oxley Act, reduced disclosure obligations regarding executive compensation and financial statements in our periodicfile reports and proxy statements and exemptions fromother information with the requirements of holdingSEC. You may read and copy these reports, proxy statements and other information on the SEC’s website at http://www.sec.gov, which contains reports, proxy and information statements and other information regarding issuers like us that file electronically with the SEC. We maintain a nonbinding advisory vote to approve executive compensation and shareholder approval of any golden parachute payments not previously approved. We plan to take advantage of these reporting exemptions until we are no longer an “emerging growth company.”

Corporate Information

We were incorporated in Delaware in March 2006, andwebsite at that time, acquired Proteon Therapeutics, LLC, our predecessor, which was formed in June 2001. Our principal executive offices are located at 200 West Street, Waltham, Massachusetts 02451, and our telephone number is (781) 890-0102. Our website address is www.proteontherapeutics.com.www.protaratx.com. The information contained in, or that can be accessed through, our website is not part of this prospectus.

THE OFFERING

Unless otherwise stated, all information in this prospectus assumes no conversion of the Series A Preferred Stock, no exercise of outstanding options or warrants to purchase common stock and no issuance of shares available for future issuance under our equity compensation plans.

RISK FACTORS

An investment in our securities involves a high degree of risk. Before making an investment decision, you should carefully consider the risks described below and under “Risk Factors” in the applicable prospectus supplement and in our most recent Annual Report on Form 10-K, and in our updates to those Risk Factors in our Quarterly Reports on Form 10-Q or Current Reports on Form 8-K following the most recent Form 10-K, and in all other information appearing in this prospectus or incorporated by reference into this prospectus and any applicable prospectus supplement. The material risks and uncertainties that management believes affect us will be described in those documents. In addition to those risk factors, there may be additional risks and uncertainties of which management is not aware or focused on or that management deems immaterial. Our business, financial condition or results of operations could be materially adversely affected by any of these risks. The trading price of our securities could decline due to any of these risks, and you may lose all or part of your investment. This prospectus is qualified in its entirety by these risk factors.

Additional Risks Relating to This Offering and Our Common Stock

The sale of a substantial amount of our common stock, including resale of the shares of common stock issuable upon the conversion of the Series A Preferred Stock acquired in the Transaction, in the public market after this offering could adversely affect the prevailing market price of our common stock and cause stockholders to experience dilution.

We have outstanding an aggregate of 17,619,418 shares of our common stock as of August 2, 2017. We have received stockholder approval for the Transaction and, therefore, the outstanding shares of Series A Preferred Stock are convertible into our common stock at each Investor’s election, subject to the Blocker. The Series A Preferred Stock is convertible into an aggregate of 22,112,775 shares of common stock, subject to adjustment as provided in the Certificate of Designation. Pursuant to the registration rights granted in the Transaction, we agreed to register the resale by the selling stockholders named herein of these shares of common stock. Upon such registration, these shares will become generally available for immediate resale, subject to the Blocker. Sales of substantial amounts of shares of our common stock in the public market, or the perception that such sales might occur, could adversely affect the market price of our common stock, and the market value of our other securities, and could result in substantial dilution to shareholders who held our common stock prior to the Transaction. In addition, we may issue additional shares of common stock or other equity or debt securities convertible into common stock in connection with a future financing, acquisition, litigation settlement, employee arrangements or otherwise. Any such issuance could result in substantial dilution to our existing stockholders and could cause our stock price to decline.

A substantial number of shares of common stock are being offered by this prospectus, and we cannot predict if and when the purchasers may sell such shares in the public markets. In addition, certain holders of our common shares have additional rights, subject to some conditions, to require us to file registration statements covering the sale of their shares or to include their shares in registration statements that we may file for ourselves or other stockholders. We have also registered the offer and sale of all shares of common stock that we may issue under our equity compensation plans. Furthermore, in the future, we may issue additional shares of common stock or other equity or debt securities convertible into common stock in connection with a financing, acquisition, litigation settlement, employee arrangements or otherwise. Any such issuance could result in substantial dilution to our existing stockholders and could cause our stock price to decline.

