Posted: Friday, March 31, 2023
Reportedly the first study of alternating administration of bipolar androgen therapy and novel androgen receptor–targeted therapy is underway in Brazil; the phase II single-arm Ex-BAT (LACOG 0620) trial will ultimately include 47 patients with metastatic castration-resistant prostate cancer. Pedro H. Isaacsson Velho, MD, of Hospital Moinhos de Vento, Porto Alegre, and colleagues have coined the strategy "extreme bipolar androgen therapy" and described the multicenter trial in progress during the 2023 American Society of Clinical Oncology (ASCO) Genitourinary (GU) Cancers Symposium (Abstract TPS276).
All included patients experienced disease progression on abiraterone by Prostate Cancer Clinical Trials Working Group 3 criteria, explained the team. The patients are receiving intramuscular testosterone cypionate at 400 mg on day 1, followed by oral darolutamide at 1,200 mg/day for 4 weeks (starting on day 29 through day 56) on 63-day cycles.
The primary endpoint is radiographic progression–free survival at 12 months; secondary endpoints include prostate-specific antigen decline rates, overall survival, toxicity, quality of life, and predictive biomarkers of response and survival. Tumor assessments will be performed every 9 weeks for the first two cycles and every 18 weeks thereafter, for up to 12 months. Patients are allowed to have had prior docetaxel for metastatic hormone-sensitive disease if 12 or more months have elapsed from the last dose.
Multiple previous early-phase trials, Dr. Isaacsson Velho and co-investigators noted, have shown that bipolar androgen therapy, defined as exogenous supraphysiologic doses of testosterone followed by castrate levels, is clinically active and may improve quality of life for this patient population. Castration-resistant prostate cancer develops, almost invariably, after patients with advanced or metastatic disease develop resistance to androgen-deprivation therapy.
In the ExBAT trial, patients with disease progression who experience a clinical benefit will be allowed to continue treatment. Also, patients without disease progression after 12 months will be permitted to receive the study treatment in an extension phase.
Disclosure: The study authors’ disclosure information can be found at coi.asco.org.