PD-L1 IHC BIOMARKER
Assay Purpose:
Diagnostic : Resectable, Locally Advanced Head and Neck Squamous Cell Carcinoma (HNSCC) – Neoadjuvant/Adjuvant Treatment Setting
Drug: Pembrolizumab (Merck)
Diagnostic test: PDL1 Dako 22C3 pharmDX
Result: Positive CPS >= 1 OR Negative CPS < 1 OR Inadequate
Interpretation: Combined Proportion Score (CPS) - Negative (< 1), Positive (>= 1)
Performed on block ***
Batch control: Adequate; on slide controls: Adequate
Disclaimer: Please note the PD-L1 IHC (22C3 pharm Dx) with the combined positive score (CPS) utilized herein has been developed for use of Pembrolizumab in resectable locally advanced head and neck squamous cell carcinoma – Neoadjuvant/Adjuvant Treatment Setting (KEYNOTE-689, NCT03765918). This assay is not interchangeable with other PD-L1 assays. 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. 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 (except rare instances, should not be performed on cytological specimen) and must include a minimum of 100 malignant cells.
Note: While clinical benefit was observed across all CPS groups, regulatory approval by both the FDA and Health Canada currently requires PD-L1 expression with a CPS ≥ 1 to qualify for pembrolizumab treatment in this setting.
Reference: Uppaluri R, Haddad RI, Tao Y, et al. Neoadjuvant and Adjuvant Pembrolizumab in Locally Advanced Head and Neck Cancer. N Engl J Med.* 2025 Jul 3;393(1):23–35. doi:10.1056/NEJMoa2406823.
Test ID: PDL1HNSCCNEOADPEMBRO