Dallas, Texas – Taysha Gene Therapies touted positive early-stage data last month for its gene therapy to treat Rett syndrome, which has become the company’s main focus after cutting other programs and laying off 35% of its staff. If successful, the candidate for Rett syndrome has the capability to put Taysha in a billion-dollar market.
The early-stage data only show the results of four Rett patients from a Phase I/II trial on Taysha’s AAV9 gene transfer therapy TSHA-102, however. Taysha’s focus on Rett comes after a patient death was recorded in 2022 for its experimental gene therapy for Sandhoff and Tay-Sachs diseases. While the death was not attributed to the therapy itself, it still drove down the company’s stock price, and eventually, Taysha abandoned the program, throwing its resources into Rett.
If TSHA-102 does go the distance, the market could be a lucrative play for the Dallas-based biotech. With an estimated 16,600 to 25,800 patients in the U.S., the market totals an estimated $2.5 billion, according to an analyst report from Bank of Montreal Capital Markets. If everything goes according to plan, Taysha may have a solid opportunity to carve out a good slice of the Rett market—to the tune of around $1 billion at peak revenues in 2035, experts told BioSpace.
“There’s a clear need for something better that could give these patients a real chance at having a more normal life,” said Maury Raycroft, an equity analyst at Jefferies.
Taysha’s Push in Rett Syndrome
After the patient death in 2022, Taysha announced it would focus on targeting Rett and giant axonal neuropathy (GAN) but pause work on its other R&D efforts, and axed 35% of its workforce. In 2023, further setbacks hit Taysha as the FDA requested more patient dosing to support a Biological License Application for its GAN therapy, TSHA-120.
Finally, after a Type C meeting later that year, the company chose to halt all development of TSHA-120 and focus entirely on TSHA-102.
The trial data reported in June was split into two cohorts. The pediatric patients showed improvements in motor skills, communication, and a reduction in the rates of seizure, among other observations. The adults in the trial had similar results, with one patient having normal sleep for the first time in 20 years. No serious adverse events occurred during the trial, according to Taysha.
However, the results are not only early stage but involve a very small number of patients, Raycroft reminded BioSpace. In addition, investors’ feedback noted that the scales Taysha used did not show “clear trends” or clear consistency. Raycroft said that these scales are based on caregiver and clinician assessments, however, and he puts more weight on the clinicians’ findings. He sees this as a positive start for Taysha and believes that higher dose data should be available in the year’s second half. “I think the adult data is potentially even more meaningful, based on this update, because we’re seeing data after one year for one patient, and then half the year for the other patient, and both of those patients seem durable, at a minimum.”
The Future for Taysha
For smaller biotechs like Taysha, culling programs and eliminating employees may be necessary to preserve capital to get a product on the market, Raycroft said. He noted that the Rett candidate is Taysha’s best opportunity to get a product across the finish line, and it ultimately makes sense to prioritize and focus on it.
He noted that Reata Therapeutics made a similar play with Friedreich’s ataxia drug Skyclarys, which was approved by the FDA last year and eventually acquired by Biogen. The company previously discontinued other programs in its pipeline, including its candidate for chronic kidney disease, choosing to focus solely on getting Skyclarys across the finish line.
With its recent results, Taysha is looking to net more funds, recently announcing a public offering of over 14 million shares, which the company expects to bring around $75 million. In SEC documents, Taysha highlighted that the funds from the public offering would go toward the clinical, regulatory and manufacturing development of TSHA-102.
With Taysha, Raycroft said, “they’re focused on reducing their expenses. And making sure that every dollar they spend will be more relevant to advancing this Rett syndrome program because this is their best option at reaching that pinnacle.”
Tyler Patchen is a staff writer at BioSpace. You can reach him at [email protected]. Follow him on LinkedIn.