Inclusion Criteria:
1. Male or female, ≥ 18 and ≤ 75 years at the time of signing the informed consent form (ICF).
2. Histologically or cytologically confirmed NSCLC.
3. No prior systemic anti-tumor therapy.
4. No prior local therapy for NSCLC.
5. Confirmed by tumor histology, or cytology to have EGFR sensitizing mutations.
6. Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 within 7 days before randomization.
7. At least one target lesion as assessed by the investigator according to RECIST v1.1.
8. Life expectancy ≥ 24 weeks.
9. Adequate organ and bone marrow function.
10. For female participants of childbearing potential and male participants with partners of childbearing potential, they must agree to use effective medical contraception from the start of signing the ICF until 6 months after the last dose.
11. Participants must voluntarily join this study, sign the ICF, and be able to comply with the protocol-specified visits and related procedures.
Exclusion Criteria:
1. Tumor histology or cytology confirming combined small cell lung cancer, neuroendocrine carcinoma, or carcinosarcoma or squamous cell carcinoma components of more than 10%.
2. Participants with other malignant tumors within 3 years prior to randomization.
3. Resting electrocardiogram (ECG) showing clinically significant abnormal results.
4. Presence of any of the following cardiovascular and cerebrovascular diseases or cardiovascular and cerebrovascular risk factors.
5. Uncontrolled systemic diseases in the investigator's judgment.
6. History of interstitial lung disease (ILD), drug-induced ILD, or non-infectious pneumonitis, have current ILD or non-infectious pneumonitis.
7. Clinically severe lung damage due to complications of lung disorder.
8. Participants who have received systemic corticosteroids therapy with \> 10 mg/day of prednisone or other immunosuppressive drugs within 2 weeks before randomization.
9. Known active pulmonary tuberculosis.
10. Known history of allogeneic organ transplant and allogeneic hematopoietic stem cell transplant.
11. Active hepatitis B.
12. Positive for human immunodeficiency virus (HIV) test or history of acquired immunodeficiency syndrome (AIDS); known active syphilis infection.
13. Known hypersensitivity to osimertinib, sacituzumab tirumotecan, or any of their components (including but not limited to polysorbate-20); known history of severe hypersensitivity to other biologics.
14. Have received a live vaccine within 30 days prior to randomization, or plan to receive a live vaccine during the study.
15. Pregnant or lactating women.
16. Any condition that, in the investigator's opinion, would interfere with the evaluation of the study drug, participant safety, or interpretation of study results, or any other condition that the investigator considers unsuitable for participation in this study.
