A treatment originally designed to fight cancer is showing extraordinary results in autoimmune disease. CAR T cell therapy—which reprograms a patient's own immune cells to attack cancer—is being tested on patients with multiple sclerosis, lupus, Graves' disease, and dozens of other autoimmune conditions. Early results are striking.

From Cancer to Autoimmunity

CAR T (Chimeric Antigen Receptor T-cell) therapy was FDA-approved in 2017 for leukemia and has delivered long-term remission for many cancer patients. The basic premise is elegant: extract a patient's T cells, engineer them with molecular instructions to recognize and kill cancer cells, then reinfuse them back.

B cells are the key. In cancer, faulty B cells multiply uncontrollably. In autoimmune disease, B cells attack the body's own tissues instead of invading pathogens. It didn't take long for researchers to realize: if CAR T can eliminate bad B cells in cancer, why not in autoimmunity?

A German team pioneered the approach with a lupus patient in 2021, reporting positive results in the New England Journal of Medicine. Since then, dozens of trials have launched.

The Results Are Dramatic

In one study of stiff person syndrome (a rare, poorly understood autoimmune condition with no FDA-approved treatment), 26 patients received a single CAR T infusion. Before treatment, many struggled with slow, mechanical gait—12 used walkers or canes. Within 16 weeks, most walked faster, and eight no longer needed assistive devices for short distances.

Most remarkably: by four to 12 months post-treatment, all 26 patients were off all other immunosuppressive medications.

One first patient, Jan Janisch-Hanzlik with multiple sclerosis, was afraid to carry her grandchildren due to frequent falls. She volunteered for an experimental trial at the University of Nebraska. Now, nearly a year after treatment, she rarely falls, her double vision has resolved, and she no longer needs her daily three-hour naps. She recently enjoyed a trip to the Grand Canyon.

The Risks Are Real

But resetting the immune system isn't simple. CAR T can trigger severe inflammation—high fevers, low blood pressure, confusion, even dangerous brain inflammation. Physicians now have a decade of experience managing these side effects, and they're usually reversible.

There's also temporary immunosuppression. Patients are vulnerable to infections for up to a year post-treatment. This is manageable with preventive medications, though it's a real concern.

More troubling: FDA officials warn of "unpredictable long-term toxicity." CAR T cancer treatment has been linked to Parkinson's disease and, in rare cases, secondary T-cell cancers. For life-threatening cancer, that trade-off might be acceptable. For autoimmunity—which ranges from mild to severe—it's a harder calculation.

Next-Generation Safety

Researchers are already developing safer versions. Cartesian Therapeutics is testing CAR T cells encoded with mRNA (like COVID vaccines) instead of permanent DNA. The T cells persist just long enough to eliminate B cells, then lose their targeting ability. No long-term cellular modifications means no cancer risk.

In a recent trial, 15 autoimmune patients received this approach; two-thirds improved, and none suffered serious long-term side effects.

The Price Problem

The other major challenge: cost. CAR T therapy runs hundreds of thousands of dollars. Researchers are exploring "off-the-shelf" approaches using donor cells instead of personalised engineering. One researcher estimates a single donor could provide CAR T cells for over 1,000 patients at significant savings.

The Verdict

Amanda Piquet, an autoimmune neurologist at the University of Colorado, calls CAR T "a game changer." It's not a cure-all—patients retain some residual symptoms and may need monitoring. But for autoimmune patients who haven't responded to conventional treatment, it offers something unprecedented: a chance to essentially reset their immune system.

The biggest question remains: how safe is it long-term? The first generation of cancer patients are only a few years out. Time will tell.

Source: Ars Technica - CAR T Cell Therapy for Autoimmune Disease