Kyverna Therapeutics Presents Full One-Year Registrational Data Set Demonstrating Sustained Clinical Benefit of Miv-cel in Stiff Person Syndrome at MS Toronto

Kyverna says the one-year durability results further strengthen the miv-cel application package for stiff person syndrome.

Rhea-AI Summary

Kyverna Therapeutics (Nasdaq: KYTX) announced full one-year results from its registrational Phase 2 KYSA-8 trial of miv-cel in stiff person syndrome. Among 26 patients, median improvement from baseline in timed 25-foot walking was 49% at one year, versus 46% at week 16. Clinically meaningful improvement occurred in 77% at one year, and 92% remained free of chronic immunotherapies for the disease.

All secondary endpoints continued to be met at one year, with improvements in disability, walking ability, stiffness and sensitivity. Median improvement in six-minute walking distance reached 119 meters, versus 89 meters at week 16. No high-grade cytokine release syndrome or associated neurotoxicity, and no immune effector cell-associated inflammatory syndrome, occurred. Grade 3/4 neutropenia occurred in five patients; serious treatment-related adverse events in three patients all resolved.

13 points · 1 major

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0 major · 2 points

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Positive

• Major pointTimed 25-foot walk median improvement was 49% at one year versus 46% at week 16; one-year p < 0.0001.
• Moderate point92% (24/26) remained free of chronic immunotherapies for stiff person syndrome at one year.
• Moderate pointModified Rankin Scale disability scores improved by a mean -1.0 from baseline at one year (p = .0003).
• Moderate pointHauser Ambulation Index walking-ability scores improved by a mean -1.7 from baseline at one year (p < .0001).
• Moderate pointDistribution-of-Stiffness scores improved by a mean -1.6 from baseline at one year (p < .0001).
• Moderate pointHeightened Sensitivity Scale scores improved by a mean -2.8 from baseline at one year (p < .0001).
• Moderate pointSix-minute walking distance median improvement increased from 89 meters at week 16 to 119 meters at one year.
• Moderate pointPhysical functioning and mental health benefits persisted at one year, comparable to healthy adults on the 36-item survey.

5 minor points

• Minor pointClinically meaningful walking improvement occurred in 77% (20/26) at one year versus 81% (21/26) at 16 weeks.
• Minor point67% (8/12) of patients previously requiring walking aids continued not to require assistance.
• Minor pointOver one-third completed the timed 25-foot walk in <5 seconds, comparable to typical healthy-adult times.
• Minor pointB-cell reconstitution, the return of these immune cells, occurred alongside sustained efficacy and antibody reduction.
• Minor pointNo high-grade cytokine release syndrome or associated neurotoxicity, and no immune effector cell-associated inflammatory syndrome, occurred.

Negative

• Minor pointGrade 3/4 neutropenia, a low count of infection-fighting white blood cells, occurred in five patients and was manageable.
• Minor pointSerious treatment-related adverse events occurred in three patients; all fully resolved.

Key Figures

Follow-up population: 26 patients T25FW median improvement: 49% T25FW median improvement: 46% +5 more

Follow-up population

26 patients

KYSA-8 one-year follow-up

T25FW median improvement

49%

From baseline at one year; p < 0.0001

T25FW median improvement

46%

From baseline at week 16

Clinically meaningful T25FW improvement

77% (20/26)

At one year; defined as at least a 20% reduction from baseline

Free of chronic SPS immunotherapies

92% (24/26)

At one year

Six-minute walk distance improvement

119 meters

Median improvement at one year, versus 89 meters at week 16

Grade 3/4 neutropenia

5 patients

Reported as expected with lymphodepletion and CAR T-cell therapies, and manageable

Serious treatment-related adverse events

3 patients

All reported events had fully resolved

Historical Context

1 past event · Latest: Sep 24

1 event

1. Sep 24

   Clinical data

   24h Move

   -1.1%

   Reported KYSA-8 one-year results, including 49% timed-walk improvement and 92% off chronic immunotherapies.

24h Move is the share-price change in the day after each event; other market factors may also have contributed.

