U.S. FDA AWARDS BOTH RARE PEDIATRIC DISEASE AND ORPHAN DRUG DESIGNATIONS TO HG204, A CRISPR RNA-EDITING THERAPY, FOR THE TREATMENT OF MECP2 DUPLICATION SYNDROME

• Orphan Drug Designation (ODD) is a status that provides 7 years of post-approval protection and exemption from filing fees
• Rare Pediatric Disease Designation (RPDD) qualified the Sponsor at the time of registration for a salable, transferable priority review voucher which can be used to speed up the approval process for another drug candidate
• HG204 is the world first CRISPR RNA-editing therapy for the treatment of MECP2 duplication syndrome granted both RPDD and ODD by the U.S. FDA

SHANGHAI and CLINTON, N.J., Oct. 31, 2023 /PRNewswire/ -- HuidaGene Therapeutics (辉大基因，"HuidaGene"), a global clinical-stage biotechnology company focused on developing CRISPR-based programmable genomic medicines, today announced the U.S. Food and Drug Administration (FDA) had granted both the Rare Pediatric Disease Designation (RPDD) and Orphan Drug Designation (ODD) to HG204 for the treatment of MECP2 duplication syndrome (MDS), a rare and fatal childhood neurodevelopmental disorder for which there is no treatment.

"We are delighted to have been awarded both RPDD and ODD for HG204, the world's first novel CRISPR RNA-editing therapy independently-developed by HuidaGene for the treatment of the rare and fatal MDS genetic disease, by the U.S. FDA," said Alvin Luk, Ph.D., M.B.A., C.C.R.A., Co-founder and Chief Executive Officer of HuidaGene. "Although there is currently no clinical trial evaluating MDS, this is a sign of recognition for MDS and raises hopes for children and teens with this fatal, devastating disorder. I would like to say a big thank you to our MDS team for pioneering the development of this potential drug and for their great contribution in communicating with FDA, without whom none of this would have been possible. We very much hope that HG204 can make a difference to children and families affected by MDS, and we will be working closely with clinicians, researchers, and FDA to determine the optimal way to move the drug forward."

The FDA defines rare pediatric diseases as rare diseases (with fewer than 200,000 cases in the United States) that are serious or life threatening and primarily affect individuals aged under 18. When the FDA awards rare pediatric disease designation (RPDD), the Sponsor of the trial firstly is granted a 6-months accelerated review of the drug candidate irrespective of indication, and which may be sold to another company. In such case the length of the approval procedure is also considerably shortened, generally taking just 6 months instead of the usual 12 months, which gives a very high value of this priority review voucher. The legal status of orphan drug designation (ODD) in the United States was provided by the Orphan Drug Act, qualifying the Company for accelerated review of its drug candidate for approval upon the registration – in an indication with a prevalence in the United States of less than 200,000 cases. It also supports with the FDA regulatory process and at least 7 years of post-approval protection, as well as exemption from filing fees than normally have to be paid to the FDA.

"This is HuidaGene's second program that has been granted both RPDD and ODD by the U.S. FDA, highlighting the potential clinical value of this innovative therapy for MDS, a childhood neurodevelopmental disease," said Xuan Yao, Ph.D., Co-founder, President and GM for Greater China of HuidaGene. "MDS is a rare and fatal childhood disease with the progressive of neurological regression such as loss of motor skills and speech. Data from our preclinical studies have shown that HG204, an RNA editing therapy based on CRISPR/Cas13Y independently-developed by HuidaGene to target MECP2 mRNA, can effectively reduce MECP2 expression levels, restore motor function, and significantly prolong lifespan in the MDS mouse models. We are fully committed to our mission of advancing HG204 into the clinic to solve the urgent clinical needs of this hereditary pediatric disease and delivering transformative CRISPR-based genome medicines to patients worldwide."

About MECP2 Duplication Syndrome
Methyl-CpG binding protein 2 (MeCP2) duplication syndrome (MDS) is a rare, fatal childhood neurodevelopmental disorder with an estimated live birth prevalence in males of 1 per 150,000. MDS is one of the most common sub-telomeric genomic rearrangements in males, accounting for about 1-2% of X-linked cases of intellectual disability. MDS which is caused by the duplication or triplication of the MECP2 gene manifests predominantly in boys and is characterized by infantile hypotonia, developmental delay, intellectual disability, anxiety, loss of motor skills and speech, epilepsy, recurrent respiratory tract infections and shortened lifespan, with death often occurring before the age of 25 years. There are no approved disease-modifying therapies for MDS and current treatments for MDS include symptom management and supportive care.

About HG204
HG204 (AAV-hfCas13Y-gMECP2) is developed using a single adeno-associated viral (AAV) vector delivering a novel CRISPR/high-fidelity Cas13Y (hfCas13Y) and gRNAs targeting MECP2 (gMECP2). HG204 is stably expressed in brain regions of mice and monkeys where the pathological changes of MDS mainly occur. Our extensive preclinical studies using AAV-hfCas13Y-gMECP2 in humanized MDS mouse model demonstrated significant reduction of MeCP2 protein and reversal its disease features.

This HG204 therapy is designed to treat MDS patients.

About HuidaGene - 辉大基因
HuidaGene Therapeutics (辉大基因) is a global clinical-stage biotechnology company focusing on discovering, engineering, and developing novel gene-editing tools and gene therapies to rewrite the future of genomic medicine. Based in Shanghai and New Jersey, HuidaGene is committed to addressing patients' needs globally with various preclinical therapeutic programs covering ophthalmology and neurology. We are currently advancing clinical programs of HG004 in inherited retinal disease caused by RPE65 mutations (which has been granted both ODD and RPDD by U.S. FDA), HG202 CRISPR/Cas13Y RNA-editing in neovascular age-related macular degeneration (nAMD), and our preclinical pipeline, including programs HG301 CRISPR/Cas12 DNA-editing in retinitis pigmentosa, HG204 CRISPR/Cas13Y RNA-editing in neurodevelopmental disease of MECP2 duplication syndrome (MDS) (which has been granted both RPDD and ODD by U.S. FDA), and HG302 CRISPR/Cas12 DNA-editing in neuromuscular diseases of Duchenne muscular dystrophy (DMD) etc. Company's CRISPR-based therapeutics offer the potential to cure patients with life-threatening conditions by repairing the cause of their disease. HuidaGene is committed to transforming the future of genome-editing medicine.

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