CHICAGO – Discontinuing methotrexate for 2 weeks in patients with RA starting the day they receive the seasonal influenza vaccine significantly improves the vaccine’s immunogenicity without aggravating disease activity, Kevin L. Winthrop, MD, reported at the annual meeting of the American College of Rheumatology.
“I think this is potentially clinically practice changing because now there are two studies showing the same thing,” said, a professor of public health and preventive medicine at Oregon Health & Science University, Portland.
Based upon these prospective randomized studies, which he conducted together with investigators at Seoul National University in South Korea, initiating a 2-week halt of methotrexate on the day the influenza vaccine is given to patients with RA is now his routine practice, and he recommends other physicians do the same.
The first prospective, randomized trial included 199 RA patients on stable doses of methotrexate who were assigned to one of four groups in conjunction with seasonal influenza vaccination. One group continued their methotrexate as usual, the second stopped the drug for 1 month prior to vaccination and then restarted it at the time of vaccination, the third group halted methotrexate for 2 weeks before and 2 weeks after vaccination, and the fourth suspended methotrexate for 4 weeks starting on the day they got their flu shot. Everyone received trivalent influenza vaccine containing H1N1, H3N2, and B/Yamagata.
The lowest rate of satisfactory vaccine response as defined by at least a 300% titer increase 1 month after vaccination occurred in the group that continued their methotrexate as usual. The group that halted the drug for 2 weeks before and 2 weeks after influenza vaccination had a 51% satisfactory vaccine response against all three antigens, compared with a 31.5% rate in the methotrexate-as-usual group. RA flare rates ranged from 21% to 39% across the four study arms, differences that weren’t statistically significant ().
Next Dr. Winthrop and his colleagues conducted a confirmatory prospective, multicenter, randomized trial in which they sought to nail down the optimal duration and timing of methotrexate discontinuation. A total of 320 RA patients on stable doses of methotrexate were assigned to halt the drug for 2 weeks starting at the time they received a quadrivalent seasonal influenza vaccine containing H1N1, H3N2, B/Yamagata, and B/Victoria strains, or to continue their methotrexate throughout.
A satisfactory vaccine response was achieved in 75.5% of the group that discontinued the drug, significantly better than the 54.5% rate in the methotrexate continuers. The absolute difference in seroprotection was greater in patients who halted their methotrexate for 2 weeks after vaccination for all four antigens: an absolute 11% difference for H1N1, 16% for H3N2, 12% for B/Yamagata, and 15% for B/Victoria ().
“It does seem to be a nice strategy. The percentage of people who flared their RA during their 2 weeks off methotrexate was very low, so there seems to be a good reason to do this,” according to Dr. Winthrop.
Some rheumatologists he has spoken with initially balked at the plausibility of the results.
“I had the same thought about these studies: It doesn’t make sense to me in terms of how methotrexate works, and why we would see this effect acutely by stopping methotrexate for just 2 weeks?” he said.
But then a coinvestigator drilled down deeper into the data and came up with the explanation: The benefit in terms of enhanced flu vaccine immunogenicity through temporary withholding of methotrexate was confined to the subgroup of RA patients with high baseline levels of B-cell activation factor (BAFF). In contrast, withholding methotrexate didn’t affect the vaccine response in patients with low or normal baseline BAFF ().
“I don’t know how to check anyone’s BAFF levels. I don’t think there’s a commercial test out there. But this does help explain why we saw this observation. So I think I would still hold everyone’s methotrexate for 2 weeks. That’s how I approach it. And they may get benefit from it, and they may not,” he said.
Dr. Winthrop reported having no financial conflicts regarding the study, which was funded by GC Pharma.