MELBOURNE, Australia — The anti-interleukin-5 monoclonal antibody mepolizumab is indicated for use in patients with relapsing refractory eosinophilic granulomatosis with polyangiitis (EGPA), but a new study suggested that starting treatment soon after diagnosis could double remission rates and reduce organ damage.

Speaking at the 22nd International Vasculitis Workshop (IVW) 2026, Roberto Padoan, MD, PhD, rheumatologist at the University Hospital of Padova in Padova, Italy, presented data from the multicenter retrospective MEPEARL cohort study of very early mepolizumab in EGPA.

The study involved 587 adults with EGPA with a median disease duration of 5 years from nearly 40 referral centers across Europe. Around half the participants were treated with 100 mg mepolizumab every 4 weeks, and half received a 300-mg dose every 4 weeks. In total, 116 patients in the cohort had started mepolizumab within 3 months of their initial diagnosis.

Prompted by observations that patients who started treatment early after diagnosis appeared to be doing better than those who started later in the disease course, researchers sought to answer the question of whether initiating treatment earlier, rather than waiting until after relapse, could improve long-term outcomes.

At baseline, patients who started mepolizumab early showed higher disease activity levels than those treated later, with a median Birmingham Vasculitis Activity Score (BVAS) of 5 in the early starters compared to 3 in the later starters.

However, the study found those initiated very early were 2.4 times more likely to go into remission — defined as a BVAS score of 0 on a prednisone dose of ≤ 4 mg/d — over the 24-month follow-up compared with patients who started mepolizumab 2 years or more after diagnosis.

This was evident even after adjusting for potential confounders such as age, sex, type of antineutrophil cytoplasmic autoantibody present, baseline disease severity, and prednisone use. In the analysis adjusting for these factors, 3 months after starting early treatment, 19% of patients were in remission, and 24 months after initiating treatment, that figure increased to 56.6% of patients.

When researchers looked at the effect of starting mepolizumab between 3-12 months or 12-24 months after diagnosis on remission rates, they saw only intermediate benefits compared with starting after 24 months, “so the magnitude was significantly higher in those treated in the first 3 months,” Padoan told the conference.

The researchers noted that late starters on mepolizumab responded more quickly to the treatment and had higher remission rates in the first 10-12 months after treatment. But after that point, remission rates were significantly higher among the early-treated group. “Looking at remission rates over time, you can see that late starters respond quickly, so less probably severe disease and more remission over time, but there is a crossover point,” Padoan said.

Both Doses Similar in Remission Rates, Lower Steroid Use

Patients who started mepolizumab within 3 months of diagnosis were also more than three times more likely to be steroid-free at 12 months after initiating treatment compared with those who started the drug 24 months after diagnosis. Researchers also saw that the early-starting patients had significantly lower odds of new damage accrual at 24 months after starting treatment compared with late starters.

“Starting earlier means better disease control, and it’s more easy to withdraw the glucocorticoid,” Padoan told Medscape Medical News. That earlier cessation of glucocorticoids was also likely to be a contributing factor to the lower levels of damage accrual seen in the early mepolizumab group. “The main leading cause of damage accrual in these types of patients is the glucocorticoid exposure, because they develop diabetes, hypertension, cataract, osteoporosis,” he said.

Patients who started early on the 100-mg dose showed similar trajectories of remission and glucocorticoid cessation to those who started early on the 300-mg dose. “The benefit of early treatment is identical, whether you treat the patient with 100 mg or 300 mg,” Padoan said, pointing out that those who were put on the lower dose likely had less severe disease at baseline.

Padoan said the results pointed toward a shift in the treatment paradigm for EGPA. “You target the eosinophil part of the disease with mepolizumab, then you target the autoimmune disease with the immunosuppressants, and then combining together it leads to better control of the disease and probably less glucocorticoid over time,” he said.

Commenting on the data, Sebastian Unizony, MD, from Massachusetts General Hospital and Harvard Medical School in Boston, told Medscape Medical News that for many years, studies of mepolizumab had focused on relapsing patients and that the data hadn’t been available for its efficacy in new-onset disease. “To me, the most important part of that abstract is damage — if you introduce it early, [you] control the disease, and then you get less damage,” he said.

However, both Padoan and Unizony acknowledged that the cost of biologics such as mepolizumab could be an issue. “But again, if you have an upfront use, that maybe can save the cost for future relapses and damage accrual,” Padoan said. “For example, the cost of the treatment for diabetes is high; the cost for bone fractures related to osteoporosis is very high.”

The study was independently supported. Padoan declared honoraria and consultancies with several pharmaceutical companies, including GlaxoSmithKline, the manufacturer of mepolizumab.