AINEWS
Bristol Myers Squibb has paused its own trials as investigators probe a rare inflammatory syndrome the cancer CAR T era never had to map in autoimmune patients.
An engineered immune-cell therapy, repurposed from blood cancer into chronic autoimmune disease, just hit its first field-wide safety test. Three participants in trials of Novartis's rapcabtagene autoleucel, known as rap-cel, have died from immune effector cell-associated hemophagocytic syndrome, a rare inflammatory reaction. Novartis has paused eight autoimmune studies of the drug, and within days Bristol Myers Squibb has followed, halting new enrollment in parts of its own parallel program and framing the action as out of an abundance of caution.
The pause, first reported by BioSpace and BioPharma Dive, is the first time the autoimmune CAR-T pipeline has stopped for a single named safety signal. Rap-cel is a CAR-T therapy, meaning doctors draw a patient's T cells, engineer them in a lab to recognize a marker called CD19 on the surface of rogue B cells, then reinfuse them. In blood cancers, the same class of drug has produced durable remissions and a Nobel Prize. Over the last three years, the same approach has been retooled for lupus, multiple sclerosis, rheumatoid arthritis, and myasthenia gravis, the kind of chronic conditions where a one-time treatment could theoretically replace a lifetime of immunosuppression. The eight paused Novartis studies are testing rap-cel in exactly that population.
The danger is not the cytokine release syndrome oncologists were trained to watch for. Cytokine release syndrome, or CRS, is the fever and blood-pressure crash that follows most CAR-T infusions and is now well managed with steroids and a blocker called tocilizumab. IEC-HS is something else. It is a runaway activation of the immune system's histiocytes and macrophages, the cleanup cells that mop up after infection. In severe cases the syndrome drives fevers, organ swelling, ferritin levels in the tens of thousands, and a clotting failure that can kill within days. Standard CRS protocols do not catch it.
That may be why it surfaced now. Cancer CAR-T patients have, by definition, just had chemotherapy that wiped out much of their immune system, and they enter treatment in closely monitored academic centers. Autoimmune patients arrive with full-strength, hyperactive immune systems, often on long-term steroids, and they are being dosed under protocols first written for lymphoma. Whether the difference in patients, the speed at which rap-cel is being manufactured for a chronic-disease market, or something about the drug's own construct is driving the deaths remains officially unknown. Industry analysts have flagged rapid manufacturing and patient characteristics as plausible factors, but Novartis has stressed that the cause is still under review by independent data committees, and the company has not released a mechanistic finding.
Bristol Myers Squibb's response suggests the field does not yet know which of those buckets to blame. The company has paused enrollment in some of its own autoimmune CAR-T studies of zolacabtagene autoleucel, or zola-cel, after observing transient, reversible inflammatory events, with no deaths reported in its paused trials. At least one IEC-HS case had been previously documented in a BMS program.
Screening, randomization, and new dosing in the affected studies are suspended. Patients who have already received rap-cel or zola-cel continue to be monitored under their existing protocols, and the cancer-indication studies of both drugs are unaffected. Novartis has said the safety review is comprehensive and will set the terms under which any of the eight studies restart.
The wider ripple is harder to see from outside the trials. Cabaletta Bio, Kyverna Therapeutics, Janssen, and a handful of academic centers are running their own CD19 CAR-T programs in autoimmune disease, and every one of them is now auditing its screening criteria, lymphodepletion regimens, and post-infusion monitoring for the IEC-HS pattern. Thousands of patients with lupus, multiple sclerosis, rheumatoid arthritis, and myasthenia gravis who had been watching these trials as a possible functional cure are now inside that reckoning, waiting on a question the field has only just learned to ask: how does a therapy designed to extinguish a rogue immune system behave when the immune system it meets is already on fire.