Katsuji Nakamura

Lenvatinib, an angiogenesis inhibitor targeting VEGFR/FGFR, shows broad antitumor activity in human tumor xenograft models associated with microvessel density and pericyte coverage

BackgroundLenvatinib is an oral inhibitor of multiple receptor tyrosine kinases (RTKs) targeting vascular endothelial growth factor receptor (VEGFR1-3), fibroblast growth factor receptor (FGFR1-4), platelet growth factor receptor α (PDGFR α), RET and KIT. Antiangiogenesis activity of lenvatinib in VEGF- and FGF-driven angiogenesis models in both in vitro and in vivo was determined. Roles of tumor vasculature (microvessel density (MVD) and pericyte coverage) as biomarkers for lenvatinib were also examined in this study.MethodWe evaluated antiangiogenesis activity of lenvatinib against VEGF- and FGF-driven proliferation and tube formation of HUVECs in vitro. Effects of lenvatinib on in vivo angiogenesis, which was enhanced by overexpressed VEGF or FGF in human pancreatic cancer KP-1 cells, were examined in the mouse dorsal air sac assay. We determined antitumor activity of lenvatinib in a broad panel of human tumor xenograft models to test if vascular score, which consisted of high MVD and low pericyte coverage, was associated with sensitivity to lenvatinib treatment. Vascular score was also analyzed using human tumor specimens with 18 different types of human primary tumors.ResultLenvatinib inhibited VEGF- and FGF-driven proliferation and tube formation of HUVECs in vitro. In vivo angiogenesis induced by overexpressed VEGF (KP-1/VEGF transfectants) or FGF (KP-1/FGF transfectants) was significantly suppressed with oral treatments of lenvatinib. Lenvatinib showed significant antitumor activity in KP-1/VEGF and five 5 of 7 different types of human tumor xenograft models at between 1 to 100 mg/kg. We divided 19 human tumor xenograft models into lenvatinib-sensitive (tumor-shrinkage) and relatively resistant (slow-growth) subgroups based on sensitivity to lenvatinib treatments at 100 mg/kg. IHC analysis showed that vascular score was significantly higher in sensitive subgroup than relatively resistant subgroup (p < 0.0004). Among 18 types of human primary tumors, kidney cancer had the highest MVD, while liver cancer had the lowest pericyte coverage, and cancers in Kidney and Stomach had highest vascular score.ConclusionThese results indicated that Lenvatinib inhibited VEGF- and FGF-driven angiogenesis and showed a broad spectrum of antitumor activity with a wide therapeutic window. MVD and pericyte-coverage of tumor vasculature might be biomarkers and suggest cases that would respond for lenvatinib therapy.

A novel carbazole topoisomerase II poison, ER-37328: potent tumoricidal activity against human solid tumors in vitro and in vivo

We have discovered a novel topoisomerase II (topo II) poison, ER‐37328 (12,13‐dihydro‐5‐[2‐(dimethylamino)ethyl]‐4H‐benzo[c]py‐rimido[5,6,1‐jk]carbazole‐4,6,10(5H, 11H)‐trione hydrochloride), which shows potent tumor regression activity against Colon 38 cancer inoculated s.c. Here, we describe studies on the cell‐killing activity against a panel of human cancer cell lines and the antitumor activity of ER‐37328 against human tumor xenografts. In a cell‐killing assay involving 1‐h drug treatment, ER‐37328 showed more potent cell‐killing activity (50% lethal concentrations (LC50s) ranging from 2.9 to 20 μM) than etoposide (LC50s>60 μM) against a panel of human cancer cell lines. ER‐37328 induced double‐stranded DNA cleavage, an indicator of topo II‐DNA cleavable complex formation, within 1 h in MX‐1 cells, and the extent of cleavage showed a bell‐shaped relationship to drug concentration, with the maximum at 2.5 μM. After removal of the drug (2.5 μM) at 1 h, incubation was continued in drug‐free medium, and the amount of cleaved DNA decreased. However, at 10 μM, which is close to the LC50 against MX‐1 cells, DNA cleavage was not detected immediately after 1‐h treatment, but appeared and increased after drug removal. This result may explain the potent cell‐killing activity of ER37328 in the 1‐h treatment. In vivo, ER‐37328 showed potent tumor regression activity against MX‐1 and NS‐3 tumors. Moreover, ER‐37328 had a different antitumor spectrum from irinotecan or cisplatin against human tumor xenografts. In conclusion, ER‐37328 is a promising topo II poison with strong cell killing activity in vitro and tumor regression activity in vivo, and is a candidate for the clinical treatment of malignant solid tumors. (Cancer Sci 2003; 94: 119–124)

Antitumor activity of ER-51785, a new peptidomimetic inhibitor of farnesyl transferase: synergistic effect in combination with paclitaxel.

Inhibitors of ras farnesylation have been extensively studied in the preclinical stage, and some of them are being developed in the clinic. Herein, we describe the antitumor activity of a new farnesyl transferase inhibitor, ER-51785. In vitro, ER-51785 selectively inhibited farnesyl transferase activity (IC50 = 77 nM) compared with geranylgeranyl transferase I activity (IC50 = 4200 nM). In cells, ER-51785 inhibited posttranslational processing of H-ras with IC50 = 28 nM, but not that of rap 1A at concentrations up to 50 microM. This compound also strongly inhibited colony formation of H-ras-transformed NIH 3T3 fibroblasts and EJ-1 bladder carcinoma cells. In vivo, ER-51785 showed potent tumor regression activity against EJ-1 xenografts but only modest activity against MIA PaCa-2 xenografts. Treatment of ER-51785 in combination with paclitaxel exhibited synergistic effects against colony formation and tumor growth of MIA PaCa-2 cells. The results presented herein support the idea that farnesyl transferase inhibitors alone and in combination with other chemotherapeutic agents have the potential to be developed as therapies for tumors expressing H-ras or K-ras oncogenes.