CAR T-cell therapy for autoimmune diseases hits a serious roadblock

Novartis paused eight clinical trials of its experimental CAR T-cell therapy, rapcabtagene autoleucel (rap-cel), on August 24 after three patients died from a severe, life-threatening immune reaction. The affected trials spanned a range of autoimmune and neurological conditions — including lupus, rheumatoid arthritis, vasculitis, multiple sclerosis, and myasthenia gravis. Two rap-cel trials in lymphoma and leukemia patients were not affected.

In response, Bristol Myers Squibb also voluntarily paused its own comparable CAR T program — zolacabtagene autoleucel (zola-cel) — as a precautionary measure. Experts believe both therapies' rapid manufacturing platforms may be producing T cells that expand too aggressively in patients, potentially triggering a dangerous inflammatory syndrome known as IEC-HS (immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome).

Key Takeaways:

• IEC-HS — a severe overactivation of the immune system — is a known but serious risk of CAR T therapy and is the suspected cause of the three deaths
• Autoimmune patients differ from oncology patients: they're often younger, not facing imminent death, and have other treatment options — raising the risk-benefit bar
• Experts say this is not the end of CAR T in autoimmunity, but a call to better predict and intercept dangerous side effects early

Why it matters: CAR T-cell therapy has shown remarkable, drug-free remissions in autoimmune patients who had exhausted other options. These deaths don't erase that promise, but they underscore the urgent need to refine patient selection, manufacturing processes, and safety monitoring before the field can move forward confidently.