Inclusion Criteria:

- Subjects who have been previously diagnosed with CD22-positive, indolent NHL (defined
as follicular, marginal zone, or small lymphocytic lymphoma) that has progressed
after 2 or more prior systemic therapies.

- Previous anticancer treatment given must have contained rituximab and chemotherapy,
or anti CD20 Radio Immuno Therapy. Subjects must have exhibited no response or have
progressed within 6 months from the completion of the most recent rituximab or
rituximab containing therapy or within 12 months of the completion of Radio Immuno
Therapy.

- Measurable disease with adequate bone marrow function, renal and hepatic function

Exclusion Criteria:

- History of, or suggestive of, veno-occlusive disease (VOD) or sinusoidal obstruction
syndrome (SOS) or history of chronic liver disease (eg, cirrhosis) or suspected
alcohol abuse.

- Prior allogeneic hematopoietic stem cell transplant (HSCT).

- Clinical evidence of transformation to a more aggressive subtype of lymphoma or grade
3b follicular lymphoma.