Our share price may be volatile, which could subject us to securities class action litigation and our stockholders could incur substantial losses.

The market price of shares of our common stock could be subject to wide fluctuations in response to many risk factors listed in this section, and others beyond our control, including:

These and other market and industry factors may cause the market price and demand for our common stock to fluctuate substantially, regardless of our actual operating performance, which may limit or prevent investors from readily selling their shares of common stock and may otherwise negatively affect the liquidity of our common stock. In addition, the stock market in general, and NASDAQ and emerging growth companies in particular, have experienced extreme price and volume fluctuations that have often been unrelated or disproportionate to the operating performance of these companies. In the past, when the market price of a stock has been volatile, holders of that stock have instituted securities class action litigation against the company that issued the stock. If in the future any of our stockholders brought a lawsuit against us, we could incur significant legal expenses, settlement costs or damage awards that are not covered by, or exceed the limits of, our available directors’ and officers’ liability insurance, which could adversely impact our financial condition, results of operations or cash flows. Such a lawsuit could also divert the time and attention of our management.

CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus and each prospectus supplement, including the documents that we incorporate by reference, contains or may contain forward-looking statements as that term is defined in the federal securities laws. The events described in forward-looking statements contained in this prospectus, including the documents that we incorporate by reference, may not occur. Generally, these statements relate to our business plans or strategies, projected or anticipated benefits or other consequences of our plans or strategies, financing plans, projected or anticipated benefits from acquisitions that we may make, or projections involving anticipated revenues, earnings or other aspects of our operating results or financial position, and the outcome of any contingencies. Any such forward-looking statements are based on current expectations, estimates and projections of management. We intend for these forward-looking statements to be covered by the safe-harbor provisions for forward-looking statements. Words such as “may,” “expect,” “believe,” “anticipate,” “project,” “plan,” “intend,” “estimate,” and “continue,” and their opposites and similar expressions are intended to identify forward-looking statements. We caution you that these statements are not guarantees of future performance or events and are subject to a number of uncertainties, risks and other influences.

These forward-looking statements are subject to a number of risks, uncertainties and assumptions, including, but not limited to:

You should also consider carefully the statements set forth in the section titled “Risk Factors” or elsewhere in this prospectus and the documents incorporated or deemed incorporated herein by reference, including but not limited to the risks described in under “Risk Factors” and elsewhere in our most recent Annual Report on Form 10-K and in our updates to those risk factors in our Quarterly Reports on Form 10-Q and Current Reports on Form 8-K and other factors described elsewhere in this prospectus. Any one or more of these uncertainties, risks and other influences could materially affect our results of operations and whether forward-looking statements made by us ultimately prove to be accurate. Our actual results, performance and achievements could differ materially from those expressed or implied in these forward-looking statements. Except as otherwise required by law, we undertake no obligation to publicly update or revise any forward-looking statements, whether from new information, future events or otherwise.

USE OF PROCEEDS

We will not receive any proceeds from the sale of our common stock by the selling stockholders.

The selling stockholders will pay any underwriting discounts and commissions and any similar expenses it incurs in disposing of the common stock. We will bear all other reasonable costs, fees and expenses incurred in effecting the registration of the common stock covered by this prospectus, including all registration and filing fees, fees and expenses of compliance with securities or “blue sky” laws, listing application fees, printing expenses, transfer agent’s and registrar’s fees, costs of distributing prospectuses in preliminary and final form as well as any supplements thereto, and fees and disbursements of counsel for the Company and all independent certified public accountants and other persons retained by the Company.

