Trilaciclib vs Placebo in Patients With Extensive Stage Small Cell Lung Cancer (ES-SCLC) Receiving Topotecan

This study tests whether a drug called trilaciclib can protect the bone marrow of people with advanced small cell lung cancer who are receiving a chemotherapy called topotecan. Trilaciclib works by temporarily putting bone marrow cells to sleep during chemotherapy, which may reduce harmful side effects like low blood cell counts. **You may be eligible if...** - You have been diagnosed with extensive-stage small cell lung cancer (a type of lung cancer that has spread) - Your cancer has progressed during or after one or two previous chemotherapy regimens - Your first chemotherapy included a platinum-based drug - Your cancer has at least one measurable spot on scans **You may NOT be eligible if...** - You have previously received topotecan or trilaciclib - You had chemotherapy, immunotherapy, or other cancer treatment within the past 3 weeks - You have brain metastases that need immediate radiation or steroids - You had radiation therapy within the past 2 weeks - You have a history of lung inflammation (ILD/pneumonitis) - You have another active cancer within the past 2 years Talk to your doctor to see if this trial is right for you.