A Phase 1 Study of LY5830966 in Participants With Primary Myelofibrosis (PMF), Post-Polycythemia Vera Myelofibrosis (PPV-MF), or Post-Essential Thrombocythemia Myelofibrosis (PET-MF) Who Have Been Failed by a Type I JAK2 Inhibitor (JAK2i)

This is a phase 1, non-randomized, open-label study utilizing a 3+3 sequential dose escalation design followed by an expansion phase. The primary objective will be to evaluate the safety and tolerability of LY5830966 and establish a Maximally Tolerated Dose (MTD) and/or inform the establishment of a candidate Recommended Phase 3 dose (RP3D). The RP3D may be the maximally tolerated dose (MTD) or may be a dose below the MTD. The candidate RP3D will be based on adverse event (AE) pattern, pharmacokinetics (PK) and biomarker information, in addition to all available safety and efficacy data. Expansion cohorts will be enrolled to gather additional safety and efficacy information and to further refine input for future RP3D discussions. Eligible participants will have PMF, PPV-MF or PET-MF and will have either have relapsed after a response, or be refractory to, at least one prior type I JAK2 inhibitor therapy, either administered as monotherapy or in combination with another drug.