Impact of Apalutamide on PSA Response and Disease Progression in nmCRPC

Apalutamide (APA) plus androgen deprivation therapy is a common treatment combination for patients with nonmetastatic castration-resistant prostate cancer (nmCRPC) due to its efficacy in improving metastasis-free survival (MFS). However, limited data are available on how the treatment affects patients with nmCRPC who have already been treated with APA.

Researchers from Chesapeake Urology in Towson, Maryland, conducted a study to determine prostate-specific antigen (PSA) response and MFS in patients with nmCRPC treated with APA and compared their results with the SPARTAN registrational trial, which also analyzed APA in patients with nmCRPC.

Data were collected from 77 different urology practices from February 2017 through April 2022. A total of 406 patients with nmCRPC who had received 1 or more doses of APA were included in the study. The index date was the date of the first dose.

PSA response was monitored while patients received treatment. PSA response was defined as a ≥90% postindex decline (PSA90) in PSA from baseline (using the closest PSA value within 13 weeks prior to or on the index date) and was reported in patients with ≥1 postindex PSA test results by 3 months, 6 months, 12 months, and overall.

Disease progression was evaluated as MFS and defined as the time from index date to the occurrence of metastasis or death. Disease progression was described using Kaplan-Meier (KM) analysis by 6-month increments up to 24 months postindex.

Of the 406 patients included in the study, 96 had available data. The mean and median baseline PSA doubling times were 9.9 months and 7.5 months, respectively. The mean and median treatment durations were 434 days and 305 days, respectively. PSA90 rates were 40% by 3 months, 51% by 6 months, 56% by 12 months, and 58% overall. KM rates for MFS were 95% at 6 months, 90% at 12 months, 82% at 18 months, and 75% at 24 months. Patient PSA response and MFS were consistent with results from the SPARTAN trial.

This study demonstrated the efficacy of APA treatment in patients with nmCRPC, resulting in early PSA responses and MFS similar to the rates seen in the SPARTAN trial.