Clinical trials

Stargardt disease type 1 (STGD1) is a rare genetic eye condition that causes progressive vision loss, often beginning in childhood or adolescence. It is the most common form of inherited macular degeneration and can lead to legal blindness. STGD1 is caused by mutations in the ABCA4 gene, which normally helps clear waste from the photoreceptor cells in the retina. When ABCA4 gene doesn't function properly, toxic substances like A2E accumulate and damage the retinal pigment epithelium (RPE), leading to vision loss. There are currently no approved treatments for STGD1. HG005 is an investigational gene therapy designed to deliver a healthy copy of the ABCA4 gene to the retina. Because the gene is too large to fit into a single AAV (adeno-associated virus) vector, HG005 used two AAV vectors that work together in retinal cells to produce the full-length, functional ABCA4 protein. The goal of HG005 is to restore normal waste removal, protect retinal cells from further damage, and slow or stop vision loss.

Age-related macular degeneration (AMD) is a progressive disease leading to severe and irreversible vision loss of which the neovascular AMD (nAMD) accounted for 90% blindness in AMD. nAMD is primarily driven by the perturbation of vascular endothelial growth factor (VEGF). VEGF overexpression leads to abnormal growth of choroidal neovascularization (CNV), which is a hallmark of AMD. Although anti-VEGF agents are effective in treating nAMD, long-term efficacy decreases over time due to the need for repeated injections impacting patient compliance with treatment regimen while patients still may lose vision during the 7th or 8th year of treatment. These frequent intravitreal injections can increase the risk of complications, including submacular hemorrhage, intraocular hypertension, inflammation, and retinal detachment. Furthermore, there are up to 46% of nAMD patients using anti-VEGF agents who have shown poor response or have developed tachyphylaxis with anti-VEGF therapies. HG202 is a CRISPR/Cas13 RNA-editing therapy packaging novel high-fidelity Cas13 technology using one single AAV vector to partially knock-down the expression of VEGFA and thus inhibit CNV formation in AMD patients who are either responsive or non-responsive to anti-VEGF agents. The long-term, stable delivery of HG202 following a one (1) time gene-editing therapy treatment for nAMD could potentially reduce the frequent injection treatment burden of currently available therapies AND treat nAMD patients who are non-responsive to anti-VEGF therapies and have no treatment.

Methyl-CpG binding protein 2 (MECP2) is a dosage-sensitive, X-linked gene critical for central nervous system development and functional maintenance, which gain-of-function causes MECP2 duplication syndrome (MDS). Affecting primarily in males, this disorder is characterized by severe intellectual disability, motor dysfunction, infantile hypotonia, epilepsy, respiratory tract infections, and premature death before 25 years of age with no curative therapy. HG204 is a CRISPR RNA-editing therapy packaging novel high-fidelity Cas13Y (hfCas13Y) technology, using one single adeno-associated virus (AAV) vector to target and knock down MECP2 mRNA in the brain. Preclinical studies showed that a single intracerebroventricular injection of HG204 persistently decreased MECP2 mRNA and MECP2 protein in the cortex of the MDS mice, reversed the abnormal motor and social phenotypes, and significantly prolonged survival in MDS mouse models.

Age-related macular degeneration (AMD) leads to severe and irreversible vision loss, while neovascular AMD (nAMD) accounts for 80-90% of AMD blindness. Current anti-VEGF therapies are the standard of care, but these therapies require life-long repeated intraocular injections. These frequent intravitreal injections increase the risk of complications, including submacular hemorrhage, intraocular hypertension, inflammation, and retinal detachment. Therefore, repeated treatments for nAMD place a substantial burden on healthcare systems, patients, and their caregivers. Additionally, approximately 25-35% of individuals with aggressive nAMD show suboptimal responses to the anti-VEGF therapies, experience treatment-extended failure, or require intensive, frequent intraocular injections, and do not prevent irreversible vision loss. HG202 is a CRISPR/Cas13 RNA-editing therapy delivered through one single AAV vector to partially knock down the expression of VEGFA and thus inhibit CNV formation in AMD. The long-term, stable delivery of HG202 following a one-time gene-editing therapy treatment for nAMD may potentially reduce the frequent injections and the potential risks of currently available anti-VEGF therapies since it does not rely on the long-term expression of anti-VEGF antibodies.

The purpose of the study is to determine whether HG004 as gene therapy is safe and effective for the treatment of Leber Congenital Amaurosis caused by mutations in RPE65 gene.