A Study of the Safety and Pharmacokinetics of Venetoclax in Pediatric and Young Adult Patients With Relapsed or Refractory Malignancies

Inclusion Criteria:

- Participants must have relapsed or refractory cancer.

- Participants must have adequate hepatic and kidney function.

- Participants less than or equal to 16 years of age must have performance status of
Lansky greater than or equal to 50% and participants greater than 16 years of age must
have performance status of Karnofsky greater than 50%.

- Participants with solid tumors (with the exception of neuroblastoma) must have
adequate bone marrow function in Part 1.

- For the fifth cohort during Part 2 Cohort Expansion, participants with solid tumors
must have evidence of BCL-2 expression.

Exclusion Criteria:

- Participants with primary brain tumors or disease metastatic to the brain.

- For participants with leukemia, has overt central nervous system (CNS) disease (CNS 3
status).

- Participants who have received any of the following within the listed time frame,
prior to the first dose of study drug

- Biologic agent (i.e., antibodies) for anti-neoplastic intent within 30 days

- CAR-T infusion or other cellular therapy within 30 days

- Anticancer therapy including blinatumomab or chemotherapy, radiation therapy,
targeted small molecule agents, investigational agents within 14 days or 5
half-lives, whichever is shorter

- Steroid therapy for anti-neoplastic intent within 5 days

- Requires ongoing hydroxyurea (hydroxyurea permitted up to first dose)

- Participants who are less than 100 days post-transplant, or greater than or equal to
100 days post-transplant with active graft versus host disease (GVHD), or are
receiving immunosuppressant therapy within 7 days prior to first dose of study drug.

- Participants who are less than 6 weeks post-131 I-metaiodobenzylguanidine (mIBG)
therapy.

- Participants who have received the following within 7 days prior to the first dose of
study drug:

- Strong and moderate Cytochrome P450 3A (CYP3A) inhibitors (Part 1 Dose
Determination);

- Strong and moderate CYP3A inducers (Part 1 Dose Determination and Part 2 Cohort
Expansion).

- Participants who have not recovered from clinically significant adverse
effect(s)/toxicity(s) of the previous therapy.

- Participants who have active, uncontrolled infections.

- Participants with malabsorption syndrome or any other condition that precludes enteral
administration.