Gemini Therapeutics Announces Presentation of Previously Released Data from Its Ongoing Phase 2a Study of GEM103 at Clinical Trials at the Summit

- GEM103 biological activity in intraocular compartment showed ability of potential first in class complement regulator to inhibit C3 activation and amplification

- GEM103 continues to be well tolerated and intraocular pharmacokinetics support advancing program to late-stage, adequately sized and controlled study to evaluate efficacy in geographic atrophy

- Analyses presented show imbalances in GA baseline characteristics in study eye and fellow eye that prevent efficacy assessment in uncontrolled open-label study

Gemini Therapeutics, Inc. (Nasdaq: GMTX), a clinical stage precision medicine company developing innovative treatments for genetically defined age-related macular degeneration (AMD), today announced that Chief Executive Officer, Jason Meyenburg, and Chief Medical Officer, Samuel Barone, M.D., presented in panel discussions at the Clinical Trials at the Summit on August 28, 2021. As part of the panel discussions, which included: Concept to Concrete: Turning Ideas into Action and Clinical Trials Addressing Dry AMD, management discussed some of the previously released initial data from its ongoing Phase 2a ReGAtta study of GEM103 in patients with geographic atrophy (GA) secondary to dry AMD as of May 2021.

“We were pleased to have the opportunity to present at the Clinical Trials at the Summit to further discuss our initial data released from our Phase 2a ReGAtta study of GEM103 in patients with GA secondary to dry AMD,” said Dr. Barone. “Results thus far showed that GEM103 continues to be safe and well-tolerated with no serious adverse events related to study drug and no serious ocular adverse events observed. Additionally, GEM103 also demonstrated biological activity that supports the ability of complement factor H (CFH) to regulate complement activity in patients with dry AMD and stop C3 activation and amplification in the alternative pathway. These encouraging results allow us to meet with regulators and move forward with our development plan and finalize the design of the next studies that will be powered to assess efficacy of GEM103 in the treatment of GA.”

The current ongoing Phase 2a study is open-label, uncontrolled, and was not designed to detect statistically significant treatment effect. The study design is enriched for patients with Factor H loss of function variants and permitted investigators to enroll patients with varying GA baseline characteristics. The baseline imbalances in GA characteristics in the study eye and the fellow eye do not support a reliable assessment of GA efficacy of treatment with GEM103.

Summarized observations to date regarding the previously released initial data of the ongoing Phase 2a ReGAtta study include the following:

ReGAtta study design and imbalances in GA baseline characteristics

Sixty-two patients with GA were enrolled in an open-label, single arm, uncontrolled study with 76% of patients with a CFH risk variant who received repeat doses of GEM103. The first 36 patients were enrolled in a cohort and received monthly 250μg intravitreal injections of GEM103 in a designated study eye for three months. As a result of no observed dose limiting toxicities, dosing was then increased to 500μg IVT monthly for additional three months. Additional 26 patients were enrolled in a second cohort and received three monthly doses of 500μg of GEM103 intravitreally. Total drug exposure was 28 patient years in data recently presented. This study design resulted in:

• Investigators enrolled patients with more progressed GA in the study eye in the first “250mg Cohort” and less progressed GA in the study eye in the second “500mg Cohort.” These imbalances are seen in lesion size and morphology at baseline.
• Patients in the first “250mg Cohort” were on study longer, average 6.7 months compared to 3.7 months in the second “500mg Cohort.”
• Among the 62 patients enrolled, only 45 patients (73%) had baseline GA in the fellow eye. This was not a requirement for enrollment. This, along with study eye baseline GA heterogeneity and imbalances in baseline GA size, focality and foveal involvement between study and fellow eyes do not allow the use of the fellow eye as a comparator group to assess GA efficacy.

Demonstration of biological activity, complement regulation and support for extended dosing frequency

• Both 250mg and 500mg repeat dosing resulted in immediate, durable and dose proportional reductions of intraocular complement biomarkers of C3 activation and alternative pathway amplification indicating regulation.
• Complement intraocular biomarkers continued to decrease durably with repeat dosing and will be followed as patients continue in study.
• CFH levels accumulated with GEM103 repeat intravitreal administration of 250mg and 500mg, supporting evaluation of every other month dosing in late-stage development studies.

