• Diagnosis of small-cell lung cancer (SCLC) (according to WHO classification 2015) confirmed at pathology (histology or cytology).

• Male or female and ≥ 18 years of age.

• Life expectancy ≥ 12 weeks.

• Disease progression at least 60 days after the completion of first-line chemotherapy consisting of at least 4 cycles of platinum-etoposide plus either atezolizumab or durvalumab and have not received any other treatment (except for immunotherapy as maintenance treatment); the 60 day-interval is calculated from the date of the last chemotherapy administration to the date of the first radiologically documented progressive disease.

• No previous radiotherapy on the only one site disease progression, unless that site had subsequent evidence of progressive disease.

• Eastern Cooperative Oncology Group performance status (ECOG PS) ≤2.

• Patients with treated brain metastases (or untreated but asymptomatic) and off steroids or on a stable dose of steroids (≤10 mg of prednisone-equivalent) are also eligible. Radiotherapy must have been completed a minimum of 14 days prior to registration, and patients must have recovered from AEs related to radiotherapy to \< grade 1 (except alopecia)

• For Females: must be postmenopausal (defined as occurring 12 months after last menstrual period) before the screening visit, or are surgically sterile. If they are of childbearing potential, a negative serum pregnancy test prior to study entry has to be documented; furthermore, they agree to practice 2 effective methods of contraception, at the same time, from the time of signing the informed consent form (ICF) through 5 months after the last dose of study drug,or agree to practice true abstinence, when this is in line with the preferred and usual lifestyle of the subject.

• For Males: even if surgically sterilized (i.e., post-vasectomy status) agree to practice effective barrier contraception during the entire study treatment period and through 6 months after the last dose of study drug, or practice true abstinence, when this is in line with the preferred and usual lifestyle of the subject.

⁃ Normal baseline laboratory values as specified below:

∙ Absolute neutrophil count (ANC) ≥1500/mm3

‣ Platelet count ≥ 100 x 109/L (≥100,000/μL) without transfusion

‣ Hemoglobin ≥ 90 g/L (≥ 9 g/dL); patients may be transfused to meet this criterion.

‣ Total bilirubin \< 1.5x the institutional upper limit of normal (ULN)

‣ Serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \< 2.5x the institutional ULN (\< 5x if liver function test elevations are due to liver metastases)

‣ Creatinine \< 1.5x institutional ULN or estimated creatinine clearance using the Cockcroft-Gault formula ≥ 30 mL/minute for patients with creatinine levels above institutional limits

‣ For patients not receiving therapeutic anticoagulation: INR and aPTT ≤ 1.5 x ULN

‣ Negative HIV test at screening {with the following exception: patients with a positive HIV test at screening are eligible provided they are stable on anti-retroviral therapy, have a CD4 count ≥ 200/μL, and have an undetectable viral load}

‣ Negative hepatitis B surface antigen (HBsAg) test at screening

‣ Positive hepatitis B surface antibody (HBsAb) test at screening, or negative HBsAb at screening accompanied by either of the following:

⁃ Negative total hepatitis B core antibody (HBcAb)

• Positive total HBcAb test followed by a negative (per local laboratory definition) hepatitis B virus (HBV) DNA testNegative hepatitis C virus (HCV) antibody test at screening, or positive HCV antibody test followed by a negative HCV RNA test at screening The HCV RNA test must be performed for patients who have a positive HCV antibody test.

⁃ Stable medical condition, including the absence of acute exacerbations of chronic illnesses, serious infections, or major surgery within 4 weeks before registration, and otherwise noted in other inclusion/exclusion criteria.

⁃ Recovered (i.e., ≤ grade 1 toxicity) from effects of prior anticancer therapy, except alopecia.

⁃ Prior radiotherapy is allowed provided that it has been completed more than 2 weeks before starting protocol treatment and patients have recovered from AEs related to radiotherapy to \< grade 1

⁃ Ability to comply with protocol requirements.

⁃ The patient or the patient's legal representative has to be able to provide written informed consent. Voluntary written consent must be given before performance of any study-related procedure not part of standard medical care, with the understanding that consent may be withdrawn by the patient at any time without prejudice to future medical care.