When Jan Janisch-Hanzlik enrolled in a clinical trial for her multiple sclerosis at age 49, she was already losing her independence. Frequent falls. A looming wheelchair. Medication that wasn’t working. She rang the clinic every other month until they were ready for her.
When she finally received the treatment, she spent the following week being monitored for potentially dangerous inflammation.
A few months later, she realised she’d stopped needing her glasses for double vision. Then she forgot to bring her cane to the supermarket. She didn’t need it.
The treatment she received wasn’t a new MS drug. It was CAR T cell therapy — a technology originally developed to fight cancer — and it may be on the verge of transforming how medicine treats an entirely different category of disease.
The Therapy That Rewires the Immune System
CAR T cell therapy works by extracting a patient’s own T cells, genetically reprogramming them to target and destroy a specific type of cell, and reinfusing them into the body. In cancer, it was designed to hunt malignant cells. First approved by the FDA for an aggressive form of leukemia in 2017, it has since produced long-term remissions in patients who had run out of other options.
The leap to autoimmune disease follows a compelling logic. Many conditions — lupus, multiple sclerosis, Graves’ disease, vasculitis, and dozens of others — are driven by B cells that have turned rogue, producing antibodies against the body’s own tissues instead of against real threats. CAR T is already extraordinarily effective at wiping out B cells in blood cancers. If it could do the same for misbehaving B cells in autoimmunity, it might not just suppress the disease — it could reset the immune system to the state it was in before the illness took hold.
The first autoimmune CAR T trial, in a lupus patient in Germany, reported positive results in 2021. Since then, hundreds of clinical trials have launched across conditions that have long been poorly served by existing treatments. Early results, while preliminary, have been striking in several cases. A trial for stiff person syndrome — a rare and debilitating autoimmune neurological condition with no approved treatment — tested a single dose of CAR T in 26 patients, most of whom struggled to walk normally and many of whom relied on mobility aids. Within months, most were walking faster, and eight had abandoned their walkers and canes entirely. Four to twelve months on, all 26 had come off every other immunotherapy they had been taking.
The Risks Are Real
Reprogramming the immune system comes with consequences. When CAR T cells attack their targets, they trigger inflammation that can cause high fevers, dangerous drops in blood pressure, and in serious cases, neurological symptoms. In the early days of cancer CAR T, these reactions were sometimes life-threatening. Physicians now have a decade of experience managing them, and the side effects are generally considered reversible.
More concerning for autoimmune patients — who typically don’t face the same life-or-death urgency as advanced cancer patients — are the long-term unknowns. CAR T treatment for cancer has been linked to a range of lasting issues, and in rare cases, the engineered cells themselves have turned malignant, causing new T cell-based cancers. The FDA has endorsed CAR T’s potential in autoimmunity while simultaneously warning of unpredictable long-term toxicity. Balancing that risk against the burden of an autoimmune disease — which varies enormously in severity from person to person — remains one of the field’s central unsolved questions.
Patients are also left temporarily vulnerable to infection while their B cell population recovers, sometimes for up to a year. Preventive antibiotics, antivirals, and vaccines help manage this, and research suggests that immune memory from prior vaccinations may survive the treatment in many cases.
The Cost Problem
Even setting aside safety concerns, CAR T’s current price tag is a formidable obstacle. Including hospital stays, cell engineering, and associated costs, treatment runs to hundreds of thousands of dollars per patient — placing it well beyond routine clinical use.
Two approaches are gaining momentum as potential solutions. The first is engineering CAR T cells to work within the body, skipping the expensive laboratory step of growing and modifying cells externally. The second — and more advanced — is an off-the-shelf approach using donor cells rather than the patient’s own, potentially allowing a single donor’s blood to produce CAR T cells for over a thousand patients at dramatically lower cost. Overcoming the immune mismatch between donor and recipient requires additional genetic modifications, but several research groups are already well advanced in this direction.
A next-generation version using mRNA rather than permanent DNA instructions is also being tested — the engineered cells attack B cells only as long as the mRNA persists, then lose their targeting ability. This approach eliminates the cancer risk associated with long-lived genetically modified cells, and early trials have shown two-thirds of patients improving with no serious long-term side effects.
Still Early Days
Jan Janisch-Hanzlik, who received an off-the-shelf version of the therapy, is doing better than she has in years. She took a trip to the Grand Canyon. She’s spending more time with her grandchildren — the very people whose potential future with MS helped convince her to take the risk in the first place.
She still has symptoms. She still asks her doctors whether she’s going to improve, plateau, or relapse. And she still gets the same answer: nobody knows yet. She was the first.
That uncertainty is the honest shape of where this field stands. The early results are remarkable enough to have drawn intense interest from both researchers and patients. The risks, costs, and long-term unknowns are real enough to demand caution. What seems increasingly clear is that CAR T cell therapy, built originally to fight cancer, may be far more than a cancer treatment, and that the immune system’s potential to reset itself, given the right instructions, is only beginning to be understood.