Fig. 5. IRE1α kinase inhibition impairs growth of subcutaneous and orthotopic human TNBC tumor xenografts in mice and cooperates with anti-VEGF-A antibody therapy to cause tumor regression.

(A-C) MDA-MB-231 (A) or HCC1806 cells (B) were inoculated subcutaneously into female C.B-17 SCID (A) or SCID.bg mice (B), or HCI-004 tumor fragments were surgically transplanted into the mammary fat pad of female NOD SCID mice (C) and allowed to establish tumors of ~150 mm³. Mice were then randomized into the following groups (n=15/ group in A and C, n=20/ group in B): (i) vehicle; (ii) anti-VEGF-A (2 mg/kg) intraperitoneally (IP) twice per week (BIW); (iii) compound 18 (30 mg/kg) IP once per day (QD); or (iv) combination of compound 18 and anti-VEGF-A. Tumor growth was monitored for the indicated time. Individual tumor data are shown in Supplementary Fig. S5A (for A), Supplementary Fig. S5D (for B) and Supplementary Fig. S5I (for C). (D) Expression of Cox-2 (PTGS2), CXCL8, and CXCR4 in HCC1806 parental or IRE1α KO subcutaneous tumor xenografts treated with or without anti-VEGF-A for 7 days was analyzed by RNA-seq. (E and F) Flow cytometric analysis quantifying Pdpn-positive and Pdgfrα-positive CAFs in subcutaneous MDA-MB-231 (E) or HCC1806 (F) tumor xenografts treated with Compound 18, anti-VEGF-A, or the combination of both as outlined above. (G) FAP staining analysis of subcutaneous MDA-MB-231 parental or IRE1α KO tumor xenografts. Right: representative images. In vivo data depict mean tumor volume ± SEM. *p<0.05, **p≤0.01, ***p≤0.001.