(UroToday.com) The 2023 AUA annual meeting included an advanced prostate cancer session, featuring a presentation by Dr. Kyo Togashi discussing the effect of a reduced dose of apalutamide on skin-related adverse events in advanced prostate cancer. The incidence of skin-related adverse events of apalutamide was higher in Japanese patients (51.47%) than in the phase 3 SPARTAN (23.8%) and TITAN (27.1%) trials.1-3 Additional analyses have suggested that small body size of the Japanese men may result in high levels of apalutamide in the blood. As such, Dr. Togashi and colleagues aimed to evaluate the effect of apalutamide dose reduction on skin-related adverse events and castration-resistant prostate cancer (CRPC)-free survival in patients with advanced prostate cancer.
This study retrospectively evaluated 35 patients with nonmetastatic CRPC and 72 treatment-naïve metastatic castration-sensitive prostate cancer (mCSPC) patients treated with apalutamide. The primary outcome was the effect of apalutamide dose reduction on skin adverse events. The secondary outcomes were the effect of apalutamide dose reduction on skin adverse events in patients with small body size, post-skin adverse event discontinuation rate, and the effect of apalutamide dose reduction on CRPC-free survival in patients with mCSPC treated with upfront apalutamide plus ADT.
Of the 107 patients included in the study, the median age was 73 years, and 65 (60.7%) and 42 (39.3%) were treated with full (240 mg/day) and reduced doses (120 – 180 mg/day) of apalutamide, respectively. As follows are the background characteristics of these patients:
The skin adverse event rate was not significantly different between the groups (55% vs. 43%, p = 0.761):
The incidence rate of skin adverse events in the reduced dose (46%) of apalutamide was significantly lower in patients with small body size (body weight <67 kg and body mass index <24 kg/m2) than in those with other body size (74%, p = 0.032):
The apalutamide discontinuation rate after skin adverse events significantly differed between the full dose (50%) and reduced dose (16.7%) groups. Of the 72 patients with mCSPC, the CRPC-free survival was not significantly different between the full dose and reduced dose groups:
Dr. Togashi concluded his presentation by discussing the effect of a reduced dose of apalutamide on skin-related adverse events in advanced prostate cancer with the following take-home messages:
- Apalutamide dose reduction was not significantly associated with the incidence of skin adverse events
- However, dose reduction for patients with small body size may alleviate skin adverse events without sacrificing oncological outcome
Presented by: Kyo Togashi, MD, Hirosaki University Graduate School of Medicine, Hirosaki, Japan
Written by: Zachary Klaassen, MD, MSc – Urologic Oncologist, Assistant Professor of Urology, Georgia Cancer Center, Augusta University/Medical College of Georgia, @zklaassen_md on Twitter during the 2023 American Urological Association (AUA) Annual Meeting, Chicago, IL, April 27 – May 1, 2023
- Uemura H, et al. BMC Urol. Sep 2 2020;20(1):139
- Smith MR, Saad F, Chowdhury S, et al. Apalutamide treatment and metastasis-free survival in prostate cancer. N Engl J Med 2018;378(15):1408-1418.
- Chi KN, Agarwal N, Bjartell A, et al. Apalutamide for metastatic, castration-sensitive prostate cancer. N Engl J Med 2019 Jul 4;381(1):13-24.