Apalutamide is an antiandrogen used to treat prostate cancer. Although it sometimes induces mild cutaneous adverse events and occasionally severe ones, clinical differences between severe and mild cases remain unclear. To assess the risks in patients experiencing apalutamide-related cutaneous adverse events (ARCAEs), we aimed to characterize severe and mild ARCAEs in terms of onset time and lymphocyte transformation test (LTT) for apalutamide. We reviewed 41 ARCAE cases: 24 from our institute and 17 from the literature, comprising (i) eight severe cases including six with toxic epidermal necrolysis, one with acute generalized exanthematous pustulosis, and one with drug reaction with eosinophilia and systemic symptoms, and (ii) 33 mild cases. Patients with evere cases developed ARCAEs significantly earlier than patients with mild cases (5.2 vs 9.6 weeks). No severe cases appeared ≥8 weeks after initiation of apalutamide. LTTs showed positive results in two of seven mild cases (28.6%) and four of four severe cases (100.0%). In conclusion, we found that severe ARCAEs are characterized by earlier onset and LTT positivity. Dermatologists and urologists should pay special attention to patients who develop ARCAEs <8 weeks after initiating apalutamide and/or show positive LTT results.
Keywords: apalutamide; drug eruption; lymphocyte transformation test; prostate cancer; toxic epidermal necrolysis.
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