Two companion papers from Massachusetts General Hospital (MGH) research teams suggest that targeting multiple angiogenesis pathways simultaneously could help overcome the resistance to anti-angiogenic treatment inevitably developed by the devastating brain tumor glioblastoma. Appearing in PNAS Early Edition, the reports describe how two different methods of inhibiting both vascular endothelial growth factor (VEGF) and angiopoietin-2 (Ang-2) in animal models not only normalized tumor blood vessels to a greater extent than anti-VEGF therapy alone but also shifted the action of tumor-infiltrating immune cells from a pro-tumor to an anti-tumor state.

“These papers offer a potential solution for glioblastoma’s escape from anti-VEGF therapy, which is mediated by activating alternative growth factor pathways,” says Rakesh K. Jain, PhD, director of the Steele Laboratory of Tumor Biology in the MGH Radiation Oncology Department and co-corresponding author of both papers. “In our back-to-back papers we not only provide proof-of-principle data that dual treatment strategies can slow glioblastoma growth and improve survival but also reveal the underlying mechanisms for these benefits.”

The most common malignant tumor arising in the brain, glioblastoma is characterized by a highly abnormal, leaky and inefficient blood supply, caused by the overexpression of angiogenic factors like VEGF. These vascular abnormalities lead to swelling around the tumor and poor blood perfusion within the tumor, causing it to become more aggressive and resistant to chemotherapy and radiation treatment. While anti-VEGF treatment has become part of standard postsurgical treatment for glioblastoma, its beneficial effects are temporary and do not extend patient survival.

Previous studies from members of these MGH teams revealed that glioblastoma patients receiving anti-VEGF treatment also had a transient drop in blood levels of Ang-2. Levels of that factor rebounded as tumor progression resumed, suggesting that Ang-2 activity may contribute to resistance to anti-VEGF treatment. The researchers also found that, similar to VEGF, Ang-2 is expressed by all types of glioblastomas. To capture the diversity of different glioblastoma types, the investigators designed two methods of testing whether inhibiting both pathways could overcome treatment resistance.

One approach combined the use of the experimental oral anti-VEGF drug cediranib with an Ang-2-neutralizing antibody in two mouse models of glioblastoma and found that dual therapy improved blood vessel normalization and extended survival compared with cediranib treatment alone. Dual therapy also attracted tumor-associated macrophages (TAMs) to the tumors and increased the proportion of the anti-tumor form of those immune cells. Importantly, blocking the migration of TAMs to tumors reduced the benefits of dual therapy.

The second study used an antibody that targets both VEGF and Ang-2 and showed that dual treatment improved the architecture of tumor vessels in a mouse model with abnormal vessels. TAMs were reprogrammed to an anti-tumor state in both this tumor model and in another model not characterized by abnormal vasculature, indicating that vascular normalization was not the only mechanism of benefit. In fact, dual therapy promoted anti-tumor immunity by shifting the population of TAMs towards an anti-tumor form, consistent with the first study but regardless of whether or not surrounding blood vessels were abnormal.

“Our studies indicate that dual targeting of VEGF and Ang-2 could overcome some of the shortcomings of currently available glioblastoma therapies,” says Jain, who is the Andrew Werk Cook Professor of Tumor Biology at Harvard Medical School. “Clinically accessible agents are currently available for this dual targeting strategy, and our finding that dual therapy can also improve anti-tumor immune responses, irrespective of its effect on blood vessels, is particularly timely given the rapid development of new immunotherapies. These results open new avenues of research on novel combinations to obtain more durable results against this devastating disease.”

About this brain cancer research

The co-lead authors of the study combining cediranib with an Ang-2 antibody are Teresa Peterson, Nathaniel Kirkpatrick and Yuhui Huang, all of the Steele Labs at MGH; and Dai Fukumura, MD, PhD, of the Steele Labs is co-corresponding author. Co-lead author of the study using the VEGF/Ang-2 antibody are Jonas Kloepper, Lars Riedemann, and Zohreh Amoozgar, of the Steele Labs; and Tracy Batchelor, MD, MGH Departments of Neurology and Radiation Oncology, is co-corresponding author.

Funding: Support for the studies includes National Cancer Institute grants P01-CA080124 and P50-CA165962 and grants from MedImmune, Roche and the National Foundation for Cancer Research.

Source: Katie Marquedant – Mass General

Image Credit: The image is in the public domain.

