This disclosure relates to VIP antagonist for uses in managing the treatment or prevention of cancer and viral infections. In certain embodiments, this disclosure relates to chimeric variants of VIP antagonists, as peptides disclosed herein, and pharmaceutical composition comprising the same. In certain embodiments, this disclosure contemplates methods of stimulating immune cells to target cancer by mixing immune cells in vitro with peptides disclosed herein and further administering an effective amount of stimulated immune cells to a subject in need of cancer treatment.