The role of HLA-G is extensively studied in cancer due to its inhibition of the immune response. Several polymorphisms in the HLA-G gene have been reported to significantly affect its expression. We, therefore, investigated whether functionally relevant HLA-G polymorphisms, HLA-G-725C/G/T, and HLA-G 14-base pair, have any influence on the susceptibility to diffuse large B-cell lymphoma (DLBCL) and its clinical course. The polymorphisms were genotyped in 207 previously untreated patients with DLBCL and 150 unrelated controls. A significant difference in genotype distribution of HLA-G polymorphic genotypes between the patients and controls was found. The frequencies of the HLA-G-725GG or the HLA-G-725GC genotype were lower, and those of the HLA-G ins/ins genotype were higher in the patients compared with the controls. Patients carrying the HLA-G-725CC genotype presented a higher probability of overall survival (OS) than subjects with other genotype combinations of HLA-G-725C/G/T (P = 0.003). The homozygous HLA-G del/del had a lower probability of OS than subjects carrying the HLA-G deletion/insertion (del/ins) or the HLA-G ins/ins genotype (P = 0.009). Two HLA-G genotype-based risk groups were defined according to the genotype distribution. The high-risk (HR) group presented a shorter OS than low-risk (LR) patients (P = 0.001). In a multivariate analysis adjusted for International Prognostic Index (IPI) factors, both the intermediate high/high IPI-risk group (P < 0.0001) and the HR genotype group (P = 0.004) independently increased the risk of death. This is the first study indicating an important role of HLA-G polymorphisms for the clinical course of DLBCL. The potential influence of HLA-G polymorphisms on the susceptibilityto DLBCL thus deserves further study.

The expression of human leukocyte antigen-G (HLA-G) and HLA class II protein was studied by immunohistochemical staining of lymph nodes from 148 patients with diffuse large B-cell lymphoma (DLBCL) and related to the clinical course of the disease. Negative HLA-G expression was associated with a lower probability of achieving a complete remission (p = 0.04). Patients with negative HLA-G expression tended towards a lower 3-year overall survival (OS) rate compared to those with positive expression of HLA-G (p = 0.08). When restricting the analysis to patients receiving chemotherapy with rituximab, the estimated 3-year OS rate of patients with positive HLA-G expression was 73.3 % compared with 47.5 % (p = 0.03) in those with negative expression. Patients with negative HLA class II expression presented a lower 3-year OS rate compared to subjects with positive expression (p = 0.04). The loss of HLA class II expression (p = 0.05) and belonging to the intermediate high/high IPI risk group (p = 0.001) independently increased the risk of death. HLA class II expression also retained its prognostic value in patients receiving rituximab; the 3-year OS rate was 65.3 % in patients with positive HLA class II expression versus 29.6 % (p = 0.04) in subjects that had loss of HLA class II expression. To our knowledge, for the first time, the expression of HLA-G protein in DLBCL and its association with the clinical course of the disease was demonstrated. Moreover, the link between losing HLA class II protein expression and poor survival of patients treated with immunochemotherapy was confirmed.

IKZF1 encodes a transcription factor involved in B-cell maturation and differentiation. We genotyped 218 diffuse large B-cell lymphoma (DLBCL) patients and 715 unrelated controls using a TaqMan allelic discrimination assay. No statistical difference was observed in the genotype distribution of the IKZF1 rs4132601 polymorphism between DLBCL patients and controls. However, the 2-year PFS rate of patients with the IKZF1 TT genotype was 54.3% compared to 68.6% in those with the IKZF1 G+ genotypes. Moreover, the IKZF1 rs4132601 polymorphism retained its independent prognostic impact on PFS. A more pronounced effect of the IKZF1 TT genotype on PFS was detected in patients with low/intermediate low IPI-risk group. When analysis was restricted to patients with GCB-type pattern, those with the IKZF1 TT genotype achieved a lower 5-year OS rate than the patients with the IKZF1 G+ genotypes (19.6 vs. 56%). This study provides the first evidence for the association of IKZF1 variants with DLBCL outcome.

There is growing evidence that genetic variations in the human leukocyte antigen (HLA) genes play a role in the etiology and clinical course of NHL. HLA-G belongs to the non-classical class I major histocompatibility complex-1 (MHC-I) polymorphic molecules and due to its suppression of immune response it is able to facilitate tumor escape from immunosurveillance. Several polymorphisms in the HLA-G gene have been reported to significantly affect its expression. Therefore, we investigated whether functionally relevant HLA-G polymorphisms, HLA-G-725C/G/T and HLA-G 14-bp, have any influence on the susceptibility to, and clinical course of, diffuse large B-cell lymphoma (DLBCL). The polymorphisms were genotyped in 207 previously untreated patients with DLBCL and 150 unrelated controls. A significant difference in genotype distribution of HLA-G polymorphic genotypes between the patients and controls was found. The frequencies of the HLA-G-725GG or the HLA-G-725GC genotype were lower (OR [odds ratio]= 0.47, P= 0.004), and those of the HLA-G ins/ins genotype were higher (OR= 2.08, P= 0.004) in the patients compared to controls. In univariate logistic regression analysis, neither HLA-G -725C/G/T nor HLA-G 14-bp influenced the probability of achieving a remission. There was no influence of HLA-G polymorphisms on the probability of progression-free survival (PFS). However, the patients carrying the HLA-G-725CC genotype presented a higher probability of 5-year overall survival (OS) than subjects with other genotype combinations of HLA-G-725C/G/T (38.2% vs 21.7%, P=0.003, log-rank test). The estimated 5-year OS among the homozygotes HLA-G del/del was 18.9% compared to the 35.3% in the subjects carrying the HLA-G del/ins or the 46.1% in those with the HLA-G ins/ins genotype (P=0.009, log-rank test). In a multivariate Cox analysis adjusted for IPI factors, we found that both the HLA-G -725C/G/T polymorphism (P= 0.01) and the IPI (P< 0.0001) retained their independent prognostic impact on OS The influence of the particular genotypes of the HLA-G -725C/G/T and the HLA-G 14-bp polymorphism on OS allow us to single out two HLA-G genotype-based risk groups. The low risk (LR) group included the patients carrying the HLA-G -725CC genotype and the HLA-G del/ins or the HLA-G ins/ins genotype. In contrast, the high risk (HR) group comprised those patients with other HLA-G genotype combinations. It is worth noting that the estimated 5-year OS rate of patients with LR genotypes was 42.7% in comparison to the 19.3% (P= 0.001, log-rank test) in patients with HR genotypes. An additional multivariate analysis, including HLA-G genotype-based risk groups and the IPI, revealed that both the intermediate high/high IPI risk group (P< 0.0001) and the HR genotype group (P= 0.004) independently increased the risk of death. This is the first study indicating an important role for HLA-G polymorphisms in the clinical course of DLBCL. The potential influence of HLA-G polymorphisms on the susceptibility to DLBCL deserves further study. It would seem that the inherited ability of the host to suppress anti-tumor immune response and then facilitate tumor escape from immunosurveillance might contribute to the pathogenesis and prognosis of B-cell malignancies. Disclosures Robak: MorphoSys AG: Research Funding.