A European survey on allogeneic haematopoietic cell transplantation for myelofibrosis on behalf of the Chronic Malignancies Working Party of the EBMT: focus on 'real world' experience of JAK inhibitors, splenomegaly management and novel agents in the transplant algorithm.

Allogeneic haematopoietic cell transplantation (allo-HCT) remains the only potentially curative option for patients with myelofibrosis (MF), yet the integration of JAK inhibitors (JAKi) and novel agents into transplant pathways has created increasing complexity. To capture current real-world practice, the EBMT Chronic Malignancies Working Party conducted a survey of 19 high-volume European centres performing MF allo-HCT. Most centres (68%) routinely initiated JAKi, primarily ruxolitinib, in transplant-eligible patients prior to conditioning, with goals of splenomegaly reduction and symptom control. Management of ruxolitinib intolerance or resistance was heterogeneous, with strategies including switching to alternative JAKi, proceeding directly to allo-HCT, or enroling in clinical trials. Peri-transplant approaches also varied: over half of centres continued ruxolitinib throughout conditioning, while others employed tapering or abrupt discontinuation. Experience with newer JAKi and investigational therapies was limited. Post-transplant, most centres did not routinely reintroduce JAKi, although some used them for relapse or GVHD mitigation. Notably, many centres reported transplant delays due to prolonged medical therapy, with adverse consequences including disease progression. These findings highlight significant heterogeneity in practice, which is likely to increase as more novel agents are integrated in treatment algorithms. Harmonised, multidisciplinary guidelines to optimise timing and outcomes for MF patients eligible for allo-HCT are needed.