A Study of Cobimetinib Plus Atezolizumab Versus Pembrolizumab in Participants With Previously Untreated Advanced BRAFv600 Wild-Type Melanoma

Inclusion Criteria: Disease-Specific Inclusion Criteria * Histologically confirmed locally advanced and unresectable or metastatic melanoma * Naive to prior systemic anti-cancer therapy for melanoma * Documentation of BRAFV600 wild-type status in melanoma tumor tissue through use of a clinical mutation test approved by the local health authority * A representative, formalin-fixed, paraffin-embedded (FFPE) tumor specimen in a paraffin block (preferred) or 20 slides containing unstained, freshly cut, serial sections must be submitted along with an associated pathology report prior to study entry. If 20 slides are not available or the tissue block is not of sufficient size, the patient may still be eligible for the study, after discussion with and approval by the Medical Monitor * Measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 * Age \>=18 years at time of signing Informed Consent Form * Ability to comply with the study protocol, in the investigator's judgment * Histologically or cytologically confirmed BRAFV600 wild-type melanoma * Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1 * Life expectancy \>=3 months * Adequate hematologic and end-organ function * For women of childbearing potential: agreement to remain abstinent or use at least two forms of effective contraceptive with a failure rate of \< 1% per year during the treatment period and for at least 3 months after the last dose of cobimetinib and at least …