The value of continuation of androgen deprivation therapy (ADT) 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 (AA), which in combination with prednisone (P), has the ability to further suppress testosterone serum levels over ADT alone, continuation of ADT seems to be negligible. The aim of the SPARE trial was to explore the role of continuation
of ADT upon treatment with AA+P in patients with asymptomatic or mildly symptomatic, chemotherapy-naïve CPRC.
The exploratory phase II trial randomized patients to receive continued ADT versus ADT withdrawal at the time of starting AA+P therapy (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.
Altogether, 67 patients were randomized between 08/2014 to 04/2017.
LHRH+AA+P | AA+P | ||
Patients (n) | 34 | 33 | |
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 serum testosterone level at baseline | 0.08 ng/ml | 0.06 ng/ml | |
Median serum testosterone level at end-of-treatment visit | 0.029 ng/ml | 0.029 ng/ml | |
Median treatment duration (d) |
266 | 420 | HR 1.667 (p=0.197)* |
Time to PSA progression (d) | 288 | 336 | HR 1.733 (p=0.188)* |
Rate of rPFS at month 12 | 0.90 | 0.78 | p=0.4368* |
*study was not powered for a direct comparison between treatment arms
The results of the exploratory study show treatment with AA + P without ADT is efficient and comparable to the results of the COU-AA-302 trial. According to these results, continuation of ADT may not be necessary in combination with AA + P in patients with mCRPC.