Background Abiraterone acetate (AB) and enzalutamide (EZ) are two agents involved in the inhibition of androgen biosynthesis by blocking androgen receptors, and are used to treat prostate adenocarcinoma (AP) in castration resistant patients before and after progression to docetaxel.

Purpose To study the effectiveness and safety of AB and EZ as secondline treatmens after docetaxel in patients with unresectable castration resistant AP resistant to docetaxel.

Material and methods Retrospective, observational and analytic study of the treatment of patients with unresectable castration resistant AP that have progressed from a prior treatment with docetaxel in a tertiary hospital.

A period of 21 months was considered (January 2014 to September 2015).

Patient data were obtained from the oncology patients database (Oncobass v10.1) and the electronic health record database (Mambrino XXI).

Demographic data (gender/age) and clinical data (previous and current treatment) were considered for the analysis.

Evolution of prostate specific antigen (PSA) was considered to evaluate the rate of response (lack of response, PSA progression at a rate >0.35 ng/ml growth and response maintenance or PSA decline).

For the safety analysis we considered values of creatinine (Cr), GGT/ALT/AST and clinical feedback to assess the incidence and severity of adverse events (AEs). Data were collected in Excel 2003 and analysed with matrix SPSS v21, drawing comparisons with χ² contingency tables by drug dealing and drug response AEs.

Results We evaluated 42 patients, mean age 74.02 ± 7.09 years; 20 (47.61%) receiving EZ and 22 (52.39%) receibing AB.

The statistical analysis showed no significant difference in efficacy between the lack of EZ (3 (15.00%)) and AB (8 (36.36%)), although there was a trend towards a better response with EZ (p = 0.116).

Regarding safety, 30% (6) of treated patients experienced some AEs. For EZ myopathies and tingling were the most  frequent (3 (50%)). AB patients showed no AEs, and there was a clear tendency for AB to be best tolerated than EZ  (p = 0.006).

Conclusion EZ and AB treatment appeared to be effective in our cohort of patients with castration resistant AP progression after docetaxel, with a tendency for greater efficacy with EZ, but with a slightly higher profile for side effects compared with AB. It is therefore necessary to assess the risk of particular benefit in patients.

No conflict of interest.