Andrew Hack - Jun 12, 2025 Form 4 Insider Report for Mersana Therapeutics, Inc. (MRSN)

Role: Director
Signature: /s/ Andrew Hack
Stock symbol: MRSN
Transactions as of: Jun 12, 2025
Transactions value $: $0
Form type: 4
Date filed: 6/13/2025, 05:10 PM
Previous filing: Dec 13, 2024
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Hack Andrew A. F.	Director	C/O BAIN CAPITAL LIFE SCIENCES INVESTORS, 200 CLARENDON STREET, BOSTON	/s/ Andrew Hack	2025-06-13	0001657434

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Value $	Shares	Change %	* Price $	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	MRSN	Stock Option (right to buy)	Award	$0	+61.5K		$0.00	61.5K	Jun 12, 2025	Common Stock	61.5K	$0.36	Direct	F1

Showing 1 to 1 of 1 entries

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	The award will vest in full on the earlier of the first anniversary of the date of grant or the date of the 2026 Annual Meeting of Stockholders of the Issuer, subject to the Reporting Person's continuous service with the Issuer on such vesting date.