Background: Immunologically enhanced subcutaneous specific immunotherapy (SCIT) has been developed with a fast and simplified updosing phase containing equal parts of the house dust mites (HDM) Dermatophagoides pteronyssinus and Dermatophagoides farinae (Dermatophagoides mix) adsorbed on aluminum hydroxide.

Objective: To evaluate the tolerability and immunological impact of the updosing phase of this new allergen extract formulation.

Material and Methods: We performed a multicenter, open-label, single-arm, phase II/III clinical trial. The inclusion criteria were a clinical history of rhinitis/conjunctivitis due to HDM (with/without asthma) and sensitization to HDM (positive specific IgE and skin prick test). Five updosing injections of Dermatophagoides mix (300, 600, 3000, 6000, and 15 000 SQ+) were administered at weekly intervals with 1 maintenance injection (15 000 SQ+) 2 weeks after the last updosing injection. Two days after each visit, patients were contacted by telephone to follow up on any adverse events. IgE-blocking factor, IgG4, and immediate skin reactivity were evaluated.

Results: The sample comprised 102 patients (mean [SD] age, 29.3 [7.7] years; male, 52.9%). There were 117 adverse drug reactions (ADR): 101 were local, regardless of reaction size, in 48 (47.1%) patients and 7 were systemic (all grade I) in 5 (4.9%) patients. All ADRs were mild, except for 1, which was moderate. Six weeks of treatment led to statistically significant increases in IgE-blocking factor and IgG4, as well as a significant reduction in immediate skin reactivity.

Conclusion: This new updosing phase of Dermatophagoides mix–based immunotherapy had a good tolerability profile and induced a significant immunological effect.

Key words: Specific immunotherapy. Allergens. House dust mites. Antigens. Immune response. Subcutaneous injection. Skin reactivity. Tolerability assessment.