Therapeutic targets and microenvironment in sequential biopsies of classical Hodgkin lymphoma at diagnosis and relapse

Classical Hodgkin lymphomais dominated by the non-neoplastic microenvironment, while the neoplastic Hodgkin- Reed-Sternberg cellscompose only a minority of cells in the lymphoma tissue. Both the Hodgkin- Reed-Sternberg cellsdue to their expression of CD30and PD-L1and the microenvironment with abundant T cells and expression of PD1 are specifically targeted by new treatment concepts. We aimed to understand the dynamics of therapeutic targets in patients treated with conventional chemotherapy. We analyzed sequential biopsy specimens obtained at diagnosis and at relapse from the same patient for morphology, immunophenotype, and microenvironmental components. The morphological subtype changed between primary and relapse biopsy in 20% of cases. The immunophenotypewas stable with respect to CD30, CD3, and LMP1 but variable with respect to CD15and CD20expression. Gene expression revealed 8 upregulated and 20 downregulated genes at relapse (p ≤ 0.05) with a consistent logarithmic fold changedirection in at least 75% of all cases. For PD1, we found discrepant results between gene expression analysis (decrease at relapse) and number of PD1-positive cells assessed by immunohistochemistry (unchanged at relapse). PD-L1in the neoplastic cells appeared unchanged between primary diagnosis and relapse. The expression of the therapeutic targets CD30, PD1, and PD-L1can reliably be assessed in tumor specimen at first diagnosis and is unchanged under conventional chemotherapy.