Abstract LB-347: Ang-2/VEGF bispecific antibody reprograms macrophages and resident microglia to anti-tumor phenotype and prolongs glioblastoma survival

Abstract

OBJECTIVE: We aimed to enhance the efficacy of anti-VEGF therapy in glioblastoma (GBM) through additional inhibition of Angiopoietin-2 (Ang-2), a potential mediator of resistance to antiangiogenic therapy using VEGF inhibition. INTRODUCTION: Glioblastoma (GBM) is a uniformly lethal primary brain tumor affecting more than 12.000 patients every year in the US alone. The standard therapy regimen for this highly angiogenic tumor entity comprises maximal safe resection and chemoradiation with temozolomide. The addition of antiangiogenic (anti-VEGF) therapy to the standard of care regimen improved progression-free survival, but failed to improve overall survival of GBM patients. Preclinical and clinical data suggest that resistance to anti-VEGF therapy in GBM is mediated by Ang-2, making this pathway a potential target. EXPERIMENTAL DESIGN: We tested the effect of dual Ang-2/VEGF blockade with A2V on mouse survival using a syngeneic (Gl261) model and a human xenograft (MGG8) model, compared to anti-VEGF antibody therapy (B20). In addition, we used blood-based Gaussian Luciferase (GLUC) assays, immunohistochemistry and flow cytometry to measure changes in tumor growth, microvessel density (MVD), and immune microenvironment, respectively. RESULTS: Gl261 tumors have a highly abnormal tumor vasculature. In this model, treatment with A2V reduced MVD compared to B20. The decrease in MVD was due to a reduction in pericyte-low tumor vessels, while pericyte-high vessels were unaffected. These vascular changes were accompanied by reduced tumor burden and enhanced survival. Interestingly, in the MGG8 tumors, which have a vasculature similar to the normal brain, we detected no change in MVD after A2V treatment. Nevertheless, we found a reduced tumor burden and prolonged animal survival in the MGG8 model. Since vascular normalization may impact immune cell infiltration and function in tumors, we next evaluated these cell populations. We found that A2V therapy reduced pro-tumor M2 polarization of macrophages and microglia and reprogrammed these cells toward the M1 phenotype in both the Gl261 and MGG8 models. Collectively, our data indicate that therapy-induced anti-tumor immunity is mediated by M1-type macrophages but not by T-cell infiltration or function. CONCLUSION: Dual Ang-2/VEGF therapy with A2V reprogrammed macrophages and microglia from pro-tumor M2 toward the anti-tumor M1 phenotype in two GBM models, in addition to normalizing vasculature in tumors with abnormal vessels. These data indicate that dual anti-angiogenic therapy has the potential to overcome resistance to anti-VEGF therapy and confer clinical benefits in GBM patients through vascular and immuno-modulatory effects. Citation Format: Jonas Kloepper, Lars Riedemann, Zohreh Amoozgar, Giorgio Seano, Katharina H. Susek, Veronica Yu, Nisha Dalvie, Robin L. Amelung, Meenal Datta, Jonathan W. Song, Vasileios Askoxylakis, Jennie W. Taylor, Christine Lu-Emerson, Ana Batista, Nathaniel D. Kirkpatrick, Keehoon Jung, Matija Snuderl, Alona Muzikansky, Kay G. Stubenrauch, Oliver Krieter, Hiroaki Wakimoto, Lei Xu, Lance L. Munn, Dan G. Duda, Dai Fukumura, Tracy T. Batchelor, Rakesh K. Jain. Ang-2/VEGF bispecific antibody reprograms macrophages and resident microglia to anti-tumor phenotype and prolongs glioblastoma survival. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr LB-347.

Current landscape and future directions of bispecific antibodies in cancer immunotherapy

“…In addition to showing strong anti-tumor, antiangiogenic, and micrometastasis growth reducing effects in subcutaneous and orthotopic syngeneic mouse xenotransplantations, Ang-2-VEGF CrossMab also exhibits these effects in patient or cell linederived humanized tumor xenografts with acceptable side effects compared to Ang-1 inhibition combined with anti-VEGF treatment on physiologic vessel growth (103). Furthermore, Kloepper, Riedemann et al found that dual Ang-2/VEGF (CrossMab, A2V) antibody can prolong the survival of mice bearing orthotopic syngeneic (Gl261) GBMs or human (MGG8) GBM xenografts based on only VEGF pathway blocking failing to enhance overall survival of patients with GBM (104). The logical combination therapy of immune checkpoints and angiogenesis provides greater therapeutic effects, according to Schmittnaegel et al On the other hand, increased intratumoral immune effector cell activation results in increased PD-L1 expression in tumoral endothelial cells (105).…”

Manipulation of the crosstalk between tumor angiogenesis and immunosuppression in the tumor microenvironment: Insight into the combination therapy of anti-angiogenesis and immune checkpoint blockade

“…ABTAA favorably resulted in immune reprogramming in tumors, implying that simultaneous Tie-2 activation and Ang-2 suppression potently confer a favorable TME to facilitate the delivery of chemotherapeutic drugs into tumors (151). Furthermore, Jain and co-workers treated glioblastoma-bearing mice with antibodies targeting Ang-2/VEGF (CrossMab, A2V), and found that A2V attenuated microvascular density and polarized M2-like TAMs toward the anti-tumoral M1-like TAMs, leading to the retardation of tumor progression (152).…”

Targeting tumor‐associated macrophages: A potential treatment for solid tumors

“…Kloepper et al have found that A2V, the ANG-2/VEGF cross-monoclonal antibody, reprograms protumor M2 macrophages toward the antitumor M1 phenotype in Gl261 and MGG8 glioblastoma models. They have shown that A2V may prolong survival in mice with GBM by reprogramming TAMs (Kloepper et al, 2016;Peterson et al, 2016). (Cook et al, 2016).…”

“…Tumor-derived ANG-2 stimulates TIE2expressing monocytes/macrophages to exhibit a broader, tumor-promoting phenotype by binding to the ANG-1 receptor, a tyrosine kinase receptor(Coffelt et al, 2010).Kloepper et al have found that A2V, the ANG-2/VEGF cross-monoclonal antibody, reprograms protumor M2 macrophages toward the antitumor M1 phenotype in Gl261 and MGG8 glioblastoma models. They have shown that A2V may prolong survival in mice with GBM by reprogramming TAMs(Kloepper et al, 2016;Peterson et al, 2016).1.13 | Inhibition of HDACs HDACs serve as removing the acetyl groups on histones, a crucial step in epigenetic-regulating gene expression. HDAC family is composed of 18 proteins in mammals, which are divided into four classes (Class I, II, III, and IV).…”