Sesen Bio, Inc.

245 First Street, Suite 1800

Cambridge, MA 02142

June 6, 2018

VIA EDGAR

Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549

Re: Sesen Bio, Inc.

Registration Statement on Form S-3

Filed March 19, 2018

File No. 333-223750

Request for Acceleration of Effective Date

Ladies and Gentlemen:

Pursuant to Rule 461 of the General Rules and Regulations under the Securities Act of 1933, as amended, Sesen Bio, Inc. (the “Company”), formerly Eleven Biotherapeutics, Inc., hereby requests that the Securities and Exchange Commission accelerate the effective date of the above-referenced Registration Statement on Form S-3, as amended to date, and declare such Registration Statement effective as of 4:00 p.m., Eastern Daylight Time, on June 8, 2018, or as soon thereafter as possible.

Please feel free to direct any questions or comments concerning this request to Steve Abrams of Hogan Lovells US LLP at (267) 675-4671.

Very truly yours,

Sesen Bio, Inc.

/s/ Stephen A. Hurly
By:	Stephen A. Hurly
Title:	President and Chief Executive Officer