PD-L1 (22C3) Dako CPS IHC Test

The PD-L1 (22C3) Dako CPS IHC Test is an Immunohistochemistry (IHC) test designed to assess the level of PD-L1 expression on tumor cells. This test is critical for cancer diagnosis, particularly in non-small cell lung cancer (NSCLC), to determine whether a patient is suitable for immune checkpoint inhibitor therapies such as Keytruda. The PD-L1 IHC test provides essential information for personalized cancer treatment, helping oncologists in Dubai make informed decisions.

2. Purpose / Clinical Significance:

The PD-L1 (22C3) Dako CPS IHC Test is used for:

• Assessing PD-L1 Expression: It detects PD-L1 protein expression on tumor cells, which is an important biomarker in cancer immunotherapy. PD-L1 plays a crucial role in how tumors evade the immune system, making it a key target for treatment.

• Guiding Immunotherapy Decisions: The PD-L1 IHC test is primarily used to guide the use of immune checkpoint inhibitors like Pembrolizumab (Keytruda), which block PD-L1 and help the immune system fight cancer.

• Personalized Treatment Plans: By determining whether PD-L1 is present, this test helps doctors tailor treatments to individual patients, improving treatment outcomes, especially for patients with lung cancer.

• Non-Small Cell Lung Cancer (NSCLC): The PD-L1 test is commonly used in NSCLC patients to determine whether immunotherapy is a viable option, enhancing the quality of treatment in Dubai.

3. Principle:

The PD-L1 (22C3) Dako CPS IHC Test works by utilizing Immunohistochemistry (IHC), a method that uses specific antibodies to detect proteins in tissue samples:

• Antibody Binding: The test uses the PD-L1 22C3 antibody, which binds to the PD-L1 protein on the surface of cancer cells.

• Colorimetric Detection: Once the antibody binds to PD-L1, a color reaction occurs, allowing the expression level of PD-L1 to be visualized under a microscope.

• CPS Scoring: The CPS (Combined Positive Score) method is used to quantify the PD-L1 expression. It is calculated by dividing the number of PD-L1 positive cells (tumor cells, lymphocytes, and macrophages) by the total number of viable tumor cells and multiplying by 100.

• Objective Results: The results are scored based on the intensity of staining, allowing for a clear and objective assessment of PD-L1 expression.

4. Specimen Requirements:

The PD-L1 (22C3) Dako CPS IHC Test requires a tumor tissue sample. The specimen can be obtained from:

• Tumor Biopsy: A tissue biopsy of the tumor is commonly taken from patients suspected of having cancer, especially lung cancer.

• Surgical Resection: If a tumor has been surgically removed, tissue samples can be used for the PD-L1 test.

• Needle Biopsy: For patients unable to undergo surgery, a needle biopsy may be performed to extract a tumor sample for testing.

• Formalin-Fixed, Paraffin-Embedded (FFPE): The tissue sample must be preserved using formalin fixation and paraffin embedding, which is standard practice in pathology.

5. Common Methods:

The test is performed using the following steps:

• Sample Preparation: The tumor tissue is prepared and stained with the PD-L1 22C3 antibody.

• Immunohistochemical Staining: The tissue is exposed to the antibody, and a colorimetric reaction occurs where PD-L1 expression is detected.

• Microscopic Analysis: After staining, the tissue is examined under a microscope, where the presence of PD-L1 expression is recorded and scored based on intensity.

• CPS Scoring Method: The Combined Positive Score (CPS) quantifies the level of PD-L1 expression, considering all tumor cells, lymphocytes, and macrophages.

6. Who Should Take the PD-L1 (22C3) Dako CPS IHC Test?

The PD-L1 (22C3) Dako CPS IHC Test is especially useful for:

• Non-Small Cell Lung Cancer (NSCLC) Patients: Those diagnosed with NSCLC, particularly if they are candidates for immune checkpoint inhibitors like Pembrolizumab (Keytruda).

• Patients with Metastatic Cancer: Those whose cancer has spread to other organs may benefit from testing to determine if they are eligible for PD-L1-based therapies.

• Patients Seeking Personalized Treatment: The test is crucial for patients who need a personalized treatment plan, especially for those looking to explore immunotherapy options.

• Cancer Patients with Poor Prognosis: If a cancer is aggressive and traditional treatments have failed, testing for PD-L1 expression helps assess the likelihood of responding to immunotherapy.

7. Interpretation of Results:

• CPS Score of 1 or Higher: A CPS score of 1 or above indicates that there is detectable PD-L1 expression, and the patient may benefit from immunotherapy such as Pembrolizumab (Keytruda).

• CPS Score of Less Than 1: A score below 1 suggests minimal or no PD-L1 expression, and immunotherapy may not be effective for that patient.

• Positive Result: A positive result with a high CPS score indicates that the cancer is likely to respond well to PD-L1 inhibitors.

• Negative Result: A negative result suggests that immunotherapy may not be an appropriate option, and alternative treatments should be considered.

8. Reference Range:

• PD-L1 Expression Levels: The CPS score is the reference range used to interpret results, where a CPS score of 1 or higher indicates positive PD-L1 expression.

• CPS of 50 or Higher: A CPS of 50 or higher is often used as a cutoff for strong response to immune checkpoint inhibitors, such as Pembrolizumab.

• CPS of Less Than 1: A score of less than 1 typically indicates a low likelihood of response to immunotherapy.

9. Follow-up Testing:

• Further Genetic Profiling: If PD-L1 expression is detected, additional genetic profiling may be recommended to assess other potential mutations in the cancer.

• Immunotherapy Treatment: For those with a positive PD-L1 test, immunotherapy such as Pembrolizumab may be initiated.

• Regular Monitoring: Patients undergoing immunotherapy will be monitored for treatment efficacy and side effects, with periodic follow-up testing to assess their progress.

10. Conclusion:

The PD-L1 (22C3) Dako CPS IHC Test is a key diagnostic tool for evaluating PD-L1 expression in cancer patients, particularly those with non-small cell lung cancer (NSCLC). By guiding decisions around immunotherapy treatment, this test allows for personalized cancer treatment, improving outcomes for patients in Dubai. Early detection of PD-L1 expression helps doctors determine the most effective treatments and offer targeted care, enhancing the quality of life and overall prognosis.