KYTX Stock Reverses Gains After One-Year Cell Therapy Trial Data — But CEO Says Disease Burden Justifies A Premium Price

Chief executive Warner Biddle said the therapy’s durability “exceeded even our expectations.”

• Miv-cel is a one-dose treatment made from a patient’s own immune cells and designed to reset the attack on the nervous system.
• In the 26-patient stiff person syndrome study, walking speed improved by a median 49% at one year.
• Kyverna said it will fold the one-year stiff person syndrome results into a rolling application for U.S. approval, still slated to finish in the fourth quarter of 2026.

Shares of Kyverna Therapeutics (KYTX) fell on Thursday even after the company reported that a one-time cell therapy kept helping patients with stiff person syndrome (SPS) and generalized myasthenia gravis a full year later.

Investors had already priced in much of the good news after earlier trial readouts. Thursday’s update confirmed that benefits lasted, but did not deliver a surprise.

Kyverna opened near $7.80, up more than 10%, then reversed, trading as low as about $6.68, or 5.5% lower than Wednesday’s close.

What The Data Showed

Miv-cel is a one-dose treatment made from a patient’s own immune cells and designed to reset the attack on the nervous system. In the 26-patient stiff person syndrome study, walking speed improved by a median 49% at one year. Nearly all patients who had gained ground by week 16 still held that gain. Most no longer needed long-term immune-suppressing drugs, and two-thirds of those who once used a walking aid no longer needed one.

Safety stayed clean: No severe cytokine storms or the most serious treatment-related brain side effects. Five patients had expected low white-cell counts; all were manageable, and none had serious infections, the company said.

A smaller myasthenia gravis study of seven patients showed the same theme. All improved on standard symptom scores by six months, and those followed for a year or more kept the benefit. Most remained off chronic medicines.

What Executives Emphasized

Chief executive Warner Biddle said the durability “exceeded even our expectations.”

Biddle said SPS is expensive and devastating: treating one patient can cost $700,000 to more than $1.5 million over three years, and fewer than 1 in 5 patients are still working four years after diagnosis. That burden, he said, supports charging more than the $500,000 to $600,000 now paid for similar cancer cell therapies. About 6,000 people in the U.S. have been diagnosed. At launch, Kyverna plans to start with the 2,000 to 2,500 patients who are not getting enough help from current off-label drugs, many of them treated at about 10 major academic hospitals.

What Comes Next

Kyverna said it will fold the one-year stiff person syndrome results into a rolling application for U.S. approval, still slated to finish in the fourth quarter of 2026. Fuller data will be presented at medical meetings later this month and in October. A larger myasthenia gravis trial is expected to finish enrolling around mid-2027.

How Did KYTX Retail Traders React?

On Stocktwits, retail sentiment around KYTX stock jumped from ‘neutral’ to ‘extremely bullish’ over the past 24 hours, while message volume increased from ‘high’ to ‘extremely high’ levels.

A Stocktwits user said the stock is a “bargain” at current prices.

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“Very interesting platform is the durability holds up,” another said about the trial results.

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KYTX stock has fallen 26% year-to-date. 

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