A Clinical Trial of Bomedemstat in Participants With Polycythemia Vera (MK-3543-025)

A Phase 2/3, Randomized, Open-label, Active-comparator-controlled, Parallel-group, Multicenter Study to Evaluate the Safety and Efficacy of Bomedemstat (MK-3543) Versus Best Available Therapy in Participants With Polycythemia Vera Who Have an Inadequate Response to or Are Intolerant to Hydroxyurea

Researchers are looking for new ways to treat polycythemia vera (PV). People with PV may receive treatment to lower the number of red blood cells in the blood, but the usual treatments may not work for everyone. Researchers want to learn if a trial medicine called bomedemstat, also called MK-3543, can treat PV. In this study, researchers will compare bomedemstat to 2 usual treatments for PV.

The goal of this study is to learn if more participants who take bomedemstat reach healthy blood cell counts and avoid major health problems from PV, compared to those who receive a usual treatment.

Study Overview

• Status: Not yet recruiting
• Conditions: Polycythemia Vera
• Intervention / Treatment: Drug: Bomedemstat; Drug: Ruxolitinib; Drug: Ropeginterferon alfa-2b

• Study Type: Interventional
• Enrollment (Estimated): 380
• Phase: Phase 2; Phase 3

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

The main inclusion criteria include but are not limited to the following:

• Has confirmed local diagnosis of polycythemia vera (PV) per World Health Organization (WHO) diagnostic criteria for PV
• Must have discontinued prior cytoreductive therapy for condition under study for protocol specified duration
• Has failed at least one prior line of cytoreductive therapy to lower hematocrit
• Has a history of inadequate response, resistance to, or intolerant to hydroxyurea (HU) per protocol specified criteria
• Has no evidence of splenomegaly and no symptoms attributable to splenomegaly, including early satiety, left upper quadrant discomfort, or splenic pain
• Has locally assessed bone marrow (BM) fibrosis score of Grade 0 or Grade 1 as per modified version of the European Consensus Criteria for Grading Myelofibrosis
• Human Immunodeficiency Virus (HIV)-infected participants have well controlled HIV on antiretroviral therapy (ART)
• Participants who are Hepatitis B surface antigen (HBsAg) positive are eligible if they have received Hepatitis B Virus (HBV) antiviral therapy for at least 4 weeks and have undetectable HBV viral load
• Participants with history of Hepatitis C Virus (HCV) infection are eligible if HCV viral load is undetectable
• Participants must be able to swallow oral medication and follow instructions for at home dosing of bomedemstat

Exclusion Criteria:

The main exclusion criteria include but are not limited to the following:

• Has history of any illness/impairment of gastrointestinal (GI) function that might interfere with drug absorption
• Has evidence at the time of screening of increased risk of bleeding
• Has history of malignancy, unless potentially curative treatment has been completed with no evidence of malignancy for 2 years
• HIV-infected participants with a history of Kaposi's sarcoma and/or Multicentric Castleman's Disease
• Is currently receiving anticancer therapy
• Has an active infection requiring systemic therapy
• Has had major surgical procedure ≤4 weeks before first dose of study intervention or has not recovered from side effects of major surgical procedure

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Bomedemstat; Participants will receive bomedemstat daily for up to approximately 52 weeks. Per protocol, dosage may be adjusted within specified time parameters for each participant to achieve and maintain protocol-specified platelet and hematocrit target ranges. Eligible participants who do not discontinue study treatment at Week 52, may continue to receive study treatment.	Drug: Bomedemstat; Oral Capsule; Other Names: IMG-7289; MK-3543; Bomedemstat tosylate
Active Comparator: Best Available Therapy (BAT); Participants will receive either ropeinterferon alfa-2b or ruxolitinib as determined by investigator. All participants will be treated per respective approved product labels for up to approximately 52 weeks.	Drug: Ruxolitinib; Oral Tablet; Drug: Ropeginterferon alfa-2b; Subcutaneous Solution

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Clinicohematologic Response (CHR) Rate	CHR Rate is defined as all of the following: (i) a confirmed hematologic remission sustained for at least 12 consecutive weeks by Week 40 through Week 52, (ii) and absence of any of the following as assessed by the adjudication committee Week 52: thrombotic event; major hemorrhagic events; disease progression to myelofibrosis (MF) or myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML). CHR will begin on the date of the first confirmed assessment achieving CHR criteria and will end on the earliest date of the following: 1) day of the first confirmed assessment not achieving CHR criteria, 2) date of first major hemorrhagic event or thrombotic event as assessed by the adjudication committee, or 3) disease progression as assessed by the adjudication committee. The CHR rate will be presented.	Up to approximately Week 52

