Extra-intestinal pathogenic E. coli (ExPEC) is the most common gram-negative pathogen in humans, and can cause various infections outside of the gastrointestinal tract, which can lead to diverse and serious diseases, resulting in significant morbidity and mortality. Increasing multidrug resistance among ExPEC strains is an obstacle to treatment and leads to increasing numbers of hospitalizations and deaths and increasing healthcare costs associated with ExPEC infections.
A vaccine against ExPEC is therefore urgently needed. The O-antigen, a component of the surface lipopolysaccharide, has been identified as a promising vaccine target, and is used as antigen in a glycoconjugate vaccine that is currently under development (see, e.g. Poolman and Wacker, 2016, J. Infect. Dis. 213: 6-13).
The glycoconjugate vaccines against ExPEC that are currently under development comprise O-glycans of different serotypes of ExPEC, each coupled to a carrier protein, such as exoprotein A of Pseudomonas aeruginosa (EPA) (see e.g., WO2015/124769, and WO 2017/035181). Such a vaccine comprising O-glycans of the E. coli serotypes O25B, O1A, O2 and O6A is for instance in an ongoing phase 2 trial (ClinicalTrials.gov Identifier: NCT02546960).
It was found by the instant inventors that while the existing ExPEC vaccine formulation (25 mM Tris pH 7.4, 2.7 mM KCl, 137 mM NaCl) is acceptable for short-term storage at 2-8° C. and in-use stability, it is not robust upon freeze/thaw and under agitation stress. Accidental freezing, accidental heating, and agitation (e.g., during storage or transportation) has a detrimental impact on product integrity of the ExPEC formulations. For pharmaceutical products that are intended for use in large populations, such as a glycoconjugate vaccine against ExPEC, it is beneficial to have a formulation that can be frozen in bulk at low temperatures, and after thawing can be stored at about 2-8° C. before usage (i.e., where the drug substance is frozen for large scale and long term storage, but the drug product that is being used is stored at about 2-8° C., so at least one freeze-thaw cycle is inevitable for the product). Further, the formulation would preferably also be compatible with different materials, such that the product (e.g., the glycoconjugate) can be stored in different formats (e.g., bags, bottles, vials, prefilled syringes, and/or applicable devices).
There is a need in the art for formulations of vaccines against ExPEC, that can withstand multiple environmental stresses (e.g., freeze/thaw, agitation, elevated temperature, light exposure, metal oxidant exposure, etc.) and result in a longer stability and longer shelf life of the compositions, and preferably are compatible with multiple processing (e.g. container) materials. Any of the degradation routes resulting from an environmental stress can lead to lowered biological activity, and can potentially also result in the formation of by-products or derivatives of the components of the formulations, thus resulting in increased toxicity and/or altered immunogenicity of the ExPEC vaccine. Therefore, a tailored approach is needed to find a robust formulation for glycoconjugate vaccines ensuring stability over a wide range of conditions. Buffer type, pH, and specialized excipients will need to be selected, specifically combined, and subsequently meticulously optimized to keep glycoconjugate vaccines chemically, physically, and biologically stable. In view of all the factors that can vary, finding optimal conditions for formulating glycoconjugate vaccines against ExPEC is burdened with challenges, and the composition of a good formulation is a priori unpredictable.
Accordingly, there is a need in the art for formulations of glycoconjugate vaccines against ExPEC that ensure that the vaccine compositions can withstand multiple environmental stresses and have an improved stability and longer shelf life. It is the aim of the present invention to provide such formulations.