As filed with the Securities and Exchange Commission on April 6, 2018November 3, 2023

Registration No. 333–            

333-

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORMS-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Proteostasis Therapeutics, Inc.KINETA, INC.

(Exact name of registrant as specified in its charter)

200 Technology Square, 4^th Floor

Cambridge, Massachusetts 02139219 Terry Ave. N., Suite 300

(617)225-0096Seattle, Washington 98109

(206) 378-0400

(Address, Including Zip Code, and Telephone Number, Including Area Code, of Registrant’s Principal Executive Offices)

Meenu ChhabraShawn Iadonato, Ph.D.

Chief Executive Officer

Proteostasis Therapeutics,Kineta, Inc.

200 Technology Square, 4^th Floor219 Terry Ave. N., Suite 300

Cambridge, Massachusetts 02139Seattle, WA 98109

(617)225-0096(206) 378-0400

(Name, Address, Including Zip Code, and Telephone Number, Including Area Code, of Agent for Service)

Copy to:

Mitchell S. Bloom, Esq.

John M. Mutkoski, Esq.

Sarah Ashfaq, Esq.

Goodwin Procter LLP

100 Northern Avenue

Boston, MA 02210

(617)570-1000

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this registration statement becomes effective.statement.

(Approximate Date of Commencement of Proposed Sale to the Public)

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following box.  box: ☐

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or interest reinvestment plans, check the following box.  box: ☒

If this Form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering. ☐

If this Form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box. ☐

If this Form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) under the Securities Act, check the following box. ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, anon-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company” and “emerging growth company” in Rule12b-2 of the Exchange Act.

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act. ☒☐

CALCULATION OF REGISTRATION FEE

THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTIONThe registrant hereby amends this registration statement on such date or dates as may be necessary to delay its effective date until the registrant shall file a further amendment which specifically states that this registration statement shall thereafter become effective in accordance with Section 8(a) OF THE SECURITIES ACT OF 1933, AS AMENDED, OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME EFFECTIVE ON SUCH DATE AS THE SECURITIES AND EXCHANGE COMMISSION, ACTING PURSUANT TO SAID SECTIONof the Securities Act, or until the registration statement shall become effective on such date as the Commission, acting pursuant to said Section 8(a), MAY DETERMINE.may determine.

THE INFORMATION IN THIS PROSPECTUS IS NOT COMPLETE AND MAY BE CHANGED. WE MAY NOT SELL THESE SECURITIES UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE COMMISSION IS EFFECTIVE. THIS PROSPECTUS IS NOT AN OFFER TO SELL THESE SECURITIES AND IS NOT SOLICITING AN OFFER TO BUY THESE SECURITIES IN ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

SUBJECT TO COMPLETION, DATED APRIL 6, 2018November 3, 2023

PROSPECTUS

KINETA, INC.

$100,000,000Up to 890,208 Shares of Common Stock

COMMON STOCKIssuable Upon Exercise of Outstanding Warrants

PREFERRED STOCK

DEBT SECURITIES

WARRANTS

UNITS

This prospectus will allow usrelates to issue,the resale from time to time, at prices and on terms to be determined at or prior toby the time of the offering, any combination of the securitiesselling securityholder(which term as used in this prospectus either individually orincludes its transferees, pledgees, distributees, donees and successors-in-interest) identified in units. We may also offerthis prospectus under the caption “Selling Securityholder,” of up to 890,208 shares of our common stock, or preferred stock upon conversion of the debt securities, common stock upon conversion of the preferred stock, or common stock, preferred stock or debt securitiespar value $0.001 (the “Common Stock”), that it may acquire upon the exercise of warrants. In addition, this prospectus may be usedoutstanding warrants, which we refer to offer securities foras the account“Warrants.” We issued the Warrants to the selling securityholder in a private placement concurrent (the “Private Placement”) with a registered direct offering (the “Registered Offering”) of persons other than us. 110,000 shares of our Common Stock and pre-funded warrants (“Pre-Funded Warrants”) to purchase up to an aggregate of 780,208shares of Common Stock, which was completed on October 5, 2023.

This prospectus provides you with a general description of such securities and the securities wegeneral manner in which the selling securityholder may offer. We will provide you withoffer or sell its securities. More specific terms of any offering in one or more supplements to this prospectus. This prospectussecurities that the selling securityholder may not be used to offer or sell our securities unless accompanied bymay be provided in a prospectus supplement. supplement that describes, among other things, the specific amounts and prices of the securities being offered and the terms of the offering. The prospectus supplement may also add, update or change information contained in this prospectus.

We are registering the securities described above for resale on behalf of the selling securityholder pursuant to the selling securityholder’s registration rights under the Securities Purchase Agreement (the “Purchase Agreement”), dated as of October 3, 2023, between Kineta and the institutional investor named therein. Our registration of the securities covered by this prospectus does not mean that either we or the selling securityholder will issue, offer or sell, as applicable, any of the securities. The selling securityholder may, from time to time, offer, sell or distribute all or a portion of the securities hereby registered publicly or through private transactions at prevailing market prices or at negotiated prices. See “Plan of Distribution” in this prospectus for more information. We will not receive any proceeds from the resale or other disposition of the shares of Common Stock by the selling securityholder. However, we will receive the proceeds of any cash exercise of the Warrants. See “Use of Proceeds” beginning on page 4 and “Plan of Distribution” beginning on page 4 of this prospectus for more information.

You should read this prospectus and any prospectus supplement as well as any documents incorporated by reference into this prospectus or any prospectus supplement,amendment carefully before you invest.invest in our securities.

Our common stockCommon Stock is listed on The NASDAQ GlobalNasdaq Stock Market, LLC under the symbol “PTI.”“KA”. On AprilNovember 2, 2018,2023, the last reported saleclosing price of our common stockCommon Stock was $4.69$4.39 per share. Prospective purchasers of our securities are urged to obtain current information as to the market prices of our securities, where applicable.

Investing in ourthese securities involves significant risks and uncertainties. You should review carefully the risks and uncertainties REFERRED TO under the heading “Risk Factors” beginning on page 4 of this prospectus, as well as the other information contained or incorporated by reference in this prospectus and ANY ACCOMPANYING prospectus supplement, before making a high degree of risk. Before deciding whetherdecision to invest in our securities, you should consider carefully the risks that we have described on page 3 of this prospectus under the caption “Risk Factors.” We may include specific risk factors in supplements to this prospectus under the caption “Risk Factors.”securities.

Our securities may be sold directly to investors, through agents designated from time to time or to or through underwriters or dealers. For additional information on the methods of sale, you should refer to the section entitled “Plan of Distribution” in this prospectus. If any underwriters or agents are involved in the sale of our securities with respect to which this prospectus is being delivered, the names of such underwriters or agents and any applicable commissions or discounts and over-allotment options will be set forth in a prospectus supplement. The price to the public of such securities and the net proceeds that we expect to receive from such sale will also be set forth in a prospectus supplement.

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

The date of this prospectus is , 2018.

TABLE OF CONTENTS

Table of Contents

ABOUT THIS PROSPECTUS

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission or SEC, utilizing(the “SEC”), using a “shelf” registration process. Under this shelf registration process, the selling securityholder may, from time to time, sell the securities offered by it described in this prospectus. We will not receive any proceeds from the shares of our common stock and preferred stock, various seriesCommon Stock offered by the selling securityholder under this prospectus. However, we will receive the proceeds of debt securities and/or warrantsany cash exercise of the Warrants.

