Immunotherapies such as CAR T-cell therapy
were originally developed mainly to fight cancer. But scientists are now
investigating whether these personalized treatments, made from a
patient's own immune cells, could also help treat or even potentially
cure autoimmune diseases.
Researchers at Charité -
Universitätsmedizin Berlin have now tested CAR T-cell therapy in six
people with particularly severe rheumatoid arthritis. The world's first
clinical trial of its kind, reported in Nature Medicine,
produced encouraging early results. Disease activity fell substantially
in every participant, and by the end of the observation period, three
patients no longer needed rheumatoid arthritis medication.
Why Rheumatoid Arthritis Can Be So Difficult To Treat
Rheumatoid arthritis is a chronic autoimmune disease in which the
immune system mistakenly attacks the joints. Repeated inflammation
causes swelling and can eventually damage the joints.
Existing medications are often effective at controlling inflammation,
but they generally do not cure the disease. As a result, many patients
need lifelong treatment with anti-inflammatory drugs and medications
that suppress the immune system, which can also cause side effects.
For some people, even newer therapies do not work well enough.
Doctors describe these cases as treatment-refractory rheumatoid
arthritis. Patients can continue to experience pain, limited mobility,
and major reductions in quality of life despite trying multiple
treatments.
"One reason could be disease-driving B cells - memory cells of the
adaptive immune system that may survive in the lymph nodes, bone marrow
or joint tissue after an infection, where they produce harmful
antibodies directed against the body's own tissues and repeatedly
reignite the inflammation," explains Prof. David Simon, who designed the
trial for this patient group together with Prof. Gerhard Krönke at
Charité's Department of Rheumatology and Clinical Immunology.
The researchers are testing whether CAR T cells can seek out these
disease-driving B cells even when they are buried deep within body
tissues. Their goal is to eliminate as much of the abnormal B-cell
memory as possible and effectively give the B-cell system a new start.
Using Cancer Immunotherapy To Reset the Immune System
CAR T cells were first developed as a cancer treatment, but their
potential uses are expanding. In cancer therapy, a patient's immune
cells are modified so they can recognize and destroy tumor cells. For
autoimmune diseases, scientists instead want to direct those engineered
cells toward immune cells that help sustain the disease.
"The identifying marker on many B
cells, both abnormal B cells in cancers of the blood or lymphatic system
and disease-driving B cells in rheumatoid arthritis, is the surface
molecule CD19. You could think of it as a kind of 'name tag'," explains
David Simon. "To enable CAR T cells to detect and eliminate the
disease-causing cells, we equip patients' own immune cells with a
receptor that acts like a search sensor for CD19."
To produce this form of CD19 CAR T-cell therapy, doctors first
collect T cells from the patient's blood. T cells are immune cells that
normally help recognize and destroy infected or abnormal cells.
Scientists then genetically modify those T cells in the laboratory.
The cells receive a chimeric, or artificial, antigen receptor known as a
CAR, which is designed to bind specifically to CD19.
Before receiving the modified cells, patients undergo a short course
of preparatory chemotherapy. This temporarily lowers the number of
certain immune cells, creating room for the CAR T cells to multiply and
function effectively.
The engineered cells are then returned to the patient in a single
infusion. Once inside the body, they search for cells carrying CD19 and
attack them. This temporarily removes all CD19-positive B cells,
including long-lived disease-driving cells in the joints that can
otherwise be difficult to reach. By clearing out those cells, the
treatment may allow the immune system to reset.
First Trial in Severe Rheumatoid Arthritis
For the first clinical trial evaluating both the safety and
effectiveness of CD19 CAR T-cell therapy in rheumatoid arthritis, the
Charité team initially enrolled six patients with especially severe
disease.
The group included three women and three men between the ages of 31
and 69. During the previous decade, they had received as many as eight
targeted or biologic therapies, but none had controlled their disease
adequately.
Researchers wanted to learn whether CAR T cells could reach the
disease-driving B cells inside the joints and whether the approach could
do so safely.
The first phase of the COMPARE trial produced results the team considers highly encouraging.
"Disease activity decreased
markedly in all six patients. During follow-up of up to one year, three
patients were in sustained remission without any medication for
rheumatoid arthritis," reports Gerhard Krönke, who leads the joint
Clinical Rheumatology research group at Charité and the German
Rheumatology Research Center (DRFZ), a Leibniz Institute. "This is
particularly remarkable given that none of the established treatments
had previously been able to relieve their symptoms adequately."
CAR T Cells Reached Hidden Disease Reservoirs
The treatment appeared to do more than temporarily reduce
inflammation in the joints. Researchers found that the modified immune
cells also reached and eliminated disease-promoting B cells in deeper
locations, including the bone marrow, lymph nodes, and joint tissue.
