Calif.-based Quark Pharmaceuticals, engaged in the discovery and development of RNAi-based therapeutics, has received results from a prospective randomized phase II trial, the DEGAS study. This study evaluated the safety and efficacy of PF-04523655 (RTP801I-14) in patients with diabetic macular edema (DME). There were 184 patients randomly assigned to four treatment groups; three dose levels of PF-04523655 (RTP801I-14) (0.4mg, 1mg, and 3mg) or laser. The study was designed with a primary endpoint of mean visual acuity improvements over baseline at 24 months.
Interim results at 12 months showed there were no drug-related serious adverse events (SAEs). Following 12 months of treatment with PF-04523655 (RTP801I-14), a dose-dependent improvement in visual acuity was observed with the best results achieved at the 3mg dose level. At this dose, the mean improvement from baseline on a visual acuity test was 5.8 letters for all patients enrolled in this dose group while in patients treated with laser photocoagulation control (the current standard of care) visual acuity improved by only 2.4 letters on average (p=0.08). Furthermore, in a separate secondary analysis of the 111 patients who completed the 12-month follow-up visit, the mean improvement from baseline on a visual acuity test in the 3mg group was 9.1 letters while in patients treated with laser photocoagulation control visual acuity improved by only 3.2 letters on average (p
Based on these results, and in view of a dose-related effect on vision, Quark and Pfizer have mutually agreed that a phase IIb study will be conducted by Quark at its own expense under a protocol mutually agreed upon by Quark and Pfizer.