ABCB1 overexpression decreases irinotecan response rate to irinotecan-based chemotherapy by 40%, shortens PFS (HR = 1.7) and elevates hepatic metastasis risk 2.1-fold, with amplified chemoresistance and metastatic effects in CD44+/CD133+ CSCs, collectively exacerbating chemoresistance and metastatic progression in CRC [24]. This evidence concerns the gene ABCB1 and colorectal carcinoma.