An unexpected complete response letter (CRL) from the FDA has thrown a wrench into Sesen Bio Inc.’s commercial launch plans for Vicineum (oportuzumab monatox) in high-risk BCG-unresponsive non-muscle invasive bladder cancer (NMIBC). The company, which has spent the past few months completing its commercial build phase and hiring sales reps ahead of the Aug. 18 PDUFA date, instead must now address outstanding clinical and statistical data and analyses, in addition to CMC issues, cited in the CRL.