Abstract 1189: Revisiting immune exhaustion in Hodgkin’s lymphoma

Abstract Clinical successes with immune check-point blockers have demonstrated the potency of the immune system in controlling cancers, most strikingly in Hodgkin lymphoma (HL), where overall response rates to PD1/L1 inhibitors approach 90%. Complete or durable responses, however, are uncommon, therefore targeting the PD1/L1 axis alone is not sufficient. Recent work analyzing the spatial arrangement of PD1 and PDL1 expressing cells has given us new insight into the mechanism of action of PD1/L1 inhibitors, however this work limited itself to studying a single check point marker on a subset of cells. We hypothesize that comprehensive profiling of the frequency and spatial arrangement of immune cells in the Hodgkin lymphoma tumor immune microenvironment (TME) will provide new insights into the mechanism of checkpoint blockers and identify novel targets for immune therapy. Until now, multiparameter spatial analysis of the immune microenvironment was limited by technical challenges. Flow and mass cytometry are able to identify immune subsets of interest but spatial information is lost. Multiplex tissue imaging methods are limited to 6-8 simultaneous markers and cannot capture the full complexity of the immune phenotypes. The Fluidigm Hyperion imaging mass cytometry (IMC) system combines a CyTOF mass cytometer with a laser ablation system allowing for 40+ parameter simultaneous immunophenotyping on a single slide of FFPE tissue, with sub-cellular resolution. We have developed a panel of 34 antibodies that allow for comprehensive characterization of CD4, CD8 and myeloid cells components in the TME of Hodgkin lymphoma using IMC. Here we report on our spatial analysis of TIM3 and LAG3 expressing CD4+ lymphocytes. Our data suggests LAG3+CD4+ and TIM3+CD4+ lymphocytes had shorter mean nearest distance to PDL1+Hodgkin Reed-Sternberg (HRS) cells upon comparison to PDL1- HRS cells (t-test, p=1.703e-08,p=1.126e-14). Future studies should explore multiple exhausted marker models that seeks to further understand the presence of simultaneous exhaustion signals in the niche environment. These data suggest that therapies that target TIM3 and/or LAG3 should be tested in Hodgkin Lymphoma and that spatial analysis of immune subsets by IMC should be explored as selective and pharmacodynamic biomarkers. Citation Format: Anthony R. Colombo, Monirath Hav, Erik Gerdtsson, Jose Bisnesto-Villasboas, Stephen Ansell, James Hicks, Peter Kuhn, Akil Merchant. Revisiting immune exhaustion in Hodgkin’s lymphoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1189.