Eisai Co., Ltd. (Headquarters: Tokyo, CEO: Haruo Naito, “Eisai”) announced today that it has presented the latest research data regarding a mechanism of action that led to increased anti-tumor activity in mouse models which had been dosed with a combination of the in-house developed anticancer agent lenvatinib mesylate (lenvatinib) and an anti-mouse PD-1 antibody, at the American Association for Cancer Research (AACR) 108th Annual Meeting.

The results presented at the AACR meeting showed that when syngeneic model mice inoculated with mouse liver cancer, melanoma or colon cancer cell lines were dosed with a combination of lenvatinib (10 mg/kg, once daily) and an anti-mouse PD-1 antibody (500 g/mouse, twice a week), lenvatinib alone or an anti-mouse PD-1 antibody alone, a substantial inhibitory effect on tumor growth was observed in mice that had been dosed with the combination therapy compared to the single treatments.
Additionally, an increased number of mice in the combination therapy group showed Complete Response (CR) of tumor compared to the single treatment group. Specifically, in the combination therapy group, 7 out of 30 mice showed CR (colon cancer models: 2/10, melanoma models: 2/10, liver cancer models: 3/10), whereas in each single treatment group, 1 out of 30 mice showed CR (colon cancer models: 1/10, melanoma models: 0/10, liver cancer models: 0/10).

Furthermore, in the liver cancer mouse model, even when identical cancer cell lines were re-inoculated into mice with complete tumor remission, no?in vivo?growth was observed.

RNA analysis of the cancer tissue and other tests confirmed a reduction in immunosuppressive tumor associated macrophages, a reduction in immunosuppressive signal receptors, and an increase in the ratio of memory T cells in model mice dosed with lenvatinib.

This non-clinical research suggested synergistic anti-tumor activity when combining lenvatinib with an anti-mouse PD-1 antibody in the mouse models, based on an immunostimulatory response due to the reduction in tumor associated macrophages and the enhancement of the ratio of memory T cells by lenvatnib.

Eisai has positioned oncology as a key therapeutic area of focus and remains committed to providing further evidence for lenvatinib as it seeks to contribute further to addressing the diverse needs of, and increasing the benefits provided to, patients with cancer, their families, and healthcare providers.