This study involves taking a study drug called venetoclax with or without standard of care chemotherapy. The overall goal of this study is to see if adding venetoclax to standard chemotherapy leads to improved survival for children and young adults with relapsed acute myeloid leukemia (AML). The study may last up to 9 years and will enroll male and female patients from the ages of 29 days to 21 years of age.

The purpose of this study is to see if a new investigational topical (applied to the skin) formulation of sirolimus, PTX-022 (the study drug), is safe and effective in treating participants with microcystic Lymphatic Malformations.