Rigel Pharmaceuticals, Inc. announced the presentation of clinical data for R112, the company's lead candidate for the treatment of allergic rhinitis, during a poster session at the annual meeting of the American Academy of Allergy, Asthma and Immunology (AAAAI) in San Francisco, CA. The phase I/II single dose trial demonstrated that R112 was well tolerated and showed favorable biological effects.

The presentation entitled, "The Effect of a Novel Inhibitor of Mast Cell Activation on Mediators, Symptoms and Nasal Patency in Allergic Rhinitis," reports data from the Phase I/II study, evaluating R112 for the treatment of allergic rhinitis. The study evaluated 20 patients in a randomized double blind crossover trial. One dose of R112 or vehicle control was given intranasally followed by nasal allergen challenge 15 minutes later. Chemical mediators and symptoms were then measured. Brenda Guyer, MD, will present the study results.

The data demonstrated that subjects treated with R112 were indistinguishable from the vehicle controls across a wide range of clinical and laboratory safety tests. In addition to the positive safety data, the study demonstrated a statistically significant decrease in prostaglandin D2 (PGD2), a key immune mediator that was highly correlated with improvements in the allergic symptom of rhinorrhea. The study also showed other favorable responses.

"We are encouraged that the data demonstrates that R112 is well tolerated and has a positive safety profile," said Donald Payan, MD, Rigel's chief scientific officer and executive vice president. "With these positive results and the promising decrease in PGD2, and other favorable changes, Rigel looks forward to further investigating R112 as a potential novel allergy therapeutic."

Based on the success of this phase I/II trial, Rigel plans to initiate phase II efficacy trials in Q2, 2004. The randomized, placebo-controlled park study will provide broader indications of R112's potential clinical value. The study will take place in two locations in different parts of the country, where patients will spend two days in an outdoor setting during the high-pollen season. Phase II results are expected in the second half of 2004.