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PD-L1 IHC BIOMARKER
Assay Purpose:
Diagnosis: Gastric, gastroesophageal, and esophageal adenocarcinoma, and esophageal squamous cell carcinoma
Drugs: Pembrolizumab (Merck) and Nivolumab (Bristol Myers Squibb)
Diagnostic test: PDL1 Dako 22C3 PharmDX
Result: CPS < 1 OR CPS >= 1 and < 5 OR CPS >= 5 and < 10 OR CPS >= 10 OR Inadequate
Interpretation: Combined Proportion Score (CPS) - Negative (< 1), other results are interpreted with available biological and clinical parameters.
Performed on block ***
Batch control: Adequate; on slide controls: Adequate.
Disclaimer: The above results represent an extension of existing clinical trial guidance, derived from meta-analytical data, and were provided at the request of the Alberta GI Oncology Group. It remains the sole responsibility of the treating oncologist to interpret these results in the context of clinical decision-making and to determine eligibility for immunotherapy in patients with upper gastrointestinal neoplasms. The laboratory’s role is limited to the provision of TPS and/or CPS results as reported above. The laboratory assumes no responsibility for clinical interpretation, therapeutic decision-making, or patient management based on these results. PD-L1 22C3 pharm Dx was validated with tissue fixed in 10% neutral buffered formalin (NBF) for 12 to 72 hours. The method is not fully validated for shorter or longer fixation in NBF, other fixatives, extended ischemic time, treatment of tissue with microwaves or decalcification. In the context of upper GI neoplasms 22C3 was considered interchangeable with the PD-L1 assay 28-8 (see reference below). Batch control includes 2 pelleted, formalin fixed paraffin embedded cell lines: NCI-H226 with moderate PD-L1 protein expression and MCF-7 with negative PD-L1 protein expression. On slide controls include one piece of tonsil (with expected PD-L1 staining positive in immune cells and keratinocytes) and one piece of liver (with expected PD-L1 staining negative in hepatocytes). Furthermore, for specimen adequacy, this assessment should only rely on tissue showing invasive carcinoma and must include a minimum of 100 malignant cells.
Reference: PD-L1 expression in gastric cancer: interchangeability of 22C3 and 28-8 pharmDX assays for responses to immunotherapy. Modern Pathology. 2021;34(9):1719-1727.
Test ID: PDL1UPPERGIMARCH2026