6 Years of experience with abiraterone acetate at SAMS day care hospital

Abstract

Introduction: The reduction of PSA is one of the effects of abiraterone acetate [1] and it is considered one indicator of therapy success. It has been increasingly used in early stages of prostate cancer metastatic disease, with proven results in patients’ overall survival [2–4]. At SAMS Hospital it began to be used in March 2012, and its significance has grown over the last six years with visible positive effects on patients’ life quality. Its heavy financial impact reinforces the meaning of studying the cost/ benefit ratio, comparing our reality with the expected results described in the international literature. This study aimed to evaluate the relationship between the duration of treatments with abiraterone and the % reduction of PSA values in patients with metastatic castration-resistant (mCRPC) or hormone-sensitive (mHSPC) prostate cancer.

Materials and methods: This study was conducted after authorization by the ethics commission of SAMS-SBSI institution. The study population corresponds to all patients whom was prescribed the abiraterone acetate, between March 2012 and March 2018, for a total number of 38 individuals. Among these, 6 were excluded (death or loss to follow-up in a 2 month period - inclusion criteria) and the remaining 32 were included as long as they met the criteria of having at least 2 PSA values. We then divided them in 3 groups according to the therapeutic indications: group 1 (n = 4): mCRPC after chemotherapy; group 2 (n = 27): mCRPC after androgen deprivation therapy (ADT); group 3 (n = 1): high risk mHSPC in combination with ADT. A simple statistical analysis approach was used on the group 2 results.

Results: Outcomes to date including all the patients (some are still on therapy), show that 62.5% received treatment up to 1 year; about 28.1% did it between 1 and 2 years; and 9.4% of patients had a treatment duration of more than 3 years. The overall percentage of patients with PSA reduction ≥50% was 51.3%. The median duration of treatment for all the patients in group 2 was 13 months. If we isolate only the patients with proven PSA reduction, the median treatment time grows up to 20 months.

Discussion and conclusions: Although the sample of patients that already completed treatments is still too small to yield statistically significant results, there seems to be a growing statistical trend between the maximum % of PSA reduction and the total duration of treatment, and it seems that the greater that percentage of PSA reduction is, the longer their treatment lasts. No correlations were observed between the duration of treatment and other variables such as patients’ age at the beginning of treatment; the time to first PSA decrease; or the % of first PSA reduction. The median duration of treatment of 13 months is a little less than the 13.8 months observed in the clinical trials [5], but this time is expected to increase as we still have patients with ongoing treatments.