Background:

SN-38 (NK012) is an active metabolite of the Topoisomerase I inhibitor Irinotecan. SN-38 (NK012) inhibits DNA and RNA synthesis with IC50s of 0.077 and 1.3 μM, respectively.

The IC50 values for LoVo, HCT116, and HT29 cell lines is 20 nM, 50 nM, 130 nM, respectively. In all three SN-38 (NK012) resistant cell lines Top1 activity is maintained in the presence of high concentrations of SN-38[2].

SN-38 (NK012), the active and toxic metabolite of the anticancer prodrug Irinotecan. At 30 minutes after administration, Irinotecan plasma concentrations in Slco1a/1b(?/?) mice are 1.9-fold higher than in the wild-type mice (1.89 vs. 1.01 μM, respectively), whereas SN-38 (NK012) plasma concentrations of Slco1a/1b(?/?) mice are 8-fold higher compare with wild-type mice (0.4 μg/mL vs. 0.05 μg/mL, respectively). Overall plasma exposure [AUC(5-240)] of Irinotecan is 1.7-fold higher in Oatp1a/1b knockout mice versus wild-type mice (209.8±6.7 vs. 120.9±4.4 μM/min; P<0.01), and 2.9-fold higher for SN-38 (50±2.9 vs. 12±2 μM/min; P<0.001)[3].

参考文献:
[1]. Wallin A, et al. Anticancer effect of SN-38 on colon cancer cell lines with different metastatic potential. Oncol Rep. 2008 Jun;19(6):1493-8.
[2]. Jensen NF, et al. Characterization of DNA topoisomerase I in three SN-38 resistant human colon cancer cell lines reveals a newpair of resistance-associated mutations. J Exp Clin Cancer Res. 2016 Mar 31;35:56.
[3]. Stewart CF, et al. Disposition of irinotecan and SN-38 following oral and intravenous irinotecan dosing in mice. Cancer Chemother Pharmacol. 1997;40(3):259-65.