This clinical trial is focused on studying the treatment of Small Cell Lung Cancer (SCLC), a type of lung cancer that often requires additional treatment after the first round of therapy. The study will use a medication called AL8326, which is a type of drug known as a receptor kinase inhibitor. This medication is taken in the form of a tablet. The purpose of the study is to evaluate the safety and effectiveness of AL8326 for patients who need further treatment for SCLC, especially those who have controlled brain metastasis, meaning the cancer has spread to the brain but is not actively causing bleeding.

Participants in the study will receive AL8326 as a second-line treatment, which means it is given after the initial treatment has been completed. The study will explore different doses of the medication to find the best balance between effectiveness and safety. Some participants may receive a placebo, which is a substance with no active medication, to compare the effects. The study will last for a period of up to 12 months, during which the health and response of the participants will be closely monitored.

The trial aims to determine the optimal dose of AL8326 that provides the best results for patients with SCLC. This includes looking at how well the cancer responds to the treatment and how long the benefits last. The study will also gather information on how the body processes the medication and any potential side effects. This research is important for improving treatment options for patients with Small Cell Lung Cancer who need further therapy after their initial treatment.