Reduced-Dose ARPI Treatment Inferior for Castration-Resistant Prostate Cancer

Outcomes were worse in patients with chemotherapy-naïve castration-resistant prostate cancer (CRPC) who received reduced-dose androgen receptor pathway inhibitor (APRI) treatment compared with standard-dose treatment, according to a study published in Prostate International.

“Therefore, full-dose administration of ARPI for CRPC may be appropriate, if physiologically and economically feasible,” advised researchers from Kyushu University Hospital and Harasanshin Hospital in Japan.

The study focused on 162 men treated with ARPI as first-line treatment for CRPC: 57 received abiraterone and 105 received enzalutamide. During treatment, 20.4% of patients had their ARPI dose reduced. Older age, higher prostate-specific antigen level, and enzalutamide were associated with dose reduction.

Reduced-dose enzalutamide was particularly associated with shorter progression-free survival. In the reduced-dose group, the median progression-free survival was 7.2 months compared with 12.1 months for standard-dose group, according to the study. The trend was similar for overall survival, although statistical significance was not reached.

On the whole, associations between dose reduction and decreased progression-free and overall survival were consistent for both abiraterone and enzalutamide, researchers reported.

“Taken together,” they wrote, “these findings suggest that dose reduction of ARPI, mainly enzalutamide, may lead to a reduction in its anticancer effect, resulting in a poor oncological outcome.”

Reference:
Yamada S, Shiota M, Blas L, et al. Prognostic impact of dose reduction in androgen receptor pathway inhibitors for castration-resistant prostate cancer. Prostate Int. 2022;10(1):50-55. doi:10.1016/j.prnil.2021.10.001