Sacituzumab Tirumotecan in Combination With Furmonertinib as Second-line Treatment for EGFR-mutant Advanced or Metastatic NSCLC After Failure of First-line Third-generation EGFR-TKI Therapy

Inclusion Criteria: * 1\. Aged 18 to 75 years at the time of signing the informed consent form, regardless of gender; 2. Histologically or cytologically confirmed non-squamous NSCLC, which is locally advanced (Stage ⅢB/ⅢC) or metastatic (Stage Ⅳ) NSCLC that is not suitable for radical surgery and/or radical radiotherapy (whether concurrent chemotherapy is administered or not) \[according to the 8th Edition of the Lung Cancer TNM Staging System by the Union for International Cancer Control (UICC) and the American Joint Committee on Cancer (AJCC)\]; 3. There must be medical records showing evidence of previous EGFR mutation test results (known presence of EGFR mutations sensitive to EGFR-TKI \[Ex19del, L858R\], which may exist alone or concurrently with other EGFR mutations, possibly including T790M); 4. Subjects who experienced extracranial radiological progression after achieving remission (CR or PR) or stable disease (SD ≥ 6 months) during the first-line treatment with third-generation EGFR-TKI, but have not received further subsequent treatment (for subjects who received first-line treatment with a third-generation EGFR-TKI other than furmonertinib, the interval between the last dose of the first-line third-generation EGFR-TKI and the first dose of this study must be at least 8 days); 5. The brain metastasis status of subjects at enrollment must meet one of the following conditions: 1. No brain metastasis; 2. Stable brain metastasis, defined as no central nervous system (CNS) symptoms; or clinically stable for at least 4 weeks before enrollment, with all CNS symptoms returned to the baseline state; no evidence of new or enlarged brain metastatic lesions; and no need for treatment with glucocorticoids or anticonvulsants for at least 2 weeks before enrollment; 6. According to RECIST v1.1, the investigator assesses that there is at least one measurable target lesion that has not been irradiated, is non-central nervous system, and is measurable (if a subject has only one measurable lesion and must undergo tissue biopsy, the baseline tumor assessment needs to be performed at least 14 days after the screening biopsy); 7. Eastern Cooperative Oncology Group (ECOG) Performance Status Score (see Appendix 1 for details) of 0 or 1; Exclusion Criteria: * 1\. Tumor histologically or cytologically confirmed to be combined with small cell lung cancer, neuroendocrine carcinoma, carcinosarcoma components, or squamous cell carcinoma components; 2. Radiologically diagnosed central nervous system (CNS) progression that occurred during or after previous first-line treatment with third-generation EGFR-TKI; 3. Subjects with known meningeal metastasis, brainstem metastasis, spinal cord metastasis and/or compression, or active central nervous system (CNS) metastasis; 4. Subjects who have previously received systemic antineoplastic therapy (such as chemotherapy and immunotherapy) for locally advanced or metastatic non-squamous NSCLC other than third-generation EGFR-TKI; 5. Previous treatment with TROP2-targeted therapy or any drug therapy targeting topoisomerase Ⅰ, including antibody-drug conjugate (ADC) therapy (including in the context of adjuvant or neoadjuvant therapy); 6. Radiotherapy with a total dose of \> 30 Gy administered to lung lesions within 6 months before the first dose; non-thoracic radiotherapy or extensive radiotherapy with a total dose of \> 30 Gy administered within 4 weeks before the first dose; palliative radiotherapy for symptom control is allowed, but it must be completed at least 2 weeks before the first dose; 7. History of other malignant tumors within 3 years before the first dose (except for tumors cured by local treatment, such as cutaneous basal cell carcinoma, cutaneous squamous cell carcinoma, carcinoma in situ of the cervix, etc.);