Efficacy and safety of specific immunotherapy with a modified mite extract

Abstract

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.