SELLING STOCKHOLDERS

As described in the prospectus summary, in the Transaction, the selling stockholders acquired shares of our Series A Preferred Stock that are convertible into shares of our common stock, subject to the limitations described below. In connection with the closing of the Transaction, we entered into the Registration Rights Agreement, pursuant to which we agreed to prepare and file one or more registration statements covering the resale of the shares of common stock issuable upon the conversion of the Series A Preferred Stock acquired in the Transaction (without regard to the limitation described below), and to maintain the effectiveness of such registration statement(s) until all the shares of common stock have been sold in accordance with the Registration Statement or in accordance with Rule 144 under the Securities Act or may be sold by the selling stockholder without volume or manner-of-sale restrictions, and without compliance with any “current public information” requirement, pursuant to Rule 144 under the Securities Act. We are filing this registration statement to comply with our requirements under the Registration Rights Agreement.

Under the terms of the Series A Preferred Stock, any conversion of Series A Preferred Stock by a holder into shares of common stock will be prohibited to the extent that, as a result of such conversion, the holder, together with its affiliates and any other person or entity whose beneficial ownership of common stock would be aggregated with such holder’s for purposes of Section 13(d) of the Securities and Exchange Act of 1934, as amended, would beneficially own more than 9.985% of the total number of shares of common stock issued and outstanding after giving effect to such conversion (the “Blocker”). The Blocker may not be waived and shall apply to any successor holder of shares of Series A Preferred Stock. The table below does not reflect such limitation, with the effect that beneficial ownership of the selling stockholders is calculated and presented (for purposes of disclosure in this prospectus only) on a fully as converted basis. This table is based upon information supplied by the selling stockholders.

The following table sets forth information as of August 2, 2017, and includes the shares of our common stock beneficially owned by each of the selling stockholders (as well as certain shares of Common Stock that, as a result of the Blocker, the selling stockholders may not currently have the right to acquire), the shares of common stock being registered for sale and offered for sale by each of the selling stockholders, and the shares of common stock that will be beneficially owned by each of the selling stockholders upon sale of the shares registered for resale, assuming that such selling stockholder sells all shares of common stock potentially issuable upon conversion of the Series A Preferred Stock acquired by such selling stockholder in the Transaction. The percentage of shares owned in the table below is based on 39,732,193 shares of common stock outstanding, which includes 17,619,418 shares of common stock outstanding as of August 2, 2017 and assumes the sale of 22,112,775 shares of common stock potentially issuable upon conversion of the Series A Preferred Stock as of the date of this prospectus. Only those selling stockholders listed below or their transferees, pledgees, donees, assignees, distributees or successors in interest may offer and sell the common stock pursuant to this prospectus and any accompanying prospectus supplement. The selling stockholders may offer all or less than all of the shares listed in the table below for sale pursuant to this prospectus and any accompanying prospectus supplement from time to time. Accordingly, no estimate can be given as to the shares of common stock that the selling stockholders will hold upon consummation of any such sales. Beneficial ownership is determined in accordance with the rules of the SEC, except that the following table does not reflect the limitations of the Blocker described above, with the effect that beneficial ownership of the selling stockholders is calculated and presented (for purposes of disclosure in this prospectus only) on a fully as converted basis.

_________________

No offer or sale pursuant to this prospectus may occur unless the registration statement that includes this prospectus has been declared effective by the SEC and remains effective at the time a selling stockholder offers or sells shares of Common Stock. We are required, under certain circumstances, to update, supplement or amend this prospectus to reflect material developments in our business, financial position and results of operations and may do so by an amendment to this prospectus, a prospectus supplement or a future filing with the SEC incorporated by reference in this prospectus.

PLAN OF DISTRIBUTION

 Each selling stockholder of the securities named herein and any of their transferees, pledgees, donees, assignees, distributees or successors in interest (all of which may be selling stockholders) may, from time to time, sell any or all of their securities covered hereby on any stock exchange, market or trading facility on which the securities are traded, in private transactions or otherwise. These sales may be at fixed or negotiated prices or at market prices prevailing at the time of sale. A selling stockholder may use any one or more of the following methods when selling securities:

The selling stockholders may also sell securities under Rule 144 or any other exemption from registration under the Securities Act, if available, rather than under this prospectus.

