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    Volume 26, Issue 6

    PD-L1 protein expression patterns in renal cell carcinoma based on conventional and digitized evaluation

    Updated:2 Mins Read

    Paraskevi Tziakou1*, Grigorios Theodoropoulos2*, Evangelos Tsiambas3,4*, Gerasimos Kollaitis2, Eirini Thymara4, Nikolaos Kavantzas4, Andreas C. Lazaris4

    1Department of Pathology, “Thriasio” General Hospital of Elefsina, Elefsina, Greece.

    2Department of Urology, Athens General Hospital “Elpis”, Athens, Greece.

    3Department of Cytology, 417 VA (NIMTS), Athens, Greece.

    4Department of Pathology, Medical School, National and Kapodistrian University of Athens, Athens, Greece.

    *Authors equally contributed

    Summary

    Purpose: Programmed cell death ligand-1 (PD-L1), also known as CD274 (cytogenetic band: 9p24.1), is expressed predominantly in most hematopoietic cells and also in epithelial cells. Our aim was to evaluate PD-L1 protein expression in renal cell carcinoma (RCC) tissues by comparatively implementing conventional and also digitized assays.

    Methods: We used 100 archival, formalin-fixed and paraffin-embedded RCC tissue specimens, including 75 histologically confirmed clear cell RCC, 13 papillary RCCs, and 12 chromophobe RCC. Immunohistochemistry was performed implementing an anti- PD-L1 antibody. Conventional (Tumor Proportion Score (TPS)-qualitative) and also digital image analysis (DIA-quantitative) assays were applied for evaluating the corresponding protein expression levels.

    Results: According to DIA, negative or loss of PD-L1 expression was observed in 92 cases (92%), in 2 (2%) of them moderate levels were detected, whereas 6 (6%) were characterized by strong (high) expression. Based on the TPS evaluation, 8 (8%) cases were characterized as positive, whereas the rest of them (92/92%) as negative. Interestingly, kappa analysis revealed a high level of overall correlation between qualitative and quantitative based assays (kappa=0.94).

    Conclusions: PD-L1 overexpression is detected in low rates in RCC, especially in the clear cell carcinoma histological variety. Implementation of digitized (staining intensity) analytical methods provides an objective and accurate approach matching with the conventional protein expression evaluation and categorization as positive/negative cases.

    Key words: renal carcinoma, PD-L1, protein, image analysis, immunotherapy.

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