Inclusion Criteria:

- ≥ 18 years old

- Refractory or relapsed indolent NHL. Eligible WHO histologies include follicular NHL
(Grades 1, 2, and 3); marginal zone nodal; marginal zone splenic; and
mucosa-associated lymphoid tissue (MALT) types

- Failed ≥ 1 previous regimens, one of which must have contained rituximab as either a
single agent or in combination with chemotherapy

- ECOG performance status score either 0 or 1

- Willing and able to provide written informed consent

Exclusion Criteria:

Laboratory values of:

- Platelet count < 50,000/µL

- AST or ALT > 2 x the upper limit of normal (ULN)

- Total bilirubin > 2 x ULN

- Creatinine > 2.0 mg/dL

and

- Greater than three prior regimens (where a regimen is defined as a treatment for NHL
given after disease progression)

- Uncontrolled hypertension

- Known history of porphyria, G6PD deficiency, HIV