# EDGAR Filing Document

**Accession Number:** 0001599298
**File Stem:** 0001387131-23-003656
**Filing Date:** 2023-3
**Character Count:** 71855
**Document Hash:** 1c1b8779cd2d107481c3375246d2c0d3
**Contains OCR:** False
**Source Format:** 

## Filing Content

## Filing Summary
**0001387131-23-003656.hdr.sgml**: 20230317

**ACCESSION NUMBER**: 0001387131-23-003656

**CONFORMED SUBMISSION TYPE**: S-3

**PUBLIC DOCUMENT COUNT**: 5

**FILED AS OF DATE**: 20230317

**DATE AS OF CHANGE**: 20230317

**FILER**: 

**COMPANY DATA:**
- **COMPANY CONFORMED NAME:** Summit Therapeutics Inc.
- **CENTRAL INDEX KEY:** 0001599298
- **STANDARD INDUSTRIAL CLASSIFICATION:** PHARMACEUTICAL PREPARATIONS [2834]
- **IRS NUMBER:** 000000000
- **STATE OF INCORPORATION:** DE
- **FISCAL YEAR END:** 1231

**FILING VALUES:**
- **FORM TYPE:** S-3
- **SEC ACT:** 1933 Act
- **SEC FILE NUMBER:** 333-270656
- **FILM NUMBER:** 23742979

**BUSINESS ADDRESS:**
- **STREET 1:** 2882 SAND HILL ROAD
- **STREET 2:** SUITE 106
- **CITY:** MENLO PARK
- **STATE:** CA
- **ZIP:** 94025
- **BUSINESS PHONE:** 617-514-7149

**MAIL ADDRESS:**
- **STREET 1:** 2882 SAND HILL ROAD
- **STREET 2:** SUITE 106
- **CITY:** MENLO PARK
- **STATE:** CA
- **ZIP:** 94025

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Summit Therapeutics plc
- **DATE OF NAME CHANGE:** 20150219

**FORMER COMPANY:**
- **FORMER CONFORMED NAME:** Summit Corp plc
- **DATE OF NAME CHANGE:** 20140205

**As filed with the U.S. Securities and Exchange Commission on March 17, 2023**

**Registration Statement No. 333-**

**UNITED STATES**

**SECURITIES AND EXCHANGE COMMISSION**

**WASHINGTON, D.C. 20549**

**FORM S-3**

 **REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933**

**Summit Therapeutics Inc.**

(Exact name of registrant as specified in its charter)

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| | |
|:---|:---|
| **Delaware**  | **37-1979717** |
| (State or other jurisdiction of incorporation or organization) | (I.R.S. Employer Identification Number) |

---

**2882 Sand Hill Road, Suite 106**

**Menlo Park, CA 94025**

**(650) 460-8308**

(Address, including zip code, and telephone number, including area code, of registrant's principal executive offices)

---

| | |
|:---|:---|
| **Robert W. Duggan** | **Mahkam Zanganeh** |
| **Chairman and Chief Executive Officer** | **Co-Chief Executive Officer and President** |
| **Summit Therapeutics Inc.** | **Summit Therapeutics Inc.** |
| **2882 Sand Hill Road, Suite 106** | **2882 Sand Hill Road, Suite 106** |
| **Menlo Park, CA 94025** | **Menlo Park, CA 94025** |
| **(650) 460-8308** | **(650) 460-8308** |

---

(Name, address, including zip code, and telephone number, including area code, of agent for service)

***With copies to:***

**Adam Finerman, Esq.**

**Baker & Hostetler LLP**

**45 Rockefeller Plaza**

**New York, NY 10111**

**Tel: (212) 589-4233**

**Approximate date of commencement of proposed sale to the public:** As soon as practicable after this registration statement becomes effective.

If the only securities being registered on this Form are being offered pursuant to dividend or interest reinvestment plans, please check the following 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 check the following 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, a non-accelerated filer, 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 Rule 12b-2 of the Exchange Act.

Large accelerated filer ☐ Accelerated filer ☐ <br> Non-accelerated filer ☒ Smaller reporting company ☒ <br> Emerging growth company ☐

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. ☐

**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 Section 8(a) of the Securities Act of 1933 or until the Registration Statement shall become effective on such date as the Commission acting pursuant to said Section 8(a), may determine.**

**The information in this prospectus is not complete and may be changed. The selling stockholders 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 we are not soliciting offers to buy these securities in any jurisdiction where the offer or sale is not permitted.**

**PRELIMINARY PROSPECTUS SUBJECT TO COMPLETION, DATED MARCH 17, 2023**

**<u>PROSPECTUS</u>**

**SUMMIT THERAPEUTICS INC.**

 **19,720,291 Shares of Common Stock**

The selling stockholders of Summit Therapeutics Inc. ("Summit, "we", "us", "our," "ours," "our company," "our group" or similar terms refer to Summit Therapeutics Inc., a Delaware corporation, and its consolidated subsidiaries) identified in this prospectus, including their pledgees, donees, transferees, assigns or other successors in interest ("selling stockholders"), may, from time to time, offer and resell under this prospectus up to 19,720,291 shares in the aggregate (the "Shares") of our common stock, par value $0.01 per share (the "Common Stock"). The selling stockholders will receive all of the proceeds from any sales of the Shares offered hereby and we will not receive any proceeds from any such sales. This prospectus describes the general terms of the Shares and the general manner in which the Shares will be offered. You should read this prospectus and any applicable prospectus supplement carefully before you invest in the Shares.

Our registration of the Shares covered by this prospectus does not mean that the selling stockholders will offer or sell any of the Shares. The selling stockholders may sell any, all or none of the securities offered by this prospectus and we do not know when or in what amount the selling stockholders may sell their shares of Common Stock hereunder following the effective date of this registration statement. The timing and amount of any sale are within the sole discretion of the selling stockholders.

The selling stockholders may sell the Shares through public or private transactions at market prices prevailing at the time of sale or at negotiated prices. For further information regarding the possible methods by which the Shares may be distributed, see "*Plan of Distribution*" beginning on page 5 in this prospectus.

Our Common Stock is listed on the Nasdaq Global Market under the symbol "SMMT." On March 16, 2023, the last reported sale price for our Common Stock was $1.83 per share.

