Phase Ib/II Study to Evaluate the Safety, Efficacy, and Pharmacokinetics of YL201 in Combination with Atezolizumab in Patients with Advanced Solid Tumors

The primary objectives of this study involve evaluating the safety and determining the maximum tolerated dose of YL201 in combination with atezolizumab in patients with advanced solid tumors. Additionally, the study aims to assess the anti-tumor activity of this combination therapy. 4, 5

Secondary objectives include the characterization of pharmacokinetics and the assessment of immunogenicity through the incidence of anti-YL201 antibodies. Further evaluations will focus on clinical efficacy parameters, including objective response rate, progression-free survival, duration of response, and overall survival, while also monitoring safety and tolerability through the observation of adverse events and laboratory abnormalities. 6

The study includes 110 patients with extensively metastatic small cell lung cancer. The population consists of both male and female individuals within specific age ranges. Participants must have a pathologically confirmed diagnosis and must not have received any prior systemic anti-cancer treatment. Eligible subjects are required to have an Eastern Cooperative Oncology Group performance status of 0 or 1, along with at least one evaluable tumor lesion according to RECIST version 1.1. Additional requirements include adequate organ function, adequate bone marrow function, and a life expectancy of at least 3 months.

This is a Phase Ib/II, multicenter, open-label study designed to evaluate the safety, efficacy, and pharmacokinetics of YL201 in combination with atezolizumab in patients with advanced solid tumors. The research is divided into two parts. Part 1 focuses on assessing safety and determining the maximum tolerated dose. Part 2 aims to evaluate anti-tumor activity. Primary endpoints for Part 1 include adverse events, laboratory abnormalities, and dose-limiting toxicities. Part 2 primary endpoints consist of the objective response rate and progression-free survival, both assessed according to RECIST version 1.1. Secondary endpoints include overall survival and the duration of response. The study involves a screening process to confirm eligibility based on criteria such as ECOG performance status, pathologically confirmed diagnosis, and adequate organ and bone marrow function.

The experimental treatment consists of atezolizumab, provided as a 200 mg concentrate for solution for infusion. This substance is administered via intravenous use.

The experimental treatment also includes YL201, which is administered as an infusion through intravenous infusion.

The assessment of efficacy in this study focuses on the anti-tumor activity of YL201 in combination with atezolizumab in patients with advanced solid tumors. In Part 2, the primary efficacy endpoints include the objective response rate (ORR) and progression-free survival (PFS), both of which are evaluated according to RECIST version 1.1.

Secondary efficacy evaluations include:

• Duration of response (DOR) as assessed by RECIST version 1.1.
• Overall survival (OS).
• The objective response rate (ORR) as a secondary endpoint in Part 1.