Castration-resistant prostate cancer (CRPC)-free survival among men who experience biochemical failure following radical prostatectomy (RP) is closely correlated with metastasis-free survival (MFS), suggesting that the former could serve as an intermediate endpoint in clinical trials, investigators concluded in a poster presentation during the European Society for Medical Oncology (ESMO) Virtual Congress 2020.
MFS is a surrogate for overall survival in men with localized prostate cancer, but this endpoint may take years to develop in patients with nonmetastatic castration-sensitive disease, a team co-led by Stephen J. Freedland, MD, of Cedars-Sinai Medical Center in Los Angeles, California, and Durham VA Medical Center in Durham, North Carolina, and Zachary Klaassen, MD, of Augusta University in Augusta, Georgia, explained. “Other evidence-based intermediates that occur earlier in the disease course are needed for clinical trial design to expedite evaluating new therapies,” they noted.
Drs Freedland and Klaassen and their colleagues conducted a retrospective cohort study that included 210 men who had biochemically recurrent PCa after RP, a PSA doubling time of less than 9 months, and no evidence of metastasis at the time of starting androgen deprivation therapy (ADT). The primary outcome was the correlation between CRPC-free survival (CRPC-FS) and MFS.
The median pre-ADT PSA level was 3.8 ng/mL. During a median follow-up of 79.4 months after initiation of ADT, CRPC or death occurred in 131 patients and metastasis developed in 132 patients. The median CRPC-FS and MFS was 100 months and 104 months, respectively. When limited to men with a PSA at ADT initiation greater than 1 ng/mL and those with a Charlson Comorbidity Index of 2 or less, there was an approximately 85% and 88% correlation between CRPC-FS and MFS, respectively, and 76% and 74% correlation between time to CRPC and time to metastasis, respectively.
Node-positive disease and higher PSA at ADT initiation similarly predicted time from ADT to CRPC or death and MFS, according to the investigators.
Freedland SJ, Howard L, Wallis CJD, et al. Correlation between castration-resistant prostate cancer (CRPC) free survival (CRPC-FS) and metastasis free survival (MFS) in men initiating androgen deprivation therapy (ADT) for biochemical recurrence (BCR) after radical prostatectomy (RP). Presented at: ESMO Virtual Congress 2020. Abstract 683P.