Effects of apalutamide dose reduction on skin‐related adverse events in patients with advanced prostate cancer: A multicenter retrospective study

We aimed to evaluate the effects of apalutamide dose reduction on skin-related adverse events (AEs) and castration-resistant prostate cancer (CRPC)-free survival in patients with advanced prostate cancer (PC).We retrospectively evaluated 35 patients with nonmetastatic CRPC and 72 patients with treatment-naïve metastatic castration-sensitive PC (mCSPC) who were treated with apalutamide. The primary outcome was the effect of apalutamide dose reduction on skin-related AEs. The secondary outcomes were the effect of apalutamide dose reduction on skin-related AEs in patients with small body size, postskin AE apalutamide discontinuation rate, and CRPC-free survival in patients with mCSPC treated with upfront apalutamide plus androgen deprivation therapy.Of the 107 patients, 65 (60.7%) and 42 (39.3%) were treated with full and reduced doses of apalutamide, respectively. The skin-related AE rate was not significantly different between the groups (55% vs. 43%, p = 0.761). In the group receiving reduced apalutamide dose, the incidence of skin-related AEs was significantly lower in patients with small body sizes (body weight <67 kg and body mass index <24 kg/m2 ) than in those with other body sizes. The postskin AE apalutamide discontinuation rate was significantly differed between patients receiving the full (50%) and reduced (16.7%) doses. In the 72 patients with mCSPC, CRPC-free survival was not significantly different between the full and reduced dose groups.Apalutamide dose reduction was not significantly associated with the incidence of skin-related AEs. However, dose reduction in patients with small body sizes may alleviate skin-related AEs without sacrificing oncological outcomes.