Th1/2 Immune Response Signature Predicts Outcome after Dose-Dense Immunochemotherapy in Patients with High Risk Diffuse Large B-Cell Lymphoma - Results from Nordic Lymphoma Group Trials

Introduction: Despite better therapeutic options and improved survival of diffuse large B-cell lymphoma (DLBCL), 30-40% of the patients still relapse and have dismal prognosis. Recently, the impact of genomic aberrations, allowing lymphoma cells to escape immune recognition on DLBCL pathogenesis has been recognized. However, whether immune related signatures could be used as determinants for treatment outcome has not been rigorously evaluated. Here, our aim was to elucidate the immunologic characteristics of the tumor microenvironment, and associate the findings with outcome in patients with high-risk DLBCL.

Patients and methods: We specifically examined gene expression in the tumor microenvironment, using RNA isolated from formalin fixed paraffin-embedded (FFPE) tumor samples from 81 patients with DLBCL. Gene expression analysis was conducted on the NanoString nCounter gene expression platform using a 770-gene PanCancer Immune panel. The predictive impact of the gene expression signatures was assessed using a cohort of 65 high risk DLBCL patients enrolled in the Nordic CHIC trial (Leppä et al., 2016). The findings were validated using exon array data from an independent cohort of 38 high risk DLBCL patients treated in the Nordic CRY-04 trial (Holte et al., 2013; Leivonen et al., 2017a). In both trials, the patients received dose-dense immunochemotherapy (R-CHOEP-14) and systemic central nervous system prophylaxis (HD-Mtx and HD-Ara-C).

Results: Unsupervised hierarchical clustering revealed three major clusters of genes with differential expression between the patients. The clusters were enriched for the genes related to focal adhesion and extracellular matrix (ECM) receptor interactions (eg. COL3A1, ITGA, ITGB, VEGFC, VEGFA, PDGFRB, PDGFC, FN1 ), T/NK-cell signaling (eg. ICAM1, CD3, CD4, CD8 GZMB, ITGB2 ), and type 1/2 immune responses (eg. IL4, IFNL1, IFNL2, IL13, IL24 ). Interestingly, type 1/2 immune response signature correlated with survival. In the CHIC cohort, the group of patients (n=10) with high expression of type 1/2 immune response signature genes had a 4-year PFS of 60% in comparison to 91% for those (n=55) with low expression ( p = 0.021). The corresponding 4 y OS rates were 64% vs 90% (p=ns). The risk of progression was 4.0 fold higher for the patients with high expression of type 1/2 immune response signature genes (95% CI 1.120-14.280, p=0.033). No differences were observed in sex, age, stage, IPI scores, or molecular subgroups between the low and high type 1/2 immune response subgroups. The prognostic impact of the signature was confirmed in the CRY-04 exon array cohort (4-y PFS; 46% vs 80%, p = 0.021, 4-y OS 62% vs 88%; p = 0.014). In the CRY-04 cohort, the risk of progression was 3.6 fold (95% CI 1.13-11.20, p=0.030) and death 4.8 fold (95% CI 1.20-19.26, p=0.027) higher for the group of patients with high expression of the type 1/2 immune response signature genes. In contrast to our data on primary testicular lymphomas (PTLs) (Leivonen et al., 2017b), T/NK cell signature did not correlate with outcome in either of the trial cohorts. Correspondingly, type 1/2 immune signature was not associated with outcome in the cohorts of PTL or DLBCL patients treated with conventional R-CHOP regimen.

Conclusion: Our data suggest that immune related signatures exhibit treatment-specific roles in diffuse large B-cell lymphoma. For the high risk DLBCL patients treated with dose-dense immunochemotherapy, high expression of type 1/2 immune response signature genes predicts a poor outcome. A detailed characterization of immune cell composition in the tumor microenvironment and its impact on survival is ongoing.