Hair Repigmentation With Anti–PD-1 and Anti–PD-L1 Immunotherapy: A Novel Hypothesis

To the Editor The article by Rivera et al¹ is the first report of a previously undescribed side effect of checkpoint inhibitors: hair repigmentation (HR). In this significant case series of 14 patients, all patients received an anti–programmed cell death 1 (PD-1) and anti–programmed cell death 1 ligand 1 (PD-L1) antibody for the treatment of a lung cancer.