AZ/Rigel RA drug hits PhIIb paydirt

AstraZeneca's $100 million upfront wager on Rigel's experimental rheumatoid arthritis therapy R788 has paid off with a promising set of mid-stage data just as the partners prepare for their Phase III hurdle. Researchers reported that two doses of fostamatinib proved significantly better than a placebo in reducing symptoms of the disease.

AZ handed over the $100 million to Rigel earlier this year while promising more than $1.2 billion in regulatory and sales milestones to seal the pact. And the data for the oral syk inhibitor, a new class of RA drugs, helped illuminate what the pharma company found so compelling.

In the Phase IIb study of fostamatinib, researchers found that 67 percent of the methotrexate-resistant patients taking 100 mg of the experimental therapy twice daily achieved at least a 20 percent improvement in a range of symptoms such as swollen joints, pain and physical function. Impressively, more than a third of the group hit that mark in less than a week. Somewhat more than half of the patients--57 percent--taking a once-daily dose of 150 mg hit the same ACR 20 mark, compared with 35 percent of the placebo arm.

"In this study, we saw a significant clinical benefit in this rheumatoid arthritis population and a manageable safety profile," says Stanford's Mark Genovese. "Based on the data, further study of fostamatinib as an oral agent for the treatment of patients with rheumatoid arthritis is certainly warranted." The Phase III program, which will be run by AstraZeneca, is expected to start before the end of this year.

- here's the AZ press release for more info