Neither we nor the selling securityholder have authorized anyone to purchase any of such securities, either individually or in units, may be offered in one or more offerings. This prospectus providesprovide you with a general description of the securities that may be offered. Each time a typeany information or series of securities is offered underto make any representations other than those contained in this prospectus or any applicable prospectus supplement prepared by or on behalf of us or to which we have referred you. Neither we nor the selling securityholder take responsibility for, and can provide no assurance as to the reliability of, any other information that others may give you. Neither we nor the selling securityholder will make an offer to sell these securities in any jurisdiction where the offer or sale is not permitted.

We may also provide a prospectus supplement to the registration statement to add information to, or update or change information contained in, this prospectus. Any statement contained in this prospectus will be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained in such prospectus supplement modifies or supersedes such statement. Any statement so modified will be deemed to constitute a part of this prospectus only as so modified, and any statement so superseded will be deemed not to constitute a part of this prospectus. You should read both this prospectus and any applicable prospectus supplement to the registration statement together with the additional information to which we refer you in the sections of this prospectus entitled “Where You Can Find Additional Information” and “Incorporation by Reference.”

This prospectus incorporates by reference, and any prospectus supplement or free writing prospectus may contain specificand incorporate by reference, market data and industry statistics and forecasts that are based on independent industry publications and other publicly available information. Although we believe these sources are reliable, we do not guarantee the accuracy or completeness of this information and we have not independently verified this information. In addition, the market and industry data and forecasts that may be included or incorporated by reference in this prospectus, any prospectus supplement or any applicable free writing prospectus may involve estimates, assumptions and other risks and uncertainties and are subject to change based on various factors, including those discussed under the heading “Risk Factors” contained in this prospectus, the applicable prospectus supplement and any applicable free writing prospectus, and under similar headings in other documents that are incorporated by reference into this prospectus. Accordingly, investors should not place undue reliance on this information.

We are registering the securities described above for resale on behalf of the selling securityholder pursuant to the selling securityholder’s registration rights under the Purchase Agreement. Our registration of the securities covered by this prospectus does not mean that either we or the selling securityholder will issue, offer or sell, as applicable, any of the securities. The selling securityholder may, from time to time, offer, sell or distribute all or a portion of the securities hereby registered publicly or through private transactions at prevailing market prices or at negotiated prices. See “Plan of Distribution” in this prospectus for more information.

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SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus, any accompanying prospectus supplement and the information incorporated by reference in this prospectus contain certain statements that constitute “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended (the “Securities Act”), and Section 21E of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), and the “safe harbor” provisions of the United States Private Securities Litigation Reform Act of 1995. In some cases, you can identify these forward-looking statements by the use of terms such as “expect,” “will,” “continue,” “believe,” “estimate,” “aim,” “project,” “intend,” “should,” “is to be,” or similar expressions, and variations or negatives of these words, but the absence of these words does not mean that a statement is not forward-looking. All statements other than statements of historical fact are statements that could be deemed forward-looking statements. These forward-looking statements are subject to known and unknown risks, uncertainties and other factors that may cause our actual results, levels of activity, performance, or achievements to differ materially from results expressed or implied in this prospectus. The following factors, among others, could cause actual results to differ materially from those described in these forward-looking statements:

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The forward-looking statements contained in this prospectus are based on our current expectations and beliefs concerning future developments and their potential effects on our business. There can be no assurance that future developments affecting our business will be those that we have anticipated. These forward-looking statements involve a number of risks, uncertainties (some of which are beyond our control) or other assumptions that may cause actual results or performance to be materially different from those expressed or implied by these forward-looking statements. These risks and uncertainties include, but are not limited to, those factors described in the section entitled “Risk Factors” on page 4 of this prospectus. Moreover, we operate in a very competitive and rapidly changing environment.

New risks and uncertainties emerge from time to time and it is not possible for us to predict all such risk factors, nor can we assess the effect of all such risk factors on our business or the extent to which any factor or combination of factors may cause actual results to differ materially from those contained in any forward-looking statements. Should one or more of these risks or uncertainties materialize, or should any of the assumptions prove incorrect, actual results may vary in material respects from those projected in these forward-looking statements.

The forward-looking statements made by us in this prospectus and any accompanying prospectus supplement speak only as of the date of this prospectus and the accompanying prospectus supplement. Except to the extent required under the federal securities laws and rules and regulations of the SEC, we disclaim any obligation to update any forward-looking statement to reflect events or circumstances after the date on which the statement is made or to reflect the occurrence of unanticipated events. In light of these risks and uncertainties, there is no assurance that the events

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or results suggested by the forward-looking statements will in fact occur, and you should not place undue reliance on these forward-looking statements.

Although we undertake no obligation to revise or update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by law, you are advised to consult any additional disclosures we make in our Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and Current Reports on Form 8-K filed with the SEC. For information about the terms of that offering.where you can find these reports, see “Where You Can Find Additional Information” and “Incorporation by Reference.”

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PROTEOSTASIS THERAPEUTICS, INC.Kineta’s pipeline of assets and research interests includes (i) KVA12123, a monoclonal antibody, (“mAb”), immunotherapy targeting VISTA (V-domain Ig suppressor of T cell activation), and (ii) an anti-CD27 agonist mAb immunotherapy. These immunotherapies have the potential to address disease areas with unmet medical needs and significant commercial potential.

About Proteostasis Therapeutics, Inc.

We are an innovative,Kineta dosed the first patient in a Phase 1/2 clinical stage biopharmaceutical company committed to the discovery and developmenttrial of novel therapeutics to treat cystic fibrosis, or CF, and other diseases caused by an imbalanceKVA12123 in the proteostasis network,United States in April 2023. The ongoing Phase 1/2 clinical study is designed to evaluate KVA12123 alone and in combination with the immune checkpoint inhibitor pembrolizumab in patents with advance solid tumors. KVA12123 is engineered to be a setdifferentiated VISTA blocking immunotherapy to address the problem of pathways that control protein biosynthesis, folding, trafficking and clearance. The Company focuses on identifying therapies that restore protein function. CFimmunosuppression in the tumor microenvironment. It is a disease caused by defectsfully human engineered IgG1 monoclonal antibody that was designed to bind to VISTA through a unique epitope and across neutral and acidic pHs. KVA12123 may be an effective immunotherapy for many types of cancer, including non-small cell lung cancer (“NSCLC”), colorectal cancer (“CRC”), ovarian cancer (“OC”), renal cell carcinoma (“RCC”) and head and neck squamous cell carcinoma (“HNSCC”). These indications represent a significant unmet medical need with a large worldwide commercial opportunity for KVA12123.

Kineta is also conducting preclinical studies on its lead anti-CD27 agonist mAb immunotherapy that was discovered utilizing Kineta’s Innate Immunity Development Platform. This lead candidate is a fully human mAb that demonstrates low nanomolar (“nM”) binding affinity to CD27 in humans. In preclinical studies, Kineta’s lead anti-CD27 agonist mAb was observed to induce T cell proliferation and secretion of cytokines involved in T cell priming and recruitment, as well as NK cell activation, suggesting the function or abundance of cystic fibrosis transmembrane conductance regulator, or CFTR. Our CF focused pipeline consists of novel CFTR modulatorsability to potentiate new anti-tumor responses. CD27 is a clinically validated target that may be an effective immunotherapy for advanced solid tumors including correctors, potentiatorsRCC, CRC and amplifiers. Upon discovery of amplifiers, a novel class of CFTR modulators, we have exploitedOC. Kineta continues to conduct preclinical studies to optimize its novel mechanism of action as a drug screening toollead anti-CD27 agonist mAb clinical candidate and have subsequently identified correctors and potentiators to be developed as part of combination therapies. Investigational agents representative of all three classes of CFTR modulators are currentlyevaluate it in clinical development and includePTI-428, an amplifier, andPTI-801 a third generation corrector, both of which we believe are amenable foradd-on therapy tostandard-of-care CFTR modulator treatment andPTI-808, a potentiator intended to be developed as part of a dual combination withPTI-801 and a triple combination that also includesPTI-428 andPTI-801. We are developing and, if approved, intend to commercialize our own therapies, includingadd-on and combination therapies for CF patients who have at least one F508del mutation, representing the majority of the patient population. other checkpoint inhibitors.

