Inclusion Criteria:

Patients must fulfill all of the following criteria to be eligible for study participation
and have:

- Histologically confirmed PTCL not otherwise specified, angioimmunoblastic T-cell
lymphoma, extranodal natural killer (NK)/T-cell lymphoma nasal type, enteropathy-
type T-cell lymphoma, subcutaneous panniculitis-like T-cell lymphoma, cutaneous γδ
T-cell lymphoma (excludes mycosis fungoides or Sezary syndrome), transformed mycosis
fungoides, hepatosplenic T-cell lymphoma, anaplastic large cell lymphoma (ALCL;
anaplastic lymphoma kinase [ALK]-1 negative), or patients with ALK 1 expressing ALCL
(ALK-1 positive) who have relapsed disease after autologous stem cell transplant
(ASCT);

- Age ≥18 years;

- Written informed consent;

- Progressive disease following at least one systemic therapy or refractory to at least
one prior systemic therapy;

- Measurable disease according to the International Workshop Response (IWC) criteria
and/or measurable cutaneous disease;

- Eastern Cooperative Oncology Group (ECOG) performance status of 0-2;

- Serum potassium ≥3.8 mmol/L and magnesium ≥0.85 mmol/L (electrolyte abnormalities can
be corrected with supplementation to meet inclusion criteria);

- Negative urine or serum pregnancy test on females of childbearing potential; and

- All women of childbearing potential must use an effective barrier method of
contraception (either an intrauterine contraceptive device [IUCD] or double barrier
method using condoms or a diaphragm plus spermicide) during the treatment period and
for at least 1 month thereafter. Male patients should use a barrier method of
contraception during the treatment period and for at least 1 month thereafter.
Hormonal methods of contraception such as the contraceptive pill or patch
(particularly those containing ethinyl-estradiol) should be avoided due to a
potential drug interaction.

Exclusion Criteria:

Patients are ineligible for entry if any of the following criteria are met:

- Known central nervous system (CNS) lymphoma [computed tomography (CT) or magnetic
resonance imaging (MRI) scans are required only if brain metastasis is suspected
clinically];

- Chemotherapy or immunotherapy within 4 weeks of study entry (6 weeks if nitrosoureas
given);

- Initiation of corticosteroids during study (defined as 7 days prior to Cycle 1 Day
1[C1D1] until study drug discontinuation)

- Patients treated with a pulse of steroids were to discontinue steroid use 7 days
prior to C1D1 and have a repeat CT scan and disease assessment after
discontinuation of corticosteroids and before starting romidepsin;

- Concomitant use of any other anti-cancer therapy;

- Concomitant use of any investigational agent;

- Use of any investigational agent within 4 weeks of study entry;

- Any known cardiac abnormalities such as:

- Congenital long QT syndrome;

- QTc interval >480 milliseconds (msec);

- A myocardial infarction within 6 months of C1D1. Patients with a history of
myocardial infraction between 6 and 12 months prior to C1D1 who are asymptomatic
and have had a negative cardiac risk assessment (treadmill stress test, nuclear
medicine stress test, or stress echocardiogram) since the event may participate;

- Other significant electrocardiogram (ECG) abnormalities including 2nd degree
atrio-ventricular (AV) block type II, 3rd degree AV block, or bradycardia
(ventricular rate less than 50 beats/min).

- Symptomatic coronary artery disease (CAD), e.g., angina Canadian Class II-IV.
In any patient in whom there is doubt, the patient should be referred to a
cardiologist for evaluation;

- An ECG recorded at screening showing significant ST depression (ST depression of
≥2 mm, measured from isoelectric line to the ST segment at a point 60 msec at
the end of the QRS complex). If in any doubt, the patient should have a stress
imaging study and, if abnormal, angiography to define whether or not CAD is
present;

- Congestive heart failure (CHF) that meets New York Heart Association (NYHA)
Class II to IV definitions and/or ejection fraction <40% by MUGA scan or <50% by
echocardiogram and/or MRI;

- A known history of sustained ventricular tachycardia (VT), ventricular
fibrillation (VF), Torsade de Pointes, or cardiac arrest unless currently
addressed with an automatic implantable cardioverter defibrillator (AICD);

- Hypertrophic cardiomyopathy or restrictive cardiomyopathy from prior treatment
or other causes (if in doubt, see ejection fraction criteria above);

- Uncontrolled hypertension, i.e., blood pressure (BP) of ≥160/95; patients who
have a history of hypertension controlled by medication must be on a stable dose
(for at least one month) and meet all other inclusion criteria;

- Any cardiac arrhythmia requiring anti-arrhythmic medication;

- Serum potassium <3.8 mmol/L or serum magnesium <0.85 mmol/L (electrolyte
abnormalities can be corrected with supplementation to meet inclusion criteria);

- Concomitant use of drugs that may cause a significant prolongation of the QTc;

- Concomitant use of CYP3A4 significant or moderate inhibitors;

- Concomitant use of therapeutic warfarin or another anticoagulant due to a potential
drug interaction. Use of a small dose of a anticoagulant to maintain patency of
venous access port and cannulas is permitted;

- Clinically significant active infection;

- Known infection with human immunodeficiency virus (HIV), hepatitis B, or hepatitis C;

- Previous extensive radiotherapy involving ≥30% of bone marrow (e.g., whole pelvis,
half spine), excluding patients who have had total body irradiation as part of a
conditioning regimen for ASCT;

- Major surgery within 2 weeks of study entry;

- Previous allogeneic stem cell transplant;

- Inadequate bone marrow or other organ function as evidenced by:

- Hemoglobin <9 g/dL (transfusions and/or erythropoietin are permitted);

- Absolute neutrophil count (ANC) ≤1.0 × 10^9 cells/L [patients with neutropenia
(ANC 1-1.5 10^9 cells/L) as a function of their disease may be supported with
granulocyte-colony stimulating factor (G-CSF)];

- Platelet count <100 × 10^9 cells/L or platelet count <75 × 10^9 cells/L if bone
marrow disease involvement is documented;

- Total bilirubin >2.0 × upper limit of normal (ULN) or >3.0 × ULN in the presence
of demonstrable liver metastases;

- Aspartate transaminase/serum glutamic oxaloacetic transaminase (AST/SGOT) and
alanine transaminase/serum glutamic pyruvic transaminase (ALT/SGPT) >2.0 × ULN
or >3.0 × ULN in the presence of demonstrable liver metastases; or

- Serum creatinine >2.0 × ULN;

- Patients who are pregnant or breast-feeding;

- Coexistent second malignancy or history of prior solid organ malignancy within
previous 3 years (excluding basal or squamous cell carcinoma of the skin, and in situ
carcinoma of the cervix (CIN 1) that has been treated curatively);

- Any prior history of a hematologic malignancy (other than T-cell lymphoma);

- Any significant medical or psychiatric condition that might prevent the patient from
complying with all study procedures; or

- Prior exposure to romidepsin (other histone deacetylase inhibitors are allowed).