The FDA placed a partial clinical hold on trials of CTI Biopharma Corp.'s lead candidate, pacritinib, citing fatal and life-threatening safety issues in patients treated with the drug vs. those provided best available therapy other than JAK inhibitors in the control arm of PERSIST-1, a phase III study of primary myelofibrosis (MF). The hold also impacts PERSIST-2, an ongoing study extending pacritinib treatment to patients with post-polycythemia vera MF and post-essential thrombocythemia MF.