RISK FACTORS

Investing in our securities involves risks. Yousignificant risks and uncertainties. Before deciding to purchase any of our securities, you should read carefully consider the risk factors containeddiscussion of risks and uncertainties under the heading “Risk Factors” in theour most recent Annual Report on Form 10-K and any subsequent Quarterly Reports on Form 10-Q, as well as any amendments thereto, which are incorporated by reference into this prospectus and any applicable prospectus supplement, and any related free writing prospectus for a specific offering of securities, as well as those incorporated by reference in this prospectus, before making an investment decision. You should also carefully considertogether with other information contained and incorporated by reference in this prospectus and any applicable prospectus supplement, including our financial statements and the related notes thereto incorporated by reference in this prospectus. The risks and uncertainties described in the applicable prospectus supplement and our other filings with the SECdocuments incorporated by reference herein are not the only onesand therein, and any free writing prospectus that we face.may authorize for use in connection with a specific offering. See “Where You Can Find Additional Information” and “Incorporation by Reference.”

We could be materially and adversely affected by any or all of these risks or by additional risks and uncertainties not presently known to us or that we currently considerdeem immaterial that may also adversely affect us. If any of the described risks occur, our business, financial condition or results of operations could be materially harmed. In such case, the value of our securities could decline and you may lose all or part of your investment.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

The SEC encourages companies to disclose forward-looking information so that investors can better understand a company’s future prospects and make informed investment decisions. This prospectus and the documents we have filed with the SEC that are incorporated herein by reference contain such “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995.

Words such as “may,” “anticipate,” “estimate,” “expects,” “projects,” “intends,” “plans,” “believes,” “tracking” and words and terms of similar substance used in connection with any discussion of future operating or financial performance, identify forward-looking statements. Forward-looking statements represent management’s present judgment regarding future events and are subject to a number of risks and uncertainties that could cause actual results to differ materially from those described in the forward-looking statements. These risks include, but are not limited to, risks and uncertainties regarding our preclinical and clinical studies, our ability to conduct clinical trials of our product candidates and the results of such trials, as well as risks and uncertainties relating to litigation, government regulation and third-party reimbursement, economic conditions, markets, products, competition, intellectual property, services and prices, key employees, future capital needs and other factors. Please also see the discussion of risks and uncertainties under the caption “Risk Factors” contained in any supplements to this prospectus and in our most recent annual report on Form10-K, as revised or supplemented by our most recent quarterly report on Form10-Q, as well as any amendments thereto, as filed with the SEC and which are incorporated herein by reference.

In light of these assumptions, risks and uncertainties, the results and events discussed in the forward-looking statements contained in this prospectus or in any document incorporated herein by reference might not occur. Investors are cautioned not to place undue reliance on the forward-looking statements, which speak only as of the date of this prospectus or the date of the document incorporated by reference in this prospectus. We are not under any obligation, and we expressly disclaim any obligation, to update or alter any forward-looking statements, whether as a result of new information, future events or otherwise. All subsequent forward-looking statements attributable to us or to any person acting on our behalf are expressly qualified in their entirety by the cautionary statements contained or referred to in this section.

RATIO OF EARNINGS TO FIXED CHARGES

Our ratio of earnings to fixed charges for each of the five most recently completed fiscal years and any required interim periods will each be specified in a prospectus supplement or in a document that we file with the SEC and incorporate by reference pertaining to the issuance, if any, by us of debt securities or preference securitiesparticular offering in the future.

USE OF PROCEEDS

We will retain broad discretion over the use of the netnot receive any proceeds from the sale of shares of Common Stock offered by the securities offered hereby. Except as provided inselling securityholder under this prospectus. However, we will receive the applicable prospectus supplement orproceeds of any related free writing prospectus thatcash exercise of the Warrants. If all of the Warrants were exercised for cash, we may authorize to be provided to you, wewould receive aggregate proceeds of approximately $2.9 million. We intend to use the net proceeds from the saleany cash exercise of the securities by us through this prospectusWarrants for general corporate purposes, which may include funding research, clinical development, including for KVA12123, working capital, capital expenditures working capital and other general corporate purposes.

PLAN OF DISTRIBUTION

The selling securityholder may offer and administrative expenses. Wesell, from time to time, the shares of Common Stock issuable upon exercise of the Warrants. The selling securityholder will act independently of us in making decisions with respect to the timing, manner and size of each sale. Such sales may also usebe made on one or more exchanges or in the over-the-counter market or otherwise, at prices and under terms then prevailing or at prices related to the then current market price or in negotiated transactions. The selling securityholder may sell its securities by one or more of, or a combination of, the following methods:

In addition, any securities that qualify for sale pursuant to Rule 144 may be sold under Rule 144, or pursuant to other available exemptions from the registration requirements under the Securities Act, rather than pursuant to this prospectus. We

The selling securityholder may set the price or prices of its securities at:

To the extent required, this prospectus may be amended or supplemented from time to time to describe a specific plan of distribution. In connection with distributions of the securities or otherwise, the selling securityholder may enter into hedging transactions with broker-dealers or other financial institutions. In connection with such transactions, broker-dealers or other financial institutions may engage in short sales of the securities in the course of hedging the positions they assume with selling securityholder. The selling securityholder may also sell the securities short and redeliver the securities to close out such short positions.

The selling securityholder may also enter into option or other transactions with broker-dealers or other financial institutions 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 securityholder may also pledge securities to a broker-dealer or other financial institution, and, upon a default, such broker-dealer or other financial institution, may effect sales of the pledged securities pursuant to this prospectus (as supplemented or amended to reflect such transaction).

The selling securityholder may elect to make an in-kind distribution of Common Stock to its members, partners or shareholders pursuant to the registration statement of which this prospectus is a part by delivering a prospectus. To the extent that such members, partners or shareholders are not affiliates of ours, such members, partners or shareholders would thereby receive freely tradable shares of Common Stock pursuant to the distribution through a registration statement.

The selling securityholder may also pledge securities to a broker-dealer or other financial institution, and, upon a default, such broker-dealer or other financial institution may effect sales of the pledged securities pursuant to this prospectus (as supplemented or amended to reflect such transaction).

The selling securityholder may enter into derivative transactions with third parties, or sell securities not covered by this prospectus to third parties in privately negotiated transactions. If the applicable prospectus supplement indicates, in connection with those derivatives, the third parties may sell securities covered by this prospectus and the applicable prospectus supplement, including in short sale transactions. If so, the third party may use securities pledged by the selling securityholder or borrowed from the selling securityholder or others to settle those sales or to close out any related open borrowings of stock, and may use securities received from the selling securityholder in settlement of those derivatives to close out any related open borrowings of stock. The third party in such sale transactions will set forthbe an underwriter and will be identified in the applicable prospectus supplement (or a post-effective amendment). In addition, the selling securityholder may otherwise loan or free writingpledge securities to a financial institution or other third party that in turn may sell the securities short using this prospectus. Such financial institution or other third party may transfer its economic short position to investors in our securities or in connection with a concurrent offering of other securities.

In effecting sales, broker-dealers or agents engaged by the selling securityholder may arrange for other broker-dealers to participate. Broker-dealers or agents may receive commissions, discounts or concessions from the Selling Securityholder in amounts to be negotiated immediately prior to the sale.

