KRT-232 Versus Best Available Therapy for the Treatment of Subjects With Myelofibrosis Who Are Relapsed or Refractory to JAK Inhibitor Treatment

Inclusion Criteria:

• Confirmed diagnosis of PMF, post-PV MF or post-ET MF (WHO)
• High, intermediate-2, or intermediate-1 risk Dynamic International Prognostic System (DIPSS)
• Failure of prior treatment with JAK inhibitor
• ECOG ≤ 2

Exclusion Criteria:

• Prior splenectomy
• Splenic irradiation within 3 months prior to randomization
• History of major hemorrhage or intracranial hemorrhage within 6 months prior torandomization
• History of stroke, reversible ischemic neurological defect or transient ischemicattack within 6 months prior to randomization
• Prior MDM2 inhibitor therapy or p53-directed therapy
• Prior allogeneic stem-cell transplant or plans for allogeneic stem cell transplant
• History of major organ transplant
• Grade 2 or higher QTc prolongation (> 480 milliseconds per NCI-CTCAE criteria, version 5.0)