Real-world effectiveness and treatment adherence with apalutamide in nmCRPC

Judd W. Moul, MD, discusses data from the following presentation:

Real-world effectiveness and treatment adherence of apalutamide in patients with nonmetastatic castration-resistant prostate cancer that were presented at the American Urological Association 2021 Annual Meeting (Lowentritt B et al, AUA 2021; September 10-13, 2021)

• Real-world evidence on apalutamide, which was recently approved to treat patients with nonmetastatic castration-resistant prostate cancer (nmCRPC), is limited in the United States. This study describes prostate-specific antigen (PSA) response and treatment adherence among patients with nmCRPC treated with apalutamide, with stratification by Black and non-Black patients.
• Electronic medical records of 63 US urology practices were obtained and used to conduct this retrospective study of patients with nmCRPC who received apalutamide on or after February 14, 2018 (index date). Included patients had at least 2 apalutamide prescription fills and at least 12 months of prior prostate cancer management (baseline period). Patients were followed from the index date until a switch to another antineoplastic treatment, death, or end of data (October 4, 2019).
• PSA response (≥50% decline from baseline PSA) and apalutamide adherence rates, measured by the medication possession ratio (total days of medication supplied relative to the time between the initiation and the end of the last prescription filled), were described for the overall population and also stratified by Black and non-Black cohorts.
• Overall, 193 patients with nmCRPC were initiated on apalutamide (33 were Black [17%], 138 were non-Black [72%], and 22 had an unknown racial background [11%]). Most patients (146 patients; 76%) were between 71 and 90 years.
• Real-world effectiveness results:
  • The mean baseline PSA level for the overall, Black, and non-Black cohorts was 7.0, 10.5, and 5.6 ng/mL, respectively (evaluated on 190, 33, and 135 patients).
  • Among patients with at least 3 baseline PSA tests, median baseline PSA doubling time was 8.5, 7.3, and 8.4 months for the overall, Black, and non-Black cohorts, respectively (evaluated on 90, 16, and 70 patients).
  • At 12 months’ follow-up, PSA response to APA was 86%, 93%, and 86% for the overall, Black, and non-Black cohorts among patients with both pre- and postindex PSA measurements, respectively (evaluated on 178, 29, and 128 patients).
• Adherence results:
  • During a mean follow-up period of 11.0, 11.6, and 10.7 months, apalutamide adherence was 93.6%, 90.1%, and 94.5% for the overall, Black, and non-Black cohorts, respectively.
• This real-world study of patients with nmCRPC initiated on apalutamide demonstrated good adherence to medication and robust PSA response consistent with the results from a prior published clinical trial. Moreover, these responses were observed in both Black and non-Black patients.