Phase I/II Study of Bendamustine in Combination With Ofatumumab, Carboplatin and Etoposide

Fifty percent of patients with aggressive B cell non-Hodgkin lymphomas are expected to relapse after initial standard chemotherapy. There is no standard salvage regimen for patients with relapsed or refractory disease and at least 75% of patients are expected to succumb to their condition with the commonly used therapy. The recent CORAL study was evaluating the most frequently used rescue regimens R-ICE (rituximab, ifosfamide, carboplatin, etoposide) vs. R-DHAP (rituximab, dexamethasone, high-dose cytarabine and cisplatin) for relapsed aggressive lymphomas, the overall response (OR) was 83% and 3 year event-free survival (EFS) was 47% for "rituximab naïve" patients. In contrast, OR was 51% and 3 year EFS was only 21% in patients who had relapsed after a rituximab containing regimen. There was no significant difference between R-ICE and R-DHAP (in 3-year EFS or overall survival). This study confirmed that rituximab containing rescue was less effective in those patients who had received prior rituximab. Currently, there is virtually no relapsed B-cell lymphoma patients who had not received a rituximab containing induction; therefore, novel strategies are needed to overcome rituximab resistance and to improve overall poor outcome in the relapsed setting. Ofatumumab is a human IgG1 monoclonal anti-CD20 antibody which binds to different CD20 epitopes and is presumed to destroy B cells that are insensitive to rituximab due to their low CD20-expression due to its higher binding avidity and higher antibody and complement dependent cytotoxicity. It was approved by FDA for the treatment of patients with refractory Chronic Lymphocytic Leukemia (CLL). It is being actively studied in low grade and aggressive CD20 positive lymphomas. Bendamustine is an alkylator/purine analogue hybrid cytotoxic compound that has demonstrated single agent activity in lymphomas refractory to other alkylating agents, such as cyclophosphamide. Weidmann et al (2002) demonstrated single agent activity and safety of bendamustine at the dose of 120mg/m2 (day 1, 2) in relapse/refractory aggressive lymphomas. This study had an ORR of 44% in 18 patients. Non-hematological toxicity was mild (13% grade 3 and 0 grade 4). Bendamustine has shown impressive activity and a favorable safety profile when used in combination with rituximab and other cytotoxic drugs: Weide R et al (2007) studied bendamustine (90 mg/m2 day 1, 2) in combination with rituximab and mitoxantrone in 57 patients' with indolent lymphomas and mantle cell lymphoma (MCL). ORR was 92% in follicular and 78% in MCL Vacirca et al presented interim safety analysis of bendamustine (120mg/m2, day 1, 2) and rituximab combination in aggressive B cell lymphomas at 2010 ASCO meeting (in 76 cycles 1 grade 4 neutropenia and 9 additional grade 3 events). Thus, bendamustine combinations are effective and can be given safely in patients with relapsed lymphomas. The investigators propose a novel R-ICE-like salvage combination regimen in which rituximab is substituted with ofatumumab and ifosfamide with bendamustine in combination with carboplatin and etoposide for refractory or relapsed aggressive B cell lymphomas. The investigators hope to avoid the substantial ifosfamide mediated urinary bladder toxicity (incidence of grade 3 and 4 hemorrhagic cystitis 8-12%) and neurologic toxicity (10-30%: somnolence, confusion, psychosis and seizure) by substituting ifosfamide for bendamustine. The proposed regimen is convenient and can be administered on the outpatient basis which presents an additional benefit to the patients and to the providers. The investigators propose a phase I/II clinical trial and will first determine safety and toxicity of escalating dose bendamustine in combination with fixed doses of ofatumumab, carboplatin and etoposide. The investigators recognize that the commonly used doses of bendamustine in lymphoid malignancies range from 70-120 mg/m2. The investigators will determine maximum-tolerated dose (MTD) and dose-limiting toxicity (DLT) of the combination by using dose escalation of bendamustine from 70mg/m2 in a standard 3 by 3 design. The investigators will then assess efficacy of the combination regimen in relapsed and refractory aggressive B-cell lymphomas.