Neoadjuvant radiohormonal therapy for oligo-metastatic prostate cancer: safety and efficacy outcomes from an open-label, dose-escalation, single-center, phase I/II clinical trial

To evaluate the safety and efficacy of neoadjuvant radiohormonal therapy for oligometastatic prostate cancer (OMPC), we conducted a 3 + 3 dose escalation, prospective, phase I/II, single-arm clinical trial (CHiCTR1900025743), in which long-term neoadjuvant androgen deprivation was adopted 1 month before radiotherapy, comprising intensity modulated radiotherapy to the pelvis, and stereotactic body radiation therapy to all extra-pelvic bone metastases for 4-7 weeks, at 39.6, 45, 50.4, and 54 Gy. Robotic-assisted radical prostatectomy was performed after 5-14 weeks. The primary outcome was treatment-related toxicities and adverse events; secondary outcomes were radiological treatment response, positive surgical margin (pSM), postoperative prostate-specific antigen (PSA), pathological down-grading and tumor regression grade, and survival parameters. Twelve patients were recruited from March 2019 to February 2020, aging 66.2 years in average (range, 52-80). Median baseline PSA was 62.0 ng/mL. All underwent RARP successfully without open conversions. Ten patients recorded pathological tumor down-staging (83.3%), and 5 (41.7%) with cN1 recorded negative regional lymph nodes on final pathology. 66.7% (8/12) recorded tumor regression grading (TRG) -I and 25% (3/12) recorded TRG-II. Median follow-up was 16.5 months. Mean radiological progression-free survival (RPFS) was 21.3 months, with 2-year RPFS of 83.3%. In all, neoadjuvant radiohormonal therapy is well tolerated for oligometastatic prostate cancer.