0000935836-23-000535.txt : 20230731 0000935836-23-000535.hdr.sgml : 20230731 20230731135545 ACCESSION NUMBER: 0000935836-23-000535 CONFORMED SUBMISSION TYPE: 3 PUBLIC DOCUMENT COUNT: 1 CONFORMED PERIOD OF REPORT: 20230727 FILED AS OF DATE: 20230731 DATE AS OF CHANGE: 20230731 REPORTING-OWNER: OWNER DATA: COMPANY CONFORMED NAME: EcoR1 Capital, LLC CENTRAL INDEX KEY: 0001587114 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 3 SEC ACT: 1934 Act SEC FILE NUMBER: 001-38129 FILM NUMBER: 231126454 BUSINESS ADDRESS: STREET 1: 357 TEHAMA STREET #3 CITY: SAN FRANCISCO STATE: CA ZIP: 94103 BUSINESS PHONE: 415-448-6534 MAIL ADDRESS: STREET 1: 357 TEHAMA STREET #3 CITY: SAN FRANCISCO STATE: CA ZIP: 94103 ISSUER: COMPANY DATA: COMPANY CONFORMED NAME: Mersana Therapeutics, Inc. CENTRAL INDEX KEY: 0001442836 STANDARD INDUSTRIAL CLASSIFICATION: PHARMACEUTICAL PREPARATIONS [2834] IRS NUMBER: 000000000 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 BUSINESS ADDRESS: STREET 1: 840 MEMORIAL DRIVE CITY: CAMBRIDGE STATE: MA ZIP: 02139 BUSINESS PHONE: 617-498-0020 MAIL ADDRESS: STREET 1: 840 MEMORIAL DRIVE CITY: CAMBRIDGE STATE: MA ZIP: 02139 FORMER COMPANY: FORMER CONFORMED NAME: MERSANA THERAPEUTICS INC DATE OF NAME CHANGE: 20080813 3 1 ownership.xml X0206 3 2023-07-27 0 0001442836 Mersana Therapeutics, Inc. MRSN 0001587114 EcoR1 Capital, LLC 357 TEHAMA STREET #3 SAN FRANCISCO CA 94103 0 0 1 0 Common Stock 19364688 I See Notes 1 and 2 The filing persons (the "Filers") are EcoR1 Capital, LLC ("EcoR1"), Oleg Nodelman, and EcoR1 Capital Fund Qualified, L.P. ("Qualified Fund"). EcoR1 is the general partner and investment adviser of private funds, including Qualified Fund (collectively, the "Funds"). Mr. Nodelman is the manager and controlling owner of EcoR1. EcoR1 is filing this Form 3 for itself, Mr. Nodelman and Qualified Fund. The Filers are filing this Form 3 jointly, but not as a group, and each expressly disclaims membership in a group within the meaning of Rule 13d-5(b) under the Securities Exchange Act of 1934. The Funds hold these securities directly for the benefit of their investors. EcoR1 may be deemed to indirectly beneficially own them as the investment adviser to the Funds. Mr. Nodelman may be deemed to indirectly beneficially own them as the control person of EcoR1. The Filers disclaim beneficial ownership of the securities except to the extent of their respective pecuniary interests therein. Qualified Fund directly holds 18,260,899 of the shares of Common Stock reported in this Form 3. /s/ Oleg Nodelman 2023-07-28