FDA Grants Rare Pediatric Disease Designation to Taysha Gene Therapies’ Therapy for SURF1-Associated Leigh Syndrome

Rare Daily Staff

The U.S. Food and Drug Administration granted Rare Pediatric Disease designation to Taysha Gene Therapies’ experimental AAV9-based gene therapy TSHA-104 for the treatment of SURF1-associated Leigh syndrome, a rare neurologic disorder.

Leigh syndrome usually presents in the first year of life. It is characterized by progressive loss of mental and movement abilities that can result in death within two to three years. SURF1 deficiency is a monogenic mitochondrial disorder and is the most common cause of cytochrome c oxidase deficient Leigh syndrome. Approximately 10 percent to 15 percent of people with Leigh syndrome have a SURF1 mutation.

“We have now obtained rare pediatric disease and orphan drug designations in multiple gene therapy programs, which we believe will allow us to work more effectively with the FDA as we advance our broad portfolio,” said RA Session II, president, CEO and founder of Taysha.

Taysha expects to apply to begin human clinical trials to the FDA for TSHA-104 in 2021.

“Being diagnosed with a mutation in the SURF1 gene is a truly devastating event for families,” said Kasey Woleben, founder of Cure SURF1 Foundation. “Taysha’s commitment to developing a gene therapy for SURF1 deficiency is greatly welcomed by the patient community and has the potential to save the lives of children afflicted with this progressive disorder.”

Taysha has secured rare pediatric disease designation and orphan drug designation for multiple programs, including GM2 gangliosidosis, CLN1, Rett syndrome and now SURF1. In addition to these designations, the company also has fast track status for the CLN1 program.

The FDA grants Rare Pediatric Disease designation for serious or life-threatening diseases with manifestations in individuals aged from birth to 18 years, including access to the FDA’s expedited review and approval process. The designation makes TSHA-104 eligible for a Rare Pediatric Disease Priority Review voucher upon approval of the therapy by the FDA.

The vouchers can be used to reduce the time of an FDA new drug approval review to six months from ten months. The vouchers are potentially lucrative because they are transferable. Most recently, Sarepta sold its priority review voucher to Vifor Pharma $111 million in February 2020.

The voucher program was due to expire at the end of September but Congress provided a short-term extension of the program. According to the current statutory sunset provisions, after December 11, 2020, FDA may only award a voucher for an approved rare pediatric disease product application if the sponsor has rare pediatric disease designation for the drug, and that designation was granted by December 11, 2020. After December 11, 2022, FDA may not award any rare pediatric disease priority review vouchers.

Going forward, requests for rare pediatric disease designation submitted will be reviewed in a timely manner but the FDA’s previous 60-day response time no longer applies.

Photo: RA Session II, president, CEO and founder of Taysha