A Phase 1 Study to Assess STP938 as a Monotherapy in Adults With High Risk Essential Thrombocythaemia

NCT06786234 | Recruiting Phase 1

• 1 other identifier: STP938-301
• Study Type: interventional
• Target: 20
• Locations: 2 countries
• Sites: 13

Brief 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.

Conditions

Essential Thrombocythaemia

Keywords

Essential Thrombocythemia; High risk; Resistant to or Intolerant of Hydroxycarbamide Therapy; Resistant to or Intolerant of Hydroxyurea Therapy; Oral therapy

Outcome Measures

Primary Outcomes (2)

• Clinical Efficacy

  Complete and partial response rates per European LeukemiaNet criteria

  Through study completion, an average of 12 months

• Safety and Tolerability

  Toxicity profile based on National Cancer Institute Common Terminology Criteria for Adverse Events

  Through study completion, an average of 12 months

Secondary Outcomes (2)

• Durability of Response to STP938

  Through study completion, an average of 12 months

• Impact of STP938 on Disease-Related Complications

  Through study completion, an average of 12 months

Other Outcomes (4)

• Patient Reported Outcomes and Symptom Burden

  Through study completion, an average of 12 months

• Molecular Response

  Through study completion, an average of 12 months

• Bone Marrow Histology

  Screening and Cycle 12 (each cycle is 28 days)

Study Arms (1)

Phase 1b

EXPERIMENTAL

Up to 5 dose levels with STP938 administered as oral therapy

Drug: STP938

Interventions

STP938 DRUG

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.

Phase 1b

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• 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).

Sponsors & Collaborators

• Step Pharma, SAS: lead

Study Sites (13)

CHU Brest

Brest, France

RECRUITING

Institut Paoli-Calmettes

Marseille, France

RECRUITING

CHU Nantes

Nantes, France

RECRUITING

CHU Nice

Nice, France

RECRUITING

CHU Nîmes

Nîmes, France

RECRUITING

Hôpital Saint-Louis

Paris, France

RECRUITING

Gustave Roussy

Villejuif, France

RECRUITING

Royal Hallamshire Hospital

Sheffield, South Yorkshire, S10 2JF, United Kingdom

NOT YET RECRUITING

University Hospital of Wales

Cardiff, United Kingdom

RECRUITING

Imperial College London / Hammersmith Hospital

London, United Kingdom

RECRUITING

Sarah Cannon Research Institute

London, United Kingdom

RECRUITING

Cancer and Haematology Centre, Churchill Hospital

Oxford, OX3 7LE, United Kingdom

RECRUITING

University of Southampton Hospital

Southampton, United Kingdom

RECRUITING

MeSH Terms

Conditions

Thrombocythemia, Essential

Condition Hierarchy (Ancestors)

Blood Coagulation Disorders; Hematologic Diseases; Hemic and Lymphatic Diseases; Thrombocytosis; Blood Platelet Disorders; Myeloproliferative Disorders; Bone Marrow Diseases; Hemorrhagic Disorders

Study Officials

• Maureen Higgins

  Step Pharma

  STUDY DIRECTOR

Central Study Contacts

Carol M MacLean, PhD

CONTACT

+33 1 86 26 43 56; STP938-301@step-ph.com

Maureen Higgins, PhD, MBA

CONTACT

+33 1 86 26 43 56; STP938-301@step-ph.com

Study Design

• Study Type: interventional
• Phase: phase 1
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: January 8, 2025
• First Posted: January 22, 2025
• Study Start: June 18, 2025
• Primary Completion (Estimated): May 31, 2026
• Study Completion (Estimated): December 31, 2027
• Last Updated: January 28, 2026

Record last verified: 2026-01

Data Sharing

• IPD Sharing: Will not share

Locations

FR (7); GB (6)