This study explores a new drug, CGT9486 or bezuclastinib, for people with a serious condition called Advanced Systemic Mastocytosis (AdvSM). This means there are too many mast cells in the body, which can cause various health problems. The study is open-label, meaning both the doctors and patients know the treatment being given.

To be part of the main study, individuals must have certain types of AdvSM, like Aggressive Systemic Mastocytosis (ASM), Systemic Mastocytosis with Associated Hematologic Neoplasm (SM-AHN), or Mast Cell Leukemia (MCL). They need to have certain lab results and meet other health criteria. The study includes two parts, with a special focus on people whose conditions are worsening or who are at high risk.

• The study lasts for several weeks and involves regular health checks.
• Participants may receive some form of compensation.
• Risks include potential side effects from the drug and frequent doctor visits.