Takashi Kobayashi1, Naoki Terada2, Takahiro Kimura3, Nobuaki Matsubara4, Kaoru Murakami1, Keiichiro Mori3, Yumi Fujimoto4, Shusuke Akamatsu1, Takahiro Inoue1, Osamu Ogawa5. 1. Department of Urology, Kyoto University Graduate School of Medicine, Kyoto, Japan. 2. Department of Urology, Miyazaki University, Miyazaki, Japan. 3. Department of Urology, Jikei University School of Medicine, Tokyo, Japan. 4. Department of Breast and Medical Oncology, National Cancer Center Hospital East, Chiba, Japan. 5. Department of Urology, Kyoto University Graduate School of Medicine, Kyoto, Japan. Electronic address: ogawao@kuhp.kuoyo-u.ac.jp.
Abstract
BACKGROUND: There has been no established clinical evidence for using sequential treatment in castration-resistant prostate cancer (CRPC). Despite evident cross-resistance, androgen receptor axis-targeted agents (ARTAs), namely abiraterone (ABI) and enzalutamide (ENZ), are often used sequentially owing to less toxicity compared with chemotherapy. PATIENTS AND METHODS: A multicenter retrospective review of chemotherapy-naive patients with CRPC who had received ABI followed by ENZ (ABI-to-ENZ) or ENZ followed by ABI (ENZ-to-ABI) was conducted. Combined progression-free survival (PFS), overall survival (OS), and prostate-specific antigen (PSA) response (≥ 50% PSA decline) to each drug were compared between the 2 groups at the median follow-up of 36.0 months. RESULTS: There were no significant differences in combined PFS (12.4 vs. 10.9 months; hazard ratio [HR], 0.94; 95% confidence interval [CI], 0.72-1.23; P = .6594) or OS (28.3 vs 29.3 months; HR, 0.96; 95% CI, 0.66-1.38; P = .8314) between the ABI-to-ENZ and ENZ-to-ABI groups. PSA response rate was not significantly different in first-line ARTAs (48.9% vs. 58.4%; P = .153) but significantly higher in ENZ as a second-line ARTA (40.4% vs. 13.7%; P < .0001). Although multivariate analysis revealed that the ABI-to-ENZ sequence was associated with favorable PFS on second-line ARTA (HR, 0.65; 95% CI, 0.49-0.85; P = .0019), it was not associated with an increased combined PFS or OS. CONCLUSION: With relatively longer follow-up, ARTA sequence did not affect clinical outcomes of CRPC treatment except for PSA response and PFS on a second-line ARTA. These findings will be useful information in clinical decision-making, particularly in chemotherapy-unfit patients with CRPC.
BACKGROUND: There has been no established clinical evidence for using sequential treatment in castration-resistant prostate cancer (CRPC). Despite evident cross-resistance, androgen receptor axis-targeted agents (ARTAs), namely abiraterone (ABI) and enzalutamide (ENZ), are often used sequentially owing to less toxicity compared with chemotherapy. PATIENTS AND METHODS: A multicenter retrospective review of chemotherapy-naive patients with CRPC who had received ABI followed by ENZ (ABI-to-ENZ) or ENZ followed by ABI (ENZ-to-ABI) was conducted. Combined progression-free survival (PFS), overall survival (OS), and prostate-specific antigen (PSA) response (≥ 50% PSA decline) to each drug were compared between the 2 groups at the median follow-up of 36.0 months. RESULTS: There were no significant differences in combined PFS (12.4 vs. 10.9 months; hazard ratio [HR], 0.94; 95% confidence interval [CI], 0.72-1.23; P = .6594) or OS (28.3 vs 29.3 months; HR, 0.96; 95% CI, 0.66-1.38; P = .8314) between the ABI-to-ENZ and ENZ-to-ABI groups. PSA response rate was not significantly different in first-line ARTAs (48.9% vs. 58.4%; P = .153) but significantly higher in ENZ as a second-line ARTA (40.4% vs. 13.7%; P < .0001). Although multivariate analysis revealed that the ABI-to-ENZ sequence was associated with favorable PFS on second-line ARTA (HR, 0.65; 95% CI, 0.49-0.85; P = .0019), it was not associated with an increased combined PFS or OS. CONCLUSION: With relatively longer follow-up, ARTA sequence did not affect clinical outcomes of CRPC treatment except for PSA response and PFS on a second-line ARTA. These findings will be useful information in clinical decision-making, particularly in chemotherapy-unfit patients with CRPC.