When taken with methotrexate, a new pill that blocks an inflammatory protein called sykkinase may be another weapon in the ongoing war against rheumatoid arthritis (RA), finds new research presented at the American College of Rheumatology Annual Scientific Meeting.

Under development by Rigel Pharmaceuticals Inc., R788 (fostamatinib disodium) is part of a new class of rheumatoid arthritis drugs that blocks syk kinase, which can trigger the inflammation that is a hallmark of RA, thereby stopping the progression of the disease. The same agent is also being studied in other diseases, including lymphoma, lupus and type I diabetes.

In the new study of 189 people with active RA who were already taking the older disease modifying anti-rheumatic drug methotrexate, those participants who also took the 100 and 150 mg doses of the new syk kinase inhibitor twice a day showed greater improvements in their rheumatoid arthritis, than did their counterparts who took a dummy pill, or placebo. The improvement was seen as early as week one.

There were also decreases in key biomarkers of RA disease activity, including interleukin-6 and matrix metalloproteinase-3 (mmp-3) levels among people who took the 100 mg and 150 mg doses of the new rheumatoid arthritis drug. There was not a significant effect in any measure seen among people randomized to the 50 mg dose.

The new drug was also safe. The major side effects were dose related and reversible. They included diarrhea and low white blood cell count.

Unlike biologic drugs that are given by injection or infusion, this new rheumatoid arthritis drug is taken by mouth, which is a huge plus, says Eric Matteson, MD, the chairman of the rheumatology department at Mayo Clinic College of Medicine, in Rochester, Minn.

“The preliminary studies are actually very encouraging in terms of clinical effect and it is kind of exciting that they are oral,” he says. If the new findings are confirmed, the new drug and others in this class may one day be used in conjunction with biologics because they act differently. “Together with biologics, syk kinase inhibitors may be even more powerful and synergistic,” he says.