KRT-232 in Subjects With PMF, Post-PV MF, or Post-ET MF Who Have Failed a JAK Inhibitor

This study evaluates KRT-232, a novel oral small molecule inhibitor of MDM2, for the treatment of patients with myelofibrosis (MF) who no longer benefit from treatment with JAK inhibitor. Inhibition of MDM2 is a novel mechanism of action in MF. This study is a global, open-label Phase 2 study to determine the efficacy and safety of KRT-232 in patients with primary MF, post-polycythemia vera MF, or post-essential thrombocythemia MF who have failed previous treatment with JAK inhibitor (Part A), or Ruxolitinib (Part B). In Part A of the study, patients will be randomly assigned to 2 different doses and 3 different dosing schedules of KRT-232. In Part B of the study, patients will be treated at the recommended dose and schedule from Part A.