In offering the securities covered by this prospectus, our intended usethe selling securityholder and any broker-dealers who execute sales for the net proceeds receivedselling securityholder may be deemed to be “underwriters” within the meaning of the Securities Act in connection with such sales. Any profits realized by the selling securityholder and the compensation of any broker-dealer may be deemed to be underwriting discounts and commissions.

In order to comply with the securities laws of certain states, if applicable, the securities must be sold in such jurisdictions only through registered or licensed brokers or dealers. In addition, in certain states the securities may not be sold unless they have been registered or qualified for sale in the applicable state or an exemption from the registration or qualification requirement is available and is complied with.

We will make copies of this prospectus available to the selling securityholder for the purpose of satisfying the prospectus delivery requirements of the Securities Act. The selling securityholder may indemnify any broker-dealer that participates in transactions involving the sale of the securities against certain liabilities, including liabilities arising under the Securities Act.

At the time a particular offer of securities is made, if required, a prospectus supplement will be distributed that will set forth the number of securities being offered and the terms of the offering, including the name of any securities sold pursuantunderwriter, dealer or agent, the purchase price paid by any underwriter, any discount, commission and other item constituting compensation, any discount, commission or concession allowed or reallowed or paid to any dealer, and the proposed selling price to the prospectus supplementpublic.

Certain agents, underwriters and dealers, and their associates and affiliates, may be customers of, have borrowing relationships with, engage in other transactions with, or free writing prospectus. Pending these uses, we intend to investperform services, including investment banking services, for us or one or more of our respective affiliates and/or the net proceedsselling securityholder or one or more of its respective affiliates in short-term obligationsthe ordinary course of the U.S. treasury securities and U.S. government-sponsored enterprise securities.

Registration RightsExercisability

The holdersWarrants became exercisable immediately following issuance and have a term of 6,831,803 shares of our common stock, or their permitted transferees, are entitled to rights with respect to the registration of these securities under the Securities Act. These rights are provided under the terms of a stockholders’ agreement between usfive and the holders of our preferred stock. The stockholders’ agreement includes demand registration rights, short-form registration rights and piggyback registration rights. All fees, costs and expenses of underwritten registrations under the stockholders’ agreement will be borne by us and all selling expenses, including underwriting discounts and selling commissions, will be borne by the holders of the shares being registered.

Demand Registration Rights

The holders of 6,831,803 shares of our common stock, including shares issuable upon the conversion of preferred stock or their permitted transferees, are entitled to demand registration rights. Under the terms of the stockholders’ agreement, we will be required, upon the written request of holders oftwo-thirds of these securities, to use our best efforts to file a registration statement and use reasonable, diligent efforts to effect the registration of all or a portion of these shares for public resale. We are required to effect only two registrations pursuant to this provision of the stockholders’ agreement.

Short Form Registration Rights

The holders of 6,831,803 shares of our common stock, or their permitted transferees, are also entitled to short form registration rights. Pursuant to the stockholders’ agreement, if we are eligible to file a registration statement on FormS-3, upon the written request of any of these holders to sell registrable securities at an aggregate price of at least $1,000,000, we will be required to use our best efforts to affect a registration of such shares. We are required to effect only two registrations in any twelve month period pursuant to this provision of the stockholders’ agreement.

Piggyback Registration Rights

The holders of 6,831,803 shares of our common stock, or their permitted transferees, are entitled to piggyback registration rights. If we register any of our securities either for our own account or for the account of other security holders, the holders of these shares are entitled to include their shares in the registration. Subject to certain exceptions contained in the stockholders’ agreement, we and the underwriters may limit the number of shares included in the underwritten offering if the underwriters determine in good faith that marketing factors require a limitation of the number of shares to be underwritten.

Indemnification

Our stockholders’ agreement contains customary cross-indemnification provisions, under which we are obligated to indemnify holders of registrable securities in the event of material misstatements or omissions in the registration statement attributable to us, and they are obligated to indemnify us for material misstatements or omissions attributable to them.

Expiration of Registration Rights

The registration rights granted under the investor rights agreement will terminate upon the earlier of (i) a deemed liquidation event, as defined in our amended and restated certificate of incorporation or (ii) at such time when all registrable securities could be sold without restriction under Rule 144 of the Securities Act.

Antitakeover Effects of Delaware Law and Provisions of our Amended and Restated Certificate of Incorporation and Amended and RestatedBy-laws

Certain provisions of the Delaware General Corporation Law and of our amended and restated certificate of incorporation and amended and restatedby-laws could have the effect of delaying, deferring or discouraging another party from acquiring control of us. These provisions, which are summarized below, are expected to discourage certain types of coercive takeover practices and inadequate takeover bids and, as a consequence, they might also inhibit temporary fluctuations in the market price of our common stock that often result from actual or rumored hostile takeover attempts. These provisions are also designed in part to encourage anyone seeking to acquire control of us to first negotiate with our board of directors. These provisions might also have the effect of preventing changes in our management. It is possible that these provisions could make it more difficult to accomplish transactions that stockholders might otherwise deem to be in their best interests. However, we believe that the advantages gained by protecting our ability to negotiate with any unsolicited and potentially unfriendly acquirer outweigh the disadvantages of discouraging such proposals, including those priced above the then-current market value of our common stock, because, among other reasons, the negotiation of such proposals could improve their terms.

Delaware Takeover Statute

We are subject to the provisions of Section 203 of the Delaware General Corporation Law. In general, Section 203 prohibits a publicly held Delaware corporation from engaging in a “business combination” with an “interested stockholder” for a three-year period following the time that this stockholder becomes an interested stockholder, unless the business combination is approved in a prescribed manner. Under Section 203, a business combination between a corporation and an interested stockholder is prohibited unless it satisfies one of the following conditions:

Section 203 defines a business combination to include:

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

Provisions of our Amended and Restated Certificate of Incorporation and Amended and RestatedBy-laws

Our amended and restated certificate of incorporation and amended and restatedby-laws include a number of provisions that may have the effect of delaying, deferring or discouraging another party from acquiring control of us and encouraging persons considering unsolicited tender offers or other unilateral takeover proposals to negotiate with our board of directors rather than pursuenon-negotiated takeover attempts. These provisions include the items described below.

Board composition and filling vacancies.In accordance with our amended and restated certificate of incorporation, our board is divided into three classes serving staggered three-year terms, with one class being elected each year. Our amended and restated certificate of incorporation also provides that directors may be removed only for cause and then only by the affirmative vote of the holders of 75% or more of the shares then entitled to vote at an election of directors. Furthermore, any vacancy on our board of directors, however occurring, including a vacancy resulting from an increase in the size of our board, may only be filled by the affirmative vote of a majority of our directors then in office even if less than a quorum.

No written consent of stockholders.Our amended and restated certificate of incorporation provides that all stockholder actions are required to be taken by a vote of the stockholders at an annual or special meeting, and that stockholders may not take any action by written consent in lieu of a meeting. This limit may lengthen the amount of time required to take stockholder actions and would prevent the amendment of ourby-laws or removal of directors by our stockholder without holding a meeting of stockholders.

Meetings of stockholders.Our amended and restatedby-laws provide that only a majority of the members of our board of directors then in office may call special meetings of stockholders and only those matters set forth in the notice of the special meeting may be considered or acted upon at a special meeting of stockholders. Our amended and restatedby-laws limit the business that may be conducted at an annual meeting of stockholders to those matters properly brought before the meeting.

Advance notice requirements.Our amended and restatedby-laws establish advance notice procedures with regard to stockholder proposals relating to the nomination of candidates for election as directors or new business to be brought before meetings of our stockholders. These procedures provide that notice of stockholder proposals must be timely given in writing to our corporate secretary prior to the meeting at which the action is to be taken. Generally, to be timely, notice must be received at our principal executive offices not less than 90 days or more than 120 days prior to the first anniversary date of the annual meeting for the preceding year. The notice must contain certain information specified in our amended and restatedby-laws.

