The evidence for commercial house dust mite immunotherapy products: a pragmatic systematic review with narrative synthesis

House dust mite (HDM) allergen immunotherapy (AIT) has an established role in the treatment of perennial allergic rhinitis (AR) and allergic asthma (AA) triggered by HDM sensitization. We aimed to identify all double-blind, randomized, placebo-controlled trial (DBRPCTs) of HDM AIT for the treatment of AR and AA in humans and to summarize the evidence for AIT products that are currently manufactured and available for clinical use. Fifty-six eligible DBRPCTs of HDM AIT for the treatment of AA and/or AR in humans fit the inclusion criteria and investigated a total of 14 commercial AIT products which enrolled a total of 14,619 patients. 39 studies investigated the current manufacturer-recommended maintenance dose (MRMD) of the product, and 17 investigated other doses. We identified 39 studies (12,539 patients randomized) for eight sublingual immunotherapy (SLIT) products and 17 studies (2080 patients randomized) for subcutaneous immunotherapy (SCIT) products. For AR, three products, the ALK 12 SQ-HDM SLIT tablet, the ALK 6 SQ-HDM tablet and the SG 300 IR SLIT tablet, had both dose-finding studies (DFS) and phase III definitive studies (DS) to demonstrate efficacy of the MRMD of the product. For AA, two products, the ALK 12 SQ-HDM SLIT tablet and ALK 6 SQ-HDM tablet, had both DFS and DS for the MRMD. No SCIT product had a paired DFS and DS that supported the MRMD. Thirty studies of products no longer commercially manufactured were excluded. This study will help to inform clinical care and product selection for the treatment of HDM-induced AR and AA.