With 10 million lives claimed each year, cancer remains among the leading causes of mortality worldwide—a stark reminder of the urgent need for new treatments. One promising strategy is cancer immunotherapy vaccines using mRNA encapsulated in lipid carriers, facilitating mRNA transport into target cells. However, the mRNA delivery into the cytosol remains challenging due to limited endosomal escape. To enhance the escape, we propose to computationally design proteins that induce fusion between lipid vesicles and endosomes. Using mesoscopic computer simulations, we will identify key protein features required for membrane fusion. Using these insights and both coarse-grained and all-atom models, we will design protein sequences capable of inducing fusion. In parallel, we will experimentally test the effectiveness of the designed proteins in promoting vesicle fusion and cytosolic delivery using fluorescence measurements. Functionalizing lipid vesicles with fusogenic proteins has the potential to significantly improve the delivery of degradation-prone therapeutics, such as RNA.