
Sesen Bio, Inc. Securities Lawsuit Investigation
Shares drop up to 57% following FDA drug rejection and reports of clinical study violations
On Friday, August 13, Sesen Bio (NASDAQ: SESN) announced that it received a Complete Response Letter (CRL) from the FDA declining to approve an application for its drug candidate, Vicineum. Several days later STAT News reported that the clinical drug trial was marked by thousands of study violations, noncompliance, and signs of toxicity that were not previously disclosed by the company.
Sesen Bio stock plummeted 57% on August 13, 2021, and has continued to drop, causing significant harm to investors.
Lost money in Sesen Bio stock?
You may be eligible to recover your losses. Get a free and confidential consultation.
(Please provide number of shares, purchase date, and estimated losses.)
Sesen Bio stock drops following FDA rejection and report identifying thousands of violations
On August 13, biotechnology company Sesen Bio announced that it received a negative Complete Response Letter (CRL) from the FDA, determining that it could not approve an application for its leading drug candidate Vicineum, for the treatment of bladder cancer.
Five days later, on August 18, STAT News reported that the Vicineum clinical trial contained more than 2,000 violations, with 215 of those violations classified as “major.” The article also noted that the company may have failed to fully disclose all the potential health risks of the drug, noting that a patient died of liver failure in 2016, and two years later the company claimed at a urology conference that they had not encountered any drug-related deaths. In addition, STAT News reported that multiple doctors acting as investigators in the study had “back-dated” data and engaged in other unethical behavior, potentially putting patients at risk. According to STAT, these allegations were based on hundreds of pages of internal company documents reviewed by STAT reporters.
Our Securities Lawyers Have a Winning Record Against Companies Like Sesen Bio
Our securities lawyers have recovered over a billion dollars on behalf of our clients against behemoths, such as Chase Bank, Mastercard, and Anthem Blue Cross Blue Shield. Read more about our results.

You “shouldn’t presume that powerful banks and other powerful interests can just get away with doing bad things. Good, qualified counsel that are committed to a cause can usually figure out how to prosecute such cases effectively and prevail.”
–Eric Gibbs, award-winning securities attorney

Praise from the Courts
Federal judge in our AT&T class action:
“I’ve always found them to be extraordinary counsel in terms of their preparation and their professionalism.”
Federal judge in our Chase lawsuit (resulting in $100 million settlement):
They “fought tooth and nail, down to the wire” to achieve “the best settlement that they could under the circumstances.”
Read more about what judges say about us.
Our Featured Securities Team
Eileen Epstein Carney
Eileen represents investors and consumers harmed by financial fraud and other corporate misconduct. She also executes on the firm's strategic vision.
View full profileDave Stein
Dave represents clients in cases nationwide, ranging from securities and financial fraud cases to product liability, privacy, and data breach suits.
View full profileAmanda Karl
Amanda represents employees, consumers, and sexual assault survivors in complex class actions. She also leads the firm’s Voting Rights Task Force.
View full profileGibbs Law Group's Financial Fraud Experience
We have fought some of the most complex cases brought under federal and state laws nationwide, and our attorneys have been recognized with numerous awards and honors for their accomplishments, including Top 100 Super Lawyers in Northern California, Top Plaintiff Lawyers in California, The Best Lawyers in America, and rated AV Preeminent (among the highest class of attorneys for professional ethics and legal skills).