An Open-Label, Phase 1b Study to Evaluate Safety, Tolerability & Preliminary Activity of the CTPS1 Inhibitor STP938 in Adult Subjects With High Risk Essential Thrombocythaemia Who Are Resistant to or Intolerant of Hydroxycarbamide Therapy
The goal of this clinical trial is to learn if the drug STP938 works to treat adults with high risk essential thrombocythaemia (ET) who are resistant to, or intolerant of, hydroxycarbamide (also known as hydroxyurea) therapy. The trial will also learn about the safety of STP938. The main questions the trial aims to answer are: * Does STP938 control platelet counts * Does STP938 control platelet counts without inducing unwanted side effects Participants will: * Take STP938 every day for up to 12 months. * Visit the clinic once every week for the first month, then every 2 weeks for checkups and tests. * Complete a questionnaire about symptoms once a month.
• Adults aged 18 years or older
• A confirmed diagnosis of ET according to World Health Organisation (WHO) or British Society for Haematology (BSH) criteria.
• Meeting criteria for high risk ET.
• Raised platelet count (\>600 x109/L) requiring cytoreductive therapy.
• Neutrophil count \>1.0 x109/L.
• Either intolerant of or resistant to hydroxycarbamide having met any one of the criteria at any point in their disease whilst receiving hydroxycarbamide.
• Adequate hepatic function.
• Adequate blood coagulation parameters.
• Eastern Cooperative Oncology Group (ECOG) status of 0-2.