PD-L1 by IHC, 22C3, Keytruda®

PD-L1 by IHC, 22C3, Keytruda®

Programmed death 1 (PD-1) is an immune inhibitory receptor expressed on the surface of activated T-cells and mediates suppression of the immune system.1 PD-1 interacts with the immunosuppressive PD-L1 ligand which is expressed on tumor cells, inflammatory cells, and histiocytes, and inhibits T-cell activation.2

A new class of immunotherapies, PD-1 and PD-L1 inhibitors, blocks the interaction between PD-1 and PD-L1 on the tumor cells and can enhance T-cell responses and mediate anti-tumor activity.1,2


Immunohistochemistry (IHC)

Turnaround Time

2-3 days




Non-Small-Cell Lung Cancer (NSCLC)

Lung Cancer

Gastroesophageal cancer


Formalin-fixed, paraffin-embedded (FFPE) tissue block or slides


At least three unstained slides sectioned at 4 to 5 microns. Five slides are ideal.


Paraffin block or unstained slides. Send slides within 6 months of sectioning.

Special Instructions

Global only

Causes for Rejection

Insufficient tissue; inappropriate tissue source; incorrect specimen type 

Storage Instructions

Maintain specimen at room temperature

Test Includes

Includes technical and professional components

Use Statement

Non-Small Cell Lung Cancer (NSCLC)
PD-L1 protein expression in NSCLC is determined by using Tumor Proportion Score (TPS), which is the percentage of viable tumor cells showing partial or complete membrane staining at any intensity. The specimen should be considered to have PD-L1 expression if TPS ≥ 1% and high PDL1 expression if TPS ≥ 50%.

PD-L1 IHC 22C3 pharmDx is indicated as an aid in identifying NSCLC patients for treatment with KEYTRUDA® (pembrolizumab). 

Gastric or Gastroesophageal Junction (GEJ) Adenocarcinoma
PD-L1 protein expression in gastric or GEJ adenocarcinoma is determined by using Combined Positive Score (CPS), which is the number of PD-L1 staining cells (tumor cells, lymphocytes, macrophages) divided by the total number of viable tumor cells, multiplied by 100. The specimen should be considered to have PD-L1 expression if CPS ≥ 1.

PD-L1 IHC 22C3 pharmDx is indicated as an aid in identifying gastric or GEJ adenocarcinoma patients for treatment with KEYTRUDA® (pembrolizumab).


Pembrolizumab; Programmed Death Ligand 1


  1. Kim, JW and Eder, JP, Prospects for Targeting PD-1 and PD-L1 in Various Tumor Types. Available on the website of the Cancer Network. (http://www.cancernetwork.com/oncology-journal/prospects-targeting-pd-1-and-pd-l1-various-tumor-types). Accessed July 8, 2015.
  2. Garon, EB et al., Pembrolizumab for the Treatment of Non-Small-Cell Lung Cancer. N Engl J Med 2015; 372:2018-28.

CPT Codes

The CPT codes included in this publication are in accordance with Current Procedural Terminology, a publication of the American Medical Association. CPT codes are provided here for the convenience of our clients; however, correct coding often varies from one carrier to another, and LabCorp may bill specific carriers using codes other than those shown. Clients who bill for services should verify the code(s) with the applicable payor to confirm that their use is appropriate in each case.

Profile Policy

LabCorp's policy is to provide physicians, in each instance, with the flexibility to choose appropriate tests to assure that the convenience of ordering test combinations/profiles does not prevent physicians who wish to order a test combination/profile from making deliberate informed decisions regarding which tests are medically necessary. All the tests offered in test combinations/profiles may be ordered individually using the LabCorp test request form.

Please remember that (1) when ordering tests for which Medicare or Medicaid reimbursement is sought, the physician should only order those tests that the physician believes are medically necessary for each patient, (2) that using a customized profile may result in ordering tests for which Medicare or Medicaid will deny payment, (3) that the physician should only order individual tests or a less inclusive profile where not all the tests in the customized test combination/profile are medically necessary for an individual patient, and (4) that the United States Department of Health and Human Services, Office of Inspector General, takes the position that a physician who orders medically unnecessary tests may be subject to civil penalties.

LabCorp encourages clients to contact their local LabCorp representative or LabCorp location if the testing configurations shown here do not meet individual needs for any reason, or if some other combination of procedures is desired.

Investigational Procedures

Some of the individual tests and profile test components listed in this Directory may be considered by Medicare or other insurance carriers as investigational procedures, and therefore, the test may not be payable by the carrier as a covered benefit for the patient. Medicare patients must be informed of this possibility when the physician orders tests that may fall into this category. Affected patients must be asked to sign an Advance Beneficiary Notice, agreeing to be financially responsible if the service is denied by the carrier. Additionally, for other insurance plans, physicians should inform the patient that the service(s) may not be covered by their private insurance plan and, if so, they will be financially responsible for payment. If the patient declines to accept financial responsibility, please do not order the test(s).

As with all clinical assays, results of these tests should be used only in conjunction with other medically established diagnostic elements (eg, symptoms, history, clinical impressions, results from other tests, etc). Physicians should use all the information available to them to diagnose and determine appropriate treatment for their patients. In order to obtain a current list of the procedures that may be considered investigational by Medicare or other insurance carriers, please contact your local LabCorp representative.