A Phase 1 Study to Assess STP938 as a Monotherapy in Adults With High Risk Essential Thrombocythaemia
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
Step Pharma, SAS
20 participants
Jun 18, 2025
INTERVENTIONAL
Conditions
Summary
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.
Eligibility
Inclusion Criteria9
- 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.
Exclusion Criteria11
- Subjects currently or recently receiving cytoreductive therapy for the treatment of essential thrombocythaemia (wash out periods apply).
- Subjects who have received any investigational agents for the treatment of essential thrombocythaemia within 4 weeks before enrolment or less than 5 half-lives since completion of prior therapy, whichever is shorter.
- Proven or suspected transformation to polycythaemia vera, myelofibrosis, myelodysplasia, acute myeloid leukaemia or another myeloid neoplasm.
- Known malabsorption syndrome or other condition that may impair absorption of study medication (e.g. gastrectomy).
- Previous splenectomy.
- Any uncontrolled intercurrent illness.
- Immunocompromised subjects with increased risk of opportunistic infections.
- Known active or chronic hepatitis B or active hepatitis C virus (HCV) infection.
- Pregnant females, breastfeeding females, and women of child bearing age or males not willing to comply with contraceptive requirements.
- Known hypersensitivity to any of the excipients used in the formulation of the study drug.
- Corrected QT interval >470 msec based on averaged triplicate electrocardiogram (ECG) readings at the Screening Visit using the QT interval corrected for heart rate using Fridericia's method (QTcF).
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Interventions
At enrolment all patients will be assigned to a single dose level of STP938 for 4 weeks. After 4 weeks the dose level may be adjusted as needed by the Investigator.
Locations(13)
View Full Details on ClinicalTrials.gov
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NCT06786234