A Study of Venetoclax in Combination With Cobimetinib and Venetoclax in Combination With Idasanutlin in Patients Aged >/= 60 Years With Relapsed or Refractory Acute Myeloid Leukemia Who Are Not Eligible for Cytotoxic Therapy

• Histological confirmation of relapsed or refractory AML after prior anti-leukemic therapy by WHO classification
• Ineligible for cytotoxic therapy defined by the following:

a. Age (>/=) 75 years or b. age 18- 74 years with at least one of the following comorbidities: i. Eastern Cooperative Oncology Group (ECOG) Performance Status of 2 or 3 ii. Cardiac history of congestive heart failure requiring treatment or ejection fraction (</=) 50% or chronic stable angina iii. Diffusing capacity of the lungs for carbon monoxide (</=) 65% or forced expiratory volume in the first second of expiration (</=) 65% iv. Creatinine clearance (>/=) 30 mL/min to< 45 mL/min v. any other comorbidity that the physician judges to be incompatible with intensive chemotherapy must be reviewed and approved by the Medical Monitor before screening and study enrollment.

• Life expectancy of at least 12 weeks
• Eastern Cooperative Oncology Group (ECOG) Performance Status 0-2
• Adequate liver and renal function

• Patients with acute promyelocytic leukemia (French-American-British [FAB] class M3 AML)
• Known active central nervous system (CNS) involvement with AML at study entry
• ECOG Performance Status (>/=) 3 in patients who are (>/=) 75 years old or ECOG Performance Status of 4, regardless of age
• Prior exposure to Bcl-2 inhibitors, murine double minute 2 (MDM2) antagonists or prior exposure to experimental treatment targeting Raf, mitogen-activated protein kinase (MEK), or the mitogen-activated protein kinase (MAPK) RAS/RAF/MEK/ERK MAPK pathway
• Positive for hepatitis C virus (HCV), hepatitis B surface antigen (HBsAg) and known history of HIV, malignancy, active infection and cardiovascular diseases (CVs)
• Received strong cytochrome (CYP) 3A inhibitors, moderate CYP3A inhibitors, strong CYP3A inducers and moderate CYP3A inducers within 7 days prior to initiation of study treatment
• History of symptomatic Clostridium difficile infection within 1 month prior to dosing

Additional arm specific exclusion criteria:

Dose Escalation Arm A (Venetoclax and Cobimetinib):

• History or evidence of retinal pathology on ophthalmologic examination that is considered a risk factor for neurosensory retinal detachment/central serous chorioretinopathy (CSCR), retinal vein occlusion (RVO), or neovascular macular degeneration
• Left ventricular ejection fraction (LVEF) below institutional lower limit of normal (LLN) or below 50%, whichever is lower

Arm B (Venetoclax and Idasanutlin):

• Received the following within 7 days prior to the initiation of study treatment: Strong CYP2C8 inhibitors or CYP2C8 substrates, OATP1B1/3 substrates
• Received the following within 14 days prior to the initiation of study treatment: Strong CYP2C8 inducers
• History of liver cirrhosis by radiologic, clinical or laboratory data, or biopsy despite normal liver function tests
• Received treatment with oral or parenteral anticoagulants/anti-platelet agents within 7 days prior to initiation of study treatment.