Abstract 348P
Background
Elderly CRPC patients are hardly focused by clinical trials, and data regarding outcomes of second generation androgen receptor signaling inhibitors (ARSIs) is limited.
Methods
The ENABLE study for PCa, an investigator-initiated, multicenter, randomized controlled trial comparing between enzalutamide (ENZ) and abiraterone plus prednisolone (ABI) was conducted in Japan. We analyzed the efficacy of these ARSIs for older (75 years or older) patients. Prespecified survival endpoints and safety profiles were compared between older and younger (<75 years) patients and between ENZ and ABI in older patients.
Results
The number of younger and older patients was 41 and 51 in the ENZ arm and 36 and 56 in the ABI arm, respectively. Median time to PSA progression (TTPP) of younger and older patients was 15.2 and 21.2 months (HR 0.84, 95%CI 0.53-1.33, P=0.4647) and median overall survival (OS) of them was 33.7 and 37.8 months (HR 0.80, 95%CI 0.50-1.29, P=0.3651), respectively. Among 107 older patients, TTPP of the ENZ and ABI arm was 21.2 and 10.1 months (HR 0.65, 95%CI 0.36-1.17, P=0.1506) and OS of them was 37.8 and 44.7 months (HR 0.97, 95%CI 0.51-1.84, P=0.9321), respectively. However, the ENZ arm showed better percentage of PSA response rate than the ABI arm (75% vs 53%, P=0.0421). Similar adverse event rates and grades were observed in younger and older patients.
Conclusions
ARSIs showed similar efficacy and safety profiles in younger and older patients. ENZ may be a better choice for older patients with favorable PSA response rate.
Clinical trial identification
UMIN000015529.
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
The Japanese Foundation for Multidisciplinary Treatment of Cancer.
Disclosure
All authors have declared no conflicts of interest.