Amendment to certificate of incorporation andby-laws.As required by the Delaware General Corporation Law, any amendment of our amended and restated certificate of incorporation must first be approved by a majority of our board of directors, and if required by law or our amended and restated certificate of incorporation, must thereafter be approved by a majority of the outstanding shares entitled to vote on the amendment, and a majority of the outstanding shares of each class entitled to vote thereon as a class, except that the amendment of the provisions relating to stockholder action, directors, limitation of liability and the amendment of our amended and restated certificate of incorporation must be approved by not less than 75% of the outstanding shares entitled to vote on the amendment, and not less than 75% of the outstanding shares of each class entitled to vote thereon as a class. Our amended and restatedby-laws may be amended by the affirmative vote of a majority vote of the directors then in office, subject to any limitations set forth in the amended and restatedby-laws; and may also be amended by the affirmative vote of at least 75% of the outstanding shares entitled to vote on the amendment, or, if the board of directors recommends that the stockholders approve the amendment, by the affirmative vote of the majority of the outstanding shares entitled to vote on the amendment, in each case voting together as a single class.

Undesignated preferred stock.Our amended and restated certificate of incorporation provides for authorized shares of preferred stock. The existence of authorized but unissued shares of preferred stock may enable our board of directors to render more difficult or to discourage an attempt to obtain control of us by means of a merger, tender offer, proxy contest or otherwise. For example, if in the due exercise of its fiduciary obligations, our board of directors were to determine that a takeover proposal is not in the best interests of us or our stockholders, our board of directors could cause shares of preferred stock to be issued without stockholder approval in one or more private offerings or other transactions that might dilute the voting or other rights of the proposed acquirer or insurgent stockholder or stockholder group. In this regard, our amended and restated certificate of incorporation grants our board of directors broad power to establish the rights and preferences of authorized and unissued shares of preferred stock. The issuance of shares of preferred stock could decrease the amount of earnings and assets available for distribution to holders of shares of common stock. The issuance may also adversely affect the rights and powers, including voting rights, of these holders and may have the effect of delaying, deterring or preventing a change in control of us.

Choice of forum.Our amended and restatedby-laws provide that the Court of Chancery of the State of Delaware is the sole and exclusive forum for any derivative action or proceeding brought on our behalf, any action asserting a breach of fiduciary duty, any action asserting a claim against us arising pursuant to the Delaware General Corporation Law, our certificate of incorporation or ourby-laws, or any action asserting a claim against us that is governed by the internal affairs doctrine. Although our amended and restatedby-laws contain the choice of forum provision described above, it is possible that a court could rule that such a provision is inapplicable for a particular claim or action or that such provision is unenforceable.

Limitations on Liability and Indemnification of Officers and Directors.Our amended and restated certificate of incorporation and amended and restatedby-laws limit the liability of our officers and directors to the fullest extent permitted by the Delaware General Corporation Law and provides that we will indemnify them to the fullest extent permitted by such law.

Transfer Agent and Registrar

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

The NASDAQ Global Market

Our common stock is listed for quotation on The NASDAQ Global Market under the symbol “PTI.” On April 2, 2018 the last reported sale price of our common stock was $4.69 per share.

DESCRIPTION OF DEBT SECURITIES

The following description, together with the additional information we include in any applicable prospectus supplements, summarizes the material terms and provisions of the debt securities that may be offered under this prospectus. While the terms we have summarized below will apply generally to any future debt securities that may be offered pursuant to this prospectus, we will describe the particular terms of any debt securities that may be offered in more detail in the applicable prospectus supplement. If we so indicate in a prospectus supplement, the terms of any debt securities offered under that prospectus supplement may differone-half (5.5) years from the terms we describe below, and to the extent the terms set forth in a prospectus supplement differ from the terms described below, the terms set forth in the prospectus supplement shall control.

Under this prospectus, debt securities, which may be senior or subordinated, may be sold from time to time, in one or more offerings. We will issue any such senior debt securities under a senior indenture that we will enter into with a trustee to be named in the senior indenture. We will issue any such subordinated debt securities under a subordinated indenture, which we will enter into with a trustee to be named in the subordinated indenture. We have filed forms of these documents as exhibits to the registration statement, which includes this prospectus. We use the term “indentures” to refer to both the senior indenture and the subordinated indenture.initial exercise date. The indentures will be qualified under the Trust Indenture Act of 1939, as in effect on the date of the indenture, or the Trust Indenture Act. We use the term “debenture trustee” to refer to either the trustee under the senior indenture or the trustee under the subordinated indenture, as applicable.

The following summaries of material provisions of the senior debt securities, the subordinated debt securities and the indenturesWarrants are subject to, and qualified in their entirety by reference to, all the provisions of the indenture applicable to a particular series of debt securities.

General

Each indenture provides that debt securities may be issued from time to time in one or more series and may be denominated and payable in United States dollars or foreign currencies or units based on or relating to United States dollars or foreign currencies, including euros. Neither indenture limits the amount of debt securities that may be issued thereunder, and each indenture provides that the specific terms of any series of debt securities shall be set forth in, or determined pursuant to, an authorizing resolution and/or a supplemental indenture, if any, relating to such series.

We will describe in each prospectus supplement the following terms relating to a series of debt securities:

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

Conversion or Exchange Rights

We will set forth in the prospectus supplement the terms, if any, 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 whether conversion or exchange is mandatory,exercisable, at the option of the holder, in whole or in part by delivering to us a duly executed exercise notice and, at our option. We may include provisions pursuant to whichany time a registration statement registering the issuance of shares of Common Stock underlying the Warrants under the Securities Act is effective and available for the issuance of such shares, or an exemption from registration under the Securities Act is available for the issuance of such shares, by payment in full in immediately available funds for the number of shares of our common stockCommon Stock purchased upon such exercise. If at the time of exercise there is no effective registration statement registering, or our other securities that the holdersprospectus contained therein is not available for the issuance of the seriesshares of debt securitiesCommon Stock underlying the Warrants, then the Warrants may also be exercised, in whole or in part, at such time by means of a cashless exercise, in which case the holder would receive upon such exercise the net number of shares of Common Stock determined according to the formula set forth in the Warrant.

Exercise Limitation

A holder will not have the right to exercise any portion of the Warrants if the holder (together with its affiliates) would beneficially own in excess of 4.99% (or, upon election of the holder, 9.99%) of the number of our shares of Common Stock outstanding immediately after giving effect to the exercise, as such percentage ownership is determined in accordance with the terms of the Warrants. However, any holder may increase or decrease such percentage, but in no event may such percentage be increased to more than 9.99%, provided that any increase will not be effective until the 61st day after such election.

Exercise Price Adjustment

The exercise price of the Warrants is subject to adjustment.appropriate adjustment in the event of certain stock dividends and distributions, stock splits, stock combinations, reclassifications or similar events affecting our shares of Common Stock.

Consolidation, MergerTransferability

Subject to applicable laws, the Warrants may be offered for sale, sold, transferred or Sale; No Protectionassigned without our consent.

Exchange Listing

There is no established trading market for the Warrants, and we do not expect a market to develop. In addition, we do not intend to apply for the listing of the Warrants on any national securities exchange or other trading market.

