Background Abiraterone is approved for patients who have metastatic castration resistant prostate cancer (mCRPC). It irreversibly inhibits the products of the CYP17 gene, blocking the synthesis of androgens. Increased mineralocorticoids due to CYP17 inhibition may result in hypertension, hypokalaemia and fluid retention. Patients are at risk of adrenal insufficiency and require concurrent use of corticosteroids.

Purpose To assess the safety of abiraterone for mCRPC in clinical practice in a regional hospital.

Material and methods A retrospective longitudinal study was performed in patients who were treated with abiraterone for mCRPC during the study period (December 2011 to October 2015). Patients were followed-up until the end of therapy. Variables collected from medical records were: age, performance status (PS), treatment duration, type of metastases and chemotherapy status (prior chemotherapy or naïve). We analysed adverse events (AE) associated with abiraterone, their severity and if they were the cause of ending treatment.

Results 82 patients were included. Median age was 76 (52–93) years and 6 (7%) had a PS ≥2. Median duration of treatment was 6.7 months (0.47–31.93). 64 patients (78%) had bone metastases, 11 (13%) ganglionar metastases and 7 (9%) both. 37 patients (45%) had received previous docetaxel therapy and 45 (55%) were chemotherapy naive. Common AE attributable to abiraterone were recorded: fluid retention (21%), hyperglycaemia (11%), hypertension (12%), hypokalaemia (2%) and hepatotoxicity (11%). Other AE (60%) observed were: asthenia (25%), diarrhoea (6%), constipation (5%), thrombocytopenia (1%), muscle cramps (5%) and hyperkalaemia (7%). The most severe AE found was hepatotoxicity grade 3 or 4 (elevation in aminotransferase levels >5.0–20.0 times the upper limit of normal) in 4 (5%) patients. 6 patients (7%) had to stop the treatment due to toxicity: hepatotoxicity (4), asthenia (1) and perforated bowel (1).

Conclusion The results obtained were consistent with the AE observed in the pivotal trial (study 301,302). Hyperkalaemia and thrombocytopenia were not reported in the European Public Assessment Report (EPAR). Toxicity was significant but acceptable in most patients treated with abiraterone plus prednisone.

No conflict of interest.