Comparing progression following systemic and tumor-directed therapy for <i>de novo</i> versus recurrent PSMA PET–defined oligo-M1 prostate cancer: A pooled analysis of SOLAR and SATURN clinical trials.
Abstract
64 Background: Therapeutic strategies for oligometastatic castration sensitive prostate cancer (omCSPC) combining treatment of the primary and metastases with short-term intensified systemic therapy aim to improve survival and local control while minimizing toxicity from indefinite systemic therapy. This post-hoc analysis of the SOLAR (NCT03298087) and SATURN (NCT03902951) trials, which evaluated systemic and tumor-directed therapy in PSMA-PET defined oligo-M1 (≤5 metastases) de novo and recurrent omCSPC, respectively, aims to draw inferences on biology and oncologic outcome. Methods: All patients were treated with 6 months of systemic therapy: leuprolide, abiraterone acetate with prednisone, and apalutamide in conjunction with SBRT to oligometastatic sites. SOLAR patients were treatment naïve and underwent either radical prostatectomy (RP) with lymph node dissection followed by post-operative radiotherapy for high-risk features, or definitive radiotherapy (dRT). SATURN patients all had recurrent disease after RP with or without postoperative radiotherapy and may have also had prior hormone or metastasis-directed therapy. The primary endpoint (response rate) was the percentage of patients with an undetectable PSA (<0.05 ng/mL) for post-RP patients, or a PSA <2 ng/mL for post-dRT patients, six months after recovery of testosterone to >150 ng/dl. Secondary endpoints included progression-free survival (PFS) and eugonadal PFS starting from time of testosterone recovery. Kaplan-Meier assessed differences in time-to-event endpoints from initiation of systemic therapy. Fischer’s Exact Test compared proportional outcomes. Results: Analysis included data from 24 SOLAR and 26 SATURN patients. Overall, median follow-up was 32 months (interquartile range 28.25-36.75 months). Response rates were higher for de novo versus oligorecurrent patients (20/24 [83%] versus 13/26 [50%], p=0.018). PFS and eugonadal PFS were also significantly longer (median not reached versus 17 months and median not reached versus 13 months, respectively, p<0.05). PFS was shorter for oligorecurrent patients with prior exposure to hormone therapy (median 10 months versus not reached, p<0.05). There was no PFS difference comparing patients treated in the de novo setting versus the recurrent setting who were naive to hormonal therapy (p=0.23). Conclusions: Patients with recurrent omCSPC PSMA-PET defined M1 disease had a worse response rate and shorter PFS following intensified systemic and metastasis-directed SBRT than those with de novo omCSPC. The difference was driven by recurrent patients with prior exposure to hormonal therapy, suggesting a continuum of treatment resistances over repeated courses of hormonal therapy. The majority of patients with de novo omCSPC remain in remission after gonadal recovery. Clinical trial information: NCT03298087 , NCT03902951 .
Article Details
Journal Info
Journal of Clinical Oncology
Lippincott Williams & Wilkins
Authors (20)
Jesus Eduardo Juarez Casillas
Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, CA
John Nikitas
University of California, Department of Radiation Oncology, Los Angeles, CA
Matthew Rettig
Department of Medical Oncology, University of Southern California, Los Angeles, Los Angeles, CA
Robert Evan Reiter
Department of Urology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
Alan Lee
Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, CA
Michael L. Steinberg
Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA
Luca Valle
Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, CA
Tahmineh Romero
Department of Medicine Statistics Core, University of California, Los Angeles, Los Angeles, CA
Jeremie Calais
Luca F. Valle, MD, Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, Radiation Oncology Service, Greater Los Angeles VA Healthcare System, Los Angeles, CA, University of California Los Angeles Jonsson Comprehensive Cancer Center, Los Angeles, CA, Jeremie Calais, MD, PhD, University of California Los Angeles Jonsson Comprehensive Cancer Center, Los Angeles, CA, Department of Nuclear Medicine, University of California Los Angeles, Los Angeles, CA, Amar U. Kishan, MD, Department of Radiation Oncology, University of California Los Angeles, Los Angeles, CA, University of California Los Angeles Jonsson Comprehensive Cancer Center, Los Angeles, CA
Johannes Czernin
Ahmanson Translational Theranostics Division, University of California, Los Angeles, Los Angeles, CA
Sonny Tsai
VA Greater Los Angeles Healthcare System, Los Angeles, CA
Nathanael Kane
Abhishek A Solanki
Loyola University Chicago, Maywood, IL
Rachael Sexton
3Cancer Research and Biostatistics, Seattle, WA
Sai Duriseti
Gholam Reza Berenji
VA Greater Los Angeles Healthcare System, Los Angeles, CA
William Aronson
University of California - Los Angeles, Department of Urology, Los Angeles, CA
Isla Garraway
UCLA David Geffen School of Medicine, Los Angeles, CA
Nicholas George Nickols
Greater Los Angeles Department of Veterans Affairs Healthcare System, Los Angeles, CA
Amar Upadhyaya Kishan
Department of Radiation Oncology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA