This study evaluates the efficacy and safety of Firmonertinib 160 mg once daily in patients with EGFR-mutant, advanced NSCLC who achieve stable disease after first-line Firmonertinib 80 mg for 8 weeks.

Inclusion Criteria:

• Age 18-75 years.
• ECOG performance status 0-1; life expectancy ≥3 months.
• Histologically/cytologically confirmed advanced/metastatic non-squamous NSCLC unsuitable for curative therapy.
• Documented EGFR 19del or L858R mutation.
• No prior systemic therapy for advanced disease.
• Stable disease after 8 weeks of Firmonertinib 80 mg daily.
• more than 1 measurable lesion per RECIST v1.1.
• Adequate hematologic, renal, hepatic, and coagulation function.
• Signed written informed consent.

Exclusion Criteria:

• Hypersensitivity to Firmonertinib or related compounds.
• Other actionable oncogenic drivers (ALK, ROS1, RET, BRAF, NTRK, MET, KRAS, except TP53/RB1).
• Prior EGFR-TKI therapy or prohibited concomitant medications.
• Unresolved toxicities >CTCAE Grade 1 (except allowed conditions).
• Symptomatic CNS metastases or spinal cord compression.
• GI disorders impairing drug absorption.
• Uncontrolled systemic diseases or active infections (HBV/HCV/HIV).
• Interstitial lung disease (history or active).
• Clinically significant cardiac abnormalities including QTc >470 ms or LVEF <50%.
• Pregnancy or breastfeeding.
• Any condition compromising compliance.
• CR, PR, or PD at completion of induction therapy.