Sesen Bio Stock Crashes As FDA Shoots Down Its Bladder Cancer Pitch

The FDA issued a Complete Response Letter (CRL) to Sesen Bio Inc's SESN bladder cancer candidate Vicineum.
The Company acquired the antibody-drug conjugate in the buyout of Viventia back in 2016.
Sesen described the reason for the CRL as a combination of manufacturing issues and requests for more data and statistical analyses.
The news comes unexpected as in July, Sesen completed a Late-Cycle Meeting with the FDA concluding that no confirmatory trial is necessary.
Vicineum uses a recombinant fusion protein attached to a genetically engineered peptide designed to target specific antigens on the surface of tumor cells to treat cancers.
The FDA had given Sesen priority review for the program in February.
Sesen had submitted data from an open-label Phase 3 study that enrolled 133 patients with high-risk, BCG-unresponsive non-muscle invasive bladder cancer.
The patients had previously been on BCG immunotherapy, and the most recent data came from 93 individuals whose cancer had not spread from the bladder into the muscle or other tissue.
Sesen reported that 39% of those patients achieved a complete response after three months.
Price Action: SESN shares are down 13.3% at $1.83 during the premarket session on the last check Monday.
Related content: Benzinga's Full FDA Calendar.