But the real test for tocilizumab lies in head-to-head drug trials, expert says
THURSDAY, March 20 (HealthDay News) -- The new anti-arthritis drug tocilizumab, now being tested, appears to be effective in relieving the symptoms of rheumatoid arthritis in both adults and children, according to the results of two new studies.
Tocilizumab works by blocking the interleukin-6 receptor. Interleukin-6 is a molecule involved in promoting the painful inflammation in rheumatoid arthritis.
The new findings are published in the March 22 issue of The Lancet.
However, one expert isn't convinced, especially for adults, that comparing tocilizumab to a placebo -- as was done in these studies -- proves that the drug is a better option than existing medications.
"It's not good enough to know if the new medication is working better than nothing," said Dr. Tim Bongartz, a rheumatologist at the Mayo Clinic College of Medicine and author of an accompanying editorial in the journal. "To answer the question of which of four or five [drug] options available I should choose, we need to know all the potential benefits and potential risks," he said.
In one study, led by Dr. Josef Smolen, of the division of rheumatology at the Medical University of Vienna, Austria, 623 people with moderate to severe rheumatoid arthritis were randomly assigned to receive tocilizumab or a placebo. In addition, the patients continued to receive the standard arthritis drug methotrexate.
The researchers found that after 24 weeks, 59 percent of the patients taking the highest dose of tocilizumab had at least a 20 percent improvement in symptoms of rheumatoid arthritis, compared with 26 percent of the patients receiving a placebo.
The most common serious side effects were severe infections among six patients receiving the highest dose of tocilizumab, according to the report.
The study was funded by drug makers F. Hoffman-La Roche and Chugai Pharmaceuticals, which together are developing tocilizumab.
"These data provide evidence that inhibition of interleukin-6-mediated pro-inflammatory effects significantly and rapidly improves the signs and symptoms of rheumatoid arthritis," Smolen's team wrote. "Thus, tocilizumab could be an effective agent for the treatment of patients with moderate to severe rheumatoid arthritis."
But Bongatrz countered that "it's no surprise that tocilizumab works better than nothing [placebo]. The question is, does it work better than the alternatives we already have available?"
In addition, there are potential problems with tocilizumab, Bongartz said. For one, this study didn't show whether the drug slows the progression of the disease. Also, the drug significantly increased patients' cholesterol levels, which Bongartz finds troubling.
In the second report, Japanese researchers, led by Dr. Shumpei Yokota, of the department of pediatrics at Yokohama City University School of Medicine, started 56 children, ages 2 to 19, on tocilizumab. These children all had systemic-onset juvenile idiopathic arthritis, which did not respond to the usual arthritis treatment. This is a common problem with this type of arthritis, the researchers noted.
After six weeks, children who had achieved a 30 percent reduction in their arthritis symptoms were randomly assigned to continue to receive tocilizumab or a placebo.
Of the 43 children in that phase of the study, 16 out of 20 who received tocilizumab continued the improvement they had made in the first phase of the trial, compared with only four of 23 children receiving a placebo, the researchers found.
During an additional 48 weeks in which 48 children continued to receive tocilizumab, 47 children achieved a 30 percent reduction in their symptoms, 45 children achieved a 50 percent reduction in their symptoms, and 43 children ultimately achieved a 70 percent reduction in their symptoms, according to the report.
Side effects included gastrointestinal bleeding, bronchitis, and gastroenteritis.
"The results of this placebo-controlled and open-label extension study with tocilizumab in children with systemic-onset juvenile idiopathic arthritis show a sustained clinical improvement and a favorable risk-benefit profile," the Japanese team wrote. "The findings of this study might represent a step forward in the control of a disease that has previously proved to be difficult to manage."
The study was funded by Chugai Pharmaceuticals.
Bongartz said tocilizumab may be worth a try with pediatric patients.
"The treatment options are pretty sparse, and children usually don't respond very well to methotrexate or other drugs, so here I think it's easier to decide in favor of initiating tocilizumab therapy," Bongartz said. "My threshold for initiating tocilizumab therapy would be lower, because I can't offer these children a lot of other choices."
New treatment options against rheumatoid arthritis are always welcome, Bongartz said. Still, he is cautious about using tocilizumab.
"It's another opportunity to offer treatment to patients who don't respond to first-, second- or third-line therapy, but I don't know if it works better than other established therapies. Based on the data available, it's almost impossible to make an informed decision about its benefits or potential harm," Bongartz said.
For more on arthritis, visit the Arthritis Association.
SOURCES: Tim Bongartz, M.D., department of internal medicine, division of rheumatology, Mayo Clinic College of Medicine, Rochester, Minn.; March 22, 2008, The Lancet
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