Gemini Therapeutics, Inc. announced initial data from its Phase 2a ReGAtta study of GEM103 as of May 2021 in patients with geographic atrophy secondary to dry AMD. ReGAtta is a dose escalation trial of GEM103, which is intravitreally administered recombinant human complement factor H (CFH), in dry AMD patients. The trial, which remains ongoing, is designed to evaluate safety and tolerability, as well as measures of intraocular pharmacokinetics (PK) and disease-relevant biomarkers, to inform the late-stage development program. ReGAtta was designed to evaluate repeat dosing of GEM103 and assess its safety in an open-label study that enrolled 62 patients with GA secondary to dry AMD. The first 36 patients enrolled received monthly 250µg intravitreally administered doses of GEM103. After evaluating the safety profile of repeated dosing over three months, patients were dose escalated to 500µg and an additional 26 patients enrolled and received monthly 500µg doses. After completing the first six months of dosing, each patient will have the option to continue receiving GEM103 for up to an additional 12 months. Patients enrolled in ReGAtta had a mean age of 78 and GA secondary to dry AMD in the study eye with 63% of patients also having GA in the fellow eye. Choroidal neovascularization in the study eye was an exclusion criterion, however 30% of patients had a history of CNV in the fellow eye at baseline. Among the baseline characteristics in the study eye, mean best corrected visual acuity (BCVA) score, as measured by Early Treatment Diabetic Retinopathy Study (ETDRS) letters, at enrollment was 61.5 (with a range of 14-86). Average GA size was 8.1 mm2. The GA was foveal in 68% of patients and multifocal in 63% of patients. Loss of function variants in the CFH gene were confirmed in 55 of the 62 patients enrolled. A total of 43 patients carry a homozygous AMD risk variation at the 402 locus of the CFH gene and six patients carry a rare heterozygous variant in CFH. Summarized results observed to date in the ongoing Phase 2a ReGAtta study include the following: Demonstration of Biological Activity, Complement Regulation and Dosing Frequency Intraocular measures of CFH and biomarkers demonstrated GEM103’s biological activity to regulate complement and support every other month dosing. Both 250µg and 500µg doses of GEM103 resulted in sustained, elevated CFH levels from the first evaluated time point of one month (at least 6-fold and 12-fold above baseline, respectively) that continued to increase dose dependently; Changes in biomarkers of complement activation indicated that GEM103 has the ability to regulate the complement system and overall disease-related inflammation, with an ~40% reduction in Ba, ~20% reduction in C3a and an increase in CFB, consistent across all genotypes. 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 May. There were no early discontinuations due to the study drug; Over 390 injections of GEM103 were administered, which equates to a total of 28 patient-years of exposure. Treatment was well-tolerated with only 16 patients (26%) experiencing adverse events in the study eye. Among these events, 12 patients’ adverse events were related to the intravitreal administration procedure with conjunctival hemorrhage as the most common reported adverse event; Active monitoring was conducted for retina-specific safety including inflammation and CNV. Dilated retina exams were conducted at every study visit and retinal imaging was performed every three months. An independent reading center reviewed such data; There were no endophthalmitis and no vitritis, retinal vasculitis or vascular occlusive events. Mild iritis (< 1+ cell) was observed in the study eye in three patients (4.8%); all cases resolved with either observation only or topical therapy. One case was reported as related to GEM103, and all patients continued on study without disruption of GEM103 dosing schedule; One case of CNV in a study eye presented as a macular hemorrhage at month 1 in the 500µg cohort was determined by the investigator not to be related to GEM103 or the intravitreal administration procedure. The patient is receiving anti-VEGF treatment and has continued on study; There were no cases of CNV confirmed in the study eye by the independent reading center’s analysis of the retinal imaging. Visual acuity remained stable (±5 EDTRS letters) throughout the study; GA progression at three months and six months in the study eye compared to fellow eyes that also meet the inclusion criteria was statistically indistinguishable.