Inclusion Criteria:

- Patients must have histologically confirmed BCR-ABL1 associated (Ph+) acute
lymphoblastic leukemia (ALL) with primary refractory or relapsed disease;
demonstration of BCR-ABL1 in leukemia cells by one or more of the following is
required: t(9;22)(q34;q11.2) cytogenetics; FISH for BCR-ABL1 fusion; RT-PCR for
BCR-ABL1 fusion

- Prior treatment with tyrosine kinase inhibitors (including imatinib, nilotinib and/or
dasatinib) is allowed, although patients must be off any tyrosine kinase inhibitor
for a minimum of 72 hours prior to beginning protocol therapy

- ECOG performance status of 0, 1 or 2

- Total WBC =< 150,000 with no evidence for ongoing or impending leukostasis

- Total bilirubin =< 2.0 mg/dL unless elevated due to Gilbert's, hemolysis or leukemic
infiltration

- Aspartate transaminase (AST)/alanine transaminase (ALT) =< 2.5 × upper limit of
normal (ULN) unless due to leukemic infiltration

- Serum creatinine =< 2.0 mg/dL or creatinine clearance > 50 ml/min

- Left ventricular ejection fraction (LVEF) >= 45% as measured by echocardiogram (ECHO)
or MUGA

- Patients who have undergone stem cell transplantation (SCT), autologous or
allogeneic, are eligible provided that they are > 4 weeks from stem cell infusion,
have no active GVHD, and meet other eligibility criteria

- Patients who fail primary induction therapy or relapse after achieving complete
remission (CR) are eligible if they are > 3 weeks off cytotoxic chemotherapy and > 2
weeks off radiation therapy; patients must be off biologic therapies including
hematopoietic growth factors > 1 week; if using hydroxyurea (HU), steroids, or other
non-cytotoxics for blast count control, patient must be off for > 24 hrs before
starting protocol therapy; patients must have recovered from all acute toxicities
from any previous therapy

- Female patients of childbearing age must have negative pregnancy test; women of
child-bearing potential and men must agree to use adequate contraception (hormonal or
barrier method of birth control; abstinence) prior to study entry and for the
duration of study participation; should a woman become pregnant or suspect she is
pregnant while participating in this study, she should inform her treating physician
immediately

- Ability to understand and the willingness to sign a written informed consent document

Exclusion Criteria:

- Patients may not be receiving any other investigational agents

- Active CNS leukemia; patients with known previous CNS leukemia may continue to
receive intrathecal therapy with ara-C, methotrexate, and/or thiotepa plus steroids
as prophylaxis against reactivation of previous CNS disease

- Patients may not have received previous treatment with entinostat or other HDAC
inhibitors

- History of allergic reactions attributed to compounds of similar chemical or biologic
composition to entinostat or other agents used in study

- Uncontrolled intercurrent illness including, but not limited to, ongoing or active
untreated infection, symptomatic congestive heart failure, unstable angina pectoris,
unstable cardiac arrhythmia, or psychiatric illness/social situations that would
limit compliance with study requirements

- Pregnant women are excluded from this study; breastfeeding should be discontinued if
the mother is treated with entinostat

- HIV-positive patients on combination antiretroviral therapy are ineligible