Development of a cross-reactive monoclonal antibody for detecting the tumor stroma

Hallie M. Hintz, Aidan E. Cowan, Mariya Shapovalova, Aaron LeBeau

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1466-1476
Number of pages11
JournalBioconjugate Chemistry
Issue number5
StatePublished - May 15 2019

Bibliographical note

Funding Information:
This work was funded by a Prostate Cancer Foundation Young Investigator Award (A.M.L.), Mayo Clinic Paul Calabresi K12 Award (A.M.L.), and the Minnesota Partnership for Biotechnology and Medical Genomics (A.M.L.). Imaging studies were performed using the IVIS Spectrum and Inveon micro PET/CT imaging systems at the University of Minnesota University Imaging Centers. We thank Dr. Thomas Pengo and the University of Minnesota Informatics Institute for help with the μCT data analysis. We thank Colleen Forster for help with the IHC.

Publisher Copyright:
© 2019 American Chemical Society.


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