Fundamental Transactions

In the event of any fundamental transaction, as described in Event of a Change of Controlthe Warrants and generally including any merger with or Highly Leveraged Transaction

The indentures may not contain any covenant that restricts our ability to merge or consolidate, or sell, convey, transfer or otherwise disposeinto another entity, sale of all or substantially all of our assets. However,assets, tender offer or exchange offer, or reclassification of our shares of Common Stock, then upon any successorsubsequent exercise of a Warrant, the holder will have the right to or acquirerreceive as alternative consideration, for each share of Common Stock that would have been issuable upon such exercise immediately prior to the occurrence of such assets will be required to assume allfundamental transaction, the number of shares of Common Stock of the successor or acquiring corporation of our obligations undercompany, if it is the indenturessurviving corporation, and any additional consideration receivable upon or the debt securities, as appropriate.

Unless we state otherwise in the applicable prospectus supplement, the debt securities will not contain any provisions that may afford holdersa result of such transaction by a holder of the debt securities protection innumber of shares of Common Stock for which the event we have a change of control orWarrant is exercisable immediately prior to such event.

Notwithstanding the foregoing, in the event of a highly leveragedfundamental transaction, (whetherwe or not sucha successor entity shall, at the holder’s option, exercisable at any time concurrently or within thirty (30) days following the consummation of a fundamental transaction, resultspurchase the Warrant by paying to the holder an amount equal to the Black Scholes Value (as defined in a change of control), which could adversely affect holders of debt securities.

Events of Default Under the Indenture

The following will be events of default under the indentures with respect to any series of debt securities that we may issue:

No event of default with respect to a particular series of debt securities (except as to certain events of bankruptcy, insolvency or reorganization) necessarily constitutes an event of default with respect to any other series of debt securities. The occurrence of an event of default may constitute an event of default under any bank credit agreements we may have in existence from time to time. In addition, the occurrence of certain events of default or an acceleration under the indenture may constitute an event of default under certain of our other indebtedness outstanding from time to time.

If an event of default with respect to debt securities of any series at the time outstanding occurs and is continuing, then the trustee or the holders of not less than a majority in principal amount of the outstanding debt securities of that series may, by a notice in writing to us (and to the debenture trustee if given by the holders), declare to be due and payable immediately the principal (or, if the debt securities of that series are discount securities, thatremaining unexercised portion of the principal amount as may be specified inWarrant on the terms of that series) of and premium and accrued and unpaid interest, if any, on all debt securities of that series. Before a judgment or decree for paymentdate of the money due has been obtained with respect to debt securities of any series,fundamental transaction. If the holders of a majority in principal amount of the outstanding debt securities of that series (or, at a meeting of holders of such series at which a quorumfundamental transaction is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) may rescind and annul the acceleration if all events of default, other than thenon-payment of accelerated principal, premium, if any, and interest, if any, with respect to debt securities of that series, have been cured or waived as provided in the applicable indenture (including payments or deposits in respect of principal, premium or interest that had become due other than as a result of such acceleration). We refer you to the prospectus supplement relating to any series of debt securities that are discount securities for the particular provisions relating to acceleration of a portion of the principal amount of such discount securities upon the occurrence of an event of default.

Subject to the terms of the indentures, if an event of default under an indenture shall occur and be continuing, the debenture trustee will be under no obligation to exercise any of its rights or powers under such indenture at the request or direction of any ofnot within our control, the holders of the applicable seriesWarrants will only be entitled to receive from us or a successor entity the same type or form of debt securities, unless such holders have offeredconsideration (and in the debenture trustee reasonable indemnity. The holders of a majority in principal amountsame proportion), at the Black Scholes Value of the outstanding debt securitiesunexercised portion of any series will have the right to direct the time, methodWarrant, that is being offered and place of conducting any proceeding for any remedy available to the debenture trustee or exercising any trust or power conferred on the debenture trustee, with respect to the debt securities of that series, provided that:

These limitationsWarrant will not apply to a suit instituted byhave the rights or privileges of a holder of debtour Common Stock, including any voting rights, until the holder exercises the warrant.

Resale Registration Rights

We have filed this registration statement with the SEC that includes this prospectus to register for resale under the Securities Act, the shares of Common Stock issuable upon exercise of the Warrants to satisfy our obligations in connection with the Private Placement under the Purchase Agreement. We will use commercially reasonable efforts to keep the registration statement effective at all times until the selling securityholder no longer owns any Warrants or shares issuable upon exercise thereof.

SELLING SECURITYHOLDER

This prospectus relates to the resale by the selling securityholder from time to time of up to an aggregate of 890,208 shares of Common Stock issuable upon the exercise of our outstanding Warrants.

The selling securityholder acquired its securities if we default in the payment of the principal, premium, if any, or interest on, the debt securities.

We will periodically file statementsPrivate Placement concurrent with the applicable debenture trustee regardingRegistered Offering of 110,000 shares of our compliance with specified covenants in the applicable indenture.

ModificationCommon Stock and Pre-Funded Warrants to purchase up to an aggregate of Indenture; Waiver780,208 shares of Common Stock, which was completed on October 5, 2023.

The debenture trustee and we may changeWarrants held by the applicable indenture without the consent of any holders with respect to specific matters, including:

In addition, under the indentures, the rights of holders of a series of debt securities may be changed by us and the debenture trustee with the written consent ofselling securityholder contain limitations which prevent the holders from exercising such Warrants if such exercise would cause the selling securityholder, together with certain related parties, to beneficially own a number of at least a majority in aggregate principal amountshares of the outstanding debt securities of each seriesCommon Stock which would exceed 4.99% (or, at a meeting of holders of such series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) that is affected. However, the debenture trustee and we may make the following changes only with the consent of each holder of any outstanding debt securities affected:

Except for certain specified provisions, the holders of at least a majority in principal amount of the outstanding debt securities of any series (or, at a meeting of holders of such series at which a quorum is present, the holders of a majority in principal amount of the debt securities of such series represented at such meeting) may on behalf of the holders of all debt securities of that series waive our compliance with provisions of the indenture. The holders of a majority in principal amount of the outstanding debt securities of any series may on behalf of the holders of all the debt securities of such series waive any past default under the indenture with respect to that series and its consequences, except a default in the payment of the principal of, premium or any interest on any debt security of that series or in respect of a covenant or provision, which cannot be modified or amended without the consentelection of the holder, 9.99%) of eachour then outstanding debt securityCommon Stock following such exercise, excluding for purposes of such determination, shares of Common Stock issuable upon exercise of the series affected; provided, however,Warrants which have not been exercised.

The following table sets forth information relating to the selling securityholder as of October 31, 2023. For purposes of this table, we have assumed that the holders of a majority in principal amountselling securityholder will have sold all of the outstanding debt securities of any series may rescind an acceleration and its consequences, including any related payment default that resulted fromcovered by this prospectus upon the acceleration.

Discharge

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

In order to exercise our rights to be discharged with respect to a series, we will have to 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 Transferoffering.

We cannot advise you as to whether the selling securityholder will issuein fact sell any or all of such securities. In particular, the debtselling securityholder may have sold, transferred or otherwise disposed of all or a portion of its securities after the date on which it provided us with information regarding its securities. Any changed or new information given to us by the selling securityholder, including regarding the identity of, each series only in fully registered form without coupons and unless we otherwise specify in the applicable prospectus supplement, in denominations of $1,000 and any integral multiple thereof. The indentures provide that we may issue debt securities of a series in temporary or permanent global form and as book-entry securities thatheld by, the selling securityholder, will be deposited with, or on behalf of, The Depository Trust Company or another depositary named by us and identifiedset forth in a prospectus supplement with respect to that series.

