UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Amendment No. )*

Under the Securities Exchange Act of 1934

CHECKPOINT THERAPEUTICS, INC.

(Name of Issuer)

Common Stock, $0.0001 Par Value

Class A Common Stock, $0.0001 Par Value

(Title of Class of Securities)

162828 107

(CUSIP Number)

(Name, Address and Telephone Number of Person Authorized to Receive Notices and Communications)

March 17, 2017

(Date of Event which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule l3G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box. ¨

Note: Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits. See §240.13d-7 for other parties to whom copies are to be sent.

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¹ Includes 7,000,000 shares of the Issuer’s Class A common stock and 2,702,705 shares of the Issuer’s common stock (including 1,000,000 shares of Issuer’s common stock underlying Warrants described below). As provided in the Issuer’s Amended and Restated Certificate of Incorporation, each share of Class A common stock is convertible at any time, at the option of the holder, into one share of the Issuer’s common stock. Pursuant to the terms of the Class A common stock, the Reporting Person is entitled to cast, for each share of Class A common stock held by the Reporting Person, the number of votes that is equal to one and one-tenth (1.1) times a fraction, the numerator of which is the sum of the shares of outstanding common stock and the denominator of which is the number of shares of outstanding Class A common stock. Accordingly, as long as the Reporting Person owns any shares of Class A common stock (and as long as no other person or entity owns any shares of Class A common stock), it will be able to control or significantly influence all matters requiring approval by the Issuer’s stockholders, including the election of directors and the approval of mergers or other business combination transactions. An aggregate 1,000,000 shares of Issuer common stock underlie Common Stock Warrants dated July 15, 2015, as amended by the Amended and Restated Common Stock Warrant dated December 12, 2016, issued by the Reporting Person to Lindsay A. Rosenwald, M.D., the Reporting Person’s Chairman, President and Chief Executive Officer and Michael S. Weiss, the Reporting Person’s Executive Vice Chairman, Strategic Development, pursuant to the Fortress Biotech, Inc. Long-Term Incentive Plan (the “Warrants”). The Warrants, which have an exercise price of $0.129 per share, are exercisable until July 15, 2035. The Reporting Person must reserve from its holdings of the Issuer’s common stock the shares underlying the Warrants until the Warrants are exercised. The foregoing description of the Warrants is not complete and is qualified in its entirety by reference to the full text of the form of the Amended and Restated Common Stock Warrant which is attached as Exhibit 7.01 and incorporated herein by reference. Mr. Weiss currently serves as the Chairman of the Issuer’s Board of Directors and also served as its Interim CEO and President from August 2015 until October 2015 and Executive Chairman from March 2015 until December 2016. Dr. Rosenwald currently serves as a member of the Issuer’s Board of Directors and, from November 2014 to August 2015, was the Issuer’s Interim Chief Executive Officer and President.

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This statement on Schedule 13D relates to the common stock and the Class A common stock of Checkpoint Therapeutics, Inc. (the “Issuer”). The Issuer’s principal executive office is located at 2 Gansevoort Street, 9^th Floor, New York, New York 10014.

² Based upon 7,000,000 shares of the Issuer’s Class A common stock outstanding and 18,218,575 shares of the Issuer’s common stock outstanding as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 10, 2017.

