This is a phase I trial of the combination of bendamustine, rituximab and pixantrone in patients with relapsed/refractory B cell non-Hodgkin lymphoma. A standard 3+3 design will be used to determine the maximum tolerated dose (MTD) of the combination. A static dose of bendamustine and rituximab will be used and the dose of pixantrone will be escalated in each cohort. Pixantrone will be dosed on a 21 day cycle at 55mg/m2, 85mg/m2, and 115mg/m2 in sequential cohorts dependent on acceptable toxicity profile at each dose level. MTD will be determined based on DLTs that occur during the first 2 cycles of the drug combination.

Phase II did not proceed as planned due to withdrawal of pixantrone from the US.

This is a phase I trial utilizing a traditional 3+3 design to evaluate maximum tolerated dose (MTD) and optimal dose schedule of pixantrone in combination with bendamustine (120mg/m2 on day 1 of each 21 day cycle) and rituximab (375mg/m2 on day 1 of each 21 day cycle). No patients will be entered on an escalated dosage level until at least 3 patients have been treated at the previous level and assessed for a dose limiting toxicity. Dose levels will be escalated in cohorts of 3 patients as long as no drug-related DLT occurs in the first 2 cycles. If one patient is observed to suffer a DLT, this cohort will be expanded to include at least 6 patients total. If less than 2 patients in the expanded cohort of 6 patients experience a DLT, dose escalation will resume. If 2 of 6 patients enrolled at the same dose level experience a DLT, the MTD has been exceeded, and the dose escalation will cease. The next lower dose will be considered the MTD. If any patient withdraws from the study prior to completing 2 cycles for reasons other than a DLT then that patient will be replaced in order to determine the MTD.

If dose limiting toxicity is observed at the initial dose level in 2 patients, the MTD has been exceeded and the starting dose level will be reduced to 25mg/m2. If 1 patient experiences a DLT in the -1 dose range, the cohort will be expanded to at least 6 patients. If a second patient experiences a DLT at the -1 dose level, the trial will be closed.

For part 1, those who have a confirmed diagnosis of relapsed/refractory B cell non-Hodgkin's lymphoma of any subtype will be considered eligible for enrollment. Each cycle will be 21 days. Subjects will be assessed for DLTs during the first 2 cycles of study drug. They will be assessed for response after cycle 2. Patients not experiencing a DLT during the first 2 cycles and who have stable disease or better may continue to receive up to 6 cycles of treatment with the triplet combination. If any patient withdraws from the study prior to completing 2 cycles for reasons other than a DLT then that patient will be replaced in order to determine the MTD.

Phase II did not proceed as planned due to withdrawal of pixantrone from the US.

Inclusion Criteria:

1. Part I: Subjects must have relapsed or refractory B cell NHL;

2. Part II: Subjects must have relapsed or refractory aggressive B cell NHL including follicular lymphoma (FL) grade 3, Diffuse Large B Cell Lymphoma (DLBCL), transformed NHL, mantle cell lymphoma (MCL), or other aggressive B cell NHL histology as per the WHO 2008 criteria;

3. Refractory disease (defined as persistence of evaluable disease after therapy) or relapsed disease following at least one prior treatment regimen that should include autologous stem cell transplant unless a patient was not eligible or refused prior transplant;

4. Age ≥ 18 years old;

5. Eastern Cooperative Oncology Group (ECOG) performance status of ≤2;

6. Subjects must have measurable or evaluable disease based on physical exam and/or radiographs (CT, MRI, PET) or bone marrow involvement;

7. Female subject is either post-menopausal or surgically sterilized;

8. Laboratory Values:

   • Absolute neutrophil count (ANC) ≥ 1.5 x 10^9/L; lower levels accepted if due to marrow involvement by lymphoma
   • Platelets ≥ 75,000/mcl; lower levels accepted if due to marrow involvement by lymphoma
   • Total bilirubin ≤ 1.5 X institutional upper limit of normal; ≤ 3.0 ULN accepted in subjects with Gilbert's Syndrome
   • AST/ALT ≤ 1.5 X institutional upper limit of normal. Subjects with known liver involvement by lymphoma: AST/ALT ≤ 2 X institutional upper limit of normal
   • Serum creatinine < 1.5 X institutional upper limit of normal

9. Ability to provide written informed consent obtained prior to participation in the study and any related procedures being performed

Exclusion Criteria:

1. No chemotherapy, radiation, biologics or immunotherapy within 2 weeks prior to registration (6 weeks if last received BCNU or mitomycin C).

2. No radioimmunotherapy within 2 months prior to registration.

3. Subjects receiving chronic, systemic treatment with corticosteroids equivalent to > 20mg of prednisone per day. Subjects receiving replacement for adrenal insufficiency will be allowed on the study. Topical or inhaled corticosteroids are allowed.

4. Subjects with a history of another primary malignancy ≤ 3 years ago, with the exception of inactive basal, squamous cell carcinoma of the skin or superficial melanoma only requiring excision, prostate cancer with a PSA that has not increased for at least 3 months, carcinoma in situ of the cervix.

5. Major surgery ≤ 4 weeks prior to registration. Minor surgery ≤ 2 weeks prior to registration. Insertion of a vascular access device is not considered major or minor surgery. Subjects must have recovered from all surgery related toxicities to ≤ grade 1 or to baseline if subject started with > grade 1 toxicity, not otherwise violating the above inclusion criteria.

6. Subjects who have received investigational drugs ≤ 4 weeks prior to registration.

7. Impaired Cardiac Function:

   • QTc > 480 on screening ECG.
   • Previous history of angina pectoris or acute MI within 6 months
   • Congestive heart failure (New York Heart Association functional classification III-IV) or baseline MUGA/ECHO shows estimated LVEF < 45%
   • Any history of torsade de pointes, ventricular fibrillation, uncontrolled ventricular tachycardia, or uncontrolled atrial fibrillation.

8. Female patients who are pregnant or breastfeeding

9. Patients with history of untreated hepatitis B or who are known carriers of hepatitis B will be excluded from this trial. All subjects will be screened prior to study entry.

10. Concurrent use of other anti-cancer agents or anti-cancer treatments.

Up to 220 days

Subjects who received at least 2 cycles of study drug were included. Data from the single patient enrolled in the phase 2 portion of the trial was included with the phase I pixantrone 115mg/m2 group because the phase 2 patient also received the 115mg/m2 dose and the combined data seems more meaningful than presenting data for 1 patient separately.