CP-037 Efficacy of abiraterone in the treatment of prostate cancer

Abstract

BackgroundHormone treatment based on analogues of gonadotropin releasing hormone (GnRH) with antiandrogens is the first-line treatment for prostate cancer. This treatment produces a PSA reduction, improvement of symptoms and tumour regression. When PSA increases again it is considered to have developed resistance and other treatment lines such as abiraterone are used.Abiraterone is an androgen synthesis inhibitor in the testes, adrenals and prostate tumour tissue.PurposeTo analyse the response to, and safety of, abiraterone in the population of a tertiary level hospital.Material and methodsA retrospective observational study was carried out including all patients who started on abiraterone from 2011 to present. Demographical, diagnostic, therapeutic and clinical variables were gathered.The response was assessed by a 50% PSA reduction or more as compared to baseline values. To assess the safety, abiraterone-related adverse events were recorded.Outpatient dispensing application Farmatools and electronic medical records were used for patient identification and data collection.Results18 patients were included, 89% diagnosed with metastatic prostate cancer. 50% had poor tumour differentiation with high aggressiveness (Gleason 7–10).As a first-line of treatment, 83% received GnRH analogues plus an antiandrogen, 11% GnRH analogues alone and 6% ketoconazole. No patients orchiectomized. As a second-line treatment, 28% received docetaxel, 44% estramustine, 22% abiraterone and 6% ketoconazole. Abiraterone was started as third-line or later treatment and after tumour progression, except in 3 patients who received it as second-line treatment.44% were considered responders and 56% non-responders because of an increase or non-reduction of PSA.The median duration of treatment was 5 months (1–25). In all cases, the reason for suspension was disease progression.17% had fatigue as the only adverse effect.ConclusionAbiraterone is a well-tolerated drug that has shown low activity in previously-treated prostate cancer patients who had responded poorly to ketoconazole, docetaxel and estramustine.Best responding patients were those who received only GnRH analogues as pre-treatment.References and/or AcknowledgementsNo conflict of interest.