Experience with Administration of Ruxolitinib after Allogeneic Stem Cell Transplantation (alloSCT) in Patients with Myelofibrosis

Background:

Ruxolitinib (Rux) is a potent, oral JAK inhibitor that is approved for treatment of intermediate- or high-risk myelofibrosis (MF). Several groups reported on Rux use before alloSCT with primary goals of splenomegaly and constitutional symptom reduction.  There are no data on Rux posttransplant.

Methods:

We retrospectively analyzed the outcomes of patients diagnosed with MF at University of Massachusetts Medical Center who received Rux before and post alloSCT (between 6/2013 and 8/2014).

Results:

Four patients (2 females) were identified; median age was 76 years (49-83) at diagnosis. One patient had primary MF, 3 had secondary MF. One had secondary AML with postPV-MF, 1 had secondary MDS with MF and one had chronic myelomonocytic leukemia with MF. All had constitutional symptoms at diagnosis. Three patients had splenomegaly, 1 had surgical splenectomy before alloSCT. Three patients had received Rux before alloSCT. The median time from Rux to alloSCT was 4 months (0.4-4.9). Two patients received RIC regimen (Fludarabine/Bu2/ATG) and 2 received Thiotepa/Fludarabine/Melphalan with posttransplant cyclosphosphamide. Neutrophils engrafted with median 16 days (12-23). All patients were transfusion independent at day 30 (D30) with >97% donor chimerism in BM. Following the alloSCT Rux was started with median 2.2 months (0.4-8.8) from alloSCT. CMV viremia was detected in one patient before day 100 and one had suspected VZV reactivation at 12 months, in both cases Rux was continued. No EBV reactivation or fungal infection was seen. Three pts had a brief episode of aGVHD (grade I, I and III) of the skin that responded to steroids and immunosupression taper. All the patients are alive in remission at the present time with median post SCT survival of 9.4 months (2.1-18.5).

Conclusion:

Posttransplant Rux appears to be safe and feasible. Further investigation is warranted to elucidate whether improved outcomes are due to a direct effect on the primary marrow disorder, alleviation of  the constitutional symptoms or GvHD.