PD-L1, PD1, TMB and Lung Cancer

Support for this educational program provided by Amgen, AstraZeneca, Blueprint Medicines, Bristol Myers Squibb, Genentech, Lilly Oncology, Merck, Novartis and Pfizer.

Researchers have identified certain biomarkers in lung cancer tumors. PD-L1 and TMB are markers that may help provide information about whether or not a patient would benefit from immunotherapy to treat their lung cancer. The information below pertains to patients who do not a have an error in two specific genes, EGFR or ALK, in their tumor. Little is known about markers for immunotherapy in patients with EGFR of ALK gene abnormalities. Talk with your doctor for more information.

What are PD-L1 and PD-1?

Immunotherapy activates the immune system to attack cancer cells. The most common type of lung cancer immunotherapy is called an immune checkpoint inhibitor. The most commonly used immunotherapies for lung cancer block the interaction between PD-1 and PD-L1. PD-1 is a receptor often on the surface of immune cells. PD-L1 is a protein that has a broader presence, including on the tumor cells.

How do you know your levels of PD-L1 and what do they mean?

At the time of diagnosis, all new lung cancer patients should have their PD-L1 levels tested. This involves looking at tumor tissue under a microscope using a test called immunohistochemical staining. A PD-L1 test measures what percentage of cells in a tumor “express” PD-L1. Tumors that express high amounts of PD-L1 (50% or greater) may respond particularly well to checkpoint inhibitors (a type of immunotherapy drug).

If you have not had your PD-L1 levels tested, ask your doctor if it is right for you.  

Learn more about the different types of biomarker tests here.

How does PD-L1 level impact treatment options?

Results of PD-L1 tests help inform your treatment options. If you have high levels of PD-L1 and no other biomarker with an approved targeted therapy, then your doctor will likely recommend you go on an immunotherapy drug as a first-line treatment (that means you get an immunotherapy drug before any other treatment). Your doctor may recommend that approach even if you have some expression of PD-L1, but less than 50%. Your doctor might also suggest combining immunotherapy with chemotherapy. Ask your doctor about your PD-L1 levels and what they mean for your treatment options.

What is TMB?

TMB stands for tumor mutation burden. Tumor mutation burden looks for the number of mutations that are in a tumor that can change proteins in a patient's tumor cells. For immunotherapies to be effective, the immune system has to recognize one of these abnormal proteins. That is why it is thought that having more mutations may improve your chance of responding well to immunotherapy. Talk with your doctor about this test and if it is right for you.

Work with your doctor to discuss your goals and options each time you have to make a treatment decision. The three big questions to ask are:

1. What is the goal of this treatment?
2. What are the potential side effects?
3. What other options do I have?

Research is happening at a rapid pace and your doctor should be up to date on the recommendations for your specific type of lung cancer. If you don’t feel comfortable with the answers you are receiving, do not hesitate to seek out a second opinion.