Safety and efficacy of abiraterone acetate (AA) in patients aged 75 or more with metastatic castration-resistant prostate cancer (mCRPC) in both pre-chemotherapy or post-chemotherapy settings: Real-life experience from thirteen Italian centers.

Abstract

209 Background: Prostate cancer affects mainly elderly patients (pts) that have different comorbidities. AA is a selective androgen synthesis inhibitor that showed the efficacy in either chemotherapy (CT) naive pts or those pretreated with docetaxel. Its oral administration and good tolerability make it a manegeable treatment for elderly mCRPC pts. Methods: We collected retrospectively data regarding mCRPC pts aged ≥75 years treated with AA in 13 Italian Centers since April 2013. The median age was 79 years (r. 75-90) with 48% of pts being octagerians. Post CT pts had more extensive disease, higher baseline PSA and ECOG PS. Nearly all the pts had comorbidities, the most frequent being hypertension present in 146 pts (58%), 43 pts (17%) had diabetes type II. We evaluated duration of the AA treatment, overall response rate (ORR), 50% PSA decline, time to progression (TTP) and overall survival (OS). We reported all toxicities observed. Results: A total of 252 pts ,147 pre treated with docetaxel and 105 chemo naive, were included. Median duration of treatment with AA was 8,6 months in post CT and 11,5 in CT naive pts. ORR was 35,3% in pre docetaxel and 27,4% in post docetaxel group. 64 pts (65%) and 51 pts (46%) obtained 50% PSA reduction in pre and post docetaxel group, respectively. Median TTP was 8,6 in post docetaxel and 11,9 in CT naive pts. We observed a median OS of 13,8 months in post CT group while for CT naive pts data were not yet mature. AA was well tolerated with only 8 pts (3,2%) who discontinued treatment due to toxicity, while in 4 pts (1,6%) temporary dose reductions were performed. The most frequent G3 toxicities were hypertension and liver toxicity with 4 pts (1,6%) and 5 pts (2%), respectively. After progressing on AA, 85 pts (34%) received at least one subsequent treatment. 40 pts (15,9%) are still on treatment with AA. Conclusions: Even if almost all the pts reported comorbidities at AA start and 72 pts (28,6%) had PS ECOG 2, only a small proportion of them discontinued the treatment due to toxicity confirming that AA is well tolerated and efficient treatment also for elderly patients.