Planned interim analysis of perioperative safety of fluzoparib combined with abiraterone in the neoadjuvant treatment of locoregional high-risk prostate cancer: Results from multicenter, phase 2 FAST-PC trial.

356 Background: Previous studies confirmed that the combination of PARP inhibitors and abiraterone might bring survival benefits to prostate cancer (PC) patients (pts) regardless of HRR mutation status. Hence, we conducted a single-arm, multicenter, phase II trial (FAST-PC, NCT05223582) to investigate safety and efficacy of fluzoparib combined with abiraterone and androgen deprivation therapy (ADT) in the neoadjuvant treatment of locoregional high-risk PC. Herein, a planned interim analysis of safety outcome of this study was reported. Methods: FAST-PC trial enrolled pts with only pelvic lymph node metastasis or high-risk localized (cT3-4 or prostate specific antigen (PSA) >20 ng/mL or Grade Group ≥4) PC. Eligible pts received fluzoparib (150mg PO BID), abiraterone (1000mg PO QD), prednisone (5mg PO BID), and ADT for 24 weeks followed by minimally invasive radical prostatectomy (RP). Perioperative outcomes were collected and evaluated during treatment period and follow-up period which was three months after surgery. Post-surgery AEs within 90 days were classified by Clavien-Dindo. Results: As of Sep 2022, 31 pts were recruited. All the 12 pts (patient No.1 to No.12) who have completed both the 24-week neoadjuvant regimen and surgery were analyzed. Baseline characteristics were shown in table. None of them were lost to follow-up or discontinued the protocol due to adverse events (AEs). The common AEs related to medication including anemia (4, 33.3%), hypokalemia (3, 25.0%), and liver dysfunction (3, 25.0%). As for post-surgery outcomes, median days of hospitalization, surgical time, and blood loss were 8.5 days (6-12.8), 144 minutes (16.5-171.3), and 100ml (50-200), respectively. Overall, 7 (58.3%) pts experienced post-surgery AEs of any grade, in which 4 (33.3%) were grade 1 and 3 (25.0%) were grade 2. 6 (50.0%) experienced fever, and 2 (16.7%) had urinary tract infections. Of note, pulmonary thrombosis (grade 2) was diagnosed in one patient after RP. Conclusions: Our data represent the first prospective evidence supporting the perioperative safety in locoregional high-risk PC pts who received neoadjuvant fluzoparib combined with abiraterone and ADT. The combined regimen is generally safe and reliable, while special vigilance should be paid to the occurrence of anemia, hypokalemia and liver dysfunction. Clinical trial information: NCT05223582 . [Table: see text]