Study design.^aPatients were enrolled with earlier versions of the protocol with the following differences in key inclusion criteria: Hb level <10 g/dL (protocol amendment 4, 25 August 2020); treated with ruxolitinib for ≥24 weeks and at a stable dose for ≥8 weeks before study entry (protocol amendment 6, 20 July 2021). ^bAs the enrollment was permanently halted, based on protocol amendment, an extension treatment phase was added to part 1 for eligible and benefitting patients from part 1. ^cDose escalation to determine the phase 2 dose for the siremadlin and rineterkib arms (already known for other agents). ^dThe NIS793 arm had a 21-day cycle; all other arms had a 28-day cycle. ^ePatients were to be treated with combination therapy for 12 weeks, followed by novel agent monotherapy. ^fThe ruxolitinib dose was to be neither escalated nor de-escalated and should have remained fixed at the stable dose during part 1 of the study. ^gRineterkib was tested only at 200 mg in the actual study, but the study design had other potential options stated in the event of dose escalation or reduction. BID, twice daily; C1D15, cycle 1 day 15; CT, computed tomography; Hb, hemoglobin; MRI, magnetic resonance imaging; PET-MF, post–essential thrombocythemia myelofibrosis; PMF, primary myelofibrosis; PPV-MF, post–polycythemia vera myelofibrosis; QD, once daily; Q3W, every 3 weeks; Q4W, every 4 weeks.