Rath and Bajwa et al. redirected human T cells by transgenic expression of TCR8, which encodes the co-receptor CD8αβ, and an MHC-I-restricted tumor-associated antigen (TAA)-specific TCR, or only the TCR. TCR8+CD4+, TCR8+CD8+ and TCR+CD8+ (but not TCR+CD4+) T cells acted comparably upon bulk coculture with TAA+ cells. Yet, single-cell analyses showed that TCR8+CD4+ T cells best sustained upregulated expression of the most numerous and diverse sets of genes underlying proliferative, cytolytic, costimulatory, cell cycle, and metabolic pathways, representing a less differentiated and less exhausted profile, and better controlled a leukemia xenograft in vivo.

Contributed by Paula Hochman

ABSTRACT: Transgenic coexpression of a class I–restricted tumor antigen–specific T cell receptor (TCR) and CD8 (TCR8) redirects antigen specificity of CD4+ T cells. Reinforcement of biophysical properties and early TCR signaling explain how redirected CD4+ T cells recognize target cells, but the transcriptional basis for their acquired antitumor function remains elusive. We, therefore, interrogated redirected human CD4+ and CD8+ T cells by single-cell RNA sequencing and characterized them experimentally in bulk and single-cell assays and a mouse xenograft model. TCR8 expression enhanced CD8+ T cell function and preserved less differentiated CD4+ and CD8+ T cells after tumor challenge. TCR8+ CD4+ T cells were most potent by activating multiple transcriptional programs associated with enhanced antitumor function. We found sustained activation of cytotoxicity, costimulation, oxidative phosphorylation– and proliferation-related genes, and simultaneously reduced differentiation and exhaustion. Our study identifies molecular features of TCR8 expression that can guide the development of enhanced immunotherapies.

Author Info: (1) Department of Oncology UNIL-CHUV, Lausanne University Hospital, Ludwig Institute for Cancer Research, University of Lausanne, Lausanne, Switzerland. (2) Center for Cell and Gen

Author Info: (1) Department of Oncology UNIL-CHUV, Lausanne University Hospital, Ludwig Institute for Cancer Research, University of Lausanne, Lausanne, Switzerland. (2) Center for Cell and Gene Therapy, Baylor College of Medicine, Houston Methodist Hospital and Texas Children’s Hospital, Houston, TX, USA. (3) Department of Chemical and Biomolecular Engineering, University of Houston, TX, USA. (4) Biostatistics Shared Resource, Dan L. Duncan Comprehensive Cancer Center, Baylor College of Medicine, Houston, TX, USA. (5) Department of Medicine, Baylor College of Medicine, Houston, TX, USA. (6) Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA. (7) Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.