Midostaurin improves quality of life and mediator-related symptoms in advanced systemic mastocytosis

Background Advanced systemic mastocytosis (advSM) is characterized by the presence of the KIT D816V mutation and pathologic accumulation of neoplastic mast cells (MCs) in various tissues, leading to severe symptoms and organ damage, eg, cytopenias, liver dysfunction, portal hypertension, malabsorption, and weight loss. Treatment with midostaurin, an orally active multikinase/KIT inhibitor now approved for advSM in the United States and the European Union, resulted in a high rate of response accompanied by reduced MC infiltration of the bone marrow and lowered serum tryptase level. Objective We aimed to determine whether midostaurin improves health-related quality of life (QOL) and MC mediator-related symptoms in patients with advSM. Methods In 116 patients with SM (89 patients with advSM fulfilling the strict inclusion criteria of the D2201 study, NCT00782067), QOL and symptom burden were assessed during treatment with midostaurin using the 12-Item Short-Form Health Survey (SF-12) and the Memorial Symptom Assessment Scale (MSAS) patient-reported questionnaires, respectively. MC mediator-related symptoms were evaluated using a specific physician-reported questionnaire. Results Over the first 6 cycles of treatment with midostaurin (ie, 6 months), patients experienced significant improvements in total SF-12 and MSAS scores, as well as in subscores of each instrument. These improvements were durable during 36 months of follow-up. Similarly, we found substantial improvements (67%-100%) in all MC mediator-related symptoms. Conclusion QOL and MC mediator-related symptoms significantly improve with midostaurin treatment in patients with advSM.