This exploratory trial aims to determine if it is safe to use radiotherapy and lurbinectedin to treat SCLC with Single-lesion progression after first course treatment. Lurbinectedin kills tumor cells by blocks transcription and damages the deoxyribonucleic acid (DNA) of tumor cells, which is similar to the way radiation kills tumor cells. Traditional chemotherapy and radiotherapy is a routine medical treatment for locally-advanced SCLC, but the combination is always toxic. This trial may help understand if treating patients with lurbinectedin and radiotherapy could cause less side effects.

PRIMARY OBJECTIVE:

To describe the safety in terms of radiation therapy (RT) in combination with lurbinectedin in SCLC patients with Single-lesion progression after first course treatment.

SECONDARY OBJECTIVES:

To evaluate the preliminary efficacy of RT plus lurbinectedin, as assessed by Progression free survival (PFS) and Overall survival (OS).

OUTLINE:

Patients receive 2 cycles of lurbinectedin combined with radiotherapy followed by lurbinectedin alone. Patients receive lurbinectedin intravenously (IV) over 1 hour on day 1 of each cycle. G-CSF（Granulocyte Colony-Stimulating Factor） will be used for prophylaxis.

Inclusion Criteria:

• Has fully understood this study, voluntarily signed a written informed consent form, and is able to comply with the requirements and restrictions listed in the informed consent form;
• Age ≥ 18 years, Male/female participants;
• Has an Eastern Cooperative Oncology Group (ECOG) performance status (PS) of 0 to 2;
• With pathologically confirmed diagnosis of SCLC,with Single-lesion progression after first course treatment;
• Has sufficient bone marrow, liver, kidney, and metabolic function, i.e., the functional levels of organs meet the following requirements:
• Platelets (PLT) ≥ 100×10^9/L;
• Hemoglobin (Hb) ≥ 90 g/L;
• Absolute neutrophil (ANC) ≥ 2.0×10^9/L;
• Regardless of whether liver metastasis is present, alanine aminotransferase (ALT) and aspartate aminotransferase (AST) ≤ 3.0× upper limit of normal (ULN);
• Alkaline phosphatase (ALP) ≤ 5×ULN;
• Total bilirubin (TBIL) ≤ 1.5×ULN, and direct bilirubin ≤ 1.0×ULN;
• Serum creatinine ≤ 1.5×ULN or creatinine clearance rate ≥ 30 mL/min (calculated using the Cockcroft-Gault formula);
• Creatine phosphokinase (CPK) ≤ 2.5×ULN;
• Albumin ≥ 3.0 g/dL.
• A female of childbearing potential (FCBP) must have a negative serum pregnancy test prior to study entry. Woman of childbearing potential (WOCBP) must use adequate contraception during the test drug treatment period and for 6 months after the final dose. Male patients (with partners of WOCBP) must use adequate contraception for the duration of study participation, and 4 months after completion of administration.

Exclusion Criteria:

• With concurrent brain metastasis, a history of spinal cord compression, or meningeal metastasis;

• Patients with obstructive atelectasis, superior vena cava syndrome requiring surgical/ endoscopic/ interventional treatment; suspected or confirmed pulmonary embolism patients; those with uncontrollable large amounts of pleural effusion, ascites, or pericardial effusion;

• Patients known to be allergic to any component of the test drug;

• Pregnancy or breastfeeding or WOCBP who has a positive serum pregnancy test;

• Comorbidities Requirements:

  1. Has unstable angina, myocardial infarction, congestive heart failure (CHF) classified as New York Heart Association (NYHA) II or higher, or other clinically significant cardiovascular diseases currently or within the past year prior to screening;
  2. Patients with uncontrolled hypertension (systolic blood pressure greater than 160 mmHg and/or diastolic blood pressure greater than 100 mmHg), or a history of hypertensive crisis or hypertensive encephalopathy;
  3. Patients with severe arrhythmias requiring medication;
  4. Patients with active infections requiring systemic antibacterial, antifungal, or antiviral treatment within 2 weeks prior to administration;
  5. Patients with evidence of bleeding tendencies or coagulation disorders;
  6. Patients with other significant diseases judged unsuitable for entry by the investigator.

Individual participant data (IPD) will not be shared