Study of Cobimetinib in Combination With Atezolizumab and Bevacizumab in Participants With Gastrointestinal and Other Tumors

Inclusion Criteria:

- Eastern Cooperative Oncology Group performance status of 0 or 1

- Histologically confirmed unresectable metastatic colorectal adenocarcinoma

- Life expectancy at least 12 weeks

- Progression on a prior line of therapy that contained a fluoropyrimidine and
oxaliplatin or irinotecan for unresectable metastatic colorectal adenocarcinoma

- Measurable disease per RECIST v1.1

- Adequate hematologic and end organ function

- Creatinine clearance greater than or equal to (>=) 30 milliliters per minute (mL/min)

- For biopsy cohort, participants must be bevacizumab naive or received the last
bevacizumab treatment at least 12 months prior to Cycle 1 Day 1 and according to the
investigator's judgment the planned biopsies would not expose participants to
substantially increased risk of complications

- For women of childbearing potential, agreement to remain abstinent (refrain from
heterosexual intercourse) or use of contraceptive methods that result in a failure
rate of less than (<) 1 percent (%) per year during the treatment period and for at
least 180 days after the last study treatment

- For men, agreement to remain abstinent (refrain from heterosexual intercourse) or use
contraceptive measures, and agreement to refrain from donating sperm

Exclusion Criteria:

- More than one prior line of systemic therapy for advanced CRC

- Participants with known microsatellite (MSI)-high status

- Major surgery or significant traumatic injury within 60 days prior to enrollment

- Minor surgical procedure within 15 days of study Cycle 1 Day 1

- Untreated central nervous system (CNS) metastases

- Treatment with any investigational agent or approved therapy within 28 days

- Malignancies other than colorectal cancer within 5 years prior to Cycle 1 Day 1

- Prior radiation therapy within 30 days prior to study Cycle 1 Day 1 and/or persistence
of radiation-related adverse effects

- Prior allogeneic bone marrow transplantation or solid organ transplant for another
malignancy in the past

- Spinal cord compression not definitively treated with surgery and/or radiation

- Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent
drainage procedures

- Current or recent use of therapeutic oral or parenteral anticoagulants or thrombolytic
agents

- Intake of St. John's wort or hyperforin (potent cytochrome P450 [CYP] 3A4 enzyme
inducer) or grapefruit juice (potent CYP3A4 enzyme inhibitor) within 7 days prior to
initiation of study treatment

- History of severe allergic, anaphylactic, or other hypersensitivity reactions to
chimeric or humanized antibodies or fusion proteins

- Known hypersensitivity or allergy to biopharmaceuticals produced in Chinese hamster
ovary cells or any components of cobimetinib, atezolizumab, or bevacizumab
formulations

- Prior treatment with clusters of differentiation (CD) 137 (CD137) agonists or immune
checkpoint blockage therapies, anti-programmed death protein-1, anti-program
death-ligand 1, mitogen-activated protein kinase (MEK) inhibitor

- Proteinuria value > 1.0 g at screening

- Uncontrolled glaucoma with intraocular pressure ≥ 21 mmHg

- Hyperglycemia (fasting) ≥ Grade 2

- Human Immunodeficiency Virus (HIV) infection

- Active hepatitis B or hepatitis C

- History of autoimmune disease, clinically significant cardiac or pulmonary dysfunction

- Administration of a live, attenuated vaccine within 4 weeks prior to Cycle 1 Day 1 or
at any time during the study and for at least 5 months after the last dose of study
drug

- History of or evidence of retinal pathology on ophthalmologic examination that is
considered a risk factor for neurosensory retinal detachment/central serous
chorioretinopathy, retinal vein occlusion, or neovascular macular degeneration

- History of idiopathic pulmonary fibrosis, organizing pneumonia, drug-induced
pneumonitis, or idiopathic pneumonitis

- Uncontrolled tumor pain