Splenectomy following JAK1/JAK2 inhibitor therapy in patients with myelofibrosis undergoing allogeneic stem cell transplantation

Background: Allogeneic hematopoietic stem cell transplantation (alloHSCT) is the only treatment option with curative potential in patients with myelofibrosis (MF). The aim of our study was to evaluate the safety of splenectomy before alloHSCT in MF patients who failed to achieve significant spleen response after ruxolitinib therapy.

Methods: Splenectomy was performed in 12 patients for alloHSCT with myelofibrosis-primary (6 patients), post-polycythemia vera (3 patients). or postessential thrombocythemia (3 patients) between 2016 and 2018. The patients were prospectively included in the study if persistence of splenomegaly ≥ 25 cm was documented after at least 3 months of ruxolitinib therapy. In eight patients subsequent alloHSCT was performed.

Results: Median length of hospital stay was 11 (8-30) days, median follow-up after splenectomy was 20.0 (0.6-31.1) months. No deaths were documented, perioperative morbidity was 50%. Three patients experienced portal vein thrombosis and one experienced splenic vein thrombosis. One patient developed pancreonecrosis and subdiaphragmatic abscess. Mean leukocyte count was significantly higher 1 month after splenectomy than before, 10.7 ± 1.7 versus 6.9 ± 2.3 × 109/L (p = 0.03). Platelets rate significantly elevated starting Day + 7 after splenectomy (p = 0.01). Median time between splenectomy and alloHSCT was 2.6 (0.17-4.5) months. All patients achieved engraftment. In early posttransplant period no cases of severe sepsis, intraabdominal infections were documented. One patient died after alloHSCT due to thrombotic microangiopathy. Seven patients are alive in disease complete remission. No relapses after alloHSCT were observed. Two-year overall survival in the whole group is 90% (95%CI 98-43%).

Conclusion: Splenectomy before alloHSCT might be a promising option in patients who failed to achieve significant spleen response after ruxolitinib therapy.