1
|
Thomas JM, Thorpe PE. Protective Effect of Anti-Phosphatidylserine Antibody in a Guinea Pig Model of Advanced Hemorrhagic Arenavirus Infection. Open Microbiol J 2017; 11:303-315. [PMID: 29290843 PMCID: PMC5737030 DOI: 10.2174/1874285801711010303] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/01/2017] [Accepted: 11/11/2017] [Indexed: 11/22/2022] Open
Abstract
Objective Host derived markers on virally infected cells or virions may provide targets for the generation of antiviral agents. Recently, we identified phosphatidylserine (PS) as a host marker of virions and virally-infected cells. Methods and Materials Under normal physiological conditions, PS is maintained on the inner leaflet of the plasma membrane facing the cytosol. Following viral infection, activation or pre-apoptotic changes cause PS to become externalized. We have previously shown that bavituximab, a chimeric human-mouse antibody that binds PS complexed with β2-glycoprotein I (β2GP1), protected rodents against lethal Pichinde virus and cytomegalovirus infections. Results Here, we determined the antiviral activity of a fully human monoclonal antibody, PGN632, that directly binds to PS. Treatment with PGN632 protected 20% of guinea pigs with advanced infections of the hemorrhagic arenavirus, Pichinde, from death. Combining PGN632 with ribavirin improved the antiviral activity of both agents, such that the combination rescued 50% of animals from death. Conclusion The major mechanisms of action of PGN632 appear to be opsonization of virus and antibody-dependent cellular cytotoxicity of virally-infected cells. PS-targeting agents may have utility in the treatment of viral diseases.
Collapse
Affiliation(s)
- John M Thomas
- The University of Texas Rio Grande Valley Department of Biology; School of Medicine 1201 W. University Drive, Edinburg, Texas 78539, USA
| | - Philip E Thorpe
- The University of Texas Southwestern Medical Center Department of Pharmacology 2201 Inwood Road, Dallas, Texas 75390, USA
| |
Collapse
|
2
|
Mineo C, Lanier L, Jung E, Sengupta S, Ulrich V, Sacharidou A, Tarango C, Osunbunmi O, Shen YM, Salmon JE, Brekken RA, Huang X, Thorpe PE, Shaul PW. Identification of a Monoclonal Antibody That Attenuates Antiphospholipid Syndrome-Related Pregnancy Complications and Thrombosis. PLoS One 2016; 11:e0158757. [PMID: 27463336 PMCID: PMC4963039 DOI: 10.1371/journal.pone.0158757] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Accepted: 06/21/2016] [Indexed: 11/18/2022] Open
Abstract
In the antiphospholipid syndrome (APS), patients produce antiphospholipid antibodies (aPL) that promote thrombosis and adverse pregnancy outcomes. Current therapy with anticoagulation is only partially effective and associated with multiple complications. We previously discovered that aPL recognition of cell surface β2-glycoprotein I (β2-GPI) initiates apolipoprotein E receptor 2 (apoER2)-dependent signaling in endothelial cells and in placental trophoblasts that ultimately promotes thrombosis and fetal loss, respectively. Here we sought to identify a monoclonal antibody (mAb) to β2-GPI that negates aPL-induced processes in cell culture and APS disease endpoints in mice. In a screen measuring endothelial NO synthase (eNOS) activity in cultured endothelial cells, we found that whereas aPL inhibit eNOS, the mAb 1N11 does not, and instead 1N11 prevents aPL action. Coimmunoprecipitation studies revealed that 1N11 decreases pathogenic antibody binding to β2-GPI, and it blocks aPL-induced complex formation between β2-GPI and apoER2. 1N11 also prevents aPL antagonism of endothelial cell migration, and in mice it reverses the impairment in reendothelialization caused by aPL, which underlies the non-thrombotic vascular occlusion provoked by disease-causing antibodies. In addition, aPL inhibition of trophoblast proliferation and migration is negated by 1N11, and the more than 6-fold increase in fetal resorption caused by aPL in pregnant mice is prevented by 1N11. Furthermore, the promotion of thrombosis by aPL is negated by 1N11. Thus, 1N11 has been identified as an mAb that attenuates APS-related pregnancy complications and thrombosis in mice. 1N11 may provide an efficacious, mechanism-based therapy to combat the often devastating conditions suffered by APS patients.
Collapse
Affiliation(s)
- Chieko Mineo
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (CM); (PWS)
| | - Lane Lanier
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Eunjeong Jung
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Samarpita Sengupta
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Victoria Ulrich
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Anastasia Sacharidou
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Cristina Tarango
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Olutoye Osunbunmi
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Yu-Min Shen
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Jane E. Salmon
- Department of Medicine, Hospital for Special Surgery, Weill Cornell Medical College, New York, New York, United States of America
| | - Rolf A. Brekken
- Department of Pharmacology and the Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Department of Surgery, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Xianming Huang
- Department of Pharmacology and the Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Philip E. Thorpe
- Department of Pharmacology and the Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Philip W. Shaul
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- * E-mail: (CM); (PWS)
| |
Collapse
|
3
|
Wojtukiewicz MZ, Sierko E, Skalij P, Kamińska M, Zimnoch L, Brekken RA, Thorpe PE. Granulocyte-Colony Stimulating Factor Receptor, Tissue Factor, and VEGF-R Bound VEGF in Human Breast Cancer In Loco. ADV CLIN EXP MED 2016; 25:505-11. [PMID: 27629739 DOI: 10.17219/acem/62398] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 12/10/2015] [Accepted: 03/30/2016] [Indexed: 11/24/2022]
Abstract
BACKGROUND Doxorubicin and docetaxel-based chemotherapy regimens used in breast cancer patients are associated with high risk of febrile neutropenia (FN). Granulocyte colony-stimulating factors (G-CSF) are recommended for both treating and preventing chemotherapy-induced neutropenia. Increased thrombosis incidence in G-CSF treated patients was reported; however, the underlying mechanisms remain unclear. The principal activator of blood coagulation in cancer is tissue factor (TF). It additionally contributes to cancer progression and stimulates angiogenesis. The main proangiogenic factor is vascular endothelial growth factor (VEGF). OBJECTIVES The aim of the study was to evaluate granulocyte-colony stimulating factor receptor (G-CSFR), tissue factor (TF) expression and vascular endothelial growth factor receptor (VEGF-R) bound VEGF in human breast cancer in loco. MATERIAL AND METHODS G-CSFR, TF and VEGFR bound VEGF (VEGF: VEGFR) were assessed in 28 breast cancer tissue samples. Immunohistochemical (IHC) methodologies according to ABC technique and double staining IHC procedure were employed utilizing antibodies against G-CSFR, TF and VEGF associated with VEGFR (VEGF: VEGFR). RESULTS Expression of G-CSFR was demonstrated in 20 breast cancer tissue specimens (71%). In 6 cases (21%) the expression was strong (IRS 9-12). Strong expression of TF was observed in all investigated cases (100%). Moreover, expression of VEGF: VEGFR was visualized in cancer cells (IRS 5-8). No presence of G-CSFR, TF or VEGF: VEGFR was detected on healthy breast cells. Double staining IHC studies revealed co-localization of G-CSFR and TF, G-CSFR and VEGF: VEGFR, as well as TF and VEGF: VEGFR on breast cancer cells and ECs. CONCLUSIONS The results of the study indicate that GCSFR, TF and VEGF: VEGFR expression as well as their co-expression might influence breast cancer biology, and may increase thromboembolic adverse events incidence.
Collapse
Affiliation(s)
- Marek Z Wojtukiewicz
- Department of Oncology, Medical University of Bialystok, Poland
- Comprehensive Cancer Center, Białystok, Poland
| | - Ewa Sierko
- Department of Oncology, Medical University of Bialystok, Poland
- Comprehensive Cancer Center, Białystok, Poland
| | - Piotr Skalij
- Department of Oncology, Medical University of Bialystok, Poland
- Comprehensive Cancer Center, Białystok, Poland
| | - Magda Kamińska
- Department of Oncology, Medical University of Bialystok, Poland
- Comprehensive Cancer Center, Białystok, Poland
| | - Lech Zimnoch
- Department of Pathomorphology, Medical University of Bialystok, Poland
| | - Ralf A Brekken
- Department of Pharmacology, UT-Southwestern Medical Center, Dallas, TX, USA
| | - Philip E Thorpe
- Hamon Center for Therapeutic Oncology Research, UT Southwestern Medical Center, Dallas, TX, USA
| |
Collapse
|
4
|
Cheng X, Li L, Thorpe PE, Yopp AC, Brekken RA, Huang X. Antibody-Mediated Blockade of Phosphatidylserine Enhances the Antitumor Effect of Sorafenib in Hepatocellular Carcinomas Xenografts. Ann Surg Oncol 2016; 23:583-591. [PMID: 26847681 DOI: 10.1245/s10434-016-5107-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2015] [Indexed: 12/21/2022]
Abstract
BACKGROUND Currently, the only FDA-approved systemic therapy for hepatocellular carcinoma (HCC) is the multi-receptor tyrosine kinase inhibitor, sorafenib, which provides only modest clinical benefit. We recently showed that treatment with a phosphatidylserine (PS) targeting agent suppresses tumor growth by targeting tumor vasculature and reactivating antitumor immunity. METHODS We tested the hypothesis that sorafenib increases PS exposure on tumor vasculature, thereby enhancing the antitumor efficacy of PS targeting. We evaluated the efficacy of combining a PS targeting agent (2aG4) with sorafenib in murine xenograft models of human HCC. RESULTS Our results demonstrate that combination of 2aG4 and sorafenib had a superior therapeutic effect over single agent therapy. Mechanistic studies showed that sorafenib significantly increased PS exposure on tumor vasculature; the percentage of PS-positive vessels increased from 19 to 52, 23 to 68, and 30 to 55 % in PLC/PRF/5, C3A, and Huh7 tumors, respectively. Combination therapy significantly decreased tumor microvessel density and the level of M2 macrophages, while increasing the apoptotic index of tumor endothelial cells and the frequency of M1 macrophages. Furthermore, we report the findings of a Phase I clinical study of bavituximab, a chimeric version of 2aG4, combined with sorafenib in HCC patients. The Phase I results demonstrate the appropriate dose of bavituximab to be given with sorafenib in future clinical trials. CONCLUSIONS Overall, these results strongly support the combination of bavituximab with sorafenib as a promising systemic therapeutic strategy for the treatment for advanced HCC patients.
Collapse
Affiliation(s)
- Xiaoyun Cheng
- Hamon Center for Therapeutic Oncology Research, UT Southwestern Medical Center, Dallas, TX, USA
| | - Li Li
- Hamon Center for Therapeutic Oncology Research, UT Southwestern Medical Center, Dallas, TX, USA
| | - Philip E Thorpe
- Hamon Center for Therapeutic Oncology Research, UT Southwestern Medical Center, Dallas, TX, USA.,Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Adam C Yopp
- Division of Surgical Oncology, Department of Surgery, UT Southwestern Medical Center, Dallas, TX, USA
| | - Rolf A Brekken
- Hamon Center for Therapeutic Oncology Research, UT Southwestern Medical Center, Dallas, TX, USA. .,Division of Surgical Oncology, Department of Surgery, UT Southwestern Medical Center, Dallas, TX, USA. .,Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA.
| | - Xianming Huang
- Hamon Center for Therapeutic Oncology Research, UT Southwestern Medical Center, Dallas, TX, USA. .,Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX, USA.
| |
Collapse
|
5
|
Gerber DE, Hao G, Watkins L, Stafford JH, Anderson J, Holbein B, Öz OK, Mathews D, Thorpe PE, Hassan G, Kumar A, Brekken RA, Sun X. Tumor-specific targeting by Bavituximab, a phosphatidylserine-targeting monoclonal antibody with vascular targeting and immune modulating properties, in lung cancer xenografts. Am J Nucl Med Mol Imaging 2015; 5:493-503. [PMID: 26550540 PMCID: PMC4620176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Accepted: 06/19/2015] [Indexed: 06/05/2023]
Abstract
Bavituximab is a chimeric monoclonal antibody with immune modulating and tumor-associated vascular disrupting properties demonstrated in models of non-small cell lung cancer (NSCLC). The molecular target of Bavituximab, phosphatidylserine (PS), is exposed on the outer leaflet of the membrane bi-layer of malignant vascular endothelial cells and tumor cells to a greater extent than on normal tissues. We evaluated the tumor-targeting properties of Bavituximab for imaging of NSCLC xenografts when radiolabeled with (111)In through conjugation with a bifunctional chelating agent, 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA). In vitro binding of (111)In-DOTA-Bavituximab to PS was determined by enzyme-linked immunosorbent assay (ELISA). Biodistribution of (111)In-DOTA-Bavituximab was conducted in normal rats, which provided data for dosimetry calculation. Single-photon emission computed tomography/computed tomography (SPECT/CT) imaging was performed in athymic nude rats bearing A549 NSCLC xenografts. At the molar conjugation ratio of 0.54 DOTA per Bavituximab, the PS binding affinity of (111)In-DOTA-Bavituximab was comparable to that of unmodified Bavituximab. Based on the quantitative SPECT/CT imaging data analysis, (111)In-DOTA-Bavituximab demonstrated tumor-specific uptake as measured by the tumor-tomuscle ratio, which peaked at 5.2 at 72 hr post-injection. In contrast, the control antibody only presented a contrast of 1.2 at the same time point.These findings may underlie the diagnostic efficacy and relative low rates of systemic vascular and immune-related toxicities of this immunoconjugate. Future applications of (111)In-DOTA-bavituximab may include prediction of efficacy, indication of tumor immunologic status, or characterization of radiographic findings.
