The drug, from a company called Rigel, is R788 or fostamatinib disodium. The oral drug targets an enzyme called Syk. Nobody is exactly sure of the role Syk plays in rheumatoid arthritis. But there's an overabundance of Syk in the fluid of arthritic joints, and the enzyme is part of the runaway immune machinery that increases joint inflammation.
There's at least one theoretical concern about R788. Normally, the Syk enzyme helps suppress tumors. Women with breast tumors have low levels of Syk.
It's not clear whether long-term use of R788 will increase cancer risk; longer-term clinical trials will have to evaluate this risk.
For now, R788 looks very promising, the researchers report.
"Inhibition of the Syk pathway offers a new drug target for rheumatoid arthritis," Weinblatt and colleagues conclude.
The Weinblatt study and an editorial by NIH researchers Juan Rivera, PhD, and Robert A. Colbert, MD, PhD, appear in the Sept. 30 issue of the New England Journal of Medicine. Rigel funded the study, and three of the study's six authors are Rigel employees. Weinblatt reports receiving grants, fees, or honoraria from a number of drug and biomedical companies, including Rigel.