The interleukin‐6 connection: Understanding cytomegalovirus reactivation following CAR ‐T‐cell therapy

Of 84 patients with acute lymphoblastic leukaemia, non-Hodgkin lymphoma or multiple myeloma, 22 developed cytomegalovirus (CMV) viraemia following chimeric antigen receptor modified T (CAR-T) cell therapy, resulting in a proportion of 26% and a median time to reactivation of 15.5 days. Sustained high level of interleukin-6 (IL-6) is a significant risk factor for CMV reactivation without significant interaction across subgroups of diagnosis and target. Other risk factors include ≥3 grade cytokine release syndrome (CRS), B-cell maturation antigen (BCMA)-directed CAR and high-dose corticosteroids. Excessive IL-6 during CRS play an important role in the frequent CMV reactivation following CAR-T-cell immunotherapy.