Inclusion Criteria:

• Pathologic confirmation of relapsed or refractory classical Hodgkin's lymphoma.
• The patient has at least one site of measurable disease (≥ 2.0 cm) as measured by conventional techniques such as CT or MRI.
• Prior treatment: there is no limit to number of prior therapies. Patients who had prior allogeneic stem cell transplants and do not have evidence of graft versus host disease and are not receiving immunosuppressive agents are eligible if they meet all other inclusion criteria.
• ECOG performance status of 0 or 1.
• Aged 18 years or older (no safety data yet for ages < 18).
• Laboratory requirements (must be done within 7 days prior to study initiation).

Exclusion Criteria:

• Patients with another active cancer (excluding basal cell carcinoma or cervical intraepithelial neoplasia [CIN/cervical in situ] or melanoma in situ). Prior history of cancer is allowed, as long as there is no active disease.
• Pregnant or lactating women. Women of child-bearing potential (WOCBP) must have a negative serum pregnancy test documented within 7 days prior to start of study drug.
• WOCBP and men whose partners are WOCBP must use an acceptable method of contraception while enrolled in this study, and for a period of 3 months following study drug treatment.
• Patients with uncontrolled intercurrent illness, active or uncontrolled infections, or a fever > 38.5°C (not due to tumor fever) on the day of scheduled dosing.