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FDA concerned about Taltorvic efficacy

March 16, 2012 11:54 PM UTC

FDA questioned the magnitude of Taltorvic ridaforolimus' efficacy benefit as a maintenance therapy for metastatic soft tissue or bone sarcoma given the Merck & Co. Inc. (NYSE:MRK) compound's adverse event profile, which included a "substantial" number of grade 3-4 events. In briefing documents released ahead of Tuesday's Oncologic Drugs Advisory Committee meeting to discuss the Taltorvic NDA, the agency highlighted the "small differences" in median progression-free survival and overall survival (OS) between the Taltorvic and placebo arms. FDA also said the fact that 14% of patients discontinued Taltorvic treatment due to an adverse event is of "particular concern in a drug intended for use as maintenance therapy." Only 2% of placebo patients discontinued treatment due to an adverse event.

FDA said Taltorvic led to median PFS of 16.1 weeks vs. 14 weeks with placebo in the single Phase III trial in the application (p<0.0006). Median OS was 20.8 months compared to 19.6 months for placebo (p=0.46). FDA said Taltorvic's adverse events are similar to those seen with other mammalian target of rapamycin ( mTOR; FRAP; RAFT1) inhibitors, including stomatitis, fatigue, infection, rash, cough, pneumonitis and renal failure. ...