Trilaciclib (G1T28) in Patients With Previously Treated Extensive Stage SCLC Receiving Topotecan Chemotherapy

Key Inclusion Criteria: * Male or female subjects aged ≥18 years * Confirmed diagnosis of SCLC by histology or cytology, preferably including the presence of neuroendocrine features by immunohistochemistry * Progression during or after prior first- or second-line chemotherapy and eligible to receive topotecan therapy * At least 1 target lesion that is measurable by RECIST, Version 1.1 * Eastern Cooperative Oncology Group (ECOG) performance status of 0 - 2 * Adequate organ function Key Exclusion Criteria: * Presence of brain metastases requiring immediate treatment with radiation therapy or steroids. * Uncontrolled ischemic heart disease or uncontrolled symptomatic congestive heart failure * Known history of stroke or cerebrovascular accident within 6 months prior to enrollment * Other uncontrolled serious chronic disease or conditions that in the investigator's opinion could affect compliance or follow-up in the protocol * Concurrent radiotherapy to any site or radiotherapy within 2 weeks prior to enrollment or previous radiotherapy to the target lesion sites * Receipt of any systemic chemotherapy regimen within 4 weeks prior to enrollment or a noncytotoxic investigational medication within 2 weeks prior to enrollment * History of topotecan treatment for SCLC