Apalutamide-Induced Drug Reaction With Eosinophilia and Systemic Symptoms (DRESS) Syndrome in a Patient With Metastatic Prostate Cancer: A Case Report

Metastatic prostate cancer is a leading cause of cancer-related morbidity and mortality.Androgen deprivation therapy (ADT) remains the foundation of systemic treatment, with novel androgen receptor inhibitors such as apalutamide increasingly used in patients with metastatic hormone-sensitive prostate cancer (mHSPC).Apalutamide is generally well tolerated.Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome is not recognized as an established side effect of apalutamide.We report the case of a man in his seventies who was initiated on apalutamide for mHSPC.Ten days after initiation, he developed a widespread maculopapular rash accompanied by biochemical abnormalities.Clinical assessment suggested a diagnosis of DRESS syndrome, most consistent with the criteria of Bocquet et al.The patient was managed with immediate discontinuation of apalutamide and initiation of high-dose systemic corticosteroids.He improved clinically and biochemically and subsequently transitioned to enzalutamide.This case highlights the importance of recognizing rare but potentially life-threatening adverse reactions associated with apalutamide.