PD-L2 glycosylation promotes immune evasion and predicts anti-EGFR efficacy

J Immunother Cancer. 2021 Oct;9(10):e002699. doi: 10.1136/jitc-2021-002699.

Abstract

Background: Combination therapy has been explored for advanced head and neck squamous cell carcinoma (HNSCC) owing to the limited efficacy of anti-epidermal growth factor receptor (EGFR) therapy. Increased expression and glycosylation of immune checkpoint molecules in tumors are responsible for cetuximab therapy refractoriness. The role of programmed death ligand 2 (PD-L2), a ligand of PD-1, in the immune function is unclear. Here, we examined the regulatory mechanism of PD-L2 glycosylation and its role in antitumor immunity and cetuximab therapy.

Methods: Single-cell RNA sequencing and immunohistochemical staining were used to investigate PD-L2 expression in cetuximab-resistant/sensitive HNSCC tissues. The mechanism of PD-L2 glycosylation regulation was explored in vitro. The effects of PD-L2 glycosylation on immune evasion and cetuximab efficacy were verified in vitro and using mice bearing orthotopic SCC7 tumors.

Results: The PD-L2 levels were elevated and N-glycosylated in patients with cetuximab-resistant HNSCC. Glycosylated PD-L2 formed a complex with EGFR, which resulted in the activation of EGFR/signal transducer and activator of transcription 3 (STAT3) signaling and decreased the cetuximab binding affinity to EGFR. The N-glycosyltransferase fucosyltransferase (FUT8), a transcriptional target of STAT3, was required for PD-L2 glycosylation. Moreover, glycosylation modification stabilized PD-L2 by blocking ubiquitin-dependent lysosomal degradation, which consequently promoted its binding to PD-1 and immune evasion. Inhibition of PD-L2 glycosylation using Stattic, a specific STAT3 inhibitor, or PD-L2 mutation blocking its binding to FUT8, increased cytotoxic T lymphocyte activity and augmented response to cetuximab.

Conclusions: Increased expression and glycosylation of PD-L2 in tumors are an important mechanism for cetuximab therapy refractoriness. Thus, the combination of PD-L2 glycosylation inhibition and cetuximab is a potential therapeutic strategy for cancer.

Keywords: biomarkers; head and neck neoplasms; immune evation; tumor.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Immunological / pharmacology
  • B7-H1 Antigen / immunology
  • B7-H1 Antigen / metabolism*
  • Cetuximab / pharmacology
  • ErbB Receptors / antagonists & inhibitors*
  • ErbB Receptors / immunology
  • Female
  • Glycosylation
  • Head and Neck Neoplasms / drug therapy
  • Head and Neck Neoplasms / immunology
  • Head and Neck Neoplasms / metabolism
  • Humans
  • Mice
  • Mice, Inbred BALB C
  • Mice, Inbred C3H
  • Mice, Nude
  • Programmed Cell Death 1 Ligand 2 Protein / immunology
  • Programmed Cell Death 1 Ligand 2 Protein / metabolism*
  • Sequence Analysis, RNA
  • Single-Cell Analysis
  • Squamous Cell Carcinoma of Head and Neck / drug therapy
  • Squamous Cell Carcinoma of Head and Neck / immunology
  • Squamous Cell Carcinoma of Head and Neck / metabolism
  • Tumor Escape / immunology

Substances

  • Antineoplastic Agents, Immunological
  • B7-H1 Antigen
  • CD274 protein, human
  • Pdcd1lg2 protein, mouse
  • Programmed Cell Death 1 Ligand 2 Protein
  • EGFR protein, human
  • EGFR protein, mouse
  • ErbB Receptors
  • Cetuximab