Assay Purpose:
Diagnostic : Triple Negative Breast Cancer
Drug: Pembrolizumab (Merck)
Diagnostic test: PDL1 Dako 22C3 pharmDX
Result: Negative CPS < 10
Interpretation: Combined Positive Score (CPS) - Negative (< 10), *Positive (>= 10)
Batch control: Adequate; on slide controls: Adequate Disclaimer: indication: adult patients in combination with chemotherapy with locally recurrent unresectable or metastatic triple-negative breast cancer (TNBC), who have not received prior chemotherapy for metastatic disease and whose tumors express PD-L1 (Combined Positive Score [CPS] = 10) as determined by a validated test (Keynote-355). 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.
Reference: Cortes, J., Cescon, DW., et al. Pembrolizumab plus chemotherapy versus placebo plus chemotherapy for previously untreated locally recurrent inoperable or metastatic triple-negative breast cancer (KEYNOTE-355): a randomised, placebo-controlled, double-blind, phase 3 clinical trial https://ascopubs.org/doi/abs/10.1200/JCO.2020.38.15_suppl.1000