Li et al. showed aberrant high expression of the B7-H3 Ig4 isoform by multiple solid human tumor types, and isolated nanobodies specific for major B7-H3 domains from camel VHH phage libraries. Human CAR T cells based on nanobodies specific for novel B7-H3 IgC epitopes showed the strongest antigen binding and lysis of B7-H3+ human neuroblastoma and PDAC cells in vitro. In mice, CAR T cells infiltrated and mediated strong antitumor activity against large and metastatic neuroblastoma and PDAC xenografts. CAR T cells collected from spleens showed antigen-specific upregulation of transcripts related to translation, protein synthesis, and T cell metabolism ex vivo.
Contributed by Paula Hochman
ABSTRACT: Rational design of chimeric antigen receptor T (CAR-T) cells based on the recognition of antigenic epitopes capable of evoking the most potent CAR activation is an important objective in optimizing immune therapy. In solid tumors, the B7-H3 transmembrane protein is an emerging target that harbours two distinct epitope motifs, IgC and IgV, in its ectodomain. Here, we generate dromedary camel nanobodies targeting B7-H3 and demonstrate that CAR-T cells, based on the nanobodies recognizing the IgC but not IgV domain, had potent antitumour activity against large tumors in female mice. These CAR-T cells are characterized by highly activated T cell signaling and significant tumor infiltration. Single-cell transcriptome RNA sequencing coupled with functional T-cell proteomics analysis uncovers the top-upregulated genes that might be critical for the persistence of polyfunctional CAR-T cells in mice. Our results highlight the importance of the specific target antigen epitope in governing optimal CAR-T activity and provide a nanobody-based B7-H3 CAR-T product for use in solid tumor therapy.
Author Info: (1) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (2) Laboratory of Molecular Biology, Center for Cancer Researc
Author Info: (1) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (2) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (3) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (4) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (5) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (6) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (7) IsoPlexis Corporation, Branford, CT, 06405, USA. (8) IsoPlexis Corporation, Branford, CT, 06405, USA. (9) IsoPlexis Corporation, Branford, CT, 06405, USA. (10) Molecular Histopathology Laboratory, Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA. (11) Genetics Branch, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. (12) Mouse Cancer Genetics Program, Center for Cancer Research, National Cancer Institute, Frederick, MD, 21702, USA. (13) Laboratory of Molecular Biology, Center for Cancer Research, National Cancer Institute, Bethesda, MD, 20892, USA. homi@mail.nih.gov.
