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

<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>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).</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>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.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>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%, <jats:italic>p</jats:italic> = 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/m<jats:sup>2</jats:sup>) 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.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>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.</jats:p></jats:sec>