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Updated: Jun 15, 2026
Oncogenic Gene Fusion Detection Using Anchored Multiplex Polymerase Chain Reaction Followed by Next Generation Sequencing
Published on: July 5, 2019
Development of FAP-targeted theranostics discovered by next-generation sequencing-augmented mining of a novel
Gihan S Gunaratne1, Joseph P Gallant1, Kendahl L Ott1,2
1Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI 53705, USA.
Abstract:
Cancer-associated fibroblasts (CAFs) in the stroma of solid tumors promote an immunosuppressive tumor microenvironment (TME) that drives resistance to therapies. The expression of the protease fibroblast activation protein (FAP) on the surface of CAFs has made FAP a target for development of therapies to dampen immunosuppression. Relatively few biologics have been developed for FAP and none have been developed that exploit the unique engagement properties of Variable New Antigen Receptors (VNARs) from shark antibodies. As the smallest binding domain in nature, VNARs cleverage unique geometries and recognize epitopes conventional antibodies cannot. By directly immunizing a nurse shark with FAP, we created a large anti-FAP VNAR phage display library. This library allowed us to identify a suite of anti-FAP VNARs through traditional biopanning and also by an in silico approach that did not require any prior affinity-based enrichment in vitro. We investigated four VNAR-Fc fusion proteins for theranostic properties and found that all four recognized FAP with high affinity and were rapidly internalized by FAP-positive cells. As a result, the VNAR-Fc constructs were effective antibody-drug conjugates in vitro and were able to localize to FAP-positive xenografts in vivo. Our findings establish VNAR-Fc constructs as a versatile platform for theranostic development that could yield innovative cancer therapies targeting the TME.
Insights
Shark antibody fragments (VNARs) targeting fibroblast activation protein (FAP) show promise for cancer therapy. These novel VNAR-Fc constructs effectively target FAP-positive tumors and offer a new platform for theranostic development.
Area of Science:
- Oncology
- Immunology
- Biotechnology
Background:
- Cancer-associated fibroblasts (CAFs) create an immunosuppressive tumor microenvironment (TME) that hinders cancer therapies.
- Fibroblast activation protein (FAP) expressed by CAFs is a therapeutic target for modulating the TME.
- Existing FAP-targeting biologics do not leverage the unique properties of Variable New Antigen Receptors (VNARs).
Purpose of the Study:
- To develop novel anti-FAP VNARs using shark antibody technology.
- To evaluate the theranostic potential of VNAR-Fc fusion proteins targeting FAP.
- To establish VNAR-Fc constructs as a versatile platform for cancer theranostics.
Main Methods:
- Generated an anti-FAP VNAR phage display library by immunizing a nurse shark.
- Identified anti-FAP VNARs through in vitro biopanning and in silico methods.
- Investigated four VNAR-Fc fusion proteins for FAP binding, internalization, and in vivo tumor localization.
Main Results:
- Developed a large library of anti-FAP VNARs.
- Identified VNARs with high affinity for FAP.
- VNAR-Fc constructs demonstrated effective FAP targeting, rapid internalization by FAP-positive cells, and in vitro antibody-drug conjugate activity.
- VNAR-Fc constructs localized to FAP-positive xenografts in vivo.
Conclusions:
- VNAR-Fc fusion proteins are effective theranostic agents targeting FAP.
- VNAR technology offers a novel approach for developing targeted cancer therapies and diagnostics.
- VNAR-Fc constructs represent a versatile platform for modulating the tumor microenvironment and improving therapeutic outcomes.
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