This clinical trial is focused on studying a condition known as Systemic Mastocytosis, specifically its nonadvanced forms, which include Indolent Systemic Mastocytosis and Smoldering Systemic Mastocytosis. These are conditions where certain immune cells, called mast cells, build up in the body and can cause various symptoms. The study is testing a treatment called CGT9486, also known as bezuclastinib, which is a type of medication that targets specific proteins involved in the disease process. This medication is taken orally in the form of a tablet.

The purpose of the study is to evaluate the safety and effectiveness of CGT9486 compared to a placebo in patients with nonadvanced systemic mastocytosis. The study is divided into three parts. In the first part, the goal is to determine the best dose of bezuclastinib for patients. The second part aims to assess how well the medication works at the chosen dose compared to a placebo. The third part focuses on understanding the safety and how well patients tolerate the medication.

Participants in the study will take the medication or placebo for a period of time, and their health will be monitored to see how they respond to the treatment. The study will look at changes in symptoms and any side effects that may occur. The overall duration of the study is planned to last until 2026, with the aim of gathering comprehensive data on the treatment’s impact on the condition.