If given the green light by the FDA, a CAR T cell therapy from Kyverna Therapeutics would be the first approved treatment for stiff person syndrome. Scientists are now testing CAR T cell therapy in nearly a dozen autoimmune diseases linked to harmful B cells, including lupus, rheumatoid arthritis and a connective-tissue disease known as systemic sclerosis. Kyverna, the California-based company behind the SPS trial, is also running trials for neurological autoimmune conditions including generalized myasthenia gravis and progressive multiple sclerosis, or MS. CAR T cell therapies are transformative, Konig says. “They’re going to change the field — but there are risks.” · Another risk is that the once-vanquished disease will return. Doctors don’t know all the genetic and environmental conditions that trigger autoimmune disease. In 2017, the FDA approved the first CAR T cell therapies for two blood cancers, acute lymphoblastic leukemia and large B cell lymphoma. Soon after, scientists saw the first tantalizing hints that it might work for autoimmune diseases, too. In some cases, cancer patients with autoimmune disorders reported improvements in both conditions after treatment. At 40, Lynn Montgomery-Haga was diagnosed with stiff person syndrome, a rare autoimmune disease that can cause severe muscle spasms and rigidity. In 2024, she received an experimental CAR T cell therapy for her condition — then her mobility began to come back.Animations by Eric Pio; Edited by Damien S.

Kyverna Therapeutics' miv-cel demonstrated improved mobility and a favorable safety profile in patients with stiff person syndrome over one year. The company is preparing to file for priority review with the FDA this year, enhancing its prospects in the CAR T therapy space.

The FDA grants Orphan Drug Designation to therapies intended to address rare diseases or conditions affecting fewer than 200,000 people in the United States at the time of designation. Under the FDA's Orphan Drug Act, orphan drug status provides incentives, including tax credits, grants, and waiver of certain administrative fees for clinical trials, and seven years of market exclusivity following drug approval... QIVIGY is not approved for the treatment of Stiff Person Syndrome; the safety and effectiveness of QIVIGY for this use have not been established. ... Kedrion Biopharma collects and fractionates blood plasma to produce and distribute plasma‑derived therapies for rare, ultra‑rare, and debilitating conditions, including coagulation and neurological disorders, immunodeficiencies, and Rh sensitization. "Orphan Drug Designation is an important regulatory and clinical milestone as we explore the potential of QIVIGY to address the critical unmet need for people living with Stiff Person Syndrome," said Nisha Jain, M.D., Vice President, Global Clinical Development and Strategy at Kedrion Biopharma. "This designation underscores Kedrion's scientific commitment to advancing plasma-derived therapies for rare and ultra-rare disorders, both through targeted drug development and by expanding the therapeutic reach of established therapies for underserved patient communities." Scott Newsome, Professor of Neurology and Director of the Johns Hopkins Stiff Person Syndrome Center of Excellence, John Hopkins University School of Medicine, Baltimore MD. "Evaluating QIVIGY in structured clinical trials provides an opportunity to assess whether targeted intravenous immunoglobulin therapy can modify disease progression and meaningfully improve functional outcomes." The continued development of QIVIGY for SPS reflects Kedrion's broader commitment to addressing unmet needs across rare and ultra-rare disease communities and exploring new ways its therapies may support patients with limited treatment options.

A recent study investigates exteroceptive reflexes in patients with stiff person syndrome compared to other neurological conditions and healthy controls. This research may provide insights into the underlying mechanisms of reflex responses in rare neurological disorders.

Kyverna Therapeutics presents promising Phase 1 data for Miv-cel in Stiff Person Syndrome, showing 66.6% ACR70 response at Week 36 without high-grade CRS or ICANS. This data supports Miv-cel's potential to transform treatment for autoimmune diseases.