The investigational IL-6 inhibitor olokizumab fared better than placebo and was noninferior to the tumor necrosis factor inhibitor (TNFi) adalimumab (Humira) in patients with moderate to severe rheumatoid arthritis (RA) who’d had an inadequate response to methotrexate alone, according to new findings published in the New England Journal of Medicine.
The results from the phase 3, multicenter, double-blind, parallel-group, randomized, placebo- and active-comparator–controlled trial, called Clinical Rheumatoid Arthritis Development for Olokizumab (CREDO2), add to the evidence base on the drug, which was developed by R-Pharm in Russia and has been approved for use there. Last year, researchers reported results from two trials showing sustained improvements in symptoms, function, and quality of life in patients with an inadequate response to anti-TNF treatment.
Prof. Josef S. Smolen
“Once approved, olokizumab can be used in patients who have not responded well to either methotrexate or any biological disease-modifying antirheumatic drug or any JAK [Janus kinase] inhibitor in combination with methotrexate or alone,” said Josef Smolen, MD, chair of rheumatology at the Medical University of Vienna and the lead author on the study.
Researchers randomized 1,648 patients to 64 mg of olokizumab every 2 or 4 weeks, adalimumab every 2 weeks, or placebo. All patient groups continued to receive methotrexate. A total of 89.7% of the participants completed 24 weeks of treatment. By that point, 74.1% of those receiving olokizumab every 2 weeks had achieved an ACR 20 response, an improvement of at least 20% in American College of Rheumatology response criteria, including tender and swollen joints, and 71.4% in the group receiving olokizumab every 4 weeks; 69.0% in the adalimumab group; and 46.5% in the placebo group had achieved an ACR 20 response. Olokizumab benefits were also seen for Disease Activity Score in 28 joints, disability index scores, and ACR 50 responses, the researchers reported.
Approved IL-6 inhibitors tocilizumab (Actemra) and sarilumab (Kevzara) target the interleukin (IL)-6 receptor (IL-6R), but olokizumab targets a protein, glycoprotein 130 (GP130), to which the IL-6 and IL-6–receptor complex binds. This approach could offer an added benefit, Dr. Smolen said.
“Previously studied anti–IL-6 antibodies and anti–IL-6R antibodies prevent binding of IL-6 to the IL-6R,” he said. “Moreover, the amount of protein needed to inhibit IL-6 is lower compared to the approved antireceptor antibodies. Olokizumab has also been shown to be effective when given every 4 weeks in many patients, compared with the need for weekly or every-other-week applications with tocilizumab and sarilumab. From these perspectives, this novel mode of action may, indeed, provide an advantage.”
ACR 70 – an improvement of at least 70% in the ACR response criteria – was an exploratory endpoint in the trial. This response was seen in 28% of those receiving olokizumab, compared with 11% in the placebo group, but researchers cautioned that “no conclusions can be drawn from these results.”
Another drug, sirukumab, also targeted the IL-6 ligand rather than the receptor, but was rejected by regulators in 2017 because so many more deaths occurred in the treatment group than the placebo group.
Dr. Smolen noted that there are three binding sites for IL-6, but olokizumab is the first to target site 3, the binding site for GP130. Mortality concerns haven’t been seen for olokizumab. There were three serious adverse events leading to death in the olokizumab every-2-weeks group; two in the olokizumab every-4-weeks group; one in the adalimumab group; and one in the placebo group.
“The fact that olokizumab targets another site on the IL-6 molecule than sirukumab may be a reason for the difference,” Dr. Smolen said.
Still, researchers noted that the time horizon for this trial is not very long.
“The trial was conducted in a relatively small number of patients and over a short duration, especially for the assessment of rare events or events requiring longer durations of exposure,” they wrote. “Longer and larger trials are required to determine the efficacy and safety of olokizumab in patients with rheumatoid arthritis.”
Dr. Smolen said he expects R-Pharm will file for regulatory approval in the United States and Europe, outside of Russia, in the next year.
Dr. Paul Emery
Paul Emery, MD, professor of rheumatology at the University of Leeds (England) who has researched IL-6 therapy in RA, said olokizumab appears to be an effective product, but its use remains a question.
“The question is where it will fit into treatment strategies,” he said. “It’ll be very interesting.”
Dr. Emery pointed out that tocilizumab, which inhibits IL-6 by blocking the IL-6 receptor, was approved in the United States at a dosage that wasn’t optimally effective after failure with TNF inhibitors (TNFi), and wondered whether olokizumab would fare differently in this regard.
While Dr. Emery said it was important that no bad safety signal has been seen, he noted that “it’s a short-term study, and you do need to see the long-term data.”
“It seems to work at both the intervals it was tested at, 2 and 4 weeks. The unknowns are whether it will be as effective as IL-6 receptor blockers in other diseases,” such as giant cell arteritis, “and early disease, and whether it will work as well post TNFi,” he said. “It could be used as first advanced therapy for people with contraindications to TNFi, but initially the majority of its use will be after TNFi, and that’s why you need to see more data on such patients.”
He added: “The final issue will be pricing. Therefore, a positive study – but much is still unknown.”
The study was supported by R-Pharm. Dr. Smolen reports financial relationships with R-Pharm, AbbVie, Janssen, Eli Lilly, Gilead, Pfizer, and other companies. Dr. Emery reports financial relationships with AbbVie, AstraZeneca, Janssen, Pfizer, Roche, and other companies, but not olokizumab manufacturer R-Pharm.