Washington Editor

Rigel Pharmaceuticals Inc.'s stock soared 37.7 percent Monday after the company released favorable news from a Phase II study evaluating the use of R112 in allergic rhinitis.

The company's shares (NASDAQ:RIGL) finished Monday at $18.79, up $5.14.

Day 1 data from the 316-patient trial showed that R112 reduced the Global Nasal Allergy Symptom Score by 7 points (38 percent) vs. 5.4 points (29 percent) for placebo (p=0.0005), an absolute difference of 9 percent, and a relative improvement over placebo of 24 percent. Results on Day 2 were of similar magnitude (p=0.0016), the company said.

R112 appeared to dramatically impact allergic rhinitis, Raul Rodriguez, chief operating officer of South San Francisco-based Rigel, told BioWorld Today. "The fast onset of R112 is a tremendous advantage," he said, adding that it started working in 30 minutes and had an eight-hour lasting effect.

The data also suggested that R112 works on single individual symptoms, including stuffy nose, itchy nose, runny nose, sneezing, cough, headache, facial pressure and the number of times patients had to clear their throats, Rodriguez said.

R112, discovered at Rigel, binds to an intracellular target (syk, a kinase that regulates IgE receptor signaling) in mast cells and interrupts the signal from the IgE receptor, thus preventing cellular activation and subsequent chemical mediator release. But unlike common allergy drugs, such as antihistamines or anti-leukotrienes that block only a single mediator, R112 is designed to block all of the major pathways that are triggered in an allergic attack, potentially making it a more effective and comprehensive drug, the company said.

Since large Phase III trials are anticipated, Rigel expects to partner R112 by the end of the year. Indeed, for indications such as allergic rhinitis, Don Payan, Rigel's chief scientific officer, said the company might need data on 3,000 people to satisfy regulatory requirements.

"The business model for the company is to take a product through Phase II, prove it works definitively and then find a big pharma company that is better positioned to finish large trials and market the product," he said. "We've been in discussions with several big pharma players that have a presence in allergy and asthma."

The Phase II study (also referred to as Park) was a randomized, placebo-controlled trial designed to measure the safety and effectiveness of R112 as an intranasal treatment. There were no significant drug-related adverse events reported in the trial, and side effect frequencies were indistinguishable from placebo. Nevertheless, Payan expects the FDA to require more safety data, since R112 would be used broadly.

Allergic rhinitis affects nearly 59 million people, or 20 percent of the U.S. population, the company said, adding that the overall market is about $4 billion.

Beyond R112, Rigel is developing R803, an antiviral in a Phase I/II study for hepatitis C, and R406, a rheumatoid arthritis candidate expected to enter humans later this year.

Rigel also is studying an unnamed asthma candidate that should enter the clinic next year.