A Study of Bomedemstat (IMG-7289/MK-3543) in Participants With Polycythemia Vera (IMG-7289-CTP-203/MK-3543-004)

Duration of Reduction of Hematocrit (Hct) to <45% Without Phlebotomy

Total response duration was defined as the summation of all Hct \<45% response durations, where an individual response duration starts at the timepoint where the Hct \<45% and ends at the first subsequent occurrence of phlebotomy or Hct \>=45%. Hct was analyzed by taking blood samples from participants at designated time points during the study. Duration of reduction of Hct to \<45% without phlebotomy was presented.

Time frame: Up to approximately 22 months

Percentage of Participants With Platelet Count ≤ 450 x 10^9/L by Week 36

Platelet count was analyzed by taking blood samples from participants at designated time points during the study. Participants who enter the study with platelet counts ≤450 X 10\^9/L must achieve an additional on-study platelet count ≤450 X 10\^9/L to be considered responders. A Clopper-Pearson (exact binomial) two-sided 95% confidence interval for the percentage of responders is presented. Baseline data was defined as the data most recently collected prior to the first dose. The percentage of participants who have a platelet count ≤450 X 10\^9/L by week 36 are reported.

Time frame: Up to approximately 36 weeks

Duration of Platelet Count ≤ 450 x 10^9/L

Total response duration was defined as the summation of all platelet ≤450 x 10\^9/L response durations, where an individual response duration starts at the timepoint where platelet count ≤450 x 10\^9/L and ends at the first subsequent occurrence of platelet \>450 x 10\^9/L. Platelet counts were analyzed by taking blood samples from participants at designated time points during the study. The duration of platelet count ≤450 X 10\^9/L in participants are reported.

Time frame: Up to approximately 22 months

Percentage of Participants With White Blood Cell (WBC) Count <10 x 10^9/L by Week 36

WBC count was analyzed by taking blood samples from participants at designated time points during the study. Participants who enter the study with WBC counts \<10 X 10\^9/L must achieve an additional on-study WBC count \<10 X 10\^9/L to be considered responders. A Clopper-Pearson (exact binomial) two-sided 95% confidence interval for the percentage of responders is presented. Baseline data was defined as the data most recently collected prior to the first dose. The percentage of participants who have a WBC count \<10 X 10\^9/L week 36 are reported.

Time frame: Up to approximately 36 weeks

Duration of White Blood Cell (WBC) Count <10 x 10^9/L

Total response duration was defined as the summation of all WBC \<10 x 10\^9/L response durations, where an individual response duration starts at the timepoint when WBC \<10 x 10\^9/L and ends at the first subsequent occurrence of WBC ≥ 10 x 10\^9/L. WBC count was analyzed by taking blood samples from participants at designated time points during the study. The duration of WBC count \<10 X 10\^9/L in participants are reported.

Time frame: Up to approximately 22 months

Number 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 polycythemia vera (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. Baseline data was defined as the data most recently collected prior to the first dose. The number of participants with thrombotic events are reported.

Time frame: Up to approximately 22 months

Number of Participants With Major Hemorrhagic Events

Hemorrhagic events were 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. Baseline data was defined as the data most recently collected prior to the first dose. The number of participants with major hemorrhagic events are reported.

Time frame: Up to approximately 22 months

Number of Participants With an Enlarged Spleen at Baseline Who Had a Reduction in Splenic Volume by 36 Weeks

Spleen volume was measured by magnetic resonance imaging (MRI) (or computerized tomography \[CT\] if participant is not a candidate for MRI) of the abdomen according to standard procedures. Baseline data was defined as the data most recently collected prior to the first dose. The number of participants with an enlarged spleen at baseline (volume \>450 cm\^3) who achieved any reduction in spleen volume by Week 36 are reported.

Time frame: Up to approximately 36 weeks

Number of Participants With Progressive Disease (PD)

PD was defined as the worsening of Polycythemia Vera (PV) to post-PV myelofibrosis, myelodysplastic syndrome or transformation to acute myeloid leukemia. Baseline data was defined as the data most recently collected prior to the first dose. The number of participants with PD are reported.

Time frame: Up to approximately 52 weeks