Use of Abiraterone And Enzalutamide In Metastatic Castration-Resistant Prostate Cancer In Routine Clinical Practice

OBJECTIVES: To describe the results of abiraterone (AB) and enzalutamide (ENZ) treatment for metastatic Castration-Resistant Prostate cancer (mCRPC), the medication adherence and the monthly cost per patient. METHODS: Prospective, descriptive, real world data based study including patients with mCRPC treated with abiraterone or enzalutamide. Initial registered variables: ECOG, Gleason, PSA levels. Follow-up variables: response evaluation criteria (RECIST), PSA levels, discontinuation and reason of discontinuation (progression, death, worst ECOG status, unacceptable toxicity, lack of adherence, patient decision, loss of follow-up). The number and cost of monthly dispensed containers was registered for each patient. All the data was extracted from the clinical practice registries: RPT-SAP® and Silicon®. The statistical data was obtained from SPSS® program. RESULTS: A total of 37 patients were included: 17 of them received abiraterone and 20 enzalutamide. Nineteen have previously been treated with docetaxel (7 of AB and 12 of ENZ). Five of the 17 patients treated with abiraterone (29,4%) stopped the treatment. The reasons were: progression (100%) and worst ECOG status (40%). On the enzalutamide group, 9 of the 20 patients (45%) stopped the treatment because of: progression (88%), worst ECOG status (33%) and death (11%). The median of progression-free survival (PFS) for all the patients treated with abiraterone or enzalutamide was 20 months and the PFS after a year of treatment was 61%. No difference was found between drugs in monthly cost per patient: 3142±432f (AB) and 3013±794€ (ENZ). The number of containers monthly dispensed per patient was: 1.12*0.17 (AB) and 1.18±0.28 (ENZ). CONCLUSIONS: Median PFS is slightly superior to which was found in clinical trials and medication adherence was excellent. Limitations of the study are: lack of data on concomitant treatments, adverse effects and patient related outcomes.