At the option of the holder, subject to the terms of the indentures 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 indentures 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 or in the applicable indenture, we will make 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 Debenture Trustee

The debenture trustee other than during the occurrence and continuance of an event of default under the applicable indenture, will undertake to perform only those duties as are specifically set forth in the applicable indenture. Upon an event of default under an indenture, the debenture trustee under such indenture 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 debenture trustee is under no obligation to exercise any of the powers given it by the indentures 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 indicate otherwise in the applicable prospectus supplement, on any interest payment date, we will pay the interest on any debt securities to the person in whose name such 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, will we make interest payments by check which we will mail to the holder. Unless we otherwise indicate in a prospectus supplement, we will designate the corporate trust office of the debenture trustee in the City of New York 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 debenture trustee for the payment of the principal of or any premium or interest on any debt securities which 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 security thereafter may look only to us for payment thereof.

Governing Law

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

Subordination of Subordinated Debt Securities

Our obligations pursuant to any subordinated debt securities will be unsecured and will be subordinate and junior in priority of payment to certain of our other indebtedness to the extent described in a prospectus supplement. The subordinated indenture does not limit the amount of senior indebtedness we may incur. It also does not limit us from issuing any other secured or unsecured debt.

DESCRIPTION OF WARRANTS

Warrants to purchase shares of our common stock, preferred stock and/or debt securities in one or more series together with other securities or separately may be offered, as described in the applicable prospectus supplement. Below is a description of certain general terms and provisions of the warrants that may be offered. Particular terms of the warrants will be described in the warrant agreements and the prospectus supplement to the warrants.

The applicable prospectus supplement will contain, where applicable, the following terms of and other information relating to the warrants:

DESCRIPTION OF UNITS

Units consisting of common stock, preferred stock, debt securities and/or warrants for the purchase of common stock, preferred stock and/or debt securities in one or more series may be offered. In this prospectus, we have summarized certain general features of the units. We urge you, however, to read the prospectus supplements related to the series of units being offered, as well as the unit agreements that contain the terms of the units. We will file as exhibits to an amendmentamendments to the registration statement of which this prospectus is a part, or will incorporate by reference from a current reportif and when necessary.

Please see the section entitled “Plan of Distribution” for further information regarding the selling securityholder’s method of distributing these securities.

Beneficial ownership of the selling securityholder is determined in accordance with Rule 13d-3(d) under the Exchange Act. The percentage of shares beneficially owned prior to, and after, the offering is based on Form8-K that we file with10,393,567 shares of Common Stock outstanding as of October 31, 2023.

As used in this prospectus, the SEC, as applicable,term “selling securityholder” includes the form of unit agreementselling securityholder listed in the table below and any supplemental agreements that describeof its transferees, pledgees, distributees, donees and successors.

LEGAL MATTERS

The validity of the securities offered hereby have been passed upon for us by Orrick, Herrington & Sutcliffe LLP. Any underwriters or agents will be advised about other issues relating to the offering by counsel to be named in the applicable prospectus supplement relating to a particular series of units.

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. The securities may be distributed from time to time in one or more transactions:supplement.

EXPERTS

We may also sell equity securities covered by this registration statement in an “at the market offering”Kineta, Inc. as defined in Rule 415 under the Securities Act. Such offering may be made into an existing trading marketof December 31, 2022 and 2021 and for such securities in transactions at other than a fixed price, either:

Suchat-the-market offerings, if any, may be conducted by underwriters acting as principal or agent.

Each time we offer and sell securities hereto, we will provide a prospectus supplement (and any related free writing prospectus that we may authorize to be provided to you) that will set forth the terms of the offering of the securities, including:

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, other than securities covered by any over-allotment option. Any public offering price and any discounts or concessions allowed orre-allowed or paid to dealers may change from time to time. We may use underwriters with whom we have a material relationship. The prospectus supplement, naming the underwriter, will describe the nature of any such relationship.

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

We may authorize agents or underwriters to solicit offers by certain purchasers 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. The prospectus supplement will set forth the conditions to these contracts and any commissions we must pay for solicitation of these contracts.

We may provide agents and underwriters with indemnification against civil liabilities, 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.

Any securities we may 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 over-allotment, stabilizing transactions, short-covering transactions and penalty bids in accordance with Regulation M under the Exchange Act. Over-allotment 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 price. Syndicate-covering or other short-covering transactions involve purchases of the securities, either through exercise of the over-allotment option or 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 dealer 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.

Any underwriters that are qualified market makers on The NASDAQ Global Market may engage in passive market making transactions in the common stock on The NASDAQ Global Market in accordance with Regulation M under the Exchange Act, during the business day prior to the pricing of the offering, before the commencement of offers or sales of the common stock. 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 musttwo years 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.

LEGAL MATTERS

Goodwin Procter LLP, Boston, Massachusetts, will pass upon the validity of the issuance of the securities offered by this prospectus.

EXPERTS

The financial statementsended, incorporated in this prospectus by reference to the Annual Report on Form10-K for the year ended December 31, 20172022, have been so incorporated in reliance on the report (which contains an explanatory paragraph relating to the Company’s ability to continue as a going concern as described in Note 1 to the financial statements) of PricewaterhouseCoopersaudited by Marcum LLP, an independent registered public accounting firm, given onas stated in their report thereon, included therein, and incorporated by reference in the prospectus and registration statement in reliance upon such report and upon the authority of saidsuch firm as experts in auditingaccounting and accounting.auditing.

WHERE YOU CAN FIND MOREADDITIONAL INFORMATION

We are subject to the reporting requirements of the Securities Exchange Act of 1934, as amended, and file annual, quarterly and current reports, proxy statements and other information with the SEC. You may readThe SEC maintains an internet website at http://www.sec.gov that contains periodic and copy thesecurrent reports, proxy and information statements, and other information atregarding registrants that file electronically with the SEC’s public reference facilities at 100 F Street, N.E., Room 1580, Washington, D.C. 20549. You can request copiesSEC. Copies of these documentscertain information filed by writing tous with the SEC and paying a fee for the copying cost. Please call the SEC at1-800-SEC-0330 for more information about the operation of the public reference facilities. SEC filings are also available on our website at the SEC’s web site at http:https://www.sec.gov.kinetabio.com/. Our common stockwebsite is listed on The NASDAQ Global Market,not a part of this prospectus and you can read and inspect our filings at the offices of the Financial Industry Regulatory Authority at 1735 K Street, Washington, D.C. 20006.is not incorporated by reference in this prospectus.

This prospectus is only part of a registration statement on FormS-3 that we have filed with the SEC under the Securities Act and thereforeSEC. This prospectus omits certainsome information contained in the registration statement. We have also filedstatement in accordance with SEC rules and regulations. You should review the information and exhibits and schedules within the registration statement thatfor further information on us and our consolidated subsidiaries and the securities we are excluded fromoffering. Statements in this prospectus and you should referconcerning any document we filed as an exhibit to the applicable exhibit or schedule for a complete description of any statement referring to any contract or other document. You may inspect a copy of the registration statement including the exhibits and schedules, without charge, at the public reference room or obtain a copy fromthat we otherwise filed with the SEC upon payment ofare not intended to be comprehensive and are qualified by reference to these filings. You should review the fees prescribed by the SEC.complete document to evaluate these statements.

We also maintain a website at www.proteostasis.com, through which you can access our SEC filings. The information set forth on our website is not part of this prospectus.

INCORPORATION OF DOCUMENTS BY REFERENCE

The SEC allows us to “incorporate by reference” into this prospectus certain information that we file with them. Incorporation by reference allows us toit, which means that we can disclose important information to you by referring you to those other documents. The information incorporated by reference is an importantconsidered to be a part of this prospectus, and information that we file later with the SEC will automatically update and supersede this information. Statementsinformation contained in this prospectus regarding the provisions of certain documents filed with, or incorporatedand any accompanying prospectus supplement. We incorporate by reference in, the registration statement are not necessarily complete and each statement is qualified in all respects by that reference. Copies of all or any part of the registration statement, including the documents incorporated by reference or the exhibits, may be obtained upon payment of the prescribed rates at the offices of the SEC listed above in “Where to Find More Information.” Thebelow and all documents we are incorporating by reference are:

The SEC file number for each of the documents listed above is001-37695.

