This is a Phase Ib/II study. The objectives are to evaluate the safety/tolerability and efficacy of GFH925 in combination with Cetuximab in advanced KRAS G12C mutant NSCLC, to characterize pharmacokinetics (PK) of GFH925 in combination with Cetuximab in advanced KRAS G12C mutant NSCLC

Inclusion Criteria:

1. Patient has provided informed consent form (ICF).
2. Males or females aged ≥ 18 years.
3. Eastern Cooperative Oncology Group (ECOG) Performance Status of 0~1.
4. Life expectancy > 3 months judged by the investigator.
5. Have histologically or cytologically confirmed advanced KRAS G12C-mutated NSCLC.
6. Have at least one measurable lesion per RECIST 1.1.
7. Have sufficient organ functions.
8. With toxicities left from prior anti-tumor therapy resolved to baseline or CTCAE Grade 1 (neurotoxicity or alopecia ≤ Grade 2).
9. Women of childbearing potential (WOCBP) and male patients with WOCBP partners must agree to use effective contraception method during the study specified period.

Exclusion Criteria:

1. With clinically significant cardiovascular diseases.
2. With active central nervous system (CNS) metastases and/or carcinomatous meningitis.
3. With clinically significant gastrointestinal diseases.
4. With active infections.
5. With uncontrollable or symptomatic pleural effusion, ascites, or pericardial effusion.
6. With uncontrolled systemic diseases, such as hypertension or diabetes.
7. Prior treatment with an inhibitor specific to KRAS G12C.
8. Major surgery within 4 weeks prior to initiation of study treatment.
9. With known allergies to the study drugs or components.
10. Pregnant or lactating females, or female patients intend to become pregnant during participation.