Multitargeting Strategy Using Tetrathiomolybdate and Lenvatinib: Maximizing Antiangiogenesis Activity in a Preclinical Liver Cancer Model

Purpose: The study aims to investigate the suppressing tumor-promoting effects via multi-anti-angiogenesis activity of the copper chelator (ammonium tetrathiomolybdate, TM) combined with lenvatinib for hepatocellular carcinoma. Methods: A total of 55 C57 mice were injected subcutaneously with Hepa1-6 hepatoma cell suspensions into the right posterior thigh. After 7 days, the subcutaneous tumors were formed, and the mice were randomly divided into five groups: TM (G1), Lenvatinib (G2), TM+Lenvatinib (G3), Control (G4), and Copper (II) Gluconate (G5). The copper concentrations in serum and tumors were measured at the predetermined time points. After 14 days of treatments, tumor weight and volumes were analyzed, histology was observed, and the expressions of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in tumor tissues were measured by immunohistochemistry. Results: The median concentration of copper in serum was 401.70, 469.40, and 665.35 μg/L in normal mice, in mice 7 days after implantation, and in the control group, respectively. The intratumoral copper concentrations were higher in G4 mice than in mice 7 days after implantation (P < 0.05). The serum concentration of copper was higher in G5 than all the other groups (P < 0.05; (G1, G2, and G3) vs. G4, P < 0.05; G1 vs. G2, P = 0.013; G2 vs. G3, P = 0.018; G1 vs. G3, P = 0.903. The intratumoral copper concentrations were 608.40, 980.00, 539.31, and 2938.90 μg/L in G1, G2, G3, and G5, respectively. The average tumor weight was 0.55, 0.44, 0.08, 1.37, and 3.11 in G1, G2, G3, G4, and G5, respectively. G5 vs. other groups, P < 0.05; (G1, G2, and G3) vs. G4, P < 0.05; G1 vs. G3, P < 0.05; G2 vs. G3, P < 0.05; G1 vs. G2, P > 0.05. Furthermore, the expression levels of VEGF were significantly lower in G1, G2, and G3 than in G4 and G5 (P < 0.05). A similar trend was observed for MVD in the five groups, but no significant difference was detected in G1 and G2. Conclusion: The study showed a significant positive correlation between tumor load and copper. Copper promotes tumor progression, but copper chelating suppresses tumor growth. The combination of TM with lenvatinib reduces tumor angiogenesis and improves the effect of antitumor treatment.These findings underlie the clinical application of combination therapy.