Anti-DLL4 Has Broad Spectrum Activity in Pancreatic Cancer Dependent on Targeting DLL4-Notch Signaling in Both Tumor and Vasculature Cells

Abstract

Purpose: We previously showed that targeting Delta-like ligand 4 (DLL4) in colon and breast tumors inhibited tumor growth and reduced tumor initiating cell frequency. In this report, we have extended these studies to pancreatic cancer and probed the mechanism of action in tumor and stromal cells involved in antitumor efficacy.Experimental Design: Patient-derived pancreatic xenograft tumor models were used to evaluate the antitumor effect of anti-DLL4. To investigate the mechanism of action, we compared the activity of targeting DLL4 in tumor cells with an anti-human DLL4 antibody (anti-hDLL4) and in the host stroma/vasculature with an anti-mouse DLL4 antibody (anti-mDLL4). The effect of these antibodies on cancer stem cell frequency was examined by in vivo limiting dilution assays.Results: The combination of anti-hDLL4 and anti-mDLL4 was efficacious in a broad spectrum of pancreatic tumor xenografts and showed additive antitumor activity together with gemcitabine. Treatment with either anti-hDLL4 or anti-mDLL4 delayed pancreatic tumor recurrence following termination of gemcitabine treatment, and the two together produced an additive effect. Anti-hDLL4 had a pronounced effect in reducing the tumorigenicity of pancreatic cancer cells based on serial transplantation and tumorsphere assays. In contrast, disruption of tumor angiogenesis with anti-mDLL4 alone or with anti-VEGF had minimal effects on tumorigenicity. Gene expression analyses indicated that anti-DLL4 treatment regulated genes that participate in Notch signaling, pancreatic differentiation, and epithelial-to-mesenchymal transition.Conclusions: Our findings suggest a novel therapeutic approach for pancreatic cancer treatment through antagonism of DLL4/Notch signaling.

Cyclin G1 Expands Liver Tumor-Initiating Cells by Sox2 Induction via Akt/mTOR Signaling

“…3C). Moreover, hepatoma cells expressing cyclin G1 exhibit enhanced tumor initiating capacity (27) in NOD-SCID mice compared with the control cells (Table 1 and Fig. 3D).…”

Antagonism of Ang-Tie2 and Dll4-Notch signaling has opposing effects on tumor endothelial cell proliferation, evidenced by a new flow cytometry method

“…Our findings are consistent with the previous observations that inhibition of Dll4 increased TAEC number, which results in excessive angiogenic sprouting and branching with disordered tumor vascular geometry. [13][14][15][16][17] There is growing interest in combining antiangiogenic agents in an effort to enhance tumor cell starvation and to overcome issues of resistance. 36 One intriguing approach would be to simultaneously suppress both angiopoietin-Tie2 and Dll4-Notch signaling pathways; this may enhance the suppression of functional angiogenesis within the tumor microenvironment.…”

“…[7][8][9][10][11][12] In contrast, several studies have shown that administration of an anti-Dll4-specific antibody stimulates the proliferation of endothelial tip cells and increases vascular density in human tumor xenografts. [13][14][15][16][17] However, this is believed to contribute to tumor starvation and suppression of tumor growth as inhibition of Dll4-Notch signaling results in the formation of nonfunctional immature vessels leading to poor tumor perfusion.…”

Balancing Efficacy and Safety of an Anti-DLL4 Antibody through Pharmacokinetic Modulation

“…Specifically, inhibition of DLL4 signaling during angiogenesis disrupts the dynamic balance between tip and stalk cells (10), resulting in a chaotic vascular network characterized by excessive sprouting and branching, dramatically reduced vessel lumen size, and increased vascular density (11)(12)(13). DLL4 neutralizing (anti-DLL4) antibodies have been associated with robust antitumor activity in a wide range of preclinical efficacy models (14)(15)(16)(17)(18), likely by promoting nonproductive angiogenesis that impairs tumor microcirculation and induces hypoxia (19,20). In addition to the potent antitumor activity observed following anti-DLL4 treatment, additive antitumor activity has also been observed in combination with anti-VEGF therapy and/or chemotherapy (14,(16)(17)(18)21).…”

“…DLL4 neutralizing (anti-DLL4) antibodies have been associated with robust antitumor activity in a wide range of preclinical efficacy models (14)(15)(16)(17)(18), likely by promoting nonproductive angiogenesis that impairs tumor microcirculation and induces hypoxia (19,20). In addition to the potent antitumor activity observed following anti-DLL4 treatment, additive antitumor activity has also been observed in combination with anti-VEGF therapy and/or chemotherapy (14,(16)(17)(18)21). Based on the important role of DLL4 in vascular biology as well as the broad preclinical antitumor activity of anti-DLL4 monoclonal antibodies, several anti-DLL4 molecules are currently being investigated in clinical trials as potential cancer therapeutics (22).…”