Inclusion Criteria: - Histologically confirmed diagnosis of a solid tumor malignancy with any of the following oncogenic mutations detected in tumor tissue or ctDNA by a sponsor-approved test: 1. MRTX0902 monotherapy: known KRAS mutations, known annotated recurrent activating SOS1, PTPN11, class III BRAF, or EGFR mutation, or known annotated recurrent inactivating NF1 mutation; 2. MRTX0902 and adagrasib combination therapy: KRAS G12C mutation. - Unresectable or metastatic disease - No available treatment with curative intent; standard treatment is not available or patient declines - Presence of tumor lesions to be evaluated per RECIST 1.1: 1. Phase 1 dose escalation, RECIST 1.1 measurable or evaluable disease 2. Phase 1b and Phase 2 cohorts, RECIST 1.1 measurable disease - Presence of a tumor lesion amenable to mandatory biopsy for pharmacodynamic evaluation at baseline and on-study unless Sponsor-confirmed as medically unsafe or infeasible. - Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1. - Adequate organ function Exclusion Criteria: - Active brain metastases or carcinomatous meningitis - Prior treatment with a KRAS G12C inhibitor (for Phase 1b expansion for MRTX0902 and adagrasib combination, and Phase 2 cohorts only) - History of significant hemoptysis or hemorrhage within 4 weeks of the first dose of study treatment. - Major surgery within 4 weeks of first dose of study treatment - History of pneumonitis or interstitial lung disease - Ongoing need for medication with following characteristics: substrate of CYP3A; strong inducer or inhibitor or CYP3A and/or P-gp; strong inhibitors of BRCP and proton pump inhibitors - Cardiac abnormalities - History of intestinal disease, inflammatory bowel disease, major gastric surgery, or other gastrointestinal conditions (eg, uncontrolled nausea, vomiting, malabsorption syndrome) likely to alter absorption of study treatment or result in inability to swallow oral medications