Despite evidence demonstrating an overall survival benefit with up-front hormone therapy in addition to established synergy between hormone therapy and radiation, the addition of metastasis-directed therapy (MDT) to hormone therapy for oligometastatic prostate cancer, to date, has not been evaluated in a randomized clinical trial.
To determine in men with oligometastatic prostate cancer whether the addition of MDT to intermittent hormone therapy improves oncologic outcomes and preserves time with eugonadal testosterone compared with intermittent hormone therapy alone.
The External Beam Radiation to Eliminate Nominal Metastatic Disease (EXTEND) trial is a phase 2, basket randomized clinical trial for multiple solid tumors testing the addition of MDT to standard-of-care systemic therapy. Men aged 18 years or older with oligometastatic prostate cancer who had 5 or fewer metastases and were treated with hormone therapy for 2 or more months were enrolled to the prostate intermittent hormone therapy basket at multicenter tertiary cancer centers from September 2018 to November 2020. The cutoff date for the primary analysis was January 7, 2022.
Patients were randomized 1:1 to MDT, consisting of definitive radiation therapy to all sites of disease and intermittent hormone therapy (combined therapy arm; n = 43) or to hormone therapy only (n = 44). A planned break in hormone therapy occurred 6 months after enrollment, after which hormone therapy was withheld until progression.
The primary end point was disease progression, defined as death or radiographic, clinical, or biochemical progression. A key predefined secondary end point was eugonadal progression-free survival (PFS), defined as the time from achieving a eugonadal testosterone level (≥150 ng/dL; to convert to nanomoles per liter, multiply by 0.0347) until progression. Exploratory measures included quality of life and systemic immune evaluation using flow cytometry and T-cell receptor sequencing.
The study included 87 men (median age, 67 years [IQR, 63-72 years]). Median follow-up was 22.0 months (range, 11.6-39.2 months). Progression-free survival was improved in the combined therapy arm (median not reached) compared with the hormone therapy only arm (median, 15.8 months; 95% CI, 13.6-21.2 months) (hazard ratio, 0.25; 95% CI, 0.12-0.55; P < .001). Eugonadal PFS was also improved with MDT (median not reached) compared with the hormone therapy only (6.1 months; 95% CI, 3.7 months to not estimable) (hazard ratio, 0.32; 95% CI, 0.11-0.91; P = .03). Flow cytometry and T-cell receptor sequencing demonstrated increased markers of T-cell activation, proliferation, and clonal expansion limited to the combined therapy arm.
In this randomized clinical trial, PFS and eugonadal PFS were significantly improved with combination treatment compared with hormone treatment only in men with oligometastatic prostate cancer. Combination of MDT with intermittent hormone therapy may allow for excellent disease control while facilitating prolonged eugonadal testosterone intervals.
ClinicalTrials.gov Identifier: NCT03599765.
JAMA oncology. 2023 Apr 06 [Epub ahead of print]
Chad Tang, Alexander D Sherry, Cara Haymaker, Tharakeswara Bathala, Suyu Liu, Bryan Fellman, Lorenzo Cohen, Ana Aparicio, Amado J Zurita, Alexandre Reuben, Enrica Marmonti, Stephen G Chun, Jay P Reddy, Amol Ghia, Sean McGuire, Eleni Efstathiou, Jennifer Wang, Jianbo Wang, Patrick Pilie, Craig Kovitz, Weiliang Du, Samantha J Simiele, Rachit Kumar, Yerko Borghero, Zheng Shi, Brian Chapin, Daniel Gomez, Ignacio Wistuba, Paul G Corn
Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston., Department of Translational Molecular Pathology, The University of Texas MD Anderson Cancer Center, Houston., Department of Abdominal Imaging, The University of Texas MD Anderson Cancer Center, Houston., Department of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston., Department of Palliative, Rehabilitation and Integrative Medicine, The University of Texas MD Anderson Cancer Center, Houston., Department of Genitourinary Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston., Department of Thoracic/Head and Neck Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston., Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston., Department of Radiation Oncology, Banner MD Anderson Cancer Center, Gilbert, Arizona., Department of Radiation Oncology, The University of Texas Health Science Center at San Antonio., Department of Urology, The University of Texas MD Anderson Cancer Center, Houston., Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York.