SCIT with a high-dose house dust mite allergoid is well tolerated: safety data from pooled clinical trials and more than 10 years of daily practice analyzed in different subgroups

BACKGROUND: Efficacy of house dust mite (HDM) allergen immunotherapy (AIT) in allergic rhinitis and controlled allergic asthma has been documented in controlled trials with adults and children. However, tolerability comparing clinical development and post marketing data, particularly in different subgroups, is missing. METHODS: We performed an analysis of pooled safety data for subcutaneous AIT (SCIT) with a high-dose house dust mite allergoid from 6 randomized, controlled trials (RCT) in HDM allergic respiratory disease (ARD) and of post marketing safety data from more than 10 years including different subgroups (age, gender, asthma status). RESULTS: In all, 500 patients with ARD were treated in RCTs: 279 received the marketed dose of 1800 protein nitrogen units (PNU) high-dose HDM allergoid AIT (214 double-blind placebo controlled [HDM-DBPC], 65 children/adolescents usual care controlled [HDM-RCT(UC)]), and 221 placebo (PL). 38.8% adverse events (AEs) were observed with 1800 PNU in HDM-DBPC (31.2% PL, 35.5% HDM-ALL [1800 PNU]); the difference was primarily because of local reactions; there was no difference in systemic reactions (10.9% PL, 11.2% HDM-DBPC, 11.2% HDM-ALL); one out of 279 high-dose HDM allergoid-treated patients had a serious adverse event (SAE). Children (n = 39)/adolescents (n = 26) had fewer related AEs and local reactions compared to adults; systemic reactions: children 12.8%, adults 11.2% adolescents 7.7%. Females had slightly more AEs. Treatment was well tolerated in asthmatic patients (n = 267; GINA I n = 32, II n = 104, III n = 17, 114 no classification). In more than 10 years more than 100,000 patients were treated with high-dose HDM allergoid (1800 PNU) under daily practice conditions. Adverse drug reactions (ADRs) were reported in 0.5% of patients. 94.6% of these ADRs were expected. CONCLUSION: SCIT with the marketed dose of high-dose HDM allergoid was well tolerated in clinical development and in daily practice. There was no increased risk for the investigated patient subgroups. Tolerability was comparable to HDM sublingual immunotherapy (SLIT) tablets.