Inclusion Criteria:

A patient must meet all of the following criteria in order to be enrolled:

1. Biopsy-confirmed low-grade B-cell lymphoma; specifically, follicular grade 1, 2, or 3A, marginal zone or small lymphocytic lymphoma, of any initial stage. Patients must be relapsed from prior therapy
2. Patients must have one site of disease that is accessible for intratumoral injection of VTX-2337 percutaneously
3. Tumor specimens must be available for immunological studies, either from a previous biopsy or a new biopsy obtained before Day 1 of the study. If applicable, the new biopsy must be obtained from a site of disease other than the intended injection site.
4. Patients must have measurable disease other than the injection site or biopsy site
5. ECOG Performance Status of 1 or better (corresponds to Karnofsky Performance Status (KPS) of >= 70)
6. Patients must be 18 years of age or older.
7. Adequate bone marrow function: WBC >= 2,000/uL; platelet count >= 75,000/mm^3; ANC >= 1000/uL.
8. Adequate renal function: serum creatinine < 2.0mg/dL
9. Adequate hepatic function: bilirubin < 1.5 mg/dL; SGOT/SGPT < 3 x upper limit of normal

10. Required wash out periods for prior therapy:

    • Topical therapy: 2 weeks
    • Chemotherapy: 4 weeks
    • Radiotherapy: 4 weeks
    • Other investigational therapy: 4 weeks
    • Rituximab: 12 weeks
11. Patients of reproductive potential and their partners must agree to use an effective (> 90% reliability) form of contraception during the study and for 4 weeks following the last study drug administration.
12. Women of reproductive potential must have negative urine pregnancy test.
13. Life expectancy greater than 4 months.
14. Able to comply with the treatment schedule.
15. Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

A patient may not be enrolled in the trial if any of the following criteria are met:

1. Pre-existing autoimmune or antibody-mediated disease including: systemic lupus, erythematosus, rheumatoid arthritis, multiple sclerosis, Sjogren's syndrome, autoimmune thrombocytopenia, history of uveitis. Patients with controlled thyroid disease, or the presence of auto-antibodies without clinical autoimmune disease, are permitted on study
2. Known history of human immunodeficiency virus (HIV)
3. Patients with active infection or with a fever > 38.5°C within three days prior to the first scheduled treatment.
4. Known CNS metastases
5. Prior malignancy (active within 5 years of screening) except basal cell or completely excised non-invasive squamous cell carcinoma of the skin, or in situ squamous cell carcinoma of the cervix
6. History of allergic reactions attributed to compounds of similar composition to VTX-2337
7. Current anticoagulant therapy. (ASA <= 325 mg per day is allowed.)
8. Significant cardiovascular disease (i.e. NYHA class 3 congestive heart failure; myocardial infarction with the past 6 months; unstable angina; coronary angioplasty with the past 6 months; uncontrolled atrial or ventricular cardiac arrhythmias).
9. Pregnant or lactating
10. Any other medical history, including laboratory abnormalities, deemed by the Investigator to be likely to interfere with their participation in the study, or to interfere with the interpretation of the results