This multi-center, open-label, Phase 1b study will evaluate the safety, pharmacokinetics and efficacy of RO5045337 in combination with cytarabine in patients with acute myelogenous leukemia. In Arm A, cohorts of previously untreated patients deemed unsuitable for standard induction therapy will receive escalating oral doses of RO5045377 and cytarabine 20 mg/m2 subcutaneously daily for Days 1 to 10 of each 28-day cycle. In Arm B, cohorts of patients who have relapsed or are refractory after at least one cytarabine/anthracycline containing regimen will receive escalating oral doses of RO5045377 on Days 1 to 5 and cytarabine 1 gm/m2 intravenously on Days 1 to 6 of each 28-day cycle. Patients will receive up to 4 cycles of therapy, patients in Arm A who achieve hematologic response may continue additional cycles until disease progression.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• Patients with histologically or cytologically documented acute myelogenous leukemia appropriate for cytarabine therapy including:
• Arm A: Patients who have not received prior standard induction chemotherapy, considered unsuitable for standard induction therapy
• Arm B: Patients who have failed their 1st or greater line of standard induction chemotherapy (primary refractory) or patients who originally achieved a complete response but are currently in first or greater relapse
• Eastern Cooperative Oncology Group (ECOG) performance status 0 to 2
• All non-hematological adverse events of any prior chemotherapy, surgery, or radiotherapy must have resolved to NCI-CTC AE Grade \