Efficacy and safety of specific immunotherapy with a modified mite extract

Background: In specific immunotherapy (SIT), modified extracts have been used to allow safe administration of higher allergen doses. Schedules reaching maintenance doses in approximately 1 month, which may have greater efficacy, have even been proposed. Aims: To assess the safety and efficacy of SIT with modified (depigmented and polymerized) Dermatophagoides pteronyssinus extract in the treatment of allergic rhinitis. Material and methods: Fifty patients with moderate-to-severe persistent allergic rhinitis and who were monosensitized to Dermatophagoides were included in this controlled, pragmatic, 1-year open study. The patients were randomly allocated to receive treatment with a Dermatophagoides pteronyssinus 100% modified allergen vaccine (active group, n = 25) or pharmacological treatment only (control group, n = 25). All SIT-related adverse reactions were recorded. Efficacy was assessed primarily through the results of nasal allergen challenges, through visual analog scale (VAS) and symptom scores. Results: In SIT-treated patients, significant improvements were found in symptom scores (mean reduction > 40 %), VAS scores (mean improvement > 20%) and nasal challenges (mean increase in allergen concentration threshold > 500%). For symptom and VAS scores, statistically significant differences between control and SIT-treated patients were recorded at 12 months. In nasal challenges statistically significant differences were observed as early as at 6 months. Control patients showed no significant differences during the study period. Local reactions were observed in 28% of SIT-treated patients (total 24 reactions). There was only one immediate grade I systemic reaction, which was successfully treated with an antihistamine. Conclusions: SIT with this modified extract appears to be a relatively safe treatment, which can rapidly improve nasal allergenic tolerance, reduce symptom scores and improve subjective self-evaluation measured through VAS, reflecting a general improvement in patients’ well-being.