Abatacept Demonstrates Long-Term Safety in Rheumatoid Arthritis

Emma Hitt, PhD

November 08, 2010

November 8, 2010 (Atlanta, Georgia) — Results from an integrated analysis of more than 12,000 patient-years of safety data demonstrate that abatacept is generally well-tolerated in patients with rheumatoid arthritis (RA).

The analysis was performed by Marc C. Hochberg, MD, MPH, from the Department of Medicine at the University of Maryland, in Baltimore, and colleagues, who presented their findings here today at the American College of Rheumatology 2010 Annual Meeting.

Abatacept is a fusion protein composed of a modified Fc portion of human immunoglobulin G1 fused to the extracellular domain of human cytotoxic T-lymphocyte-associated antigen 4. It is currently approved for treating moderate to severe rheumatoid arthritis and juvenile idiopathic arthritis in patients 6 years of age and older.

Marc C. Hochberg, MD, MPH

The current analysis sought to evaluate the long-term safety of abatacept and to detect rare events. The researchers classified data from 8 clinical trials of abatacept into short-term and long-term periods.

A total of 4149 patients were included in the cumulative period, including 1165 patients with at least 5 years of exposure. A total of 3173 patients representing 2331 patient-years were included in the short-term period, and 3256 patients with 9752 patient-years were included in the long-term period.

Dr. Hochberg and colleagues found that exposure to abatacept over the 7-year time period was not associated with an increased incidence of serious adverse events.

The most common adverse events were infections requiring hospitalization, which occurred at an incidence of 2.64 per 100 patient-years (95% confidence interval, 2.35 - 2.95 per 100 patient-years). The most common serious infections included pneumonia (0.46/100 patient-years), urinary tract infection (0.2/100 patient-years), and cellulitis (0.18/100 patient-years).

Few opportunistic infections were observed, with an incidence of 0.36/100 patient-years. A total of 8 tuberculosis cases were reported. Nonmelanoma skin cancer occurred at an incidence of 0.73 per 100 patient-years, and solid tumors occurred at an incidence of 0.59 per 100 patient-years.

According to Dr. Hochberg, the safety profile of abatacept was stable as exposure duration increased, given that the long-term and cumulative periods were generally consistent with those in the short-term period.

"These findings demonstrate that there are no new adverse events identified in the long-term open-label extension studies," he told Medscape Medical News. "Patients who respond to and tolerate abatacept do not have an increased risk of long-term side effects," he added.

Independent commentator Michael Schiff, MD, from the Denver Arthritis Clinic, in Colorado, described these long-term safety data as very important and noted that this study adds to other long-term studies, giving clinicians confidence about the long-term safety of this agent.

"The good news is that there are no new signals," Dr. Schiff told Medscape Medical News. "The message to clinicians is that the gain that was seen in randomized controlled trials continues in long-term extension studies, long-term follow-up, and safety databases."

Dr. Hochberg reports receiving consulting fees from Abbott Laboratories, Amgen Inc, Bristol-Myers Squibb, Genentech, Biogen IDEC, Roche, and UCB, Inc. Dr. Schiff is a consultant to Bristol-Myers Squibb but was not involved in the current research.

ACR 2010 Annual Meeting: Abstract 390. Presented November 8, 2010.

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