In addition, all documents subsequently filed by us pursuant to Section 13(a), 13(c), 14, or 15(d) of the Securities Exchange Act, prior to the termination of 1934, the offering covered by this prospectus (provided, however, that we are not incorporating, in each case, any documents or information deemed to have been “furnished” and not filed in accordance with SEC rules):

Any statement contained in a document incorporated by reference in this prospectus or in a document incorporated or deemed to be incorporated by reference into thisany prospectus willsupplement shall be deemed to be modified or superseded for purposes of this prospectus to the extent that a statement contained herein, therein or in this prospectus or any other subsequently filed document that also is deemed to be incorporated by reference into this prospectusherein or therein modifies or supersedes thesuch statement. Any statement so modified or superseded willshall not be deemed, except as so modified or superseded, to constitute a part of this prospectus.prospectus or any prospectus supplement.

We will provide without charge to each person, including any beneficial owner, to whom a copy of this prospectus is delivered, upon written or oral request, at no cost to the request of any such person,requester, a copy of any orand all of the information incorporated herein by reference (exclusive of exhibits to such documents unless such exhibits are specifically incorporated by reference herein). Requests, whether written or oral, for such copies should be directed to Proteostasis Therapeutics, Inc., Attention: Investor Relations, 200 Technology Square, 4^th Floor, Cambridge, MA 02139, (617)225-0096.

You should rely only on information contained in, or incorporated by reference into, this prospectus and any prospectus supplement. We have not authorized anyone to provide you with information different from that contained in this prospectus orhas been incorporated by reference in this prospectus. We areprospectus but not making offersdelivered with the prospectus.

Requests for such information should be directed to sellour Corporate Secretary at the securities in any jurisdiction in which such an offer or solicitation is not authorized or in whichaddress below:

Kineta, Inc.

219 Terry Ave. N., Suite 300

Seattle, WA 98109

Attention: Secretary
Telephone: (206) 378-0400

Please include your contact information with the person making such offer or solicitation is not qualifiedrequest.

KINETA, INC.

Up to do so or to anyone to whom it is unlawful to make such offer or solicitation.

PROSPECTUS

, 2023

PART II

INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14. Other Expenses of Issuance and Distribution

The following table sets forth an itemization of the variouscosts and expenses, all of which we will pay,other than underwriting discounts and commissions, payable by the registrant in connection with the issuance and distributionsale of the securities being registered:registered hereby.

* These fees and expenses depend on the securities offered and the number of issuances, and accordingly cannot be estimated at this time and will be reflected in the applicable prospectus supplement.

Item 15. Indemnification of Directors and Officers

Section 145 of the Delaware General Corporation Law of the State of Delaware provides, in general, that(DGCL) authorizes a corporation incorporated under the lawsto indemnify its directors and officers against liabilities arising out of the State of Delaware, as weactions, suits and proceedings to which they are may indemnify any person who wasmade or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding (other than a derivative action by or in the right of the corporation) by reason of the fact that such person isthey have served or was a director, officer, employee or agent of the corporation, or is or wasare currently serving at the request of the corporation as a director or officer employee or agent of another enterprise, againstto a corporation. The indemnity may cover expenses (including attorneys’ fees), judgments, fines, and amounts paid in settlement actually and reasonably incurred by such personthe director or officer in connection with any such action, suit or proceeding if such person acted in good faith and in a manner such person reasonably believedproceeding. Section 145 permits corporations to be in or not opposed to the best interests of the corporation and, with respect to any criminal action or proceeding, had no reasonable cause to believe such person’s conduct was unlawful. In the case of a derivative action, a Delaware corporation may indemnify any such person againstpay expenses (including attorneys’ fees) actually and reasonably incurred by such persondirectors and officers in connection withadvance of the defense or settlementfinal disposition of such action, suit or suit ifproceeding. In addition, Section 145 provides that a corporation has the power to purchase and maintain insurance on behalf of its directors and officers against any liability asserted against them and incurred by them in their capacity as a director or officer, or arising out of their status as such, person acted in good faith and in a manner such person reasonably believed to be inwhether or not opposed to the best interests of the corporation except that no indemnification will be madewould have the power to indemnify the director or officer against such liability under Section 145.

Provisions in respect of any claim, issue or matter as to which such person will have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery of the State of Delaware or any other court in which such action was brought determines such person is fairly and reasonably entitled to indemnity for such expenses.

Ourour certificate of incorporation and bylaws limit or eliminate the personal liability of our directors to the fullest extent permitted by the DGCL, as it now exists or may in the future be amended. Consequently, a director will not be personally liable to us or our stockholders for monetary damages or breach of fiduciary duty as a director, except for liability for:

These limitations of liability do not alter director liability under the federal securities laws and do not affect the availability of equitable remedies, such as an injunction or rescission.

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In addition, our bylaws provide that that:

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The right ofWe have entered into form indemnification herein provided shall be in addition to and not exclusive of any other rights to which any officer or Director, or any such persons who serve at its request as aforesaid, may otherwise be lawfully entitled. As used in this Section, the terms “officer,” and “director,” include their respective heirs, executors, and administrators.

Any underwriting agreements that we may enter into will likely provide for the indemnification of us, our controlling persons,with our directors and certain of our officers. Among other things, and subject to certain limitations, the form indemnification agreements provide for advancement and indemnification, within the bounds of Delaware law, for losses directors and officers bymay incur in connection with or arising out of the underwriters againstperformance of their duties.

We also maintain general liability insurance which covers certain liabilities of our directors and officers arising out of claims based on acts or omissions in their capacities as directors or officers, including liabilities under the Securities ActAct.

The foregoing summaries are necessarily subject to the complete text of 1933, as amended.the referenced sections of the DGCL, the certificate of incorporation, the bylaws, and the form indemnification agreements and are qualified in their entirety by reference thereto.

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The exhibits to this registration statement are listed in the following exhibit index.

Item 16. Exhibits

_____________

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933 the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on FormS-3 and has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Cambridge, CommonwealthSeattle, State of Massachusetts,Washington, on April 6, 2018.November 3, 2023.

We, the undersigned officers

POWER OF ATTORNEY

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below constitutes and directorsappoints Shawn Iadonato and Pauline Kenny, and each or any of Proteostasis Therapeutics, Inc. hereby severally constitute and appoint Meenu Chhabra, ourthem, as their true and lawfulattorney-in-fact attorneys-in-fact and agent,agents, with full power of substitution and resubstitution, for hertheir and in hertheir name, place and stead, and in any and all capacities, to sign any and all amendments (including post-effective amendments) to this registration statement, and to sign any registration statement for the same offering covered by this registration statement filed pursuant to Rule 462(b) under the Securities Act of 1933, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the U.S. Securities and Exchange Commission, granting unto saidattorney-in-fact attorneys-in-fact and agentagents, and each of them, full power and authority to do and perform each and every act and thing requisite orand necessary to be done in and about the premises,connection therewith, as fullfully to all intents and purposes as shethey might or could do in person, hereby ratifying and confirming all that saidattorney-in-fact attorneys-in-fact and agentagents, or her substituteany of them, or their substitutes, may lawfully do or cause to be done by virtue hereof.thereof. This Power of Attorney may be signed in any number of counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument.

Pursuant to the requirements of the Securities Act of 1933 this registration statement on FormS-3has been signed by the following persons in the capacities heldand on the dates indicated.

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