The aim of the study is to evaluate the efficacy and safety of SKB264 in combination with pembrolizumab as firstline treatment for patients with PD-L1-positive locally advanced or metastatic non-small cell lung cancer (NSCLC).

This is a randomized, open-label, multicenter, Phase 3 study to evaluate the efficacy and safety of SKB264 in combination with pembrolizumab versus pembrolizumab as firstline treatment for PD-L1 positive patients with locally advanced or metastatic non-small cell lung cancer.

Inclusion Criteria:Key Inclusion Criteria:

1. Histologically or cytologically confirmed NSCLC that is locally advanced (Stage ⅢB/ⅢC) or metastatic (Stage IV) NSCLC that is not amenable to radical surgery and/or radical radiotherapy regardless of concurrent chemotherapy.
2. No prior systemic anti-cancer therapy for locally advanced or metastatic disease.
3. Participants whose tumours are PD-L1 TPS ≥ 1%.
4. At least one measurable lesion per RECIST v1.1.
5. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 1 with no worsening within 7 days prior to randomization.
6. A life expectancy of at least 12 weeks.
7. Adequate organ and bone marrow function.

Exclusion Criteria:Key Exclusion Criteria:

1. Active second malignancy.

2. Uncontrolled or clinical significant cardiovascular disease.

3. History of noninfectious pneumonitis/interstitial lung disease (ILD) that required steroids or has current pneumonitis/ILD.

4. Active infection requiring systemic therapy within 2 weeks of randomization.

5. Active hepatitis B or hepatitis C virus infection.

6. Human immunodeficiency virus (HIV) positive or history of acquired immunodeficiency syndrome (AIDS); known active syphilis infection.

7. Known allergy to SKB264 or pembrolizumab or any of its components.

8. Prior treatment with any of the following (including in the context of adjuvant, neoadjuvant therapy):

   1. Immune checkpoint inhibitors (e.g., anti-PD-1/L1 antibody, anti-CTLA-4 antibody, etc.), checkpoint agonists (e.g., ICOS, CD40, CD137, GITR, OX40 antibody, etc.), any treatment targeting the immune mechanism of tumors such as immune cell therapy;
   2. Therapy targeting TROP2.
   3. Any drug therapy that targets topoisomerase I, including antibody-drug conjugates (ADCs).

9. Major surgery within 4 weeks prior to randomization or expected major surgery during the study.

10. Pregnant or lactating women.