A promising CAR-T cell therapy has helped people with stiff person syndrome regain abilities that the progressive neurological disorder had taken from them. Early results include patients walking again, returning to work, and resuming daily activities without assistance.

Stiff person syndrome, also called Moersch-Woltman syndrome, affects the central nervous system and becomes worse over time. It can cause severe muscle stiffness in the torso, arms, and legs, sometimes beginning in one area before spreading through more of the body.

Sounds, touch, and emotional distress can trigger painful muscle spasms. Even an ordinary noise such as a car horn can cause discomfort, contribute to falls, and make leaving home a daunting experience.

As symptoms advance, patients can lose mobility and independence. Existing treatments largely seek to stop the condition from worsening, rather than restoring the level of function that a patient has already lost.

Stiff person syndrome is thought to be an autoimmune condition in which the immune system attacks the body. One form, known as paraneoplastic syndrome, occurs as part of the immune system’s response to a cancerous tumor.

In those cases, cancer fighting T cells can mistakenly attack healthy tissue and cause greater damage to the body than to the tumor. Slurred speech, memory loss, loss of muscle tone, and difficulty walking may appear before the cancer is discovered.

Researchers are now investigating whether immune cells can be reprogrammed to work in a patient’s favor. Chimeric antigen T cell therapy, known as CAR-T cell therapy, removes T cells, genetically engineers them, and returns millions of them to the body through an infusion targeting a specific problem.

For people with stiff person syndrome, the novel therapy was administered as a single treatment. It was designed to reset the immune system and reduce the severity of symptoms caused by the autoimmune condition.

The research remains in its early stages, but a new paper describes encouraging results. The approach builds on the use of CAR-T therapy in some cancers while exploring its potential against autoimmune neurological disease.

“CAR-T therapy has already transformed the treatment of some cancers, and we are now beginning to see its potential in autoimmune neurologic diseases,” said Dr Sean Pittock, chair of the Department of Neurology at Mayo Clinic in Rochester.

“The results in stiff person syndrome offer tremendous hope, not only for people living with this disease but potentially for patients with other immune-mediated neurologic conditions where effective treatment options remain limited.”

The study included the case of Shari St. Germain, who began experiencing symptoms in 2021. By 2024, standard treatments were no longer helping, and rigidity and falls triggered by loud sounds had left her struggling to walk or venture outside.

Following treatment, St. Germain reached the milestone of walking on a treadmill again. Her progress represented a return of function that existing approaches rarely deliver for patients with the condition.

Jonathan Walden had also reached a point where he could no longer walk or complete routine tasks without assistance. After receiving the therapy, he experienced a significant improvement in his quality of life and said he had not experienced another episode.

“I can go to work every single day. I can do everything I did before. I go hunting; I can go fishing,” Walden said. “I have not had one episode since receiving treatment.”

Pittock said important questions about the therapy remain, but the results open an exciting area of research for a disease whose progression had been considered irreversible. Researchers now need to determine whether the improvements continue over time.

“What was most striking was the degree of improvement we saw in some patients,” said Dr Anastasia Zekeridou, a neurologist and researcher at Mayo Clinic.

“With existing treatments, we may be able to improve symptoms, but we very rarely see patients return to their previous level of function. These early results are very encouraging, and the key question now is whether those improvements will be sustained over time.”

The findings were published in JAMA Neurology. While more must be learned, the early results offer hope that CAR-T cell therapy could restore meaningful function rather than merely slowing further decline.