**Investing in our securities involves a high degree of risk. See "*Risk Factors*" beginning on page 4 of this prospectus and page 26 of our Annual Report on Form 10-K for the year ended December 31, 2022, incorporated by reference herein as well as the other information contained in this prospectus and the documents incorporated by reference in this prospectus or in any accompanying prospectus supplement for a discussion of the factors you should carefully consider before making a decision to invest in our securities.** 

**You should rely only on the information contained in this prospectus or any prospectus supplement or amendment hereto. We have not authorized anyone to provide you with different information.**

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

The date of this prospectus is March 17, 2023

**<u>**Table of Contents**</u>**

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| | |
|:---|:---|
|  | <u>Page</u> |
| [ABOUT THIS PROSPECTUS](#summts3a001) | 1 |
| [CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS](#summts3a002) | 1 |
| [PROSPECTUS SUMMARY](#summts3a003) | 2 |
| [RISK FACTORS](#summts3a004) | 4 |
| [USE OF PROCEEDS](#summts3a005) | 4 |
| [SELLING STOCKHOLDERS](#summts3a006) | 4 |
| [PLAN OF DISTRIBUTION](#summts3a007) | 5 |
| [LEGAL MATTERS](#summts3a008) | 7 |
| [EXPERTS](#summts3a009) | 7 |
| [INCORPORATION OF CERTAIN INFORMATION BY REFERENCE](#summts3a010) | 7 |
| [WHERE YOU CAN FIND MORE INFORMATION](#summts3a011) | 8 |

---

**ABOUT THIS PROSPECTUS**

This prospectus is part of a registration statement that we filed with the Securities and Exchange Commission (the "SEC") pursuant to which the selling stockholders named herein may, from time to time, offer and sell or otherwise dispose of the Shares covered by this prospectus.

This prospectus provides you with a general description of the securities which may be offered. You should read this prospectus, the documents incorporated by reference into this prospectus, and any prospectus supplement or free writing prospectus that we may authorize for use in connection with this prospectus in their entirety before making an investment decision. You should also read and consider the information in the documents to which we have referred you in the sections of this prospectus entitled "*Incorporation of Certain Information by Reference*" beginning on page 7 and "*Where You Can Find More Information*" beginning on page 8. These documents contain important information that you should consider when making your investment decision.

You should only rely on the information contained in, or incorporated by reference into, this prospectus, in any prospectus supplement or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. We have not authorized anyone to provide any information other than that contained in this prospectus, in any prospectus supplement or in any free writing prospectus prepared by or on behalf of us or to which we have referred you. We are offering to sell, and seeking offers to buy, securities only in jurisdictions where such offers and sales are permitted. The information in this prospectus, in any prospectus supplement or any free writing prospectus is accurate only as of its date, regardless of its time of delivery or of any sale of securities. Our business, financial condition, results of operations and prospects may have changed since that date.

Unless otherwise indicated, information contained in, or incorporated by reference into, this prospectus concerning our industry and the markets in which we operate, including our general expectations and market position, market opportunity and market share, is based on information from our own management estimates and research, as well as from industry and general publications and research, surveys and studies conducted by third parties. Management estimates are derived from publicly available information, our knowledge of our industry and assumptions based on such information and knowledge, which we believe to be reasonable. In addition, assumptions and estimates of our and our industry's future performance are necessarily subject to a high degree of uncertainty and risk due to a variety of factors. These and other factors could cause our future performance to differ materially from our assumptions and estimates. See "*Cautionary Note Regarding Forward-Looking Statements*" beginning on page 1.

Except as otherwise indicated herein or as the context otherwise requires, references in this prospectus to "Summit," the "Company," "we," "us," "our" and similar references refer to Summit Therapeutics Inc., a Delaware corporation, and its consolidated subsidiaries.

**CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS**

Some of the statements made under "*Prospectus Summary*," "*Use of Proceeds*," and elsewhere in this prospectus and the documents incorporated by reference herein, including in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022, constitute forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as "may," "will," "should," "expects," "plans," "anticipates," "believes," "estimates," "predicts," "potential" "intends" or "continue," or the negative of these terms or other comparable terminology.

These forward-looking statements may include, but are not limited to, statements relating to our objectives, plans and strategies, statements that contain projections of results of operations or of financial condition, expected capital needs and expenses, statements relating to the research, development, completion and use of our products, and all statements (other than statements of historical facts) that address activities, events or developments that we intend, expect, project, believe or anticipate will or may occur in the future.

Forward-looking statements are not guarantees of future performance and are subject to risks and uncertainties. We have based these forward-looking statements on assumptions and assessments made by our management in light of their experience and their perception of historical trends, current conditions, expected future developments and other factors they believe to be appropriate.

Important factors that could cause actual results, developments and business decisions to differ materially from those anticipated in these forward-looking statements include, among others, those factors referred to in our Annual Report on Form 10-K for the fiscal year ended December 31, 2022, which is incorporated by reference herein.

These statements are only current predictions and are subject to known and unknown risks, uncertainties, and other factors that may cause our or our industry's actual results, levels of activity, performance or achievements to be materially different from those anticipated by the forward-looking statements. We discuss many of these risks in the documents incorporated by reference herein. You should not rely upon forward-looking statements as predictions of future events.

Although we believe that the expectations reflected in the forward-looking statements are reasonable, we cannot guarantee future results, levels of activity, performance, or achievements. Except as required by law, we are under no duty to update or revise any of the forward-looking statements, whether as a result of new information, future events or otherwise, after the date of this prospectus.

**PROSPECTUS SUMMARY**

*This summary highlights certain information about us and selected information contained in the prospectus. This summary is not complete and does not contain all of the information that may be important to you. For a more complete understanding of the Company, we encourage you to read and consider the more detailed information included or incorporated by reference in this prospectus and our most recent consolidated financial statements and related notes.* 

**Overview**

We are a biopharmaceutical company focused on the discovery, development, and commercialization of patient-, physician-, caregiver- and societal-friendly medicinal therapies intended to improve quality of life, increase potential duration of life, and resolve serious unmet medical needs. Our pipeline of product candidates is designed with the goal to become the patient-friendly, new-era standard-of-care medicines, in the therapeutic area of oncology.

On December 5, 2022, we entered into a Collaboration and License Agreement (the "License Agreement") with Akeso, Inc. and its affiliates ("Akeso") pursuant to which we are partnering with Akeso to in-license its breakthrough bispecific antibody, ivonescimab. Ivonescimab, known as AK112 in China and Australia, and also as SMT112 in the United States, Canada, Europe, and Japan, is a novel, potential first-in-class bispecific antibody intending to combine the effects of immunotherapy via a blockade of PD-1 with the anti-angiogenesis effects of an anti-VEGF into a single molecule. Ivonescimab was engineered to bring two well established oncology targeted mechanisms together. Through the License Agreement, we obtained the rights to develop and commercialize SMT112 in the United States, Canada, Europe, and Japan. The License Agreement and transaction closed on January 17, 2023 following customary waiting periods.

