Novartis has temporarily halted eight clinical trials of an experimental cell therapy for autoimmune and neurological diseases following three serious immune reactions, and Bristol Myers Squibb has paused enrollment in a parallel program. The setback lands on one of the most closely watched ideas in medicine: the attempt to use cancer cell therapy to reset a misfiring immune system.
Novartis confirmed the halt covering rapcabtagene autoleucel, an autologous CD19-directed CAR T therapy known as rap-cel or YTB323. The company said the pause would allow a fuller review of evolving clinical and safety data across the program after three serious cases of immune effector cell-associated hemophagocytic syndrome, or IEC-HS.
Novartis separately told the Wall Street Journal that three patients died, and described the fatal immune response as a known risk of CAR T therapies. The relationship between the three IEC-HS events described to Fierce Biotech and the three deaths reported to the Journal has not been spelled out publicly, and the timing of the deaths has not been disclosed.
The Trials and Patients Affected
Novartis confirmed the paused studies include Phase 2 trials in systemic lupus erythematosus and lupus nephritis, systemic sclerosis, ANCA-associated vasculitis, and idiopathic inflammatory myopathies. Also paused are Phase 1/2 studies in rheumatoid arthritis and Sjogren's disease, generalized myasthenia gravis, relapsing multiple sclerosis, and non-active progressive multiple sclerosis.
The company said patients already treated in these trials will continue to be monitored under protocol and that patient safety remains its highest priority.
Novartis said its oncology program for the same therapy is not affected by the halt. That program is in Phase 1/2 testing in chronic lymphocytic leukemia and small lymphocytic lymphoma, diffuse large B-cell lymphoma, adult acute lymphoblastic leukemia and high-risk large B-cell lymphoma.
Bristol Myers Squibb paused enrollment in autoimmune trials of zolacabtagene autoleucel, or zola-cel, its own CD19-directed CAR T candidate. A company spokesperson told BioPharma Dive the pause was voluntary and taken out of an abundance of caution to review clinical data across the program, and that the company aims to resume enrollment as quickly as possible. The company said it detected transient and reversible inflammatory events during routine safety surveillance and that the drug's safety profile remains consistent with the known profile of CAR T therapies. Results published in February had already detailed one IEC-HS case in a Phase 1 study of zola-cel.
The Reaction Behind the Halt
Immune effector cell-associated hemophagocytic syndrome is a severe inflammatory complication of cell therapy in which immune activation escalates and the body's own immune cells begin consuming blood cells. It can cause fever, low blood counts, liver injury and organ failure, and it can be fatal.
The condition is recognized in oncology CAR T practice and is not new. What makes its appearance here consequential is the population. Cancer patients receiving CAR T typically have exhausted other options and face a life-threatening malignancy, which shifts how much risk is acceptable. Many patients enrolling in autoimmune trials have serious and disabling disease but are not facing imminent death from it.
That difference is the heart of the risk-benefit question now under review. It is a question about acceptable trade-offs in a specific population, not a verdict on whether the science works.
A Possible Common Thread Analysts Have Flagged
Both paused programs share a technical feature. Novartis manufactures rap-cel on its T-Charge platform and Bristol Myers Squibb builds zola-cel on its NEXT T platform. Both are rapid manufacturing approaches that shorten the time cells spend growing outside the body.
The stated advantage is fresher, less exhausted cells that expand more vigorously once infused. Analysts at William Blair suggested that rapid manufacturing could be driving increased cell expansion and the reported toxicities.
That remains a hypothesis, not a finding. Neither company has attributed the events to manufacturing, and no regulator has issued a determination. It is worth watching because it would help explain why two separate programs hit similar problems around the same time, and because it would carry different implications than a problem intrinsic to CD19-directed therapy in autoimmune disease generally.
Other CD19-directed candidates for autoimmune disease remain in development, including programs from Cabaletta Bio, Miltenyi Biomedicine and Fate Therapeutics. Those use different manufacturing approaches, and Fate's candidate is an off-the-shelf product rather than a patient-derived one. Whether any of them are affected is unknown.
Where This Leaves Patients and the Field
No approved treatment is involved. Every therapy in this story is investigational and available only through clinical trials, so nothing changes for people currently taking approved medications for lupus, multiple sclerosis, myasthenia gravis or any other condition named here. Nobody should stop or alter a prescribed treatment because of this news.
Patients enrolled in the paused studies should hear directly from their trial site. Anyone who has not and wants clarity can contact the site coordinator rather than waiting. Patients who were awaiting screening or infusion will likely see delays.
For families who had been researching CAR T trials as a possible option, the practical effect is that the autoimmune pathway narrows for now. That is a real loss for people with severe refractory disease, and it deserves to be named rather than smoothed over.
What happens next depends on the safety reviews. Novartis has not given a timeline for its review or said whether the trials will resume, be redesigned with modified dosing or screening, or be discontinued. Bristol Myers Squibb has not given a timeline either. Regulators including the FDA have not publicly commented.
Trial status changes are typically posted to the federal registry, and updates to the oncology study record and the autoimmune study listings are the most reliable public signal of what happens next. MedicalDaily will report the outcome of both reviews.
Key Questions Answered
What did Novartis pause? Eight clinical trials of rapcabtagene autoleucel, an experimental CD19-directed CAR T therapy, across autoimmune and neurological diseases including lupus, systemic sclerosis, vasculitis, myositis, rheumatoid arthritis, Sjogren's disease, myasthenia gravis and multiple sclerosis.
Why were the trials paused? Novartis cited three serious immune effector cell-associated hemophagocytic syndrome events. The company separately told the Wall Street Journal that three patients died from a severe immune response.
Is Bristol Myers Squibb involved? Yes. The company voluntarily paused enrollment in autoimmune trials of its own CD19-directed CAR T candidate, zola-cel, citing transient and reversible inflammatory events found during routine safety surveillance.
Does this affect any approved treatment? No. All therapies involved are investigational and available only in clinical trials. No one should change an approved medication because of this news.
What is IEC-HS? A severe inflammatory complication of cell therapy in which immune activation escalates and immune cells begin consuming blood cells, potentially causing organ failure. It is a recognized risk in cancer CAR T therapy.
Are cancer CAR T trials affected? Novartis said its oncology program for the same therapy is not affected by the halt.
What should enrolled patients do? Contact the trial site coordinator for direct guidance. Novartis said patients already treated will continue to be monitored under protocol.
