Cancer drug Rituxan combats arthritis, study shows
Friday October 25, 6:32 pm ET
By Deena Beasley
LOS ANGELES, Oct 25 (Reuters) - A drug now used to treat non-Hodgkin's lymphoma, a cancer of the immune system, is also effective against rheumatoid arthritis, according to researchers.
Rheumatoid arthritis is an inflammatory disease estimated to afflict up to 2.6 million Americans. The disease, which can be severe and potentially disabling, causes pain, swelling, stiffness and loss of function in the joints. It often involvesthe joints in the shoulders, knees, hands or feet.
"This opens up a completely new avenue for treating rheumatoid arthritis -- one with the potential for putting the disease in long-term remission," said Dr. Jonathan Edwards of the University College, London Centre for Rheumatology and lead investigator of the study being presented on Saturday at a meeting of the American College of Rheumatology.
The drug, called Rituxan, is a bioengineered antibody that works by binding to a protein found only on the surface of normal and malignant B cells -- infection-fighting white blood cells. From there, it recruits the body's natural defenses to attack and kill the marked cells without affecting the regeneration of healthy B cells, researchers said.
Research has shown that B-cells are abundant in inflamed arthritic tissue and joints, leading the drug's developers Genentech Inc. (NYSE:DNA - News) and Idec Pharmaceuticals Inc. (NasdaqNM:IDPH - News) to suspect that Rituxan could play a role in combating the inflammatory disease.
"This study brings up a lot of questions about the mechanisms of the disease," said Dr. Hal Barron, vice president of medical affairs at Genentech.
DUAL THERAPY CUTS SYMPTOMS
Mid-stage results from 122 patients in a 24-week trial show that 80 percent of 30 patients taking the anti-inflammatory drug methotrexate who were also treated with Rituxan saw at least a 20 percent improvement in symptoms. Fifty percent of those patients showed a 50 percent improvement and 23 percent had a 70 percent improvement.
Methotrexate alone cut symptoms by at least 50 percent in 32 percent of the 31 patients in that arm of the study.
"You can't start with patients who've never had methotrexate, so the study design was a compromise," Edwards said. "The results suggest that if you put a patient on the combination from baseline you would do about 15 percent better."
The researcher said Rituxan works at least as well as another new class of biotechnology drugs, known as TNF-inhibitors, used to treat rheumatoid arthritis.
"The added advantage of Rituxan is that it is given in two IV (intravenous) infusions two weeks apart and that can set the patient up for 15 months or more," Edwards said.
TNF-inhibitors work by blocking a protein that causes inflammation. The drugs include Amgen Inc.'s (NasdaqNM:AMGN - News) Enbrel, given by injection twice a week, and Johnson & Johnson's (NYSE:JNJ - News) Remicade, given intravenously every two months.
Edwards, who said one of his patients given Rituxan has been in remission for three years, said treating arthritis by attacking B cells could induce months-long symptom relief that might be prolonged with adjunctive therapies.
Also, because TNF-inhibitors suppress the immune system's T-cells, raising the risk of serious infections like tuberculosis, Rituxan may be safer, he said.
"We know enough about Rituxan to see that it is not as immunosuppressive as anti-TNF drugs," the researcher said.
ONE DEATH IN TRIAL
There are, however, questions about whether Rituxan raises the risk of chest infections in arthritis patients. He said one Rituxan patient in the trial died, although the death was found to be unrelated to the medication.
"If you take away people's B cells, they are going to be less able to fight infection," he noted, adding that ideally there may be a way to one day refine the treatment so that it knocks out only those B cells specific to arthritis.
Edwards also said that by his calculations, treatment with Rituxan would cost $6,000 to $7,000 a year, compared with about $15,000 a year for the anti-TNF drugs.
Final results for all 161 patients in the Phase 2 arthritis trial will be announced at a later date, Barron said.
"We have shown significant biologic activity. We have to treat more patients and gather more data," he added.
Genentech, Idec and Roche Holdings AG (ROCZg.VX) have said they will consider launching a pivotal-stage trial of Rituxan in rheumatoid arthritis next year. |
