This study will evaluate the efficacy, safety and tolerability of HS-20093 compared with active surveillance as consolidation therapy after chemoradiotherapy in participants with limited-stage small cell lung cancer.

This is a randomized, controlled, open-label, multi-center, phase III clinical study to evaluate the efficacy and safety of HS-20093 versus active surveillance as consolidation therapy in participants with limited-stage small cell lung cancer (LS-SCLC) who have not progressed after receiving chemoradiotherapy (CRT).

This study consists of an experimental arm and a control arm. The experimental arm will be administered HS-20093, and the control arm will only receive active surveillance. Efficacy and safety were assessed in both arms by follow-up analyses.

Inclusion Criteria:

1. Have signed Informed Consent Form.
2. Males or females ≥18 years old.
3. Patients with limited-stage SCLC who are deemed unsuitable for surgery or decline surgery.
4. ECOG performance status of 0-1.
5. Patients who have received CRT and have not progressed.
6. Minimum life expectancy > 12 weeks.
7. Males or Females should be using adequate contraceptive measures throughout the study.
8. Females must not be pregnant at screening or have evidence of non-childbearing potential.

Exclusion Criteria:

1. Patients with mixed SCLC or NSCLC or sarcoma-like carcinoma, or large cell neuroendocrine carcinoma.

2. Patients with extensive-stage SCLC.

3. Disease progression during CRT or before randomization.

4. Received or are receiving the following treatments:

   1. For LS-SCLC, prior treatment with or current use of other chemotherapy regimens other than platinum plus etoposide
   2. Received any other anti-cancer treatment.
   3. Previous or current treatment with B7-H3 target therapy.
   4. Traditional Chinese medicine indicated for tumors within 2 weeks prior to the first dose of study drug.
   5. Major surgery within 4 weeks prior to the first dose of study drug.

5. Interstitial lung disease (ILD)/non-infectious pneumonitis.

6. History of other primary malignancies.

7. Inadequate bone marrow reserve or organ functions.

8. Severe, uncontrolled or active cardiovascular disorders.

9. Severe or uncontrolled diabetes.

10. Serious or poorly controlled hypertension.

11. Severe bleeding symptoms or bleeding tendencies within 1 month prior to randomization.

12. Severe arteriovenous thrombosis occurred within 3 months prior to randomization.

13. Serious infection within 4 weeks prior to randomization.

14. Presence of Grade ≥ 2 toxicities due to prior anti-tumor therapy.

15. Having serious neurological or mental disorders.

16. History of hypersensitivity to any component of HS-200093 or its similar drugs.

17. Participants with any condition that compromises the safety of the participant or interferes with the assessment of the study, as judged by the investigator.