A Randomized Multicenter Study Comparing Pixantrone + Rituximab With Gemcitabine + Rituximab in Patients With Aggressive B-cell Non-Hodgkin Lymphoma or Follicular Grade 3 Lymphoma Who Have Relapsed After Therapy With CHOP-R or an Equivalent Regimen and Are Ineligible for Stem Cell Transplant

Inclusion Criteria:

1. Diagnosis of DLBCL (de novo DLBCL, or transformed from indolent lymphoma) or
follicular grade 3 lymphoma on the basis of tissue biopsy.

2. Patients with de novo DLBCL must have received 1-3 treatment regimens for DLBCL.
Patients with follicular grade 3 lymphoma must have received 1-3 treatment regimens
for follicular lymphoma (any grade). Patients with DLBCL transformed from indolent
lymphoma must have received at least 1-4 treatment regimens for NHL.

3. Received rituximab containing a multi-agent therapy for the treatment of NHL.

4. Not eligible for high-dose chemotherapy and stem cell transplant.

5. Response to NHL treatment for patients with DLBCL transformed from indolent lymphoma.

Exclusion Criteria:

1. Primary refractory de novo DLBCL and primary refractory follicular grade 3 lymphoma.

2. Prior treatment with cumulative dose of doxorubicin or equivalent exceeding 450 mg/m2

3. Any experimental therapy ≤ 28 days prior to randomization

4. Other malignancy within last 5 years except for the following: curatively treated
basal cell/squamous cell skin cancer, carcinoma in situ of the cervix, superficial
transitional cell bladder carcinoma, or in situ ductal carcinoma of the breast after
complete resection

5. Any contraindication or known allergy or hypersensitivity to any study drugs

6. Concomitant therapy with any anticancer agents, immunosuppressive agents, other
investigational anticancer therapies. Low-dose corticosteroids for the treatment of
non cancer-related illnesses are permitted.