Key exclusion criteria

•No previous cancer therapy (chemotherapy, radiation therapy, immunotherapy, or biologic therapy) •Prior malignancy except for the following: adequately treated basal cell or squamous cell skin cancer, in situ cervical cancer, thyroid cancer (except anaplastic), or any cancer from which the patient has been disease-free for 2 years •Any major surgery within the last 3 weeks •Uncontrolled diabetes, hypertension, or other medical conditions that may interfere with the assessment of toxicity •Current use of anticoagulants (warfarin, heparin, direct thrombin inhibitors) at therapeutic levels •History of uncontrolled cardiovascular or interstitial lung disease and evidence or risk of retinal vein occlusion or central serous retinopathy •Subjects with conditions requiring systemic treatment with corticosteroids (>10 mg daily prednisone equivalents) or other immunosuppressive medications within 14 days of treatment. •Prior BRAF- or MEK-targeted therapy; patients who have received prior interferon are eligible •History of retinopathy or any finding at the ophthalmologic examination that is considered a risk factor for neurosensory retinal detachment/central serous chorioretinopathy, retinal vein occlusion, or neovascular macular degeneration •Prior BRAF- or MEK-targeted therapy; patients who have received prior interferon are eligible. •History of ocular/uveal/mucosal melanoma •Presence of any of the following risk factors for retinal vein occlusion:  O Uncontrolled glaucoma with intra-ocular pressures ≥21 mmHg  O Serum cholesterol grade ≥2;  O Hypertriglyceridemia grade ≥2  O Hyperglycemia (fasting) grade ≥2 •Correct QT interval >450 ms to baseline, history of congenital long QT syndrome •Uncontrolled medical conditions, among which endocrine disorders (such as hypothyroidism, hyperthyroidism, and diabetes) •Other severe medical or psychiatric conditions (e.g., depression) or abnormalities of laboratory tests that may increase the risk associated with study participation or the assumption of vemurafenib, atezolizumab, and cobimetinib or that may interfere with the interpretation of study results, which in the judgment of the Investigator can make the patient not eligible for the study •Uncontrolled intercurrent illness, including but not limited to: ongoing or active infection, symptomatic congestive heart failure, uncontrolled hypertension, unstable angina pectoris, cardiac arrhythmia, cerebrovascular accident or transient ischemic attack, pulmonary embolism, interstitial lung disease, chronic gastrointestinal serious conditions associated with diarrhea or psychiatric illness/social situations that would limit compliance with study requirement, substantially increase risk of incurring adverse events or compromise the ability of the patient to give written informed consent •History of active primary immunodeficiency •Receipt of live attenuated vaccine within 30 days before the first dose. Note: enrolled patients should not receive a live vaccine while receiving study treatments and up to 30 days after the last dose of study treatment •Prior treatment with an anti-PD-1, anti-PD-L1, anti-PD-L2, or anti-CTLA-4 antibody •Known allergy or hypersensitivity to any of the study drugs or any of the study drug excipients •Positive test for HBV sAg or hepatitis C virus ribonucleic acid (hepatitis C virus antibody) indicating acute or chronic infection •Known history of testing positive for HIV or known AIDS •Judgment by the investigator that the patient is unsuitable to participate in the study and the patient is unlikely to comply with study procedures, restrictions, and requirements.