Taysha has gathered the data it needs to start a conversation with FDA and EU regulators about the approval pathway for its first gene therapy, which the biotech hopes will become the first approved treatment for a rare neurodegenerative disease that leads to death by a patient's early twenties.
The biotech's gene therapy, dubbed TSHA-120, helped patients with the muscle-weakening disease giant axonal neuropathy, or GAN, improve on a motor function abilities test, Taysha said Monday. The biotech's stock rose nearly 8.5% to $7.78 per share as of 9:52 a.m. Eastern time.
GAN presents in children before age five through symptoms of motor weakness, frequent falls and unsteady gait.
TSHA-120 led to clinically meaningful and statistically significant improvement on the motor test, which assesses functional abilities of patients with neuromuscular diseases, across all three dose cohorts by year one as compared to natural history. The 12 patients showed a seven-point improvement in the change in rate of decline versus the natural history group, which declined eight points by year one. Clinically meaningful is considered a four-point change or greater.
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Taysha also said there was a 10-point improvement in the mean change from baseline in motor test score across all doses for patients observed at three years. One patient reached a five-year visit, at which time a 26-point improvement in change from baseline was observed.
The biotech hopes this data package will build the case for TSHA-120's filing in the U.S. and EU. The company now plans to engage with regulators "in order to discuss pathways for registration," according to RA Session, Taysha CEO, president and founder. Taysha will provide a regulatory update by the end of the second quarter, the biotech said in an investor presentation Monday.
The path to market in the U.S. could go one of three ways, the biotech said. Taysha could file for immediate approval if the FDA "agrees with the analytical comparability of commercial-grade material."
Or, the biotech might need to dose a few more patients to make that commercial-grade comparison, which is a similar approval pathway to Zolgensma, Novartis' spinal muscular atrophy gene therapy.
Taysha's most "unlikely" route is conducting a new pivotal trial, the company said in its slide presentation.
“In the interim, we are finalizing our commercial strategy with a focus on patient identification, disease awareness and payor engagement for the estimated 5,000 affected patients in addressable markets," said Session in a statement.
The therapy has the potential for $2 billion in "near-term commercial opportunity," the biotech said last year.
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The Dallas biotech acquired the worldwide exclusive rights to the gene therapy just last April. Taysha doled out $5.5 million upfront to an undisclosed GAN patient advocacy group that stands to receive up to another $19.3 million via biobucks, in addition to single-digit royalties on net sales.
Taysha is among a group of biotechs, pharmas and industry organizations going after rare diseases through the FDA and National Institutes of Health's Bespoke Gene Therapy Consortium, which is backed by $76 million in funding for five years.