GEM103 continued to be well-tolerated with a differentiated safety profile

• GEM103 was well-tolerated with no serious adverse events related to study drug and no serious ocular adverse events as of the recent data cut-off. There were no early discontinuations due to the study drug.
• No cases of CNV in the study eyes have been confirmed by the independent reading center’s retinal imaging analyses based on the initial data. Macular hemorrhage, suspected of neovascular AMD, was observed in the study eye of one patient at month 1 in the 500µg cohort and was determined by the investigator to be unrelated to GEM103 or the intravitreal administration procedure.
• Visual acuity remained stable (±5 EDTRS letters) throughout the study.

Information on Gemini Therapeutics, including GEM103 and initial ReGAtta data, and presentations made by the company at CTS are included in its corporate presentation which is available on Gemini Therapeutics’ website under the Investors & Media section: Events and Presentations.

Presentations of further analyses will be presented at upcoming medical conferences.

About the Phase 2a ReGAtta Study

The ongoing Phase 2a, multi-center, open-label, multiple ascending dose study of GEM103 in genetically-defined patients with GA secondary to dry AMD is designed to investigate safety and tolerability, PK, exploratory ocular biomarkers, and measures of retinal anatomy and function and not assess efficacy of GEM103 in GA. GEM103 is delivered monthly by an intravitreal injection and PK and biomarkers of complement regulation are determined from aqueous humor sampling. To date, the study has enrolled 62 patients with gene variants that have been linked to the progression of dry AMD from early to late-stage. The study’s design allowed for imbalances in GA baseline characteristics and does not inform GA efficacy and do not allow comparisons with uncontrolled fellow eye with similar imbalances.

About GEM103

Gemini’s lead program, GEM103, is a pioneering precision medicine approach, targeting trial enrichment with genetically defined patients. GEM103 targets a genetically defined subset of age-related macular degeneration (AMD) patients with complement dysregulation. Of the 15 million dry AMD patients in the United States, approximately 40% (or six million) have variants in the complement factor H (CFH) gene. Such loss of function variants are associated with increased dry AMD disease risk. GEM103 is believed to be the first ever recombinant complement regulator and is a full-length and human, recombinant complement factor H (rCFH) protein. When delivered by intravitreal injection, we believe GEM103 has the potential to address unmet medical need in genetically defined AMD patients by circumventing the complement dysfunction resulting from CFH loss of function variants and slowing the progression of their retina disease. The U.S. Food and Drug Administration (FDA) granted Fast Track Designation for GEM103 for the treatment of dry AMD in patients with CFH loss of function gene variants.

About Dry Age-Related Macular Degeneration (AMD)

Age-related macular degeneration (AMD) is a progressive retinal disease affecting millions of older adults, and the leading cause of irreversible blindness in the western world. Symptoms, which include blurry vision, loss of night vision and loss of central vision, make activities of daily living such as reading, driving and even recognizing faces progressively more difficult. Third-party reports indicate there are approximately 16 million patients with AMD in the United States alone. Dry AMD, which results from an interaction of environmental and genetic risk factors, represents about 90% of that population (or about 15 million) in the US compared to about 1.4 million with wet AMD. Genetic risk of developing dry AMD is significant, with approximately 70% attributable risk of advanced disease to heritability, while aging and smoking confer the strongest non-genetic risk. CFH risk variants occur in approximately 40% of patients with dry AMD and these patients have a significantly increased risk of developing the disease as well as progression from intermediate AMD to GA. The complement system, of which CFH is a regulator, is dysregulated in patients with these risk variants, and results in amplification of aberrant inflammatory responses in the eye. Over time, this dysregulation leads to damage to the macular region of the retina.

About Gemini Therapeutics

Gemini Therapeutics is a clinical stage precision medicine company developing novel therapeutic compounds to treat genetically defined age-related macular degeneration (AMD). Gemini’s lead candidate, GEM103, is a recombinant form of human complement factor H protein (CFH) and is designed to address both complement hyperactivity and restore retinal health in patients with AMD. GEM103 is currently in a Phase 2a trial in dry AMD patients with a CFH risk variant and a Phase 1/2a study in patients with neovascular age-related macular degeneration with or at risk for macular atrophy. Gemini has generated a rich pipeline including recombinant proteins, gene therapies, and monoclonal antibodies and is advancing a potentiating antibody for CFH, GEM307, into clinical development for treatment of systemic diseases.

For more information, visit www.geminitherapeutics.com.

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