PD – L1 TESTING

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  • Programmed Death-1 (PD-1) and PD-1 Ligand (PD-L1) are immune checkpoint proteins that are crucial for self-tolerance.
  • Induction of the PD1/PD-L1 pathway represents an adaptive immune resistance mechanism exerted by tumor cells in response to endogenous antitumor activity.
  • FDA approved  Immuno-oncology agent, the PD-1 inhibitors Pembrolizumab , for the treatment of previously treated advanced Non-Small cell Lung Cancer (NSCLC), Both work by blocking PD-1 on the surface of immune cells, disrupting its interaction with PD-L1 on cancer cells. This lifts a natural brake on the immune system (i.e., PD-1), allowing it to kill cancer cells.
  • PDL-1 expression is important to identify patients most likely to benefit from therapy.
  • Patients with metastatic NSCLC whose tumors have high PD-L1 expression [(Tumor Proportion Score (TPS) =50%)] with no EGFR or ALK genomic tumor aberrations, and no prior systemic chemotherapy treatment for metastatic NSCLC.
  • Patients with metastatic NSCLC whose tumors express PD-L1 (TPS =1%) with disease progression on or after platinum-containing chemotherapy.

PD-L1-TESTING

Clinical utility

  • To assess PD-L1 expression in Non-squamous NSCLC tissue specimens.
  • Aids in identifying patients who will benefit from Pembrolizumab.

When to test:

  • Test patients for PDL-1 expression at time of diagnosis, concurrent with differentiation of histologic subtypes.
  • In patients who were not tested at diagnosis, testing prior to second line or greater treatment can also inform treatment decisions.