[Optimization of rituximab dosing schedule in R-CHOP therapy for diffuse large B-cell lymphoma]

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma subtype, and nearly 70% of patients may be cured by administering R-CHOP therapy. However, R-CHOP is found to be inadequate in approximately one-third of the DLBCL cases, and refractory disease to R-CHOP is usually associated with a major cause of mortality. Therefore, it is essential to improve the efficacy of initial treatment in order to avoid unfavorable outcomes in patients with refractory DLBCL. In general, R-CHOP comprises of CHOP regimen that is repeated every 3 weeks and adding one-dose rituximab in each cycle. Although this combination method of rituximab with CHOP is effective and convenient, it does not contain enough scientific rationale and the schedule of rituximab administration has not been optimized. The pharmacokinetics of rituximab differs substantially among individuals and its serum half-life is approximately more than 500 hours; therefore, the peak concentration increases cumulatively by weekly infusion. A previous study revealed that patients with high blood concentration of rituximab showed higher response rate and longer progression-free survival. These findings suggest that the retention of higher levels of rituximab concentration and combination with chemotherapy during an early treatment period may bring about improvement of treatment effect. The HOVON group and Japan Clinical Oncology Group conducted randomized phase III studies to evaluate the efficacy of the dose-dense rituximab strategy for untreated DLBCL.