The entry into the License Agreement represents a significant change in the Company's strategy. All prior development and marketing activities relating to ridinilazole are being terminated. All business activities related to anti-infectives are being reviewed for partnership opportunities for potential further development. Our future operations will be focused on the development of ivonescimab and other future activities as the Company determines.

On September 28, 2022, we determined that we would seek partners or a divestiture of ridinilazole, our lead product candidate for treating patients suffering from *Clostridioides difficile* infection, also known as *C. difficile* infection, or CDI, as the path forward for the clinical development of the asset. As a result of this determination, we discontinued our only active study for ridinilazole, a pediatric clinical trial evaluating ridinilazole for treating adolescent patients with CDI. We are currently involved in activities related to closeout of ridinilazole clinical trials.

Our other product candidate, SMT-738, has been in development for combating multidrug resistant infections, specifically carbapenem-resistant Enterobacteriaceae infections. SMT-738 is the first of a novel class of precision antibiotics that has been in preclinical development and has been undergoing investigational new drug enabling activities. We will continue to pursue partnerships for further development of SMT-738.

We have devoted substantially all of our efforts to research and development, including clinical trials. We have not completed the development of any drugs. We expect to continue to incur significant expenses and increasing operating losses for at least the next few years. The net losses we incur may fluctuate significantly from quarter to quarter and year to year, due to the nature and timing of our research and development activities. We expect that our research and development and general and administrative expenses will continue to be significant in connection with our ongoing research and development efforts.

As a result, we will need to seek additional funding in the future to fund operations. Until such time, if ever, as we can generate substantial product revenues, we expect to finance our cash needs through a combination of some, or all, of the following: equity and debt offerings, collaborations, strategic alliances, grants and clinical trial support from government entities, philanthropic, non-government and not-for-profit organizations, and marketing, distribution or licensing arrangements. We may be unable to raise sufficient funds through equity or debt financings, or other arrangements when needed based on our liquidity needs on acceptable terms, or at all.

**Our Strategy**

Our goal is to become a fully integrated biopharmaceutical company focused on the discovery, development, and commercialization of our pipeline product portfolio in the therapeutic area of oncology.

**Corporate Information**

Summit Therapeutics Inc. was incorporated in Delaware on July 17, 2020. Our principal executive office is located at 2882 Sand Hill Road, Suite 106, Menlo Park, California and our phone number is (650) 460-8308. Our website is https://www.smmttx.com. Information contained on or accessible through our website is not incorporated by reference into this prospectus and should not be considered a part of this prospectus.

**Recent Developments**

On March 1, 2023, the Company closed on its previously announced $500,000,000 rights offering (the "February Rights Offering"), which was fully subscribed. The Company received aggregate gross proceeds from the February Rights Offering of $500,000,000 from the sale of 476,190,471 shares of our common stock at a price per share of $1.05. Issuance costs associated with the February Rights Offering were approximately $500,000.

**The Offering**

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| | |
|:---|:---|
| *Issuer:* | &nbsp;&nbsp;Summit Therapeutics Inc. |
| *Shares of Common Stock Offered for Resale by the Selling Stockholders:* | &nbsp;&nbsp;Up to an aggregate of 19,720,291 shares |
| *Use of Proceeds:* | &nbsp;&nbsp;The selling stockholders will receive all of the net proceeds from the sale of the Shares. We will not receive any proceeds from the sale of the Shares. |
| *Offering Price:* | &nbsp;&nbsp; The selling stockholders may sell all or a portion of their Shares through public or private transactions at prevailing market prices or at privately negotiated prices. |
| *Market for our Common Stock:* | &nbsp;&nbsp; Our Common Stock is listed on the Nasdaq Global Market. |
| *Nasdaq Ticker Symbol:* | &nbsp;&nbsp; SMMT |

---

**RISK FACTORS**

Investing in our Common Stock involves risks. Please carefully consider the risk factors described in our periodic reports filed with the SEC, including those set forth under the caption "Item 1A. Risk Factors" in our most recently filed annual report on Form 10-K for the fiscal year ended December 31, 2022, which is incorporated by reference in this prospectus, and in any other documents we may file in the future and that will be incorporated by reference into this prospectus. You should carefully consider these risks as well as other information we include or incorporate by reference in this prospectus.

**USE OF PROCEEDS**

All of the Shares offered and sold by the selling stockholders pursuant to this prospectus will be sold by the selling stockholders for their respective accounts. We will not receive any of the proceeds from these sales.

**SELLING STOCKHOLDERS**

This prospectus covers the resale from time to time of up to an aggregate of 19,720,291 shares of our Common Stock by the selling stockholders.

The selling stockholders identified in the table below may from time to time offer and sell under this prospectus any or all of the Shares described under the column "*Number of Shares of Common Stock Being Offered*" in the table below. The table below has been prepared based upon information furnished to us by the selling stockholders as of the dates represented in the footnotes accompanying the table. The selling stockholders identified below may have sold, transferred or otherwise disposed of some or all of their shares since the date on which the information in the following table is presented in transactions exempt from or not subject to the registration requirements of the Securities Act. Information concerning the selling stockholders may change from time to time and, if necessary, we will amend or supplement this prospectus accordingly and as required.

The following table and footnote disclosure following the table sets forth the name of each selling stockholder, the nature of any position, office or other material relationship, if any, that the selling stockholders have had within the past three years with us or with any of our predecessors or affiliates, and the number of shares of our Common Stock beneficially owned by the selling stockholders before this offering. The number of shares reflected are those beneficially owned, as determined under applicable rules of the SEC, and the information is not necessarily indicative of beneficial ownership for any other purpose. Under applicable SEC rules, beneficial ownership includes any shares of Common Stock as to which a person has sole or shared voting power or investment power and any shares of Common Stock which the person has the right to acquire within 60 days after March 13, 2023 through the exercise of any option, warrant or right or through the conversion of any convertible security. Unless otherwise indicated in the footnotes to the table below and subject to community property laws where applicable, we believe, based on information furnished to us that each of the selling stockholders named in this table has sole voting and investment power with respect to the shares indicated as beneficially owned.

We have assumed that all shares of Common Stock reflected in the table as being offered in the offering covered by this prospectus will be sold from time to time in this offering. We cannot provide an estimate as to the number of shares of Common Stock that will be held by the selling stockholders upon termination of the offering covered by this prospectus because the selling stockholders may offer some, all or none of their shares of Common Stock being offered in the offering. Information about the selling stockholders may change over time. Any changed information will be set forth in an amendment to the resale registration statement or supplement to this prospectus, to the extent required by law.

