Phase 3 Study of Toripalimab Alone or in Combination With Tifcemalimab as Consolidation Therapy in Patients With Limited-stage Small Cell Lung Cancer (LS-SCLC)

Prior treatment

• Received sequential chemoradiotherapy for LS-SCLC.
• Failure to recover from toxicity of prior anticancer therapy to Common Terminology Criteria for Adverse Events (CTCAE) Grade ≤ 1 (except alopecia) or levels specified in the inclusion/exclusion criteria, whichever is more severe.
• History of confirmed or suspected interstitial lung disease or pneumonitis (except for Grade 1 radiation pneumonitis not treated with corticosteroids).
• Any other malignancy diagnosed prior to the first dose of investigational intervention, except those with a low risk for the development of metastases (5-year survival rate \> 90%), such as adequately treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix or breast, or adequately treated localized prostate cancer.

Other illness

• Mixed SCLC and non-small cell lung cancer (NSCLC).
• Patients with active autoimmune disease, history of autoimmune disease.
• History of immunodeficiency, including HIV seropositivity, other acquired congenital immunodeficiency diseases, or a history of organ transplantation or allogeneic bone marrow transplantation.
• The presence of active hepatitis B (HBV DNA ≥ 500 IU/mL), hepatitis C (hepatitis C antibodies positive and HCV-RNA higher than the lower limit of detection of the analytical method).

Other

• Patients will be excluded from the study if they meet any of the following criteria.
• Women who are pregnant or breastfeeding.

• Patients must meet all of the following inclusion criteria to be enrolled:
• Male or female with age ≥ 18 years old at the time of informed consent.
• Histologically or cytologically confirmed LS-SCLC using the Veteran's Administration Lung Study Arm (VALSG) staging criteria (Appendix 3). Patients with TNM Stage I or II disease per AJCC 8th edition must be medically inoperable (as determined by the Investigator) or the patient must refuse surgery.
• Received CRT defined as: (1) 4 cycles of chemotherapy consisting of carboplatin or cisplatin and intravenously administered etoposide; (2) a total radiation dose of 60-66 Gy for the standard once daily (QD) radiotherapy regimen or 45 Gy for the hyperfractionated twice daily (BID) radiotherapy regimen; (3) Patients must begin investigational interventions within 42 days of the last dose of chemotherapy.
• Patients must have achieved a complete response (CR), partial response (PR), or stable disease (SD) after receiving curative platinum-based CRT and must not have developed progressive disease (PD) prior to study entry.
• Eastern Cooperative Oncology Group (ECOG) performance status (PS) score of 0-1 .
• Adequate organ function
• Female patients of childbearing potential and male patients whose partners are women of childbearing age.
• Voluntarily agree to participate in the study, sign the informed consent form, and agree to comply with all study and follow-up procedures.