Broker-dealers engaged by the selling stockholders may arrange for other brokers-dealers to participate in sales. Broker-dealers may receive commissions or discounts from the selling stockholders (or, if any broker-dealer acts as agent for the purchaser of securities, from the purchaser) in amounts to be negotiated, but, except as set forth in a supplement to this Prospectus, in the case of an agency transaction not in excess of a customary brokerage commission in compliance with FINRA Rule 2440; and in the case of a principal transaction a markup or markdown in compliance with FINRA IM-2440.

In connection with the sale of the securities or interests therein, the selling stockholders may enter into hedging transactions with broker-dealers or other financial institutions, which may in turn engage in short sales of the securities in the course of hedging the positions they assume. The selling stockholders may also sell securities short and deliver these securities to close out their short positions, or loan or pledge the securities to broker-dealers that in turn may sell these securities. The selling stockholders may also enter into option or other transactions with broker-dealers or other financial institutions or create one or more derivative securities which require the delivery to such broker-dealer or other financial institution of securities offered by this prospectus, which securities such broker-dealer or other financial institution may resell pursuant to this prospectus (as supplemented or amended to reflect such transaction).

The selling stockholders may pledge or grant a security interest in some of all of the shares of common stock owned by them and, if any of them defaults in the performance of its secured obligations, the pledgees or secured parties may offer and sell the shares of common stock from time to time pursuant to this prospectus or any supplement or amendment to this prospectus under Rule 424(b)(3) or other applicable provision of the Securities Act, amending, if necessary, the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under this prospectus. The selling stockholders also may transfer and donate the shares of common stock in other circumstances in which case the transferees, donees or other successors in interest will be the selling beneficial owners for purposes of this prospectus.

The selling stockholders and any broker-dealers or agents that are involved in selling the securities may be deemed to be “underwriters” within the meaning of the Securities Act in connection with such sales. In such event, any commissions received by such broker-dealers or agents and any profit on the resale of the securities purchased by them may be deemed to be underwriting commissions or discounts under the Securities Act. We are not aware that any selling stockholder has any written or oral agreement or understanding, directly or indirectly, with any person to distribute the securities.

We are required to pay certain fees and expenses incurred by us incident to the registration of the securities. We have agreed to indemnify the selling stockholders against certain losses, claims, damages and liabilities, including liabilities under the Securities Act.

We agreed to keep this prospectus effective until the earlier of (i) the date on which the securities may be resold by the selling stockholders without registration or restriction (including any volume or manner-of-sale limitations pursuant to Rule 144), without the requirement for us to be in compliance with the current public information requirement under Rule 144 under the Securities Act or any other rule of similar effect or (ii) all of the securities have been sold pursuant to this prospectus or Rule 144 under the Securities Act or any other rule of similar effect. The resale securities will be sold only through registered or licensed brokers or dealers if required under applicable state securities laws.

Under applicable rules and regulations under the Exchange Act, any person engaged in the distribution of the shares of common stock may not simultaneously engage in market making activities with respect to the common stock for the applicable restricted period, as defined in Regulation M, prior to the commencement of the distribution. In addition, the selling stockholders will be subject to applicable provisions of the Exchange Act and the rules and regulations thereunder, including Regulation M, which may limit the timing of purchases and sales of the common stock by the selling stockholders or any other person. We will make copies of this prospectus available to the selling stockholders.

LEGAL MATTERS

The validity of the securities being offered hereby will be passed upon by Morgan, Lewis & Bockius LLP.

EXPERTS

Ernst & Young LLP, independent registered public accounting firm, has audited our consolidated financial statements included in our Annual Report on Form 10-K for the year ended December 31, 2016, as set forth in their report, which is incorporated by reference in this prospectus and elsewhere in the registration statement. Our financial statements are incorporated by reference in reliance on Ernst & Young LLP’s report, given on their authority as experts in accounting and auditing.

