A Prospective Phase II Clinical Trial Evaluating the Efficacy and Safety of Adebrelimab in Combination With Trastuzumab Rezetecan for Patients With Stage III Unresectable HER2-Positive NSCLC

Inclusion Criteria: * Aged 18-75 years, male or female. * Histologically or cytologically confirmed stage III unresectable NSCLC per AJCC 9th edition, judged unresectable by institutional MDT team. * Confirmed HER2 alteration: HER2 mutation/amplification detected by tissue NGS, or HER2 protein overexpression (IHC 2+ or 3+). * No prior systemic anti-tumor therapy for NSCLC; prior anti-tumor Chinese herbal medicine allowed if ≥2 weeks washout before first dose. * At least 1 measurable target lesion per RECIST v1.1. * ECOG performance status 0 or 1. * Able to provide tumor tissue specimen (archival ≤6 months or newly biopsied non-irradiated lesion). * FEV1 \>1.0 L and FEV1% predicted \>40% within past 3 months. * Adequate organ function within 7 days before first dose (no blood product/G-CSF support within 14 days): * Hematology: WBC ≥3.0×10⁹/L, ANC ≥1.5×10⁹/L, PLT ≥100×10⁹/L, Hb ≥90g/L * Liver: AST/ALT ≤2.5×ULN (≤5×ULN for liver metastasis), TBIL ≤1.5×ULN * Renal: Serum Cr ≤1.5×ULN or CrCl ≥50 mL/min * Cardiac: LVEF ≥50% by echocardiogram * Fertile male/female participants must use effective contraception during treatment and 6 months after last dose; female participants non-lactating, negative serum HCG within 14 days pre-first dose. * Voluntarily sign written informed consent, good compliance for follow-up. Exclusion Criteria: * Mixed small cell/large cell neuroendocrine/sarcomatoid NSCLC histology. * Concurrent other actionable driver gene alterations (EGFR, ALK, MET, BRAF, RET etc.) besides HER2. * Past or concurrent other malignant tumor (except fully resected cancer ≥5 years without active treatment). * Prior thoracic radiotherapy. * Major surgery within 28 days or minor invasive surgery within 7 days before first dose. * HIV infection, active hepatitis B/C, organ transplant history, congenital/acquired immunodeficiency. * Systemic immune modulators (thymosin, interferon, IL-2) within 4 weeks pre-enrollment. * Uncontrolled severe cardiovascular disease, unstable angina or intervention-required ventricular arrhythmia within 1 month. * Confirmed or suspected interstitial lung disease, severe baseline pulmonary dysfunction interfering with lung toxicity monitoring. * Active uncontrolled ≥2 grade infection within 2 weeks before enrollment. * Active tuberculosis under treatment. * Known hypersensitivity to any component of study drugs or other monoclonal antibodies/fusion proteins. * Any condition judged by investigator to compromise participant safety or trial compliance.