This study aims to evaluate the safety and tolerability of RO7673396 in participants with advanced solid tumors harboring RAS mutation(s). This study consists of two stages: Stage 1 (Dose Escalation) and Stage 2 (Dose Expansion). Stage 1 will define the recommended dose(s) for expansion (RDEs) of RO7673396. Stage 2 will evaluate preliminary anti-tumor activity of the RDE(s) defined in Stage 1 and of other doses of interest for future development in selected solid tumor indications.

DRUG: RO7673396

RO7673396 will be administered as per the schedule specified in the protocol.

• Histologically documented, locally advanced, recurrent, or metastatic incurable solid tumors
• Participants with measurable disease according to RECIST v1.1 assessed by the investigator
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• Life expectancy ≥12 weeks
• Adequate hematologic and end-organ function
• Confirmed presence of the RAS mutation(s)

• Refractory nausea and vomiting, malabsorption, external biliary shunt, or significant small bowel resection that would preclude adequate study treatment absorption
• Known and untreated, or active central nervous system (CNS) metastases
• Participants with chronic diarrhea, short bowel syndrome or significant upper gastrointestinal (GI) surgery including gastric resection, a history of inflammatory bowel disease (IBD)
• Treatment with chemotherapy, immunotherapy, biologic therapy, or an investigational agent as anti-cancer therapy within 4 weeks or five half-lives prior to initiation of study treatment
• Participants who are on acid-reducing agents and unable to safely discontinue them as required in the study
• Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent drainage procedures
• Known clinically significant liver disease