medwireNews: Sirukumab monotherapy is well tolerated and has measurable efficacy in Japanese patients with rheumatoid arthritis (RA) refractory to treatment with methotrexate or sulfasalazine, researchers report.
These results “support findings from the global SIRROUND-D and SIRROUND-T studies,” and “suggest a potential role for sirukumab in RA therapy,” write the investigators in Arthritis Research & Therapy.
In their phase III trial, Benjamin Hsu (Janssen Research & Development, LLC, Spring House, Pennsylvania, USA) and co-investigators randomly assigned participants to receive treatment with the interleukin (IL)-6 inhibitor at a dose of 50 mg every 4 weeks or 100 mg every 2 weeks for a total of 1 year. Patients discontinued conventional DMARDs 4 weeks prior to commencing the trial, but could take DMARDs after 24 weeks of sirukumab treatment.
In all, 91.8% of the 61 patients given sirukumab 50 mg and 95.1% of the 61 patients given the 100 mg dose experienced adverse events (AEs), and serious AEs were reported in a corresponding 6.6% and 8.2% of participants.
The most common AEs in both groups were nasopharyngitis, injection site erythema, and injection site swelling. Grade 3 neutropenia or leukopenia occurred in seven patients (three in the 50 mg group and four in the 100 mg group), and no grade 4 events were reported.
These hematologic abnormalities are “a common feature noted in all anti-IL-6 therapy studies,” say Hsu and team.
They summarize that sirukumab monotherapy at both doses “was generally tolerable and the safety profile was dosage independent.”
In the efficacy analysis, 77.0% of patients in the 50 mg group and 72.1% of those in the 100 mg group achieved at least a 20% improvement in ACR criteria (ACR20) from baseline to week 16. ACR20 responses were seen after 2 weeks of treatment and maintained at the 1-year follow-up.
ACR50 and ACR70 response rates at week 16 were numerically lower among patients receiving sirukumab 50 mg compared with those given the 100 mg dose, at 47.5% versus 57.4% and 26.2% versus 32.8%, respectively. ACR50 and ACR70 responses were sustained over 1 year of treatment, as were improvements in disease activity and disability.
“The absence of a placebo control is a limitation for this study with respect to the absolute efficacy achieved,” say the researchers, but they note that “consistent improvement was observed in both sirukumab-treated groups in terms of the clinical signs and symptoms of RA.”
And the team concludes: “Generalizability and extrapolation of these results to routine clinical practice should be made within the context that the patients discontinued [conventional] DMARDs before study participation, in contrast to the recommended treatment modality that includes continued use of DMARDs for greater efficacy in patients with active RA.”
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