Concordance, Correlation, and Clinical Impact of Standardized PD-L1 and TIL Scoring in SCCHN

Expression of PD-L1, PD-L2, and inflammatory gene expression profile in locally advanced head and neck squamous cell carcinoma

BACKGROUND

The tumor immune microenvironment in cancer treatment response and resistance is of increasing interest. This retrospective study characterized and investigated programmed death-ligand 1 (PD-L1), PD-L2, and the immune gene expression signature and their association with clinical outcomes in locoregionally advanced head and neck squamous cell carcinoma (LA HNSCC).

PATIENTS AND METHODS

PD-L1 and PD-L2 expression on tumor and immune-infiltrating cells (positivity defined as combined positive score or immunohistochemistry proportion score >1) and T-cell-inflamed gene expression profile (TcellinfGEP) were evaluated in patients with LA HNSCC treated in South Korea from 2000 to 2015. Correlations among the three biomarkers and their associations with overall survival and recurrence-free survival were assessed.

RESULTS

Among 366 patients, 38.8% had human papillomavirus-positive disease. PD-L1-positive, PD-L2-positive, and high TcellinfGEP (≤-0.162) status were observed in 83.6%, 85.4%, and 73.2% of patients, respectively; 4.1% were posttreatment samples. Correlation between PD-L1 and PD-L2 scores was moderate (rSpearman = 0.50), and each biomarker was slightly less correlated with TcellinfGEP (0.41-0.45). PD-L1 expression and high TcellinfGEP status were associated with human papillomavirus positivity. Higher levels of all biomarkers were observed in oral cavity and oropharyngeal cancers compared with other HNSCC sites. In a multivariable analysis that simultaneously adjusted for all three biomarkers, only high TcellinfGEP was significantly associated with longer overall survival (adjusted hazard ratio, 0.57; 95% confidence interval 0.33-0.98) and recurrence-free survival (adjusted hazard ratio, 0.41; 95% confidence interval 0.23-0.74).

CONCLUSION

High TcellinfGEP status, but not PD-L1 or PD-L2 expression, was independently associated with longer survival in patients with LA HNSCC. Results may have implications for evaluating therapies targeting programmed cell death protein 1 (PD-1)/programmed death-ligand 1 (PD-L1) in HNSCC.

The prognostic value of tumor-infiltrating lymphocytes in head and neck squamous cell carcinoma: A systematic review and meta-analysis

Head and neck squamous cell carcinoma (HNSCC) is experiencing a rising incidence and mortality worldwide, emphasizing the need for reliable prognostic markers. Tumor-infiltrating lymphocytes (TILs) have emerged as a promising biomarker for predicting HNSCC prognosis, yet no systematic reviews have exclusively focused on hematoxylin and eosin (H&E)-stained formalin-fixed paraffin-embedded (FFPE) samples, which are routinely used in clinical practice. This systematic review and meta-analysis followed the PRISMA guidelines to examine the prognostic value of TILs in HNSCC using H&E-stained FFPE samples. Data were pooled from 43 studies, including 26 studies in a meta-analysis, analyzing 5037 HNSCC samples. We found that a high TIL count associated with a significantly improved overall survival (OS) (HR 0.47, 95 % CI 0.41-0.55, p < 0.0001), disease-free survival (DFS) (HR 0.55, 95 % CI 0.41-0.55, p < 0.0001), and disease-specific survival (DSS) (HR 0.58, 95 % CI 0.46-0.73, p < 0.0001). The heterogeneity was moderate for the pooled analysis (OS: I² = 40 %; DFS: I² = 39 %; DSS: I² = 51 %), but low for the subgroup analysis based on tumor site in oral, oropharyngeal, laryngeal, and nasopharyngeal cancer (OS and DFS: I² = 0-14 %). This review is the first to systematically evaluate TILs in HNSCC using H&E-stained samples, confirming their prognostic value. A high TIL count is associated with improved survival outcomes, suggesting their potential as prognostic biomarkers in clinical settings.

Standardized Digital Image Analysis of PD-L1 Expression in Head and Neck Squamous Cell Carcinoma Reveals Intra- and Inter-Sample Heterogeneity with Therapeutic Implications

For practical reasons, in many studies PD-L1 expression is measured by combined positive score (CPS) from a single tumor sample. This does not reflect the heterogeneity of PD-L1 expression in head and neck squamous cell carcinoma (HNSCC). We investigated the extent and relevance of PD-L1 expression heterogeneity in HNSCC analyzing primary tumors and recurrences (LRs), as well as metastases. Tumor tissue from 200 HNSCC patients was immunohistochemically stained for PD-L1 and analyzed using image-analysis software QuPath v3.4 with multiple specimens per patient. CPS was ≥20 in 25.6% of primary tumors. Intra-tumoral heterogeneity led to a therapeutically relevant underestimation of PD-L1 expression in 28.7% of patients, when only one specimen per patient was analyzed. Inter-tumoral differences in PD-L1 expression between primary tumors and lymph node metastasis (LNM) or LR occurred in 44.4% and 61.5% (CPS) and in 40.6% and 50% of cases (TPS). Overall survival was increased in patients with CPS ≥ 1 vs. CPS < 1 in primary tumors and LNM (hazard ratio: 0.46 and 0.35; p < 0.005); CPS in LR was not prognostic. Our analysis shows clinically relevant intra- and inter-sample heterogeneity of PD-L1 expression in HNSCC. To account for heterogeneity and improve patient selection for immunotherapy, multiple sample analyses should be performed, particularly in patients with CPS/TPS < 1.

