Both medications are in a class called biologics, which are designed to inhibit parts of the immune system that cause inflammation, a central feature of rheumatoid arthritis. The two drugs, though, work in slightly different ways.
Actemra works by inhibiting the chemical signal interleukin-6 (IL-6). Humira blocks tumor necrosis factor-alpha (TNF-a). Most people who take either drug do so in combination with other disease-modifying medications, like methotrexate.
But about a third of people who take the drugs can't take methotrexate, says Jeffrey Curtis, MD, MPH, a rheumatologist and assistant professor of medicine at the University of Alabama at Birmingham, where he also directs the Arthritis Clinical Intervention Program.
"That's the importance of this study. If you have somebody who can't or won't tolerate methotrexate or other DMARDs [disease-modifying antirheumatic drugs], which biologic should we pick?" Curtis was the lead investigator for the study in the U.S. He has also been a paid consultant for Roche, the maker of Actemra, and other companies that make arthritis drugs. The study was funded by Roche.
In a head-to-head comparison study that included 325 people with rheumatoid arthritis (RA), nearly 40% of those taking Actemra went into remission, compared to just over 10% of the Humira group. In addition, over half on Actemra had low disease activity, while fewer than 20% of those on Humira saw this degree of improvement.
Disease activity takes into account the number of swollen and tender joints a person with RA has as well as levels of body-wide inflammation, which are measured by blood tests.
Curtis points out that while those numbers look pretty dramatic, by other measures, which mostly gauge a patient's symptoms and how they're functioning, the differences were less clear-cut.
"If you say to patients, you can choose one drug or the other and the patient says, 'Well how much better am I going to get?' You could say, 'You know, you may have a couple fewer tender or swollen joints.'"