D2.172 - Subcutaneous immunotherapy with a depigmented cat allergoid in patients with cat allergy is safe and results primarily in delayed local reactions

Allergen immunotherapy (AIT) is the only causal treatment of respiratory allergies. Whereas subcutaneous immunotherapy (SCIT) with native allergen extracts is often accompanied with high incidence of side effects, SCIT with modified allergen extracts represents a promising, safe treatment alternative. The purpose of the current study was to collect data on the safety of a depigmented cat allergoid in patients with cat allergy.

Patients allergic to feline epithelia and suffering from allergic rhinitis/rhinoconjunctivitis with or without controlled asthma were enrolled into a prospective, multi-center, non-interventional post authorization safety study (NIS-PASS) in Germany. Patients were treated in accordance with the recommended dosing schemes of the depigmented cat allergoid and treated either at 5 visits (conventional up-dosing regime within 2 weeks / 10 weeks total observation period) or at 3 visits (30 minutes up-dosing regime / 8 weeks total observation period). Following treatment with the depigmented cat allergoid, patients used electronic diaries to document adverse events (AEs) experienced within 2 days following subcutaneous injections, and investigators evaluated and classified observed AEs.

From May 2022 until January 2024, 101 patients were enrolled into the currently still ongoing study. Overall, approximately 50% of treated patients experienced AEs. No fatalities occurred, and no epinephrine was used. No systemic reactions of Grade 3 and 4 were observed. One patient experienced a serious adverse event (shortness of breath, systemic reaction Grade 2) upon first injection and recovered within 30 minutes upon treatment with one single dose of a short-acting β₂ adrenergic receptor agonist  and oral antihistamine. Of the related AEs, the majority (approx. 65%) were local reactions, of which about 2/3 presented as delayed local reactions. The majority of systemic reactions were classified Grade II equally distributed between both dosage schedules.

SCIT with a depigmented cat allergoid was safe and well tolerated by patients with cat allergy.