Collapse
Affiliation(s)
- David E Gerber
- Division of Hematology-Oncology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA ; Department of Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Guiyang Hao
- Department of Radiology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Linda Watkins
- Department of Pharmacology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Jason H Stafford
- Department of Pharmacology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA ; Current Address: Stanford University Medical Center USA
| | - Jon Anderson
- Department of Radiology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Blair Holbein
- Department of Clinical Sciences, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Orhan K Öz
- Department of Radiology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Dana Mathews
- Department of Radiology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Philip E Thorpe
- Department of Pharmacology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA ; Department of Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Gedaa Hassan
- Department of Radiology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Amit Kumar
- Department of Radiology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Rolf A Brekken
- Department of Surgery, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA ; Department of Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| | - Xiankai Sun
- Department of Radiology, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA ; Department of Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center Dallas, Texas 75390-8852, USA
| |
Collapse
|
6
|
Zhou H, Stafford JH, Hallac RR, Zhang L, Huang G, Mason RP, Gao J, Thorpe PE, Zhao D. Phosphatidylserine-targeted molecular imaging of tumor vasculature by magnetic resonance imaging. J Biomed Nanotechnol 2014; 10:846-55. [PMID: 24734537 DOI: 10.1166/jbn.2014.1851] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Phosphatidylserine (PS), normally restricted to the inner leaflet of the plasma membrane, becomes exposed on the outer surface of viable endothelial cells in tumor vasculature, but not in normal blood vessels. In the present study, we report the use of PGN635, a novel human monoclonal antibody that specifically targets PS, for in vivo molecular MRI of tumor vasculature. The F(ab')2 fragments of PGN635 were conjugated to polyethylene glycol (PEG) coated iron oxide nanoparticles (IO). Targeting specificity of the PS-targeted Nanoprobe, IO-PGN635F(ab')2 was first confirmed by in vitro MRI and histological staining. In vivo longitudinal MRI was then performed before and after i.v. injection of IO-PGN635F(ab')2 into mice bearing 4T1 breast tumors. T2-weighted MR images at 9.4 T revealed inhomogeneous signal loss in tumor as early as 2 h post injection. Furthermore, ionizing radiation induced a significant increase in PS exposure on tumor vascular endothelial cells, resulting in significantly enhanced and sustained tumor contrast (p < 0.05). Spatially heterogeneous MRI contrast correlated well with histological staining of tumor vascular endothelium. Our studies suggest that PS exposed within the lumen of tumor vasculature is a highly specific and useful biomarker for targeted MRI contrast agents.
Collapse
MESH Headings
- Animals
- Cell Line, Tumor
- Magnetic Resonance Imaging/methods
- Magnetite Nanoparticles
- Mice
- Mice, Inbred BALB C
- Mice, Nude
- Molecular Imaging/methods
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Neoplasms, Experimental/radiotherapy
- Neovascularization, Pathologic/metabolism
- Neovascularization, Pathologic/pathology
- Neovascularization, Pathologic/radiotherapy
- Phosphatidylserines/pharmacokinetics
- Radiotherapy, Conformal
- Reproducibility of Results
- Sensitivity and Specificity
- Treatment Outcome
Collapse
|
7
|
Stafford JH, Hao G, Best AM, Sun X, Thorpe PE. Highly specific PET imaging of prostate tumors in mice with an iodine-124-labeled antibody fragment that targets phosphatidylserine. PLoS One 2013; 8:e84864. [PMID: 24367699 PMCID: PMC3868598 DOI: 10.1371/journal.pone.0084864] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 11/20/2013] [Indexed: 02/07/2023] Open
Abstract
Phosphatidylserine (PS) is an attractive target for imaging agents that identify tumors and assess their response to therapy. PS is absent from the surface of most cell types, but becomes exposed on tumor cells and tumor vasculature in response to oxidative stresses in the tumor microenvironment and increases in response to therapy. To image exposed PS, we used a fully human PS-targeting antibody fragment, PGN635 F(ab’)2, that binds to complexes of PS and β2-glycoprotein I. PGN635 F(ab’)2 was labeled with the positron-emitting isotope iodine-124 (124I) and the resulting probe was injected into nude mice bearing subcutaneous or orthotopic human PC3 prostate tumors. Biodistribution studies showed that 124I-PGN635 F(ab’)2 localized with remarkable specificity to the tumors with little uptake in other organs, including the liver and kidneys. Clear delineation of the tumors was achieved by PET 48 hours after injection. Radiation of the tumors with 15 Gy or systemic treatment of the mice with 10 mg/kg docetaxel increased localization in the tumors. Tumor-to-normal (T/N) ratios were inversely correlated with tumor growth measured over 28 days. These data indicate that 124I-PGN635 F(ab’)2 is a promising new imaging agent for predicting tumor response to therapy.
Collapse
Affiliation(s)
- Jason H. Stafford
- Department of Pharmacology, The Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- *
| | - Guiyang Hao
- Department of Radiology, The Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Anne M. Best
- Department of Pharmacology, The Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Xiankai Sun
- Department of Radiology, The Advanced Imaging Research Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Philip E. Thorpe
- Department of Pharmacology, The Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| |
Collapse
|
8
|
Thorpe PE. Identification and Treatment of Restenosis in Failing Venous Stents: The Role of Intravascular Ultrasound. J Vasc Surg Venous Lymphat Disord 2013; 2:109-10. [PMID: 26992995 DOI: 10.1016/j.jvsv.2013.10.020] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
9
|
Yin Y, Huang X, Lynn KD, Thorpe PE. Phosphatidylserine-targeting antibody induces M1 macrophage polarization and promotes myeloid-derived suppressor cell differentiation. Cancer Immunol Res 2013; 1:256-68. [PMID: 24777853 DOI: 10.1158/2326-6066.cir-13-0073] [Citation(s) in RCA: 107] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Multiple tumor-derived factors are responsible for the accumulation and expansion of immune-suppressing myeloid-derived suppressor cells (MDSC) and M2-like tumor-associated macrophages (TAM) in tumors. Here, we show that treatment of tumor-bearing mice with docetaxel in combination with the phosphatidylserine-targeting antibody 2aG4 potently suppressed the growth and progression of prostate tumors, depleted M2-like TAMs, and MDSCs, and increased the presence of M1-like TAMs and mature dendritic cells in the tumors. In addition, the antibody markedly altered the cytokine balance in the tumor microenvironment from immunosuppressive to immunostimulatory. In vitro studies confirmed that 2aG4 repolarized TAMs from an M2- to an M1-like phenotype and drove the differentiation of MDSCs into M1-like TAMs and functional dendritic cells. These data suggest that phosphatidylserine is responsible for the expansion of MDSCs and M2-like TAMs in tumors, and that bavituximab, a phosphatidylserine-targeting antibody currently in clinical trials for cancer, could reverse this process and reactivate antitumor immunity.
Collapse
Affiliation(s)
- Yi Yin
- Authors' Affiliation: Department of Pharmacology and Simmons and Hamon Cancer Centers, University of Texas Southwestern Medical Center, Dallas, Texas
| | | | | | | |
Collapse
|
10
|
Wanderley JLM, Thorpe PE, Barcinski MA, Soong L. Phosphatidylserine exposure on the surface of Leishmania amazonensis amastigotes modulates in vivo infection and dendritic cell function. Parasite Immunol 2013; 35:109-119. [PMID: 23163958 DOI: 10.1111/pim.12019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Accepted: 10/23/2012] [Indexed: 12/14/2022]
Abstract
Leishmania amazonensis parasites can cause diverse forms of leishmaniasis in humans and persistent lesions in most inbred strains of mice. In both cases, the infection is characterized by a marked immunosuppression of the host. We previously showed that amastigote forms of the parasite make use of surface-exposed phosphatidylserine (PS) molecules to infect host cells and promote alternative macrophage activation, leading to uncontrolled intracellular proliferation of the parasites. In this study, we demonstrated that treatment of infected mice with a PS-targeting monoclonal antibody ameliorated parasite loads and lesion development, which correlated with increased proliferative responses by lymphocytes. In addition, we observed an enhanced dendritic cell (DC) activation and antigen presentation in vitro. Our data imply that the recognition of PS exposed on the surface of amastigotes plays a role in down-modulating DC functions, in a matter similar to that of apoptotic cell clearance. This study provides new information regarding the mechanism of immune suppression in Leishmania infection.
Collapse
Affiliation(s)
- J L M Wanderley
- Morphological Sciences Program, Biomedical Sciences Institute, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,Campus UFRJ Macaé, Pólo Universitário, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.,Department of Microbiology and Immunology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA
| | - P E Thorpe
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - M A Barcinski
- Parasitology Department, Biomedical Sciences Institute, University of Sao Paulo, Sao Paulo, Brazil.,Laboratory of Cellular Biology, Institute Oswaldo Cruz, Rio de Janeiro, RJ, Brazil
| | - L Soong
- Department of Microbiology and Immunology, Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, USA.,Department of Pathology, Center for Biodefense and Emerging Infectious Diseases, Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, TX, USA
| |
Collapse
|
11
|
Mohamedali KA, Niu G, Luster TA, Thorpe PE, Gao H, Chen X, Rosenblum MG. Pharmacodynamics, tissue distribution, toxicity studies and antitumor efficacy of the vascular targeting fusion toxin VEGF121/rGel. Biochem Pharmacol 2012; 84:1534-40. [PMID: 23022224 DOI: 10.1016/j.bcp.2012.09.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Revised: 09/16/2012] [Accepted: 09/18/2012] [Indexed: 11/30/2022]
Abstract
As a part of an ongoing assessment of its mechanism of action, we evaluated the in vivo pharmacokinetics, tissue distribution, toxicity and antitumor efficacy of VEGF(121)/rGel, a novel fusion protein. Pharmacokinetic studies showed that VEGF(121)/rGel cleared from the circulation in a biphasic manner with calculated half-lives of 0.3 and 6h for the alpha and beta phases, respectively. Pharmacokinetic evaluation of (64)Cu-DOTA-VEGF(121)/rGel showed relatively high blood retention 30 min after injection (26.6 ± 1.73% ID/g), dropping to 11.8 ± 2.83% and 0.82 ± 0.11% ID/g at 60 and 240 min post injection, respectively. Tissue uptake studies showed that kidneys, liver and tumor had the highest drug concentrations 48 h after administration. The maximum tolerated dose (MTD), based on a QOD×5 i.v. administration schedule, was found to be 18 mg/kg with an LD(50) of 25mg/kg. Treatment of BALB/c mice with VEGF(121)/rGel at doses up to the MTD caused no alterations in hematologic parameters. However, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) parameters increased in a dose-related manner. The no-observable-adverse-effect-level (NOAEL) was determined to be 20% of the MTD (3.6 mg/kg). VEGF(121)/rGel treatment of mice bearing orthotopically-placed MDA-MB-231 breast tumors caused increased vascular permeability of tumor tissue by 53% compared to saline-treated controls. Immunohistochemical analysis showed significant tumor hypoxia and necrosis as a consequence of vascular damage. In summary, VEGF(121)/rGel appears to be an effective therapeutic agent causing focused damage to tumor vasculature with minimal toxic effects to normal organs. This agent appears to be an excellent candidate for further clinical development.
