Inclusion Criteria:

- Adult patients, >/= 18 years of age

- Histologically or cytologically confirmed malignant solid tumors

- Measurable and/or evaluable disease according to RECIST 1.1 criteria

- Eastern Cooperative Oncology Group (ECOG) performance status 0 or 1

- Adequate bone marrow, liver and renal function

Exclusion Criteria:

- Prior chemotherapy, radiotherapy, or hormonal therapy for cancer within 3 weeks of
first study treatment, except for short course palliative radiotherapy for pain

- Antibody therapy or other immunotherapy currently or less than 21 days prior to study
treatment

- Current immunosuppressive therapy, including those prescribed for organ
transplantation and rheumatologic disease

- Corticoid therapy > 10 mg/day prednisone or equivalent

- Patients who have not recovered from > grade 1 (NCI CTCAE) prior adverse events from
any cancer therapy, except for alopecia

- Pregnant or breastfeeding women

- Known hypersensitivity to any component of RO5458640 or previous severe
hypersensitivity reactions to monoclonal antibody therapy

- History of active seizure disorder

- History of CNS or leptomeningeal metastases, except for clinically stable disease for
at least 3 weeks prior to first study drug

- Cardiovascular illness: CVA or MI < 6 months prior to study, CHF > NYHA Class 2, QTcF
>480 msec.

- Active infection