Allergy is the most prevalent chronic inflammatory disease, having great socio-economic impact. Chronic lifelong dependency on symptomatic drugs is an expensive reality for the vast majority of allergy sufferers. Allergen-specific immunotherapy is the only causal and effective treatment targeting the underlying immune mechanism in a more cost-effective way. Yet, long treatment duration and risk of anaphylactic side-effects have prevented this treatment from becoming the first choice. BM4SIT aims at providing an escape from its current niche position by making the treatment safer, more effective and patient friendlier, i.e. developing a therapy with negligible side-effects but improved efficacy, achieved by less injections. The concept of BM4SIT is based on two innovations: replacing current natural allergen extracts by mutated recombinant allergens having been designed to be hypo-allergenic but hyper-immunogenic, and adding an adjuvant to support rapid and effective induction of an anti-inflammatory immune response. The allergen derivative chosen to bring this concept from bench to bedside is BM4, a mutant of the culprit allergen of birch pollen allergy, Bet v 1. Pre-clinical data have demonstrated strongly reduced allergenicity, significantly increased immunogenicity and efficacy in a mouse model for birch pollen allergy. The selected adjuvant is vitamin D3, which has been shown to promote active suppression of inflammation, both in vitro and in a mouse model. The product-focused, IP-protected consortium of BM4SIT will bring BM4 and vitamin D3 to the start of Phase III clinical trials via the stages of GMP production, toxicity studies, and Phase I and II clinical trials. Addition of vitamin D3 will first be evaluated against placebo and a current product, followed by a safety and dose-range-finding study using BM4 and vitamin D3. BM4SIT will pave the way towards a better more attractive therapy that will improve the cost-benefit ratio compared to symptomatic drugs.