Collapse
Affiliation(s)
- Khalid A Mohamedali
- Department of Experimental Therapeutics, The University of Texas M.D. Anderson Cancer Center, Houston, 77030, United States.
| | | | | | | | | | | | | |
Collapse
|
12
|
Marquardt J, Begent RHJ, Chester K, Huston JS, Bradbury A, Scott JK, Thorpe PE, Veldman T, Reichert JM, Weiner LM. IBC's 23rd Antibody Engineering and 10th Antibody Therapeutics Conferences and the Annual Meeting of The Antibody Society: December 2-6, 2012, San Diego, CA. MAbs 2012; 4:648-52. [PMID: 23007482 PMCID: PMC3502231 DOI: 10.4161/mabs.22221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Now in its 23rd and 10th years, respectively, the Antibody Engineering and Antibody Therapeutics conferences are the Annual Meeting of The Antibody Society. The scientific program covers the full spectrum of challenges in antibody research and development from basic science through clinical development. In this preview of the conferences, the chairs provide their thoughts on sessions that will allow participants to track emerging trends in (1) the development of next-generation immunomodulatory antibodies; (2) the complexity of the environment in which antibodies must function; (3) antibody-targeted central nervous system (CNS) therapies that cross the blood brain barrier; (4) the extension of antibody half-life for improved efficacy and pharmacokinetics (PK)/pharmacodynamics (PD); and (5) the application of next generation DNA sequencing to accelerate antibody research. A pre-conference workshop on Sunday, December 2, 2012 will update participants on recent intellectual property (IP) law changes that affect antibody research, including biosimilar legislation, the America Invents Act and recent court cases. Keynote presentations will be given by Andreas Plückthun (University of Zürich), who will speak on engineering receptor ligands with powerful cellular responses; Gregory Friberg (Amgen Inc.), who will provide clinical updates of bispecific antibodies; James D. Marks (University of California, San Francisco), who will discuss a systems approach to generating tumor targeting antibodies; Dario Neri (Swiss Federal Institute of Technology Zürich), who will speak about delivering immune modulators at the sites of disease; William M. Pardridge (University of California, Los Angeles), who will discuss delivery across the blood-brain barrier; and Peter Senter (Seattle Genetics, Inc.), who will present his vision for the future of antibody-drug conjugates. For more information on these meetings or to register to attend, please visit www.IBCLifeSciences.com/AntibodyEng or call 800-390-4078. Members of The Antibody Society and mAbs journal subscribers receive a 20% discount for meeting registration. To obtain this discount, email kdostie@ibcusa.com. mAbs is the official therapeutics journal of The Antibody Society and offers a discounted subscription to Society members for $49.
Collapse
|
13
|
Kirov A, Al-Hashimi H, Solomon P, Mazur C, Thorpe PE, Sims PJ, Tarantini F, Kumar TKS, Prudovsky I. Phosphatidylserine externalization and membrane blebbing are involved in the nonclassical export of FGF1. J Cell Biochem 2012; 113:956-66. [PMID: 22034063 DOI: 10.1002/jcb.23425] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The mechanisms of nonclassical export of signal peptide-less proteins remain insufficiently understood. Here, we demonstrate that stress-induced unconventional export of FGF1, a potent and ubiquitously expressed mitogenic and proangiogenic protein, is associated with and dependent on the formation of membrane blebs and localized cell surface exposure of phosphatidylserine (PS). In addition, we found that the differentiation of promonocytic cells results in massive FGF1 release, which also correlates with membrane blebbing and exposure of PS. These findings indicate that the externalization of acidic phospholipids could be used as a pharmacological target to regulate the availability of FGF1 in the organism.
Collapse
Affiliation(s)
- Aleksandr Kirov
- Maine Medical Center Research Institute, Scarborough, Maine Medical Center, ME 04074, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Yin Y, Huang X, Barbero G, Ye D, Thorpe PE. Abstract 4395: Cure of castration-resistant prostate cancer in TRAMP mice by reactivating tumor immunity with a phosphatidylserine-targeting antibody. Cancer Res 2012. [DOI: 10.1158/1538-7445.am2012-4395] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Androgen deprivation therapy (ADT) is initially effective against prostate cancer, but many patients eventually relapse and die from the outgrowth of castration-resistant disease. Here, we tested the hypothesis that tumor immunity against castration-resistant prostate cancer can be elicited by combining ADT with treatment with a monoclonal antibody that binds exposed phosphatidylserine (PS). The rationale was that PS is an immunosuppressive lipid that becomes exposed on tumor blood vessels and malignant cells in prostate tumors responding to ADT, and inhibits immune responses to prostate tumor antigens. To validate this hypothesis, we castrated TRAMP mice after they had developed prostatic adenocarcinomas and treated them with the PS-targeting antibody, mch1N11. We first demonstrated that PS exposure was induced on tumor vascular endothelium and tumor cells by castration. PS exposure on vessels coincided with regions of hypoxia generated in the tumor microenvironment. Next, we demonstrated that castration combined with treatment with mch1N11 inhibited tumor growth and progression. About half of the treated TRAMP mice did not develop castration-resistant tumors, and eventually died of old age. Immunohistochemical studies revealed that the mch1N11 treatment combined with castration generated T-cell immune responses against TRAMP tumor antigens that kept the tumor in check. Extensive disruption of tumor vasculature and abundant infiltration of immune cells, including CD8 positive T lymphocytes, Natural killer (NK) cells and dendritic cells were observed. Splenocytes from mice treated with mch1N11 plus castration were able to kill TRAMP-C2 specifically in vitro, whereas splenocytes from mice in the other groups could not. These results demonstrate that PS, which becomes exposed on prostate cancer cells and tumor vasculature after ADT, inhibits immunity to TRAMP tumor antigens. Treatment with the PS-targeting antibody mch1N11 reactivates tumor immunity, which can permanently hold new tumor development in check.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4395. doi:1538-7445.AM2012-4395
Collapse
Affiliation(s)
- Yi Yin
- 1UT Southwestern Medical Ctr., Dallas, TX
| | | | | | - Dan Ye
- 1UT Southwestern Medical Ctr., Dallas, TX
| | | |
Collapse
|
15
|
DeRose P, Thorpe PE, Gerber DE. Development of bavituximab, a vascular targeting agent with immune-modulating properties, for lung cancer treatment. Immunotherapy 2011; 3:933-44. [PMID: 21843081 DOI: 10.2217/imt.11.87] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Bavituximab is a chimeric monoclonal antibody directed against the membrane phospholipid phosphatidylserine. Phosphatidylserine exposure is increased on endothelial cells and apoptotic cancer cells in solid tumors, allowing tumor-specific targeting of bavituximab. Bavituximab binding results in tumor vessel occlusion and enhanced antitumor immunity. Preclinical investigations have demonstrated efficacy as monotherapy and in combination with other modalities against multiple cancer types. Phase I clinical trials of bavituximab monotherapy and in combination with chemotherapy in adults with refractory solid tumors have been completed. Phase II trials of bavituximab in combination with chemotherapy for the first- and second-line treatment of advanced non-small-cell lung cancer are currently ongoing. This article summarizes the preclinical development and clinical experience with bavituximab in non-small-cell lung cancer.
Collapse
Affiliation(s)
- Paul DeRose
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | | |
Collapse
|
16
|
Gerber DE, Stopeck AT, Wong L, Rosen LS, Thorpe PE, Shan JS, Ibrahim NK. Phase I safety and pharmacokinetic study of bavituximab, a chimeric phosphatidylserine-targeting monoclonal antibody, in patients with advanced solid tumors. Clin Cancer Res 2011; 17:6888-96. [PMID: 21989064 DOI: 10.1158/1078-0432.ccr-11-1074] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE Bavituximab is a chimeric immunoglobulin G1 phosphatidylserine-targeting monoclonal antibody that triggers vascular disruption and enhances antitumor immune response. This phase I study assessed the safety and pharmacokinetics of bavituximab in patients with advanced solid tumors. EXPERIMENTAL DESIGN Patients with refractory advanced solid tumors were enrolled into four sequential dose-escalation cohorts (0.1, 0.3, 1, or 3 mg/kg bavituximab weekly) with two dosing schedules. Patients in the 0.1 and 0.3 mg/kg cohorts received bavituximab on days 0, 28, 35, and 42. Patients in the 1 and 3 mg/kg cohorts were administered bavituximab on days 0, 7, 14, and 21. Safety, pharmacokinetics, and tumor response were assessed. RESULTS Twenty-six patients were accrued. No maximum tolerated dose was reached. Six serious adverse events occurred in five patients, including one pulmonary embolism at 3 mg/kg, which was the only dose-limiting toxicity (DLT) in the study. Bavituximab half-life ranged from 37 to 47 hours, with no accumulation seen following administration of multiple doses. Activated partial thromboplastin time was modestly prolonged in vitro at the highest dose tested. As assessed on day 56, a total of 18 patients were evaluable for efficacy, of whom 10 had disease progression and none had an objective response. CONCLUSIONS Bavituximab was well tolerated at doses ranging up to 3 mg/kg weekly. Pharmacokinetic studies support a weekly dosing regimen. Additional phase I and II clinical trials are in progress to investigate bavituximab in combination with chemotherapy and other molecularly targeted agents.
Collapse
Affiliation(s)
- David E Gerber
- Harold C. Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | | | | | | | | | | |
Collapse
|
17
|
Mohamedali KA, Ran S, Gomez-Manzano C, Ramdas L, Xu J, Kim S, Cheung LH, Hittelman WN, Zhang W, Waltenberger J, Thorpe PE, Rosenblum MG. Cytotoxicity of VEGF(121)/rGel on vascular endothelial cells resulting in inhibition of angiogenesis is mediated via VEGFR-2. BMC Cancer 2011; 11:358. [PMID: 21849059 PMCID: PMC3176242 DOI: 10.1186/1471-2407-11-358] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 08/17/2011] [Indexed: 12/27/2022] Open
Abstract
Background The fusion protein VEGF121/rGel composed of the growth factor VEGF121 and the plant toxin gelonin targets the tumor neovasculature and exerts impressive anti-vascular effects. We have previously shown that VEGF121/rGel is cytotoxic to endothelial cells overexpressing VEGFR-2 but not to endothelial cells overexpressing VEGFR-1. In this study, we examined the basis for the specific toxicity of this construct and assessed its intracellular effects in vitro and in vivo. Methods We investigated the binding, cytotoxicity and internalization profile of VEGF121/rGel on endothelial cells expressing VEGFR-1 or VEGFR-2, identified its effects on angiogenesis models in vitro and ex vivo, and explored its intracellular effects on a number of molecular pathways using microarray analysis. Results Incubation of PAE/VEGFR-2 and PAE/VEGFR-1 cells with 125I-VEGF121/rGel demonstrated binding specificity that was competed with unlabeled VEGF121/rGel but not with unlabeled gelonin. Assessment of the effect of VEGF121/rGel on blocking tube formation in vitro revealed a 100-fold difference in IC50 levels between PAE/VEGFR-2 (1 nM) and PAE/VEGFR-1 (100 nM) cells. VEGF121/rGel entered PAE/VEGFR-2 cells within one hour of treatment but was not detected in PAE/VEGFR-1 cells up to 24 hours after treatment. In vascularization studies using chicken chorioallantoic membranes, 1 nM VEGF121/rGel completely inhibited bFGF-stimulated neovascular growth. The cytotoxic effects of VEGF121/rGel were not apoptotic since treated cells were TUNEL-negative with no evidence of PARP cleavage or alteration in the protein levels of select apoptotic markers. Microarray analysis of VEGF121/rGel-treated HUVECs revealed the upregulation of a unique "fingerprint" profile of 22 genes that control cell adhesion, apoptosis, transcription regulation, chemotaxis, and inflammatory response. Conclusions Taken together, these data confirm the selectivity of VEGF121/rGel for VEGFR-2-overexpressing endothelial cells and represent the first analysis of genes governing intoxication of mammalian endothelial cells by a gelonin-based targeted therapeutic agent.
Collapse
Affiliation(s)
- Khalid A Mohamedali
- Departments of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, TX, USA.
