This study will determine the maximum tolerated dose and the dose limiting toxicities (Part 1 of study) and the activity (Part 2 of study) of RO5126766 in patients with metastatic or advanced solid tumors. In the first part of the study, groups of patients will by sequentially enrolled to receive ascending oral doses of RO5126766 daily for 28 days. The starting dose of 0.1mg will be escalated in subsequent groups of patients after a successful assessment of the safety and tolerability of the previous dose. In Part 2 of the study, patients with selected tumor types will be randomized to receive either the optimal biological dose or the maximum tolerated dose of RO5126766 daily. The anticipated time on study treatment is until disease progression, and the target sample size is 100 individuals.

Inclusion Criteria:

• adult patients, >=18 years of age;
• advanced and/or metastatic cancer not amenable to standard therapy;
• any solid tumor type (Part 1); malignant melanoma, pancreatic cancer or non-small cell lung cancer (Part 2);
• measurable and/or evaluable disease (Part 1), >=1 measurable lesion (Part 2);
• ECOG performance status 0-1.

Exclusion Criteria:

• prior chemotherapy, radiotherapy or immunotherapy within 28 days of first receipt of study drug;
• prior corticosteroids as anti-cancer therapy within 14 days of first receipt of study drug;
• known past or present CNS metastases;
• acute or chronic infection.