Pharmacokinetic Study of Venetoclax Tablets Crushed and Dissolved Into a Solution

Inclusion Criteria: * Age: Patients must be \<39 years of age at time of study enrollment * Diagnosis: Patients may have a diagnosis of any hematologic malignancy * Central access: Patients must have an existing venous or arterial access line for PK blood draws * Weight requirement: Patients must weigh at least 5.5 kg at the time of enrollment * Venetoclax: Patients must be receiving any dose of venetoclax given as a solution made from crushed tablets by mouth (PO) or via nasogastric (NG), or G-tube as prescribed by their treating oncologist. * Concurrent chemotherapy medications: Patients may receive venetoclax as a single agent or in combination with any other chemotherapeutic agents. Exclusion Criteria: * Pregnant women are excluded from this study because venetoclax has the potential for teratogenic or abortifacient effects. Because there is an unknown but potential risk for adverse events in nursing infants secondary to treatment of the mother with venetoclax, breastfeeding should be discontinued if the mother is treated with venetoclax. * Males or females of reproductive potential may not participate unless they have agreed to use an effective contraceptive method while on study treatment and for six months following completion.