Narrowing Focus to Rett and GAN, Taysha is Reducing Workforce by 35%

Taysha CEO RA Session II/Courtesy Obiosh

In a fourth-quarter corporate update, Taysha Gene Therapies announced that it will focus its efforts on clinical programs targeting Rett Syndrome and giant axonal neuropathy (GAN). Homing in on these programs will result in the pausing of other clinical research and development and a 35% reduction in its workforce. 

Rett Syndrome and GAN are monogenic diseases of the central nervous system. Rett Syndrome results from a mutation in the MECP2 gene on the X chromosome and occurs worldwide in one of every 10,000 female births. The neurological disorder causes a broad spectrum of symptoms, including loss of speech, mobility and muscle tone and breathing issues. GAN is caused by an abnormality in a gene that encodes for the gigaxonin protein found on chromosome 16. The disorder also impacts mobility and motor abilities and can cause seizures and skeletal abnormalities.  

Taysha is developing therapeutic TSHA-102 for Rett Syndrome, a self-complementary, intrathecally delivered AAV9 gene replacement therapy that regulates transgene expression genotypically on a cell-by-cell basis. TSHA-102 is the first and only gene therapy being developed for Rett Syndrome and has received the Orphan Drug and Rare Pediatric Disease designations from the U.S. Food and Drug Administration (FDA). 

Preclinical data has been positive for the use of TSHA-102. In mice models studied, a one-time injection of the therapeutic significantly increased survival and improved body weight, motor function and respiratory assessments. Additionally, no toxicity was observed from transgene overexpression, and no adverse tissue was found at the end of the study. 

For the treatment of GAN, Taysha is developing TSHA-120, which utilizes AAV9 gene therapy as well. TSHA-120 is designed to deliver a functional copy of the gene that is mutated in people with GAN to both the central and peripheral nervous systems. The therapeutic has earned Orphan Drug and Rare Pediatric Disease designations from the FDA. 

TSHA-120 has reported positive clinical efficacy and safety in cohorts treated with the drug. Efficacy data from the high dose cohort showed clinically meaningful and statistically significant improvement on assessments of motor ability. The therapeutic has also demonstrated efficacy in long-term studies showing an average 10-point improvement in motor assessments by year three after partaking in the therapy.  

“We are sharpening our strategic focus to prioritize key value-driving registration-directed programs in GAN, which has an estimated addressable patient population of 5,000 worldwide, and Rett syndrome, which affects over 350,000 patients worldwide,” noted RA Session II, president, founder and CEO of Taysha. “To increase operational efficiency, activities for other ongoing clinical programs will be minimized and all additional research and development will be paused. As a result, we have reduced our workforce by approximately 35 percent. Our strategic pipeline prioritization, along with existing cash and financing under our current debt facility is expected to extend cash runway into the fourth quarter of 2023.” 

In addition to a reduction in workforce, Taysha will also pause all additional research and development activities to increase operational efficiency in its lead programs. The company plans to continue clinical development for a therapeutic intended to treat CLN7 Batten Disease, a collection of disorders that affect the nervous system. Development of the therapeutic is in collaboration with UT Southwestern and funded by the Children’s Medical Center Foundation. 

Taysha is anticipated to provide a regulatory update for TSHA-120 by mid-2022 and share data from a first-in-human Phase I/II trial for TSHA-102.