Adding an anti-androgen such as bicalutamide or flutamide to androgen deprivation therapy (ADT) for metastatic castration-sensitive prostate cancer (mCSPC) does not improve outcomes compared with ADT alone, according to an analysis of real-world evidence presented at the virtual 2021 Genitourinary Cancers Symposium.
In a retrospective study of data from the Veterans Health Administration database, a team led by Stephen J. Freedland, MD, of Cedars-Sinai Medical Center in Los Angeles, California, and the Durham VA Medical Center in Durham, North Carolina, found that ADT plus an anti-androgen and ADT alone were associated with a similar time to development of castration-resistant disease (21.4 vs 22.5 months). Both treatments also were associated with a similar death risk, with median overall survival not reached in either study arm.
In an interview with Renal & Urology News, Dr Freedland noted that older data suggested that adding an anti-androgen to ADT improved survival, albeit modestly. It remains unclear, however, whether their results suggest a true lack of benefit from this combination or reflect that men with more aggressive disease are more commonly treated with anti-androgens, as they were unable to adjust for this potential confounder.
Still, the study suggests no benefit from adding an anti-androgen to ADT. Importantly, Dr Freedland said, the novel hormonal therapies enzalutamide, apalutamide, abiraterone, and docetaxel do offer a significant survival advantage and should be the drugs of choice to add to ADT for mCSPC.
The study included 1395 patients with mCSPC who initiated treatment from 2014 to 2018: 874 treated with ADT alone; 338 treated with ADT plus an anti-androgen; 75 who received ADT plus abiraterone; and 108 who received ADT plus docetaxel.
Dr Freedland and his colleagues pointed out in their poster presentation that the median time to castration-resistant disease and risk of death observed in their study for both ADT plus an anti-androgen and ADT alone were similar to published data from corresponding placebo arms in clinical trials of novel hormonal therapies, such as STAMPEDE and LATITUDE, but inferior to outcomes in the treated arms of these trials, “indicating significant room for survival improvement in the mCSPC population.”
Disclosure: Pfizer Inc and Astellas Pharma Inc. funded the study. See the study poster for a list of author disclosures.
Freedland SJ, Sandin R, Sah J, et al. Survival outcomes in patients with metastatic castration-sensitive prostate cancer (mCSPC): a real-world evidence study. Presented at the virtual 2021 Genitourinary Cancers Symposium, February 11 to 13. Poster 46.