Regulatory Decision Summary for Acarizax

After evaluation of the submitted data, Health Canada authorized the age group expansion of the indication as following:

“Acarizax (Standardized Allergen Extract, House Dust Mites (D. farinae and D. pteronyssinus) Sublingual Tablet) is indicated as allergy immunotherapy for the treatment of moderate to severe house dust mite-induced allergic rhinitis, with or without conjunctivitis, in adolescents and adults 12 to 65 years of age confirmed by a positive skin prick test and/or in vitro testing for D. farinae or D. pteronyssinus IgE antibodies”.

House dust mite (HDM)-induced allergic rhinitis (AR) is caused by reactions to HDM allergens. Acarizax tablet contains HDM allergen extract as the medicinal ingredient. The mechanism for the treatment of HDM-induced AR with Acarizax is largely unclear. It is hypothesized that long-term daily exposure to a small amounts of HDM allergen may change the way the immune system reacts to HDM allergen and somehow result in improvement in clinical symptoms of HDM-induced AR. Acarizax tablet is sublingually administrated, i.e. placing the tablet under the tongue for a few seconds before swallowing. This treatment method is classified as sublingual immunotherapy (SLIT). Current treatment of AR is mainly by allergen avoidance and symptomatic relieving medications. SLIT is an addition to the treatment tools for AR.

The authorization of the proposed age-group expansion of the indication for Acarizax was primarily based on two clinical studies. One was a randomised, double-blind, placebo-controlled study in North America to evaluate the efficacy and safety of Acarizax with 1,482 patients (12 years of age or older). The other study was a single-arm, open-label study conducted in Europe to investigate safety and tolerability in once-daily treatment for 28 days weeks with HDM SLIT-tablet (12 SQ-HDM) in 253 adolescents (12 to 17 years of age).

Based on data submitted, clinical efficacy of Acarizax in adolescent patients appears comparable to that in adult patients. The safety assessment of the product did not identify clinically concerning difference between adolescents and adults. The vast majority of patients in the clinical studies experienced at least one adverse reaction. The very common adverse reactions (>10%) were throat irritation, oral pruritus, ear pruritus, lip swelling, swollen tongue, nausea, glossodynia, pharyngeal swelling, tongue ulceration, mouth ulceration and abdominal pain upper. Oral pruritus, throat irritation, and ear pruritus were the most frequently reported with a reporting rate from 40% to 73%. The reporting rate in tongue ulceration, mouth ulceration or abdominal pain upper was higher in adolescents than that in adults. Reoccurrence of the same adverse event was commonly reported in most patients, especially for those that occurred at or close to the application sites. Most reported adverse events were mild or moderate in severity. No specific safety concerns were identified in adolescents. 

In conclusion, the benefit/risk profile (balance between benefit and harm) of Acarizax treatment in adolescents with AR/C is considered favorable on the basis of the available information in the submission package.