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The Reporting Person is filing this Schedule 13D as a result of the acquisition of 721,699 shares of the Issuer’s common stock on March 17, 2017 (the “2017 Annual Equity Grant”). The Issuer issued the 2017 Annual Equity Grant pursuant to the terms of the Founders Agreement, entered into by the Reporting Person and the Issuer on March 17, 2015, and amended and restated on July 11, 2016 (the “Founders Agreement”). The Founders Agreement provides that, in exchange for the time and capital expended by the Reporting Person in the formation of the Issuer and the identification of specific assets the acquisition of which result in the formation of a viable emerging growth life science company, the Issuer (i) will issue annually to the Reporting Person, on the anniversary date of the original Founders Agreement, shares of common stock equal to 2.5%  of the fully-diluted outstanding equity of the Issuer at the time of issuance (an “Annual Equity Grant”); and (ii) pay an equity fee in shares of Issuer common stock, equal to 2.5% of the gross amount of any equity or debt financing for the Issuer or any of its respective subsidiaries that occurs after the effective date of the original Founders Agreement and ending on the date when the Reporting Person no longer has majority voting control in the Issuer’s voting equity (an “Offering Equity Grant”). The foregoing description of the Founders Agreement is qualified in its entirety by reference to the full text of the Founders Agreement which is attached as Exhibit 7.02 and incorporated herein by reference. The Issuer previously issued 289,085 and 688,755 shares of common stock during 2015 and 2016, respectively, as Annual Equity Grants, and 3,166 shares of common stock in 2016 as an Offering Equity Grant. The Issuer issued 7,000,000 shares of Class A common stock to the Reporting Person on November 10, 2014. Except for the 2017 Annual Equity Grant, all of the shares of common stock and Class A common stock to which this Schedule 13D relates were acquired prior to the Issuer’s Form 10 being declared effective by the U.S. Securities and Exchange Commission (the “SEC”) on September 8, 2016.

The Reporting Person obtained shares of the Issuer’s common stock on March 17, 2017 pursuant to the Founders Agreement. The Reporting Person does not have any present plans or proposals that relate to or would result in: (i) the acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer, except for 1,000,000 shares underlying the Warrants described in Footnote 1 and any additional Annual Equity Grants or Offering Equity Grants that may be made pursuant to the Founders Agreement as further described in Item 3 above; (ii) an extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of the Issuer’s subsidiaries; (iii) a sale or transfer of a material amount of assets of the Issuer or any of the Issuer’s subsidiaries; (iv) any change in the present board of directors or management of the Issuer; (v) any material change in the present capitalization or dividend policy of the Issuer; (vi) any other material change in the Issuer’s business or corporate structure; (vii) changes in the Issuer’s charter, bylaws or instruments corresponding thereto or other actions which may impede the acquisition of control of the Issuer by any person; (viii) causing a class of securities of the Issuer to be delisted from a national securities exchange or to cease to be authorized to be quoted in an inter-dealer quotation system of a registered national securities association; (ix) a class of equity securities of the Issuer becoming eligible for termination of registration pursuant to Section 12(g)(4) of the Securities Exchange Act of 1934; or (x) any action similar to any of those enumerated above.

(a) – (c) The Reporting Person is the beneficial owner of 9,702,705 shares of the Issuer’s Class A common stock and the Issuer’s common stock. The Reporting Person’s (i) 2,702,705 shares of the Issuer’s common stock represent 14.8% of all outstanding shares of the Issuer’s common stock, (ii) 7,000,000 shares of the Issuer’s Class A common stock represent 100% of all outstanding shares of the Issuer’s Class A common stock and (iii) 9,702,705 shares of the Issuer’s Class A common stock and the Issuer’s common stock represent 38.5% of all outstanding shares of the Issuer’s Class A common stock and the Issuer’s common stock combined, in each case based on 7,000,000 shares of the Issuer’s Class A common stock outstanding and 18,218,575 shares of the Issuer’s common stock outstanding as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the SEC on May 10, 2017. The Reporting Person has sole voting power over the 9,702,705 shares of the Issuer’s Class A common stock and the Issuer’s common stock beneficially owned. The Reporting Person has sole dispositive power over 7,000,000 shares of the Issuer’s Class A common stock and 1,702,705 shares of the Issuer’s common stock, and shared dispositive power over 1,000,000 shares of the Issuer’s common stock that underlie the Warrants. See Footnote 1 for a description of the Warrants.

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(d)       Except with respect to the Warrants described in Footnote 1, no person has the power to direct the receipt of dividends on or the proceeds of sales of, the shares of common stock and Class A common stock owned by the Reporting Person.

(e)       Not Applicable.

Reference is made to the Founders Agreement in Item 3 and the Warrants in Footnote 1 above.

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SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.