Graybug Announces Pipeline Expansion, Current Cash Expected to Deliver Three Clinical Readouts in 2023

• Phase 2 trial with optimized formulation in wet AMD expected to start in fourth quarter of 2022
• Phase 1 trial in glaucoma expected to commence in first quarter of 2023
• Acquired corneal gene therapy program; Phase 1/2a data expected in fourth quarter of 2023
• New programs for Retinitis Pigmentosa and Geographic Atrophy
• Current cash expected to fund planned operations into fourth quarter of 2023
• Graybug to host virtual Investor R&D Day today, March 30, 2022, beginning at 11 a.m. ET

BALTIMORE, March 30, 2022 (GLOBE NEWSWIRE) — Graybug Vision, Inc. (Nasdaq: GRAY), a clinical-stage biopharmaceutical company focused on developing transformative medicines for the treatment of ocular diseases, today announced a strategic update on its pipeline programs GB-102 in wet age-related macular degeneration (wet AMD), GB-401 in primary open-angle glaucoma (POAG), as well as its newly acquired assets in corneal disease (GB-501), inherited retinal diseases (GB-601), and geographic atrophy (GB-701).

“We are very excited to move GB-102 into a Phase 2 clinical trial in wet AMD in the fourth quarter of 2022, while expanding our pipeline to address additional vision-threatening retinal and corneal diseases with high unmet patient needs. We plan to use our current cash to advance GB-102, GB-401 and GB-501 to clinical readouts in 2023,” said Fred Guerard, PharmD, Chief Executive Officer of Graybug.

GB-102 for wet AMD: Graybug plans to proceed with a Phase 2 clinical trial of an optimized formulation of GB-102 in wet AMD patients following successful demonstration of improved performance in an extensive battery of novel in vitro stress tests. This decision, supported by a significantly more favorable competitive landscape following recent readouts of other long-acting vascular endothelial growth factor (VEGF) inhibitors, is anticipated to result in a six-month data readout available in the third quarter of 2023. “We are confident that our optimized formulation, together with modified patient inclusion criteria, will demonstrate efficacy similar to the current standard of care while also maintaining the unprecedented duration of up to 12 months observed in the ALTISSIMO trial,” said Parisa Zamiri, MD, PhD, Chief Medical Officer of Graybug.

GB-401 for POAG: In glaucoma, poor patient compliance with eye drops frequently results in suboptimal control of intraocular pressure (IOP), and degeneration of the optic nerve, leading to irreversible vision loss. GB-401 is a potentially first-in-class implant formulation containing a novel prodrug of timolol injected intravitreally with a proprietary applicator, targeting twice-yearly treatment. Initiation of a Phase 1 trial with GB-401 is planned for the first quarter of 2023, with safety and efficacy data expected to be available in the second quarter of 2023.

GB-501 for MPS1 Corneal Clouding: Graybug recently acquired RainBIO, a start-up company based in North Carolina, that developed a first-in-class gene therapy for mucopolysaccharidosis type 1 (MPS1), an inherited lysosomal storage disorder with very high prevalence of corneal clouding despite existing systemic therapies (enzyme replacement or hematopoietic stem cell transplant). GB-501 received Orphan Drug Designation from the FDA and is eligible for a Priority Review Voucher upon approval. Preclinical studies in a dog model of MPS1 demonstrated complete and sustained clearing of the cornea in all dogs, regardless of disease severity, in less than a month following a single intrastromal injection. Two-year animal data support the potential for GB-501 to cure corneal clouding and restore vision in MPS1 patients. All patients required for the Phase 1/2a trial have been identified, IND submission is expected in the second quarter of 2023, and the data readout is expected in the fourth quarter of 2023.

GB-601 for Inherited Retinal Diseases: Inherited retinal disorders such as retinitis pigmentosa, Leber’s congenital amaurosis, and Stargardt’s disease are the consequence of over 280 genetic mutations. To date, only one drug has been approved to address a single mutation (RPE65), which accounts for a very small fraction of IRDs, leaving the vast majority of patients without therapeutic options. Graybug recently acquired a portfolio of novel cGMP analogs, supported by a well-characterized mode of action and preclinical data in established RP disease models, from Mireca Medicines GmbH, a German preclinical start-up company. Graybug is developing these cGMP analogs as first-in-class, mutation-agnostic long-acting therapeutics to treat a majority of patients with these diseases.

GB-701 for Geographic Atrophy: Geographic atrophy (GA) represents a significant unmet medical need with over five million patients worldwide suffering from this late-stage, age-related macular degeneration for which there is currently no FDA approved treatment. Recent clinical trials have indicated that targeting the complement pathway is suitable for slowing disease progression, but these investigational therapies require up to 12 injections per year. Graybug and Insilico Medicine, a clinical-stage, end-to-end artificial intelligence (AI)-drug discovery company, recently formed a strategic partnership to leverage Insilico’s AI-driven small molecule discovery platform with Graybug’s unique ocular drug delivery technologies enabling Graybug to develop a sustained-release, locally administered ocular formulation of a potent factor B inhibitor as a potential treatment for this vision-threatening disease.

Virtual R&D Day Webcast and Conference Call

Graybug’s management will host a virtual R&D Day webcast and conference call today beginning at 11 a.m. ET. To register, please sign up here. In addition, registration for this event and access to the webcast will be made available in the Investors and Media section of the company’s website at https://investors.graybug.vision/news-events/events-presentations, along with an archived replay following the live event. Attendees may also participate by dialing (844) 955-2748 (domestic) or (929) 517-0407 (international) and entering the conference ID# 9785187.

