Development of a Function-Blocking Antibody Against Fibulin-3 as a Targeted Reagent for Glioblastoma.

Abstract

Purpose: We sought a novel approach against glioblastomas (GBM) focused on targeting signaling molecules localized in the tumor extracellular matrix (ECM). We investigated fibulin-3, a glycoprotein that forms the ECM scaffold of GBMs and promotes tumor progression by driving Notch and NFκB signaling.Experimental Design: We used deletion constructs to identify a key signaling motif of fibulin-3. An mAb (mAb428.2) was generated against this epitope and extensively validated for specific detection of human fibulin-3. mAb428.2 was tested in cultures to measure its inhibitory effect on fibulin-3 signaling. Nude mice carrying subcutaneous and intracranial GBM xenografts were treated with the maximum achievable dose of mAb428.2 to measure target engagement and antitumor efficacy.Results: We identified a critical 23-amino acid sequence of fibulin-3 that activates its signaling mechanisms. mAb428.2 binds to that epitope with nanomolar affinity and blocks the ability of fibulin-3 to activate ADAM17, Notch, and NFκB signaling in GBM cells. mAb428.2 treatment of subcutaneous GBM xenografts inhibited fibulin-3, increased tumor cell apoptosis, and enhanced the infiltration of inflammatory macrophages. The antibody reduced tumor growth and extended survival of mice carrying GBMs as well as other fibulin-3-expressing tumors. Locally infused mAb428.2 showed efficacy against intracranial GBMs, increasing tumor apoptosis and reducing tumor invasion and vascularization, which are enhanced by fibulin-3.Conclusions: To our knowledge, this is the first rationally developed, function-blocking antibody against an ECM target in GBM. Our results offer a proof of principle for using "anti-ECM" strategies toward more efficient targeted therapies for malignant glioma. Clin Cancer Res; 24(4); 821-33. ©2017 AACR.

• Authors: Mohan S Nandhu, Prajna Behera, Vivek Bhaskaran, Sharon L Longo, Lina M Barrera-Arenas, Sadhak Sengupta, Diego J Rodriguez-Gil, E Antonio Chiocca, Mariano S Viapiano
• Journal: Clinical cancer research : an official journal of the American Association for Cancer Research (Clin Cancer Res) Vol. 24 Issue 4 Pg. 821-833 (02 15 2018) ISSN: 1557-3265 [Electronic] United States
• PMID: 29146721 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: ©2017 American Association for Cancer Research.

Chemical References

• Antibodies, Blocking
• EFEMP1 protein, human
• Extracellular Matrix Proteins

Topics

• Amino Acid Sequence
• Animals
• Antibodies, Blocking (immunology, pharmacology)
• Apoptosis (drug effects)
• Brain Neoplasms (drug therapy, genetics, metabolism)
• Cell Line, Tumor
• Extracellular Matrix Proteins (antagonists & inhibitors, genetics, immunology)
• Glioblastoma (drug therapy, metabolism)
• HEK293 Cells
• Humans
• Mice, Inbred C57BL
• Mice, Nude
• Molecular Targeted Therapy (methods)
• Sequence Homology, Amino Acid
• Signal Transduction (drug effects)
• Survival Analysis
• Tumor Burden (drug effects)
• Xenograft Model Antitumor Assays