MGFA Session 2026: Single CAR T-cell therapy dose eases gMG up to 1.5 years
Most participants' symptoms now have little to no impact on their daily lives
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- A single dose of mivocabtagene autoleucel CAR T-cell therapy led to reductions in symptom severity in generalized myasthenia gravis.
- Those reductions were sustained for up to 1.5 years, according to findings from the Phase 2 part of a clinical trial.
- Most participants reached a state where their gMG symptoms have little to no impact on their daily lives.
A single dose of Kyverna Therapeutics’ experimental CAR T-cell therapy mivocabtagene autoleucel (miv-cel) led to reductions in symptom severity among people with difficult-to-treat generalized myasthenia gravis (gMG) that have been sustained for up to 1.5 years.
Importantly, most participants reached a state where their gMG symptoms have little to no impact on their daily lives and remained free of the need for other immunosuppressive treatments after receiving miv-cel, also known as KYV-101.
These are the updated findings from the Phase 2 part of the Phase 2/3 KYSA-6 clinical trial (NCT06193889), which were recently reported by Kyverna in a press release and presented by trial investigator Srikanth Muppidi, MD, at the Myasthenia Gravis Foundation of America scientific session during the American Association of Neuromuscular & Electrodiagnostic Medicine annual meeting.
“Demonstrating that a single dose of miv-cel can deliver sustained, drug-free remission for up to a year and a half with a consistent safety profile is a remarkable outcome for patients living with generalized myasthenia gravis,” Muppidi, of Stanford Medicine, said in an emailed statement to Myasthenia Gravis News.
The trial’s Phase 3 portion, which is testing miv-cel against standard of care gMG treatments, is still recruiting participants, with enrollment expected to finish in 2027.
Miv-cel targets B-cells that produce damaging antibodies
gMG is caused by self-reactive antibodies that target proteins needed for nerve-muscle communication, leading to muscle weakness and fatigue. Miv-cel is a chimeric antigen receptor (CAR) T-cell therapy designed to ease gMG severity by eliminating B-cells, the immune cells responsible for producing these damaging antibodies.
It involves collecting a person’s own immune T-cells and engineering them to carry a special protein (CAR) that recognizes and binds to a specific protein at the surface of B-cells. When returned to the body, these T-cells are equipped to specifically seek out B-cells and promote their destruction.
Miv-cel is given as a single infusion into the bloodstream after a short course of chemotherapy, which helps clear out existing immune cells and make space for the engineered cells. The therapy is also designed in a way that may reduce the release of signaling molecules that can cause known immune-related side effects of CAR T-cell therapies.
Kyverna hopes that the one-time treatment may reduce the reliance on chronic immunosuppressive therapies for people with gMG, which can compromise the body’s ability to fight infections and cause other side effects.
The KYSA-6 trial is testing miv-cel in people with gMG whose symptoms were not adequately controlled with available therapies. All are positive for antibodies against the acetylcholine receptor or muscle-specific kinase proteins, the two most common types of disease-driving antibodies.
Most participants remained off immunosuppressants at last follow-up
In its Phase 2 part, seven participants received a single miv-cel infusion. Early data demonstrated that the treatment quickly led to clinically meaningful reductions in three disease severity measures: Myasthenia Gravis Activities of Daily Living (MG-ADL), Quantitative Myasthenia Gravis (QMG), and Myasthenia Gravis Composite Scores (MGC).
The new analysis covered data up to June 2026, at which point five participants had been followed for at least a year and up to 1.5 years. The other two participants have been followed for nine months and six months.
By six months, all seven patients had achieved substantial and clinically meaningful reductions in MG-ADL, QMG, and MGC scores. These improvements were maintained for a year or longer in all five people who reached that time point.
“The benefit is clearly persistent all the way up to [1.5 years],” Muppidi said in the presentation.
Moreover, four participants (57%) had maintained minimal symptom expression, reflecting little to no impact of the disease on daily activities, as of their last follow-up.
Achieving minimal symptom expression while freeing patients from lifelong immunosuppressants represents a significant clinical milestone and highlights the potential to meaningfully change the treatment paradigm.
All seven participants remained free of the need for other MG immunotherapies after six months, with six of them (85.7%) remaining off immunosuppressants at their last follow-up.
“Achieving minimal symptom expression while freeing patients from lifelong immunosuppressants represents a significant clinical milestone and highlights the potential to meaningfully change the treatment paradigm,” Muppidi said.
Miv-cel was generally well-tolerated and lowered levels of disease-causing antibodies without compromising the immune system’s ability to produce infection-fighting antibodies.
“These 1-year follow-up data in gMG show the transformative potential of resetting the immune system with a single dose of miv-cel,” Naji Gehchan, MD, Kyverna’s chief medical and development officer, said in an emailed statement. “With 100% of patients achieving clinically meaningful improvements and 86% remaining off chronic immunosuppressants, these results distinguish miv-cel from existing therapies and reinforce our goal of delivering true, long-term, drug-free, disease-free remission with a manageable safety profile for people living with gMG.”
Note: The Myasthenia Gravis News team is providing virtual coverage of the Myasthenia Gravis Foundation of America’s scientific session at the American Association of Neuromuscular & Electrodiagnostic Medicine Annual Meeting on Sept. 29. Go here to see the latest stories from the conference.
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