That news comes from the drug's phase III trials, which test safety and effectiveness.
Biologic drugs, such as Actemra, target specific parts of the immune system that lead the inflammation that causes joint damage in RA. Current biologic drugs used to treat RA include Enbrel, Humira, Orencia, Remicade, and Rituxan.
Actemra is not yet available. It works on a different area of the immune system than the other biologic drugs.
One trial covered rheumatoid arthritis; the other focused on juvenile idiopathic arthritis. Results for both trials appear in the March 22 edition of The Lancet.
A related editorial voices "cautious optimism" but calls for more studies on Actemra's possible effects on cholesterol, and for head-to-head comparisons of Actemra and other biologic arthritis drugs.
Rheumatoid Arthritis Study
The rheumatoid arthritis study included 621 patients with moderate to severe rheumatoid arthritis who had already tried the drug methotrexate for their RA.
The patients got injections of a higher dose of Actemra, a lower dose of Actemra, or a placebo every four weeks for six months.
At the end of the study, 59% of the patients who got the higher Actemra dose, 48% of those taking the lower Actemra dose, and 26% of those who got the placebo had at least a 20% improvement in their signs and symptoms of RA, which is considered significant improvement.
Upper respiratory tract infections were the most common side effects seen in the Actemra group. Liver enzyme levels also rose for some Actemra patients, but those were typically one-time events and weren't linked to symptoms of liver disease, according to the researchers.
Total cholesterol and LDL ("bad") cholesterol levels rose in the Actemra users. The reason for that isn't clear. Major heart "events" -- such as heart attacks -- weren't more common with Actemra use, but the study only lasted for six months, which may not have been long enough to detect cardiovascular risk.
WebMD reported on the study last June, when researcher Josef Smolen, MD, of Austria's Medical University of Vienna, presented the findings in Barcelona, Spain, at the European League Against Rheumatism's annual meeting.
The study, which didn't look at the drug's long-term safety, was funded by Hoffmann-La Roche and Japan's Chugai Pharmaceutical Co., which are developing Actemra.
Juvenile Idiopathic Arthritis Study
The juvenile idiopathic arthritis trial included 56 children in Japan who had tried other drugs to treat their arthritis.
First, all of the children got three doses of Actemra every two weeks for six weeks. Then 43 kids whose arthritis had improved with Actemra treatment kept getting Actemra; all in all, they took Actemra for four months.
Actemra trumped the placebo and "might be a suitable treatment in the control of this disorder, which has so far been difficult to manage," write Yokohama City University's Shumpei Yokota, MD, and colleagues.
Adverse events were typical of other biologic drugs and included upper respiratory-tract infections and stomach flu. Anaphylactic allergic reactions and increases in liver enzyme levels were rarer.
The study was funded by Chugai Pharmaceutical Co.
Expert: Head-to-Head Trials Needed
Editorialist Tim Bongartz, MD, who works at the Mayo Clinic College of Medicine in Rochester, Minn., writes that he is "excited about the ongoing expansion of therapeutic options for rheumatoid arthritis and, especially, systemic [juvenile idiopathic arthritis]."
But he cautions that the evidence doesn't show how Actemra's risks and benefits stack up against other treatment choices.
"In an ideal world, comparative trials of new drugs with other effective treatments, powered to detect important safety and efficacy endpoints, would provide this information, which I regard as essential," writes Bongartz.
"It is not clear that these trials will be available before the likely approval of tocolizumab [Actemra], and it may be up to investigators to initiate the head-to-head comparisons needed to address these issues," adds Bongartz.