Is inactivation of O6-methylguanine DNA methyltransferase still a favorable prognostic factor of patients with diffuse large B-cell lymphoma in the era of R-CHOP chemotherapy?

The prognostic significance of O6-methylguanine DNA methyltransferase (MGMT) inactivation was evaluated in patients with diffuse large B-cell lymphoma (DLBCL) who received cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) in addition to rituximab. In this retrospective study, we used the methylation-specific polymerase chain reaction to investigate MGMT promoter methylation status and immunohistochemistry to evaluate MGMT expression in patients with DLBCL who received rituximab plus CHOP (R-CHOP) chemotherapy. No difference in patient characteristics, disease characteristics, response, or survival in patients with DLBCL who received front-line R-CHOP chemotherapy was observed according to MGMT methylation status and MGMT expression. On multivariate analysis, Grade 3-4 mucositis in the MGMT methylated group was significantly higher than that in the MGMT unmethylated group (hazard ratio (HR) 2.40, 95% CIs: 1.26-7.26, p = 0.014). This study demonstrated that inactivation of MGMT does not appear to play an important role in patients with DLBCL who received R-CHOP chemotherapy either with regard to the response rate or overall survival. Additionally, Grade 3-4 mucositis was found to be significantly related with inactivation of MGMT by a multivariate analysis.