Second Gene Therapy from MeiraGTx Granted Rare Pediatric Disease Designation

This morning, the Offices of Orphan Products Development and Pediatric Therapeutics of the U.S. Food and Drug Administration (FDA) have granted rare pediatric disease designation to MeiraGTx’s A002 (ZZV2/8-hCARp.hCNGB3).

The gene therapy product candidate is intended for the treatment of patients with achromatopsia (ACHM) because of mutations in the CNGB3 gene.

Achromatopsia is a recessively inherited condition that results in complete color blindness and visual acuity. It is caused by a lack of cone photoreceptor function, and can also lead to disabling hypersensitivity to light, or photophobia, and involuntary eye movements, also known as pendular nystagmus.

Per MeiraGTx, ACHM affects approximately 1 in 33,000 people in the U.S. and four different genetic mutations may cause it: 50% of patients carry mutations in the CNGB3 gene, and 25% in the CNGA3 gene. Children with CNGB3-related achromatopsia have profound sight impairment from birth or early infancy, and there aren’t currently any therapies approved to treat the condition.

A002, an adeno-associated virus (AAV) is being developed to deliver a codon-optimized hCNGB3 cDNA to the back of the eye for expression in cone photoreceptors.

“We are excited to be making such good progress in dosing patients in our ongoing Phase I/II CNGB3 clinical trial,” said Zandy Forbes, Ph.D., President and CEO of MeiraGTx in a press release.

MeiraGTx has dosed 8 patients in an open label, multi-center Phase 1/2 dose escalation trial of the gene therapy in patients diagnosed with achromatopsia due to biallelic mutations in CNGB3. The trial is currently treating patients in the highest of 3 dose cohorts and safety is the primary endpoint.

Secondary endpoints for the trial include improvement in visual function including assessment of photophobia/photoaversion, retinal function, retinal structure and quality of life (QOL) measures.

If A002 is approved by the FDA for this indication, Meira GTx will be eligible to receive a Priority Review Voucher, which can be used on any of the company’s future drugs to reduce the FDA review time by 4 months. It can also be sold.

When awarded a voucher, small biotech companies sometimes sell it to larger pharmaceutical companies. Last year, Sarepta sold its voucher for $125 million to Gilead Sciences.

In December, the company was granted rare pediatric designation for A001 (AAV2/5-OPTIRPE65) for the potential treatment of certain patients with Lever Congenital Amaurosis. "With the receipt of our second rare pediatric disease designation in just two months, we have significant momentum for our ocular gene therapy pipeline as we begin 2018," continued Forbes.

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