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NDA 21-240. Study MP-US-M01. Federal Food, Drug, and Cosmetic Act of 1962. Substantial Evidence = Adequate and well-controlled investigations Modernization Act 1997
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NDA 21-240 Study MP-US-M01
Federal Food, Drug, and Cosmetic Act of 1962 • Substantial Evidence = Adequate and well-controlled investigations • Modernization Act 1997 • Data from one adequate and well controlled clinical investigation and confirmatory evidence can be considered substantial evidence by the Agency
Reasons a Single Study is Generally Not Adequate • Any trial may be subject to unanticipated, undetected, systematic biases that could lead to flawed conclusions • Inherent variability may produce a positive trial by chance alone • 1/40 studies of ineffective drugs will be positive (p=0.05)
Causes of False-Positive Studies (Tannock, JCO Nov 2000) • Chance • Prognostic Factor Imbalances • Multiplicity • Low Prior Probability a New Treatment will be a Therapeutic Advance • 1/3 “positive trials” are false positive in this hypothetical setting
Hypothetical Situation - Low Prior Probability of Therapeutic Advance
Role of Tamoxifen in the Treatment of Metastatic Melanoma • Cocconi, et al NEJM August 1992. • Dacarbazine + Tamoxifen vs. Dacarbazine • Survival 48 weeks vs. 29 weeks, p=0.02 • Subsequent Non-Confirmatory Trials • ECOG (Falkson, et al; JCO May 1998) • Intergroup (Chapman, et al; JCO 1999) • NCI Canada (Rusthoven, et al; JCO 1996) • Mayo (Creagan, et al; JCO June 1999) • U. Pittsburgh (Agarwala, et al; Cancer 1999)
FDA Guidance for IndustryProviding Clinical Evidence of Effectiveness for Human Drug and Biological Products • Reliance on a single study “whether alone or with substantiation from related trial data leaves little room for study imperfections or nonsupportive information” • Limited to where confirmation would be practically or ethically impossible
What Makes a Single Study Persuasive? • Large, multicenter study • Appropriate Design • Flawless conduct • Minimal possibility of bias due to baseline imbalances, unblinding and post-hoc changes in analysis
What Makes a Single Study Persuasive? • Results should reflect a clear hypothesis documented in the protocol • Statistically persuasive
Review • Randomized, Controlled Multicenter Trial, BUT it is a Single Trial • ITT Analysis of the Primary Endpoint was not Statistically Significant
Apparent Survival Benefit in a Subset Analysis - Liver Metastases • BUT there were imbalances in prognostic factors favoring the histamine/IL-2 arm • AND the FDA’s adjusted analyses showed that imbalances influenced the observed treatment effect
Questions • Does the survival difference in the planned primary analysis of this single study, the ITT analysis of survival, represent substantial evidence of the efficacy of histamine dihydrochloride as an adjunctive treatment with IL-2 for patients with metastatic melanoma?
Questions • Does the survival difference observed in the subgroup of patients with liver metastases in this single study represent substantial evidence of the efficacy of histamine dihydrochloride as an adjunctive treatment with IL-2 for patients with melanoma that has metastasized to the liver?
Questions • In view of the efficacy results, is the safety profile of the histamine/IL-2 combination acceptable?