FDA Grants Rare Pediatric Disease Designation to Polaryx’s Treatment for GM2 Gangliosidosis

Rare Daily Staff

The U.S. Food and Drug Administration granted Rare Pediatric Disease Designation to Polaryx Therapeutics’ PLX-300 for the treatment of GM2 gangliosidosis.

GM2 gangliosidosis, also known as Tay-Sachs disease and Sandhoff disease, is an ultra-rare and fatal pediatric neurodegenerative disorder caused by defects in key lysosomal enzymes that lead to abnormal accumulation of gangliosides. This results in progressive neurodegeneration, seizures, loss of mobility, hearing, and vision, and early death. There is no cure for these diseases and the only treatment is supportive care.

The FDA also granted PLX-300 Orphan Drug designation. PLX-300 is currently in preclinical studies to enable entry into phase 1/2 studies in near future.

“These designations clearly demonstrate the translational excellence of the PLX-300 from bench to bedside,” said Hahn-Jun Lee, president and CEO of Polaryx Therapeutics.

PLX-300 is a novel, small molecule found in many plants as a deaminated product of phenylalanine. It is widely used as a spice or flavoring material for food. It activates PPARα, which enhances production of transcription factor EB (TFEB). TFEB then binds to the promoter of genes involved in lysosome biogenesis and activates their production. PLX-300 also has additional activities, such as reducing inflammation and preventing cell death.

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 PLX-300 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, Eiger BioPharmaceuticals sold its priority review voucher for $95 million in November 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, submitted requests for rare pediatric disease designation will be reviewed in a timely manner but the FDA’s previous 60-day response time no longer applies.

Photo: Hahn-Jun Lee, president and CEO of Polaryx Therapeutics