TACSTD2 and neoplasm: It is important to note that mice administered irinotecan received 37.5-fold more SN-38 than those treated with SG (2.4 mg vs. 0.064 mg total SN-38 equivalents, respectively), suggesting that the improved efficacy observed in the C13 and C39 tumor-bearing mice was likely due to increased SN-38 targeting and uptake mediated by SG due to higher Trop-2 expression and not to any gained sensitivity to SN-38 itself.