A Phase 3 interventional study of Bomedemstat in Thrombocythemia, Essential, Primary Myelofibrosis and Myelofibrosis, sponsored by Merck Sharp & Dohme LLC. Recruiting at 21 sites in 6 countries. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-11-10.
Sponsored by Merck Sharp & Dohme LLC (part of Merck & Co., Inc) · Phase 3, Interventional, and Treatment
The primary purpose of the study is to transition participants into an extension study to collect long-term safety and efficacy data. The study will include participants who are safely tolerating bomedemstat, receiving clinical benefit from its use in estimation of the investigator, and have shown the following criteria:
No hypothesis testing will be conducted in this study.
229 studies on the registry are indexed under Thrombocythemia, Essential; 38 are open to participants now.
This study's planned enrollment of 400 is above the median of 52 across 168 interventional studies indexed under Thrombocythemia, Essential.
Browse Thrombocythemia, Essential studies →Merck Sharp & Dohme LLC is the lead sponsor of 2,166 studies on the registry; 132 are open to participants now.
Of its 501 completed or terminated interventional studies of FDA-regulated products, 370 (74%) have results posted.
Counted across the registry records on this site, refreshed daily.
The criteria were revised on the registry on Nov 10, 2026. See what changed
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Investigational drug or device
A drug or device being studied in a clinical trial.
It may be new, or already approved and being studied for another use, dose or form. Criteria often leave out people who took part in another study of one within a recent period, commonly 30 days or five half-lives.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Participants will receive oral capsules of bomedemstat once daily for up to 10 years, with the starting dose as the same dose that the participant was on at the time of transition from the feeder study.
Drug: Bomedemstat
10, 15, 20, and 50 mg oral capsules
Also known as: MK-3543, IMG-7289
Percentage of participants with one or more adverse events (AEs)
An AE is any undesirable physical, psychological or behavioral effect experienced by a patient during participation in an investigational study, in conjunction with the use of the drug or biologic, whether or not product-related. This includes any untoward signs or symptoms experienced by the patient from the time of first dose with bomedemstat under this protocol until completion of the study. The percentage of participants with AEs will be presented.
Time frame: Up to ~10 years
Percentage of participants who discontinued study treatment due to an AE
An AE is any undesirable physical, psychological or behavioral effect experienced by a patient during participation in an investigational study, in conjunction with the use of the drug or biologic, whether or not product-related. This includes any untoward signs or symptoms experienced by the patient from the time of first dose with bomedemstat under this protocol until completion of the study. The percentage of participants who discontinued study treatment due to an AE will be presented.
Time frame: Up to ~10 years
For participants with ET: Duration of durable clinicohematologic response
For participants who demonstrate durable clinicohematologic response (DCHR) in their feeder study, duration of durable clinicohematologic response (DODCHR) is defined as the time from the first documented evidence of confirmed reduction of platelet and white blood cell (WBC) counts until confirmed increase of platelet and WBC counts to above acceptable threshold, thrombotic or major hemorrhagic events, or disease progression to myelofibrosis (MF), myelodysplastic syndrome (MDS), or acute myeloid leukemia (AML). DODCHR will be reported.
Time frame: Up to ~10 years
For participants with ET or PV: Duration of clinicohematologic response
For participants who showed clinicohematologic response in their feeder study, duration of clinicohematologic response is defined as the time from the first documented evidence of confirmed reduction of platelet and WBC count until confirmed increase of platelet and WBC counts to above acceptable threshold, thrombotic or major hemorrhagic events or disease progression to MF, MDS, or AML, or phlebotomy (PV participants only). The duration of clinicohematologic response will be reported.
Time frame: Up to ~10 years
For participants with ET or PV: Duration of hematologic response
For participants who showed confirmed hematologic response in their feeder study, duration of hematologic response is defined as the time from the first documented evidence of confirmed reduction of platelet and WBC count until confirmed increase of platelet and WBC counts to above acceptable threshold, or phlebotomy (PV participants only). The duration of hematologic response will be reported.
Time frame: Up to ~10 years
For participants with ET or PV: Percentage of participants with transformation to MF or MDS/AML
Disease Progression is defined as the transformation to post-ET myelofibrosis (ET participants only), post-PV myelofibrosis (PV participants only), spleen volume increase ≥25% (MF participants only), myelodysplastic syndrome, or acute myeloid leukemia as assessed by the investigator. The percentage of participants with transformation to MF or MDS/AML will be reported.
Time frame: Up to ~10 years
For participants with MF: Percentage of participants with worsening of splenomegaly or transformation to MDS/AML
Spleen volume will be assessed by magnetic resonance imaging (MRI) (or computed tomography \[CT\] where applicable) at pre-specified timepoints. The percentage of participants with worsening of splenomegaly or transformation to MDS/AML will be reported.
Time frame: Up to ~10 years
For participants with MF, ET, or PV: Percentage of participants with 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 that are assessed to be due to underlying PV; 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 percentage of participants with thrombotic events will be presented.
Time frame: Up to ~10 years
For participants with MF, ET, or PV: Percentage of participants with major hemorrhagic events
Hemorrhagic events are defined as: Major Bleeding (MB) Events such as fatal bleeding, and/or symptomatic bleeding in a critical area or organ such as intracranial, intraspinal, intraocular, retroperitoneal, intra-articular or pericardial, or intramuscular with compartment syndrome, and/or bleeding causing a fall in hemoglobin level of 2 g/dL or more, or leading to transfusion of 2 or more units of whole blood or red cells; Clinically Relevant Non-Major Bleeding (CRNMB) Events Leading to hospitalization or increased level of care or clinically important, prompting a face-to-face medical evaluation. The percentage of participants with major hemorrhagic events will be presented.
Time frame: Up to ~10 years
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Plan to share: Yes — https://trialstransparency.msdclinicaltrials.com/pdf/ProcedureAccessClinicalTrialData.pdf
Data sharing details ↗ · externaldatasharing-msd.com
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Bomedemstat