Key Terms

stiff person syndrome, cytokine release syndrome, immune effector cell-associated neurotoxicity syndrome, immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome

4 terms

stiff person syndrome medical

"patients with stiff person syndrome (SPS)"

A rare neurological disorder in which muscles become abnormally stiff and prone to painful spasms, often triggered by movement, noise, or emotional stress; it is usually caused by an immune system problem that interferes with normal nerve signals to muscles. Investors care because the condition creates demand for specialized diagnostics, long-term therapies, and clinical research; progress or setbacks in treatments, approvals, or trial results can materially affect companies developing drugs, medical devices, or diagnostic tests, similar to how a breakthrough in a small but underserved market can change a company’s prospects.

cytokine release syndrome medical

"no high-grade cytokine release syndrome (CRS)"

An intense immune overreaction in which the body's defense system releases a large surge of signaling proteins, causing fever, low blood pressure, breathing trouble or organ stress; imagine the immune system's alarm going into overdrive and flooding the body with emergency responders. Investors care because this side effect can slow or block regulatory approval, increase clinical trial costs and liabilities, limit how widely a therapy can be used, and therefore affect a drug's market value and sales potential.

immune effector cell-associated neurotoxicity syndrome medical

"immune effector cell-associated neurotoxicity syndrome (ICANS)"

immune effector cell-associated neurotoxicity syndrome (ICANS) is a brain-related side effect that can occur after treatments that activate powerful immune cells, such as engineered cell therapies. It can cause confusion, speech problems, seizures or coma when the immune response unintentionally harms brain function; think of an overenthusiastic security system that starts damaging the house it’s protecting. Investors care because ICANS affects clinical trial results, regulatory approvals, product labeling, treatment adoption, monitoring costs and potential liability, all of which influence a therapy’s commercial value.

immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome medical

"immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS)"

A severe, rare inflammatory reaction that can occur after powerful immune-based cancer therapies, where immune cells become overactive and start damaging the body's own organs and blood cells. Think of the immune system as an engine that gets stuck revving, triggering high fevers, organ strain and abnormal blood counts; for investors it matters because this safety issue can slow development, change regulatory requirements, raise treatment costs and influence clinical success and market acceptance.

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Miv-cel reversed disability and achieved durable efficacy across all primary and secondary endpoints through one year, with nearly all patients remaining off chronic immunotherapies 

Deep B-cell depletion demonstrated with a single dose supports the potential for broad immune reset enabled by miv-cel's unique construct

Consistent, well-tolerated safety profile with no high-grade CRS or ICANS, and no cases of IEC-HS in one-year follow-up

Data further strengthens SPS BLA package and supports potential for miv-cel to be the first approved therapy in SPS and first approved CAR T-cell therapy for autoimmune diseases

EMERYVILLE, Calif., Oct. 21, 2026 (GLOBE NEWSWIRE) -- Kyverna Therapeutics, Inc. (Nasdaq: KYTX), a late-stage clinical immunology company pioneering transformative therapies for people with neurologic autoimmune diseases, today announced the full one-year data set from KYSA-8, its registrational trial of miv-cel (mivocabtagene autoleucel, KYV-101) in patients with stiff person syndrome (SPS). The data will be presented today at MS Toronto 2026, the joint ACTRIMS-ECTRIMS meeting.

“The totality of the one-year durability data from the KYSA-8 trial is very encouraging and suggests miv-cel has the potential to fundamentally change how we treat stiff person syndrome, a progressive, disabling disease with no approved therapies,” said Amanda Piquet, M.D., FAAN, Director of Autoimmune Neurology at the University of Colorado Anschutz School of Medicine, Céline Dion Foundation Endowed Chair, and lead investigator of the KYSA-8 trial. “The positive primary endpoint results, together with the secondary and exploratory endpoint data, highlight the full clinical benefit of miv-cel with a single dose. Through one year, patients experienced significant improvements across multiple measures of disease burden, including disability, mobility, stiffness, hypersensitivity, physical functioning and mental health, with a well-tolerated safety profile.”

Poster Presentation:
Title: 1-Year Analysis of KYSA-8: the Pivotal, Multicenter, Phase 2 Study of Miv-cel (Mivocabtagene Autoleucel; Formerly KYV-101) CD19 CAR T-Cell Therapy in Stiff Person Syndrome
Presenter: Amanda Piquet, M.D., FAAN, Director of Autoimmune Neurology at the University of Colorado Anschutz School of Medicine
Poster ID: P0364
Date & Time: Wed., October 21, 2026, 4:30 – 6:30 PM ET

As reported at AAN 2026, the primary endpoint and all key secondary endpoints were achieved with statistical significance in KYSA-8. The one-year durability data being presented today further strengthens these positive results.

