I think regulators are going to be very careful with bladder cancer risk because of mechanism of action. At minimum, large post marketing studies will be required.
Agreed with respect to the requirement for a large post-marketing study.
The complete response letter requests additional clinical data to allow a better assessment of the benefit-risk profile for dapagliflozin. This includes clinical trial data from ongoing studies and may require information from new clinical trials.
Dapagliflozin became a longshot for approval on the first review cycle after the FDA advisory panel voted 9-6 against in Jul 2011 (#msg-65362040).