Lymphocyte Activation Gene-3 Modulation in Tumor Immunology

Lymphocyte activation gene-3 (LAG-3) has emerged as a pivotal immune checkpoint in the regulation of T cell responses within the tumour microenvironment. Structurally related to CD4, LAG-3 binds major histocompatibility complex class II and additional ligands such as fibrinogen-like protein 1 (FGL1), transmitting inhibitory signals that curtail T cell proliferation, cytokine production and cytotoxic activity. Its expression is upregulated on chronically stimulated and exhausted T cells, where it synergises with programmed cell death protein 1 (PD-1) to reinforce immune suppression and facilitate tumour immune escape. Therapeutic modulation of LAG-3, through monoclonal antibodies, fusion proteins or bispecific constructs, aims to restore effector function, overcome resistance to existing checkpoint blockade and enhance antitumour immunity. Preclinical models have elucidated LAG-3’s role in limiting CD4+ helper and CD8+ cytotoxic subsets, while clinical investigations have demonstrated safety and preliminary efficacy of LAG-3 targeting alone or in combination with PD-1 inhibitors. Beyond lymphocytes, LAG-3 modulation influences antigen-presenting cell activation and the composition of tumour-infiltrating immune populations. Together, these insights underpin a growing portfolio of LAG-3-directed strategies, positioning this checkpoint as a versatile node for improving outcomes across diverse malignancies.

Research from Nature Portfolio

Recent studies have explored dual blockade strategies and the molecular circuits that regulate LAG-3 ligand expression. A first-in-human trial evaluated a bispecific DART molecule targeting PD-1 and LAG-3 in patients with advanced solid tumours and haematological cancers. The agent was well tolerated, defined a recommended phase 2 dose and yielded objective responses in PD-1-refractory tumours and LAG-3 + non-Hodgkin lymphomas. Combination with an anti-HER2 antibody further expanded activity in HER2-positive disease, including cases unresponsive to standard anti-PD-1 therapies. In parallel, research into the liver metastatic niche revealed that tumour-associated macrophages drive upregulation of a deubiquitinase that stabilises FGL1, thereby bolstering immune escape. Disruption of the macrophage–deubiquitinase–FGL1 axis not only inhibited metastatic progression but also sensitised lesions to checkpoint blockade, while circulating FGL1 levels emerged as a predictor of therapeutic benefit.

Lymphocyte Activation Gene-3 Modulation in Tumor Immunology publication trend

The graph below shows the total number of articles in lymphocyte activation gene-3 modulation in tumor immunology across all publications each year (not limited to Nature Index journals).

Technical terms

LAG-3: inhibitory receptor on activated lymphocytes that dampens T cell function upon binding to ligands such as MHC II and FGL1.

Immune checkpoint: regulatory pathway that restrains immune activation to maintain self-tolerance and limit tissue damage, often exploited by tumours.

FGL1: fibrinogen-like protein 1, a secreted ligand of LAG-3 that promotes immune evasion by stabilising inhibitory receptor engagement.

Bispecific antibody: engineered immunoglobulin derivative capable of binding two distinct antigens simultaneously to enhance therapeutic efficacy.

Tumour microenvironment: local cellular milieu surrounding a tumour, comprising immune cells, stromal components and soluble factors that influence tumour progression and therapy response.

References

1. The PD-1- and LAG-3-targeting bispecific molecule tebotelimab in solid tumors and hematologic cancers: a phase 1 trial. Nature Medicine (2023).
2. Targeting LAG-3, TIM-3, and TIGIT for cancer immunotherapy. Journal of Hematology & Oncology (2023).
3. The liver microenvironment orchestrates FGL1-mediated immune escape and progression of metastatic colorectal cancer. Nature Communications (2023).
4. LAG3 and PD1 co-inhibitory molecules collaborate to limit CD8 + T cell signaling and dampen antitumor immunity in a murine ovarian cancer model. Oncotarget (2015).
5. Targeting LAG-3 and PD-1 to Enhance T Cell Activation by Antigen-Presenting Cells. Frontiers in Immunology (2018).
6. LAG3’s Enigmatic Mechanism of Action. Frontiers in Immunology (2021).
7. Immune Checkpoint LAG3 and Its Ligand FGL1 in Cancer. Frontiers in Immunology (2022).