About Wet Age-Related Macular Degeneration (wet AMD)

Wet AMD is one of the most common retinal diseases, leading to vision decline caused by excess VEGF. VEGF is a protein produced by cells that stimulates the formation of abnormal new blood vessels behind the retina, called choroidal neovascularization. The leakage of fluid and protein from the vessels causes retinal degeneration and leads to severe and rapid loss of vision. Early intervention is essential to treat wet AMD. The prevalence of wet AMD in the United States is estimated at 1.5 million people and approximately 25 million people are affected by wet AMD worldwide.

About Primary Open Angle Glaucoma (POAG)

Glaucoma is an optic neuropathy that is characterized by the progressive degeneration of the optic nerve. It is a leading cause of irreversible vision loss affecting approximately 76 million people worldwide and 2.7 million people in the US. POAG is the most common type of glaucoma. As glaucoma progresses slowly and causes few symptoms, patients often do not adhere to their medication regimens as prescribed until the disease has progressed to the point of significant vision loss. As a result, despite the availability of medication to treat glaucoma, progressive visual loss and blindness still often occur.

About Corneal Clouding in Mucopolysaccharidosis Type 1 (MPS1) Patients

MPS1 is a rare, autosomal-recessive lysosomal storage disease caused by a deficiency of alpha-L-iduronidase (IDUA) affecting 1 in 100,000 people worldwide. It manifests as a progressive, life-threatening, multi-system disease that, in its most severe form, results in fatality in late childhood. While enzyme replacement therapy (ERT) and hematopoietic stem cell transplants (HSCT) have greatly increased life expectancy, these systemic treatments are unable to reach the cornea to prevent clouding, and the resulting loss of vision impacts more than 90% of MPS1 patients. Currently, no cure exists to address MPS1 corneal clouding.

About Inherited Retinal Diseases (IRDs)

Many hereditary diseases affect the retina and can result in severe vision impairment or blindness. The most common IRDs are caused by a genetic defect in a single gene, out of more than 280 possible genes, which compromises the viability of photoreceptors and leads to photoreceptor cell death. Adult-onset retinitis pigmentosa (RP) is the most common IRD, with a worldwide prevalence of approximately 1 in 4,000 people. A genetically related disease, Leber’s congenital amaurosis (LCA) has a prevalence of around 1 in 30,000 people and onset occurs in early childhood. Stargardt’s disease is the most commonly inherited retinal disease in children and adults with an estimated prevalence of 1 in 10,000 people in the United States. The death of photoreceptors due to IRDs results in permanent vision loss or blindness, and all but one of these diseases are still untreatable today.

About Geographic Atrophy (GA)

GA is an advanced form of dry age-related macular degeneration. It affects more than five million people globally, and more than 100,000 new cases are diagnosed each year. GA is a devastating blinding disease without any approved treatment currently available to prevent its onset or slow down its progression.

About Graybug

Graybug is a clinical-stage biopharmaceutical company focused on developing transformative medicines for ocular diseases. The company’s diversified portfolio is designed to treat vision-threatening diseases of the retina, optic nerve, and cornea, by either maintaining effective drug levels in ocular tissues for long periods of time, using innovative technologies, such as injectable sustained-release formulations, or by curing diseases with gene therapies. Graybug’s most advanced drug candidate, GB-102 is a microparticle formulation of a pan-VEGF inhibitor, sunitinib, for the treatment of wet age-related macular degeneration designed for a twice-per-year intravitreal injection. GB-102 has the potential to also benefit patients with diabetic retinopathy. GB-401 is a first-in-class implant formulation containing a novel prodrug of timolol for the treatment of primary open angle glaucoma (POAG) designed for a twice-per-year intravitreal injection with a proprietary applicator. GB-501 is an adeno-associated virus (AAV) gene therapy with Orphan Drug Designation (ODD) and Rare Pediatric Disease Designation (RPDD) to treat corneal clouding caused by mucopolysaccharidosis type 1 (MPS1), a lysosomal storage disorder. GB-601 is being developed as a long-acting formulation of a novel cGMP analog to address hereditary retinal diseases like retinitis pigmentosa, a group of genetic disorders that involve a loss of cells in the retina. GB-701 is being developed as a long-acting formulation of a potent factor B inhibitor targeting the complement cascade which plays a role in AMD. Founded in 2011 based on technology licensed from the Johns Hopkins University School of Medicine, Graybug has offices in Redwood City, California and in Baltimore, Maryland. For more information, please visit www.graybug.vision.

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995 including, but not limited to, statements regarding the company’s clinical pipeline, its ability to advance GB-102, GB-401, GB-501, GB-601, GB-701 or any future product candidate through preclinical or clinical development, its ability to initiate clinical trials, achieve its anticipated milestones within the timing outlined above or at all, its ability to conduct planned operations within the evolving constraints arising from the COVID-19 pandemic, accurately predict the timing or magnitude of its future cash requirements, the resulting depletion of its cash resources, and the timing, cost, and results of its clinical trials. Forward-looking statements are subject to risks and uncertainties that may cause the company’s actual activities or results to differ significantly from those expressed in any forward-looking statement, including risks and uncertainties described under the heading “Risk Factors” in the company’s annual report on Form 10-K filed for the year ended December 31, 2021, in its quarterly reports on Form 10-Q, and in the other reports the company files from time to time with the Securities and Exchange Commission. These forward-looking statements speak only as of the date of this press release, and the company undertakes no obligation to revise or update any forward-looking statements to reflect events or circumstances after the date hereof.