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| | | | | | |
|:---|:---|:---|:---|:---|:---|
|  | **Shares of Common Stock <br> Beneficially Owned Prior to <br> this Offering<br>**  | **Shares of Common Stock <br> Beneficially Owned Prior to <br> this Offering<br>**  | **Number of <br> Shares of <br> Common Stock** | **Shares of Common Stock to be <br> Beneficially Owned Upon <br> Completion of this Offering<br>**  | **Shares of Common Stock to be <br> Beneficially Owned Upon <br> Completion of this Offering<br>**  |
| **Selling Stockholder<sup>(1)</sup>** | **Number** | **Percentage<sup>(2)</sup>** | **Being Offered** | **Number** | **Percentage<sup>(2)(6)</sup>** |
| Akeso, Inc.<sup>(3)</sup> | 31523530 | 4.52% | 10000000 | 21523530 | 3.08% |
| Robert W. Duggan<sup>(4)</sup> | 552354161 | 78.72% | 9346434 | 543007727 | 77.39% |
| Mahkam Zanganeh<sup>(5)</sup> | 36882393 | 5.27% | 373857 | 36508536 | 5.21% |

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<sup>(1)</sup> All information regarding selling stockholders is based on information provided to the Company as of March 13, 2023.<br> <sup>(2)</sup> Percentage ownership is based on a denominator equal to the sum of (i) 697,685,365 shares of our Common Stock outstanding as of March 13, 2023 and (ii) the number of shares of Common Stock issuable upon exercise or conversion of convertible securities beneficially owned by the applicable selling stockholder.

<sup>(3)</sup> This Registration Statement is registering the resale of 10,000,000 shares of Common Stock acquired in connection with the first upfront payment pursuant to the License Agreement on January 17, 2023.

<sup>(4)</sup> This information is based on a Schedule 13D/A filed on February 16, 2023 by Robert W. Duggan, our Chief Executive Officer and Chairman of the Board, as updated by the Form 4 filed by Mr. Duggan on March 8, 2023, which includes warrants to purchase up to 3,985,055 shares of Common Stock. This Registration Statement is registering the resale of 9,346,434 shares of Common Stock issued to Mr. Duggan as payment of prepaid interest in connection with that certain Note Purchase Agreement, between Mr. Duggan and the Company.

<sup>(5)</sup> This information is based on a Schedule 13D/A filed on March 13, 2023 by Dr. Mahkam Zanganeh, our co-Chief Executive Officer, President, and member of the Board, which includes 34,457,893 shares of Common Stock collectively owned by the Mahkam Zanganeh Revocable Trust (the "MZ Trust") and the Shaun Zanganeh Irrevocable Trust (the "SZ Trust"), warrants to purchase up to 1,121,177 shares of Common Stock collectively owned by Dr. Zanganeh, the MZ Trust and the SZ Trust, and options to purchase up to 1,303,323 shares of Common Stock owned by Dr. Zanganeh. This Registration Statement is registering the resale of 373,857 shares of Common Stock by the MZ Trust, which were issued to the MZ Trust as payment of prepaid interest in connection with that certain Note Purchase Agreement between Dr. Zanganeh and the Company. By virtue of Dr. Zanganeh's position as the sole trustee of the MZ Trust and the SZ Trust, she may be deemed to beneficially own the shares owned by each such trust.

<sup>(6)</sup> Assumes that all shares of Common Stock being registered for resale under the registration statement of which this prospectus forms a part are sold in this offering, and that none of the selling stockholders dispose of any additional shares of our Common Stock after the date of this prospectus and prior to completion of this offering.

**PLAN OF DISTRIBUTION**

We are registering the Shares to permit the resale of the Shares by the selling stockholders from time to time after the date of this prospectus. We will not receive any of the proceeds from the sale by the selling stockholders of the Shares. We will bear all fees and expenses incident to the registration of the Shares including, without limitation, SEC filing fees and expenses of compliance with state securities or "blue sky" laws; *provided*, *however*, that each selling stockholder will pay all underwriting discounts and selling commissions or fees incident to sales of the Shares, if any, and any related legal expenses incurred by such selling stockholder.

The selling stockholders, which, as used herein, includes donees, pledgees, transferees or other successors-in-interest selling Common Stock or interests in Common Stock received after the date of this prospectus from a selling stockholder as a gift, pledge, partnership distribution or other transfer, may, from time to time, sell, transfer or otherwise dispose of any or all of their Shares or interests in Shares on any stock exchange, market or trading facility on which the Common Stock is traded or in private transactions. These dispositions may be at fixed prices, at prevailing market prices at the time of sale, at prices related to the prevailing market price, at varying prices determined at the time of sale, or at negotiated prices.

The selling stockholders may use any one or more of the following methods when disposing of Shares or interests therein:

● ordinary brokerage transactions and transactions in which the broker-dealer solicits purchasers;

● block trades in which the broker-dealer will attempt to sell shares as agent, but may position and resell a portion of the block as principal to facilitate the transaction;

● purchases by a broker-dealer as principal and resale by the broker-dealer for its account;

● an exchange distribution in accordance with the rules of the applicable exchange;

● privately negotiated transactions;

● short sales effected after the date the registration statement of which this prospectus is a part is declared effective by the SEC;

● through the writing or settlement of options or other hedging transactions, whether through an options exchange or otherwise;

● broker-dealers may agree with the selling holders to sell a specified number of such Shares at a stipulated price per share;

● a combination of any such methods of sale;

● privately negotiated transactions; and

● any other method permitted by applicable law.

The selling stockholders may, from time to time, pledge or grant a security interest in some or all of the Shares owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell the Shares, from time to time, under this prospectus, or under an amendment to this prospectus under Rule 424(b)(3) or other applicable provision of the Securities Act amending the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under this prospectus. The selling stockholders also may transfer the shares of Common Stock in other circumstances, in which case the transferees, pledgees or other successors in interest will be the selling beneficial owners for purposes of this prospectus.

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

The aggregate proceeds to the selling stockholders from the sale of the Shares offered by them will be the purchase price of the shares less discounts or commissions, if any. Each of the selling stockholders reserves the right to accept and, together with their agents from time to time, to reject, in whole or in part, any proposed purchase of Shares to be made directly or through agents. We will not receive any of the proceeds from this offering.

The selling stockholders also may resell all or a portion of the shares of Common Stock in open market transactions in reliance upon Rule 144 under the Securities Act of 1933, provided that they meet the criteria and conform to the requirements of that rule.

