This study involves taking a study drug called BA3011. The overall goal of this study is to see if BA3011 is a possible treatment for patients with sarcoma.

The purpose of this study is to test the safety and efficacy of the investigational drug called Selpercatinib in children whose cancers have a specific genetic change (RET-fusion or RET-mutation). Selpercatinib has been FDA-approved for adults and pediatric patients 12 years of age or older for certain types of lung and thyroid cancers. Selpercatinib is administered in capsule form, liquid suspension, or may also be administered by a feeding tube for subjects who are unable to swallow.

This study enrolls patients that have been diagnosed with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or mixed phenotype acute leukemia (MPAL) that has either come back (relapsed) or does not respond to therapy (refractory). This study involves taking a drug called uproleselan that is not yet approved for use in children or adults. The purpose of the study is to find a safe dose of the study drug in children that can be given with standard chemotherapy without causing severe side effects.