A new class of cellular therapies called CAR T-cell treatments is delivering remission in patients with severe autoimmune diseases that have resisted conventional drugs, offering hope for people who have exhausted other options. Researchers presented breakthrough data at the European Alliance of Associations for Rheumatology (EULAR) 2026 Annual Meeting showing that these "living drugs" can achieve sustained remission without ongoing immunosuppressive therapy in lupus, rheumatoid arthritis, and inflammatory muscle diseases.

What Are CAR T-Cell Therapies and How Do They Work?

CAR T-cell therapies are engineered living cells derived from a patient's own immune system. Doctors extract T cells (a type of white blood cell), reprogram them in the laboratory to recognize and attack disease-causing B cells, and then infuse them back into the patient. Unlike traditional drugs that require ongoing doses, these cellular therapies can provide long-lasting effects because the engineered cells persist in the body and continue working.

The key difference from standard treatments lies in how deeply and durably they deplete B cells, which are central to autoimmune disease. One expert explained the distinction: "When we're using B-cell depletion, for example, with a monoclonal antibody like rituximab, patients relapse around 3 months. This is completely different. There is a qualitative difference in depleting with a lifelong drug that is able to deplete very profoundly in tissues," noted Maria Leandro, a rheumatologist at University College London (UCL) Hospitals and an honorary senior lecturer at UCL in London, England.

How Are These Therapies Performing in Lupus Patients?

In a phase 1 trial called CARLYSLE, researchers tested a CAR T-cell therapy called obecabtagene autoleucel (obe-cel) in patients with severe, treatment-resistant systemic lupus erythematosus (SLE). The study enrolled patients with active lupus who had already failed multiple previous treatments, including B-cell targeted agents. All participants had severe kidney involvement, with most showing active lupus nephritis at baseline.

The results were striking. Five of six adult patients (83.3%) in the lower-dose cohort reached remission at a median of 5.1 months. Three patients (50.0%) achieved complete kidney response within the first month. Laboratory markers improved significantly, with anti-double-stranded DNA antibodies decreasing and complement 3 levels rising in most patients. Kidney function stabilized or improved, with decreased protein in the urine and stable or increased glomerular filtration rates.

Safety was favorable, with no cases of serious toxicity. The therapy demonstrated robust CAR T-cell expansion and profound B-cell depletion in all patients. Notably, when B cells recovered approximately 6 months after treatment, more than 90% were characterized as transitional or naive cells, meaning they were newly formed and less likely to be autoreactive.

What Results Are Emerging in Rheumatoid Arthritis?

The COMPARE trial provided the first clinical data for a CAR T-cell therapy called mivocabtagene autoleucel (miv-cel) in patients with active, treatment-resistant rheumatoid arthritis (RA). Six patients with high baseline disease activity and extensive prior treatment exposure (median of 6.5 biologic drugs) received a single infusion after lymphodepletion.

Following treatment, disease activity decreased across all patients, with a median 41% reduction in disease activity scores from baseline. Half of the patients achieved full clinical remission. Joint swelling counts dropped impressively, and imaging showed reduced local inflammation. Most importantly, four of six patients achieved sustained seroconversion to normal values for anti-cyclic citrullinated peptide (ACPA) antibodies, and five of six achieved normal rheumatoid factor levels.

One patient experienced a moderate flare after steroid withdrawal, but all others remained completely off background immunosuppressive therapies during follow-up. When B cells repopulated, they were predominantly naive or transitional phenotypes, while autoreactive cells remained absent.

Steps to Understanding CAR T-Cell Therapy for Autoimmune Disease

• Patient Selection: These therapies are currently being tested in patients with severe, refractory autoimmune diseases who have failed multiple conventional treatments, not as first-line therapy for newly diagnosed patients.
• Treatment Process: The procedure involves extracting the patient's own T cells, engineering them in a laboratory to target disease-causing B cells, and reinfusing them after lymphodepletion chemotherapy.
• Monitoring for Relapse: Researchers are tracking how long remission lasts and identifying which patients are at higher risk for disease recurrence, with some patients showing B-cell recovery around 5 to 6 months post-treatment.
• Safety Considerations: Early trials show favorable safety profiles with manageable side effects, though long-term safety data continues to accumulate as more patients are treated.

What About Other Autoimmune Conditions?

Beyond lupus and rheumatoid arthritis, researchers are testing CAR T-cell therapy in idiopathic inflammatory myopathies through the RESET-Myositis trial. This ongoing study is enrolling patients with dermatomyositis, antisynthetase syndrome, immune-mediated necrotizing myopathy, and juvenile idiopathic inflammatory myopathy. These conditions represent another group of severe autoimmune diseases where treatment options are limited.

The expansion into multiple autoimmune conditions reflects growing confidence in the cellular therapy approach. However, experts emphasize that identifying specific tissue biomarkers and cellular phenotypes through patient biopsies remains a research priority to better predict which patients will respond and which may relapse.

What's Next for These Therapies?

Phase 2 trials are actively recruiting patients. The Lumina trial is enrolling people with severe, refractory SLE and active lupus nephritis using the lower dose of obe-cel. Phase 2 of the COMPARE trial is ongoing with a randomized design comparing CAR T-cell therapy to rituximab, with an integrated crossover option for rituximab nonresponders at 6 months.

Researchers are also exploring off-the-shelf allogeneic natural killer (NK) cell platforms as alternatives to autologous CAR T therapies, which could potentially simplify manufacturing and expand access. These advances represent a significant shift in how severe, treatment-resistant autoimmune diseases may be managed in the coming years, moving from lifelong drug dependence toward potential long-term remission with a single cellular intervention.