DISCLOSURE OF COMMISSION POSITION

ON INDEMNIFICATION FOR SECURITIES ACT LIABILITIES

Section 145 of the Delaware General Corporation Law, or DGCL, or Section 145, provides that we may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal or investigative (other than an action by us or in our right) by reason of the fact that he is or was our director, officer, employee or agent, or is or was serving at our request as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys’ fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by him or her in connection with such action, suit or proceeding if he acted in good faith and in a manner he or she reasonably believed to be in or not opposed to our best interests, and, with respect to any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful. Section 145 further provides that we similarly may indemnify any such person serving in any such capacity who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by is or in our right to procure judgment in our favor, against expenses actually and reasonably incurred in connection with the defense or settlement of such action or suit if he or she acted in good faith and in a manner he reasonably believed to be in or not opposed to our best interests and except that no indemnification shall be made in respect of any claim, issue or matter as to which such person shall have been adjudged to be liable to us unless and only to the extent that the Delaware Court of Chancery or such other court in which such action or suit was brought shall determine upon application that, despite the adjudication of liability but in view of all the circumstances of the case, such person is fairly and reasonably entitled to indemnity for such expenses which the Delaware Court of Chancery or such other court shall deem proper.

Our amended and restated certificate of incorporation and bylaws provide that, to the fullest extent permitted by the DGCL, our directors shall not be liable to us or our stockholders for monetary damages for any breach of fiduciary duty as a director, and that we shall, to the maximum extent permitted under the DGCL, indemnify any person who was or is made a party or is threatened to be made a party to any threatened, pending or completed action, suit, proceeding or claim, whether civil, criminal, administrative or investigative, by reason of the fact that such person is or was or has agreed to be our director or officer or while a director or officer is or was serving at our request as a director, officer, partner, trustee, employee, or agent of any corporation, partnership, joint venture, trust or other enterprise, including service with respect to employee benefit plans, against expenses (including attorney’s fees), judgments, fines, penalties and amounts paid in settlement incurred in connection with the investigation, preparation to defend or defense of such action, suit, proceeding or claim.

Insofar as indemnification for liabilities arising under the Securities Act may be permitted to our directors, officers and controlling persons pursuant to the foregoing provisions, or otherwise, we have been advised that in the opinion of the SEC such indemnification is against public policy as expressed in the Securities Act and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, we will, unless in the opinion of our counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by us is against public policy as expressed in the Securities Act and will be governed by the final adjudication of such issue.

ADDITIONAL INFORMATION

This prospectus is part of a Registration Statement on Form S-3 that we have filed with the SEC relating to the shares of our securities being offered hereby. This prospectus does not contain all of the information in the Registration Statement and its exhibits. The Registration Statement, its exhibits and the documents incorporated by reference in this prospectus and their exhibits, all contain information that is material to the offering of the Securities hereby. Whenever a reference is made in this prospectus to any of our contracts or other documents, the reference may not be complete. You should refer to the exhibits that are a part of the Registration Statement in order to review a copy of the contract or documents. The Registration Statement and the exhibits are available at the SEC’s Public Reference Room or through its Website.

We file annual, quarterly and current reports, proxy statements and other information with the SEC. You can read and copy any materials we file with the SEC at its Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549 and at its regional offices, a list of which is available on the Internet at http://www.sec.gov/contact/addresses.htm. You may obtain information on the operation of the Public Reference Room by calling the SEC at 1-800-SEC-0330. The SEC maintains an Internet site at http://www.sec.gov that contains reports, proxy and information statements, and other information regarding issuers, such as us, that file electronically with the SEC. Additionally, you may access our filings with the SEC through our website at http://www.proteontherapeutics.com. The information on our website is not part of this prospectus.

We will provide you without charge, upon your oral or written request, with a copy of any or all reports, proxy statements and other documents we file with the SEC, as well as any or all of the documents incorporated by referenceStatements contained in this prospectus as to the contents of any contract or other document are not necessarily complete, and in each instance we refer you to the copy of the contract or document filed as an exhibit to the registration statement, (other than exhibits toeach such documents unlessstatement being qualified in all respects by such exhibits are specifically incorporated by reference into such documents). Requests for such copies should be directed to:reference.

