Occurrence of Systemic Allergic Reactions and Severe Swellings with SQ HDM SLIT-tablet

RATIONALE: Systemic allergic reactions and severe swellings are potential risks during at-home treatment with sublingual allergy immunotherapy (SLIT). This abstract presents treatment-related systemic allergic reactions and severe swellings from 2 double-blind, randomized, placebo-controlled trials with the SQ house dust mite (HDM) SLIT-tablet (ALK, Denmark) conducted in North America (trial A, clinicaltrials.gov: NCT01700192) and Europe (trial B, EudraCT: 2011-002277-38).

METHODS: Subjects (N=741 in trial A, N=318 in trial B) with moderate-to-severe HDM allergic rhinitis were treated with the SQ HDM SLIT-tablet (dose of 12 SQ-HDM/day) for up to 1 year. Treatment-related adverse events are summarized.

RESULTS: In trial A there was 1 systemic allergic reaction (non-serious, assessed as moderate, occurring on day 1, treatment: epinephrine IM and desloratadine/pseudoephedrine) and 1 severe swelling (nasal edema, non-serious, day 66, treatment: antihistamine). In trial B, there were no systemic allergic reactions and 2 severe swellings (lip edema, non-serious, day 274, treatment: antihistamine; and edema mouth, non-serious, day 15, treatment: none).

CONCLUSIONS: In the 2 phase III trials in North America and Europe, 1 non-serious, treatment-related systemic allergic reaction was reported. This event occurred on day 1 of treatment with the HDM-SLIT tablet within the recommended 30 minutes observation period at the clinic. There were 3 events of severe swelling, none of these resulted in airway compromise. All events were assessed as non-serious. Overall, this is a prevalence of 0.1% for systemic allergic reactions and 0.3% for severe swellings. Treatment with the SQ HDM SLIT-tablet appears to be safe for at-home administration.