A Randomized, Open-Label, Multicenter, Phase II Trial Evaluating the Safety and Activity of DCDT2980S in Combination With Rituximab or DCDS4501A in Combination With Rituximab in Patients With Relapsed or Refractory B-cell Non Hodgkin's Lymphoma

Inclusion Criteria:

- Eastern Cooperative Oncology Group (ECOG) Performance Status of 0, 1, or 2

- Life expectancy of at least 12 weeks

- History of histologically documented relapsed or refractory Grades 1-3a follicular
lymphoma, or relapsed or refractory diffuse large B-cell lymphoma

- Availability of an archival or freshly biopsied tumor tissue sample must be confirmed
for study enrollment

- Have a clinical indication for treatment as determined by the investigator

- Must have at least one bi-dimensionally measurable lesion (>1.5 cm in its largest
dimension by CT scan or MRI)

Exclusion Criteria:

- Prior use of any monoclonal antibody, radioimmuno-conjugate or antibody drug
conjugate within 4 weeks before study start

- Treatment with radiotherapy, chemotherapy, immunotherapy, immunosuppressive therapy,
or any investigational anti-cancer agent within 2 weeks prior study start

- Adverse events except for sensory neuropathy from any previous treatments must be
resolved or stabilized to Grade
- Completion of autologous stem cell transplant within 100 days prior study start

- Prior allogeneic stem cell transplant

- Eligibility for autologous SCT (patients with relapsed or refractory DLBCL)

- History of severe allergic or anaphylactic reactions to monoclonal antibody therapy
(or recombinant antibody-related fusion proteins)

- History of other malignancy that could affect compliance with the protocol or
interpretation of results

- Current or past history of CNS lymphoma

- Current Grade > 1 peripheral neuropathy