To the Editor In the phase 3 PERSIST-2 study reported by Mascarenhas et al,1 a Janus kinase 2 (JAK2) inhibitor, pacritinib, was more effective than best available therapy (BAT), including a JAK1 and JAK2 inhibitor, ruxolitinib, for reducing the size of the spleen and subjective symptoms in patients with myelofibrosis who had intermediate- or high-risk disease and moderate to severe thrombocytopenia. We have several concerns about this randomized clinical trial.