Quark Development Partner Pfizer Presents PF-04523655 In Vivo Activity At ARVO

PF-04523655 is a chemically-modified siRNA drug candidate being co-developed by Quark and Pfizer for the treatment of wet age-related macular degeneration (wet-AMD) and diabetic macular edema (DME).

According to Pfizer researchers, PF-04523655 was designed to be resistant to nuclease degradation that can occur during normal cellular uptake processes in the eye without using a specific delivery vehicle.

Results were presented in an abstract titled ‘Dose-Related Gene Silencing of RTP801 with the siRNA PF-04523655 in Long Evans Rat Models of STZ Induced Diabetes and Laser Induced CNV.’ The study, led by Kay Rittenhouse, head of the Translational Medicine Ophthalmology, specialty care business unit at Pfizer, demonstrated reduction of RTP801 mRNA levels in rat retina following intravitreal administration.

Daniel Zurr, president and chief executive officer of Quark Pharmaceuticals, said: “These results on in vivo activity of PF-04523655 represent an important step forward for the field of synthetic siRNA therapeutics. Importantly, the data presented by Pfizer demonstrate that siRNAs chemically modified to improve stability are taken up by cells and elicit RNAi activity in vivo without requiring complex delivery formulations.”

James Thompson, vice president of pharmaceutical development at Quark Pharmaceuticals, said: “High concentrations of synthetic siRNA can be attained in the eye following intravitreal administration, making ocular diseases a particularly relevant therapeutic area for siRNA therapeutic development.

“A rise in the aging population and incidence of diabetes are contributing to the increase in wet-AMD and DME, yet many of these patients suffer from inadequate treatment from currently available therapies. Use of synthetic siRNAs represents a novel therapeutic approach to potentially address these diseases.”