House dust mite immunotherapy shows efficacy in allergic overlap syndrome

LOUISVILLE, Ky. — Allergen-specific immunotherapy showed efficacy among patients with atopic and contact dermatitis overlap syndrome, according to results of a pilot study.

The results were presented at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting.

“The treatment of atopic dermatitis in some cases is very challenging, especially for patients with overlap syndrome when atopic dermatitis and contact dermatitis both exist,” Yuriy Bisyuk, MD, PhD, DrMedSc, professor in the department of dermatovenereology, allergology, clinical and laboratory immunology at Shupyk National Healthcare University of Ukraine in Kyiv, Ukraine, said during his presentation. “I have a lot of patients who have both atopic dermatitis and contact dermatitis and maybe 5 or 10 years ago, I found that patients who took allergen-specific immunotherapy had benefits, so we conducted clinical trials with the Immunology Research Institute of New England.”

The pathophysiology of atopic dermatitis in the chronic phase is very similar to that of contact dermatitis, Bisyuk said, but if you treat patients with atopic dermatitis without knowing they also have contact dermatitis, patients will have persistent exacerbation of their disease.

“Approximately 30% of patients with atopic dermatitis do really have contact allergy, so it’s very important to remember this,” he said.

Bisyuk and colleagues conducted a randomized, double-blind, placebo-controlled study that included 81 patients aged 18 to 60 years with atopic and contact dermatitis with sensitization to house dust mites. All patients had a SCORAD index of at least 15 points and had their contact allergy confirmed by skin patch tests.

Of the 71 patients who completed the study, 36 patients received subcutaneous allergen-specific immunotherapy with house dust mite extracts and 35 received placebo. All patients also could receive standard therapy of daily emollients and topical corticosteroids.

Reduction in SCORAD by more than 12 points between patients assigned active treatment vs. placebo after 6 months of treatment served as the study’s primary endpoint.

The most common contact allergens identified in the cohort included formaldehyde (26%), nickel sulfate hexahydrate (22%) and cobalt chloride hexahydrate (13.6%), among others.

After 1 month of treatment, researchers did not observe a difference between the two groups. However, by month 3, the difference began to emerge, with a two-times lower SCORAD index in the active vs. placebo group by month 6.

Overall, the SCORAD index dropped from 26.3 ± 4.9 at baseline among those on active treatment to 9.5 ± 1.9 at month 6, compared with 24.5 ± 3.7 to 15.6 ± 2.4 in the placebo group.

Thirty patients from the active treatment group experienced a decrease in their SCORAD index of at least 12 points, which was significantly more than the 19 patients who experienced a drop in the placebo group (chi squared, 5.71; P < .017).

Researchers also reported a decrease in the number of contact allergen exacerbations in the last 3 months, with 3.9 ± 0.5 exacerbations in the placebo group vs. 2.1 ± 0.4 in the treatment group at month 6 (P < .05).

“This pilot study confirms that allergen-specific immunotherapy may be effective in the overlap syndrome of atopic and contact dermatitis,” Bisyuk said. “It appears that allergen-specific immunotherapy reduces sensitization to house dust mites, possibly resulting in the restoration of the integrity of the epidermal barrier.

“A decrease in the activity of the type 2 immune response probably also leads to a decrease in the activity of delayed-type contact hypersensitivity, seen with a decrease in the number of contact allergy exacerbations,” he added.