Bristol Myers Squibb disclosed a previously not-reported fatal event in its Breakfree-2 Phase 1 CAR T trial (zola-cel, zolacabtagene autoleucel) in progressive and highly active relapsing multiple sclerosis. The company said the participant died from septic pneumonia after late-onset motor symptoms that did not resolve with intermittent corticosteroids and IV immunoglobulin. BMS emphasized that it cannot yet determine whether the CAR T therapy caused the death and noted that CAR T expansion was consistent with other trial observations. The update follows earlier study halts tied to multiple patient deaths in a competitor’s trial. The disclosure matters for developers operating in the increasingly competitive MS CAR T space because it adds new post-infusion risk context and reinforces the central role of adverse-event root-cause analysis in next trial design and monitoring protocols.