Kyverna Therapeutics, Inc. (KYTX), a late-stage clinical biopharmaceutical company, announced positive primary analysis results from its registrational Phase 2 trial, KYSA-8, of miv-cel or KYV-101 in stiff person syndrome or SPS.
Following the news, KYTX is surging 35.94% at $13.20 in the overnight market.
Miv-cel (mivocabtagene autoleucel or KYV-101) is the firm's lead investigational CD19 CAR T-cell product candidate for the treatment of stiff person syndrome, myasthenia gravis, and lupus nephritis, as well as multiple sclerosis and systemic sclerosis. Trial Details
KYSA-8 is a single-arm, Phase 2 registrational trial evaluating Miv-cel in patients with SPS. The data cut-off for the primary analysis was November 26, 2025, with a median follow-up of 6.5 months after miv-cel infusion.
Patients received lymphodepletion with low-dose cyclophosphamide and Fludarabine followed by a single infusion of miv-cel at a target dose of 1×108 CAR T cells.
The primary endpoints are the change from baseline in the Timed 25-Foot Walk (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.
Key Findings
The trial met its primary endpoint, demonstrating a statistically significant improvement in the T25FW at week 16, with a median improvement of 46% from baseline.
Also, 81% of patients achieved clinically meaningful improvement of 20% or more from baseline, with nearly 1/3 of all patients walking at the speed of healthy adults by Week 16.
Of the 12 patients requiring a walking aid at baseline, 67% no longer needed walking assistance at week 16, reflecting meaningful functional independence.
The trial met all secondary endpoints, with significant mean improvements in mRS, HAI, DSI, and HSS of -0.8, -1.6, -1.5, and -3.2 points, respectively.
According to the firm, Miv-cel demonstrated a well-tolerated safety profile consistent with its potential for outpatient administration.
And for Grade 3/4 neutropenia observed in four patients, the firm said it is a known AE associated with lymphodepletion and CAR T-cell therapy and was manageable.
Also, the firm said serious treatment-related AEs occurred in three patients, all of which resolved fully without lasting effects.
The data will be presented in a late-breaking oral presentation at the American Academy of Neurology (AAN) Annual Meeting in Chicago.
KYTX has traded between $1.92 and $13.67 over the last year. The stock closed Tuesday's trade at $9.71, down 13.69%.
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