Rigel Pharmaceuticals Inc announced the completion of its Phase I/II clinical study of R112, an experimental drug to treat allergic rhinitis, the chronic nasal congestion that afflicts approximately 20 to 25 percent of the U.S. population. The Phase I/II study evaluated the efficacy and safety of a single intranasal administration of R112 in volunteer patients with asymptomatic seasonal allergic rhinitis. Based on preliminary results, R112 in this study demonstrated significant improvement or consistent positive trends in reducing the release of chemical mediators involved in mast cell activation, one of the earliest steps in the initiation of an inflammatory response in allergy and asthma. Additionally, even though this particular study involved only a single dose of R112, improvements in symptom scores were noted, although not reaching statistical significance given the size of the study. No clinically significant adverse effects were attributed to R112 during this trial or in the prior Phase I clinical trial.

"We are extremely pleased with these preliminary study findings, which position inhibition of IgE signaling in mast cells with a small molecule drug as a promising approach for treating allergic rhinitis and possibly other respiratory-related allergic diseases such as asthma," said Harold Nelson, of National Jewish Medical and Research Center, the study's Principal Investigator.

"Unlike current allergy drugs, such as antihistamines or antileukotrienes, that target only a single chemical mediator involved in mast cell activation, R112 may offer a new, comprehensive treatment strategy by potentially blocking all major chemical mediators of inflammation involved in mast cell responses, "said Donald Payan, Rigel's CSO and Executive Vice President.