Rilonacept works by blocking the pro-inflammatory protein known as interleukin-1 (IL-1). It’s currently approved to treat CAPS, or cryopyrin-associated periodic syndromes, a group of rare, inflammatory diseases, but some doctors already use it “off label” to treat sJIA.

Two other biologics currently approved to treat sJIA, anakinra (Kineret) and canakinumab (Ilaris), also target IL-1, but in different ways. A third biologic, tocilizumab (Actemra), targets interleukin-6.

“We don’t know which is the better strategy,” says Dr. Ilowite. Currently, he says, ACR treatment guideline favors IL-1 inhibition. “Our data will likely impact these recommendations in the future,” he says.

If rilonacept is approved by the FDA for treating sJIA, it would offer some distinct advantages over the other IL-1 inhibitors, says Dr. Ilowite.

“Anakinra is given by daily, very painful injection, and children hate the injections. Canakinumab is given monthly and has biologic activity for three months. There is concern among some pediatric rheumatologists that if a serious adverse event occurs in a canakinumab-treated patient, it may worsen because there’s no way to remove the drug from the body. Rilonacept is given every two weeks and avoids the daily, painful injections of anakinra and does not have biologic activity of three months. It may be preferred by some pediatric rheumatologists.”

“This is an exciting study on rilonacept as it is offering children with systemic onset juvenile idiopathic arthritis a new option for treatment,” says Patience White, MD, the vice president for Public Health Policy and Advocacy for the Arthritis Foundation.

“Due to the relative safety of this new therapy, it will be important to have more experience with rilonacept to learn where this therapy fits into the current medical therapies for systemic onset idiopathic juvenile arthritis and follow up on the possible side effects,” says Dr. White, who is also a professor of medicine and pediatrics at the George Washington University School of Medicine and Health Sciences in Washington, D.C.  

Tim Beukelman, MD, associate professor of pediatrics, in the division of rheumatology at University of Alabama at Birmingham, agrees that rilonacept would be a useful addition to the sJIA arsenal.

“This study provides additional high-level evidence that IL-1 is a very important signaling molecule in systemic JIA,” says Dr. Beukelman. “Medications that block IL-1 or IL-6 should usually be used very early in the disease course to achieve the best outcomes. We currently cannot predict which patient will do best with which specific drug, so rilonacept could be a valuable treatment option for a group of children with systemic JIA.

“Our field is excited about the effectiveness of these new biologics for the treatment of systemic JIA,” adds Dr. Beukelman. “The clinical responses are very impressive and will allow us to decrease the use of steroids, which have many unavoidable adverse effects.”