FAST: towards safe and effective subcutaneous immunotherapy of persistent life-threatening food allergies

Abstract

The FAST project (Food Allergy Specific Immunotherapy) aims at the development of safe and effective treatment of food allergies, targeting prevalent, persistent and severe allergy to fish and peach. Classical allergen-specific immunotherapy (SIT), using subcutaneous injections with aqueous food extracts may be effective but has proven to be accompanied by too many anaphylactic side-effects. FAST aims to develop a safe alternative by replacing food extracts with hypoallergenic recombinant major allergens as the active ingredients of SIT. Both severe fish and peach allergy are caused by a single major allergen, parvalbumin (Cyp c 1) and lipid transfer protein (Pru p 3), respectively. Two approaches are being evaluated for achieving hypoallergenicity, i.e. site-directed mutagenesis and chemical modification. The most promising hypoallergens will be produced under GMP conditions. After pre-clinical testing (toxicology testing and efficacy in mouse models), SCIT with alum-absorbed hypoallergens will be evaluated in phase I/IIa and IIb randomized double-blind placebo-controlled (DBPC) clinical trials, with the DBPC food challenge as primary read-out. To understand the underlying immune mechanisms in depth serological and cellular immune analyses will be performed, allowing identification of novel biomarkers for monitoring treatment efficacy. FAST aims at improving the quality of life of food allergic patients by providing a safe and effective treatment that will significantly lower their threshold for fish or peach intake, thereby decreasing their anxiety and dependence on rescue medication.

Figure 1

Four different (hypo-)allergenic constructs are proposed in developing a construct for fish SIT. A/B: n/r wild-type Cyp c 1 and the Calcium-binding site double mutant as described before [26,27], C: glutaraldehyde treated rCyp c 1 (involves covalent linking of free amino-groups, as shown).

Figure 2

Seven different (hypo-)allergenic constructs are proposed in developing a construct for peach SIT. wt and rPru p 3 (sequence shown), a "natural hypoallergenic" rFra a 3 (changes in sequence compared to Pru p 3 are underlined), rPru p 3 sur: a surface mutant (3 amino acids mutated to Alanin), rPru p 3 cys: 4 cysteines mutated to serine, rPru p 3 G: glutaraldehyde treated rPru p 3 (involves free amino-groups, indicated), rPru p 3 RA: reduced and alkylated rPru p 3 (involves all cysteines). The known IgE-binding sites of Pru p 3 are boxed, H1-4 indicate the α-helices.