PDL1 (Immunotherapy) Tests

PDL1, also known as programmed death-ligand 1, is a protein that plays a crucial role in the immune system. It is expressed on the surface of certain cells, including cancer cells, and helps to regulate the immune response by binding to its receptor, PD-1, on T-cells.

What are PDL1 tests?

PDL1 tests are diagnostic assays used to measure the expression of PDL1 protein on tumor cells. These tests are typically performed on tissue samples from cancer patients and are used to determine whether a patient's tumor is likely to respond to immunotherapy treatments that target the PD-1/PDL1 pathway.

Types of PDL1 tests

There are several types of PDL1 tests available, including:

• Immunohistochemistry (IHC) assays: These tests use antibodies to detect PDL1 protein on tumor cells. IHC assays are the most commonly used method for PDL1 testing.
• Fluorescence in situ hybridization (FISH) assays: These tests use fluorescent probes to detect PDL1 gene expression in tumor cells.
• Real-time polymerase chain reaction (RT-PCR) assays: These tests measure the levels of PDL1 mRNA in tumor cells.

How are PDL1 tests used?

PDL1 tests are used to:

• Predict response to immunotherapy: Patients with high PDL1 expression on their tumor cells may be more likely to respond to immunotherapy treatments that target the PD-1/PDL1 pathway.
• Identify patients who may benefit from combination therapies: PDL1 tests can help identify patients who may benefit from combination therapies that include immunotherapies and other cancer treatments.
• Monitor disease progression: PDL1 tests can be used to monitor changes in PDL1 expression over time, which can help track disease progression and response to treatment.

Limitations of PDL1 tests

PDL1 tests have several limitations, including:

• Variability in test results: Different PDL1 tests may produce different results, which can make it difficult to interpret the data.
• Limited standardization: There is currently no standardized method for PDL1 testing, which can lead to variability in test results between laboratories.
• Complexity of the PD-1/PDL1 pathway: The PD-1/PDL1 pathway is complex and involves multiple factors, which can make it difficult to interpret PDL1 test results.

Clinical applications of PDL1 tests

PDL1 tests have been approved for use in several clinical settings, including:

• Non-small cell lung cancer (NSCLC): PDL1 tests are used to identify patients with NSCLC who may benefit from immunotherapy treatments.
• Melanoma: PDL1 tests are used to identify patients with melanoma who may benefit from immunotherapy treatments.
• Renal cell carcinoma: PDL1 tests are used to identify patients with renal cell carcinoma who may benefit from immunotherapy treatments.