The selling stockholders and any underwriters, broker-dealers or agents that participate in the sale of the shares of Common Stock or interests therein may be "underwriters" within the meaning of Section 2(11) of the Securities Act. Any discounts, commissions, concessions or profit they earn on any resale of the shares of Common Stock may be underwriting discounts and commissions under the Securities Act. Selling stockholders who are "underwriters" within the meaning of Section 2(11) of the Securities Act will be subject to the prospectus delivery requirements of the Securities Act.

To the extent required, the Shares to be sold, the names of the selling stockholders, the respective purchase prices and public offering prices, the names of any agents, dealer or underwriter, any applicable commissions or discounts with respect to a particular offer will be set forth in an accompanying prospectus supplement or, if appropriate, a post-effective amendment to the registration statement that includes this prospectus.

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

We have advised the selling stockholders that the anti-manipulation rules of Regulation M under the Exchange Act may apply to sales of shares of Common Stock in the market and to the activities of the selling stockholders and their affiliates. In addition, to the extent applicable we will make copies of this prospectus (as it may be supplemented or amended from time to time) available to the selling stockholders for the purpose of satisfying the prospectus delivery requirements of the Securities Act. The selling stockholders may indemnify any broker-dealer that participates in transactions involving the sale of the shares of Common Stock against certain liabilities, including liabilities arising under the Securities Act.

We have agreed to indemnify the selling stockholders against liabilities, including liabilities under the Securities Act and state securities laws, relating to the registration of the shares of Common Stock offered by this prospectus.

**LEGAL MATTERS**

Baker & Hostetler, LLP will pass upon the validity of any securities we offer by this prospectus.

**EXPERTS**

The financial statements incorporated in this prospectus by reference to the Annual Report on Form 10-K for the year ended December 31, 2022 have been so incorporated in reliance on the report (which contains an emphasis of matter paragraph related to a note payable with a principal amount of $100 million maturing in September 2024 as described in Note 17 to the consolidated financial statements and management's evaluation of the events and conditions related to future funding as described in Note 3 to the consolidated financial statements) of PricewaterhouseCoopers LLP, an independent registered public accounting firm, given on the authority of said firm as experts in auditing and accounting.

**INCORPORATION OF CERTAIN INFORMATION BY REFERENCE**

The SEC allows us to "incorporate by reference" information into this prospectus. This means that we can disclose important information about us and our financial condition to you by referring you to other documents filed separately with the SEC. The information incorporated by reference is considered to be a part of this prospectus, except any information that is superseded by information that is included in a document subsequently filed with the SEC.

This prospectus incorporates by reference the documents listed below that we have previously filed with the SEC and any future filings we make with the SEC under Sections 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the "Exchange Act"), from the date of this prospectus until the termination of an offering of securities, except that we are not incorporating by reference any information furnished (and not filed) with the SEC, including any information furnished pursuant to Items 2.02 or 7.01 of Form 8-K or related exhibits furnished pursuant to Item 9.01 of Form 8-K:

● Our Annual Report on Form 10-K for the fiscal year ended December 31, 2022, as filed on March 9, 2023;

● Our Current Reports on Form 8-K filed on [January 9, 2023](http://www.sec.gov/Archives/edgar/data/0001599298/000159929823000009/smmt-20230106.htm) (except for information contained therein which is furnished rather than filed), [January 20, 2023](http://www.sec.gov/Archives/edgar/data/1599298/000159929823000012/smmt-20230116.htm) , [January 27, 2023](http://www.sec.gov/Archives/edgar/data/1599298/000159929823000015/smmt-20230127.htm) , [January 30, 2023](http://www.sec.gov/Archives/edgar/data/1599298/000159929823000020/smmt-20230130.htm) , [February 23, 2023](http://www.sec.gov/Archives/edgar/data/1599298/000159929823000023/smmt-20230223.htm) , and [March 3, 2023](http://www.sec.gov/Archives/edgar/data/1599298/000159929823000026/smmt-20230301.htm) .

● The description of the securities contained in our Current Report on Form 8-K dated [September 18, 2020](http://www.sec.gov/Archives/edgar/data/1599298/000119312520248702/d76627d8k12b.htm) , including any amendment or report filed for the purpose of updating such description.

Any statement contained in a document all or a portion of which is incorporated or deemed to be incorporated by reference herein will be deemed to be modified or superseded to the extent that a statement contained herein or in any other subsequently filed document which also is or is deemed to be incorporated by reference herein modifies or supersedes such statement. Any statement so modified will not be deemed to constitute a part hereof, except as so modified, and any statement so superseded will not be deemed to constitute a part hereof.

A copy of any document incorporated by reference in this prospectus may be obtained at no cost by writing or telephoning us at the following address and telephone number:

Summit Therapeutics Inc.

2882 Sand Hill Road, Suite 106

Menlo Park, CA 94025

Attention: Investor Relations

(650) 460-8308

We maintain a website at www.smmttx.com. Information about us, including our reports filed with the SEC, is available through that site. Such reports are accessible at no charge through our website and are made available as soon as reasonably practicable after such material is filed with or furnished to the SEC. Our website and the information contained on that website, or connected to that website, are not incorporated by reference in this prospectus.

You may read and copy any materials we file with the SEC at the SEC's website mentioned under the heading "*Where You Can Find More Information*." The information on the SEC's website is not incorporated by reference in this prospectus.

**WHERE YOU CAN FIND MORE INFORMATION**

We file annual, quarterly and current reports, proxy statements and other information with the SEC. Our SEC filings are available to the public over the Internet at the SEC's website at www.sec.gov. Copies of certain information filed by us with the SEC are also available on our website at www.smmttx.com. The information contained in, or accessible through, our website, however, should not be considered a part of this prospectus.

This prospectus is part of a registration statement we filed with the SEC. This prospectus does not contain all of the information included in the registration statement and the amendments, exhibits and schedules thereto, in accordance with SEC rules and regulations. You should review the information and exhibits in the registration statement for further information on us and our consolidated subsidiaries and the securities we are offering. Statements in this prospectus concerning any document we filed as an exhibit to the registration statement or that we otherwise filed with the SEC are not intended to be comprehensive and are qualified by reference to these filings. You should review the complete document to evaluate these statements. You can obtain a copy of the registration statement from the SEC at the address listed above or from the SEC's website.

**SUMMIT THERAPEUTICS INC.**

**19,720,291 Shares of Common Stock**

**PROSPECTUS**

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;**[ ], 2023**

**PART II — INFORMATION NOT REQUIRED IN THE PROSPECTUS**

**Item 14. Other Expenses of Issuance and Distribution.**

The following table sets forth all expenses, payable by the registrant in connection with the sale of its Common Stock being registered. All the amounts shown are estimates except the SEC registration fee.

