SESEN BIO INVESTORS

October 18, 2021 Filing Deadline in Class Action – Contact Lieff Cabraser

The law firm of Lieff Cabraser Heimann & Bernstein, LLP announces that class action litigation has been filed on behalf of investors who purchased or otherwise acquired the securities of Sesen Bio, Inc. (“Sesen Bio” or the “Company”) (NASDAQ: SESN) between December 21, 2020 and August 17, 2021, inclusive (the “Class Period”).

If you purchased or otherwise acquired Sesen Bio securities during the Class Period, you may move the Court for appointment as lead plaintiff by no later than October 18, 2021. A lead plaintiff is a representative party who acts on behalf of other class members in directing the litigation. Your share of any recovery in the actions will not be affected by your decision of whether to seek appointment as lead plaintiff. You may retain Lieff Cabraser, or other attorneys, as your counsel in the action.

Sesen Bio investors who wish to learn more about the litigation and how to seek appointment as lead plaintiff should click here, or email [e-mail], or call Sharon M. Lee of Lieff Cabraser at 1-800-541-7358.

Background on the Sesen Bio Securities Class Litigation

Sesen Bio, headquartered in Cambridge, Massachusetts, is a late-stage clinical company that purports to develop targeted fusion protein therapeutics for cancer treatments. The Company’s lead product is the drug Vicineum, a treatment for bacillus Calmette-Gurin (“BCG”)-unresponsive non-muscle invasive bladder cancer (“NMIBC”). In August 2019, Sesen Bio reported preliminary efficacy data from its ongoing Phase 3 clinical trial for Vicineum. In December 2020, the Company submitted its Biologics License Application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) for Vicineum.

The actions allege that throughout the Class Period, defendants failed to disclose to investors: (1) more than 2,000 violations of trial protocol in Sesen Bio's clinical trial for Vicineum, 215 of which were classified as “major”; (2) three clinical investigators were found guilty of “serious noncompliance,” including “back-dating data”; (3) Sesen Bio’s submission of tainted data related to the BLA for Vicineum; and (4) incidents of Vicineum leaking into patients’ bodies in the Company’s clinical trials, leading to side effects including liver failure and liver toxicity, and increasing the risks for fatal, drug-induced liver injury. Furthermore, defendants failed to reveal that, as a result of the foregoing, the Company’s BLA for Vicineum was not likely to be approved and that there was a reasonable likelihood that Sesen Bio would be required to conduct additional trials to show the efficacy and safety of Vicineum.