Nivolumab-Induced Isolated Neutropenia.

Immune checkpoint inhibitors (ICIs) have been discovered to be associated with autoimmune toxicities that may present as dermatologic, gastrointestinal, hepatic, pulmonary, endocrine, and rarely hematologic reactions. Recent studies have also discovered hematological adverse effects as a result of ICI use of which isolated neutropenia is the gravest and the rarest manifestation. Asymptomatic neutropenia cannot be ignored, and close monitoring is, at least, warranted. Severe neutropenia with neutropenic fever needs hospital admission and prompt treatment to avoid further morbidity and/or mortality. In this report, we present a rare case of Grade 4 neutropenia resulting from nivolumab, anti-PD-1 antibody, in a patient diagnosed with invasive bladder cancer. The patient was successfully treated with steroids and supportive measures.