FDA Grants RMAT to Orca Bio’s Cell Therapy and RPD to Taysha Gene Therapies’ Gene Therapy

Rare Daily Staff

The U.S. Food and Drug Administration granted separate designations designed to accelerate therapeutic development to two experimental therapies of two rare disease drug developers, Orca Bio for a cell therapy and Taysha Gene Therapies for a gene therapy.

The FDA granted Regenerative Medicine Advanced Therapy and Orphan Drug designations to Orca Bio’s experimental allogeneic cell therapy for patients with blood cancers who are eligible for a hematopoietic stem cell transplant.

For many patients with blood cancers, blood stem cell transplants from donors are the only hope for a cure. However, conventional transplants are often associated with cancer relapse and complications such as graft-versus-host disease (GvHD)—a condition in which immune cells from the donor attack the patient’s healthy cells, leading to organ failure and even death. Orca-T is a precisely controlled formulation of hematopoietic stem cells and T cells that aims to improve outcomes for these patients.

“The RMAT and ODD for Orca-T is uplifting news for patients with various blood cancers including acute myeloid leukemia, acute lymphoid leukemia, myelodysplastic syndrome and myelofibrosis,” said Ivan Dimov, CEO and co-founder of Orca Bio. “We now have the opportunity to work closely with the FDA to open potential ways to support accelerated approval.” Clinical data from the ongoing Orca-T trial will be presented at the 62nd American Society of Hematology Annual Meeting later this year.

The FDA also granted Rare Pediatric Disease and Orphan Drug designations to Taysha Gene Therapies’ AAV9-based gene therapy, TSHA-102, in development for the treatment of Rett syndrome. Taysha anticipates that it will submit an Investigational New Drug (IND) application for TSHA-102 to the FDA in 2021.

Rett syndrome is one of the most common genetic causes of severe intellectual disability worldwide, with a prevalence of more than 25,000 cases in the United States and the European Union. It is an X-linked disease that primarily occurs in females, but it can be seen very rarely in males. It is usually recognized in children between six to 18 months of age as they begin to miss developmental milestones or lose abilities they had developed. Individuals with Rett syndrome also show symptoms that include loss of speech, loss of purposeful use of hands, loss of mobility, seizures, cardiac impairments, breathing issues and sleep disturbances. There are currently no approved therapies that address the underlying cause of the disorder.

Rett syndrome is caused by mutations in the MECP2 gene. TSHA-102 is designed to deliver a healthy version of the MECP2 gene as well as the miRNA-Responsive Auto-Regulatory Element, miRARE, platform technology to control the level of MECP2 expression.

“Obtaining these designations is a validation of decades-long work to identify and optimize a potential gene therapy treatment for this devastating disease,” said RA Session II, president, CEO and founder of Taysha. “We are also excited to advance our miRARE platform whereby regulated expression of a transgene is possible on a cellular basis. The miRARE platform has broad applicability across a wide range of monogenic CNS disorders where there is a need to control transgene expression.”

ODD status is granted for therapies that address rare diseases affecting fewer than 200,000 people in the United States. If a therapy with ODD receives the first FDA approval for the designated condition, it is eligible for 7-year market exclusivity.

RMAT is a dedicated program designed to expedite the development of new regenerative therapies, including cell therapies that have the potential to treat life-threatening medical conditions. Cell therapies granted the RMAT designation also receive the benefits of fast track and breakthrough therapy designations. These advantages include early guidance from the FDA to steer manufacturing and clinical development, such as determination of intermediate endpoints to potentially support accelerated approval.

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 these experimental therapies 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