Efficacy highlights from one-year follow-up data on 26 patients include:

• Significant improvement in the timed 25-Foot Walk (T25FW) sustained at one year (p < 0.0001): median improvement from baseline of 46% at week 16 (primary endpoint) and 49% at one year.
• At 16 weeks and one year after receiving miv-cel, 81% (21/26) and 77% (20/26) of patients achieved clinically meaningful improvement (≥20% reduction from baseline) in T25FW, respectively, demonstrating sustained benefit for the vast majority of patients.
• Over one-third of patients completed T25FW in <5 seconds, comparable to a typical time for healthy adults.
• Of the 12 patients requiring a walking aid prior to treatment, 67% (8/12) continue to not require assistance.
• 92% (24/26) of patients remained free of chronic immunotherapies for SPS.
• At one year, the trial continued to meet all secondary endpoints, with significant mean improvements from baseline in Modified Rankin Scale, Hauser Ambulation Index, Distribution-of-Stiffness and Heightened Sensitivity Scale, of -1.0 (p = .0003), -1.7 (1.38; p < .0001), -1.6 (1.75; p < .0001) and -2.8 (2.11; p < .0001), respectively.

Exploratory endpoints, including additional efficacy measures continue to support miv-cel’s differentiated clinical profile:

• In the 6-minute walk test, responses deepened over time, with the median improvement in walking distance increasing from 89 meters at the 16-week primary endpoint measurement to 119 meters at one year, a nearly 6-fold improvement over the clinical minimally important change of 20 meters.
• Sustained clinical benefit at one year in physical functioning and mental health, comparable to healthy adults, across the 36-item short form health survey.
• B-cell reconstitution was observed with sustained efficacy and antibody reduction.
  
  

Miv-cel continued to demonstrate a well-tolerated safety profile, supporting its potential for outpatient administration:

• No high-grade cytokine release syndrome (CRS) or immune effector cell-associated neurotoxicity syndrome (ICANS), and no cases of immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome (IEC-HS).
• Grade 3/4 neutropenia, an expected adverse event (AE) with lymphodepletion and CAR T-cell therapies, was observed in five patients and was manageable.
• Serious treatment-related AEs occurred in three patients, all of which have fully resolved.
  
  

“This is a remarkable data set, demonstrating consistent and durable clinical benefit across primary, secondary, and exploratory endpoints, with a well-tolerated safety profile,” said Warner Biddle, Chief Executive Officer of Kyverna Therapeutics. “These results reinforce miv-cel’s potential best-in-class clinical profile, which may meaningfully change the trajectory of stiff person syndrome with a single dose, while allowing patients to remain free of chronic immunosuppressive therapies. We look forward to bringing this transformative therapy to patients as quickly as possible.”

About KYSA-8 Registrational Clinical Trial
KYSA-8 is a single-arm registrational Phase 2 trial in which 26 adult patients with SPS, who had an inadequate response to at least one immunotherapy treatment, received a single dose of miv-cel. The primary endpoints are the change from baseline in the T25FW at 16 weeks and the incidence and severity of adverse events (AEs). Secondary endpoints measuring disability, stiffness, hypersensitivity, and mobility include the Modified Rankin Scale (mRS), Distribution-of-stiffness Index (DSI), Heightened Sensitivity Scale (HSS), and Hauser Ambulation Index (HAI), respectively.

About miv-cel (mivocabtagene autoleucel, KYV-101)
Miv-cel is a fully human, autologous, CD19-targeting CAR T-cell therapy with CD28 co-stimulation. It is uniquely designed for potency and tolerability with the potential to achieve deep B-cell depletion, reset the immune system, and deliver durable drug-free, disease-free remission in autoimmune diseases with a single dose. Miv-cel is under investigation for B-cell driven autoimmune diseases and is produced using a well-established, validated manufacturing process. To date, more than 100 patients have been treated with miv-cel across a range of autoimmune diseases, and the clinical data demonstrates a consistent and well-tolerated safety profile.

About Stiff Person Syndrome (SPS)
SPS is a rare, progressive neurologic autoimmune disease characterized by muscle stiffness and painful muscle spasms, impacting mobility and gait. Stiffness, rigidity, and spasms in the torso, arms, and legs lead to progressive disability causing up to 80% of patients to lose mobility, requiring walking aid assistance or wheelchair use^1-3. SPS has been shown to lead to permanent disability and increased risk of mortality³. Most patients with SPS have antibodies to glutamic acid decarboxylase 65 (GAD65) or the glycine receptor, which disrupt normal inhibitory neurotransmission, contributing to the hallmark symptoms of SPS. There are currently no FDA-approved treatments for SPS. Current treatment options include symptomatic treatments, off-label immunotherapies, such as intravenous immunoglobulin (IVIg), rituximab and plasmapheresis, as well as supportive care and physical, speech, occupational, and psychiatric therapy; however, the majority of patients have inadequate or no response to these treatment options. An estimated 6,000 patients are diagnosed with SPS in the United States^4-5.

