Extension Study of Bomedemstat (IMG-7289/MK-3543) in Participants With Myeloproliferative Neoplasms (IMG-7289-CTP-202/MK-3543-005)

Study Overview
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Brief Summary
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This is a multi-center, open-label extension study to assess the long-term safety and efficacy of bomedemstat (MK-3543, formerly called IMG-7289) administered orally once daily in participants with an MPN who participated in a prior bomedemstat study such as, but not limited to, IMG-7289-CTP-102 and IMG-7289-CTP-201 (referred to hereafter as 'feeder studies').

Official Title
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A Multi-Center, Open Label, Extension Study Evaluating the Safety and Efficacy of Bomedemstat for the Treatment of Patients With Myeloproliferative Neoplasms (MPNs) Enrolled in a Prior Bomedemstat Clinical Study

Conditions
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Thrombocythemia, Essential, Primary Myelofibrosis

Intervention / Treatment
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* Drug: Bomedemstat


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Completed at least one Treatment Period (TP) in a prior bomedemstat MPN protocol (such as, but not limited to, IMG-7289-CTP-102 or IMG-7289-CTP-201). In the estimation of the Investigator, the risk-benefit favors continued dosing with bomedemstat. Exclusion Criteria: Ongoing participation in another investigational study (except observational studies). A history of non-compliance in a prior bomedemstat study (excluding dose suspensions that were medically warranted). Current use of a prohibited medication (e.g., romiplostim). Medical, psychiatric, cognitive, or other conditions that, in the Investigator's opinion, compromise the patient's safety, ability to give informed consent, or comply with the trial protocol. Females who are pregnant or breastfeeding or plan to become pregnant or breastfeed during the study. Women of childbearing potential (WOCBP) and fertile men unwilling to agree to use an approved method of contraception from time of enrollment until 14 days after last bomedemstat dose.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Bomedemstat<br>Participants will receive bomedemstat daily for 169 days with additional treatment continuing in participants deriving clinical benefit. | Drug: Bomedemstat<br>* Capsule (oral)<br>* Other names: MK-3543;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Number of Participants who Experience an Adverse Event (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. | Up to approximately 3 years | 
| Number of Participants who Experience a Serious Adverse Event (SAE) | An SAE is defined as any AE, whether or not related to the study drug, which results in the following outcomes: Death Life-threatening experience Required or prolonged inpatient hospitalization Persistent or significant disability/incapacity Congenital anomaly Important medical events that, based upon appropriate medical judgment, may jeopardize the participant and may require medical or surgical intervention to prevent one of the outcomes listed above. | Up to approximately 3 years | 
| Number of Participants with Clinically Significant Change from Baseline in One or More Vital Signs | Vital signs will include resting heart rate, semi-supine systolic/diastolic blood pressure, respiratory rate and body temperature. Clinical significance will be determined by the investigator. | Baseline and up to approximately 3 years | 
| Number of Participants with Clinically Significant Changes from Baseline in One or More Laboratory Parameters | Laboratory investigation will include hematology, coagulation, clinical chemistry and urinalysis. Clinical significance will be determined by the investigator. | Baseline and up to approximately 3 years | 
| Myelofibrosis (MF) Participants Only: Change from Baseline in Spleen Volume | Spleen volume will be assessed by magnetic resonance imaging (MRI) (or computed tomography [CT] where applicable) at pre-specified timepoints. Change from baseline in spleen volume will be reported. | Baseline and up to approximately 3 years | 
| Essential Thrombocythemia (ET) Participants Only: Change from Baseline in Platelet Counts | Blood samples will be collected at pre-specified timepoints to determine platelet counts. Change from baseline in platelet counts will be reported. | Baseline and up to approximately 3 years |