Study Description:

The purpose of this study is to find out what effects, good and/or bad, study treatment with talazoparib in combination with conventional chemotherapy agents topotecan and gemcitabine has on you and your cancer.

In this study, we are looking at the use of talazoparib in combination with topotecan and gemcitabine for children and young adults with relapsed (reappeared)/refractory (not responding to treatment) acute myeloid leukemia (AML) or acute leukemia of ambiguous (uncertain) lineage.

Talazoparib will initially be given on days 1-5 concurrently with topotecan and a single dose of gemcitabine on day 1 of each 28-day cycle for 1 or 2 cycles (expansion phase and in the dose escalation phase for subjects who respond to treatment). Subjects on dose level 5 will receive an additional 5-day course of talazoparib alone on days 15-19.

Study Eligibility:

Inclusion Criteria:

1. Patient is young adult or child aged ≤ 21 years.

2. Patient has been diagnosed with refractory or relapsed leukemia [either acute myeloid leukemia (AML) or acute leukemia of ambiguous lineage], without evidence of acute graft versus host disease (GVHD).

3. Greater than 60 days has passed since patient received prior hematopoietic stem cell transplant.

4. A minimum of 14 days has passed since completion of myelosuppressive therapy or gemtuzumab ozogamicin and the first dose of talazoparib.

5. A minimum of 24 hours has elapsed since the patient has completed any low-dose or non-myelosuppressive therapy

Exclusion Criteria

1. Patients with down syndrome.

2. Patients with Acute Promyelocytic leukemia (APL) or Juvenile Myelomonocytic Leukemia (JMML).

3. Patients with Bone Marrow Failure Syndrome.

4. Pregnant patients or breastfeeding patients unwilling to abstain from breastfeeding.

5. Patients with uncontrolled systemic fungal, bacterial, viral or other infection.

Contact Information: For more information can contact Gabbey Hobbs at 501-364-5053 or