Treatment for myelofibrosis increasingly incorporates Janus kinase 1 and 2 (JAK1/2) inhibitors. But data has been lacking on when to use JAK1/2 inhibitor when treating patients eligible for stem cell transplantation. A presentation at the 2018 American Society of Clinical Oncology Annual Meeting in Chicago in early June indicated that using JAK1/2 inhibitors prior to stem cell transplantation improves key outcomes in myelofibrosis (MF).
Researchers from Harvard Medical School and the Dana-Farber Cancer Center in Boston performed a retrospective analysis of 132 patients treated for myelofibrosis at Massachusetts General Hospital or the Dana-Farber Cancer Institute between 2004 and 2017. All patients received stem cell transplantation for primary or secondary myelofibrosis, according to the presentation.
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Myelofibrosis, Reticulin Stain (Source: Creative Commons)
The final analysis included 116 patients classified as intermediate 1 (41) and intermediate 2 (75) by the Dynamic International Prognostic Scoring System, as too few patients fell into the low- and high-risk categories. Forty-one of the patients received a JAK1/2 inhibitor before stem cell transplantation, while 75 did not.
In unadjusted analysis, patients who received pre-transplantation JAK1/2 inhibitor therapy had improved overall survival, 75% vs 41%, and progression-free survival, 73% vs 44%. Graft versus host disease-free and relapse-free survival did not improve in the unadjusted analysis, 17% vs 14%, according to the results of the study.
After adjustment for baseline ECOG performance status, intensity of conditioning regimen and Dynamic International Prognostic Scoring System status, pre-transplantation JAK inhibitor use improved progression-free survival 46% and overall survival 47%. The researchers determined that the 23% improvement in graft versus host disease-free and relapse-free survival was not statistically significant.
The authors concluded that “[o]ur data suggest that the use of JAKi prior to [stem cell transplantation] may improve survival outcomes for patients with MF intermediate risk 1 or 2 who undergo [stem cell transplantation].” The researchers noted that additional studies that include more patients are needed to better understand the impact on outcomes of using JAK1/2 inhibitors prior to stem cell transplantation.
The authors also called for further research on post-transplant JAK1/2 inhibitor use, given recent studies that indicate they effectively reduce graft versus host disease severity.
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