RT Journal Article SR Electronic T1 Response of Triple-negative Breast Cancer Liver Metastasis to Oral Recombinant Methioninase in a Patient-derived Orthotopic Xenograft (PDOX) Model JF In Vivo JO In Vivo FD International Institute of Anticancer Research SP 3163 OP 3169 DO 10.21873/invivo.12151 VO 34 IS 6 A1 HYE IN LIM A1 JUN YAMAMOTO A1 QINHONG HAN A1 YU SUN A1 HIROTO NISHINO A1 YOSHIHIKO TASHIRO A1 NORIHIKO SUGISAWA A1 YUYING TAN A1 HEE JUN CHOI A1 SEOK JIN NAM A1 MICHAEL BOUVET A1 ROBERT M. HOFFMAN YR 2020 UL http://iv.iiarjournals.org/content/34/6/3163.abstract AB Background/Aim: The aim of this study was to establish a patient-derived orthotopic xenograft (PDOX) mouse model of liver metastasis of triple-negative breast cancer (TNBC) and examine the efficacy of oral recombinant methioninase (o-rMETase) on the liver metastasis. Materials and Methods: TNBC from a patient was implanted in the left hepatic lobe of nude mice to simulate liver metastasis in a PDOX model. Ten days later, all mice underwent laparotomy to measure tumor size and were randomized to three groups: control; o-rMETase 100 U once daily (qd); and o-rMETase 200 U qd. After 9 days of treatment, all mice were sacrificed. Results: At the end of the treatment period for the liver metastasis, the size of liver metastases was 372.6 mm3 in the control group; 160.0 mm3 in the o-rMETase 100 U group; and 245.3 mm3 in the o-rMETase 200 U group. All mice had ascites and 12 out of 14 mice in all groups had mesenteric lymph-node metastasis, as re-metastasis. The mean body-condition score was 1.5 in the control group; 2.4 in the o-rMETase 100 U group; and 2.6 in the o-rMETase 200 U group (control group vs. o-rMETase 200 U group, p<0.05). Conclusion: The TNBC liver metastasis was highly aggressive resulting in re-metastasis and ascites. o-rMETase tended to inhibit the liver metastasis and significantly improved the mouse body-condition score. This new PDOX model of TNBC liver metastasis will be useful for identifying effective agents for this recalcitrant disease.