Correlation between expression of MCM6, a new proliferative marker, and treatment outcome in patients with Hodgkin's disease

Abstract

e19547 Background: MCM6 is a proliferative marker, which in contrary to Ki67, is involved in all cell cycle phases, including early G1. We evaluated MCM6 expression in Hodgkin's disease (HD) patients in order to find any correlation between MCM6 expression and treatment outcome. Methods: Formalin-fixed paraffin-embedded lymph node specimens of 55 patients with HD treated with ABVD regimen (± radiotherapy) were assessed for MCM6 expression by IHC. The percentage of nuclear positivity in RS and mononuclear Hodgkin cells was evaluated in each case. Clinical data, response to treatment and relapse rates were obtained from patients’ medical records. These data were analyzed by SPSS software. Results: Mean MCM6 expression was 80.7% (ranging 35%-99%) with no significant difference between histology subtypes. In univariate analysis, MCM6 expression was not statistically significant for B-symptoms (P=0.27), sex (P=0.91), stage (P=0.18) and response to treatment (P=0.53), but was significant for age (P=0.008) (≤23 vs >23 yrs old). The MCM6 mean expression between relapsed and non-relapsed groups was marginally significant (21% vs 29.4%, P=0.057). In multivariate analysis, we evaluated MCM6 expression, B-symptoms, stage, response rate and age for relapse. None of risk factors were statistically significant predictor for relapse, including MCM6 expression (P=0.238), however, were significant regarding to response (P<0.001) and stage (P=0.048). We divided patients in 4 quartiles based on their MCM6 expression (Q1<74.25%, N=13, Q2=74.26–85.5%, N=14, Q3=85.6–91.75%, N=13, Q4>91.75%, N=12). Relapse and PFS were not significantly different between these quartiles (P=0.27 and P=0.83, respectively). Conclusions: Our study on a limited number of patients revealed MCM6 is not a strong predictor for treatment outcome in patients with HD. Our findings can be possibly explained by early G1 arrest of tumor cells and the role of cytokine production in pathogenesis of HD. We believe determining the accurate predictive role of proliferative markers needs to be focused on the markers which are exclusively involved in S phase. No significant financial relationships to disclose.