Inclusion Criteria

- Signed informed consent

- Ability and willingness to comply with the requirements of the study protocol

- Age ≥ 18 years

- Documented history of histologically confirmed CD20-positive follicular NHL (Phases I
and II); for Phase I, other CD20-positive indolent lymphomas (marginal zone lymphoma
and small lymphocytic lymphoma) are also included. Patients with a history of a
CD20-positive NHL of mixed (indolent/aggressive) histology may also be included in
Phase I if the most recent relapse biopsy shows only indolent NHL

- Indolent lymphoma (Phase I) or follicular lymphoma (Phase II) that either has
relapsed after a documented history of response (CR, CRu, or PR) of ≥6 months to a
rituximab-containing regimen or was refractory to a previous rituximab-containing
regimen

- Bi-dimensionally measurable disease, with at least one lesion >1.5 cm in its largest
dimension

- Absolute B‑cell count ≥LLN at screening (Phase I only)

- ECOG performance status of 0, 1, or 2

- For patients of reproductive potential (males and females), use of a reliable means
of contraception during the study and for 1 year following the last dose of study
treatment

- For females of childbearing potential, a negative serum pregnancy test within 14 days
prior to enrollment

Exclusion Criteria:

- Prior use of anti-CD20 monoclonal antibody therapy (other than rituximab or
radioimmunotherapy)

- Prior use of any non-CD20-targeted monoclonal antibody therapy within 6 months of
enrollment

- Current or recent lymphoma treatment

- History of severe allergic or anaphylactic reactions to human, humanized, chimeric,
or murine monoclonal antibodies

- Evidence of significant uncontrolled concomitant diseases, such as cardiovascular
disease, nervous system, pulmonary, renal, hepatic, endocrine, or gastrointestinal
disorders

- Evidence of myelodysplasia or myelodysplastic changes on bone marrow examination

- Untreated or persistent/recurrent malignancy (other than lymphoma)

- Known active bacterial, viral, fungal, mycobacterial, or other infection

- A major episode of infection requiring hospitalization or treatment with IV
antimicrobials within 4 weeks of screening or oral antimicrobials within 2 weeks of
screening

- History of recurrent significant infection or bacterial infections

- Positive hepatitis B or C serology

- Positive human immunodeficiency virus (HIV) serology

- Pregnancy or lactation

- Central nervous system lymphoma

- Recent major surgery within 4 weeks of screening, other than diagnostic surgery