Varicella zoster virus reactivation reported with isatuximab use.

Isatuximab is a CD38-directed antibody indicated for the treatment of relapsed or refractory multiple myeloma. The Division of Pharmacovigilance at the U.S. Food and Drug Administration (FDA) reviewed case reports from postmarketing sources, including the FDA Adverse Event Reporting System (FAERS), PubMed, and Embase, to investigate a potential association between isatuximab and the risk of varicella zoster virus (VZV) reactivation. We identified 20 reports of which 15 met our case definition and causality criteria. All 15 patients (80% male, median age = 60 years) received isatuximab for a hematologic neoplasm; eight (53%) for previously untreated multiple myeloma. All cases described additional risk factors for VZV reactivation, including concomitant proteasome inhibitor and/or immunomodulatory drug (n = 10, 67%) use. Based on this postmarket analysis, the U.S. Prescribing Information for isatuximab was updated to include this new safety information, including recommendations for antiviral prophylaxis.