You should rely only on the information in this prospectus and the additional information described above and under the heading “Incorporation of Certain Information by Reference” below. We have not, and the selling stockholders have not, authorized any other person to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely upon it. The selling stockholders are not making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information in this prospectus was accurate on the date of the front cover of this prospectus only, and that any information we have incorporated by reference was accurate on the date of the document incorporated by reference only. Our business, financial condition, results of operations and prospects may have changed since such date.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” information that we file with it, into this prospectus, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is an important part of this prospectus. TheInformation in this prospectus supersedes information incorporated by reference is consideredthat we filed with the SEC prior to be a partthe date of this prospectus, andwhile information that we file later with the SEC will automatically update and supersede information contained in documents filed earlier with the SEC or containedinformation in this prospectus and any accompanying prospectus supplement.

prospectus. We also incorporate by reference into this prospectus the documents listed below that we have previously filed with the SEC:

All reports and other documents that we fileany future filings made by us with the SEC (other than current reports or portions thereof furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items and other portions of documents that are furnished, but not filed, pursuant to applicable rules promulgated by the SEC) that are filed by us with the SEC pursuant to Sections 13(a), 13(c), 14 or 15(d) of the Exchange Act (i) after the date of the initial filing of the registration statement of which this prospectus is a part and prior to effectiveness of the registration statement, and (ii) after the effectiveness of the registration statement but beforeprior to the termination of the offering of the Securities hereundersecurities covered by the applicable prospectus supplement:

We will also be considered to be incorporated by reference into this prospectus from the date of the filing of these reports and documents, and will supersede the information herein; provided, however, that all reports or portions thereof that we “furnish” to the SEC will not be considered incorporated by reference into this prospectus. We undertake to providefurnish without charge to each person, (includingincluding any beneficial owner) who receives a copy ofowner, to whom this prospectus supplement and the accompanying prospectus is delivered, upon written or oral request, a copy of allany document incorporated by reference. Requests should be addressed to 345 Park Avenue South, Third Floor, New York, New York 10010, Attn: Secretary or may be made telephonically at (646) 844-0337. Copies of these filings are filings are also available, without charge, on the SEC’s website at www.sec.gov and on our website www.protaratx.com as soon as reasonably practicable after they are filed electronically with the SEC. The information contained on our website is not part of this prospectus supplement or the accompanying prospectus.

In accordance with Rule 412 of the preceding documents that areSecurities Act, any statement contained in a document incorporated by reference (other than exhibits, unlessin this prospectus supplement or the exhibits are specificallyaccompanying prospectus shall be deemed modified, superseded or replaced for the purposes of this prospectus supplement or the accompanying prospectus to the extent that a statement contained in this prospectus supplement or the accompanying prospectus or in any other subsequently filed document that also is or is deemed to be incorporated by reference into these documents). You may request a copy of these materials in the manner set forth under the heading “Additional Information,” above.

herein modifies or supersedes such statement.

22,112,775 Shares

of

Common Stock

PROSPECTUS

___________________, 2017

PART II

INFORMATION NOT REQUIRED IN THE PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution.Distribution

SetThe following table sets forth below is an estimate (except in the case of the registration fee) of the amount of feesestimated costs and expenses, to be incurred in connection with the issuance and distribution of the offered securities registered hereby, other than underwriting discounts and commission, if any, incurredcommissions, payable by us in connection with the saleoffering of the offered securities.securities being registered. All suchthe amounts will be borne by Proteon Therapeutics,shown are estimates, except for the SEC registration fee and the Financial Industry Regulatory Authority, Inc., or FINRA, filing fee.

Item 15. Indemnification of DirectorsOfficers and Officers.

