Atezolizumab and Rechallenge Chemotherapy in Relapsed Patients With Extensive-stage Small Cell Lung Cancer (ES-SCLC).

The goal of this clinical trial is to learn if a combination of atezolizumab and standard chemotherapy works to treat sensitive Extensive-stage Small Cell Lung Cancer, progressing after first-line of treatment. The main questions it aims to answer are: * Does combination of atezolizumab and standard chemotherapy increase overall survival? * What medical problems do participants have when taking combination of atezolizumab and standard chemotherapy? Participants will: * take atezolizumab and standard chemotherapy every 3 weeks for 4 cycles and than atezolizumab every 3 weeks up to 18 cycles. * visit the clinic once every 3 weeks for checkups and tests * perform Radiological assessments after 6 weeks and then every 12 weeks to determine response to treatment.