A Study to Evaluate the Safety and Tolerability of RO7296682 in Combination With Atezolizumab in Participants With Advanced Solid Tumors.

Inclusion Criteria:

- Diagnosis of advanced and/or metastatic solid tumors who have progressed on a standard therapy, are intolerant to standard of care (SoC), and/or and non-amenable to SoC.

Participants whose tumors have known sensitizing mutations must have experienced disease progression (during or after treatment) or intolerance to treatment with a respective targeted therapy.

1. Measurable disease according to RECIST v1.1.
2. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0 or 1.
3. Able to provide the most recent archival tumor tissue samples.
4. Adequate cardiovascular, haematological, liver and renal function.
5. Participants on therapeutic anticoagulation must be on a stable anticoagulant regimen.
6. Women of Childbearing Potential: Agreement to remain abstinent (refrain from heterosexual intercourse) or use highly effective contraceptive methods.
7. Men: Agreement to remain abstinent (refrain from heterosexual intercourse) or use highly effective contraceptive methods and refrain from donating sperm.

Exclusion Criteria:

1. Pregnancy, lactation, or breastfeeding.
2. Known hypersensitivity to any of the components of RO7296682 and atezolizumab, including but not limited to hypersensitivity to Chinese hamster ovary cell products or other recombinant human or humanized antibodies.
3. History or clinical evidence of central nervous system (CNS) primary tumors or metastases.
4. Participants with another invasive malignancy in the last two years.
5. Participants with known active or uncontrolled infection.
6. Positive HIV test at screening.
7. Positive for Hepatitis B and C.
8. Vaccination with live vaccines within 28 days prior to C1D1.
9. Major surgical procedure or significant traumatic injury within 28 days prior to first RO7296682 and atezolizumab infusion.
10. Participants with wound healing complications.
11. Dementia or altered mental status that would prohibit informed consent.
12. History of Stevens-Johnson syndrome, toxic epidermal necrolysis, or DRESS (drug rash with eosinophilia and systemic symptoms).
13. Active or history of autoimmune disease or immune deficiency.
14. Prior treatment with CPIs (e.g. anti-CTLA4, anti-PD1, anti-PDL1), immunomodulatory monoclonal antibodies (mAbs) and/or mAb-derived therapies (approved or investigational) is approved.
15. Treatment with standard radiotherapy, any chemotherapeutic agent, targeted therapy or treatment with any other investigational drug (defined as treatment for which there is currently no regulatory authority-approved indication) within 28 days or 5 half-lives of the drug (whichever is shorter), prior to the first RO7296882 administration on C1D1.
16. Radiotherapy within the last 4 weeks before start of study drug treatment, with the exception of limited palliative radiotherapy (for which no wash out period is required).