Study of Selinexor and Venetoclax in Combination With Chemotherapy in Pediatric and Young Adult Patients With Refractory or Relapsed Acute Myeloid Leukemia

The purpose of this study is to test the safety and determine the best dose of venetoclax and selinexor when given with chemotherapy drugs in treating pediatric and young adult patients with acute myeloid leukemia (AML) or acute leukemia of ambiguous lineage (ALAL) that has come back (relapsed) or did not respond to treatment (refractory). Primary Objective * To determine the safety and tolerability of selinexor and venetoclax in combination with chemotherapy in pediatric patients with relapsed or refractory AML or ALAL. Secondary Objectives * Describe the rates of complete remission (CR) and complete remission with incomplete count recovery (CRi) for patients treated with selinexor and venetoclax in combination with chemotherapy at the recommended phase 2 dose (RP2D). * Describe the overall survival of patients treated at the RP2D. Exploratory Objectives * Explore associations between leukemia cell genomics, BCL2 family member protein quantification, BH3 profiling, and response to therapy as assessed by minimal residual disease (MRD) and variant clearance using cell-free deoxyribonucleic acid (DNA) (cfDNA). * Describe the quality of life of pediatric patients undergoing treatment with selinexor and venetoclax in combination with chemotherapy and explore associations of clinical factors with patient-reported quality of life outcomes. * Describe the clinical and genetic features associated with exceptional response to the combination of venetoclax and selinexor without the addition of chemotherapy.