The Tumor Microenvironment (TME) in classical Hodgkin lymphoma (HL) contains abundant immune cells and only few neoplastic Hodgkin and Reed-Sternberg cells (HRSC). We analyzed the T-cell receptor (TCR) repertoire to detect T-cell expansion in the TME and blood. In contrast to solid cancer tissue, T-cells in the TME of HL are highly polyclonal at first diagnosis and show only minor clonal expansion during anti-PD1 immune check-point blockade (ICB). At relapse and during ICB, pre-amplified T-cell populations increase in the TME of solid cancers but much less in HL. In contrast, T-cell populations in the peripheral blood of HL patients display higher clonality than healthy controls reaching clonality levels comparable to solid cancer and or CMV-infection. However, these pre-amplified blood T-cell populations show only minor additional clonal expansion during ICB. Moreover, blood-derived T-cells do not repopulate the TME of HL at relapse or during ICB to the same extent as observed in solid cancers. Thus, the T-cell repertoire in the TME of HL appears unique in its polyclonality and the exclusion of clonally expanded T-cells from the peripheral blood. Exclusion of clonally expanded tumor-specific T-cells from the TME may present a novel and potentially targetable mechanism of immune evasion in HL.
Nicole Seifert, Sarah Reinke, Johanna Grund, Berit Müller-Meinhard, Julia Richter, Thorsten Heilmann, Hans Schlößer, Michaela Biehl-Kotrova, Monika Brüggemann, Peter Borchmann, Paul J. Bröckelmann, Michael Altenbuchinger, Wolfram Klapper