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Clinicohematologic Response Sustained for a 24-Week Time Period (CHR24)	CHR24 is defined as all of the following: (i) a confirmed hematologic remission sustained for at least 24 consecutive weeks by Week 52, (ii) and absence of any of the following as assessed by the adjudication committee Week 52: thrombotic event; major hemorrhagic events; disease progression to MF or MDS/AML. CHR24 will begin on the date of the first confirmed assessment achieving CHR24 criteria and will end on the earliest date of the following: 1) day of the first confirmed assessment not achieving CHR24 criteria, 2) date of first major hemorrhagic event or thrombotic event as assessed by the adjudication committee, or 3) disease progression as assessed by the adjudication committee. The CHR24 will be presented.	Up to approximately Week 52
Number of Participants Who Experience an Adverse Event (AE)	An AE is any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. The number of participants who experience AE will be reported.	Up to approximately Week 52
Number of Participants Who Discontinue Study Treatment Due to an AE	An AE is any untoward medical occurrence in a participant, temporally associated with the use of study treatment, whether or not considered related to the study treatment. The number of participants who discontinue study treatment due to an AE will be reported.	Up to approximately Week 52
Duration of Clinicohematologic Response Sustained for a 24-Week Time Period (DOCHR24)	For participants who show CHR24, DOCHR24 is defined as the time from the first confirmed hematologic remission to first documented evidence of: 1) confirmed platelet increase, confirmed WBC increase, or a required phlebotomy (defined as a confirmed HCT reduction) after latest confirmed hematologic remission date, 2) thrombotic event as assessed by the adjudication committee, 3) major hemorrhagic event as assessed by the adjudication committee, or 4) disease progression to MF or MDS/AML as assessed by the adjudication committee.	Up to approximately Week 52
Duration of Clinicohematologic Response (DOCHR)	For participants who show CHR, DOCHR is defined as the time from the first confirmed hematologic remission to first documented evidence of: 1) confirmed platelet increase, confirmed WBC increase, or a required phlebotomy (defined as a confirmed HCT reduction) after latest confirmed hematologic remission date, 2) thrombotic event as assessed by the adjudication committee, 3) major hemorrhagic event as assessed by the adjudication committee, or 4) disease progression to MF or MDS/AML as assessed by the adjudication committee.	Up to approximately Week 52
Duration of Hematologic Remission (DOHR)	For participants who show confirmed hematologic remission, DOHR is defined as the time from the first hematologic remission until loss of hematologic remission.	Up to approximately Week 52
Number of Participants Who Experience Phlebotomies	Per protocol, a required phlebotomy is defined as confirmed hematocrit (HCT) ≥45% with a ≥3% increase from baseline HCT or confirmed HCT ≥48%. The number of participants who experienced phlebotomies will be presented.	Up to approximately Week 52
Disease Progression Rate	Disease progression is defined as the transformation to post polycythemia vera myelofibrosis, myelodysplastic syndrome, or acute myeloid leukemia as assessed by the adjudication committee. The disease progression rate will be presented.	Up to approximately Week 52
Number of Participants Who Experience Thrombotic Events	Thrombotic events are defined as new or recurrent acute myocardial infarction, unstable angina, stroke, transient ischemic attack (TIA), deep venous thrombosis (DVT), pulmonary embolism (PE), thrombotic digital ischemia, other thrombotic events such as peripheral limb ischemia or Budd-Chiari syndrome assessed to be due to underlying polycythemia vera (PV), and other vascular occlusive events such as symptoms of cardiac, abdominal, or peripheral limb ischemia supported by objective evidence of vessel disease and/or ischemia. The number of participants who experience thrombotic events will be presented.	Up to approximately Week 52
Number of Participants Who Experience Major Hemorrhagic Events	Major hemorrhagic events include but are not limited to fatal bleeding, symptomatic bleeding in a critical area or organ (including intracranial, intraspinal, intraocular, retroperitoneal, intra-articular, pericardial, or intramuscular with compartment syndrome), or bleeding causing a decrease in hemoglobin of 2 g/dL or more or leading to transfusion of 2 or more units of whole blood or red cells, and clinically relevant non-major bleeding events leading to hospitalization or increased level of care or clinically important bleeding prompting a face-to-face medical evaluation.	Up to approximately Week 52
Change From Baseline in Myelofibrosis Symptom Assessment Form version 4.0 (MFSAF v4) Total Symptom Score	The MFSAF v4.0 is a 7-item participant-reported symptom assessment that asks respondents to report symptom severity at its worst for each of the 7 items on a 0 (Absent) to 10 (Worst Imaginable) numeric rating scale. The MFSAF v4.0 7-day recall format is used. Individual symptoms are assessed on an 11-point numeric rating scale with a total symptom score range of 0 (absent) to 70 (worst imaginable). The change from baseline in MFSAF total score for all symptoms will be presented	Up to approximately Week 52
Change From Baseline in Patient-Reported Outcomes Measurement Information System (PROMIS) Fatigue Short Form (SF) 7a Total Fatigue Score	The PROMIS Fatigue SF is a 7-item participant-reported assessment that measures both the experience of fatigue and the interference of fatigue on daily activities over the past week. Response options are on a 5-point Likert scale, ranging from 1 (never) to 5 (always). A total score is obtained by summing the responses to the seven items [range 7 (never) to 35 (always)] and converting to a standardized T-score. The change from baseline in PROMIS Fatigue SF-7a Total Fatigue Score will be presented.	Up to approximately Week 52

Collaborators and Investigators

• Sponsor: Merck Sharp & Dohme LLC
• Investigators: Study Director: Medical Director, Merck Sharp & Dohme LLC

Study record dates

Study Major Dates

• Study Start (Estimated): September 21, 2026
• Primary Completion (Estimated): June 25, 2032
• Study Completion (Estimated): November 30, 2032

Study Registration Dates

• First Submitted: July 20, 2026
• First Submitted That Met QC Criteria: July 20, 2026
• First Posted (Actual): July 23, 2026

Study Record Updates

• Last Update Posted (Actual): July 23, 2026
• Last Update Submitted That Met QC Criteria: July 20, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Neoplasms by Site; Neoplasms; Hematologic Diseases; Bone Marrow Diseases; Myeloproliferative Disorders; Bone Marrow Neoplasms; Hematologic Neoplasms; Hemic and Lymphatic Diseases; Polycythemia Vera; ruxolitinib; bomedemstat
• Other Study ID Numbers: 3543-025; MK-3543-025 (Other Identifier: MSD)

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No