D3.201 - Subcutaneous immunotherapy with a depigmented cat allergoid is safe in patients with cat allergy and beneficial for mental health in adolescents

Allergen immunotherapy is the only causal treatment for respiratory allergies. While subcutaneous immunotherapy (SCIT) with unmodified allergen extracts is often accompanied with side effects, SCIT with modified extracts represents a promising alternative. This study aimed to collect safety data on a depigmented cat allergoid in patients with cat allergy.

Adolescent and adult patients suffering from cat-induced allergic rhinitis/rhinoconjunctivitis with/without asthma were enrolled in a prospective, multicenter, non-interventional post-authorization safety study (NIS-PASS) in Germany. Patients were treated as recommended, either at 5 visits (up-dosing within 2 weeks + 2 maintenance doses) or at 3 visits (up-dosing in 30 minutes + 2 maintenance doses). Adverse events (AEs) within 2 days of injections were documented in electronic diaries and classified by investigators. Quality of life (QoL) was assessed using the SF-12 health survey.

From May 2022 to January 2024, 101 patients were enrolled. Approximately 50% experienced AEs, without fatalities or epinephrine use. One patient had a serious Grade 2 systemic reaction (SR) and recovered within 30 minutes after symptomatic treatment. Most AEs were local (approx. 65%) and mild, with around 2/3 being delayed reactions. SR, mostly Grade 2, were equally distributed between dosing regimens. No SR of Grade 3 or 4 occurred. QoL assessment showed marginal differences in physical health, but adolescents on the quick regimen experienced about a 20% improvement in mental health (p=0.068).

SCIT with a depigmented cat allergoid was safe and well tolerated. Although not statistically significant, the increase in mental health suggests a benefit of the quick up-dosing regimen in adolescents.