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Huang X, Ye D, Thorpe PE. Enhancing the potency of a whole-cell breast cancer vaccine in mice with an antibody-IL-2 immunocytokine that targets exposed phosphatidylserine. Vaccine 2011; 29:4785-93. [PMID: 21557977 DOI: 10.1016/j.vaccine.2011.04.082] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 04/20/2011] [Accepted: 04/21/2011] [Indexed: 01/22/2023]
Abstract
Phosphatidylserine (PS), an anionic phospholipid normally restricted to the inner leaflet of the plasma membrane, is immunosuppressive when externalized on the outside of cell membranes. Exposed PS inhibits the maturation and function of dendritic cells (DCs), and induces the production of multiple immunosuppressive mediators. In the present study, we determined whether blocking these effects of PS while simultaneously introducing interleukin-2 (IL-2) could improve the immunogenicity of a whole-cell cancer vaccine. An immunocytokine (2aG4-IL2) was made by genetically linking IL-2 with a PS targeting antibody, 2aG4, that can block the immunosuppressive effects of PS. The 2aG4-IL2/4T1 vaccine was generated by coating the PS exposed on irradiated 4T1 cells with 2aG4-IL2. Tumor growth, spontaneous metastasis, and survival of vaccinated mice challenged with live 4T1 tumor cells were assessed. Eighty percent of mice inoculated with 2aG4-IL2/4T1 vaccine survived free of tumor, as compared with 20% in the 2aG4/4T1 group, 20% in the C44-IL2/4T1 group, and none in the C44/4T1 control group (P=0.001 for 2aG4-IL2/4T1 versus all others groups). The incidence, number of spontaneous lung metastases was significantly lower in the 2aG4-IL2/4T1 vaccinated group than in the other groups. Splenocytes from 2aG4-IL2/4T1 vaccinated mice had significantly higher 4T1 specific cytotoxicity and ability to secrete interferon-gamma (IFNγ) than did splenocytes from mice in the other groups. These results demonstrate that a potent whole-cell vaccine can be created by coating irradiated tumor cells with 2aG4-IL2. Such vaccine could potentially be an effective treatment modality for patients with residual disease or at "high-risk" for recurrence.
Collapse
Affiliation(s)
- Xianming Huang
- Simmons Comprehensive Cancer Center, the Department of Pharmacology, the University of Texas Southwestern Medical Center, Dallas, TX 75390-9041, USA
| | | | | |
Collapse
|
19
|
Abstract
Abstract
Androgen deprivation therapy (ADT) is effective against androgen-dependent prostate cancer, but patients usually relapse from the outgrowth of androgen-independent disease. Here, we tested the hypothesis that relapse can be prevented by combining ADT with treatment with a monoclonal antibody that binds exposed phosphatidylserine (PS). The rationale behind this hypothesis is that ADT will create hypoxia which induces PS exposure on the tumor vascular endothelial cells, leading to immune cell attack on tumor vasculature, collapse of the vessels and death of hormone-resistant and hormone-sensitive tumor cells through deprivation of oxygen and nutrients. In addition, the antibody should block the immunosuppressive effects of PS and induce reactivation of T-cell immunity. To test this hypothesis, we used ADT and anti-PS antibodies (2aG4 or murine chimeric 1N11) to treat mice bearing hormone-sensitive prostate tumors. The tumor models were: i) immunocompromised mice bearing human LNCaP prostate tumors; ii) transgenic (TRAMP) mice which spontaneously develop adenocarcinoma of the mouse prostate. Castration induced exposure of PS on blood vessels and tumor cells in both models. Vascular PS exposure corresponded with hypoxia, as judged by pimonidazole staining. In the LNCaP model, castration alone delayed tumor growth but all animals relapsed with hormone-independent disease, whereas mice treated with castration plus anti-PS antibody did not relapse. In TRAMP mice castrated at 15-weeks of age, only 54% (7/13) of mice treated with castration alone survived beyond 40-weeks of age, as compared with 92% (12/13) of mice treated with castration and 1N11. No toxicity to the mice was caused by the antibody treatment. Tumor blood flow and perfusion were markedly reduced in mice treated with castration and anti-PS antibody. Histological studies revealed extensive disruption of tumor vasculature and abundant infiltration of immune cells, principally M1 macrophages. These results demonstrate that PS becomes exposed on prostate cancer tumor vasculature and tumor cells in response to hypoxia caused by ADT in the tumor microenvironment. The exposed PS could serve as a target to enhance the efficacy of ADT against prostate cancer.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 621. doi:10.1158/1538-7445.AM2011-621
Collapse
Affiliation(s)
- Yi Yin
- 1UT Southwestern Medical Center, Dallas, TX
| | | |
Collapse
|
20
|
Cheng X, Thorpe PE. Abstract 3643: Phosphatidylserine-targeting antibody combined with Sorafenib has strong anti-tumor activity against human hepatocellular carcinomas in mice. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-3643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Hepatocellular Carcinoma (HCC) is the third leading cause of cancer-related deaths in the world. The incidence of the HCC is increasing in the United States. HCC is refractory to most forms of therapy. Sorafenib is the only chemotherapeutic agent approved for the treatment of advanced HCC. Therefore, there is a huge unmet need for a new systemic therapy for HCC patients. A promising approach would be to combine sorafenib with bavituximab to treat HCC. Bavituximab is a vascular targeting antibody that is in Phase IIb clinical trials in patients with non-small cell lung cancer (NSCLC). Bavituximab targets phosphatidylserine (PS), which is normally intracellular but becomes exposed on the external surface of vascular endothelium in tumors. Bavituximab binds to PS-expressing tumor vascular endothelial cells and causes monocytes and macrophages to attack the vessels by antibody-dependent cellular cytotoxicity (ADCC). This results in death of tumor cells through deprivation of oxygen and nutrients. Chemotherapy and irradiation increase the exposure of PS on tumor vessels and enhance the anti-tumor activity of bavituximab-related antibodies in multiple rodent tumor models. We hypothesized that sorafenib would also induce exposure of PS on HCC vasculature because it interferes with anti-apoptotic signaling by VEGF and other angiogenic growth factors. We found that sorafenib induced PS exposure on human microvascular endothelial cells in vitro and in vivo. Treatment of mice bearing subcutaneous C3A, Huh7 or PLC/PRF/5 HCC tumors with sorafenib increased PS exposure on tumor vessels from 21% to 51% in PLC/PRF/5 tumors, from 22% to 67% in C3A tumors, and from 32% to 52% in Huh7 tumors. Combining a murine version of bavituximab with sorafenib significantly improved the anti-tumor effect in the PLC/PRF/5 xenograft model. The combination inhibited tumor growth by 95%, as compared with 80% for sorafenib alone (p<0.05). Bavituximab in combination with sorafenib has promise as a new systemic therapy for the treatment of advanced HCC patients.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3643. doi:10.1158/1538-7445.AM2011-3643
Collapse
|
21
|
Huang X, Ye D, Thorpe PE. Abstract 3651: Phosphatidylserine-targeting antibody induces differentiation of myeloid-derived suppressor cells into M1-like macrophages. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-3651] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Introduction: The phosphatidylserine (PS)-targeting antibody, bavituximab, is currently in Phase IIb clinical trials in patients with lung cancer. Bavituximab, and its murine counterpart, 2aG4, induce the attack of monocytes and macrophages on PS-expressing tumor vascular endothelium and tumor cells and inhibit the immunosuppressive effects of PS in the tumor microenvironment. Myeloid-derived suppressor cells (MDSC) are one of the major cells responsible for the immunosuppressed state in tumors. In this study, we tested the influence of 2aG4 on the differentiation of MDSC into M1-like tumor associated macrophages (TAMs). Methods: MDSC were isolated from 4T1 tumor bearing mice with anti-Gr1-coated magnetic beads. The purified MDSC were then cultured for 5 days in the presence of 2aG4 or control C44 antibody. For in vivo studies, PC3 tumor-bearing mice were treated with 2aG4 for 30 days and MDSC and TAMs in tumors and spleens were analyzed by FACS and immunohistochemistry. Results: 2aG4 treatment of purified MDSC switched their cytokine production from an immunosuppressive IL-10-dominated response to a pro-inflammatory IL-12- and TNFα -dominated response. The percentage of Gr1+ cells decreased to 8% in the 2aG4-treated cultures (P<0.0001) but only to 50 – 57% in the PBS and C44-treated cultures. Treatment with 2aG4 induced the differentiation of MDSC into M1-like macrophages that expressed lower CD206 and produced more NO than control cultures. Treatment of mice bearing PC3 prostate tumors with 2aG4 decreased the percentage of MDSC from 7% to 4% (P<0.001) in the tumors and from 28% to 20% (P<0.001) in the spleens. The antibody treatment also increased the ratio of M1 to M2 TAMs in PC3 tumors from 0.7% to 1.4% (P<0.001). Conclusion: Taken together, our results suggest that 2aG4 causes the differentiation of MDSCs into macrophages having an M1-like phenotype. 2aG4 treatment decreased IL-10 production and increased IL-12 and TNFα-production. These results suggest that 2aG4 treatment reactivates innate immunity in tumors.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3651. doi:10.1158/1538-7445.AM2011-3651
Collapse
Affiliation(s)
| | - Dan Ye
- 1UT Southwestern Medical Ctr., Dallas, TX
| | | |
Collapse
|
22
|
Sierko E, Wojtukiewicz MZ, Zimnoch L, Thorpe PE, Brekken RA, Kisiel W. Co-localization of prothrombin fragment F1+2 and VEGF-R2-bound VEGF in human colon cancer. Anticancer Res 2011; 31:843-847. [PMID: 21498704] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND Colon cancer (CC) is frequently complicated by thromboembolic episodes. Thrombin plays a role in angiogenesis and among others induces the synthesis of vascular endothelial growth factor (VEGF) and its receptors (VEGFR-1 and VEGFR-2). The aim of this study was to assess the expression of prothrombin fragment F1+2 (F1+2), a byproduct in thrombin generation (indicating the presence of thrombin), in relation to the presence of VEGFR-2-bound VEGF (VEGF:VEGFR-2), as an indicator of VEGFR-2 activation in human CC tissue. MATERIALS AND METHODS Immunohistochemical ABC and double staining studies were performed using antibodies against F1+2 and VEGF:VEGFR-2 in 59 specimens obtained from CC patients. RESULTS Medium and high expression of both F1+2 and VEGF:VEGF2 in association with CC cells and endothelial cells was demonstrated. Moreover, coexpression of F1+2 and VEGF:VEGFR-2 was observed in the cells. CONCLUSION The results may suggest a possible functional interaction between thrombin and VEGF-R2 stimulation in human CC in vivo.
Collapse
Affiliation(s)
- Ewa Sierko
- Department of Oncology, Medical University, 12 Ogrodowa St., Bialystok, Poland
| | | | | | | | | | | |
Collapse
|
23
|
Ramesh S, Morrell CN, Tarango C, Thomas GD, Yuhanna IS, Girardi G, Herz J, Urbanus RT, de Groot PG, Thorpe PE, Salmon JE, Shaul PW, Mineo C. Antiphospholipid antibodies promote leukocyte-endothelial cell adhesion and thrombosis in mice by antagonizing eNOS via β2GPI and apoER2. J Clin Invest 2010; 121:120-31. [PMID: 21123944 DOI: 10.1172/jci39828] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Accepted: 10/13/2010] [Indexed: 01/13/2023] Open
Abstract
In antiphospholipid syndrome (APS), antiphospholipid antibodies (aPL) binding to β2 glycoprotein I (β2GPI) induce endothelial cell-leukocyte adhesion and thrombus formation via unknown mechanisms. Here we show that in mice both of these processes are caused by the inhibition of eNOS. In studies of cultured human, bovine, and mouse endothelial cells, the promotion of monocyte adhesion by aPL entailed decreased bioavailable NO, and aPL fully antagonized eNOS activation by diverse agonists. Similarly, NO-dependent, acetylcholine-induced increases in carotid vascular conductance were impaired in aPL-treated mice. The inhibition of eNOS was caused by antibody recognition of domain I of β2GPI and β2GPI dimerization, and it was due to attenuated eNOS S1179 phosphorylation mediated by protein phosphatase 2A (PP2A). Furthermore, LDL receptor family member antagonism with receptor-associated protein (RAP) prevented aPL inhibition of eNOS in cell culture, and ApoER2-/- mice were protected from aPL inhibition of eNOS in vivo. Moreover, both aPL-induced increases in leukocyte-endothelial cell adhesion and thrombus formation were absent in eNOS-/- and in ApoER2-/- mice. Thus, aPL-induced leukocyte-endothelial cell adhesion and thrombosis are caused by eNOS antagonism, which is due to impaired S1179 phosphorylation mediated by β2GPI, apoER2, and PP2A. Our results suggest that novel therapies for APS can now be developed targeting these mechanisms.
Collapse
Affiliation(s)
- Sangeetha Ramesh
- Division of Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Affiliation(s)
- Philip E Thorpe
- University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA.
| |
Collapse
|
25
|
Yin Y, Kavlie A, Thorpe PE. Abstract 5330: Phosphatidylserine-targeting antibody enhances survival benefit of androgen deprivation therapy in mice bearing syngeneic prostate cancer. Cancer Res 2010. [DOI: 10.1158/1538-7445.am10-5330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Purpose: Androgen deprivation therapy (ADT) remains the cornerstone treatment for advanced prostate cancer despite being principally palliative in nature. New treatment strategies aimed at enhancing tumor immunogenicity and damaging tumor vasculature could potentially improve prostate cancer response to ADT. We recently showed that targeting phosphatidylserine by antibodies resulting in enhanced tumor immunogenicity and tumor vascular damage. Bavituximab, a chimeric version anti-phosphatidylserine antibody, is being tested in clinic trails for different cancers. Here we tested the hypothesis that the fully human anti-phosphatidylserine antibody 1N11 can enhance the antitumor properties of ADT in prostate cancer
Experimental Design: Efficacy of ADT and 1N11 against prostate cancer was assessed in C57BL/6 mice bearing syngeneic RM1 prostate tumor by using castration and mouse chimeric 1N11(mch1N11). Effects on mouse survival were assessed. In vivo localization of 1N11,effects on immune cell infiltration, vasculature density were also estimated by histology.
