The overall response rate is 37% (13 of 35 patients: 11 PR [8 CNL and 3 aCML] and 2 CR [2 CNL]). Response rate by mutation status is 50% (10 of 20) in the CSF3R-T618I group...Ruxolitinib provides clinical benefit in at least a third of CNL and aCML patients and is well-tolerated in this patient population. The greatest clinical benefit was among those with CSF3R-T618I mutation.