Treatment selection for men with metastatic prostate cancer who progress on upfront chemo-hormonal therapy

Background: Androgen deprivation therapy plus docetaxel (D-ADT) increases overall survival (OS) in men with high-volume, metastatic hormone-sensitive prostate Cancer (mHSPC). Although the vast majority of men initially respond to D-ADT, most will progress and develop castration-resistant prostate Cancer (CRPC). Little is known about the optimal treatment sequence for men with progressive disease on D-ADT.

Patient and methods: Retrospective analysis of consecutive mHSPC patients treated with ≥3 cycles of D-ADT at Cleveland Clinic and University of Wisconsin-Madison was undertaken. The primary end-points included radiographic progression free survival (rPFS) and OS with first-line treatment for metastatic CRPC (mCRPC).

Results: Final analysis included 136 patients, median age 65 (range 35-86), 77% GS ≥ 8, and 79% with high-volume disease who received ≥3 cycles of docetaxel. Undetectable PSA values at 12 and 24 months were observed in 32% and 25% of patients, respectively. Median time to CRPC (biochemical, clinical, or radiographic) was 19.6 months (16.6-22.6). Sixty patients (44%) received ≥1 treatment for CRPC: 48 patients (80%) received a second-generation hormonal therapy (sHT). Among these, 22 received abiraterone acetate, 20 enzalutamide, and six a novel CYP-17 inhibitor on trial (ASN-001). Five patients (8%) received sipuleucel-T; four (7%) radium-223, five (8%) chemotherapy (two carboplatin-based, two single agent cabazitaxel, one single agent docetaxel) and three other. Patients receiving sHT as the first treatment for mCRPC had a median rPFS of 9.0 months (95%CI, 6.9-11.2) compared with 3.0 months (95%CI, 1.5-4.5) for patients who received a non-sHT (P = 0.024). The choice of first therapy for mCRPC was independent of GS (P = 0.909), visceral disease (P = 0.690) and time to CRPC (P = 0.844). Longer OS correlated with time to CRPC (P = 0.010) and first treatment for CRPC with sHT (P = 0.005).

Conclusions: For patients with progressive disease on D-ADT, subsequent treatment with a sHT is associated with a longer rPFS and OS.

chemo-hormonal therapy; docetaxel; hormone-sensitive prostate cancer; second-generation hormonal therapy; subsequent therapies.