Posted: Nov 8, 2010 9:20 PM
Nov. 8, 2010 (Atlanta) -- An experimental pill may help to reduce pain and swelling and improve physical function in people with rheumatoid arthritis, according to findings from a late-stage study of more than 600 patients.
There was also a signal that people given the new drug, tasocitinib, may be more likely to go into remission than people given placebo. However, that finding could have been due to chance, says study leader Roy Fleischmann, MD, of the University of Texas Southwestern Medical Center in Dallas.
The findings were presented at a news briefing here, held in advance of the Fleischmann's formal presentation at the American College of Rheumatology meeting.
The hope is that the new pill will offer patients an attractive alternative to the injectable agents that dominate the RA market, says Alan K. Matsumoto, MD, of Arthritis and Rheumatism Associates in Washington, D.C. He was not involved with the work.
The injectables -- which include Enbrel, Humira, and Remicade -- can cost as much as $1,500 a month and carry a risk of infection, he says.
"The fact that tasocitinib is given orally is extremely exciting," Matsumoto tells WebMD. "If approved, it will become the first new oral drug for rheumatoid arthritis since Arava was OK'd in the late 1990s," he says.
Tasocitinib belongs to a new class of oral drugs, known as JAK inhibitors, that inhibit immune system cells that are thought to cause inflammation.
In rheumatoid arthritis, the immune system is inappropriately turned on, causing inflammation, predominantly in the joints. This, in turn, can cause pain and lead to permanent joint damage.
In the study, 611 people with moderate to severe rheumatoid arthritis who had an inadequate response to at least one other drug were randomly assigned to one of two doses of tasocitinib or placebo.
Among the findings:
But for the third primary study goal, remission according to the Disease Activity Score-28 (DAS-28) at three months, tasocitinib did not offer a substantial advantage at either dosage relative to placebo.
DAS-28 scores take into account such measures as the number of joints tender to the touch and the number of swollen joints. Using this measure, 10% of patients on the higher tasocitinib dosage, 6% on the lower dose, and 4% on placebo were in remission at three months. But the difference in remission rates did not reach what doctors call statistical significance, Fleischmann tells WebMD. He says he received consulting fees and research support from Pfizer, which makes the drug and funded the new study.
After three months, all patients in the placebo group were switched over to one of the two doses of tasocitinib for another three months; the patients who had been on tasocitinib stayed on their original doses.
Over the entire six-month period, 25 patients (4%) taking the new drug had serious adverse events, with six cases of serious infection.
On the positive side, "we have not seen the tuberculosis, or the opportunistic infections, that we've seen with [other drugs for RA]," Fleischmann says.
People taking tasocitinib were also more likely to experience drops in white blood cell count and increases in bad LDL cholesterol levels.
In findings that muddied the water, however, there was also an increase in good HDL cholesterol levels in some patients on tasocitinib.
"As a clinician, I'm not sure what this means," Fleischmann says.
Inflammation can depress blood lipid levels, and anti-inflammatory treatments can cause them to rise, he says.
Whether the LDL changes are actually harmful to patients is unclear, says Fleischmann, noting that tasocitinib was not associated with a rise in heart attack or stroke rates.
Says Matsumoto, "As with all drugs, we need long-term information on safety. But from both and effectiveness and safety view, tasocitinib looks to be very promising."
Tasocitinib is also being studied for the treatment of several other disorders, including psoriasis, Crohn's disease, and ulcerative colitis. No price has been set.
This study was presented at a medical conference. The findings should be considered preliminary as they have not yet undergone the "peer review" process, in which outside experts scrutinize the data prior to publication in a medical journal.