SAN DIEGO — The biosimilar CT-P13 was comparable to infliximab in patients with rheumatoid arthritis for all disease-related and safety assessments in a 1-year extension of the PLANETRA study.
"CT-P13 was effective and well tolerated over 2 years," said lead investigator Dae-Hyun Yoo, MD, from Hanyang University in Seoul, South Korea. "Switching from infliximab to CT-P13 was feasible, safe, and effective."
CT-P13 was recently approved by the European Medicines Agency (EMA). It is not clear when it will be approved in the United States.
"Biosimilars is one of the hottest areas in rheumatology," said Eric Matteson, MD, from the Mayo Clinic in Rochester, Minnesota, who was not involved in this study. "What we can say from the studies of CT-P13 and infliximab is that the 2 drugs are definitely comparable, and the safety signals are as expected."
This was one of several studies on biosimilars presented here at the American College of Rheumatology (ACR) 2013 Annual Meeting.
PLANETRA was a 54-week randomized double-blind parallel-group study that demonstrated equivalence in efficacy and safety for CT-P13 and infliximab in patients with rheumatoid arthritis. In the trial, all patients also received methotrexate and folic acid every 8 weeks.
The 48-week open-label phase 3 extension of PLANETRA involved 302 patients. In the maintenance group, 158 patients were maintained on CT-P13; in the switch group, 144 patients switched from infliximab to CT-P13.
At weeks 54, 78, and 102, disease control — measured using ACR scores, which indicate the degree of improvement in rheumatoid arthritis — was similar in the 2 groups.
Table. Response Rates With CT-P13
|Response Rate||Maintenance Group, %||Switch Group, %|
Changes in disease activity score with 28 joint counts from baseline were also comparable in the 2 groups.
About 50% of patients in each group developed antidrug antibodies to the respective drugs by 2 years. Antidrug antibody positivity did not increase significantly in the extension study, when both groups were receiving CT-P13, Dr. Yoo reported.
"We don't know the impact of antibodies on safety and efficacy, and the data do not address this. This is important because the long-term effects might not be seen for years," Dr. Matteson said.
At 2 years, the proportion of patients with 1 or more treatment-emergent adverse events was similar in the maintenance and switch groups (53.5% vs 53.8%). More infusion-related reactions were reported in the maintenance group (10 vs 4). One patient in the maintenance group and 4 in the switch group developed cancer. There were no reports of tuberculosis.
"There are tremendous economic implications of this study, which shows that a biosimilar is comparable to infliximab, which is off patent," said session moderator and program chair Chester Oddis, MD, from the University of Pittsburgh.
However, "the FDA approval process involves demonstrating appropriate interchangeability" — switching back and forth — between a biologic and a biosimilar with no loss of immunogenicity, which these data do not, he explained. "When payers get this information, there may be a move away from biologic therapy. It will be fascinating," Dr. Oddis said.
This study was sponsored by Celltrion. Dr. Yoo reports financial ties with the company. Dr. Matteson reports financial relationships with Ardea Biosciences, Celgene, Genentech, Biogen Idec, Hoffman La-Roche, Janssen, Mesoblast, Novartis, Pfizer, UCB Pharma, and the Rheumatology Research Foundation. Dr. Oddis has disclosed no relevant financial relationships.
ACR 2013 Annual Meeting: Abstract L1. Presented October 29, 2013.
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Cite this: Biosimilars Gaining Ground in Rheumatoid Arthritis - Medscape - Nov 04, 2013.