The study will include 3 study phases: Screening Phase, Treatment Phase, and Survival Follow-up Phase. Patients randomized in this study will receive trilaciclib/placebo + topotecan 1.5 mg/m2 until disease progression, unacceptable toxicity, withdrawal of consent, Investigator decision to discontinue treatment, or the end of the trial, whichever comes first.~Trilaciclib was approved by the United States (US) Food and Drug Administration (FDA) as a treatment to decrease the incidence of chemotherapy-induced myelosuppression in adult patients when administered prior to a platinum/etoposide-containing regimen or topotecan-containing regimen for ES-SCLC. As a post-marketing requirement, the FDA asked the Sponsor to conduct a study in patients with ES-SCLC undergoing chemotherapy to evaluate survival and disease progression following trilaciclib administration in patients treated with a platinum/etoposide-containing regimen or topotecan-containing regimen with at least 2 years of follow-up. This study is designed to fulfill this requirement.
This is a multicenter, randomized, double-blind, placebo-controlled study to assess whether trilaciclib administered prior to topotecan is non-inferior to placebo administered prior to topotecan with regard to overall survival.