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Further Discussion of Study D9902B - Provenge, October 30, 2009
(System Info - 126674 TULL LORI 04/22/2010 11:33:42 TULL)
Date: Oct 30, 2009
Time: 1:00 PM
FDA Participants: Drs. Bross, Gupta, Hsu, Zhen
External Consultant: Dr. Ralph D’Agostino, Boston University, Boston, MA
Subject: Further discussion of Study D9902B
Dr. D’Agostino acknowledged that he had received the sponsor’s clinical study report and the FDA exploratory sensitivity analyses and had reviewed them.
We described to him the results after stratifying the time to docetexal as a salvage therapy, as he had suggested in the previous teleconference. These results still showed a difference between treatment arms consistent with a treatment effect. He was not surprised with these results.
He was impressed with the graph with four survival plots comparing patients subsequently treated with docetaxel with patients that did not receive subsequent docetaxel. He thought this analysis was helpful and did not suggest confounding by salvage treatment. He suggested providing the sample sizes of each arm on the graph.
He further stated that additional analyses would be unlikely to provide any useful information. When asked to suggest additional analyses, he suggested considering a competing risk analysis using time to docetexal therapy as an event. He said that this would likely bring the hazard rate closer to one, and he was not sure that this would provide a meaningful analysis.