Kristiina Karihtala1,2, Suvi-Katri Leivonen1,2, Teijo Pellinen3, Oscar Brück4, Marja-Liisa Karjalainen-Lindsberg5, Satu Mustjoki4, Sirpa Leppä1,2
1Research Program Unit, Faculty of Medicine, University of Helsinki, Helsinki, Finland,2Department of Oncology, Comprehensive Cancer Center, Helsinki University Hospital, Helsinki, Finland,3Institute for Molecular Medicine Finland (FIMM), Helsinki, Finland,4Hematology Research Unit Helsinki, Department of Clinical Chemistry and Hematology, University of Helsinki, Helsinki, Finland,5Department 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.