Results: Our data showed that castration of RM1 tumor bearing mice increased the percentage of tumor vessels with exposed phosphatidylserine from 60% to 93%. Castration, when combined with mouse chimeric 1N11, led to significant survival befit versus individual treatments. The mean survival time was 16 days with control antibody. The prolongation in survival was 15 days with the combination, as compared with 3 days with mch1N11, 5 days with castration alone. Toxicity to the mice was not observed. A dramatic enhancement of tumor infiltration by a variety of immune cells and disruption of vasculature implied the combination to be more immunostimulatory and antivasculitic.
Conclusion: Combined treatment with 1N11 and ADT improves survival of mice bearing prostate cancer. These results provide the foundation for using ADT plus fully human 1N11, or bavituximab, to treat prostate cancer patients.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5330.
Collapse
Affiliation(s)
- Yi Yin
- 1UT Southwestern Medical Center, Dallas, TX
| | | | | |
Collapse
|
26
|
Stafford JH, Li S, Thorpe PE. Abstract 5232: Phosphatidylethanolamine is a marker of tumor vasculature and can be used as a target for optical imaging. Cancer Res 2010. [DOI: 10.1158/1538-7445.am10-5232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
New imaging agents are needed that home rapidly to tumors and saturate their target molecules with the unbound residue then clearing rapidly from the blood stream. Such agents should enable rapid detection of tumors. We have found that a phosphatidylethanolamine-binding peptide known as duramycin is an effective targeting moiety for construction of tumor-specific imaging agents. Phosphatidylethanolamine (PE) is one of two major phospholipids that present in the inner leaflet of the cell membranes, the other being phosphatidylserine (PS). We have previously demonstrated that oxidative stress conditions within the tumor microenvironment cause PS to flip to the outer leaflet in tumor endothelial cells. The exposed PS provides a highly specific marker of tumor vasculature. Since PE and PS distribution within the membrane is co-regulated, we hypothesized that PE would also be a marker of tumor vasculature. To target exposed PE, we generated several biotinylated duramycin constructs. Biotinylated duramycin bound to PE which became exposed on endothelial cells after they had been subjected to oxidative stresses. When the biotinylated duramycin was injected intravenously into mice bearing different types of tumors it rapidly localized to tumor vasculature and did not bind blood vessels in normal tissues. Next, we conjugated duramycin conjugated to a near-infrared fluophore (IRDye 800CW) and used it for optical imaging of subcutaneous RM-1 prostate tumors in mice. The duramycin-targeted near infrared probe efficiently labeled tumors and did not accumulate in non-target tissues giving clear detection of the tumors. These results show that PE exposure, like PS exposure, is a marker of tumor vasculature in many types of cancer. Duramycin labeled with detectable probes may have broad application in cancer imaging.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5232.
Collapse
Affiliation(s)
| | - Shuzhen Li
- 1UT Southwestern Medical Ctr., Dallas, TX
| | | |
Collapse
|
27
|
Huang X, Ye D, Thorpe PE. Abstract 1919: Phosphatidylserine on dying tumor cells suppresses dendritic cell activation and inhibits tumor immunity: reversal with PS-targeting antibody. Cancer Res 2010. [DOI: 10.1158/1538-7445.am10-1919] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
We recently showed that PS on the surface of apoptotic cancer cells can suppress recognition of tumor antigens by the immune system. It appears from work in several laboratories that dendritic cells (DC) that ingest PS-expressing tumor cells fail to mature in response to external maturation signals. In the present study, we investigated whether masking PS on apoptotic tumor cells with anti-PS antibody (2aG4) can reverse the inhibitory effect of PS on DC. Mouse bone marrow derived DC were cocultured with irradiated (PS-expressing) 4T1 breast tumor cells in the presence or absence of 2aG4. We found that: (i) masking tumor cell PS with 2aG4 increases their phagocytosis by DCs; (ii) masking tumor cell PS with 2aG4 allows DCs to mature and express immunostimulatory molecules (CD40, CD80, CD86 and MHC II); (iii) masking PS with 2aG4 decreases the production of anti-inflammatory cytokines (TGFβ and IL-10) and increases the production of inflammatory cytokines (TNFα, CCL5, IL-1β and IL-6), indicating that PS-blockade polarizes DC towards the immunostimulatory type I phenotype; (iv) immunizing mice with 2aG4-treated irradiated 4T1 cells enhances the immunogenicity of the tumor cells, rendering them resistant to rechallenge with syngeneic viable 4T1 tumor cells. These results have important implications for our understanding of the immunosuppressive effects of PS in cancer and could lead to the development of a novel whole cell cancer vaccine strategy in which PS-blocking is used to enhance immunogenicity.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1919.
Collapse
Affiliation(s)
| | - Dan Ye
- 1UT Southwestern Medical Ctr., Dallas, TX
| | | |
Collapse
|
28
|
Moody MA, Liao HX, Alam SM, Scearce RM, Plonk MK, Kozink DM, Drinker MS, Zhang R, Xia SM, Sutherland LL, Tomaras GD, Giles IP, Kappes JC, Ochsenbauer-Jambor C, Edmonds TG, Soares M, Barbero G, Forthal DN, Landucci G, Chang C, King SW, Kavlie A, Denny TN, Hwang KK, Chen PP, Thorpe PE, Montefiori DC, Haynes BF. Anti-phospholipid human monoclonal antibodies inhibit CCR5-tropic HIV-1 and induce beta-chemokines. ACTA ACUST UNITED AC 2010; 207:763-76. [PMID: 20368576 PMCID: PMC2856026 DOI: 10.1084/jem.20091281] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Traditional antibody-mediated neutralization of HIV-1 infection is thought to result from the binding of antibodies to virions, thus preventing virus entry. However, antibodies that broadly neutralize HIV-1 are rare and are not induced by current vaccines. We report that four human anti-phospholipid monoclonal antibodies (mAbs) (PGN632, P1, IS4, and CL1) inhibit HIV-1 CCR5-tropic (R5) primary isolate infection of peripheral blood mononuclear cells (PBMCs) with 80% inhibitory concentrations of <0.02 to ∼10 µg/ml. Anti-phospholipid mAbs inhibited PBMC HIV-1 infection in vitro by mechanisms involving binding to monocytes and triggering the release of MIP-1α and MIP-1β. The release of these β-chemokines explains both the specificity for R5 HIV-1 and the activity of these mAbs in PBMC cultures containing both primary lymphocytes and monocytes.
Collapse
Affiliation(s)
- M Anthony Moody
- Duke Human Vaccine Institute, Duke University Medical Center, Durham, NC 27710, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Liang Y, Besch-Williford C, Benakanakere I, Thorpe PE, Hyder SM. Targeting mutant p53 protein and the tumor vasculature: an effective combination therapy for advanced breast tumors. Breast Cancer Res Treat 2010; 125:407-20. [PMID: 20349129 DOI: 10.1007/s10549-010-0851-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Accepted: 03/13/2010] [Indexed: 10/19/2022]
Abstract
Breast cancer progression depends upon the elaboration of a vasculature sufficient for the nourishment of the developing tumor. Breast tumor cells frequently contain a mutant form of p53 (mtp53), a protein which promotes their survival. The aim of this study was to determine whether combination therapy targeting mtp53 and anionic phospholipids (AP) on tumor blood vessels might be an effective therapeutic strategy for suppressing advanced breast cancer. We examined the therapeutic effects, singly, or in combination, of p53 reactivation and induction of massive apoptosis (PRIMA-1), which reactivates mtp53 and induces tumor cell apoptosis, and 2aG4, a monoclonal antibody that disrupts tumor vasculature by targeting AP on the surface of tumor endothelial cells and causes antibody-dependent destruction of tumor blood vessels, leading to ischemia and tumor cell death. Xenografts from two tumor cell lines containing mtp53, BT-474 and HCC-1428, were grown in nude mice to provide models of advanced breast tumors. After treatment with PRIMA-1 and/or 2aG4, regressing tumors were analyzed for vascular endothelial growth factor (VEGF) expression, blood vessel loss, and apoptotic markers. Individual drug treatment led to partial suppression of breast cancer progression. In contrast, combined treatment with PRIMA-1 and 2aG4 was extremely effective in suppressing tumor growth in both models and completely eradicated approximately 30% of tumors in the BT-474 model. Importantly, no toxic effects were observed in any treatment group. Mechanistic studies determined that PRIMA-1 reactivated mtp53 and also exposed AP on the surface of tumor cells as determined by enhanced 2aG4 binding. Combination treatment led to significant induction of tumor cell apoptosis, loss of VEGF expression, as well as destruction of tumor blood vessels. Furthermore, combination treatment severely disrupted tumor blood vessel perfusion in both tumor models. The observed in vitro PRIMA-1-induced exposure of tumor epithelial cell AP might provide a target for 2aG4 and contribute to the increased effectiveness of such combination therapy in vivo. We conclude that the combined targeting of mtp53 and the tumor vasculature is a novel effective strategy for combating advanced breast tumors.
Collapse
Affiliation(s)
- Yayun Liang
- Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | | | | | | | | |
Collapse
|
30
|
Mouta-Bellum C, Kirov A, Miceli-Libby L, Mancini ML, Petrova TV, Liaw L, Prudovsky I, Thorpe PE, Miura N, Cantley LC, Alitalo K, Fruman DA, Vary CPH. Organ-specific lymphangiectasia, arrested lymphatic sprouting, and maturation defects resulting from gene-targeting of the PI3K regulatory isoforms p85alpha, p55alpha, and p50alpha. Dev Dyn 2010; 238:2670-9. [PMID: 19705443 DOI: 10.1002/dvdy.22078] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The phosphoinositide 3-kinase (PI3K) family has multiple vascular functions, but the specific regulatory isoform supporting lymphangiogenesis remains unidentified. Here, we report that deletion of the Pik3r1 gene, encoding the regulatory subunits p85alpha, p55alpha, and p50alpha impairs lymphatic sprouting and maturation, and causes abnormal lymphatic morphology, without major impact on blood vessels. Pik3r1 deletion had the most severe consequences among gut and diaphragm lymphatics, which share the retroperitoneal anlage, initially suggesting that the Pik3r1 role in this vasculature is anlage-dependent. However, whereas lymphatic sprouting toward the diaphragm was arrested, lymphatics invaded the gut, where remodeling and valve formation were impaired. Thus, cell-origin fails to explain the phenotype. Only the gut showed lymphangiectasia, lymphatic up-regulation of the transforming growth factor-beta co-receptor endoglin, and reduced levels of mature vascular endothelial growth factor-C protein. Our data suggest that Pik3r1 isoforms are required for distinct steps of embryonic lymphangiogenesis in different organ microenvironments, whereas they are largely dispensable for hemangiogenesis.
Collapse
Affiliation(s)
- Carla Mouta-Bellum
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, Maine, USA
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
31
|
He J, Yin Y, Luster TA, Watkins L, Thorpe PE. Antiphosphatidylserine antibody combined with irradiation damages tumor blood vessels and induces tumor immunity in a rat model of glioblastoma. Clin Cancer Res 2009; 15:6871-80. [PMID: 19887482 DOI: 10.1158/1078-0432.ccr-09-1499] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The vascular targeting antibody bavituximab is being combined with chemotherapy in clinical trials in cancer patients. Bavituximab targets the membrane phospholipid, phosphatidylserine, complexed with beta2-glycoprotein I. Phosphatidylserine is normally intracellular but becomes exposed on the luminal surface of vascular endothelium in tumors. Phosphatidylserine exposure on tumor vessels is increased by chemotherapy and irradiation. Here, we determined whether treatment with the murine equivalent of bavituximab, 2aG4, combined with irradiation can suppress tumor growth in a rat model of glioblastoma. EXPERIMENTAL DESIGN F98 glioma cells were injected into the brains of syngeneic rats where they grow initially as a solid tumor and then infiltrate throughout the brain. Rats with established tumors were treated with 10 Gy whole brain irradiation and 2aG4. RESULTS Combination treatment doubled the median survival time of the rats, and 13% of animals were rendered disease free. Neither treatment given individually was as effective. We identified two mechanisms. First, irradiation induced phosphatidylserine exposure on tumor blood vessels and enhanced antibody-mediated destruction of tumor vasculature by monocytes/macrophages. Second, the antibody treatment induced immunity to F98 tumor cells, which are normally weakly immunogenic. Surviving rats were immune to rechallenge with F98 tumor cells. In vitro, 2aG4 enhanced the ability of dendritic cells (DCs) to generate F98-specific cytotoxic T cells. Phosphatidylserine exposure, which is induced on tumor cells by irradiation, likely suppresses tumor antigen presentation, and 2aG4 blocks this tolerogenic effect. CONCLUSION Bavituximab combined with radiotherapy holds promise as a vascular targeting and immune enhancement strategy for the treatment of human glioblastoma.
