Sesen Bio Completes Successful CMC Type B Pre-BLA Meeting With FDA

CAMBRIDGE, Mass.– Sesen Bio (Nasdaq: SESN), a late-stage clinical company developing targeted fusion protein therapeutics for the treatment of patients with cancer, today reported the successful completion of a constructive Type B pre-BLA meeting with the FDA regarding the final Chemistry, Manufacturing and Controls (CMC) content of the Company’s Biologics License Application (BLA) for Vicinium. As previously announced, the Company expects to initiate the submission of the BLA for Vicinium in December 2019.

“After four highly collaborative and productive meetings with the FDA in 2019, we feel increasingly confident in the regulatory path forward for Vicinium,” said Dr. Thomas Cannell, president and chief executive officer of Sesen Bio.

Sesen Bio reached agreement with the FDA on the final content of the BLA and no further meetings were requested by the FDA at this time. The Company also gained a clear understanding of the FDA’s requirements for the process performance qualification (PPQ) campaign for bulk drug substance and drug product manufacturing. In addition, the Company continues to work in partnership with the FDA to accelerate the timing of the Pre-License Inspection (PLI) of the drug substance manufacturer, which is anticipated to expedite review of the BLA.

Additional details on regulatory progress in support of the potential approval of Vicinium are expected to be announced this December.

Key December 2019 Events

• Anticipated initiation of BLA submission under a Rolling Review
• Sesen Bio Regulatory Update.-Bio Space