The study will determine the maximal tolerated dose (MTD) of panobinostat administered in combination with a fixed combination of cytarabine (ara-C) and mitoxantrone in adult patients with relapsed or refractory acute myeloid leukemia (AML).

Inclusion Criteria:

• Patients with cytopathologically confirmed diagnosis of AML according to WHO criteria, excluding acute promyelocytic leukemia.
• First relapsed AML
• Primary refractory AML defined as failure to respond to initial induction chemotherapy (no CR) or recurrence within 6 months of initial CR.
• Age more than 18 years
• ECOG performance status < 2

Exclusion Criteria:

• Prior treatment with deacetylase inhibitor
• Concurrent therapy with any other investigational agent
• Patients who have received cumulative doses (or its equivalent to other anthracyclines) of more than 360 mg/m2 of doxorubicin will be excluded from the study.
• Clinical symptoms suggesting CNS leukemia
• LVEF below 45% Other protocol-defined inclusion/exclusion criteria may apply