Original Research: Full open access research for “Dual inhibition of Ang-2 and VEGF receptors normalizes tumor vasculature and prolongs survival in glioblastoma by altering macrophages” by Teresa E. Peterson, Nathaniel D. Kirkpatrick, Yuhui Huang, Christian T. Farrar, Koen A. Marijt, Jonas Kloepper, Meenal Datta, Zohreh Amoozgar, Giorgio Seano, Keehoon Jung, Walid S. Kamoun, Trupti Vardam, Matija Snuderl, Jermaine Goveia, Sampurna Chatterjee, Ana Batista, Alona Muzikansky, Ching Ching Leow, Lei Xu, Tracy T. Batchelor, Dan G. Duda, Dai Fukumura, and Rakesh K. Jain in PNAS. Published online April 4 2016 doi:10.1073/pnas.1525349113

Full open access research for “Ang-2/VEGF bispecific antibody reprograms macrophages and resident microglia to anti-tumor phenotype and prolongs glioblastoma survival” by Jonas Kloepper, Lars Riedemann, Zohreh Amoozgar, Giorgio Seano, Katharina 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, and Rakesh K. Jain in PNAS. Published online April 4 2016 doi:10.1073/pnas.1525360113

Abstract

Dual inhibition of Ang-2 and VEGF receptors normalizes tumor vasculature and prolongs survival in glioblastoma by altering macrophages

Glioblastomas (GBMs) rapidly become refractory to anti-VEGF therapies. We previously demonstrated that ectopic overexpression of angiopoietin-2 (Ang-2) compromises the benefits of anti-VEGF receptor (VEGFR) treatment in murine GBM models and that circulating Ang-2 levels in GBM patients rebound after an initial decrease following cediranib (a pan-VEGFR tyrosine kinase inhibitor) administration. Here we tested whether dual inhibition of VEGFR/Ang-2 could improve survival in two orthotopic models of GBM, Gl261 and U87. Dual therapy using cediranib and MEDI3617 (an anti–Ang-2–neutralizing antibody) improved survival over each therapy alone by delaying Gl261 growth and increasing U87 necrosis, effectively reducing viable tumor burden. Consistent with their vascular-modulating function, the dual therapies enhanced morphological normalization of vessels. Dual therapy also led to changes in tumor-associated macrophages (TAMs). Inhibition of TAM recruitment using an anti–colony-stimulating factor-1 antibody compromised the survival benefit of dual therapy. Thus, dual inhibition of VEGFR/Ang-2 prolongs survival in preclinical GBM models by reducing tumor burden, improving normalization, and altering TAMs. This approach may represent a potential therapeutic strategy to overcome the limitations of anti-VEGFR monotherapy in GBM patients by integrating the complementary effects of anti-Ang2 treatment on vessels and immune cells.

“Dual inhibition of Ang-2 and VEGF receptors normalizes tumor vasculature and prolongs survival in glioblastoma by altering macrophages” by Teresa E. Peterson, Nathaniel D. Kirkpatrick, Yuhui Huang, Christian T. Farrar, Koen A. Marijt, Jonas Kloepper, Meenal Datta, Zohreh Amoozgar, Giorgio Seano, Keehoon Jung, Walid S. Kamoun, Trupti Vardam, Matija Snuderl, Jermaine Goveia, Sampurna Chatterjee, Ana Batista, Alona Muzikansky, Ching Ching Leow, Lei Xu, Tracy T. Batchelor, Dan G. Duda, Dai Fukumura, and Rakesh K. Jain in Developmental Science. Published online April 4 2016 doi:10.1073/pnas.1525349113

Abstract

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

nhibition of the vascular endothelial growth factor (VEGF) pathway has failed to improve overall survival of patients with glioblastoma (GBM). We previously showed that angiopoietin-2 (Ang-2) overexpression compromised the benefit from anti-VEGF therapy in a preclinical GBM model. Here we investigated whether dual Ang-2/VEGF inhibition could overcome resistance to anti-VEGF treatment. We treated mice bearing orthotopic syngeneic (Gl261) GBMs or human (MGG8) GBM xenografts with antibodies inhibiting VEGF (B20), or Ang-2/VEGF (CrossMab, A2V). We examined the effects of treatment on the tumor vasculature, immune cell populations, tumor growth, and survival in both the Gl261 and MGG8 tumor models. We found that in the Gl261 model, which displays a highly abnormal tumor vasculature, A2V decreased vessel density, delayed tumor growth, and prolonged survival compared with B20. In the MGG8 model, which displays a low degree of vessel abnormality, A2V induced no significant changes in the tumor vasculature but still prolonged survival. In both the Gl261 and MGG8 models A2V reprogrammed protumor M2 macrophages toward the antitumor M1 phenotype. Our findings indicate that A2V may prolong survival in mice with GBM by reprogramming the tumor immune microenvironment and delaying tumor growth.

“Ang-2/VEGF bispecific antibody reprograms macrophages and resident microglia to anti-tumor phenotype and prolongs glioblastoma survival” by Jonas Kloepper, Lars Riedemann, Zohreh Amoozgar, Giorgio Seano, Katharina 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, and Rakesh K. Jain in PNAS. Published online April 4 2016 doi:10.1073/pnas.1525360113

Feel free to share this neuroscience news.