CAR T-Cell Trial Pause Signals New Manufacturing Risk Review

On August 24, 2026, Novartis paused 8 clinical trials of an experimental chimeric antigen receptor (CAR) T-cell therapy after 3 patients died from a severe immune reaction.¹ The therapy, known as rap-cel, was being studied as a treatment for a range of autoimmune and neurological conditions, including lupus, rheumatoid arthritis, vasculitis, multiple sclerosis, and myasthenia gravis.

The suspension took effect after Novartis learned of 3 cases of a life-threatening immune reaction in which the body's own defenses attack its organs.¹ The company said this type of reaction is a known and potentially fatal risk associated with CAR T-cell therapy generally, not one unique to this program. Two ongoing trials of the same therapy in patients with lymphoma and leukemia were not affected by the halt, underscoring that the safety concern has so far been observed specifically in the autoimmune and neurological patient population rather than in oncology settings.

What Is Driving the Safety Concerns?

CAR T-cell therapy involves extracting a patient's own immune cells, engineering them to recognize and destroy specific target cells, and reinfusing them back into the body.¹ The approach has produced meaningful results in blood cancers over the past decade, and developers have increasingly explored extending it to autoimmune and neurological disease, where dysfunctional immune cells are thought to drive disease progression. That expansion into new therapeutic areas is precisely what makes this safety signal significant: the risk-benefit calculus for a cancer patient with few remaining options differs substantially from that of a patient managing a chronic autoimmune condition through other, established therapies.

Novartis said it is conducting a comprehensive review of the deaths in coordination with independent safety boards, with the stated goals of understanding what happened and identifying ways to detect dangerous side effects earlier in treatment.¹ The company also said it is sharing information with health authorities and continuing to monitor patients who have already received the therapy.

What Does One of the Paused Trials Actually Involve?

Among the affected studies is a phase 2, open-label trial evaluating rapcabtagene autoleucel in adults with active, refractory systemic lupus erythematosus or active, refractory lupus nephritis.² The design called for a single infusion of the therapy following a lymphodepletion regimen intended to prepare the immune system ahead of treatment. Eligibility required confirmed systemic lupus erythematosus diagnosis, elevated disease activity scores, and an inadequate response to at least 2 prior therapies, while participants with significant organ dysfunction, certain infections, or recent thromboembolic events are excluded. Efficacy was being assessed against composite measures such as complete renal response and sustained disease remission at 24 and 52 weeks, alongside secondary measures covering corticosteroid use, fatigue, and flare frequency through 76 weeks. The trial's single-arm, unblinded structure reflects the early-phase nature of testing a novel modality in a population that has typically been treated with established immunosuppressive regimens rather than cell therapy.

Is This an Isolated Case or a Broader Signal?

The pause is not confined to a single company or program.¹ Bristol Myers Squibb (BMS) separately confirmed it has voluntarily paused studies of a competing CAR T-cell treatment while it reviews the safety data. BMS said the pause followed reports of temporary, reversible inflammation in patients, and that the therapy's overall safety profile otherwise remains consistent with other CAR T-cell treatments on the market.

Two companies pausing related programs within the same window suggests regulators, investigators, and manufacturers alike will be watching this immune-related toxicity closely as a class effect rather than a single-product issue.¹

This episode is a reminder that adapting an established modality for a new indication carries its own distinct risk profile, one that cannot simply be extrapolated from prior oncology experience.¹ It also has direct implications for clinical trial design, patient monitoring protocols, and manufacturing quality controls for cell therapies more broadly, particularly as more companies pursue CAR T-cell approaches outside of cancer. How regulators and sponsors respond, in terms of revised monitoring requirements, updated risk mitigation strategies, or changes to trial eligibility criteria, could shape the pace at which cell therapy platforms are permitted to expand into chronic disease treatment going forward.

References

1. Martinez X. Novartis pauses autoimmune cell therapy studies after deaths. Wall Street Journal. Updated September 1, 2026. https://www.wsj.com/health/pharma/novartis-pauses-autoimmune-cell-therapy-studies-after-deaths-62113d35
2. Novartis Pharmaceuticals. A study of rapcabtagene autoleucel in active, refractory systemic lupus erythematosus (SLE) or lupus nephritis (LN) patients (AUTOGRAPH-SLE/LN). ClinicalTrials.gov identifier: NCT06581198. June 3, 2026. https://clinicaltrials.gov/study/NCT06581198