June 23, 2017

 

VIA EDGAR

 

U.S. Securities and Exchange Commission

Division of Corporate Finance

Office of Healthcare and Insurance

100 F Street, N.E.

Washington, D.C. 20549

 

Attention:

 

Mary Beth Breslin – Legal

 

 

Keira Nakada/ Sharon Blume – Accounting

 

 

 

Re:

 

Mersana Therapeutics, Inc.

 

 

Registration Statement on Form S-1

 

 

Registration No. 333-218412

 

Ladies and Gentlemen:

 

Pursuant to Rule 461 under the Securities Act of 1933, as amended, Mersana Therapeutics, Inc., a Delaware corporation (the “Company”), hereby requests that the effective date for the registration statement referred to above be accelerated so that it will be declared effective at 4:00 p.m. Eastern Time on June 27, 2017, or as soon as possible thereafter. The Company hereby authorizes Marc A. Rubenstein and William J. Michener of Ropes & Gray LLP, counsel to the Company, to orally modify or withdraw this request for acceleration.

 

Please call Marc A. Rubenstein of Ropes & Gray LLP, counsel to the Company, at (617) 951-7826 as soon as the registration statement has been declared effective.

 

 

Very truly yours,

 

 

 

MERSANA THERAPEUTICS, INC.

 

 

 

 

 

 

By:

/s/ Anna Protopapas

 

Name:

Anna Protopapas

 

Title:

President and Chief Executive Officer