The purpose of this study is to assess the efficacy, safety, pharmacokinetics (PK), and pharmacodynamics of two dose levels of RO7247669 in participants with unresectable or metastatic melanoma to select the recommended dose for further development.

Inclusion Criteria:

• Histologically confirmed unresectable or metastatic melanoma, per the American Joint Committee on Cancer (AJCC) staging system (unresectable Stage III or Stage IV)
• Radiologically measurable disease according to Response Evaluation Criteria in Solid Tumors (RECIST) v1.1
• Eastern Cooperative Oncology Group (ECOG) Performance Status 0-1
• Known v-Raf murine sarcoma viral oncogene homolog B1 (BRAF) V600 mutation status
• Adequate cardiovascular, hematological, hepatic and renal function
• Willingness to abide by contraceptive measures for the duration of the study
• Participants must have known PD-L1 status

Exclusion Criteria:

• Pregnancy, lactation, or breastfeeding
• Known hypersensitivity to any of the components of RO7247669
• Participants must not have ocular melanoma
• Symptomatic central nervous system (CNS) metastases
• Significant cardiovascular/cerebrovascular disease within 6 months prior to randomization
• Known active or uncontrolled bacterial, viral, fungal, mycobacterial, parasitic, or other infection or any major episode of infection requiring treatment with intravenous (IV) antibiotics or hospitalization within 28 days prior to randomization
• Major surgical procedure or significant traumatic injury (excluding biopsies) within 28 days prior to randomization, or anticipation of the need for major surgery during the course of the study
• Active or history of autoimmune disease or immune deficiency with some exceptions
• Prior systemic anticancer therapy for unresectable or metastatic melanoma
• Prior anticancer therapy with any-immunomodulatory agents including CPIs (such as anti-programmed death-ligand 1[PD-L1]/PD-1 and anti-cytotoxic T lymphocyte-associated antigen [CTLA-4]) with some exceptions if used as prior adjuvant or neoadjuvant melanoma therapies
• Prior treatment with anti-LAG3 therapy

For eligible studies, qualified researchers may request access to individual patient level clinical data. See Roche's commitment to transparency of clinical study information here: https://go.roche.com/data\_sharing