The combination of 30 mg/kg oral VKNG-1 with a dose of 10 mg/kg i.p. of irinotecan significantly reduced tumor size, growth rate, and tumor volume in mice with ABCG2-overexpressing tumor xenografts, compared to either drug alone in ABCG2-overexpressing colon cancers. This evidence concerns the gene ABCG2 and colonic neoplasm.