Assessing PD-L1 Expression in Head and Neck Squamous Cell Carcinoma: Trials and Tribulations

Immune checkpoint inhibitors have improved the outcome of patients diagnosed with inoperable recurrent or metastatic head and neck squamous cell carcinoma. However, as only a subset of head and neck cancer patients benefit from this treatment, biomarkers predicting treatment response help guide physicians in their clinical decision-making. PD-L1 expression assessed by immunohistochemistry is the single most clinically relevant biomarker predicting response to PD-1-blocking antibodies. Here, we discuss in which clinical context assessment of PD-L1 expression is instrumental for the choice of therapy, how pathologists score it, and how it affects the approval of anti-PD-1 antibodies. Furthermore, we discuss the heterogeneity of PD-L1 expression and review technical aspects of determining this prominent biomarker-knowledge that might influence clinical decision-making.

Reliability of gene-expression profiling from tumor biopsy for refining neoadjuvant strategies in patients with head and neck squamous cell carcinoma

While recent clinical trials evaluating neoadjuvant immune checkpoint inhibitors showed promising results in a subset of patients with head and neck squamous cell carcinomas (HNSCC), there is a need for the identification of robust biomarkers in tumor biopsies to improve patient selection. This context suggests unravelling transcriptomic heterogeneity between untreated paired samples from same patient with HNSCC. Based on previous studies and the analysis of publicly available gene expression profiles of paired tumor biopsies and surgical resection specimens, we discuss the reliability of tumor biopsy to capture the overall activation of targetable biological pathways in patients with HNSCC. Further studies investigating intratumor transcriptomic heterogeneity as well as the effect of sampling methods on gene expression are needed in patients with HNSCC, in order to develop innovative and relevant biomarker-driven neoadjuvant strategies.

Diagnostic Predictors of Immunotherapy Response in Head and Neck Squamous Cell Carcinoma

Programmed cell death ligand-1 (PD-L1) binds PD-1 on CD⁸⁺ lymphocytes, inhibiting their cytotoxic action. Its aberrant expression by head and neck squamous cell carcinoma (HNSCC) cells leads to immune escape. Pembrolizumab and nivolumab, two humanized monoclonal antibodies against PD-1, have been approved in HNSCC treatment, but ~60% of patients with recurrent or metastatic HNSCC fail to respond to immunotherapy and only 20 to 30% of treated patients have long-term benefits. The purpose of this review is to analyze all the fragmentary evidence present in the literature to identify what future diagnostic markers could be useful for predicting, together with PD-L1 CPS, the response to immunotherapy and its durability. We searched PubMed, Embase, and the Cochrane Register of Controlled Trials and we summarize the evidence collected in this review. We confirmed that PD-L1 CPS is a predictor of response to immunotherapy, but it should be measured across multiple biopsies and repeatedly over time. PD-L2, IFN-γ, EGFR, VEGF, TGF-β, TMB, blood TMB, CD73, TILs, alternative splicing, tumor microenvironment, and some macroscopic and radiological features are promising predictors worthy of further studies. Studies comparing predictors appear to give greater potency to TMB and CXCR9.

Prognostic and Predictive Relevance of Tumor-Infiltrating Lymphocytes in Squamous Cell Head-Neck Cancer Patients Treated with Radical Radiotherapy/Chemo-Radiotherapy

Microenvironmental conditions control the entrance and thriving of cytotoxic lymphocytes in tumors, allowing or preventing immune-mediated cancer cell death. We investigated the role of tumor-infiltrating lymphocyte (TIL) density in the outcome of radiotherapy in a series of squamous cell head−neck tumors (HNSCC). Moreover, we assessed the link between markers of hypoxia and TIL density. One-hundred twenty-one patients with HNSCC treated prospectively with radical radiotherapy/chemo-radiotherapy were analyzed. The assessment of TIL density was performed on hematoxylin and eosin biopsy sections before radiotherapy. TIL density ranged from 0.8 to 150 lymphocytes per ×40 optical field (median 27.5). Using the median value, patients were grouped into two categories of low and high TIL density. Early T-stage tumors had a significantly higher TIL density (p < 0.003), but we found no association with N-stage. Overexpression of HIF1α, HIF2α, and CA9 was significantly linked with poor infiltration by TILs (p < 0.03). A significant association of high TIL density with better disease-specific overall survival and improved locoregional relapse-free survival was noted (p = 0.008 and 0.02, respectively), which was also confirmed in multivariate analysis. It is concluded that HNSCC phenotypes that allow for the intratumoral accumulation of lymphocytes have a better outcome following radical radiotherapy/chemo-radiotherapy. Intratumoral-activated HIF- and CA9-related pathways characterize immunologically cold tumors and may be used as targets for therapeutic interventions.