A phase I/II study of 10-min dosing of bendamustine hydrochloride (rapid infusion formulation) in patients with previously untreated indolent B-cell non-Hodgkin lymphoma, mantle cell lymphoma, or relapsed/refractory diffuse large B-cell lymphoma in Japan

This phase I/II clinical study was conducted to examine the safety, tolerability, pharmacokinetics, and efficacy of 10-min dosing of bendamustine in patients with previously untreated indolent B-cell non-Hodgkin lymphoma (iNHL) or mantle cell lymphoma (MCL) (Group 1) and patients with relapsed/refractory diffuse large B-cell lymphoma (rrDLBCL) (Group 2).Rituximab 375 mg/m2 was administered intravenously every 28 days to Group 1 patients on day 1 and every 21 days to Group 2 patients on day 1. Bendamustine 90 mg/m2/day was administered to the former on days 1 and 2; bendamustine 120 mg/m2/day was administered to the latter on days 2 and 3. Each regimen was delivered up to six cycles for both groups. The primary endpoints were safety and tolerability in Groups 1 and 2, respectively.Among 37 enrolled patients, safety was assessed in 36. In Group 1 (n = 30), 27 patients (90%) had follicular lymphoma. Adverse events (AEs) were observed in all 30 patients in Group 1. Dose-limiting toxicities were observed in two of six patients in Group 2. Common AEs included lymphocyte count decreased (86.7%, 100%). In Group 1, overall response and complete response rates were 93.1% (95% confidence interval [CI] 77.2-99.2%) and 75.9% (95% CI 56.5-89.7%), respectively. The Cmax and AUC of bendamustine tended to be higher in Group 2 than in Group 1.This study showed that bendamustine is safe, well-tolerated and effective for patients with previously untreated iNHL, MCL or rrDLBCL. Pharmacokinetic data were equivalent to those obtained outside of Japan.Registration NCT03900377; registered April 3, 2019.