LHRH sparing therapy in patients with chemotherapy-naïve, mCRPC treated with abiraterone acetate plus prednisone: results of the randomized phase II SPARE trial

Abstract

Background Although the benefit of androgen deprivation therapy (ADT) continuation in metastatic castration-resistant prostate cancer (mCRPC) remains controversial, clinical evidence is lacking. Recent results indicated that treatment with abiraterone acetate (AA) plus prednisone (P) further suppresses serum testosterone levels over ADT alone, suggesting that continuation of ADT in the treatment of mCRPC may not be necessary. Methods In this exploratory phase 2 study, mCRPC patients were randomized with a 1:1 ratio to receive either continued ADT plus AA + P (Arm A) or AA + P alone (Arm B). The primary endpoint was the rate of radiographic progression-free survival (rPFS) at month 12. Secondary endpoints included PSA-response rate, objective response, time to PSA progression and safety. Results A total of 68 patients were equally randomized between the two study arms. Median testosterone-levels remained below castrate-levels throughout treatment in all patients. According to the intention-to-treat analysis the rPFS rate was 0.84 in Arm A and 0.89 in Arm B. Moderate and severe treatment-emergent adverse events were reported for 72% of the patients in Arm A and for 85% of the patients in Arm B. Conclusions AA + P treatment without ADT may be effective in mCRPC patients and ADT may not be necessary in patients receiving AA + P.

Clinical outcomes in patients with metastatic castrate‐resistant prostate cancer treated with abiraterone with or without ongoing androgen deprivation therapy: A retrospective case–control study

“…5,6,10,11 A recently published randomized phase 2 clinical trial (the SPARE study) was conducted to determine the impact of using abiraterone monotherapy without ADT in 34 mCRPC patients. 7 The use of abiraterone alone in that trial resulted in adequate testosterone suppression (to <50 ng/dL), PSA response, and no difference in survival between patients receiving abiraterone alone versus abiraterone plus ADT. 7 Similar outcomes were also observed here.…”

“…7 The use of abiraterone alone in that trial resulted in adequate testosterone suppression (to <50 ng/dL), PSA response, and no difference in survival between patients receiving abiraterone alone versus abiraterone plus ADT. 7 Similar outcomes were also observed here.…”

“…This study (along with the SPARE trial 7 ) may prompt us to consider elderly patients who are opposed to receiving intramuscular/subcutaneous injections, and with low tumor burden, to benefit most from this regimen due to previous studies reporting slow or lack of testosterone recovery time in patients with older age…”

“…Recently, a phase 2 clinical trial was conducted to evaluate the efficacy of single‐agent abiraterone (as a monotherapy, without ADT) in mCRPC patients 7 . Given that this clinical trial suggested that the use of abiraterone with prednisone alone was perhaps as effective as abiraterone with ongoing ADT, we sought to determine the impact of abiraterone monotherapy on clinical outcomes at our institution due to its potential to adequately suppress testosterone levels alone without ADT 8 …”

Reply to RE: Should LHRH therapy be continued in patients receiving Abiraterone Acetate?

“…TO THE EDITOR: Ah-Thiane and Supiot [1] commented on our recent publication about the SPARE-trial [2] and we are grateful for the fruitful comments.…”