Kristiina Karihtala1,2, Suvi-Katri Leivonen1,2, Teijo Pellinen3, Oscar Brück4, Marja-Liisa Karjalainen-Lindsberg5, Satu Mustjoki4, Sirpa Leppä1,2
1 Research Program Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland, 2 Department of Oncology, Comprehensive Cancer Center, Helsinki University Hospital, Helsinki, Finland, 3 Institute for Molecular Medicine Finland (FIMM), Helsinki, Finland, 4 Hematology Research Unit Helsinki, Department of Clinical Chemistry and Hematology, University of Helsinki, Helsinki, Finland, 5 Department of Pathology, Helsinki University Hospital, Helsinki, Finland
Background: Tumor microenvironment (TME) and immune escape have a major impact on pathogenesis and survival in classical Hodgkin lymphoma (cHL). Particularly, high tumor-associated macrophage (TAM) content associates with poor outcome. Here, we aimed to identify TAMs and their immunophenotypes, and translate the findings into survival of cHL patients.
Experimental Design: We collected clinical data and formalin-fixated paraffin-embedded tumor samples from 134 cHL patients, and used multiplex immunohistochemistry (mIHC) and computerized image analysis to examine macrophage markers (CD68 and CD163), Hodgkin Reed-Sternberg (HRS) cell marker (CD30), programmed cell death ligand 1 (PD-L1), and indoleamine 2,3-dioxygenase 1 (IDO-1). CD68, CD163, CD274 (PD-L1), and IDO-1 mRNA levels were measured utilizing the Nanostring platform.
Results: The male/female ratio was 46%/54%, and the median age 30 years (range 16–83). Thirty-two (24%) patients were 45 years or older, 105 (78%) had nodular sclerosis subtype, and 76 (57%) stage IIB-IV disease. At the median follow-up of 54 months (range 7 to 229), 31 (23%) patients had relapsed and 11 (8%) died, 7 (64%) of the deaths being related to cHL. Five-year recurrence free survival (RFS), disease-specific survival (DSS) and overall survival (OS) rates were 78%, 93% and 90%, respectively.
CD274 mRNA levels correlated with CD68 (rho = 0.688, p < 0.001) and CD163 expression (rho = 0.362, p = 0.001), and translated into poor RFS (p = 0.038). Likewise, IDO-1 mRNA levels correlated with CD68 (rho = 0.386, p < 0.001), and poor RFS (p = 0.018). A high agreement with the gene expression and the mIHC data was found when analyzing the quantities of CD68+ (rho = 0.491, p < 0.001), CD163+ (rho = 0.768, p < 0.001), PD-L1+ (rho = 0.688, p < 0.001), and IDO-1+ cells (rho = 0.745, p < 0.001). Consistent with the mRNA data, PD-L1+ and IDO+ cells associated with poor RFS, DSS, and OS (Table 1). The fraction of PD-L1+ HRS cells was 46% (median 47%, range 0–91%) and a large proportion of TAMs were PD-L1+ (mean 30%, median 22%, range 0–94%) or IDO+ (mean 10%, median 5,5%, range 0–73%). High PD-L1+ and IDO+ TAM proportions translated into poor survival (Table 1). In contrast, PD-L1+ HRS cells, PD-L1- or IDO- TAMs did not associate with the outcome.
Conclusions: The findings implicate PD-L1+ and IDO+ TAMs as prognostic factors for survival and as potential novel targets for immuno--oncology drugs in patients with cHL.