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.

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

Exclusion Criteria:

* Pregnancy, lactation, or breastfeeding.
* 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.
* History or clinical evidence of central nervous system (CNS) primary tumors or metastases.
* Participants with another invasive malignancy in the last two years.
* Participants with known active or uncontrolled infection.
* Positive HIV test at screening.
* Positive for Hepatitis B and C.
* Vaccination with live vaccines within 28 days prior to C1D1.
* Major surgical procedure or significant traumatic injury within 28 days prior to first RO7296682 and atezolizumab infusion.
* Participants with wound healing complications.
* Dementia or altered mental status that would prohibit informed consent.
* History of Stevens-Johnson syndrome, toxic epidermal necrolysis, or DRESS (drug rash with eosinophilia and systemic symptoms).
* Active or history of autoimmune disease or immune deficiency.
* 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.
* 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.
* 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).