To Assess the Safety, Tolerability and Efficacy of Itacitinib Immediate Release Tablets in Participants With Primary or Secondary Myelofibrosis Who Have Received Prior Ruxolitinib and/or Fedratinib Monotherapy (LIMBER-213)

A 2-Part, Phase 2, Open-Label Study of the Safety, Tolerability, and Efficacy of Itacitinib Immediate Release in Participants With Primary Myelofibrosis or Secondary Myelofibrosis (Post-Polycythemia Vera Myelofibrosis or Post-Essential Thrombocythemia Myelofibrosis) Who Have Received Prior Ruxolitinib and/or Fedratinib Monotherapy

This is a 2-part study. In Part 1, participants will be dosed at 2 different dose levels in order to select the RP2D for Part 2 of the study.