About Kyverna Therapeutics
Kyverna Therapeutics, Inc. (Nasdaq: KYTX) is a late-stage clinical immunology company pioneering differentiated therapies with curative potential for neurologic autoimmune diseases. Kyverna’s lead autologous CD19-targeting CAR T-cell therapy candidate, miv-cel (mivocabtagene autoleucel, KYV-101), has demonstrated the potential to fundamentally change the treatment paradigm across multiple B-cell-driven autoimmune diseases. Kyverna is advancing its potentially first-in-class neuroimmunology franchise with its recently completed registrational trial in stiff person syndrome (SPS) and an ongoing registrational trial for generalized myasthenia gravis (gMG).

Miv-cel has received three FDA Regenerative Medicine Advanced Therapy (RMAT) designations, in SPS, gMG, and non-active secondary progressive multiple sclerosis (naSPMS) based on compelling clinical data and significant unmet need, further reinforcing the therapy's potential across neuroimmunology. Additionally, the Company continues to advance new innovations that broaden access and choice for patients, expanding its leadership position in the field. For more information, please visit https://kyvernatx.com.

Forward-Looking Statements
Statements in this press release about future expectations, plans and prospects, as well as any other statements regarding matters that are not historical facts, may constitute “forward-looking statements.” The words, without limitation, “anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,” “may,” “plan,” “potential,” “predict,” “project,” “should,” “target,” “will,” “would” and similar expressions are intended to identify forward-looking statements, although not all forward-looking statements contain these or similar identifying words. Forward-looking statements in this press release include, without limitation, those related to: the potential for a single dose of miv-cel to provide a broad immune reset; miv-cel’s potential to fundamentally change how stiff person syndrome is treated; miv-cel’s potential outpatient administration; miv-cel’s potential best-in-class clinical profile; miv-cel’s potential to meaningfully change the trajectory of stiff person syndrome with a single dose while allowing patients to remain free of chronic immunosuppressive therapies; the potential for miv-cel to achieve deep B-cell depletion, reset the immune system, and deliver durable drug-free, disease-free remission in autoimmune diseases with a single dose or to fundamentally change the treatment paradigm across multiple B-cell-driven autoimmune diseases; the possibility that miv-cel may be the first approved treatment for patients with SPS or the first approved CAR T-cell therapy for autoimmune diseases; Kyverna’s pipeline opportunities; and Kyverna’s potentially first-in-class neuroimmunology franchise. Actual results may differ materially from those indicated by such forward-looking statements as a result of various important factors, including: uncertainties related to market conditions; risks related to the timing and outcome of regulatory submissions and interactions with the FDA; the ability to enroll patients in clinical trials on anticipated timelines; the possibility that topline results may change following further analysis or differ from final results; the possibility that results from prior clinical trials, named-patient access activities and preclinical studies may not necessarily be predictive of future results; and other factors discussed in the “Risk Factors” section of Kyverna’s most recent Annual Report on Form 10-K and Quarterly Reports on Form 10-Q that Kyverna has filed or may subsequently file with the U.S. Securities and Exchange Commission. Any forward-looking statements contained in this press release are based on the current expectations of Kyverna’s management team and speak only as of the date hereof, and Kyverna specifically disclaims any obligation to update any forward-looking statement, whether as a result of new information, future events or otherwise.

Contact:
Investors: InvestorRelations@kyvernatx.com
Media: media@kyvernatx.com

¹ Rakocevic G, et al. BMC Neurol. 2019;19:1.
² Dalakas MC. Nat Rev Neurol. 2024;20(10):587-601.
³ Duddy ME, Baker MR. Front Neurol Neurosci. 2009;26:147-165.
⁴ Crane PD, et al. Neurology. 2024;103(12):e210078.
⁵ Analysis of 2024 Komodo U.S. Claims Data.

FAQ

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What did Kyverna's KYSA-8 trial show for miv-cel in stiff person syndrome at one year?

Among 26 patients, median improvement from baseline in the timed 25-foot walk was 49% at one year, versus 46% at week 16. Clinically meaningful improvement, defined as a ≥20% reduction from baseline in walking time, occurred in 77% (20/26) at one year. All secondary endpoints continued to be met.

What safety findings did Kyverna report for miv-cel at one year?

There were no high-grade cytokine release syndrome or associated neurotoxicity events, and no cases of immune effector cell-associated hemophagocytic lymphohistiocytosis-like syndrome, an inflammatory complication. Grade 3/4 neutropenia occurred in five patients and was manageable. Serious treatment-related adverse events occurred in three patients, all of which fully resolved.