Abatacept does not reduce the number of new gadolinium-enhancing lesions on MRI in patients with relapsing-remitting multiple sclerosis (MS), according to results from the double-blind, randomized, placebo-controlled phase II ACCLAIM study published online ahead of print August 1 in Multiple Sclerosis.
In the ACCLAIM (A Cooperative Clinical Study of Abatacept in MS) study, 42 patients who received abatacept (Orencia) developed a mean of 0.43 new gadolinium-enhancing lesions by week 24, compared with 1.66 lesions for 20 placebo-treated patients. None of the secondary MRI end points (ie, lesion volume change and percent brain volume change) and clinical end points (ie, changes in MS Functional Composite score, Expanded Disability Status Scale [EDSS], and annualized relapse rate) at 24 weeks differed significantly between the groups. The rate of patients who met criteria for no evidence of disease activity or its components (ie, no EDSS progression, no clinical exacerbations, and no new gadolinium-enhancing MRI lesion) from week 8 and before week 28 did not differ between the groups.
During a 28-week extension phase in which the groups switched treatments, patients who switched from abatacept to placebo had a greater number of gadolinium-enhancing lesions than did those who switched from placebo to abatacept (1.25 vs 0.60, respectively), but the difference was not statistically significant.
Abatacept, which is approved for the treatment of rheumatoid arthritis and juvenile idiopathic arthritis, is a CTLA4 immunoglobulin fusion protein that inhibits the activation of T lymphocytes by blocking the CD28-B7 costimulatory pathway. It was thought to have potential to reduce immune-mediated disease activity in relapsing-remitting MS because T lymphocytes have been implicated in its pathogenesis.
The investigators closed enrollment for the trial early because of slow accrual. The 65 patients who were enrolled in the trial were about half of the population considered to be required (ie, 123) to demonstrate a treatment effect of 50% reduction of new gadolinium-enhancing MRI lesions.
Samia J. Khoury, MD
—Jeff Evans