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Updated: Jan 26, 2026
Generation of Monoclonal Antibodies Against Natural Products
Published on: April 6, 2019
Development of a Cross-Reactive Monoclonal Antibody for Detecting the Tumor Stroma
Hallie M Hintz1, Aidan E Cowan1, Mariya Shapovalova1
1Department of Pharmacology , University of Minnesota Medical School , Minneapolis , Minnesota 55455 , United States.
Abstract:
Here, we document the discovery of a monoclonal antibody that selectively binds to both human and murine fibroblast activation protein alpha (FAP), a serine protease that is overexpressed on cancer-associated fibroblasts (CAFs), making it an attractive therapeutic target for the aiding and abetting tumor microenvironment. The lead antibody, B12, was identified from a naïve murine single-chain variable fragment antibody phage display library screened against recombinant human FAP on magnetic beads. The heavy and light chains of B12 were cloned into full-length human immunoglobulin 1 (IgG) vectors and expressed as a chimeric monoclonal antibody (B12 IgG). We engineered a drug-resistant prostate cancer cell line, CWR-R1-EnzR, to express human FAP for antibody characterization and validation (R1-EnzRFAP). B12 IgG selectively bound to the R1-EnzRFAP cells by flow cytometry and was internalized in vitro by confocal microscopy. B12 IgG was further evaluated as a near-infrared (NIR) optical imaging probe in R1-EnzRFAP and parental xenograft models. High tumor uptake and retention of the NIR probe was observed in the R1-EnzRFAP xenografts, and endogenous expression of murine stromal origin FAP was detected in the parental xenografts. Ex vivo evaluation of these models by immunohistochemistry documented B12 IgG localization to both human and murine FAP-expressing cells.
Insights
Researchers discovered a novel monoclonal antibody, B12 IgG, that targets fibroblast activation protein alpha (FAP). This antibody shows promise for cancer therapy by binding to FAP-overexpressing cells in the tumor microenvironment.
Area of Science:
- Immunology
- Oncology
- Biochemistry
Background:
- Fibroblast activation protein alpha (FAP) is a serine protease overexpressed on cancer-associated fibroblasts (CAFs).
- FAP is a promising therapeutic target within the tumor microenvironment.
- Targeting FAP can aid in cancer treatment strategies.
Purpose of the Study:
- To discover and characterize a monoclonal antibody that selectively binds to human and murine FAP.
- To evaluate the antibody's potential as a diagnostic and therapeutic agent.
Main Methods:
- A phage display library was screened to identify the lead antibody, B12.
- B12 was engineered into a full-length human IgG (B12 IgG).
- Antibody binding and internalization were assessed using flow cytometry and confocal microscopy in engineered cancer cell lines (R1-EnzRFAP).
- Near-infrared (NIR) optical imaging was performed in xenograft models.
Main Results:
- B12 IgG demonstrated selective binding and internalization in FAP-expressing cells.
- NIR-labeled B12 IgG showed high tumor uptake and retention in R1-EnzRFAP xenografts.
- Immunohistochemistry confirmed B12 IgG localization to both human and murine FAP-expressing cells in vivo.
Conclusions:
- The monoclonal antibody B12 IgG selectively targets both human and murine FAP.
- B12 IgG is a viable candidate for developing targeted cancer therapies and imaging agents.
- This antibody facilitates the study and targeting of FAP in the tumor microenvironment.
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