During regular follow-up visits over the following 12 months, levels
of the autoantibodies associated with rheumatoid arthritis dropped
sharply.
David Simon adds: "When the B-cell system later recovered,
predominantly naïve B cells that had not yet been shaped by the disease
returned. In contrast, the B cells directed against the body's own
tissues that had been present before treatment were no longer detectable
in almost all patients, an indication that the treatment may indeed be
able to reset the pathological immune memory."
Importantly, antibodies generated by earlier vaccinations, including
those against chickenpox and tetanus, could still be detected. That
suggests protective antibody memory was largely preserved even though
the therapy caused a profound temporary depletion of B cells.
Researchers still need to determine whether the therapy has any longer-term effects on the immune system.
Promising Results, but the Therapy Remains Experimental
The trial suggests that a single CAR T-cell treatment can, in some
patients, produce a sustained period without symptoms or rheumatoid
arthritis medication. This state of disease inactivity is known as
remission.
For carefully selected patients whose rheumatoid arthritis does not
respond adequately to available treatments, researchers hope it may
eventually be possible to directly reset pathological immune memory and
stop the ongoing inflammation rather than continuously suppressing it
with medication.
However, CAR T-cell therapy for autoimmune diseases, including
rheumatoid arthritis, is still experimental. Researchers do not yet have
long-term experience with the treatment.
Responses also differed among the
six participants. Some did not achieve a complete response, and one
patient's disease returned after an initial period of medication-free
remission.
So far, however, the researchers consider the safety findings encouraging.
"After the participants received the CD19 CAR T cells, we observed
only a temporary, mild-to-moderate cytokine release syndrome (CRS) in
all participants, which was readily manageable. There were no severe
neurological complications or other serious adverse events, and
infections were rare," explains Dr. Marie Luise Hütter-Krönke, Medical
Director of the Hematology Early Clinical Trial Unit at Charité's
Department of Hematology, Oncology and Cancer Immunology.
A Larger Comparison Is Next
The second phase of the trial will include ten additional patients.
Researchers plan to compare CAR T-cell therapy with an already approved
rheumatoid arthritis drug that also targets B cells.
The comparison should help determine whether CAR T cells produce
stronger or longer-lasting effects and whether they truly reset immune
memory.
If these results are confirmed in this phase and in future larger
studies, CAR T-cell therapy could eventually offer another option for
people with severe rheumatoid arthritis whose lives are significantly
affected by the disease and who currently have no adequate treatment.
About the Study
The first of the two phases of the COMPARE study was designed to
assess the safety and effectiveness of CD19 CAR T-cell therapy in
treatment-refractory rheumatoid arthritis.
Major contributors included researchers from Charité's Department of
Rheumatology and Clinical Immunology and the Department of Hematology,
Oncology and Cancer Immunology at Campus Benjamin Franklin, along with
scientists from the Cluster of Excellence ImmunoPreCept, the German
Rheumatology Research Center (DRFZ), a Leibniz Institute, and the
Fraunhofer Institute for Translational Medicine and Pharmacology ITMP.
The study was initiated and designed at Charité and also received
support from Kyverna Therapeutics. The immunotherapy company had no role
in designing the study, collecting or analyzing the data, or presenting
the results.
Journal Reference:
- Fredrik N. Albach, Marie C. Rehm, Marie Luise Hütter-Krönke, Thanh
Hang Le, Julia M. Giezen, Murat Torgutalp, Arne Sattler, Ioanna
Minopoulou, Robert Biesen, Edgar Wiebe, Vincent Casteleyn, Thorben
Witte, Christian Furth, Jan Zernicke, Melanie Nuesch Germano, Johan
Verhagen, Artur Wilhelm, Maria Dzamukova, Klaus Engel, Simon
Schallenberg, Aimo Kannt, Nicole Ziegler, Michaela Fehringer, Udo
Schneider, Nadine Unterwalder, Mark Beling, Alexander Pfeil, Elpida
Phithak, Martin Krusche, Olaf Penack, Tobias Alexander, Werner Stenzel,
Manfred Wuhrer, Kamran Movassaghi, Thomas Dörner, Eicke Latz, Thomas
Vogl, Antonia Busse, Georg Schett, Hans Ulrich Scherer, Rene E. M. Toes,
Arnd Kleyer, Ulrich Keller, Lars Bullinger, David Simon, Gerhard
Krönke. CD19 CAR T cell therapy for treatment-refractory seropositive rheumatoid arthritis: a phase 1 trial. Nature Medicine, 2026; DOI: 10.1038/s41591-026-04603-3
Courtesy:
Charité - Universitätsmedizin Berlin. "A cancer therapy put severe
rheumatoid arthritis into remission." ScienceDaily. ScienceDaily, 29
August 2026. <www.sciencedaily.com/releases/2026/08/260828082330.htm>.