RESEARCH - Enbrel does not appear to diminish antibody recall response to immunization

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LabNews.com

07/23/2004

Treatment with etanercept does not appear

to diminish antibody recall response to immunization, study finds

FaxWatch - Treatment with etanercept does not have a significant

influence on the antibody response to pneumococcal vaccine in patients

with psoriatic arthritis, researchers reported.

A group of 205 patients with psoriatic arthritis were stratified

by methotrexate use and randomized to receive placebo or 25 mg of

etanercept twice weekly for four weeks. Both groups received a 23-valent

pneumococcal vaccine, and a poor vaccine response was defined as a

two-fold or greater increase in antibody titer to three or fewer

antigens.

Mean pre-vaccination antibody titers ranged from 1.63 to 6.44

mcg/mL for the five antigens tested. Mean post-vaccination levels ranged

from 4.55 to 24.91 mcg/mL.

The proportion of patients who had a poor antibody response was 60

percent in the etanercept group and 50 percent in the placebo group.

Patients treated with methotrexate had a significantly higher incidence

of poor response than those not receiving methotrexate: 77 percent

versus 37 percent.

For the entire group, 67 percent of the patients achieved a

two-fold or greater increase in antibody titer to two or more antigens

and 47 percent achieved a four-fold increase. The mean number of

antigens to which patients showed a two-fold or greater increase in

antibody titer was 2.7.

Logistic regression indicated that methotrexate use and age were

predictors of poor response. There was no evidence that the addition of

etanercept to methotrexate treatment further reduced the response.

" It is rational to presume that patients treated with etanercept

will, in general, have a normal humoral response to a T cell-independent

antigen, " the researchers said.

In an accompanying editorial, Dr. Scheifele wrote, " One can

reasonably conclude from this study that four weeks of etanercept

treatment does not appear to diminish antibody recall responses to the

five polysaccharide antigens examined. "

However, he added that " Primary responses were not assessed, as

could have been done using a different panel of serotype antigens.

" Moreover, Dr. Scheifele noted that " whether responses to immunization

were sufficient to protect against the pneumococcal serotypes most

likely to cause infection in arthritis patients is unknown. Whether

etanercept-treated patients can respond quickly enough to airway

colonization with pneumococci to avoid subsequent pneumonia or invasive

infection is also unknown, as this scenario was not modeled by the study

design. "

The study and the editorial appeared in the July issue of The

Journal of Rheumatology.

http://www.labnews.de/en/ne_lib/ns_det.php?id=3196

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Mayo Clinic in Rochester

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