The value of continuation of luteinizing hormone-releasing hormone (LHRH) therapy in 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, which in combination with prednisone, has the ability to further suppress testosterone serum levels over LHRH therapy alone, continuation of LHRH therapy seems to be negligible. The aim of the SPARE trial therefore was to explore the role of continuation of LHRH therapy when starting treatment with abiraterone acetate plus prednisone (AA+P) in patients with asymptomatic or mildly symptomatic, chemotherapy-naïve CPRC.
Patients were randomized to receive continuing LHRH therapy versus LHRH withdrawal at the time of starting abiraterone AA+P therapy (NCT02077634). The primary endpoint was rate of rPFS at month 12. Secondary endpoints included PSA response rate, objective response, time to PSA progression and safety.
Altogether, 68 patients were randomized. Median age was 75 (60-86) years with a median PSA at baseline of 23.9 (0.17-1680) ng/ml. Results of the secondary endpoints were evaluated.Table: 810P
|Median age (range)||74 (60-86) years||76 (60-86) years|
|Median baseline PSA (range)||31.9 (0.17-313.2) ng/ml||20.59 (1.97-1680) ng/ml|
|PSA-decline ≥50%||23/34 (67.6%)||24/33 (72.7%)|
|Median treatment duration (d)||266||420||1.667 (0.197)*|
|Time to PSA progression (d)||288||336||1.733 (0.188)*|
study was not powered for these endpoints.
The results of the exploratory study show that AA + P without continuation of LHRH therapy leads to considerable PSA response rates and longer time to PSA progression. The currently assessed efficacy is comparable to the results of the COU-AA-302 trial, hypothesising that continuation of LHRH therapy may not be necessary upon treatment with AA + P. Results on the primary endpoint and the safety profile are pending and are currently being evaluated.
Clinical trial identification
Legal entity responsible for the study
C. Ohlmann: Research funding: Janssen-Cilag. All other authors have declared no conflicts of interest.