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The role of the PD-L1 pathway in maintaining homeostasis

The role of the PD-L1 pathway in maintaining homeostasis

Under normal conditions, programmed death-ligand 1 (PD-L1) plays an important role in maintaining immune homeostasis.1 PD-L1 and PD-L2 bind to specific receptors on T cells. When bound to their receptors, cytotoxic T-cell activity is downregulated, thereby protecting normal cells from collateral damage.1,2

The PD-L1 pathway in cancer

  • In many cancers, PD-L1 is over expressed on tumor cells and tumor-infiltrating immune cells, such as macrophages and dendritic cells3,4
  • PD-L1 binds to B7.1 and PD-1 on cytotoxic T cells, inhibiting the antitumor immune response3-5
  • PD-L1 is a potential biomarker4,6

PD-L1 expression detected in immunohistochemistry staining of lung cancer tumor7

Lung cancer tumor cells, Tumor-infiltrating immune cells


  1. Topalian SL, Drake CG, Pardoll DM. Targeting the PD-1/B7-H1(PD-L1) pathway to activate anti-tumor immunity. Curr Opin Immunol. 2012;24:207-212. PMID: 22236695
  2. Park JJ, Omiya R, Matsumura Y, et al. B7-H1/CD80 interaction is required for the induction and maintenance of peripheral T-cell tolerance. Blood. 2010;116:1291-1298. PMID: 20472828
  3. Chen DS, Mellman I. Oncology meets immunology: the cancer-immunity cycle. Immunity. 2013;39:1-10. PMID: 23890059
  4. Chen DS, Irving BA, Hodi FS. Molecular pathways: next-generation immunotherapy—inhibiting programmed death-ligand 1 and programmed death-1. Clin Cancer Res. 2012;18:6580-6587. PMID: 23087408
  5. Keir ME, Butte MJ, Freeman GJ, Sharpe AH. PD-1 and its ligands in tolerance and immunity. Annu Rev Immunol. 2008;26:677-704. PMID: 18173375
  6. Quezada SA, Peggs KS. Exploiting CTLA-4, PD-1 and PD-L1 to reactivate the host immune response against cancer. Br J Cancer. 2013;108:1560-1565. PMID: 23511566
  7. Data on file. Genentech, Inc.

Genentech is committed to researching potential strategies in cancer immunotherapy and is actively investigating the PD-L1 pathway.

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