seser b i o 2020 Jefferies Healthcare Conference Thomas Cannell DVM, President & CEO For Investor Purposes Only June 2, 2020 NASDAQ: SESN FORWARD-LOOKING STATEMENTS This presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this presentation, including statements regarding our strategy, future operations, clinical development of our protein therapies, future financial position, future revenue ...

Table of Contents Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, $0.001 par value SESN The Nasdaq Stock Market UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2020 OR ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from ...

Sesen Bio, Inc. (SESN) Q1 2020 Results Conference Call May 11, 2020 8:00 AM ET Company Participants Erin Clark - Vice President of Investor Relations Dr. Thomas Cannell - President and Chief Executive Officer Dr. Chad Myskiw - Strategic Planning, CMC Monica Forbes - Chief Financial Officer Conference Call Participants John Newman - Canaccord Genuity Chris Howerton - Jefferies Sean Lee - H.C. Wainwright & Co Operator Ladies and gentlemen, thank you for standing by, and welcome to the Sesen Bio May 2020 Busin ...

May 2020 Business Update For Investor Purposes Only May 11, 2020 NASDAQ: SESN FORWARD-LOOKING STATEMENTS This presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this presentation, including statements regarding our strategy, future operations, clinical development of our protein therapies, future financial position, future revenues, projected costs, prospects, plans and objectives of manag ...

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Title of each class Trading Symbol(s) Name of each exchange on which registered Common Stock, $0.001 par value SESN The Nasdaq Global Market FORM 10-K (Mark One) [X] ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the fiscal year ended December 31, 2019 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from _____ to _____ Com ...

Sesen Bio, Inc. (SESN) Q4 2019 Earnings Conference Call March 16, 2020 8:00 AM ET Company Participants Erin Clark – Vice President-Corporate Strategy-Investor Relations Thomas Cannell – President and Chief Executive Officer Chad Myskiw – Strategic Planning, CMC Monica Forbes – Chief Financial Officer Conference Call Participants John Newman – Canaccord Chris Howerton – Jefferies Swayampakula Ramakanth – H.C. Wainwright Operator Ladies and gentlemen, thank you for standing by, and welcome to the Eleven Bioth ...

seser b i o March 2020 Business Update March 16, 2020 NASDAQ: SESN For investor purposes only FORWARD-LOOKING STATEMENTS This presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this presentation, including statements regarding our strategy, future operations, clinical development of our protein therapies, future financial position, future revenues, projected costs, prospects, plans and obj ...

seser i b O Regulatory Update December 16, 2019 FORWARD-LOOKING STATEMENTS We may not actually achieve the plans, intentions or expectations disclosed in our forwardlooking statements, and you should not place undue reliance on our forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed in the forward-looking statements we make as a result of various important factors, including: our projected financial position and estimated cash bu ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) [X] QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2019 OR [ ] TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-36296 Sesen Bio, Inc. (Exact name of registrant as specified in its charter) Delaware 26-2025616 (Sta ...

seser i b O 3Q 2019 Business Update November 12, 2019 FORWARD-LOOKING STATEMENTS This presentation contains forward-looking statements that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this presentation, including statements regarding our strategy, future operations, clinical development of our protein therapies, timing or probability of regulatory approval, future financial position, future revenues, projected costs, prospects, plans a ...