Fig. 5. Birinapant sensitizes TNBC PDX tumors to conventional therapy in vivo.

a Cell death assessed by measurement of PI positive cells by flow cytometry of MDA-MD-231 cells treated with either 5 nM of docetaxel for 48 h or 250 nM of birinapant for 24 h or pretreated 24 h with 5 nM of docetaxel and then treated 24 h with 250 nM birinapant (doce + bir). Data are means ± SEM; n = 3 independent experiments. b Tumor volume curves (top panels) and Kaplan–Meier survival curves (bottom panels) for TNBC PDX-838 (n = 6–9 mice per arm). Mice were treated with vehicle alone (black line) or 15 mg/kg of birinapant alone (green line, intraperitoneally three times/week for seven weeks) or with 10 mg/kg docetaxel alone (blue line, intraperitoneally on days 1 and 22) or with combined docetaxel and birinapant (red line). Mice were sacrificed when tumor size reached the experimental ethical end point (>600 mm³). For tumor volume curves, means ± SEM are shown. c Immunostaining for cleaved caspase-3 (CC3) and Ki67 of PDX-838 tumors treated in vivo with vehicle or with 15 mg/kg of birinapant or with 10 mg/kg docetaxel or with combined docetaxel and birinapant for 24 h. Scale bar, 50 μm. d Western blot analysis of cIAP1 and cleaved caspase-3 protein expression in lysates from PDX 838 tumors treated in vivo with vehicle or with 15 mg/kg of birinapant or with 10 mg/kg docetaxel or with combined docetaxel and birinapant for 24 h (two independent tumors per treatment). e Tumor weights from PDX 838 tumors treated in vivo with vehicle or with 15 mg/kg of birinapant or with 10 mg/kg docetaxel or with combined docetaxel and birinapant for 24 h (left panel). Level of TNF measured by ELISA in lysate from PDX-838 tumors treated in vivo with vehicle or 15 mg/kg of birinapant or with 10mg/kg docetaxel or with combined docetaxel and birinapant for 24 h (right panel). Data are means ± SD; n = 4–6 independent tumors. Each dot represents an independent tumor.