Dll4 Inhibition plus Aflibercept Markedly Reduces Ovarian Tumor Growth

Abstract

Dll4, one of the Notch ligands, is overexpressed in ovarian cancer, especially in tumors resistant to anti–VEGF therapy. Here, we examined the biological effects of dual anti-Dll4 and anti-VEGF therapy in ovarian cancer models. Using Dll4-Fc blockade and anti-Dll4 antibodies (murine REGN1035 and human REGN421), we evaluated the biological effects of Dll4 inhibition combined with aflibercept or chemotherapy in orthotopic mouse models of ovarian cancer. We also examined potential mechanisms by which dual Dll4 and VEGF targeting inhibits tumor growth using immunohistochemical staining for apoptosis and proliferation markers. Reverse phase protein arrays were used to identify potential downstream targets of Dll4 blockade. Dual targeting of VEGF and Dll4 with murine REGN1035 showed superior anti-tumor effects in ovarian cancer models compared to either monotherapy. In the A2780 model, REGN1035 (targets murine Dll4) or REGN421 (targets human Dll4) reduced tumor weights by 62% and 82%, respectively; aflibercept alone reduced tumor weights by 90%. Greater therapeutic effects were observed for Dll4 blockade (REGN1035) combined with either aflibercept or docetaxel P < 0.05 for the combination vs. aflibercept). The superior anti-tumor effects of REGN1035 and aflibercept were related to increased apoptosis in tumor cells compared to the monotherapy. We also found that GATA3 expression was significantly increased in tumor stroma from the mice treated with REGN1035 combined with docetaxel or aflibercept, suggesting an indirect effect of these combination treatments on the tumor stroma. These findings identify that dual targeting of Dll4 and VEGF is an attractive therapeutic approach.

GATA3 as a master regulator and therapeutic target in ovarian high‐grade serous carcinoma stem cells

“…Indeed, a recent report suggested that treatment with anti-Delta-like ligand 4 (DLL4, a Notch ligand), combined with docetaxel or antivascular endothelial growth factor receptor (anti-VEGFR), may upregulate GATA3 in tumors, in a mouse model of ovarian cancer. 42 However, the exact mechanism(s) by which GATA3 may be induced, in tumors, demand additional exploration.…”

Dichotomy of Notch signalling in regulating tumour immune surveillance

“…Inhibition of γ‐secretase, and that targeting nicastrin could be a novel therapeutic strategy against cancer caused by aberrant γ‐secretase activity and Notch signalling . In addition to γ ‐secretase inhibitors, monoclonal antibodies targeting DLL4 like Enoticumab (REGN421) and Demcizumab are being clinically tested in advanced ovarian, colon and breast cancer patients with overexpression of DLL4 . However, Demcizumab showed hypertension and an increased risk of congestive heart failure as side effects after prolonged drug usage …”

The role of tumor microenvironment in resistance to anti-angiogenic therapy

“…Delta-like ligand 4-NOTCH1 signaling has been demonstrated to mediate tumor resistance to anti-VEGF therapy in preclinical models by activating multiple pathways 141 . In preclinical ovarian cancer models, we have shown that dual targeting of DLL4 and VEGF exhibits superior anti-tumor effects 142 . Two humanized DLL4 antibodies—enoticumab (REGN421) and demcizumab (OMP-21M18)—have shown preliminary anti-tumor activity in ovarian cancer and other solid tumors in phase I studies 143 , 144 .…”