B2M gene expression shapes the immune landscape of lung adenocarcinoma and determines the response to immunotherapy

Abstract

Loss of the B2M gene is associated with tumour immune escape and resistance to immunotherapy. However, genetic alterations of the B2M gene are rare. We performed an integrative analysis of the mutational and transcriptional profiles of large cohorts of non‐small‐cell lung cancer (NSCLC) patients and found that epigenetic downregulation of B2M is common. B2M‐low tumours exhibit a suppressive immune microenvironment characterized by reduced infiltration of immune cells of various lineages; in B2M‐high tumours, more T and natural killer cells are present, but their activities are constrained by immune checkpoint molecules, indicating the diverse mechanisms of immune evasion. High levels of B2M mRNA, but not PD‐L1, are correlated with an enhanced response to PD‐1‐based immunotherapy, suggesting its value for immunotherapy response prediction in solid tumours. Notably, a high tumour mutation burden (TMB) is associated with low B2M expression, which may explain the poor predictive value of the TMB in some situations. In syngeneic mouse models, genetic ablation of B2M in tumour cells causes resistance to PD‐1‐based immunotherapy, and B2M knockdown also diminishes the therapeutic efficacy. Moreover, forced expression of B2M in tumour models improves the response to immunotherapy, suggesting that B2M levels have significant impacts on treatment outcomes. Finally, we provide insight into the roles of transcription factors and KRAS mutations in B2M expression and the anticancer immune response. In conclusion, genetic and epigenetic regulation of B2M fundamentally shapes the NSCLC immune microenvironment and may determine the response to checkpoint blockade‐based immunotherapy.

Driver Gene Alterations in Malignant Progression of Gastric Cancer

“…PIK3CA indicated an increasing risk of death in gastric cancer patients ( 22 ). B2M shapes the immune landscape of lung adenocarcinoma and causes resistance to PD-1-based immunotherapy ( 23 ). Loss of PTEN promotes resistance to T cell-mediated immunotherapy ( 24 ).…”

Mechanisms of MHC-I Downregulation and Role in Immunotherapy Response

“…TsMHC-I associates with improved response to ICI and increased amounts of tumor infiltrating lymphocytes ( 44 , 81 , 83 , 87 , 90 )Loss of MHC-I antigen presentation is common in cancers and allows tumors to evade immune surveillance. Although MHC-I loss due to structural genetic alterations such as β2M loss are irreversible, post-transcriptional downregulation of MHC-I can be reversed ( Figure 2 ).…”

The Stroma and Tumor Microenvironment Are Not the Most Instrumental Players in Tumor Cells Immune Evasion, Growth, and Resistance to Therapy

“…113 Of importance too, is to examine in depth the metabolic changes that render the cell, and especially the cell surface membrane deaf to contact inhibition signals, and unable to properly display MHC class I molecules, Fas ligand and other activators and targets of cytotoxic immune cells. 4,102 Very recently, abundant cholesterol sulfate-producing cancer cells were found to exhibit remarkable resistance to cancer-specific T-cell transfer and immunotherapeutic interventions. 114 Numerous articles have documented the role of excessive content of surface membrane sphingomyelin and down-regulation of the membrane-associated neutral sphingomyelinase in tumor immune evasion, initiation, growth and drug resistance of hepatic, breast, ovarian, brain, and bone cancer growth and metastasis.…”