Human CAR T cells with cell-intrinsic PD-1 checkpoint blockade resist tumor-mediated inhibition
Leonid Cherkassky, Aurore Morello, Jonathan Villena-Vargas, Yang Feng, Dimiter S. Dimitrov, David R. Jones, Michel Sadelain, Prasad S. Adusumilli
Leonid Cherkassky, Aurore Morello, Jonathan Villena-Vargas, Yang Feng, Dimiter S. Dimitrov, David R. Jones, Michel Sadelain, Prasad S. Adusumilli
View: Text | PDF
Research Article Oncology

Human CAR T cells with cell-intrinsic PD-1 checkpoint blockade resist tumor-mediated inhibition

Abstract

Following immune attack, solid tumors upregulate coinhibitory ligands that bind to inhibitory receptors on T cells. This adaptive resistance compromises the efficacy of chimeric antigen receptor (CAR) T cell therapies, which redirect T cells to solid tumors. Here, we investigated whether programmed death-1–mediated (PD-1–mediated) T cell exhaustion affects mesothelin-targeted CAR T cells and explored cell-intrinsic strategies to overcome inhibition of CAR T cells. Using an orthotopic mouse model of pleural mesothelioma, we determined that relatively high doses of both CD28- and 4-1BB–based second-generation CAR T cells achieved tumor eradication. CAR-mediated CD28 and 4-1BB costimulation resulted in similar levels of T cell persistence in animals treated with low T cell doses; however, PD-1 upregulation within the tumor microenvironment inhibited T cell function. At lower doses, 4-1BB CAR T cells retained their cytotoxic and cytokine secretion functions longer than CD28 CAR T cells. The prolonged function of 4-1BB CAR T cells correlated with improved survival. PD-1/PD-1 ligand [PD-L1] pathway interference, through PD-1 antibody checkpoint blockade, cell-intrinsic PD-1 shRNA blockade, or a PD-1 dominant negative receptor, restored the effector function of CD28 CAR T cells. These findings provide mechanistic insights into human CAR T cell exhaustion in solid tumors and suggest that PD-1/PD-L1 blockade may be an effective strategy for improving the potency of CAR T cell therapies.

Authors

Leonid Cherkassky, Aurore Morello, Jonathan Villena-Vargas, Yang Feng, Dimiter S. Dimitrov, David R. Jones, Michel Sadelain, Prasad S. Adusumilli

×

Figure 6

PD1 receptor and its ligands are upregulated in vivo.

Options: View larger image (or click on image) Download as PowerPoint
PD1 receptor and its ligands are upregulated in vivo. (A) Tumor-infiltr...
(A) Tumor-infiltrating M28z and MBBz CAR T cells overexpressed inhibitory receptors 6 days after their administration. (B) MBBz CAR T cells express lower levels of PD-1 compared with M28z CAR T cells as shown by MFI of PD1 receptor expression of tumor-infiltrating CAR T cells (TIL) 6 days after intrapleural administration. Unstransduced tumor-infiltrating T cells (UT) express a low baseline level of PD1. (C) Relative expression of PD1 mRNA in CD4 and CD8 subsets of tumor-infiltrating CAR T cells 6 days after intrapleural administration. Data are represented as fold change relative to the PD1 mRNA expression of unstimulated M28z CAR+ T cells. (D) Tumor-infiltrating M28z CAR T cells isolated from progressing tumors express inhibitory receptors PD1, TIM-3, and LAG-3. (E) Single-cell tumor suspensions harvested from mice treated with M28z CAR T cells express high levels of PD-1–binding ligands. (F) In vitro–cultured mesothelioma tumor cells express the ligands (PD-L1, PD-L2) for the PD1 receptor, and expression is further upregulated following incubation for 24 hours with IFN-γ and TNF-α. Data are representative of at least 2 to 3 independent experiments.