Nemorubicin has antitumor activity, with IC 70 s of 578 nM, 468 nM, 193 nM, 191 nM, 68 nM, and 131 ± 9 nM for HT-29, A2780, DU145, EM-2, Jurkat and CEM cell lines, respectively. Nemorubicin is CYP3A-activated anticancer prodrug, which can produce a more cytotoxic metabolite, PNU-159682. Nemorubicin acts through nucleotide excision repair (NER) system to exert its activity. Nemorubicin (0-0.3 μM) is more active in the L1210/DDP cells with intact NER than in the XPG-deficient L1210/0 cells. Cells resistant to nemorubicin show increased sensitivity to UV damage. Nemorubicin is cytotoxic to 9L/3A4 cells, with an IC 50 of 0.2 nM, 120-fold lower than that of P450-deficient 9L cells (IC 50 , 23.9 nM). Nemorubicin also potently inhibits Adeno-3A4 infected U251 cells with IC 50 of 1.4 nM. P450 reductase overexpression enhances cytotoxicity of Nemorubicin.
Nemorubicin is converted to PNU-159682 by human liver cytochrome P450 (CYP) 3A4 in rat, mouse, and dog liver microsomes. Nemorubicin (60 µg/kg) induces sifnificant tumor growth delay in scid mice bearing 9L/3A4 tumors, but shows no obvious effect on the tumor growth delay of 9L tumors in mice by i.v. or intratumoral injection (i.t.). Nemorubicin (40 µg/kg, i.p.) exhibits no antitumor activity and no host toxicity in mice bearing 9L/3A4 tumors.