e17571 Background: Abiraterone acetate and prednisolone (AAP) + ADT has been approved for treatment metastatic castration-resistant prostate cancer (CRPC) in the standard dose 1,000 mg with fasting state. Data in Ramathibodi hospital showed patients who had treated with standard dose of Abiraterone acetate (AA); had PSA response 47.83%. Previous studies showed using low dose AA of 250 mg with food had the non-inferiority results in efficacy. AA was not be reimbursed in Thailand, so the ability to use a highly effective drug at a quarter of the dose, could help in patient accessibility to cancer treatments. We sought to test the hypothesis that low-dose AA with food would have the comparable activity in Thai CRPC patients in both of the pre-Docetaxel and post Docetaxel treatment groups, and exploring the quality of life (QOL) of these patients. Methods: An observational cohort enrolled newly diagnosed metastasis CRPC at Ramathibodi hospital from 1st Jan 2019 to 31st Dec 2019. Patients were assigned to AA (250mg) with actual daily life meal. We collected the data of serum PSA and the adverse events every 4 weeks for 4 months. The QOL data was collected with the EuroQoL (EQ-5D) questionnaire which were done at baseline and every 4 weeks. The primary end point was PSA response that defined as PSA decreased ≥ 50% from PSA level at baseline. The secondary endpoint were the depth of PSA change, QOL and adverse events by using Fisher's exact test and T-test. Results: 21 patients were enrolled. At 12 weeks, there were 11 patients (52.38%) achieved 50% PSA response and 6 patients (28.57%) achieved 90% PSA response. The adverse events occurred 23.8%, and mostly were mild grade. The adverse events were comparable with the historical data in standard dose of AA. Low dose AA has significantly shown the improvement in quality of life from baseline (p < 0.001), and especially the significant improvement in pre-Docetaxel subgroup. Conclusions: Low-dose AA with food has good efficacy in PSA response, adverse events and QOL. Moreover, low dose AA shows more efficacy especially in pre-Docetaxel mCRPC patients. Low dose AA may be helping in reducing cost of cancer care, enabling in delivering affordable cancer care and increasing value of treatment.
Low Incidence of Corticosteroid-associated Adverse Events on Long-term Exposure to Low-dose Prednisone Given with Abiraterone Acetate to Patients with Metastatic Castration-resistant Prostate Cancer
