Efficacy and Safety/Tolerability of Ragweed MATA MPL

Ragweed MATAMPL has been developed by Allergy Therapeutics to provide pre-seasonal specific immunotherapy for patients with proven type I hypersensitivity to cross reacting ragweed pollens causing rhinitis and/or conjunctivitis with or without mild to moderate asthma bronchiale. An earlier formulation of Ragweed MATAMPL developed by Allergy Therapeutics (UK), Ltd, available commercially in Canada since the 1980's, is 'Pollinex®-R'. 'Pollinex®-R' is formulated with modified allergens (allergoids) of ragweed pollen extract adsorbed onto L tyrosine at 4% w/v. Related formulations developed by ATL, available commercially in selected European countries since the 1970´s on a Named Patient Basis, are 'Pollinex Tree', 'Pollinex Grass', 'Pollinex Quattro Trees' (previously known as MATA tree + MPL), and 'Pollinex Quattro Grass' (previously known as MATA grass + MPL). Ragweed MATAMPL contains an extract of ragweed pollens. This extract is chemically modified with glutaraldehyde to produce the active ingredient, an allergoid. Such modification reduces the reactivity of the extract with IgE antibody. However, a simultaneous reduction in other important immunological properties, such as IgG and T cell reactivity is not seen. The modified extract is adsorbed to L-tyrosine as a depot formulation. MPL®, a purified, detoxified glycolipid derived from the cell walls of Salmonella minnesota, is also included in the current product formulation. This excipient/adjuvant is included to increase the immunogenic effect of the product and to enhance the switch from an allergen-specific TH2 to TH1-like T cell profile. The current formulation is designed to provide a product that will be efficacious with only 4 injections, in contrast to the longer schedules currently in use with unmodified extracts. The product will also be safer to use than a formulation containing a similar mass of unmodified allergen extract as regards its ability to cause severe local allergic reactions or anaphylaxis, because of its reduced reactivity with IgE antibody. The modification is greater than 75%, so that only a small amount of unmodified allergen is remaining in the product. The purpose of this study is to compare the efficacy of Ragweed MATAMPL versus placebo in ragweed-allergic subjects following 4 subcutaneous injections of study medication administered before the start of the 2007 ragweed pollen season.