NOTICE OF PENDENCY OF CLASS ACTION: Please be advised that your rights may be affected by the above-captioned securities class action (the “Action”) 1 pending in the United States District Court for the Southern District of New York (the “Court”), if, during the period between December 21, 2020, and August 17, 2021, inclusive (“Settlement Class Period”), you purchased or otherwise acquired Sesen Bio, Inc. (“Sesen Bio” or the “Company”) common stock (“Sesen Bio Common Stock”), and/or Sesen Bio call options (“Sesen Bio Call Options”), and/or wrote Sesen Bio put options (“Sesen Bio Put Options”), and were damaged thereby.

NOTICE OF SETTLEMENT: Please also be advised that the Court-appointed Lead Plaintiffs, Ryan Bibb, Rodney Samaan, Lionel Dreshaj, and Benjamin Dreshaj (collectively, “Lead Plaintiffs”), on behalfofthemselves and the Settlement Class (as defined in ,r 22 below), have reached a proposed settlement of the Action for $21,000,000 in cash that, if approved, will resolve all claims in the Action (the “Settlement”).

Court-appointed Lead Counsel, Glancy Prongay & Murray LLP, have been prosecuting the Action on a wholly contingent basis since its inception. This means that Lead Counsel has not received any payment of attorneys’ fees for their representation of the Settlement Class and has advanced the funds to pay expenses necessarily incurred to prosecute this Action. Lead Counsel will apply to the Court for an award of attorneys’ fees for all Plaintiffs’ Counsel, including additional counsel The Law Offices of Frank J. Cruz, in an amount not to exceed 25% of the Settlement Fund.