Impact of an Early Prostate-Specific Antigen Response on Biochemical Progression during Upfront Androgen Receptor Signal Inhibitor Therapy for Metastatic Hormone-Sensitive Prostate Cancer Available to Purchase

Introduction: We examined the impact of prostate-specific antigen (PSA) response, which is associated with survival, on patients with metastatic hormone-sensitive prostate cancer (mHSPC) treated with androgen receptor signal inhibitors (ARSIs). Methods: We retrospectively reviewed 82 patients with mHSPC who received upfront ARSI treatment. The primary endpoint was PSA progression-free survival (PFS). Patients whose PSA levels decreased to ≤0.2 ng/mL at 3 months after ARSI initiation were classified as deep early, those with >0.2–≤1.0 ng/mL as early, and others as non-PSA responders. Results: The median age of patients was 73 years old, and the median baseline PSA value was 361 ng/mL. Among 82 patients, 32 (39%), 16 (20%), and 34 (41%) were categorized into deep early, early, and non-early PSA responders, respectively. There was a significant association between PSA response status, hemoglobin, and PSA value. During follow-up (median, 23.0 months), 31 (37.8%) patients experienced PSA progression. The PSA progression rates of the deep early, early, and non-early PSA responders were 15.6%, 31.2%, and 61.8% (p < 0.001), and their 2-year PSA PFS rates were 90.5%, 70.7%, and 38.9%, respectively. Conclusion: An early PSA response within 3 months of ARSI initiation was associated with PSA progression in patients with mHSPC.