UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)
of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): July 1, 2025

MERSANA THERAPEUTICS, INC.

(Exact name of registrant as specified in its charter)

Delaware

001-38129

04-3562403

(State or other jurisdiction
of incorporation)

(Commission

File Number)

(IRS Employer

Identification No.)

840 Memorial Drive Cambridge, Massachusetts		02139
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s telephone number, including area code: (617) 498-0020

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

¨ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

¨ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

¨ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

¨ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $0.0001 par value	MRSN	The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

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 13(a) of the Exchange Act. ¨

Item 1.02 Termination of a Material Definitive Agreement.

On July 1, 2025, Mersana Therapeutics, Inc. (the “Company”) entered into a letter agreement with Oxford Finance LLC (“Oxford”) and the Lenders (as defined below) providing for the repayment by the Company of all amounts owed under the loan and security agreement, dated October 29, 2021 (as subsequently amended, restated and/or otherwise modified, the “Loan Agreement”), by and among the Company, Oxford, as collateral agent (the “Collateral Agent”), and the lenders from time to time party thereto (the “Lenders”). On July 1, 2025, upon payment by the Company of approximately $17.9 million, all of the Company’s indebtedness and obligations to the Collateral Agent and Lenders under the Loan Agreement and any other related loan and collateral security documents was deemed paid and discharged in full.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	MERSANA THERAPEUTICS, INC.

Date: July 3, 2025	By:	/s/ Brian DeSchuytner
		Brian DeSchuytner
		Senior Vice President, Chief Operating Officer and Chief Financial Officer

Mersana Therapeutics Inc. filed SEC Form 8-K: Termination of a Material Definitive Agreement