Abrogation of IFN-γ Signaling May not Worsen Sensitivity to PD-1/PD-L1 Blockade

Abstract

Programmed cell death protein 1 (PD-1)/PD-1 ligand 1 (PD-L1) blockade is a promising therapy for various cancer types, but most patients are still resistant. Therefore, a larger number of predictive biomarkers is necessary. In this study, we assessed whether a loss-of-function mutation of the interferon (IFN)-γ receptor 1 (IFNGR1) in tumor cells can interfere with anti-PD-L1 therapy. For this purpose, we used the mouse oncogenic TC-1 cell line expressing PD-L1 and major histocompatibility complex class I (MHC-I) molecules and its TC-1/A9 clone with reversibly downregulated PD-L1 and MHC-I expression. Using the CRISPR/Cas9 system, we generated cells with deactivated IFNGR1 (TC-1/dIfngr1 and TC-1/A9/dIfngr1). In tumors, IFNGR1 deactivation did not lead to PD-L1 or MHC-I reduction on tumor cells. From potential inducers, mainly IFN-α and IFN-β enhanced PD-L1 and MHC-I expression on TC-1/dIfngr1 and TC-1/A9/dIfngr1 cells in vitro. Neutralization of the IFN-α/IFN-β receptor confirmed the effect of these cytokines in vivo. Combined immunotherapy with PD-L1 blockade and DNA vaccination showed that IFNGR1 deactivation did not reduce tumor sensitivity to anti-PD-L1. Thus, the impairment of IFN-γ signaling may not be sufficient for PD-L1 and MHC-I reduction on tumor cells and resistance to PD-L1 blockade, and thus should not be used as a single predictive marker for anti-PD-1/PD-L1 cancer therapy.

CD80 Expression on Tumor Cells Alters Tumor Microenvironment and Efficacy of Cancer Immunotherapy by CTLA-4 Blockade

“…However, the interaction of mouse CTLA-4 with CD80 has been reported to outcompete the tumor-suppressive CD80 and PD-L1 in cis interaction [ 51 ]. This corresponds to our previous observation showing that deactivation of PD-L1 in the TC-1 cell line markedly reduced the tumorigenicity of these cells, which implies the pro-tumorigenic role of the PD-L1 molecule, rather than CD80/PD-L1-mediated tumor suppression [ 52 ]. We, therefore, assume that PD-L1 on tumor cells did not effectively control the CTLA-4/CD80 axis in TC-1- and TC-1/dCD80-1-induced tumors.…”

“…Single-cell suspensions were prepared from tumors as previously described [ 52 ] and stimulated prior to staining with panels of antibodies for flow cytometry analysis of the T cells. In total, 2.5 × 10 6 cells were cultivated for 3 hours in 2 mL of Roswell Park Memorial Institute (RPMI) 1640 medium (Sigma-Aldrich, Merck KGaA) supplemented with 10% FCS (Biosera), 100 IU/mL penicillin, 100 μg/mL streptomycin (Biosera), and 50 µM 2-mercaptoethanol and containing 81 nM phorbol 12-myristate 13-acetate, 1.34 µM ionomycin, 2 µM monensin, and 10.6 µM brefeldin A (Abcam, Cambridge, UK).…”

Immunomodulatory potential of natural products from herbal medicines as immune checkpoints inhibitors: Helping to fight against cancer via multiple targets

“…Notably, IFN‐γ stimulation increases the basal level or exosomal level of PD‐L1 to induce immunosuppression and facilitate tumor growth. However, the impairment of IFN‐γ signaling is not responsible for MHC‐I reduction and the anticancer sensitivity to PD‐L1 blockade 56,69,70 . It comes as no surprise that other key regulators also play important roles in ICB.…”

“…However, the impairment of IFN‐γ signaling is not responsible for MHC‐I reduction and the anticancer sensitivity to PD‐L1 blockade. 56 , 69 , 70 It comes as no surprise that other key regulators also play important roles in ICB.…”