Collapse
Affiliation(s)
- Jin He
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA
| | | | | | | | | |
Collapse
|
32
|
Donnini S, Solito R, Monti M, Balduini W, Carloni S, Cimino M, Bampton ETW, Pinon LGP, Nicotera P, Thorpe PE, Ziche M. Prevention of ischemic brain injury by treatment with the membrane penetrating apoptosis inhibitor, TAT-BH4. Cell Cycle 2009; 8:1271-8. [PMID: 19305142 DOI: 10.4161/cc.8.8.8301] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In acute thromboembolic stroke, neurological damage is due to ischemia-induced apoptotic death of neuronal cells and the surrounding vascular network. Here, we demonstrate that the BH4 domain of the anti-apoptotic protein, Bcl-x(L), attached to the membrane transport peptide, TAT, reduces stroke injury after intracerebroventricular infusion into immature rats subjected to carotid artery ligation and additional exposure to hypoxia. The injected TAT-BH4 entered neuron bodies, maintained brain architecture, protected neuronal and endothelial cells from apoptosis and promoted neuronal stem cell recruitment. In vitro, TAT-BH4 enhanced the survival of endothelial cells exposed to H(2)O(2), increased neuronal differentiation, and induced axonal remodelling of adult neuronal stem cells. These findings indicate that TAT-BH4 administration protects against acute hypoxia/ischemia injury in the brain by preventing endothelial and neuron cell apoptosis and by inducing neuronal plasticity.
Collapse
Affiliation(s)
- Sandra Donnini
- Department of Molecular Biology, University of Siena, Via Moro 2, Siena, Italy.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Soares MM, King SW, Thorpe PE. Targeting inside-out phosphatidylserine as a therapeutic strategy for viral diseases. Nat Med 2008; 14:1357-62. [PMID: 19029986 PMCID: PMC2597367 DOI: 10.1038/nm.1885] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Accepted: 09/25/2008] [Indexed: 12/13/2022]
Abstract
Targeting exposed anionic phospholipids on a spectrum of virus-infected cells can protect against lethal virus infections in vivo.
Collapse
|
34
|
Marconescu A, Thorpe PE. Coincident exposure of phosphatidylethanolamine and anionic phospholipids on the surface of irradiated cells. Biochim Biophys Acta 2008; 1778:2217-24. [PMID: 18570887 DOI: 10.1016/j.bbamem.2008.05.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Revised: 05/09/2008] [Accepted: 05/12/2008] [Indexed: 01/03/2023]
Abstract
The major anionic phospholipid, phosphatidylserine (PS), and the neutral phospholipid, phosphatidylethanolamine (PE), are largely confined to the inner leaflet of the plasma membrane bilayer in mammalian cells under normal conditions. This asymmetry is lost when cells undergo apoptosis, become activated, or are exposed to irradiation, reactive oxygen species or certain drugs. It is not known whether exposure of anionic phospholipids (APLs) and PE occurs simultaneously or in the same region of the plasma membrane. Here we examined the coincidence of exposure of APLs and PE on the surface of bovine aortic endothelial cells and NS0 myeloma cells after irradiation. The cells were irradiated (5 Gy) and stained for APLs and PE using liposomes coated with either an Fab' fragment of a PS-binding antibody (bavituximab) or a PE-binding peptide (duramycin). Using live cell imaging and flow cytometry, we showed that irradiation leads to synchronous externalization of APLs and PE. The time course of appearance of APLs and PE on the cell surface was the same and the two phospholipid types remained colocalized over time. Distinct patches double positive for APLs and PE were visible. Larger areas of APLs and PE appeared to have detached from the cytoskeleton to form membrane blebs which protruded and drifted on the cell surface. We conclude that APLs and PE coincidently appear on the external leaflet of the plasma membrane of cells after irradiation. Probably, this is because PE and the major APL, PS, share common regulatory mechanisms of translocation.
Collapse
Affiliation(s)
- Andrei Marconescu
- Department of Pharmacology and Simmons and Hamon Cancer Centers, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA
| | | |
Collapse
|
35
|
Jennewein M, Lewis MA, Zhao D, Tsyganov E, Slavine N, He J, Watkins L, Kodibagkar VD, O'Kelly S, Kulkarni P, Antich PP, Hermanne A, Rösch F, Mason RP, Thorpe PE. Vascular imaging of solid tumors in rats with a radioactive arsenic-labeled antibody that binds exposed phosphatidylserine. Clin Cancer Res 2008; 14:1377-85. [PMID: 18316558 DOI: 10.1158/1078-0432.ccr-07-1516] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE We recently reported that anionic phospholipids, principally phosphatidylserine, become exposed on the external surface of vascular endothelial cells in tumors, probably in response to oxidative stresses present in the tumor microenvironment. In the present study, we tested the hypothesis that a chimeric monoclonal antibody that binds phosphatidylserine could be labeled with radioactive arsenic isotopes and used for molecular imaging of solid tumors in rats. EXPERIMENTAL DESIGN Bavituximab was labeled with (74)As (beta(+), T(1/2) 17.8 days) or (77)As (beta(-), T(1/2) 1.6 days) using a novel procedure. The radionuclides of arsenic were selected because their long half-lives are consistent with the long biological half lives of antibodies in vivo and because their chemistry permits stable attachment to antibodies. The radiolabeled antibodies were tested for the ability to image subcutaneous Dunning prostate R3227-AT1 tumors in rats. RESULTS Clear images of the tumors were obtained using planar gamma-scintigraphy and positron emission tomography. Biodistribution studies confirmed the specific localization of bavituximab to the tumors. The tumor-to-liver ratio 72 h after injection was 22 for bavituximab compared with 1.5 for an isotype-matched control chimeric antibody of irrelevant specificity. Immunohistochemical studies showed that the bavituximab was labeling the tumor vascular endothelium. CONCLUSIONS These results show that radioarsenic-labeled bavituximab has potential as a new tool for imaging the vasculature of solid tumors.
Collapse
Affiliation(s)
- Marc Jennewein
- Institute of Nuclear Chemistry, Johannes Gutenberg-University of Mainz, Mainz, Germany
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
36
|
Affiliation(s)
- M. Melina Soares
- PharmacologyUniversity of Texas Southwestern Medical CenterDallasTX
| | - Susan Mims
- PharmacologyUniversity of Texas Southwestern Medical CenterDallasTX
| | - Gustavo Barbero
- PharmacologyUniversity of Texas Southwestern Medical CenterDallasTX
| | - Shuzhen Li
- PharmacologyUniversity of Texas Southwestern Medical CenterDallasTX
| | - Philip E Thorpe
- PharmacologyUniversity of Texas Southwestern Medical CenterDallasTX
| |
Collapse
|
37
|
He J, Luster TA, Thorpe PE. Radiation-enhanced vascular targeting of human lung cancers in mice with a monoclonal antibody that binds anionic phospholipids. Clin Cancer Res 2007; 13:5211-8. [PMID: 17785577 DOI: 10.1158/1078-0432.ccr-07-0793] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE New treatment strategies aimed at damaging tumor vasculature could potentially improve tumor response to radiation therapy. We recently showed that anionic phospholipids, principally phosphatidylserine, are specifically exposed on the luminal surface of tumor blood vessels. Here we tested the hypothesis that radiation therapy can increase phosphatidylserine exposure on lung tumor vasculature, thereby enhancing the antitumor properties of the anti-phosphatidylserine antibody 2aG4. EXPERIMENTAL DESIGN The therapeutic efficacy of radiation therapy plus 2aG4 was tested in nude mice bearing radiation-resistant A549 human lung tumors. Radiation-induced phosphatidylserine exposure on endothelial cells and A549 tumor cells was analyzed by immunofluoresence staining. The mechanism of the enhanced antitumor effect was examined by histology and antibody-dependent cell-mediated cytotoxicity experiments. RESULTS Focal irradiation of A549 human lung cancer xenografts increased the percentage of tumor vessels with exposed phosphatidylserine from 4% to 26%. Treatment of mice bearing A549 tumors with 2aG4 plus focal radiation therapy inhibited tumor growth by 80% and was superior to radiation therapy or 2aG4 alone (P < 0.01). Combination therapy reduced blood vessel density and enhanced monocyte infiltration into the tumor mass beyond that observed with individual treatments. In vitro, 2aG4 enhanced the ability of macrophages to kill endothelial cells with exposed phosphatidylserine in an Fc'-dependent manner. CONCLUSION These results suggest that 2aG4 enhances the antitumor effects of radiation therapy by increasing antibody-dependent cell-mediated cytotoxicity toward tumor vessels with externalized phosphatidylserine. Bavituximab, a chimeric version of 2aG4 in clinical trials, has the potential to enhance the therapeutic efficacy of radiation therapy in lung cancer patients.
Collapse
Affiliation(s)
- Jin He
- Simmons Comprehensive Cancer Center, Hamon Center for Therapeutic Oncology Research, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-9041, USA
| | | | | |
Collapse
|
38
|
Soares M, Syed S, Barbero G, Thorpe PE. ANTIBODY-MEDIATED TARGETING OF “INSIDE-OUT” ANIONIC PHOSPHOLIPIDS IN VIRAL DISEASE (47.21). The Journal of Immunology 2007. [DOI: 10.4049/jimmunol.178.supp.47.21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Abstract
The anionic phospholipid phosphatidylserine (PS) is found exclusively in the inner leaflet of the plasma membrane of resting mammalian cells. We hypothesized that certain events that occur during virus replication (eg cell activation or membrane rearrangement) would trigger the exposure of anionic phospholipids on the outer surface of virus- infected cells and subsequently on the enveloped viruses that bud out of these virus- infected cells. We further hypothesized that these exposed anionic phospholipids would serve as targets for anti-viral therapy. We demonstrate here that anionic phospholipids become exposed on the enveloped Pichinde Virus (a model virus for Lassa Fever virus, a potential bioterrorism agent) and on Pichinde virus-infected cells. To detect anionic phospholipids, we used a chimeric monoclonal antibody, bavituximab, that binds anionic phospholipids in a B2-glycoprotein I dependent manner. We show that bavituximab treatment is able to cure overt disease in guinea pigs lethally infected with Pichinde virus. Bavituximab treatment reduced the amounts of virus in multiple tissues and caused direct clearance of virus from the blood. Direct clearance of free virus and antibody-dependent cellular cytotoxicity of virus-infected cells appear to be the major mechanisms that contribute to the anti-viral effect of bavituximab. Bavituximab-treated survivors were immune to reinfection. Furthermore, the murine version of bavituximab, 3G4, shows therapeutic efficacy in a lethal murine model for human cytomegalovirus. Our study demonstrates the promise of anionic phospholipids as targets for new broad-spectrum anti-viral drugs.
Collapse
Affiliation(s)
- Melina Soares
- Pharmacology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7.304, MC 9041, Dallas, TX, 75390
| | - Sameer Syed
- Pharmacology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7.304, MC 9041, Dallas, TX, 75390
| | - Gustavo Barbero
- Pharmacology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7.304, MC 9041, Dallas, TX, 75390
| | - Philip E Thorpe
- Pharmacology, University of Texas Southwestern Medical Center, 2201 Inwood Road, NC7.304, MC 9041, Dallas, TX, 75390
| |
Collapse
|
39
|
Cantara S, Thorpe PE, Ziche M, Donnini S. TAT-BH4 counteracts Abeta toxicity on capillary endothelium. FEBS Lett 2007; 581:702-6. [PMID: 17274989 DOI: 10.1016/j.febslet.2007.01.037] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2006] [Revised: 01/10/2007] [Accepted: 01/13/2007] [Indexed: 11/30/2022]
Abstract
Oxidative stress is one of the factor contributing to blood brain barrier degeneration. This phenomenon is observed during pathological conditions such as Alzheimer's disease or cerebral amyloid angiopathy in which brain haemorrhages are very frequent. Both diseases are characterized by beta amyloid peptide deposition either in neurons or in vessels. Oxidative stress leads to impairment of mitochondrial functions and apoptotic cell death subsequent to caspases activation. In this paper we demonstrate that BH4 domain of Bcl-xl administrated to endothelial cells as the conjugated form with TAT peptide, reverts Abeta-induced apoptotic cell death by activating a survival programme which is Akt/endothelial nitric oxide synthase dependent.
