Expression of Programmed Death Ligand 1 (PD-L1) in Classical Hodgkin Lymphoma- Study from a Tertiary Care Cancer...

Classical Hodgkin lymphoma (CHL) has an overall favourable prognosis. However, relapse/refractory CHL cases are associated with an unfavourable outcome. Targeted immunotherapy based on PD-1 and PD-L1 pathway inhibitors have shown improvement in the treatment of relapsed/refractory CHL cases. The objective of this study was to assess Programmed death ligand (PD-L1) expression before and after antineoplastic treatment in primary refractory (P/R) Classical Hodgkin lymphoma and relapsed/ refractory (R/R) Classical Hodgkin lymphoma cases. Slides and blocks of 30 paired biopsies of Classical Hodgkin Lymphoma cases during the five year study period which have been refractory or have relapsed post antineoplastic treatment were retrieved and reviewed. PD-L1 expression in Hodgkin Reed Sternberg (HRS) cells and micro environment (ME) at primary diagnosis and at relapse/refractory disease were analysed by staining with PD-L1 (SP263) antibody. Tumour cells and peritumoral microenvironment were evaluated separately. More than 5% expression with 2+/3+ intensity in HRS cells and/or in microenvironment were accepted as positive. In our patient population we found that the PD-L1 expression in relapse/refractory lymphoma biopsy in comparison to primary diagnosis biopsy remains largely unchanged in HRS cells and in the microenvironment. This stable expression of PD-L1 expression in paired biopsies suggests that PD-L1 inhibitors can be used as second line therapy in all relapsed Classical Hodgkin lymphoma patients without PD-L1 testing.