Recruitment to a Phase II/III trial has been initiated in the US to test the potential of an inhibitor of complement C5 (Zimura) to treat patients with geographic atrophy. The study will randomise approximately 300 patients into 1:1:1 allocations to test two different doses of an aptamer compared to a control. Participants will receive monthly intravitreal injections for a period of 24 months, following which the primary outcome of mean change in best corrected visual acuity (Early Treatment Diabetic Retinopathy Study [ETDRS] letters) from baseline to month 24 will be assessed. Patients >50 years will be recruited from 9 US centres.
Previously, a multi-center, dose-escalating study of the drug, administered in combination with an anti-VEGF agent showed that the treatment was generally well tolerated. A subgroup of 43 patients who had not previously been treated with anti-VEGF therapy were administered with six injections of the aptamer and anti-VEGF treatment, following which a mean increase in VA from baseline at all time points was recorded by the study team. Results from administration of the various doses showed an improvement in mean VA from baseline of 13.6 letters for patients receiving the 0.3 mg dose, an improvement of 11.7 letters for patients treated with the 1.0 mg dose and an improvement of 15.3 letters for patients receiving 2.0 mg.
The anti-C5 aptamer, owned and sponsored by New York-based Ophthotech, is designed to inhibit complement C5-mediated inflammation. Aptamers, in development since the early 1990s, are single-stranded oligonucleotides with specific three-dimensional shapes allowing for selection against a broad range of molecular targets. The aptamer used to target the complement pathway was designed to interfere with the complement cascade that leads to drusen formation, a key risk factor for AMD and a potential precursor of wet AMD. Commenting on the clinical milestone, David R. Guyer, MD, Chief Executive Officer and Chairman of the of Ophthotech stated, “We plan to explore the potential of Zimura as a treatment for geographic atrophy. In addition, the emerging strength of science from published independent genetic variation studies relating to the role of complement inhibition in wet AMD along with our earlier Zimura study results in wet AMD are encouraging. We are therefore pleased to have recently announced the initiation of a wet AMD treatment burden reduction study of Zimura combination therapy. These are important milestones for Ophthotech as our effort to develop therapies to treat underserved populations in all forms of AMD continues to advance.”