This is a Two-cohort, Exploratory Clinical Study Assessing the Activity of Benmelstobart Combined With Chemotherapy With or Without Anlotinib in Resectable Limited-Stage Small Cell Lung Cancer

Inclusion Criteria: * Patients voluntarily participate in this study, sign the informed consent form, demonstrate good compliance, and cooperate with follow-up. * Aged 18 to 75 years (inclusive) at the time of signing informed consent, regardless of gender. * Histologically confirmed small cell lung cancer (SCLC). * Confirmed as stage I-IIIB SCLC (T1-3N0-2M0) per AJCC 9th Edition. * Patients who have received 1 cycle of chemotherapy are eligible; no other prior treatments are permitted. * ECOG Performance Status (PS) 0 or 1. * Assessed by the investigator as having no surgical contraindications. * At least one measurable lesion per RECIST 1.1 criteria. * Expected survival ≥8 weeks. * Women of childbearing potential (aged 15-49) must have a negative serum pregnancy test within 7 days before treatment initiation and agree to use reliable contraception during the study until 8 weeks after discontinuation. Normal function of major organs meeting the following criteria: * Hematologic tests (no blood transfusion, blood products, G-CSF, or hematopoietic stimulants within 14 days): Hemoglobin (Hb) ≥90 g/L; Absolute neutrophil count (ANC) ≥1.5×10⁹/L; Platelets (PLT) ≥80×10⁹/L. * Biochemical tests meeting: Total bilirubin (TBIL) ≤1.5×ULN; ALT/AST ≤2.5×ULN; Serum creatinine (Cr) ≤1.5×ULN or creatinine clearance (CCr) ≥60 mL/min. * Urine protein \<2+; for patients not on anticoagulation: INR ≤1.5, APTT ≤1.5×ULN. Patients on full-dose or parenteral anticoagulants may enroll if dosing has been stable for ≥2 weeks and coagulation tests are within therapeutic ranges. Exclusion Criteria: * Histologically confirmed mixed-type SCLC. * Extensive-stage SCLC. * ECOG PS \>1. * Active or untreated CNS metastases confirmed by CT/MRI during screening/prior imaging. * Uncontrolled tumor-related pain. * Uncontrolled pleural effusion, pericardial effusion, or ascites requiring recurrent drainage (≥1×/month). * Uncontrolled/symptomatic hypercalcemia (ionized calcium \>1.5 mmol/L, calcium \>12 mg/dL, or corrected serum calcium \>ULN). * Systemic immunostimulants (e.g., IFN-α, IL-2, TNF) within 4 weeks prior to enrollment (cancer vaccines allowed if prior). * Systemic corticosteroids (\>10 mg prednisone/day or equivalent) or immunosuppressants within 14 days, except: Replacement therapy (≤10 mg prednisone/day); Topical/ocular/intra-articular/nasal/inhaled steroids with minimal systemic absorption; Short-term (≤7 days) prophylactic use (e.g., contrast allergy) or for non-autoimmune conditions. * Imaging-confirmed tumor invasion of major vessels or high risk of fatal hemorrhage per investigator; or cavitary/necrotic lung tumors. * Other malignancies within 5 years except: cervical CIS, cured basal cell carcinoma, Ta/Tis bladder tumors. * Prior use of anlotinib or other antiangiogenic agents. * Prior anti-PD-1/PD-L1/CTLA-4 antibodies or other T-cell co-stimulation/checkpoint pathway therapies (e.g., ICOS, CD40/CD137/GITR/OX40 agonists). * Hypersensitivity to anlotinib or benmelstobart components. * Factors impairing oral drug intake (e.g., dysphagia, chronic diarrhea, intestinal obstruction). * Uncontrolled comorbidities including: 1. Poorly controlled hypertension (SBP ≥150 mmHg, DBP ≥100 mmHg); 2. Grade ≥1 myocardial ischemia/infarction, arrhythmias (QTc ≥480 ms), or ≥NYHA Class II heart failure; 3. Abnormal coagulation (INR \>1.5, PT \>ULN+4s, APTT \>1.5×ULN), bleeding tendency, or thrombolytic/anticoagulant therapy (prophylactic low-dose heparin \[6,000-12,000 U/day\] or aspirin \[≤100 mg/day\] allowed if INR ≤1.5); 4. Active/severe uncontrolled infections; 5. Cirrhosis, decompensated liver disease, active/chronic hepatitis requiring antivirals; 6. Renal failure requiring dialysis; 7. Immunodeficiency (HIV+, congenital/acquired immunodeficiency) or organ transplant history; 8. Poorly controlled diabetes (FBG \>10 mmol/L); 9. Urine protein ≥++ or 24-h urine protein \>1.0 g; 10. Epilepsy requiring treatment; 11. Non-healing wounds/fractures. * Significant hemoptysis (\>50 mL/day within 2 weeks) or clinically significant bleeding (e.g., GI bleeding, hemorrhagic gastric ulcer, baseline fecal occult blood ≥++). * Interstitial lung disease (ILD), drug-induced ILD, steroid-requiring radiation pneumonitis, or active ILD. * Arterial/venous thromboembolism within 6 months (e.g., stroke \[including TIA\], DVT, PE). * Grade ≥2 peripheral neuropathy (excluding trauma-related). * Major surgery/severe trauma with residual effects within 14 days. * Concurrent clinical trials or \<4 weeks from prior trial treatment. * Live/attenuated vaccination within 30 days before benmelstobart or planned during study. * History of severe hypersensitivity to monoclonal antibodies. * Pregnant/lactating women. * Uncontrolled psychiatric/neurological disorders affecting compliance. * Other factors per investigator judgment that may lead to study termination (e.g., severe illness, lab abnormalities, or social/family constraints compromising safety/data collection).