Phase I Study of the Combination of Bendamustine, Rituximab, and Pixantrone in Patients With Relapsed/Refractory B-cell Non-Hodgkin Lymphoma

Abstract

BackgroundFor patients with aggressive lymphomas who relapse after initial therapy, a durable response is rarely achieved with standard salvage therapies. Significant efforts have focused on the development of novel treatments with reduced toxicity. We conducted a phase I prospective single arm clinical trial of the novel combination of BuRP (bendamustine, rituximab, and pixantrone) in patients with relapsed/refractory (R/R) aggressive B-cell non-Hodgkin lymphoma (NHL). Patients and MethodsEligible patients included adults with biopsy-proven R/R B-cell NHL who met the criteria for treatment. Patients received bendamustine 120 mg/m2, rituximab 375 mg/m2, and pixantrone, per cohort dose, on day 1 for up to 6 cycles. Dose escalation used a 3 + 3 design, from a starting dose level of pixantrone 55 mg/m2 to 115 mg/m at dose level 3. ResultsTwenty-two patients were enrolled onto the study with a median follow-up of 7.9 months. The maximum tolerated dose was not reached, but the highest dose level of pixantrone of 115 mg/m2 was well-tolerated. The most common grade 3/4 adverse events were neutropenia (27%) and thrombocytopenia (23%). The mean change in left ventricular ejection fraction was 2.5% (standard deviation, 5.51%; 95% confidence interval, 0.0%-4.9%). The overall response rate for the entire cohort was 37.5% (95% confidence interval, 15%-65%), but at the highest pixantrone dose, the overall response rate was 63%, with a complete response rate of 25%. ConclusionThe BuRP regimen was found to be safe in patients with R/R B-cell NHL. The favorable toxicity profile plus the encouraging response rates seen suggest that continued investigation of the highest dose level is warranted.