Abstract 1995: Low-dose eribulin suppresses lung metastasis of osteosarcomain vitroandin vivo

Osteosarcoma is the most common malignant bone tumor among children and adolescents. The prognosis of osteosarcoma remains poor in these thirty years because the effective therapeutic option for lung metastasis has not been established. Therefore, the development of effective metastatic therapy is required. Eribulin, a new microtubule targeting agent, has been indicated for recurrent breast cancer and malignant soft tissue sarcoma. Clinical trials of eribulin showed that it elongated overall survival period rather than disease-free survival period. These results motivated us to investigate the effect of eribulin on metastasis suppression of osteosarcoma. Here, we examined the inhibitory effect of eribulin on lung metastasis and its mechanism using murine osteosarcoma metastasis model. In vivo experiments: Eribulin was intravenously injected by two administration methods, (1) high dose administration on standard schedule; 1 mg/kg q7d × 2, (2) frequent low dose administration; 0.3 mg/kg q4d × 4. Both methods sufficiently reduced circulating tumor cells in blood and inhibited lung metastasis. Method (1) also inhibited primary tumor growth, but induced severe body weight loss. Method (2) had little effect on primary tumor growth and showed little body weight loss. In vitro experiments: The IC50 concentration of eribulin for metastatic osteosarcoma cell line, LM8, was about 20 nM. Pharmacokinetics studies have shown that eribulin intravenously administered at 1 mg/kg presents with a brief high-concentration phase which surges to ≥100 nM followed by a long low-concentration phase which stabilizes at ~10 nM for one week. These two phases sandwiched the IC50 concentration of eribulin. Thus, we separately investigated that the effect of high and low eribulin concentrations on LM8. High eribulin concentrations induced cell cycle arrest and apoptosis in LM8, whereas low eribulin concentrations changed cell morphology and decreased cell migration through reducing directionality and focal adhesion turnover. Reduced peripheral localization of adenomatous polyposis coli (APC) protein by eribulin might cause these effects. In a three-dimensional collagen culture system, low eribulin concentrations inhibited tumor cell infiltration and colony formation. The anti-metastatic effects at low concentrations backed-up the results of our in vivo experiments by frequent low dose administration method. Eribulin is a potential therapeutic option for lung metastasis of osteosarcoma. Frequent low dose administration method with fewer side effects enables the combination with other chemotherapeutic agents and broadens the application of eribulin as an anti-metastatic drug for osteosarcoma. Citation Format: Kenta Watanabe, Yoshihiro Yui, Satoru Sasagawa, Kayo Suzuki, Masahiko Kanamori, Taketoshi Yasuda, Tomoatsu Kimura. Low-dose eribulin suppresses lung metastasis of osteosarcoma in vitro and in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1995.