Immune Escape

Tumor cells can escape the antitumor immune response in several ways

Tumor cells can evade the immune system by disrupting any of the key T-cell activities necessary to initiate and perpetuate an antitumor immune response: T-cell generation, T-cell infiltration, or tumor cell killing.1-3

Disruption of any steps of the cancer immunity cycle can ultimately result in tumor growth.1

PD-L1 cancer immunity cycle

*Tumor cell killing by CD8+ T cells.

PD-L1 may need to be targeted simultaneously with other pathways to restore the cancer immunity cycle

As a key immunosuppressive driver, the PD-L1 pathway is an important target that can help invigorate antitumor T-cell activity in the tumor microenvironment.3,4

  • PD-L1 inhibition can help restore tumor cell killing4*
PD-L1 tumor killing PD-L1 tumor killing


  1. In cancer, the PD-L1 ligand is expressed on tumor cells and immune cells. When bound to its receptors, PD-1 and B7.1 on T cells, PD-L1 deactivates cytotoxic T cells
  2. PD-L1 inhibition prevents T-cell deactivation
  3. Reinvigorated T cells can then attack and kill tumor cells

*Tumor cell killing by CD8+ T cells.

However, cancers may use multiple immune escape mechanisms. Targeting PD-L1 simultaneously with other pathways may be necessary to restore a fully functional cancer immunity cycle.3

Genentech is actively researching pathway combinations with PD-L1.5-7

PD-L1 restoring cancer immunotherapy

PD-L1=programmed death-ligand 1; VEGF=vascular endothelial growth factor.


  1. Chen DS, Mellman I. Immunity. 2013;39:1-10. PMID: 23890059
  2. Chen DS, Mellman I. Nature. 2017;541:321-330. PMID: 28102259
  3. Kim JM, Chen DS. Ann Oncol. 2016;27:1492-1504. PMID: 27207108
  4. Chen DS, Irving BA, Hodi FS. Clin Cancer Res. 2012;18:6580-6587. PMID: 23087408
  5. US National Institutes of Health. Accessed January 31, 2019.
  6. US National Institutes of Health. Accessed January 31, 2019.
  7. US National Institutes of Health. Accessed January 31, 2019.
  8. Gebremeskel S, Johnston B. Oncotarget. 2015;6:41600-41619. PMID: 26486085