Ordering Recommendation

Use for non-small cell lung cancer (NSCLC) specimens only. Companion diagnostic testing to aid in the prediction of response to pembrolizumab (KEYTRUDA) as first- or second-line monotherapy for patients with NSCLC or to cemiplimab-rwlc (LIBTAYO) as first-line treatment of patients with advanced NSCLC whose tumors have a TPS of ≥50 percent. For esophageal squamous cell carcinoma, urothelial carcinoma, cervical carcinoma, head and neck squamous cell carcinoma (HNSCC), or triple-negative breast cancer (TNBC) specimens, see PD-L1 22C3 IHC with Combined Positive Score (CPS) Interpretation, pembrolizumab (KEYTRUDA) (3000197). Refer to the PD-L1 Testing Algorithm for more information.


22C3 IP






1-5 days

New York DOH Approval Status

This test is New York DOH approved.

Specimen Required

Patient Preparation

Tumor tissue.

Specimen Preparation

Formalin fix (10 percent neutral buffered formalin) and paraffin embed specimen. Protect paraffin block and/or slides from excessive heat. Transport tissue block or 5 unstained (3- to 5-micron thick sections), positively charged slides in a tissue transport kit (ARUP supply #47808 recommended but not required), available online through eSupply using ARUP Connector contact ARUP Client Services at (800) 522-2787. (Min: 3 slides) If sending precut slides, do not oven bake.

Storage/Transport Temperature

Room temperature. Also acceptable: Refrigerated. Ship in cooled container during summer months.

Unacceptable Conditions

Tumor types that have FDA approval for PD-L1 22C3 testing with combined positive score (CPS). Paraffin block with no tumor tissue remaining. Specimens fixed in any fixative other than 10 percent neutral buffered formalin. Decalcified specimens. Specimens with fewer than 100 viable tumor cells.


Include surgical pathology report and indicate tissue site with the test order. For additional technical details, please contact ARUP Client Services at (800) 522-2787.
If multiple specimens (blocks or slides) are sent to ARUP, they must be accompanied by one of the following: an order comment indicating that the ARUP pathologist should choose the specimen most appropriate for testing (e.g., "Choose best block"), or individual orders for each sample submitted. A Pathologist Block Selection Fee (ARUP test code 3002076) will be added to orders that utilize the first option. If multiple specimens are sent to ARUP without a request for pathologist block/slide selection or individual orders, they will be held until clarification is provided.


Slides: Ambient: 6 months (Must be stored in the dark); Refrigerated: 6 months (Must be stored in the dark); Frozen: Unacceptable
Paraffin Block:
Ambient: Indefinitely; Refrigerated: Indefinitely; Frozen: Unacceptable

Reference Interval

Interpretive Data

Refer to report. 

Compliance Category



This test code includes pathologist interpretation. At least 100 viable tumor cells are required for interpretation.

Hotline History


CPT Codes



Component Test Code* Component Chart Name LOINC
2012108 PD-L1 Client Block ID 94736-6
2013285 PDL1 Tissue Source 31208-2
2013286 Adequacy of Specimen
2013287 Tumor Proportion Score
2013288 PDL1 22C3 by IHC Result 55229-9
* Component test codes cannot be used to order tests. The information provided here is not sufficient for interface builds; for a complete test mix, please click the sidebar link to access the Interface Map.


  • Libtayo
  • Merck
  • PD-L1
  • PDL1
  • Pembro
  • Regeneron
PD-L1 22C3 IHC with Tumor Proportion Score (TPS) Interpretation, pembrolizumab (KEYTRUDA) and cemiplimab-rwlc (LIBTAYO)