---

| | |
|:---|:---|
|  | **Amount to be Paid** |
| &nbsp;&nbsp;**SEC Registration Fee** | $3086 |
| &nbsp;&nbsp;**Printing Expenses** | $5000 |
| &nbsp;&nbsp;**Accounting Fees and Expenses** | $15000 |
| &nbsp;&nbsp;**Legal Fees and Expenses** | $20000 |
| &nbsp;&nbsp;**Miscellaneous** | $10000 |
| &nbsp;&nbsp;**Total** | $53086 |

---

**Item 15. Indemnification of Directors and Officers.**

Section 145(a) of the Delaware General Corporation Law ("DGCL") provides, in general, that a corporation may indemnify any person who was or is a party to or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the corporation), because he or she is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by the person in connection with such action, suit or proceeding, if he or she acted in good faith and in a manner he or she reasonably believed 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 his or her conduct was unlawful.

Section 145(b) of the DGCL provides, in general, that a corporation may indemnify any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action or suit by or in the right of the corporation to procure a judgment in its favor because the person is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees) actually and reasonably incurred by the person in connection with the defense or settlement of such action or suit if he or she acted in good faith and in a manner he or she reasonably believed to be in or not opposed to the best interests of the corporation, except that no indemnification shall be made with respect to any claim, issue or matter as to which he or she shall have been adjudged to be liable to the corporation unless and only to the extent that the Court of Chancery or other adjudicating court determines that, despite the adjudication of liability but in view of all of the circumstances of the case, he or she is fairly and reasonably entitled to indemnity for such expenses that the Court of Chancery or other adjudicating court shall deem proper.

Section 145(g) of the DGCL provides, in general, that a corporation may purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the corporation, or is or was serving at the request of the corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against any liability asserted against such person and incurred by such person in any such capacity, or arising out of his or her status as such, whether or not the corporation would have the power to indemnify the person against such liability under Section 145 of the DGCL.

The registrant's Certificate of Incorporation provides that the registrant will indemnify each person who was or is a party or threatened to be made a party to or is involved in any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (other than an action by or in the right of the registrant) by reason of the fact that he or she is or was a director or officer of the registrant, or is or was serving at the registrant's request as a director or officer of another corporation, partnership, joint venture, trust or other enterprise to the fullest extent permitted by the DGCL. The registrant's Certificate of Incorporation provides that any reasonable, documented, out-pocket expenses must be advanced to these indemnitees under certain circumstances.

The indemnification provisions contained in the registrant's Certificate of Incorporation are not exclusive. In addition, the registrant has entered into indemnification agreements with each of its directors and executive officers. Each indemnification agreement provides that the registrant will indemnify the director or executive officer to the fullest extent permitted by law for claims arising in his or her capacity as a director or executive officer, provided that he or she acted in good faith and in a manner that he or she reasonably believed to be in, or not opposed to, the registrant's best interests and, with respect to any criminal proceeding, had no reasonable cause to believe that his or her conduct was unlawful. In the event that the registrant does not assume the defense of a claim against a director or executive officer, the registrant is required to advance his or her expenses in connection with his defense, provided that he or she undertakes to repay all amounts advanced if it is ultimately determined that he or she is not entitled to be indemnified by the registrant.

In addition, the registrant maintains standard policies of insurance under which coverage is provided to the registrant's directors and officers against losses arising from claims made by reason of breach of duty or other wrongful act, and to the registrant with respect to payments which may be made by the registrant to such directors and officers pursuant to the above indemnification provisions or otherwise as a matter of law.

**Item 16. Exhibits.**

---

| | |
|:---|:---|
| **Exhibit**<br>**No.** | <br>**Description** |
| 3.1 | [Restated Certificate of Incorporation of the Registrant (incorporated by reference to Exhibit 3.1 to the Registrant's Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on September 18, 2020)](http://www.sec.gov/Archives/edgar/data/1599298/000119312520248702/d76627dex31.htm) |
| 3.2 | [Amendment to Restated Certificate of Incorporation of the Registrant (incorporated by reference to Exhibit 3.1 to the Registrant's Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on July 29, 2022](http://www.sec.gov/Archives/edgar/data/1599298/000159929822000086/summittherapeuticsinc-de.htm)) |
| 3.3 | [Amended and Restated Bylaws (incorporated by reference to Exhibit 3.2 to the Registrant's Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on September 18, 2020)](http://www.sec.gov/Archives/edgar/data/1599298/000119312520248702/d76627dex32.htm) |
| 3.4 | [Amendment No. 2 to Restated Certificate of Incorporation of the Registrant (incorporated by reference to Exhibit 3.1 to the Registrant's Current Report on Form 8-K (File No. 001-36866), filed with the Securities and Exchange Commission on January 20, 2023)](http://www.sec.gov/Archives/edgar/data/0001599298/000159929823000012/smmt-20230116.htm) |
| 5.1\* | [Opinion of Baker & Hostetler LLP](ex5-1.htm) |
| 23.1\* | [Consent of PricewaterhouseCoopers LLP, an independent registered public accounting firm for the Registrant.](ex23-1.htm) |
| 23.3\* | Consent of Baker & Hostetler LLP (included in Exhibit 5.1 hereto) |
| 24.1\* | Powers of Attorney (included on signature page hereto) |
| 107\* | [Filing fee table](ex107.htm) |
| \* | Filed herewith. |

---

**Item 17. Undertakings.**

The undersigned registrant hereby undertakes:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1) To file, during any period in which offers or sales are being made, a post-effective amendment to this registration statement:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) to include any prospectus required by Section 10(a)(3) of the Securities Act;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) to reflect in the prospectus any facts or events arising after the effective date of the registration statement (or the most recent post-effective amendment thereof) which, individually or in the aggregate, represent a fundamental change in the information set forth in the registration statement. Notwithstanding the foregoing, any increase or decrease in volume of securities offered (if the total dollar value of securities offered would not exceed that which was registered) and any deviation from the low or high end of the estimated maximum offering range may be reflected in the form of prospectus filed with the SEC pursuant to Rule 424(b) if, in the aggregate, the changes in volume and price represent no more than 20 percent change in the maximum aggregate offering price set forth in the "Calculation of Registration Fee" table in the effective registration statement; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) to include any material information with respect to the plan of distribution not previously disclosed in the registration statement or any material change to such information in the registration statement;

