INSTITUTIONAL PROTOCOL OF LOW DOSE ABIRATERONE IN METASTATIC CRPC PATIENTS USE IN A PUBLIC BRAZILIAN CENTER INSTITUTION

BACKGROUND Abiraterone acetate (AA) is a potent selective and irreversible inhibitor of CYP17 used as standard treatment for metastatic Castration Resistant Prostate Cancer (mCRPC). In the pivotal trial COU-AA 301, AA 1000 mg/day plus prednisone increased overall survival after docetaxel in patients with mCRPC. A recent trial demonstrated not inferiority in the reduced dose of 250mg/day AA associated with dietary intake, which is described as AA low dose (AALD). OBJECTIVE As an institutional protocol, the main point is to describe a rational use of AALD in a public hospital, in patients with mCRPC exposed to Docetaxel in the first line. METHODS Metastatic CRPC patients with ECOG 0 or 1 who had biochemical progression after docetaxel exposure were submitted to an institutional protocol with AALD plus prednisone. The data was analyzed 4 weeks after the initiation of AALD, being determined the serum level of PSA prior to use of the drug and 04 weeks after. The protocol began in December 2018, being a cut off data population in May 2019. RESULTS The study population consisted of 20 patients included in the institutional protocol. The median serum PSA level after 4 weeks has changed from 77.0mg / dL to 62.25mg / dL, observing a drop of 19.1%. More than 50% PSA reduction was seen in 61.9% of the studied population, 13of20 patients. CONCLUSION Despite the premature data, this study shows PSA reduction with the use of AALD in mCRPC patients. Serum PSA is known as a surrogate end-point for overall survival in those patients. The protocol will for more mature data. In a near future AALD might be an alternative for treating patients in public institutions.