Phase 1b/2a Safety and Pharmacokinetic Study of G1T28 in Patients With Previously Treated Extensive Stage Small Cell Lung Cancer (SCLC) Receiving Topotecan Chemotherapy

This is a study to investigate the potential clinical benefit of trilaciclib (G1T28) in
preserving the bone marrow and the immune system, and enhancing chemotherapy antitumor
efficacy when administered prior to topotecan in patients previously treated for
extensive-stage SCLC.

The study consists of 2 parts: a limited open-label, dose-finding portion (Part 1), and a
randomized double-blind portion (Part 2). Both parts include 3 study phases: Screening Phase,
Treatment Phase, and Survival Follow-up Phase. The Treatment Phase begins on the day of first
dose with study treatment and completes at the Post-Treatment Visit. The open-label portion
enrolled 32 patients and the randomized portion will enroll approximately 90 patients.