provided, however, that: Paragraphs (a)(1)(i), (a)(1)(ii) and (a)(1)(iii) of this section do not apply if the information required to be included in a post-effective amendment by those paragraphs is contained in reports filed with or furnished to the SEC by the registrant pursuant to Section 13 or Section 15(d) of the Exchange Act, that are incorporated by reference in the registration statement, or is contained in a form of prospectus filed pursuant to Rule 424(b) that is part of the registration statement.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(2) That, for the purpose of determining any liability under the Securities Act, each such post-effective amendment shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(3) To remove from registration by means of a post-effective amendment any of the securities being registered which remain unsold at the termination of the offering.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(4) That, for the purpose of determining liability under the Securities Act to any purchaser:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) Each prospectus filed by the registrant pursuant to Rule 424(b)(3) shall be deemed to be part of the registration statement as of the date the filed prospectus was deemed part of and included in the registration statement; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) Each prospectus required to be filed pursuant to Rule 424(b)(2), (b)(5) or (b)(7) as part of a registration statement in reliance on Rule 430B relating to an offering made pursuant to Rule 415(a)(1)(i), (vii) or (x) for the purpose of providing the information required by Section 10(a) of the Securities Act shall be deemed to be part of and included in the registration statement as of the earlier of the date such form of prospectus is first used after effectiveness or the date of the first contract of sale of securities in the offering described in the prospectus. As provided in Rule 430B, for liability purposes of the issuer and any person that is at that date an underwriter, such date shall be deemed to be a new effective date of the registration statement relating to the securities in the registration statement to which that prospectus relates, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof. Provided, however, that no statement made in a registration statement or prospectus that is part of the registration statement or made in a document incorporated or deemed incorporated by reference into the registration statement or prospectus that is part of the registration statement will, as to a purchaser with a time of contract of sale prior to such effective date, supersede or modify any statement that was made in the registration statement or prospectus that was part of the registration statement or made in any such document immediately prior to such effective date.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(5) That, for the purpose of determining liability of the registrant under the Securities Act to any purchaser in the initial distribution of the securities, the undersigned registrant undertakes that in a primary offering of securities of the undersigned registrant pursuant to this registration statement, regardless of the underwriting method used to sell the securities to the purchaser, if the securities are offered or sold to such purchaser by means of any of the following communications, the undersigned registrant will be a seller to the purchaser and will be considered to offer or sell such securities to such purchaser:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) Any preliminary prospectus or prospectus of the undersigned registrant relating to the offering required to be filed pursuant to Rule 424;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) Any free writing prospectus relating to the offering prepared by or on behalf of the undersigned registrant or used or referred to by the undersigned registrant;

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iii) The portion of any other free writing prospectus relating to the offering containing material information about the undersigned registrant or its securities provided by or on behalf of the undersigned registrant; and

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(iv) Any other communication that is an offer in the offering made by the undersigned registrant to the purchaser.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(6) That, for purposes of determining any liability under the Securities Act of 1933, each filing of the registrant's annual report pursuant to Section 13(a) or Section 15(d) of the Securities Exchange Act of 1934 (and, where applicable, each filing of an employee benefit plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of 1934) that is incorporated by reference in the registration statement shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(7) Insofar as indemnification for liabilities arising under the Securities Act of 1933 may be permitted to directors, officers and controlling persons of the registrant pursuant to the foregoing provisions, or otherwise, the registrant has been advised that in the opinion of the Securities and Exchange Commission such indemnification is against public policy as expressed in the Securities Act of 1933 and is, therefore, unenforceable. In the event that a claim for indemnification against such liabilities (other than the payment by the registrant of expenses incurred or paid by a director, officer or controlling person of the registrant in the successful defense of any action, suit or proceeding) is asserted by such director, officer or controlling person in connection with the securities being registered, the registrant will, unless in the opinion of its counsel the matter has been settled by controlling precedent, submit to a court of appropriate jurisdiction the question whether such indemnification by it is against public policy as expressed in the Securities Act of 1933 and will be governed by the final adjudication of such issue.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(8) That, for the purposes of determining any liability under the Securities Act of 1933:

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(i) The information omitted from the form of prospectus filed as part of this registration statement in reliance upon Rule 430A and contained in a form of prospectus filed by the registrant pursuant to Rule 424(b)(1) or (4) or 497(h) under the Securities Act shall be deemed to be part of this registration statement as of the time it was declared effective.

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(ii) Each post-effective amendment that contains a form of prospectus shall be deemed to be a new registration statement relating to the securities offered therein, and the offering of such securities at that time shall be deemed to be the initial bona fide offering thereof.

**SIGNATURES**

Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Menlo Park, State of California, on March 17, 2023.

---

| | |
|:---|:---|
| **SUMMIT THERAPEUTICS INC.** | **SUMMIT THERAPEUTICS INC.** |
| By: | /s/ Robert W. Duggan |
|  | Name: Robert W. Duggan |
|  | Title: Chief Executive Officer and Executive Chairman; Principal Executive Officer |

---

---

| | |
|:---|:---|
| By: | /s/ Dr. Mahkam Zanganeh |
|  | Name: Dr. Mahkam Zanganeh |
|  | Title: Co-Chief Executive Officer; President and member of the Board; Principal Executive Officer |

---

**POWER OF ATTORNEY AND SIGNATURES**

KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Robert W. Duggan and Ankur Dhingra, and each of them singly, as the undersigned's true and lawful attorneys-in-fact and agents, with full power of substitution, for the undersigned in any and all capacities, to sign any or all amendments to this Registration Statement (including post-effective amendments), and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully for all intents and purposes as the undersigned might or could do in person, hereby and about the premises hereby ratifying and confirming all that said attorneys-in-fact and agent, proxy and agent, or their substitute, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, as amended, the following persons in the capacities and on the dates indicated have signed this Registration Statement below.

---

| | | |
|:---|:---|:---|
| **Signature** | **Title** | **Date** |
| /s/ Robert W. Duggan | Chief Executive Officer; Executive Chairman (*Principal Executive Officer*) | March 17, 2023 |
| Robert W. Duggan | Chief Executive Officer; Executive Chairman (*Principal Executive Officer*) | March 17, 2023 |
| /s/ Dr. Mahkam Zanganeh | Co-Chief Executive Officer and President, Director (*Principal Executive Officer*) | March 17, 2023 |
| Dr. Mahkam Zanganeh | Co-Chief Executive Officer and President, Director (*Principal Executive Officer*) | March 17, 2023 |
| /s/ Ankur Dhingra | Chief Financial Officer (*Principal Financial and Accounting Officer*) | March 17, 2023 |
| Ankur Dhingra | Chief Financial Officer (*Principal Financial and Accounting Officer*) | March 17, 2023 |
| /s/ Kenneth A. Clark | Director | March 17, 2023 |
| Kenneth A. Clark |  |  |

