An ambispective observational study in the safety and efficacy of abiraterone acetate in the French temporary authorizations for use (ATU): Predictive parameters of response.

Abstract

149 Background: The Temporary Authorizations for Use (ATU) procedure is an exceptional measure making available medicinal products that have not yet been granted a Marketing Authorisation. Abiraterone acetate (AA) was available for ATU since December 2010 in France. We then decided to evaluate the tolerance and efficacy of this treatment and identify predictive factors of response. Methods: 82 centers were contacted and clinical data were reported in two months (15th July-19th September 2011). Patients were defined as non-responders in case of interruption of AA due to disease progression or death. PSA values were recorded at each medical visit. Reported toxicities were also recorded. Statistical analyses were descriptive and predictive factors were determined. Results: A total of 18 centers accepted to participate in this study including 381 patients. Median age at diagnosis was 63 years. The Gleason score (n=320) were 4-6, 7, and 8-10 in 13.4%, 36.9% and 49.7%, respectively. Before AA, the type of metastasis was bone only, organs only, and bone+organs in 45.4%, 7.9% and 46.7%, respectively. Median PSA before CT and before AA was 58.1 and 137.5 ng/ml, respectively. Median duration of hormonotherapy (HT) before any CT was 34 months. Median duration of CT before AA was 6.1 months with a median number of CT lines of one. Median duration of AA was 117 days. In the non-responders group (n=114), median duration of AA was significantly shorter than in the responders group (n=267), 87 days vs 147 days, respectively (p<0.0001). One third of the patients in the responders group presented a PSA increase over time but continued AA as they clinically improved. Only 13 patients stopped AA for grade 3-4 toxicities. GIeason 8-10 and the number of CT lines (>1) before AA were identified as independent predictive factors of non response. Conclusions: This report is the largest ambispective observational study of AA in an ATU process. PSA values during AA treatment were used as a good indicator of progression. GIeason 8-10 and the number of CT lines (>1) before AA were identified as independent predictive factors and therefore could be used for further strategies in this setting.