Safety of long-term exposure to abiraterone acetate in patients with castration-resistant prostate cancer and concomitant cardiovascular risk factors

Background: We aimed to evaluate the long-term safety profile of abiraterone in patients with metastatic castration-resistant prostate cancer (mCRPC) with controlled cardiovascular comorbidities or risk factors. Methods: We retrospectively analysed the clinical charts of consecutive mCRPC patients with cardiac disorders/risk factors who had been treated with abiraterone 1000 mg once daily plus prednisone 5 mg twice daily for a median duration of 16 months at an oncology referral centre between April 2011 and July 2015. Patients underwent an electrocardiogram (ECG) and echocardiographic assessments, including measurement of left ventricular ejection fraction (LVEF) at baseline and at the end of treatment. Blood pressure (BP) was measured daily at home. During follow up (median 24 months), all adverse events were recorded. Cardiac events (CEs) were defined, according to Common Terminology Criteria for Adverse Events version 4.0, as the appearance of a symptomatic CE that required medical intervention. Results: A total of 51 patients (median age 71 years) were evaluated. Pre-existing cardiovascular conditions included hypertension (41%), cardiac ischaemia (12%), stroke (9%), dyslipidaemia (18%) and type 2 diabetes mellitus (12%). No CEs were recorded and no changes in LVEF were observed. The most frequently reported adverse events were Grade 1-2 fluid retention (18%), hypertension (16%) and asthenia (16%). No patients permanently discontinued abiraterone due to cardiac events. Conclusions: Long-term abiraterone treatment was well tolerated in mCRPC patients with controlled cardiovascular comorbidities/risk factors, with no apparent worsening of cardiovascular conditions from baseline over an extended observation period.