Immunohistochemical assessment of the diagnostic utility of PD-L1: a preliminary analysis of anti-PD-L1 antibody (SP142) for lymphoproliferative diseases with tumour and nonmalignant Hodgkin/Reed-Sternberg (HRS)-like cells

Abstract

Aims

The programmed death 1 (PD1)/PD1 ligand (PD-L1) axis plays an important role in tumour cells escape from immune control. PD-L1 immunohistochemistry is a useful predictor of immunotherapy response, but is still not widely used in the diagnostic setting. Here we describe results using PD-L1 immunohistochemistry during routine diagnostics in lymphoma.

Methods and results

Ninety-one lymphoproliferative disease cases sharing tumour and nonmalignant Hodgkin/Reed-Sternberg (HRS)-like cells with and without Epstein-Barr virus (EBV) association were investigated by immunohistochemistry for PD-L1 (clone SP142). PD-L1 expression was present in more than 5% of tumour or nonmalignant HRS-like cells in 100% of EBV⁺ classical (C) Hodgkin lymphoma (HL) (n=10) and EBV-negative nodular sclerosis CHL (n=8); 40% of EBV⁺ diffuse large B-cell lymphoma, not otherwise specified (DLBCL-NOS) (n= 20); and 4% of nodal peripheral T-cell lymphoma of follicular helper T-cell type (PTCL-TFH) (n=22). In contrast, nodular lymphocyte predominant HL (n=4), lymphocyte-rich CHL (n=6), EBV⁺ hyperplasia (n=8), plasmablastic lymphoma (n= 3), and anaplastic lymphoma kinase-negative anaplastic large cell lymphoma (n=5) seldom exhibited PD-L1 in their large cells. Assessing PD-L1 positivity in tumour and nonmalignant large cells was helpful in differentiating between CHL vs nodal PTCL-TFH (P<0.0001) or EBV⁺ DLBCL-NOS (P=0.0052) and between EBV⁺ DLBCL-NOS vs nodal PTCL-TFH (P=0.0052), with PD-L1 expression indicating the first diagnosis in each of those sets.

Conclusion

Immunohistochemical evaluation of PD-L1 expression in tumour and nonmalignant HRS-like large cells may be useful for assessing either immune escape or immunodeficiency in their pathogenesis.

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