Collapse
Affiliation(s)
- S Cantara
- Department Molecular Biology, University of Siena, Via Aldo Moro 2, 53100 Siena, Italy.
| | | | | | | |
Collapse
|
40
|
Mohamedali KA, Poblenz AT, Sikes CR, Navone NM, Thorpe PE, Darnay BG, Rosenblum MG. Inhibition of Prostate Tumor Growth and Bone Remodeling by the Vascular Targeting Agent VEGF121/rGel. Cancer Res 2006; 66:10919-28. [PMID: 17108129 DOI: 10.1158/0008-5472.can-06-0459] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The pathophysiology of tumor growth following skeletal metastases and the poor response of this type of lesion to therapeutic intervention remains incompletely understood. Vascular endothelial growth factor (VEGF)-A and its receptors play a role in both osteoclastogenesis and tumor growth. Systemic (i.v.) treatment of nude mice bearing intrafemoral prostate (PC-3) tumors with the vascular ablative agent VEGF(121)/recombinant gelonin (rGel) strongly inhibited tumor growth. Fifty percent of treated animals had complete regression of bone tumors with no development of lytic bone lesions. Immunohistochemical analysis showed that VEGF(121)/rGel treatment suppressed tumor-mediated osteoclastogenesis in vivo. In vitro treatment of murine osteoclast precursors, both cell line (RAW264.7) and bone marrow-derived monocytes (BMM), revealed that VEGF(121)/rGel was selectively cytotoxic to osteoclast precursor cells rather than mature osteoclasts. VEGF(121)/rGel cytotoxicity was mediated by Flt-1, which was down-regulated during osteoclast differentiation. Analysis by flow cytometry and reverse transcription-PCR showed that both BMM and RAW264.7 cells display high levels of Flt-1 but low levels of Flk-1. Internalization of VEGF(121)/rGel into osteoclast precursor cells was suppressed by pretreatment with an Flt-1 neutralizing antibody or by placenta growth factor but not with an Flk-1 neutralizing antibody. Thus, VEGF(121)/rGel inhibits osteoclast maturation in vivo and it seems that this process is important in the resulting suppression of skeletal osteolytic lesions. This is a novel and unique mechanism of action for this class of agents and suggests a potentially new approach for treatment or prevention of tumor growth in bone.
Collapse
Affiliation(s)
- Khalid A Mohamedali
- Department of Experimental Therapeutics and Genitourinary Medical Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | | | | | | | | | | | | |
Collapse
|
41
|
Luster TA, He J, Huang X, Maiti SN, Schroit AJ, de Groot PG, Thorpe PE. Plasma protein beta-2-glycoprotein 1 mediates interaction between the anti-tumor monoclonal antibody 3G4 and anionic phospholipids on endothelial cells. J Biol Chem 2006; 281:29863-71. [PMID: 16905548 DOI: 10.1074/jbc.m605252200] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A promising target on tumor vasculature is phosphatidylserine (PS), an anionic phospholipid that resides exclusively on the inner leaflet of the plasma membrane of resting mammalian cells. We have shown previously that PS becomes exposed on the surface of endothelial cells (EC) in solid tumors. To target PS on tumor vasculature, the murine monoclonal antibody 3G4 was developed. 3G4 localizes to tumor vasculature, inhibits tumor growth, and enhances anti-tumor chemotherapies without toxicity in mice. A chimeric version of 3G4 is in clinical trials. In this study, we investigated the basis for the interaction between 3G4 and EC with surface-exposed PS. We demonstrate that antibody binding to PS is dependent on plasma protein beta-2-glycoprotein 1 (beta2GP1). beta2GP1 is a 50-kDa glycoprotein that binds weakly to anionic phospholipids under physiological conditions. We show that 3G4 enhances binding of beta2GP1 to EC induced to expose PS. We also show that divalent 3G4-beta2GP1 complexes are required for enhanced binding, since 3G4 Fab' fragments do not bind EC with exposed PS. Finally, we demonstrate that an artificial dimeric beta2GP1 construct binds to EC with exposed PS in the absence of 3G4, confirming that antibody binding is mediated by dimerization of beta2GP1. Together, these data indicate that 3G4 targets tumor EC by increasing the avidity of beta2GP1 for anionic phospholipids through formation of multivalent 3G4-beta2GP1 complexes.
Collapse
MESH Headings
- Animals
- Antibodies, Monoclonal/metabolism
- Antibodies, Monoclonal/therapeutic use
- Antineoplastic Agents/metabolism
- Antineoplastic Agents/therapeutic use
- Binding Sites, Antibody
- Cattle
- Cells, Cultured
- Drug Evaluation, Preclinical
- Endothelium, Vascular/immunology
- Endothelium, Vascular/metabolism
- Endothelium, Vascular/pathology
- Growth Inhibitors/metabolism
- Growth Inhibitors/therapeutic use
- Humans
- Mice
- Neoplasms, Experimental/blood supply
- Neoplasms, Experimental/immunology
- Neoplasms, Experimental/metabolism
- Neoplasms, Experimental/pathology
- Phosphatidylserines/immunology
- Phosphatidylserines/metabolism
- beta 2-Glycoprotein I/blood
- beta 2-Glycoprotein I/physiology
Collapse
Affiliation(s)
- Troy A Luster
- Simmons Comprehensive Cancer Center, Hamon Center for Therapeutic Oncology Research, the Department of Pharmacology and the Department of Radiation Oncology, the University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | | | | | | | | | | | | |
Collapse
|
42
|
Beck AW, Luster TA, Miller AF, Holloway SE, Conner CR, Barnett CC, Thorpe PE, Fleming JB, Brekken RA. Combination of a monoclonal anti-phosphatidylserine antibody with gemcitabine strongly inhibits the growth and metastasis of orthotopic pancreatic tumors in mice. Int J Cancer 2006; 118:2639-43. [PMID: 16353142 DOI: 10.1002/ijc.21684] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Pancreatic cancer continues to have a dismal prognosis and novel therapy is needed. In this study, we evaluate a promising new target for therapy, phosphatidylserine (PS). PS is an anionic phospholipid located normally on the inner leaflet of the plasma membrane in mammalian cells. In the tumor microenvironment, PS becomes externalized on vascular endothelium. The monoclonal antibody 3G4 binds PS and promotes an inflammatory response against tumor blood vessels, resulting in reduction of tumor growth. Mice with orthotopic pancreatic tumors were treated with 3G4, gemcitabine or a combination of both drugs. Tumor burden including pancreas weight and metastatic lesions (liver, lymph node and peritoneal) were reduced 3- to 5-fold by the combination therapy as compared with 1.5- to 2-fold with 3G4 and gemcitabine alone, respectively. Treatment of tumor-bearing animals with the combination therapy increased macrophage infiltration into the tumor mass 10-fold and reduced microvessel density in the tumor by 2.5-fold compared with tumors from untreated animals. Gemcitabine alone and 3G4 alone were less effective than the combination of the 2 agents together. The additive therapeutic effect of both agents appears to be because chemotherapy increases PS exposure on tumor vascular endothelium and amplifies the target for attack by 3G4. In conclusion, 3G4 enhanced the anti-tumor and anti-metastatic activity of gemcitabine without contributing to toxicity.
Collapse
Affiliation(s)
- Adam W Beck
- Simmons Comprehensive Cancer Center and Hamon Center for Therapeutic Oncology Research, University of Texas Southwestern Medical Center, Dallas, TX 75390-8593, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
43
|
Mohamedali KA, Kedar D, Sweeney P, Kamat A, Davis DW, Eve BY, Huang S, Thorpe PE, Dinney CP, Rosenblum MG. The vascular-targeting fusion toxin VEGF121/rGel inhibits the growth of orthotopic human bladder carcinoma tumors. Neoplasia 2006; 7:912-20. [PMID: 16242074 PMCID: PMC1550288 DOI: 10.1593/neo.05292] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2005] [Revised: 07/25/2005] [Accepted: 07/25/2005] [Indexed: 01/11/2023] Open
Abstract
Vascular endothelial growth factor (VEGF) and its receptors (FLT-1 and KDR) are overexpressed by human bladder cancer cells and tumor endothelial cells, respectively. Strategies that target VEGF receptors hold promise as antiangiogenic therapeutic approaches to bladder cancer. A fusion protein of VEGF121 and the plant toxin gelonin (rGel) was constructed, expressed in bacteria, and purified to homogeneity. Cytotoxicity experiments of VEGF121/rGel on the highly metastatic 253J B-V human bladder cancer cell line demonstrated that the VEGF121/rGel does not specifically target these cells, whereas Western blot analysis showed no detectable expression of KDR. Treatment with VEGF121/rGel against orthotopically implanted 253J B-V xenografts in nude mice resulted in a significant suppression of bladder tumor growth (approximately 60% inhibition; P < .05) compared to controls. Immunohistochemistry studies of orthotopic 253J B-V tumors demonstrated that KDR is highly overexpressed in tumor vasculature. Immunofluorescence staining with antibodies to CD-31 (blood vessel endothelium) and rGel demonstrated a dramatic colocalization of the construct on tumor neovasculature. Treated tumors also displayed an increase in terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling staining compared to controls. Thus, VEGF121/rGel inhibits the growth of human bladder cancer by cytotoxic effects directed against the tumor vascular supply and has significant potential as a novel antiangiogenic therapeutic against human bladder cancer.
Collapse
Affiliation(s)
- Khalid A Mohamedali
- Department of Experimental Therapeutics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Ran S, Mohamedali KA, Luster TA, Thorpe PE, Rosenblum MG. The vascular-ablative agent VEGF(121)/rGel inhibits pulmonary metastases of MDA-MB-231 breast tumors. Neoplasia 2005; 7:486-96. [PMID: 15967101 PMCID: PMC1501168 DOI: 10.1593/neo.04631] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2004] [Revised: 12/03/2004] [Accepted: 12/07/2004] [Indexed: 11/18/2022] Open
Abstract
VEGF(121)/rGel, a fusion protein composed of the growth factor VEGF(121) and the recombinant toxin gelonin (rGel), targets the tumor neovasculature and exerts impressive cytotoxic effects by inhibiting protein synthesis. We evaluated the effect of VEGF(121)/rGel on the growth of metastatic MDA-MB-231 tumor cells in SCID mice. VEGF(121)/rGel treatment reduced surface lung tumor foci by 58% compared to controls (means were 22.4 and 53.3, respectively; P < .05) and the mean area of lung colonies by 50% (210 +/- 37 m(2) vs 415 +/- 10 m(2) for VEGF(121)/rGel and control, respectively; P < .01). In addition, the vascularity of metastatic foci was significantly reduced (198 +/- 37 vs 388 +/- 21 vessels/mm(2) for treated and control, respectively). Approximately 62% of metastatic colonies from the VEGF(121)/rGel-treated group had fewer than 10 vessels per colony compared to 23% in the control group. The VEGF receptor Flk-1 was intensely detected on the metastatic vessels in the control but not in the VEGF(121)/rGel-treated group. Metastatic foci present in lungs had a three-fold lower Ki-67 labeling index compared to control tumors. Thus, the antitumor vascular-ablative effect of VEGF(121)/rGel may be utilized not only for treating primary tumors but also for inhibiting metastatic spread and vascularization of metastases.
Collapse
Affiliation(s)
- Sophia Ran
- Simmons Comprehensive Cancer Center and Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | | | | | | | | |
Collapse
|
45
|
Jennewein M, Qaim SM, Hermanne A, Jahn M, Tsyganov E, Slavine N, Seliounine S, Antich PA, Kulkarni PV, Thorpe PE, Mason RP, Rösch F. A new method for radiochemical separation of arsenic from irradiated germanium oxide. Appl Radiat Isot 2005; 63:343-51. [PMID: 15955705 DOI: 10.1016/j.apradiso.2005.04.005] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2005] [Revised: 04/04/2005] [Accepted: 04/13/2005] [Indexed: 11/30/2022]
Abstract
Radioarsenic labelled radiopharmaceuticals could be a valuable asset to Positron Emission Tomography (PET). In particular, the long half-lives of (72)As (T(1/2)=26 h) and (74)As (T(1/2)=17.8 d) allow to investigate slow physiological or metabolical processes, like the enrichment and distribution of antibodies in tumor tissue. This work describes the direct production of no-carrier-added (nca) arsenic isotopes *As, with *=71, 72, 73, 74 or 77, the reaction to [*As]AsI(3) and its radiochemical separation from the irradiated solid germanium oxide via polystyrene-based solid-phase extraction. The germanium oxide target, irradiated at a cyclotron or a nuclear reactor, is dissolved in concentrated HF and Ge is separated almost quantitatively (99.97%) as [GeF(6)](2-). [*As]AsI(3) is formed by addition of potassium iodide. The radiochemical separation yield for arsenic is >90%. [*As]AsI(3) is a versatile radioarsenic labelling synthon.
