Abiraterone acetate plus prednisone (AA+P) without continuing LHRH-therapy in patients with metastatic chemotherapy: Naive castrations-resistant prostate cancer—Results from the SPARE-trial (NCT02077634).

Abstract

5046 Background: The value of continuation of androgen deprivation therapy (ADT) in metastatic castration-resistant prostate cancer (CRPC) remains controversial and clear evidence is lacking. Especially upon treatment with the life-prolonging cytochrome P450 17-alpha-hydroxylase/C17,20 lyase (Cyp17)-inhibitor, abiraterone acetate (AA), which in combination with prednisone (P), has the ability to further suppress serum testosterone levels over ADT alone, continuation of ADT seems to be negligible. Methods: The exploratory phase II trial randomized CRPC patients to receive continued ADT plus AA+P versus AA+P alone (NCT02077634), funded by Jansen-Cilag GmbH, Germany. The primary endpoint was rate of rPFS at month 12, not powered for a direct comparison between treatment arms. Secondary endpoints included PSA response rate, objective response, time to PSA progression and safety. Results: Altogether, 67 patients were randomized between 08/2014 to 04/2017. Median testosterone-levels (T) remained far below castrate-levels throughout treatment in all patients. However, in 6 patients (18%) from Arm B, T-levels increased above castrate levels within 28 days after cessation of AA+P treatment. Median treatment duration is shorter in Arm A. Safety analysis is underway and results will be presented. Conclusions: Results of this exploratory study suggest that treatment with AA+P without ADT may be effective in patients with mCRPC and that ADT may not be necessary in patients receiving AA+P. In some patients, serum-testosterone levels may rise rapidly upon treatment discontinuation so that the levels should be monitored closely. Clinical trial information: NCT02077634. [Table: see text]