| Inclusion Criteria: | 1) Patients with diagnosis of CD22-positive, B-cell non-Hodgkin's lymphoma, who progressed after at least two previous treatments. The histologies acceptable are small lymphocytic lymphoma, lymphoplasmacytic lymphoma, splenic marginal zone B-cell lymphoma, nodal marginal cell lymphoma, MALT lymphoma, follicular lymphoma, mantle cell lymphoma, diffuse large B-cell lymphoma, mediastinal large B-cell lymphoma. SLL will be included if the peripheral blood lymphoma cells are less than 5.0 x 10^9/L.
2) Age 18 years or older
3) ECOG performance status </= 2
4) Life expectancy >/= 12 weeks
5) Absolute neutrophil count >/= 1,500/microL, platelets >/= 100,000/microL or >/= 75,000/microL if due to bone marrow disease burden based on the judgement of the investigator.
6) Serum Creatinine, Total Bilirubin </= 1.5 x ULN, AST/SGOT and ALT/SGPT </= 2.5 x ULN
7) At least 1 measurable disease lesion at inclusion in area of no prior radiation therapy, or clear progression in an area previously irradiated. The lesion has to be at least 1.5 cm in one of the diameter by CT or MRI at inclusion.
8) Negative pregnancy test within a week.
9) Signed informed consent.
10) At the MTD part 2 of the study, patients must have one of the followings: a) Follicular lymphoma previously treated with at least one dose of rituximab, but have not received radioimmunotherapy; b) Diffuse large B-cell lymphoma |