A Dose Escalation and Expansion Study of Lomvastomig, a PD-1/TIM-3 Bispecific Antibody, in Participants With Advanced and/or Metastatic Solid Tumors

Inclusion Criteria:

General Inclusion Criteria:

1. Part A: Patient must have histologically or cytologically confirmed advanced and/or metastatic solid tumor malignancies for which standard curative or palliative measures do not exist, are no longer effective, or are not acceptable to the patient
2. Eastern Cooperative Oncology Group Performance Status 0-1
3. Measurable disease as defined by Response Evaluation Criteria in Solid Tumors (RECIST v1.1)
4. Fresh biopsies may be required
5. Negative HIV, hepatitis B, or hepatitis C test result
6. Women of childbearing potential and male participants must agree to remain abstinent or use contraceptive methods as defined by the protocol

Additional Specific Inclusion Criteria for Participants with Melanoma:

1. Histologically confirmed, unresectable stage III or stage IV melanoma
2. Previously treated with approved anti-programmed death-ligand 1 (PD-L1)/anti-programmed death-1 (PD-1) agents with or without approved anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) therapy and up to one additional treatment regimen

Additional Specific Inclusion Criteria for Participants with Non-small Cell Lung Cancer (NSCLC) who Previously Received Treatment for Metastatic Disease:

1. Histologically confirmed advanced NSCLC
2. Previously treated with approved PD-L1/PD-1 inhibitors and platinum-based chemotherapy
3. Not more than 2 prior lines of treatment for metastatic disease are allowed prior to enrolling to the study
4. Participants must have experienced initial clinical benefit (stable disease or better) from most recent checkpoint inhibitor (CPI) therapy
5. Tumor PD-L1 expression as determined by immunohistochemistry assay of archival tumor tissue or tissue obtained at screening

Additional Specific Inclusion Criteria for Participants with Non-small Cell Lung Cancer (NSCLC) who Previously Did Not Receive Treatment for Metastatic Disease:

1. Histologically confirmed advanced NSCLC
2. Tumor PD-L1 expression as determined by immunohistochemistry assay of archival tumor tissue or tissue obtained at screening

Additional Specific Inclusion Criteria for Participants with Small Cell Lung Cancer (SCLC):

1. Histologically confirmed SCLC
2. Participants may have had prior chemotherapy, radiation therapy, or declined approved therapies for SCLC

Additional Specific Inclusion Criteria for Participants with Esophageal Squamous Cell Carcinoma (ESCC):

1. Participants whose major lesion was histologically confirmed as squamous cell carcinoma or adenosquamous cell carcinoma of the esophagus
2. Patients who have previously received not more than 1 prior line of treatment for metastatic disease prior to enrolling to the study

Exclusion Criteria:

General Exclusion Criteria:

1. Pregnancy, lactation, or breastfeeding
2. Known hypersensitivity to any of the components of RO7121661
3. Active or untreated central nervous system (CNS) metastases
4. An active second malignancy
5. Evidence of concomitant diseases, metabolic dysfunction, physical examination findings, or clinical laboratory findings giving reasonable suspicion of a disease or condition that contraindicates the use of an investigational drug or that may affect the interpretation of the results or render the participant at high risk from treatment complications
6. Known active or uncontrolled bacterial, viral, fungal, mycobacterial, parasitic, or other infection
7. Treatment with oral or IV antibiotics within 2 weeks prior to Cycle 1 Day 1
8. Active or history of autoimmune disease or immune deficiency
9. Prior treatment with adoptive cell therapies, such as CAR-T therapies
10. Concurrent therapy with any other investigational drug <28 days or 5 half-lives of the drug, whichever is shorter, prior to the first RO7247669 administration
11. Regular immunosuppressive therapy
12. Radiotherapy within the last 4 weeks before start of study drug treatment, with the exception of limited palliative radiotherapy
13. Prior treatment with a T-cell immunoglobulin and mucin domain-3 (TIM-3) inhibitor

Additional Specific Exclusion Criteria for Participants with NSCLC who Previously Received Treatment for Metastatic Disease:

- Patients with the following mutations, rearrangements, translocations are not eligible: epidermal growth factor receptor (EGFR); anaplastic lymphoma kinase (ALK); ROS proto-oncogene 1 (ROS1), BRAFV600E, and neurotrophic receptor tyrosine kinase (NTRK)

Additional Specific Exclusion Criteria for Participants with NSCLC who Did Not Previously Receive Treatment for Metastatic Disease:

1. Prior therapy for metastatic disease
2. Adjuvant anti-PD-1 or anti-PD-L1 therapy

Additional Specific Exclusion Criteria for Participants with Small-Cell Lung Cancer (SCLC):

- Prior therapy with any immune CPIs (such as anti-PD-L1/PD-1, CTLA-4)

Additional Specific Exclusion Criteria for Participants with Esophageal Squamous Cell Carcinoma (ESCC):

- Prior therapy with any immunomodulatory agents