NEW YORK (Reuters Health) - Genetic variations in particular HLA and TNF gene regions predict response to methotrexate and etanercept in patients with early rheumatoid arthritis (RA), researchers report in the September issue of Arthritis and Rheumatology.
Dr. S. Louis Bridges Jr., of the University of Alabama at Birmingham, and colleagues analyzed genetic and clinical data from 457 patients who had had RA for 3 years or less. The subjects had been randomized to methotrexate (weekly), low-dose etanercept (10 mg twice weekly) or standard-dose etanercept (25 mg twice weekly).
An improvement of 50% on The American College of Rheumatology disease activity score was the main outcome measure.
Patients who had inherited two copies of the HLA-DRB1 alleles encoding the shared epitope which influences susceptibility to and severity of RA were 4.3 times more likely to show a response to standard-dose etanercept than were those with one or no copy.
In total, 76% of the patients with two shared epitope copies responded to standard-dose etanercept versus a 46% response to methotrexate. However, responses to treatment with low-dose etanercept or methotrexate did not differ significantly by the number of shared epitope copies
Among the Caucasian subjects, extended haplotypes that included the HLA-DRB1 alleles and LTA-TNF variants were also associated with treatment response, the team notes.
These results, the researchers conclude, may be of use in identifying which patients “are more likely to benefit from treatment with methotrexate or etanercept.”
Moreover, Dr. Bridges told Reuters Health that the possible “genetic influences on treatment responses in rheumatoid arthritis...should be confirmed in additional studies and in individuals of different race and ethnicity.”
Source: Arthritis Rheum 2004;50:2750-2756. [ Google search on this article ]
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