D3.179 - Safety of 300IR liquid sublingual immunotherapy of cat allergen extract for respiratory allergy to cat dander: a post-marketing experience

After house dust mites and pollens, cat dander allergen is the third leading cause of respiratory allergy and is associated with a significant disease burden. However, cat allergy is often not managed appropriately. Allergen immunotherapy is the only currently available causal/etiologic treatment for respiratory allergy. A liquid sublingual immunotherapy (SLIT) of cat allergen extract 100IR/mL has been on the market in 22 countries for the past +30 years. In France, the product is registered as Allergènes Préparés Spécialement pour un seul Individu (APSI) and Cat SLIT-liquid is available at 300IR/mL since November 2021. Here we present the post-marketing safety experience with Cat SLIT-liquid in France with a specific focus on the 300IR formulation.

Safety data consisting of Individual Case Safety Reports (ICSRs) have been collected from spontaneous reporting and post-marketing studies through a pharmacovigilance system.

As of November 2024, it is estimated that 50 900 patients (13 446 patients less than 18 years old) have been exposed to Cat SLIT-liquid in post-marketing settings in France, including 19 422 (4935 < 18 years old) exposed to Cat SLIT-liquid 300IR. The cumulative rate of ICSRs (i.e. number of case reports/total number of patients exposed) was 1.87% (950/50 900) for Cat SLIT-liquid with a reporting rate equaling 1.37% (265/19 422) for Cat SLIT-liquid 300IR. Most adverse drug reactions were application-site reactions such as mouth oedema or throat irritation. Of all cases reported with Cat SLIT-liquid, 49 (5.1%) were serious including 32 (3.4%) considered related to the product. Among these, 15 (5.7%) serious cases (with 14 (5.3%) considered related to the product) were reported with Cat SLIT-liquid 300IR. In patients < 18 years old, there were 13 serious ICSRs (including 10 considered related) with Cat SLIT-liquid and of these, 6 serious cases (5 considered related) were reported with Cat SLIT-liquid 300IR. No serious adverse events such as anaphylactic reactions, severe local site reactions, and eosinophilic esophagitis (EoE) were reported with Cat SLIT-liquid 300IR.

The safety profile of Cat SLIT-liquid 300IR is consistent with that of the broader Cat SLIT-liquid product line. With serious adverse events occurring in 5.7% of cases and no reports of high-risk reactions like anaphylaxis, severe local allergic reactions, or EoE, Cat SLIT-liquid 300IR appears to be a well-tolerated treatment option for patients with respiratory allergy to cat.