Inclusion Criteria:

1. ≥ 18 years old
2. Eastern Cooperative Oncology Group (ECOG) performance status of ≤ 2
3. A history of classical HL (i.e. Nodular sclerosing, Mixed-cellularity, Lymphocyte-rich, Lymphocyte depleted)
4. Has progressive disease after receiving high dose chemotherapy with AHSCT
5. Has progressive disease on or after therapy with a gemcitabine- or vinorelbine- or vinblastine-containing regimen, after first relapse.

6. Laboratory values must be in range, more specifically:

   • Absolute neutrophil count (ANC) ≥ 1.5 x 10 9/L [SI units 1.5 x 109/L]
   • Platelet count ≥ 75 x 109/L
7. A healthy thyroid

Exclusion Criteria:

1. History of prior treatment with a DAC inhibitor
2. Treated with > 5 prior systemic lines of treatment
3. Treated with allogeneic hematopoietic stem cell transplant who has received immunosuppressive therapy within 90 days prior to start of screening and/or have ≥ Grade 2 graft versus host disease (GvHD)
4. History of another primary malignancy ≤ 3 years before study entry, with the exception of non-melanoma skin cancer, and carcinoma in situ of uterine cervix
5. History of CNS involvement with lymphoma
6. Impaired cardiac function or other clinically significant heart disease (e.g., uncontrolled hypertension)
7. Impairment of gastrointestinal (GI) function or GI disease that may significantly alter the absorption of study drug
8. Ongoing diarrhea ≥ grade 2
9. Patient has any other concurrent severe and/or uncontrolled medical condition(s) that could cause unacceptable safety risks or compromise compliance with the protocol
10. History of HIV
11. Has active bleeding diathesis or is currently being treated with therapeutic doses of sodium warfarin (Coumadin®) or other vitamin K active agents
12. Using medications that have a relative risk of prolonging the QT interval or of inducing Torsade de Pointes, where such treatment cannot be discontinued or switched to a different medication prior to starting study drug