Evaluation of programmed death ligand 1 expression in cytology to determine eligibility for immune checkpoint inhibitor therapy in patients with head and neck squamous cell carcinoma

Abstract

BACKGROUND:Immune checkpoint inhibitors targeting the programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway have recently emerged as a frontline treatment for head and neck squamous cell carcinoma (HNSCC). The evaluation of PD-L1 expression by immunohistochemistry in histologic samples is used to determine the eligibility of patients with HNSCC for immunotherapy. Patients with newly diagnosed HNSCC are frequently diagnosed by fine-needle aspiration (FNA) of lymph nodes with metastatic disease. However, the evaluation of PD-L1 expression with the proposed combined positive score (CPS) has not been well established in cytology specimens. METHODS: This study retrospectively identified 21 HNSCC patients with a known PD-L1 status from histologic specimens and matched FNA specimens with tumor cells on cell blocks (CBs). The CB sections were stained with a PD-L1 antibody (22C3 clone). All cases were scored with CPS and the tumor proportion score (TPS). RESULTS: The data showed substantial concordance between cytologic and histologic specimens for CPS (agreement, 76.2%; κ = 0.607) and TPS (agreement, 76.2%; κ = 0.607). With histology used as a reference standard, the positive predictive value was 100% for both CPS and TPS, whereas the negative predictive value was 57.1% for CPS assessments and 50% for TPS assessments. CONCLUSIONS: PD-L1 expression in HNSCC cytology samples has high concordance with paired histologic samples. PD-L1 CPS evaluation is feasible in HNSCC cytology CBs and can act as a surrogate for determining eligibility for immunotherapy in cases in which a histologic specimen is not readily available.

Atlas of PD-L1 for Pathologists: Indications, Scores, Diagnostic Platforms and Reporting Systems

“…As opposed to TPS assessment, the evaluation of PD-L1 expression using CPS has not been well established on cytological material, mainly because of challenges in identifying tumor-associated immune cells in the absence of tissue architecture. Although still limited, the literature data showed that the evaluation of CPS on cytological samples is feasible, especially in the case of positive PD-L1 expression [ 93 , 94 ].…”

Roles of Major RNA Adenosine Modifications in Head and Neck Squamous Cell Carcinoma

“…Meanwhile, Liu et al . proposed that the expression of PD-L1 in HNSCC cytology samples is highly consistent with matched histological samples ( Liu et al, 2021 ). Lee et al also believe that ICIs show good anti-tumor activity against R/M HNSCC ( Lee et al, 2021 ).…”

“…Blocking TIGIT/CD155 combined with PD-L1 monoclonal antibody treatment can significantly improve the efficacy of HNSCC (Mao et al, 2021). Meanwhile, Liu et al proposed that the expression of PD-L1 in HNSCC cytology samples is highly consistent with matched histological samples (Liu et al, 2021). Lee et al also believe that ICIs show good anti-tumor activity against R/M HNSCC (Lee et al, 2021).…”

PD‐L1 immunohistochemical testing: A review with reference to cytology specimens

“…The majority of the specimens in our review were non‐small cell lung adenocarcinomas, the review studies contained 23 melanomas, 9 21 squamous cell carcinomas of the head and neck, 10 24 cases of ovarian adenocarcinoma, 11 39 pancreatic carcinomas, 12 and 79 squamous cell carcinomas of the lung 13 …”