Last week, I discussed one of the newer biologic agents on the market for patients suffering from rheumatoid arthritis, Rituxan. Today, I will focus on the other biologic agent which also has become available in the last few months, Orencia (abatacept). Like Rituxan, it is an intravenous medication indicated for patients who have not responded adequately to Humira, Remicade or Enbrel. Unlike Rituxan (which targets the inflammatory damage resulting from B cells), Orencia attacks the activation of T-cells, which play a large role in causing the inflammation seen in rheumatoid arthritis. Interestingly, the tissue lining the joints of rheumatoid arthritis patients is invaded by inflammatory cells dominated by T-cells, so it comes as no surprise that researchers have been greatly interested in inhibiting T-cell activation.
Specifically, Orencia inhibits one of the signals required for the full activation of T-cells, thereby reducing the ability of T-cells to participate in the inflammatory process which causes joint pain and swelling in the rheumatoid arthritis patient.
Orencia was well tolerated and effective in a study of patients not responding to methotrexate for their rheumatoid arthritis. In this study, patients were given either placebo (a “fake” intravenous infusion) or Orencia. After six months, the patients on the combination of Orencia and methotrexate had a significantly better improvement in their rheumatoid arthritis compared to those patients taking the placebo and methotrexate. And in fact, the number of patients improving increased over a full year of observation. There was a low incidence of serious infections or infusion reactions.
Another study considered those rheumatoid arthritis patients who were failing drugs such as Enbrel, Humira and Remicade.. This study also showed after six months a significant improvement in patients on Orencia compared to placebo. Likewise, the incidence of adverse reactions was low, as was the need to stop the Orencia due to an adverse event.
In conclusion, while Orencia is certainly not a cure for rheumatoid arthritis, it is important for the patient to know that there are drugs available now which may give great relief where other treatments have failed. As researchers continue to develop agents which target the many mechanisms responsible for the inflammatory response which causes rheumatoid arthritis, there will be more patients who benefit from the tailored treatment approach which a wider variety of treatments will allow.
There will be those patients whose disease is perhaps more “B cell driven,” and who might therefore respond more impressively to Rituxan. Or those patients whose inflammatory activity will be halted by the T-cell-fighting effects of Orencia, but not the tumor necrosis factor inhibition of Enbrel. And there will be those patients who do just fine with low dose methotrexate. Much research still needs to be done to allow the physician to be able to predict who will respond to what. For now, we all must be satisfied with trying different medications or combinations of medications until the “right” treatment is found for an individual patient.
Published On: June 28, 2006