---

---

| | | |
|:---|:---|:---|
| /s/ Dr. Robert Booth | Director | March 17, 2023 |
| Dr. Robert Booth |  |  |
| /s/ Ujwala Mahatme | Director | March 17, 2023 |
| Ujwala Mahatme |  |  |
| /s/ Manmeet S. Soni | Director | March 17, 2023 |
| Manmeet S. Soni |  |  |
| /s/ Dr. Alessandra Cesano | Director | March 17, 2023 |
| Dr. Alessandra Cesano |  |  |
| /s/ Dr. Yu Xia | Director | March 17, 2023 |
| Dr. Yu Xia |  |  |

---

## Exhibit 5.1

[Summit Therapeutics Inc. S-3](summt-s3_031723.htm)

**Exhibit 5.1**

![](ex51001.jpg)

---

| |
|:---|
| **Baker & Hostetler llp** |
| 45 Rockefeller Plaza |
| New York, NY 10111 |
| T 212.589.4200 |
| F 212.589.4201 |
| www.bakerlaw.com |

---

March 17, 2023

Summit Therapeutics Inc.<br> 2882 Sand Hill Road, Suite 106<br> Menlo Park, California 94025

Ladies and Gentlemen:

We have acted as counsel to Summit Therapeutics Inc., a Delaware corporation (the "Company"), in connection with the filing by the Company with the Securities and Exchange Commission (the "Commission") of a Registration Statement on Form S-3, as may be amended from time to time (the "Registration Statement"), under the Securities Act of 1933, as amended (the "Act"), relating to the registration for resale of 19,720,291 shares in the aggregate (the "Shares") of the Company's common stock, par value $0.01 per share, held by the selling stockholders named in the Registration Statement.

We have examined the Registration Statement, together with the documents incorporated by reference therein, including the related prospectus forming a part thereof (the "Prospectus"). In addition, we have examined originals or copies, certified or otherwise identified to our satisfaction, of such other instruments, documents, certificates and records which we have deemed relevant and necessary for the basis of our opinions hereinafter expressed. In such examination, we have assumed: (i) the authenticity of original documents and the genuineness of all signatures; (ii) the conformity to the originals of all documents submitted to us as copies; (iii) the truth, accuracy and completeness of the information, representations and warranties contained in the instruments, documents, certificates and records we have reviewed; (iv) that the Registration Statement, and any amendments thereto (including post-effective amendments), will have become effective under the Act; and (v) the legal capacity of all natural persons. As to any facts material to the opinions expressed herein that were not independently established or verified, we have relied upon oral or written statements and representations of officers and other representatives of the Company.

We express no opinion herein as to the laws of any state or jurisdiction other than the General Corporation Law of the State of Delaware (including the statutory provisions and all applicable judicial decisions interpreting those laws) and the federal laws of the United States of America.

*Atlanta Chicago Cincinnati Cleveland Columbus Costa Mesa Dallas Denver Houston*

*Los Angeles New York Orlando Philadelphia San Francisco Seattle Washington, DC Wilmington* 

March 17, 2023

We express no opinion as to (i) the effect of any bankruptcy, insolvency, reorganization, arrangement, fraudulent conveyance, moratorium or other similar laws relating to or affecting the rights of creditors generally, (ii) rights to indemnification and contribution which may be limited by applicable law or equitable principles, or (iii) the effect of general principles of equity, including, without limitation, concepts of materiality, reasonableness, good faith and fair dealing, the effect of judicial discretion and the possible unavailability of specific performance, injunctive relief or other equitable relief, and the limitations on rights of acceleration, whether considered in a proceeding in equity or at law.

On the basis of the foregoing, we are of the opinion that the Shares are validly issued, fully paid and non-assessable.

We hereby consent to the filing of this opinion as Exhibit 5.1 to the Registration Statement and to the reference to our firm under the caption "Legal Matters" in the Prospectus. In giving such consent, we do not thereby admit that we are included in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Commission promulgated thereunder. We assume no obligation to update or supplement any of the opinion set forth herein to reflect any changes of law or fact that may occur following the date hereof.

---

| |
|:---|
| Very truly yours, |
| /s/ Baker & Hostetler LLP |
| BAKER & HOSTETLER LLP |

---

## Exhibit 23.1

[Summit Therapeutics Inc. S-3](summt-s3_031723.htm)

**Exhibit 23.1**

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We hereby consent to the incorporation by reference in this Registration Statement on Form S-3 of Summit Therapeutics Inc. of our report dated March 9, 2023 relating to the financial statements, which appears in Summit Therapeutics Inc.'s Annual Report on Form 10-K for the year ended December 31, 2022. We also consent to the reference to us under the heading "Experts" in such Registration Statement.

/s/ PricewaterhouseCoopers LLP

<br> Boston, Massachusetts<br> March 17, 2023

## Ex-Filing

[Summit Therapeutics Inc. S-3](summt-s3_031723.htm)

**Exhibit 107**

**Calculation of Filing Fee Tables**

**S-3**

(Form Type)

**Summit Therapeutics Inc.**

(Exact Name of Registrant as Specified in its Charter)

**Table 1: Newly Registered Securities**

---

| | | | | | | | | |
|:---|:---|:---|:---|:---|:---|:---|:---|:---|
| | **Security Type** | **Security Class Title (1)** | **Fee Calculation Rate** | **Amount Registered** | **Proposed Maximum Offering Price Per Security (2)** | **Maximum Aggregate Offering Price(2)** | **Fee Rate** | **Amount of Registration Fee** |
| Fees to be paid | Equity | Common Stock, par value $0.01 per share | 457 (c) | 19720291 | $1.42 | $28002813.22 | 0.00011020 | $3085.91 |
| Fees previously paid |  |  |  |  |  |  |  |  |
| **Total Offering Amounts** |  |  |  |  |  | $28002813.22 |  | $3085.91 |
| **Fees Previously Paid** |  |  |  |  |  |  |  | $0.00 |
| **Net Fees Due** |  |  |  |  |  |  |  |  |
|  |  |  |  |  |  |  |  | $3085.91 |

---

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1) The shares of common stock will be offered for resale by the selling stockholders pursuant to the prospectus contained in the registration statement to which this exhibit is attached. The registration statement registers the resale of an aggregate of 19,720,291 shares of the Registrant's common stock. Pursuant to Rule 416 under the Securities Act of 1933, as amended (the "Securities Act"), the shares of common stock being registered hereunder include such indeterminate number of shares of common stock as may be issuable upon stock splits, stock dividends, or other distribution, recapitalization or similar events.

(2) Estimated in accordance with Rule 457(c) solely for the purpose of calculating the total registration fee on the basis of $1.42 per share, which represents the average of the high and low prices of the Registrant's common stock as reported on the Nasdaq Global Market on March 10, 2023.