AstraZeneca Plc’s experimental drug fostamatinib showed mixed results in treating rheumatoid arthritis in a late-stage clinical trial. The shares of partner Rigel Pharmaceuticals Inc. plunged.
The treatment showed a statistically significant improvement in a measure of arthritis symptoms in the study known as Oskira-1, the London-based company said in a statement today. Fostamatinib didn’t show improvement in an x-ray that tracks the progression of joint damage, the company said.
The trial shows the drug “has an effect on the signs and symptoms of rheumatoid arthritis,” Briggs Morrison, executive vice president of global medicines development, said in the statement. “We will await the results of the remaining Phase III studies, Oskira-2 and Oskira-3, to further evaluate and characterize the profile of fostamatinib as a potential treatment for rheumatoid arthritis.”
The results may add to concern that fostamatinib lacks commercial potential. The drug failed to show a benefit versus Abbott Laboratories’ Humira in a mid-stage trial, AstraZeneca said in December. The company, the U.K.’s second-biggest drugmaker, needs new products to ease a sales slump caused by competition from generic medicines.
Results from Oskira-2 and Oskira-3 are due later in the second quarter, AstraZeneca said.
AstraZeneca fell as much as 0.4 percent to 3,290.5 pence and was trading up 0.1 percent at 12:52 p.m. in London. The stock has returned 25 percent in the past year, including reinvested dividends, compared with a 30 percent for the Bloomberg Europe Pharmaceutical Index.
Rigel, based in South San Francisco, California, sank 25 percent to $5.68 at 7:52 a.m. New York time. The shares had lost 5.9 percent in the last year through yesterday.
Fostamatinib is AstraZeneca’s only experimental product that could make a meaningful difference to earnings this decade, an analyst at Nordea wrote in December.