Dallas’ Taysha Gene Therapies Gets Worldwide Rights to Gene Therapy That Treats a Rare Neurodegenerative Disease

On the heels of a milestone year, which also happened to be the same as its official launch, Dallas-based Taysha Gene Therapies has secured the exclusive worldwide rights to a clinical-stage gene therapy program that treats a rare inherited genetic disorder.

The AAV9 gene therapy Taysha has acquired would be used for giant axonal neuropathy (GAN), which affects both the central and peripheral nervous systems. Now known as TSHA-120, the late-stage candidate is currently being evaluated in a Phase 1/2 trial for the treatment of GAN.

It’s a major breakthrough, especially considering there are currently no approved treatments or GAN.

The debilitating disease often causes death in patients by their late twenties. It’s caused by loss-of-function mutations in the gene coding for gigaxonin, and many children experience symptoms like progressive scoliosis, contractures, atrophy of the spinal cord, and more before the age of five.

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The U.S. Food and Drug Administration has given TSHA-120 rare pediatric disease and orphan drug designations for the treatment of GAN. The Phase 1/2 trial is being conducted by the National Institute of Neurological Disorders and Stroke (NINDS) division of the National Institutes of Health in collaboration with a patient advocacy group dedicated to finding cures for the severe genetic disorder.

TSHA-120 is intrathecally dosed, meaning that the drug is administered by an injection into the spinal canal. It’s the first successful in-human intrathecal gene transfer in the history of gene therapy, according to the Taysha team. That makes the clinical trial historic.

And, it already has ties to Dallas.

TSHA-120 was developed in a UT Southwestern lab by Dr. Steven Gray, Taysha’s chief scientific advisor and an associate professor in the Department of Pediatrics at UT Southwestern.

Gray said that preclinical results support the advancement of the gene therapy, and he’s thrilled Taysha is continuing such a meaningful program—one that has had an impact “across the entire gene therapy landscape and, most critically, on patients with GAN.”

“My work on the GAN program, which encompassed the scientific approach around the use of the AAV9 vector, intrathecal delivery, and HEK293 manufacturing, was the springboard for all of the other translational research initiatives in my lab,” he said. “With its expertise in clinical, regulatory and manufacturing domains, Taysha has the potential to rapidly advance TSHA-120, and if approved, enable expeditious access for physicians and patients impacted by GAN.”

TSHA-120 aligns with the work Taysha was founded to do. The local biotech is a patient-centric gene therapy company aims to develop and commercialize AAV-based (adeno-associated virus) gene therapies for the treatment of monogenic diseases of the central nervous system. Taysha focuses on CNS diseases in both rare and large patient populations.

And since it emerged from stealth in 2020, the company has made some progressively big moves.

Taysha got an explosive start with $125 million in Series A and B funding, followed by more than $157 million and a September IPO. On its first day of trading, Taysha saw a 20 percent rise in its stock price, despite launching during a global pandemic. From there, Founder, President, and CEO RA Session II and his team have stayed focused on their primary goal: wiping out monogenic disorders of the CNS.

According to Session, TSHA-120 will be immediately value-accretive for Taysha. The clinical data already gathered is a “clear validation” of the team’s scientific approach, and points to their existing product development pipeline.

“Collectively, these key parallels enable Taysha to leverage synergies across its core competencies to efficiently develop and commercialize TSHA-120,” he said in a news release. “We look forward to expeditiously working with the regulatory agencies on a path forward to approval of TSHA-120, and in parallel, accelerating the build-out of our commercial infrastructure to support patient identification, payor engagement and product distribution””

So far, 14 patients have been dosed with one of four dose levels of TSHA-120. Phase 1/2 clinical data showed the clear arrest of disease progression and long-term durability at therapeutic dose levels in GAN patients, Taysha said.

TSHA-120 could help an estimated 2,400 GAN patients across the U.S. and Europe. That represents a potential near-term commercial opportunity of more than $2 billion, according to Session.

That also means that it transforms Taysha into a sustainable pivotal-stage gene therapy company.

“This program further supports our approach to treating monogenic diseases of the CNS and may enable us to pursue proof-of-concept for our redosing platform,” Suyash Prasad Taysha’s chief medical officer and head of Research and Development, said in a statement. “We are very encouraged by TSHA-120’s halting effect on disease progression at therapeutic dose levels and long-term durability of effect in patients living with GAN.”

Up next, Taysha expects to highlight the initial Phase 1/2 clinical data in an R&D Day this June. The company is currently planning to engage regulatory agencies in the United States, Europe, and Japan as soon as possible.

In exchange for granting Taysha the global rights to TSHA-120, the GAN patient advocacy group will receive an upfront payment of $5.5 million. It will also be eligible to receive clinical, regulatory, and commercial milestones of up to $19 million, as well as a low, single-digit royalty on net sales upon commercialization.

“We are thrilled that Taysha will be advancing TSHA-120 through clinical development as the first potential disease modifying treatment for GAN,” Carsten Bönnemann, senior investigator and chief of the Neuromuscular and Neurogenetic Disorders of Childhood Section at the NINDS, part of the NIH, said. “With TSHA-120’s compelling tolerability profile and data demonstrating dose dependent disease modification in patients treated in the Phase 1/2 trial, we believe this therapy holds incredible promise for patients with GAN around the world.”