Collapse
Affiliation(s)
- M Jennewein
- Institute of Nuclear Chemistry, Johannes Gutenberg University of Mainz, Fritz-Strassmann-Weg 2, 55128 Mainz, Germany
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
46
|
Ran S, He J, Huang X, Soares M, Scothorn D, Thorpe PE. Antitumor effects of a monoclonal antibody that binds anionic phospholipids on the surface of tumor blood vessels in mice. Clin Cancer Res 2005; 11:1551-62. [PMID: 15746060 DOI: 10.1158/1078-0432.ccr-04-1645] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE We recently reported that anionic phospholipids, principally phosphatidylserine, become exposed on the external surface of viable vascular endothelial cells in tumors, possibly in response to oxidative stresses present in the tumor microenvironment. In the present study, we tested the hypothesis that a monoclonal antibody directed against anionic phospholipids might exert antitumor effects by causing vascular damage in tumors. EXPERIMENTAL DESIGN A new mouse immunoglobulin G3 monoclonal antibody, 3G4, was raised that binds anionic phospholipids in the presence of serum or beta2-glycoprotein I. The antibody was tested for its ability to localize to tumor vessels and exert antitumor effects in mice. RESULTS 3G4 recognized anionic phospholipids on the external membrane of H(2)O(2)-treated endothelial cells and in vitro. It localized specifically to tumor vascular endothelium and to necrotic tumor cells after injection into severe combined immunodeficient mice bearing orthotopic MDA-MB-435 tumors. Treatment with 3G4 retarded the growth of four different tumors in mice. It reduced the growth of established orthotopic MDA-MB-231 and MDA-MB-435 human breast tumors in mice by 75% and 65% respectively, large L540 human Hodgkin's tumors by 50%, and small syngeneic Meth A fibrosarcomas by 90%. Histologic examination revealed vascular damage, a reduction in vascular density, and a reduction in tumor plasma volume. Treatment with 3G4 induced the binding of monocytes to tumor endothelium and infiltration of macrophages into MDA-MB-435 and MDA-MB-231 tumors. No toxicity to the mice was observed. CONCLUSIONS 3G4 localizes specifically to complexes of anionic phospholipids and serum proteins on the surface of vascular endothelial cells in tumors in mice. This results in damage to tumor vasculature and suppression of tumor growth.
Collapse
Affiliation(s)
- Sophia Ran
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 2201 Inwood Road NC7.304, Dallas, TX 75390, USA
| | | | | | | | | | | |
Collapse
|
47
|
Huang X, Bennett M, Thorpe PE. A monoclonal antibody that binds anionic phospholipids on tumor blood vessels enhances the antitumor effect of docetaxel on human breast tumors in mice. Cancer Res 2005; 65:4408-16. [PMID: 15899833 DOI: 10.1158/0008-5472.can-05-0031] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Anionic phospholipids, principally phosphatidylserine, become exposed on the external surface of viable vascular endothelial cells in tumors, providing an excellent marker for tumor vascular targeting. We recently raised an IgG monoclonal antibody, 3G4, which binds to anionic phospholipids in a beta2-glycoprotein I-dependent manner. It inhibited tumor growth in a variety of rodent tumor models by stimulating antibody-dependent cellular cytotoxicity toward tumor vessels. In the present study, we tested the hypothesis that docetaxel, which is known to have antivascular effects on tumors, might induce exposure of anionic phospholipids on tumor vasculature and, thus, enhance the antitumor activity of 3G4. Treatment of human umbilical vascular endothelial cells with subtoxic concentrations of docetaxel (20 pmol/L) in vitro caused anionic phospholipids to be externalized without inducing apoptosis. Docetaxel treatment of mice increased the percentage of tumor vessels that expose anionic phospholipids from 35% to 60%. No induction of phosphatidylserine was observed on vessels in normal tissues even after systemic treatment with docetaxel. Treatment of mice bearing orthotopic MDA-MB-435 human breast tumors with 3G4 plus docetaxel inhibited tumor growth by 93%. Treatment of mice bearing disseminated MDA-MB-435 tumors with 3G4 plus docetaxel reduced the average number of tumor colonies in the lungs by 93% and half the animals did not develop tumors. In both tumor models, the antitumor effect of the combination was statistically superior (P < 0.01) to that of docetaxel or 3G4 alone. Combination therapy reduced the tumor vessel density and plasma volume in tumors to a greater extent than did the individual drugs. The combination therapy was no more toxic to the mice than was docetaxel alone. These results indicate that, as an adjuvant therapy, 3G4 could enhance the therapeutic efficacy of docetaxel in breast cancer patients.
Collapse
Affiliation(s)
- Xianming Huang
- Department of Pharmacology and Simmons and Hamon Cancer Centers, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas 75390-8594, USA
| | | | | |
Collapse
|
48
|
Stephan S, Datta K, Wang E, Li J, Brekken RA, Parangi S, Thorpe PE, Mukhopadhyay D. Effect of rapamycin alone and in combination with antiangiogenesis therapy in an orthotopic model of human pancreatic cancer. Clin Cancer Res 2005; 10:6993-7000. [PMID: 15501979 DOI: 10.1158/1078-0432.ccr-04-0808] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE The overall 5-year survival of patients with pancreatic cancer remains <5%. Novel therapeutic strategies are needed. We examined the effect of rapamycin, alone and in combination with antiangiogenesis therapy, on pancreatic cancer in vivo. EXPERIMENTAL DESIGN Human pancreatic cancer AsPC-1 cells were orthotopically injected into severe combined immunodeficient/beige mice to evaluate primary tumor growth and liver metastasis after treatment with rapamycin alone or in combination with anti-vascular endothelial growth factor antibody 2C3. Tumor cell proliferation was determined by bromodeoxyuridine incorporation. To detect tumor cell apoptosis, the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay was used. Tumor angiogenesis was investigated by using a monoclonal anti-CD31 antibody. All statistical tests were two-sided. RESULTS Rapamycin, alone and in combination with 2C3, strongly inhibited primary and metastatic tumor growth in an orthotopic pancreatic cancer animal model. Furthermore, the combination therapy significantly improved the effect on liver metastasis compared with single treatment with either rapamycin (P = 0.0128) or 2C3 (P = 0.0099). Rapamycin alone inhibited pancreatic tumor cell proliferation, induced apoptosis, and decreased tumor angiogenesis. Nevertheless, the combination therapy showed a significant, stronger inhibition of tumor cell proliferation (P = 0.0002 versus rapamycin alone and P < 0.0001 versus 2C3 alone). The induction of apoptosis was significantly higher than in the rapamycin-treated group (P = 0.0039). Additionally, the combination therapy further improved suppression of tumor cell angiogenesis compared with rapamycin treatment (P = 0.029) CONCLUSIONS Our studies propose new therapeutic strategies to inhibit both primary and metastatic tumor growth in pancreatic cancer. Considering the fact that liver metastasis is a crucial problem in advanced stages of pancreatic cancer, the combination therapy of rapamycin plus anti-vascular endothelial growth factor antibody 2C3 is a significant advantage compared with single treatment with rapamycin.
Collapse
Affiliation(s)
- Susann Stephan
- Department of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts, USA
| | | | | | | | | | | | | | | |
Collapse
|
49
|
Abstract
Vascular targeting agents (VTAs) for the treatment of cancer are designed to cause a rapid and selective shutdown of the blood vessels of tumors. Unlike antiangiogenic drugs that inhibit the formation of new vessels, VTAs occlude the pre-existing blood vessels of tumors to cause tumor cell death from ischemia and extensive hemorrhagic necrosis. Tumor selectivity is conferred by differences in the pathophysiology of tumor versus normal tissue vessels (e.g., increased proliferation and fragility, and up-regulated proteins). VTAs can kill indirectly the tumor cells that are resistant to conventional antiproliferative cancer therapies, i.e., cells in areas distant from blood vessels where drug penetration is poor, and hypoxia can lead to radiation and drug resistance. VTAs are expected to show the greatest therapeutic benefit as part of combined modality regimens. Preclinical studies have shown VTA-induced enhancement of the effects of conventional chemotherapeutic agents, radiation, hyperthermia, radioimmunotherapy, and antiangiogenic agents. There are broadly two types of VTAs, small molecules and ligand-based, which are grouped together, because they both cause acute vascular shutdown in tumors leading to massive necrosis. The small molecules include the microtubulin destabilizing drugs, combretastatin A-4 disodium phosphate, ZD6126, AVE8062, and Oxi 4503, and the flavonoid, DMXAA. Ligand-based VTAs use antibodies, peptides, or growth factors that bind selectively to tumor versus normal vessels to target tumors with agents that occlude blood vessels. The ligand-based VTAs include fusion proteins (e.g., vascular endothelial growth factor linked to the plant toxin gelonin), immunotoxins (e.g., monoclonal antibodies to endoglin conjugated to ricin A), antibodies linked to cytokines, liposomally encapsulated drugs, and gene therapy approaches. Combretastatin A-4 disodium phosphate, ZD6126, AVE8062, and DMXAA are undergoing clinical evaluation. Phase I monotherapy studies have shown that the agents are tolerated with some demonstration of single agent efficacy. Because efficacy is expected when the agents are used with conventional chemotherapeutic drugs or radiation, the results of Phase II combination studies are eagerly awaited.
Collapse
Affiliation(s)
- Philip E Thorpe
- Department of Pharmacology and Simmons Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA.
| |
Collapse
|
50
|
Huang X, Bennett M, Thorpe PE. Anti-tumor effects and lack of side effects in mice of an immunotoxin directed against human and mouse prostate-specific membrane antigen. Prostate 2004; 61:1-11. [PMID: 15287089 DOI: 10.1002/pros.20074] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND Prostate-specific membrane antigen (PSMA) is a transmembrane protein that is largely restricted to prostatic epithelial cells in humans and is strongly upregulated on prostatic carcinoma cells. It is also expressed on the endothelium of tumor vasculature in humans, but not on the vasculature of normal tissues. Expression of low levels of PSMA has also been found on non-vascular cells in several normal tissues, most prominently on the brain and kidney in humans. PSMA is an excellent candidate for targeting prostate cancer or targeting tumor vasculature of various solid tumors. The high potential clinical benefit of these agents has prompted the search for an animal model in which to assess the efficacy and safety of anti-PSMA monoclonal antibody (mAb)-based therapies. METHODS A rat monoclonal antibody, E6 that recognizes both mouse and human PSMA was generated using conventional hybridoma techniques. The antibody was characterized by enzyme-linked immunosorbent assay (ELISA), Western blot, and immunohistochemistry. An immunotoxin composed of E6, antibody and deglycosylated ricin A-chain (dgA) was prepared chemically. The anti-tumor effects of the immunotoxin were determined in vitro and in mice bearing subcutaneous LnCaP human prostate tumors, which express PSMA on the tumor cell surface. RESULTS E6 recognizes the extracellular domain of both human and mouse PSMA in ELISA, immunoblot and by immunohistochemistry. E6 strongly stained the vascular endothelium of tumors from humans but not from mice. E6 stained proximal tubules in mouse and human kidneys, and neurons in the mouse and human hippocampus but, unlike the human, did not detectably stain epithelial cells in mouse prostate or small intestine. An E6-dgA immunoconjugate strongly inhibited the growth of LnCaP tumor xenografts without causing apparent toxicity to the mice. Histological observation indicated that the anti-tumor effects were mediated through direct cytotoxic effects on the tumor cells. CONCLUSIONS We have generated and characterized a rat mAb (E6) that reacts specifically with both human and mouse PSMA and have demonstrated that an immunotoxin constructed from E6 is safe and effective against human prostatic carcinoma cells growing subcutaneously in nude mice.
Collapse
Affiliation(s)
- Xianming Huang
- Simmons Comprehensive Cancer Center, UT Southwestern Medical Center, 2201 Inwood, Road, Dallas, Texas, USA
| | | | | |
Collapse
|