Real-World Prostate-Specific Antigen Response and Treatment Adherence of Apalutamide in Patients With Non-Metastatic Castration-Resistant Prostate Cancer

Abstract

Objective

To describe prostate-specific antigen (PSA) response and treatment adherence, overall and stratified by race, for patients with non-metastatic castration-resistant prostate cancer (nmCRPC) treated with apalutamide.

Methods

Electronic medical records representing 63 urology practices from the United States were used to conduct this study. Patients with ≥2 apalutamide prescription fills and ≥12 months of prior prostate cancer management were identified. Patients were followed from apalutamide initiation until a switch to another antineoplastic treatment, death, or end of data availability (October 4, 2019). PSA response (≥50% decline from baseline PSA) and apalutamide adherence rates are described for the overall nmCRPC population treated and also stratified by race (Black and non-Black cohorts).

Results

Overall, 193 patients with nmCRPC were initiated on apalutamide. Thirty-three patients were Black (17.1%), 138 were non-Black (71.5%), and the remaining had an unknown racial background. The mean baseline PSA level for the overall, Black, and non-Black cohorts, was 7.0 ng/mL, 10.5 ng/mL, and 5.6 ng/mL, respectively. At 12 months of follow-up, PSA response was 86.0%, 93.1%, and 85.9% for the overall, Black, and non-Black cohorts, respectively. During a mean follow-up period of 333 days, 352 days, and 326 days, adherence was 93.6%, 90.1%, and 94.5% for the overall, Black and non-Black cohorts, respectively.

Conclusion

This real-world study of patients with nmCRPC initiated on apalutamide showed that PSA response was robust and consistent with clinical trial data. Moreover, both Black and non-Black patients demonstrated high treatment adherence.