This open-label 2-arm study will assess the pharmacokinetics, pharmacodynamics, safety and efficacy of RO5429083 in patients with metastatic and/or locally advanced CD44-expressing malignant solid tumors. In Part A, cohorts of patients will receive RO5429083 intravenously at escalating doses. In Part B, patients will receive 89Zr-labelled RO5429083 in Cycles 1 and/or 2, followed by RO5429083. For all patients there will be an option to continue treatment with RO5429083 until disease progression or unacceptable toxicity occurs.

Inclusion Criteria:

• Adult patients, >/= 18 years of age
• Metastatic and/or locally advanced malignant CD44-expressing solid tumors
• Patients with disease progression on standard therapy, or have tumors that are not curable by standard therapy
• Life expectancy of over 12 weeks

Exclusion Criteria:

• Concurrent therapy with any other investigational drug
• Known or suspected CNS metastases including leptomeningeal metastases
• Active bleeding, bleeding diathesis or history of coagulation disorder
• Uncontrolled diabetes mellitus
• Active or uncontrolled infections
• Patients with HIV infections