Long-term persistence and functionality of adoptively transferred antigen-specific T cells with genetically ablated PD-1 expression

Proc Natl Acad Sci U S A. 2023 Mar 7;120(10):e2200626120. doi: 10.1073/pnas.2200626120. Epub 2023 Feb 28.

Abstract

Engagement of the inhibitory T cell receptor programmed cell death protein 1 (PD-1) associates with dysfunctional states of pathogen- or tumor-specific T cells. Accordingly, systemic antibody-mediated blockade of PD-1 has become a central target for immunotherapies but is also associated with severe toxicities due to loss of peripheral tolerance. Therefore, selective ablation of PD-1 expression on adoptively transferred T cells through direct genetic knockout (KO) is currently being explored as an alternative therapeutic approach. However, since PD-1 might also be required for the regulation of physiological T cell function and differentiation, the suitability of PD-1 as an engineering target is controversial. In this study, we systematically investigated the maintenance of T cell functionality after CRISPR/Cas9-mediated PD-1 KO in vivo during and after acute and chronic antigen encounter. Under all tested conditions, PD-1 ablation preserved the persistence, differentiation, and memory formation of adoptively transferred receptor transgenic T cells. Functional PD-1 KO T cells expressing chimeric antigen receptors (CARs) targeting CD19 could be robustly detected for over 390 d in a syngeneic immunocompetent mouse model, in which constant antigen exposure was provided by continuous B cell renewal, representing the longest in vivo follow-up of CAR-T cells described to date. PD-1 KO CAR-T cells showed no evidence for malignant transformation during the entire observation period. Our data demonstrate that genetic ablation of PD-1 does not impair functionality and longevity of adoptively transferred T cells per se and therefore may be pursued more generally in engineered T cell-based immunotherapy to overcome a central immunosuppressive axis.

Keywords: CRISPR/Cas9; PD-1; adoptive T cell therapy; genetic engineering.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Animals
  • Animals, Genetically Modified
  • Antibodies, Blocking
  • Mice
  • Programmed Cell Death 1 Receptor* / genetics
  • T-Lymphocytes*

Substances

  • Programmed Cell Death 1 Receptor
  • Adaptor Proteins, Signal Transducing
  • Antibodies, Blocking