PD l

[Lin wilki]

Does everyone have a PDL number?  I realize it’s a test from biopsy tissue but do they normally check for it?

[Tom Galli]

Lin,

These days almost every lung cancer patient has a lab test to determine treatment eligibility for both targeted therapy and immunotherapy. For the former, an alphabet soup's worth of letters is used to categorize the biomarkers such as: ALK, EGFR, ROS1, BRAF and NTKR. These are only present in small percentages of folks who have the lung cancer subtype of adenocarcinoma.

The lab test for immunotherapy checks for two proteins: PD-1 on T cells, and PD-L1 on healthy cells and or cancer cells. Here is a quote from the LUNGevity Lung Cancer 101 site that explains the interaction of PD-1 and PD-L1: "When the PD-1 on T cells attaches to the PD-L1 on other cells, the T cells know not to attack those other cells. Cancer cells can thus evade detection by T cells, with the result that the T cells's immune response is lessened at a time when it should be active. This allows cancer cells to thrive." Immunotherapy as a treatment can work on both adenocarcinoma and squamous cell.  There is a study ongoing to check its effectiveness with small cell lung cancer.

Your next question might be what is a good PD-1 or PD-L1 number? The number is expressed as a percentage and the percentage varies from 1% or less to 99% and the level of expression suggest which of the immunotherapy drugs that may be effective.  

Stay the course.

Tom

[Lin wilki]

Thanks. I am in a clinical trial with 2 types of immunotherapy.  I know I did not have EFGR or ALK mutations which made me eligible for the trial.  Im asking my doc about my PDL