The invention features a compound including a mutant KRAS sequence and a lipid, where the mutant KRAS sequence is conjugated to the lipid by a linker, and (i) the linker includes one or more polyethylene glycol blocks, (ii) the lipid is 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE), and (iii) the mutant KRAS sequence comprises or consists of the amino acid sequence selected from the group consisting of SEQ ID NOs:1-7 and 22-30. The invention features a composition including one or more compounds of the invention and a pharmaceutically acceptable carrier. The invention also features a method of treating a cancer in a human patient, the method including administering the composition to the patient. Further, the invention features a kit comprising the compound.