Inclusion Criteria

Diagnosis and disease status:

- Subjects with CD20+, B-cell, Non-Hodgkin's lymphoma of low-grade or follicular
histology with measurable relapsed or unresponsive disease after prior therapy;
mantle cell and chronic lymphocytic leukemia subtypes are excluded.

- Subjects who previously received a single-agent course of rituximab and showed no
tumor response, or had a response lasting < 6 months. The previously administered
rituximab must have included at least 75% of the standard 4-week regimen (4 x 375
mg/m2). A record of the previous rituximab treatment and response must be available
as a source document at the site.

Exclusion:

- Subjects who showed no tumor response or a response lasting <6 months to treatment
with Rituximab in combination with Chemotherapy or another therapeutic modality
(radiation or radioimmunoconjugates).

- HIV positive.

- Symptomatic thyroid disease requiring medical intervention other than replacement
treatment for hypothyroidism.

- Clinically significant cardiac, pulmonary, and /or hepatic dysfunction (if subject
has history of congestive heart failure or myocardial infarction, must have been
stable for at least 6 months, and have no current symptoms

- If cardiac ejection fraction has been measured, it must be greater than 50%.