Peritransplant Ruxolitinib Administration is Safe and Effective in Patients with Myelofibrosis: a Pilot Open-Label Study.

We report results of our prospective pilot trial (NCT02917096) evaluating safety/feasibility of peri-transplant administration of ruxolitinib for myelofibrosis treatment. Primary objectives were to determine the safety and identify maximum tolerated dose (MTD) of ruxolitinib. Ruxolitinib was given at two dose levels (DL) of 5 and 10mg twice daily, with fludarabine/melphalan conditioning regimen and tacrolimus/sirolimus GVHD prophylaxis. We enrolled 6 and 12 patients in DL-1 and DL-2, respectively. Median age at transplant was 65 years (range:25-73) for all patients. Per DIPSS, 4 patients were at high and 14 were at intermediate risk. PBSCs was the graft source from a matched sibling (n=5) or unrelated (n=13) donor. At each DL one patient developed DLTs: Grade 3 cardiac and GI with Grade 4 pulmonary in DL-1 and Grade 3 kidney injury in DL-2. All patients achieved engraftment. Cumulative incidence (CI) of acute GVHD grade 2-4 and 3-4 were 17% (95% CI: 6-47) and 11% (95% CI: 3-41), respectively. CI of 1-year chronic GVHD was 42% (95% CI: 24-74). With the median follow-up of 22.6 months (range:6.2-25.8) in surviving patients the 1-year overall and progression free survival were 77% (95% CI: 50-91) and 71% (95% CI: 44-87), respectively. Causes of death (n=4) were cardiac arrest, GVHD, respiratory failure, and refractory GVHD of liver. Our results showed that peri-HCT ruxolitinib was safe and well-tolerated with the MTD determined as 10 mg BID, associated with dose-dependent PK and cytokine profile. The early efficacy data are highly promising in this group of high-risk older patients with MF.