Nanobody-based CAR T cells that target the tumor microenvironment inhibit the growth of solid tumors in immunocompetent mice

Proc Natl Acad Sci U S A. 2019 Apr 16;116(16):7624-7631. doi: 10.1073/pnas.1817147116. Epub 2019 Apr 1.


Chimeric antigen receptor (CAR) T cell therapy has been successful in clinical trials against hematological cancers, but has experienced challenges in the treatment of solid tumors. One of the main difficulties lies in a paucity of tumor-specific targets that can serve as CAR recognition domains. We therefore focused on developing VHH-based, single-domain antibody (nanobody) CAR T cells that target aspects of the tumor microenvironment conserved across multiple cancer types. Many solid tumors evade immune recognition through expression of checkpoint molecules, such as PD-L1, that down-regulate the immune response. We therefore targeted CAR T cells to the tumor microenvironment via the checkpoint inhibitor PD-L1 and observed a reduction in tumor growth, resulting in improved survival. CAR T cells that target the tumor stroma and vasculature through the EIIIB+ fibronectin splice variant, which is expressed by multiple tumor types and on neovasculature, are likewise effective in delaying tumor growth. VHH-based CAR T cells can thus function as antitumor agents for multiple targets in syngeneic, immunocompetent animal models. Our results demonstrate the flexibility of VHH-based CAR T cells and the potential of CAR T cells to target the tumor microenvironment and treat solid tumors.

Keywords: chimeric antigen receptor; immunotherapy; tumor microenvironment.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Antineoplastic Agents / pharmacology
  • Immunotherapy, Adoptive / methods*
  • Mice
  • Neoplasms, Experimental
  • Receptors, Chimeric Antigen / metabolism*
  • Single-Domain Antibodies / pharmacology*
  • Tumor Microenvironment / drug effects*
  • Xenograft Model Antitumor Assays


  • Antineoplastic Agents
  • Receptors, Chimeric Antigen
  • Single-Domain Antibodies