HLA-G+3027 polymorphism is associated with tumor relapse in pediatric Hodgkin's lymphoma

Abstract

In this study, we tested whether polymorphisms in human leukocyte antigen G (HLA-G) were associated with event-free survival (EFS) in pediatric Hodgkin's lymphoma (HL). We evaluated the association of HLA-G 3'-UTR polymorphisms with EFS in 113 pediatric HL patients treated using the AIEOP LH-2004 protocol. Patients with the +3027-C/A genotype (rs17179101, UTR-7 haplotype) showed lower EFS than those with the +3027-C/C genotype (HR= 3.23, 95%CI: 0.99-10.54, P=0.012). Female patients and systemic B symptomatic patients with the HLA-G +3027 polymorphism showed lower EFS. Multivariate analysis showed that the +3027-A polymorphism (HR 3.17, 95%CI 1.16-8.66, P=0.025) was an independent prognostic factor. Immunohistochemical analysis showed that HL cells from patients with the +3027-C/A genotype did not express HLA-G. Moreover, HLA-G +3027 polymorphism improved EFS prediction when added to the algorithm for therapeutic group classification of pediatric HL patients. Our findings suggest HLA-G +3027 polymorphism is a prognostic marker in pediatric HL patients undergoing treatment according to LH-2004 protocol.

Keywords: +3027 C/A genotype; 3’UTR polymorphism; HLA-G; event-free survival; pediatric hodgkin lymphoma.

Figure 1. Kaplan-Meier survival analysis of +3027C/A HLA-G polymorphisms

Kaplan Meier survival curves show 72.3% and 34% EFS for patients with the +3027 C/C and C/A variant, respectively (C/A vs. C/C, HR=3.23, 95% CI 0.99-10.54; P=0.012). The solitary patient with A/A genotype was excluded from the analysis.

Figure 2. Cox regression analysis of event-free survival based on gender and systemic symptoms

Cox regression analysis shows patients carrying +3027 HLA-G polymorphism show lower EFS in (A) female and (B) systemic B symptomatic patients.

Figure 3. Kaplan Meier survival analysis comparing algorithms based on the HLA-G genotype and AIEOP LH-2004 risk score classification

(A) Kaplan Meiersurvival curves based on HLA-G +3027 algorithm is shown. Patients were divided into 2 groups based on their HLA-G +3027 genotype (C/C and C/A) and further divided into 3 groups based the AIEOP LH-2004 therapeutic risk score (GR). Since the GR1 and GR2 groups with the +3027 C/A variant included less than 2 patients, GR1, GR2 and GR3 groups with the +3027 C/A variant were merged to form a unique GR123-C/A group. (B) Kaplan Meier survival curves based on the AIEOP LH-2004 risk score for therapeutic response (GR) in pediatric HL patients. Note: Criteria for the AIEOP LH2004 therapeutic group (GR) classification are in the methods section.

Figure 4. Comparison of the risk values based on AIEOP LH-2004 group therapy protocol and HLA-G +3027 algorithm

Kaplan-Meier survival analysis show hazard ratios (HR) for GR1, GR2 and GR3 groups based on AIEOP LH-2004 therapy and the HLA-G genetic groups, GR1,2,3-C/C and GR123-C/A based on our analysis. Note: GR1 and GR 1-C/C as reference categories; 95% CI confidence intervals are shown for event-free survival (EFS).

Figure 5. Overall survival in pediatric HL patients based on therapeutic grouping

Cox regression analysis showing OS in pediatric HL patients (n=113) based on therapeutic grouping (GR). As shown, GR1-C/C and GR2- C/C patients show higher EFS than GR3-C/C and GR123-C/A patients.

Figure 6. Immunohistochemical analysis of HLA-G protein expression in Reed-Sternberg cells in pediatric HL patients

Representative image shows immunohistochemical staining for HLA-G in a HL patient carrying the wild type C/C +3027 genotype. Formalin/PFA-fixed paraffin-embedded sections were stained with primary anti-HLA-G antibody (4H84). Lymphoma cells show strong membrane staining for HLAG. Note: Only 5 out of 25 patients analyzed were positive for HLA-G in our analysis.