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Abatacept does not increase malignancies in rheumatoid arthritis patients

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – Abatacept, an agent that modifies the costimulatory signal required for T-cell activation, does not increase malignancy rates in patients with rheumatoid arthritis (RA), according to researchers reporting on clinical trial safety data.

Abatacept is effective in RA, but its potential risk for rare adverse events such as malignancies is not yet clear – and as lead author Dr. Theresa A. Simon from Bristol-Myers Squibb, Hopewell, New Jersey and colleagues point out, “The risk of malignancy is of particular importance in patients who receive immunomodulatory therapies.”

For their report in the December Annals of the Rheumatic Diseases, the investigators analyzed data from seven clinical trials involving 4134 abatacept-treated RA patients in Europe and North America.

The age- and sex-adjusted incidence ratio of total malignancies was 0.61 per 100 person-years with abatacept treatment, compared with 0.63 per 100 person-years in placebo groups.

When the rate of total malignancies in the abatacept cohorts was compared with pooled incidence ratios from large RA cohorts on non-biological disease-modifying antirheumatic drugs (DMARD), the summary standardized incidence ratio (SIR) was 0.68, indicating that the overall risk of cancer was not significantly increased in abatacept-treated patients.

The SIR comparing cancer incidence ratios in abatacept-treated RA patients with incidence ratios in the general population were 0.82 for total malignancy, 0.41 for breast cancer, 0.32 for colorectal cancer, 1.51 for lung cancer, and 2.17 for lymphoma, none of which were statistically significant.

“These data add to the continuing body of evidence evaluating the safety of abatacept and suggest that the observed number of malignancies is within the range of expected malignancies based on RA cohorts on a background of non-biological DMARD treatment,” the researchers conclude.

“The overall safety of abatacept with respect to malignancies will continue to be monitored as part of a post-marketing surveillance program,” they add.

This study, and all the studies analyzed herein, were funded by Bristol-Myers Squibb, which markets abatacept as Orencia.

Ann Rheum Dis 2009;68:1819-1826.