Summary: As this is an open label study, all patients will receive SDX-105 by 30-60 minute intravenous infusion on day 1 and day 2. Treatment will repeat every 21 days. Treatment can continue for up to one year in the absence of disease progression or unacceptable toxicity. Patients will be followed until disease progression.

Rationale: Drugs used in chemotherapy, such as SDX-105, use different ways to stop tumor cells from dividing so they stop growing or die.

Purpose: This study will evaluate the effectiveness and safety in non-Hodgkin's lymphoma in patients who are refractory to Rituxan.

Inclusion Criteria:

• Documented indolent or transformed B-Cell NHL indolent NHL: follicular B-Cell lymphoma, diffuse small lymphocytic lymphoma, lymphoplasmacytic lymphoma, marginal zone lymphoma
• Documented refractory disease to rituximab therapy, given as a single agent or in combination (defined as no response, or progression within 6 months of completing rituximab treatment.)
• Age of at least 18 years at Screening Visit (Site specific requirement may differ)

Exclusion Criteria:

• Previous chemotherapy or immunotherapy within 3 weeks prior to entering the study (6 weeks for nitrosoureas or mitomycin) or failure to recover from adverse events due to any agents administered previously.
• Use of investigational agents within 28 days of study
• History of prior high dose chemotherapy with allogeneic stem cell support