In line with the hypothesis that inhibition of ABCG2 could potentially improve chemotherapy efficacy, drug-resistant cells were re-sensitized to SN-38 upon SCO-101 exposure, hence providing a clinical rationale for re-sensitization to irinotecan in irinotecan-resistant patients, which is being tested in a Phase IB study in pancreatic cancer and in a Phase II clinical trial in colorectal cancer patients [34,57]. Here, ABCG2 is linked to colorectal cancer.