A first clinical trial at Charité–Universitätsmedizin Berlin suggests that CD19 CAR T-cell therapy may reduce disease activity in people with severe rheumatoid arthritis that has not responded adequately to multiple treatments. All six participants improved, and three remained in remission without rheumatoid arthritis medication during follow-up of up to one year.
How the treatment works
CAR T cells are made from the patient’s own T cells. These cells are collected, genetically modified to recognize CD19, and then returned to the patient after preparatory chemotherapy.
CD19 is present on many B cells. In rheumatoid arthritis, some B cells may contribute to disease by producing autoantibodies and maintaining abnormal immune memory in tissues such as the joints, lymph nodes, and bone marrow. The treatment aims to eliminate these cells and allow a new, predominantly naïve B-cell population to develop.
What the study found
The six participants had severe, seropositive, treatment-refractory disease and had previously received up to eight targeted or biologic therapies. Disease activity fell in all patients, rheumatoid arthritis-associated autoantibodies declined, and three achieved sustained medication-free remission during the reported follow-up.
The researchers also reported that protective vaccine antibodies remained detectable despite extensive B-cell depletion. This suggests that some established immune memory may be preserved, although the long-term effects remain uncertain.
Safety findings were encouraging: all participants experienced only temporary mild-to-moderate cytokine release syndrome, and no severe neurological complications were reported. However, the study was too small to assess uncommon or delayed risks reliably.
Why caution is needed
This was a small, early-phase study involving only six highly selected patients and no reported randomized control group. One patient relapsed after an initial medication-free remission, and responses were not identical in every participant.
The findings therefore cannot be generalized to newly diagnosed rheumatoid arthritis, milder disease, or patients who respond to standard treatment. CAR T-cell therapy also requires complex manufacturing, chemotherapy, specialized monitoring, and long-term follow-up.
What comes next
A second phase of the COMPARE trial will evaluate additional patients and compare CAR T-cell therapy with an established B-cell-directed rheumatoid arthritis treatment. Larger and longer studies must determine whether the benefits are durable, whether joint damage is prevented, and which patients are most likely to benefit.
For now, CD19 CAR T-cell therapy should be regarded as experimental for rheumatoid arthritis. The Charité results provide an important proof of concept that targeted immune-cell therapy may produce drug-free remission in some treatment-refractory patients—but they do not yet establish CAR T cells as a cure or routine clinical treatment.
Source: Charite universitätsmedizin berlin; nature medicine
