A Single Low Dose of Eribulin Regressed a Highly Aggressive Triple-negative Breast Cancer in a Patient-derived Orthotopic Xenograft Model.

Background/Aim: In the present study, the breast cancer patient-derived orthotopic xenograft (PDOX) model was used to identify an effective drug for a highly aggressive triple negative breast cancer (TNBC). Materials and Methods: The TNBC tumor from a patient was implanted in the right 4th inguinal mammary fat pad of nude mice to establish a PDOX model. Three weeks later, 19 mice were randomized into the untreated-control group (n=10) and the eribulin treatment group (n=9, eribulin, 0.3 mg/kg, i.p., day 1). Results: On day 8, eribulin significantly inhibited tumor volume compared to the control group (p<0.01). Eribulin regressed tumors in 3 mice (33.3%) and apparently eradicated them in 6 mice (66.7%). At day 14, tumor regrowth was observed in 2 mice of the eribulin group, which was undetectable on day 8. However, 44.4% (4 out of 9) of the mice in the eribulin group were tumor-free on day 14. Conclusion: A single low-dose eribulin was efficacious on a highly aggressive TNBC. The breast cancer PDOX model can be used to identify highly effective drugs for TNBC.