Real-world analysis of apalutamide-associated skin adverse events in Japanese patients with advanced prostate cancer: a multi-institutional study in the Chu-shikoku Japan Urological Consortium

Background: Apalutamide-associated skin adverse events are more common in the Japanese than in the global population. However, limited clinical data have hampered further understanding. This real-world study investigated the clinical characteristics of skin adverse events in patients with advanced prostate cancer. Methods: We retrospectively reviewed 119 patient records from 16 institutions in Japan. Skin adverse events were graded according to the Common Terminology Criteria for Adverse Events (v5.0). The incidence and characteristics of skin adverse events (along with the clinical risk factors for their incidence, worsening, and recurrence) were evaluated. Results: Fifty-five patients (46.2%) experienced skin adverse events. The median times to the incidence and remission of skin adverse events were 62 and 30 days, respectively. Grade 3 skin adverse events were observed in 15 patients (12.6%). The median time from the first incidence to apalutamide interruption was significantly longer in patients with progression to grade 3 skin adverse events than in those without such a progression (8 vs. 0 days, p = 0.005). Skin adverse events were observed in 45.2% of patients who resumed apalutamide treatment (median treatment interruption time: 31.5 days). Sixteen patients (13.4%) permanently discontinued apalutamide due to skin adverse events. No significant clinical risk factors for the incidence, worsening and recurrence of apalutamide-associated skin adverse events were observed. Conclusions: Nearly half of the Japanese patients in this study experienced skin adverse events following apalutamide administration. The time to apalutamide discontinuation after the incidence of skin adverse events was positively correlated with the worsening of these events.