Pharmacokinetic profile and first preliminary clinical evaluation of bendamustine in Taiwanese patients with heavily pretreated indolent B-cell non-Hodgkin lymphoma and mantle cell lymphoma

Prior studies found bendamustine is efficacious in patients with indolent B-cell non-Hodgkin lymphoma (NHL). To date, no studies have reported the efficacy of bendamustine in a Chinese population. This multicentre phase II trial evaluated the pharmacokinetics (PK), safety and efficacy of bendamustine monotherapy in Chinese patients in Taiwan with pretreated indolent B-cell NHL or mantle cell lymphoma (MCL). For PK assessments, patients were randomized (n=16; 11 with indolent B-cell NHL and five with MCL) to 90 or 120mg/m² of bendamustine for the first cycle. Plasma levels of bendamustine and its two metabolites were analyzed. For efficacy and safety evaluations, bendamustine 120mg/m² was given to all patients every 3weeks starting at cycle 2 for a minimum of a total of six cycles. The median age of patients was 61.7years, and the majority were men (75%). The median number of prior treatments was 4 (range, 1-9 regimens), and all patients were previously treated with rituximab. Bendamustine plasma concentration peaked near the end of infusion and was rapidly eliminated with a mean elimination half-life (t_1/2) of 0.67-0.8h. Of the evaluable patients (n=14), the overall response rate was 78.6%, including 7.2% of patients having a complete response. Mean progression-free survival was 27.5weeks. The most common grade 3-4 adverse events were leucopenia (56.3%), neutropenia (56.3%) and thrombocytopenia (25%). In conclusion, bendamustine was efficacious and well tolerated in Taiwanese patients with indolent NHL and MCL with a similar PK profile to that of other populations.