Main

Inclusion Criteria:

- Subjects with CD20-positive, B cell NHL who, after at least 2 prior therapies of
probable clinical benefit, have relapsed or refractory disease. The following
histologies may be included*: lymphoplasmacytic lymphoma (formerly known as
lymphoplasmacytoid lymphoma), splenic marginal zone B cell lymphoma, extranodal
marginal zone B cell lymphoma of mucosa-associated lymphoid tissue, nodal marginal
zone B cell lymphoma, follicular lymphoma, mantle cell lymphoma, diffuse large-cell B
cell lymphoma, and mediastinal large B cell lymphoma. Small lymphocytic lymphoma
will be included if it is a primary diagnosis and if the lymphoma cells are < 5.0 x
109/L (5000/mm3) in the peripheral blood. *Subjects enrolled in the preliminary
efficacy cohorts must have relapsed, refractory, or persistent follicular lymphoma
(persistent disease defined as computed tomography (CT) positive for 3 months after
last treatment), and must not have received anti-CD20 targeted therapy within 3
months of receiving the first dose of test article. Subjects may be considered
eligible after a single therapy of probable clinical benefit, if no further standard
effective treatment is available in the opinion of the investigator. Prior CD20
immunophenotyping of tumors to document B cell NHL is acceptable. If such prior
documentation is not available, then the immunophenotype of the current disease must
be documented by fine-needle aspirate or biopsy, or by circulating CD20-positive NHL
cells from peripheral blood before administration of test article.

- At least 1 measurable lesion that is 1.5 cm in at least 1 dimension by CT or magnetic
resonance imaging (MRI), in an area of no prior radiation therapy, or documented
progression in an area that was previously irradiated.

- Recovery to baseline or grade 1 [according to the National Cancer Institute (NCI)
Common Terminology Criteria for Adverse Events (CTCAE), version 3.0] from all acute
adverse effects of prior therapies (excluding alopecia).

Main Exclusion Criteria:

- Candidate for potentially curative therapy that is available to the subject, in the
clinical opinion of the investigator.

- Diagnosis of chronic lymphocytic leukemia, Burkitt's lymphoma, primary effusion
lymphoma, and/or precursor B cell lymphoblastic lymphoma.

- Prior treatments: radioimmunotherapy; allogeneic hematopoietic stem cell transplant
(within 6 months of first dose of study drug); chemotherapy, cancer immunosuppressive
therapy, growth factors (except erythropoietin), or investigational agents (within 4
weeks of first dose of study drug); major surgery not related to debulking surgical
procedures (within 3 weeks of first dose of study drug).