Under Section 145 of the Delaware Law, the registrant has broad powers to indemnify its directors and officers against liabilities they may incur in such capacities, including liabilities under the Securities Act.Directors

The registrant’s certificate of incorporation and bylaws include provisions which (i) eliminateprovide for indemnification of the personal liability of itsregistrant’s directors for monetary damages resulting from breaches of their fiduciary duty to the extent permitted by Delaware Law and (ii) require the registrant to indemnify its directors, officers employees and agents to the fullest extent permitted by law. Insofar as indemnification for liabilities under the Securities Act of 1933, as amended, or the Securities Act, may be permitted to directors, officers or controlling persons of the registrant pursuant to the registrant’s certificate of incorporation, bylaws and the Delaware General Corporation Law, including circumstancesor DGCL, the registrant has been informed that in whichthe opinion of the SEC such indemnification is otherwise discretionary. Pursuant to against public policy as expressed in the Securities Act and is therefore unenforceable.

Section 145102(b)(7) of the Delaware Law,DGCL provides that a corporation generally hascertificate of incorporation may include a provision that eliminates or limits the power to indemnify its present and former directors, officers, employees and agents against expenses incurred by them in connection with any suit to which they are, or are threatened to be made,personal liability of a party by reason of their serving in such positions so long as they acted in good faith and in a manner they reasonably believed to be in or not opposeddirector to the best interestscorporation or its stockholders for monetary damages for breach of the corporation and, with respect tofiduciary duty as a director, except for liability (i) for any criminal action, had no reasonable cause to believe their conduct was unlawful. The registrant believes that these provisions are necessary to attract and retain qualified persons as directors and executive officers. These provisions do not eliminate the directors’ duty of care, and, in appropriate circumstances, equitable remedies such as injunctive or other forms of non-monetary relief will remain available under Delaware Law. In addition, each director will continue to be subject to liability for breach of the director’s duty of loyalty to the registrant,Company or its stockholders, (ii) for acts or omissions not in good faith or involvingthat involve intentional misconduct foror a knowing violationsviolation of law, for acts(iii) under Section 174 of the DGCL, relating to prohibited dividends or omissions that the director believes to be contrary to the registrant’s best interestsdistributions or the best interestsrepurchase or redemption of the registrant’s stockholders,stock or (iv) for any transaction from which the director derivedderives an improper personal benefit,benefit. The registrant’s certificate of incorporation includes such a provision. As a result of this provision, the registrant and any act relatedits stockholders may be unable to unlawful stock repurchases, redemptionsobtain monetary damages from a director for breach of his or other distribution or paymentsher duty of dividends. The provision also does not affect a director’s responsibilities under any other law, such as the federal securities law or state or federal environmental laws.care.

The

As permitted under the DGCL, the registrant has entered into indemnityindemnification agreements with certaineach of its directors and executive officers that require the registrant to indemnify such persons against any and all expenses (including attorneys’, witness or other professional fees), and unless in connection with a proceeding by or in the right of the registrant, any and all judgments, fines settlements and other amounts paid in settlement, actually and reasonably incurred (including expenses of a derivative action)by such persons or on such persons’ behalf in connection with any proceeding, whether actual or threatened, to which any such person may be madeinvolved as a party or otherwise by reason of the fact that such person is or was onea director or an executive officer of the registrant’s directorsregistrant or executive officers,is or was serving at the request of the registrant as a director, officer, employee, agent or fiduciary of another enterprise, provided among other things, thatsuch person acted in good faith and in a manner such person reasonably believed to be in or not opposed to the best interests of the registrant and, with respect to any criminal proceeding, had no reasonable cause to believe such person’s conduct was unlawful. Under these agreements, the registrant is not knowingly fraudulent or deliberately dishonest or constituted willful misconduct. required to provide indemnification for certain matters, including:

The indemnification agreements also set forth certain procedures, presumptions and remedies that will apply in the event of a claim for indemnification thereunder.

At present, there is no pending litigation or proceeding involving any of the registrant’s directors or executive officers as to which indemnification is being sought nor is the registrant aware of any threatened litigationAny underwriting agreement that we may result in claimsenter into may provide for indemnification by any executive officer or director.

We also maintain directors' and officers’ liability insurance which covers certain liabilitiesunderwriters, of us, our directors, our officers who sign the registration statement and officers arising out of claims based on acts or omissions in their capacities as directors or officers,our controlling persons for some liabilities, including liabilities arising under the Securities Act.