Sesen Bio

Sesen Bio is a late-stage clinical company that previously focused on developing targeted fusion protein therapeutics for cancer treatment. Its lead product candidate, Vicineum, is a locally administered targeted fusion protein composed of an anti-epithelial cell adhesion molecule (EpCAM) antibody fragment tethered to a truncated form of Pseudomonas exotoxin A for the treatment of non-muscle invasive bladder cancer (NMIBC).

In February 2021, the FDA accepted Sesen Bio's Biologics License Application (BLA) for Vicineum to treat BCG-unresponsive NMIBC, granting Priority Review. However, in August 2021, the company received a Complete Response Letter from the FDA, requiring an additional Phase 3 clinical trial for potential resubmission. Following discussions with the FDA in March 2022, Sesen Bio aligned on most elements for the trial design and planned to meet again in mid-2022 to finalize outstanding items.

On July 15, 2022, Sesen Bio made the strategic decision to voluntarily pause further development of Vicineum in the US due to the incremental timeline and costs associated with the additional Phase 3 trial. The company shifted its primary focus to consummating a strategic transaction to maximize shareholder value while seeking a partner for Vicineum's further development.

In September 2022, Sesen Bio announced a pending merger with Carisma Therapeutics, a clinical-stage biopharmaceutical company developing immunotherapies based on engineered macrophages. This merger was approved by Sesen Bio's stockholders in March 2023, with the combined company operating under the name Carisma Therapeutics Inc. and trading on the Nasdaq under the ticker "CARM".

Upon closing the merger in March 2023, Sesen Bio declared a special cash dividend of USD 75 million (around USD 0.36 per share) to its stockholders and issued them Contingent Value Rights (CVRs) entitling them to potential proceeds from the sale of Vicineum and other assets, as well as a USD 30 million milestone payment under the Roche Asset Purchase Agreement.