Bristol Myers Squibb reports fatal outcome in multiple sclerosis CAR-T trial

Key points

• BMS reported a patient death in a Phase 1 trial of zolacabtagene autoleucel for multiple sclerosis, attributed to septic pneumonia following immunosuppression.
• The patient experienced late-onset motor symptoms that did not resolve with corticosteroids or intravenous immunoglobulin, leading to the administration of high-dose cyclophosphamide.
• BMS stated that the patient had prior complications that made it difficult to determine the exact root cause of the fatal outcome.
• Adverse event data showed that 42.4% of patients experienced cytokine release syndrome, and one patient had a Grade 4 ICANS event that resolved within four days.
• Efficacy results from the Breakfree-2 study showed that six of seven evaluable patients with highly active relapsing MS met criteria for no evidence of disease activity at week 26.

Background

This development follows earlier safety concerns in the CAR-T sector, including fatalities reported by competitors like Novartis earlier in 2026. BMS has recently faced scrutiny regarding safety signals in other autoimmune trials, such as a lupus study, though the company claims that specific issue has been resolved. The company has also been navigating patent cliff pressures for its blockbuster drugs Eliquis and Opdivo, while simultaneously reporting successes in other CAR-T therapies for multiple myeloma.

How outlets are covering it

STAT reported that BMS cited prior complications as a factor that confounded the ability to determine the root cause of the death. Endpoints News highlighted that BMS also addressed a safety signal in a separate lupus trial, suggesting a broader pattern of safety scrutiny in the sector. Seeking Alpha provided detailed clinical data, noting that while the death was serious, the trial showed significant efficacy results for multiple sclerosis patients, with most meeting criteria for disease activity stability. The outlets generally agree on the facts of the death and the trial's efficacy data but differ in emphasis, with STAT focusing on the causal ambiguity and Endpoints on the broader safety context.

Why it matters

The death underscores the risks associated with using CAR-T therapy for autoimmune conditions, a field that has seen growing interest but also increasing safety concerns. It may influence regulatory scrutiny and investor confidence in BMS's pipeline, particularly as the company seeks to offset losses from expiring patents on its major drugs. The incident also highlights the complex balance between efficacy and safety in early-stage clinical trials for novel therapies.

What to watch

BMS will likely face increased scrutiny from regulators and investors regarding the safety profile of its CAR-T therapies for autoimmune diseases. The company may need to provide further clarification on the root cause of the death and the safety signals in other trials. Investors will watch for any impact on BMS's stock price and future trial approvals, particularly as the company navigates patent cliff pressures and seeks to expand its pipeline in neurology and oncology.