SESN CLASS ACTION NOTICE: Glancy Prongay & Murray LLP Files Securities Fraud Lawsuit Against Sesen Bio, Inc.

Glancy Prongay & Murray LLP (“GPM”), announces that it has filed a class action lawsuit in the United States District Court for the Southern District of New York captioned Bibb v. Sesen Bio, Inc.,et al., (Case No. 21-cv-7025) on behalf of persons and entities that purchased or otherwise acquired Sesen Bio, Inc. (“Sesen Bio” or the “Company”) (NASDAQ: SESN) securities between December 21, 2020 and August 17, 2021, inclusive (the “Class Period”). Plaintiff pursues claims under Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 (the “Exchange Act”).

Investors are hereby notified that they have 60 days from this notice to move the Court to serve as lead plaintiff in this action.

If you suffered a loss on your Sesen Bio investments or would like to inquire about potentially pursuing claims to recover your loss under the federal securities laws, you can submit your contact information at https://www.glancylaw.com/cases/sesen-bio-inc/. You can also contact Charles H. Linehan, of GPM at 310-201-9150, Toll-Free at 888-773-9224, or via email at shareholders@glancylaw.com or visit our website at www.glancylaw.com to learn more about your rights.

Sesen Bio is a late-stage clinical company that purports to advance targeted fusion protein (“TFP”) therapeutics for cancer treatments. Its most advanced product candidate is Vicineum (VB4-845), a locally administered TFP developed as a treatment of bacillus Calmette-Guérin (“BCG”)-unresponsive non-muscle invasive bladder cancer (“NMIBC”). Sesen Bio reported preliminary efficacy data from its ongoing Phase 3 clinical trial for Vicineum, the VISTA trial, in August 2019.

On December 21, 2020, the Company announced that it had submitted its Biologics License Application (“BLA”) to the U.S. Food and Drug Administration (“FDA”) for Vicineum for the treatment of BCG-unresponsive NMIBC.

On August 13, 2021, Sesen Bio announced that the FDA declined to approve its BLA for Vicineum in its current form. The FDA provided certain “recommendations specific to additional clinical/statistical data and analyses in addition to Chemistry, Manufacturing and Controls (CMC) issues pertaining to a recent pre-approval inspection and product quality.”

On this news, the Company’s share price fell $2.80, or 57%, to close at $2.11 per share on August 13, 2021, on unusually heavy trading volume.

Then, on August 16, 2021, Sesen Bio further revealed that “it appears that [the Company] will need to do a clinical trial to provide the additional efficacy and safety data necessary for the FDA to assess the benefit-risk profile, which is the basis for approval.” As a result, the Company expected that it could not resubmit its BLA until 2023.

On this news, the Company’s share price fell $0.89, or 42%, to close at $1.22 per share on August 16, 2021, on unusually heavy trading volume.

Then, on August 18, 2021, before the market opened, the health and medicine news site STAT published an article entitled “Sesen Bio trial of cancer drug marked by misconduct and worrisome side effects, documents show.” Citing “hundreds of pages of internal documents” and “three people familiar with the matter,” the article detailed that the clinical trial for Vicineum was “marked by thousands of violations of study rules, damning investigator conduct, and worrying signs of toxicity the company did not publicly disclose.”

On this news, the Company’s share price fell $0.20, or 13%, to close at $1.31 per share on August 18, 2021, on unusually heavy trading volume.

The complaint filed in this class action alleges that throughout the Class Period, Defendants made materially false and/or misleading statements, as well as failed to disclose material adverse facts about the Company’s business, operations, and prospects. Specifically, Defendants failed to disclose to investors: (1) that Sesen Bio’s clinical trial for Vicineum had more than 2,000 violations of trial protocol, including 215 classified as “major”; (2) that three of Sesen Bio’s clinical investigators were found guilty of “serious noncompliance,” including “back-dating data”; (3) that Sesen Bio had submitted the tainted data in connection with the BLA for Vicineum; (4) that Sesen Bio’s clinical trials showed that Vicineum leaked out into the body, leading to side effects including liver failure and liver toxicity, and increasing the risks for fatal, drug-induced liver injury; (5) that, as a result of the foregoing, the Company’s BLA for Vicineum was not likely to be approved; (6) that, as a result of the foregoing, there was a reasonable likelihood that Sesen Bio would be required to conduct additional trials to support the efficacy and safety of Vicineum; and (7) that, as a result of the foregoing, Defendants’ positive statements about the Company’s business, operations, and prospects were materially misleading and/or lacked a reasonable basis.

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If you purchased or otherwise acquired Sesen Bio securities during the Class Period, you may move the Court no later than 60 days from this notice ask the Court to appoint you as lead plaintiff. To be a member of the Class you need not take any action at this time; you may retain counsel of your choice or take no action and remain an absent member of the Class. If you wish to learn more about this action, or if you have any questions concerning this announcement or your rights or interests with respect to these matters, please contact Charles Linehan, Esquire, of GPM, 1925 Century Park East, Suite 2100, Los Angeles California 90067 at 310-201-9150, Toll-Free at 888-773-9224, by email to shareholders@glancylaw.com, or visit our website at www.glancylaw.com. If you inquire by email please include your mailing address, telephone number and number of shares purchased.

This press release may be considered Attorney Advertising in some jurisdictions under the applicable law and ethical rules.

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