Inclusion Criteria:

- Patients must have histologically or cytologically confirmed relapsed/refractory
non-Hodgkin lymphoma (NHL) with any of the following T-cell histologies:

- Peripheral T-cell NHL (PTCL) not otherwise specified (NOS)

- Anaplastic large cell T-cell lymphoma (ALCL) that is anaplastic lymphoma kinase
either positive or negative

- Angioimmunoblastic T-cell NHL

- Subcutaneous panniculitis-like T-cell lymphoma

- Enteropathy-associated T-cell NHL

- Hepatosplenic T-cell lymphomas

- Extranodal NK/T-cell lymphoma, nasal type

- Adult T-cell leukemia/lymphoma

- Unclassifiable PTCL

- Transformed cutaneous T-cell lymphoma (CTCL) to PTCL with systemic involvement
(not local skin transformation)

- No other histologies are eligible; examples of ineligible histologies include:
T-cell prolymphocytic leukemia, T-cell large granular lymphocytic leukemia,
NK-cell leukemia, mycosis fungoides, Sezary syndrome, lymphomatoid papulosis,
and primary CTCL

- Patients must have received at least one course of prior systemic therapy which may
include chemotherapy, antibody therapy, or immunotherapy; for all forms of systemic
therapy, patients must have completed therapy at least 21 days prior to registration;
patients must not be within 84 days of radioimmunotherapy; steroids at a low dose for
control of itching (up to the equivalent of 20 mg of prednisone daily) are allowed

- Adequate sections and a paraffin block from the relapsed/refractory specimen must be
submitted for review by the lymphoma pathology group; an adequate biopsy requires
sufficient tissue to establish the architecture and a Revised European American
Lymphoma (REAL) or World Health Organization (WHO) histologic subtype with certainty;
thus, core biopsies, especially multiple core biopsies MAY be adequate; whereas,
needle aspirations or cytologies are not adequate

- Patients must have bidimensionally measurable disease

- Patients who also have non-measurable disease in addition to measurable disease
must have all non-measurable disease assessed within 42 days prior to
registration

- Patients must have a bilateral or unilateral bone marrow aspirate and biopsy
performed within 42 days prior to registration

- Patients must not have clinical evidence of central nervous system involvement by
lymphoma

- Patients must be able to swallow tablets

- Patients known to be human immunodeficiency virus (HIV)-positive must not have
multi-drug resistant HIV infection, CD4 counts < 150/mcL, or other concurrent
acquired immunodeficiency syndrome (AIDS)-defining conditions

- Absolute granulocyte count >= 1,000 cells/mcL

- Platelet count >= 75,000 cells/mcL (patients with documented marrow involvement may
be transfused to this value)

- Serum bilirubin =< 2 times institutional upper limit of normal

- Patients must have a Zubrod performance status of 0, 1, or 2

- No other prior malignancy is allowed except for the following: adequately treated
basal cell or squamous cell skin cancer, in situ cervical cancer, adequately treated
stage I or II cancer from which the patient is currently in complete remission, or
any other cancer from which the patient has been disease free for five years

- Pregnant or nursing women may not participate

- Women or men of reproductive potential may not participate unless they have agreed to
use an effective contraceptive method

- Patients may have received prior radiation in combination with systemic therapy;
patients must not be within 21 days of external-beam radiation therapy

- Patients must not have received a previous allogeneic stem cell transplant or be
within 90 days of an autologous stem cell transplant