As alluded to above, the benefits of ruxolitinib in terms of bone marrow fibrosis reduction and evidence of its anti-clonal activity are modest; of 236 JAK2 V617F+ patients in COMFORT-1, 20 and 6 achieved partial and complete molecular responses (CMR), with median times to response of 22.2 and 27.5 months, respectively.51 This evidence concerns the gene JAK2 and primary myelofibrosis.