SAN ANTONIO — Adding the selective costimulatory modulator abatacept to methotrexate in patients with rheumatoid arthritis who do not respond adequately to methotrexate alone resulted in “robust clinical efficacy” that persisted for 2 years, according to the findings of an extension study.
Among patients who completed 2 years of treatment, response rates were similar at 2 years to what they were at 1 year, Joel M. Kremer, M.D., said in a poster session at the annual meeting of the American College of Rheumatology. (See chart.)
In the initial double-blind phase of the trial, 115 participants whose mean age was 55.6 years and whose mean disease duration was 10 years were randomized to receive intravenous abatacept (10 mg/kg monthly) plus methotrexate in a stable dose of 10 to 30 mg/week for 1 year.
Those who completed the yearlong blinded phase were eligible to enroll in the long-term open trial, which used a fixed dose of abatacept (about 10 mg/kg) along with methotrexate.
A total of 84 patients entered the open phase and 75 completed the full 2 years. High rates of retention in the trial, along with improved ACR scores, demonstrated consistent and sustained clinical efficacy, said Dr. Kremer, director of research at the Center for Rheumatology, Albany, N.Y.
In addition to the standard American College of Rheumatology (ACR) 20, 50, and 70 responses, ACR 90 responses were assessed. This score was achieved by more than 13% of patients at year 1 and almost 15% at year 2.
During the double-blind phase of the study, the most common adverse events were nasopharyngitis, headache, nausea, and cough. There were no new emerging safety issues during the long-term extension phase, he said.
Abatacept is the first in a new class of agents that inhibit the full activation of T cells. It blocks the engagement of the costimulatory molecule CD28, resulting in the inhibition of cytokines that activate inflammatory cells.
Dr. Kremer disclosed that he receives research grants and consulting fees from multiple sponsors, including Bristol-Myers Squibb Co., the manufacturer of abatacept.
