Comparison of Pixantrone + Rituximab With Gemcitabine + Rituximab in Patients With Aggressive B-cell Non-Hodgkin Lymphoma or Follicular Grade 3 Lymphoma Who Have Relapsed After Therapy and Are Not Eligible for Stem Cell Transplant

Eligible patients will be randomized to treatment with pixantrone plus rituximab or
gemcitabine plus rituximab in up to six 28-day cycles. At the time patients experience
progressive disease during study treatment, early follow- up, or intermediate follow-up, they
enter the survival follow up period. Patients who complete study treatment or discontinue
study treatment for any other reason will participate in the follow-up periods.

Early Follow-Up: After treatment completion or discontinuation, patient will enter a 24-week
follow-up period.

Intermediate Follow-Up: After completing the 24-week early follow-up period, patient will
enter an additional 72-week follow-up period.

Survival Follow-Up: All patients will be monitored for survival.

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. Patients with DLBCL transformed from indolent lymphoma must have had a complete or
partial response to a therapy for NHL lasting at least 12 weeks.

Exclusion Criteria:

1. Primary refractory de novo DLBCL or primary refractory follicular grade 3 lymphoma,
defined as documented progression within 12 weeks of the last cycle of the first-line
multi-agent regimen.

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.