骨髓纤维化（MF）是一种克隆性恶性肿瘤，常以贫血为主要特征，且10%至20%的病例会演变为爆发期（BP）。MF患者的贫血与降低生存率有关，并且在原发性MF中也与进展为BP的概率增加有关。对于MF的贫血，常规治疗的效果有限。在一批大部分未接受鲁索利替尼（RUX）治疗的1752例MF患者数据集中，BP发生率为每年2.5%患者。当患者同时具有CTCAE 3/4级和2级贫血（占群体的32%）时，该比率分别达到每年4.3%和4.5%患者。在接受RUX治疗的273例MF患者中，BP发生率为每年2.89%患者，并且在开始RUX治疗时具有CTCAE 2级贫血的患者（占总数的三分之一）中，该比率达到每年4.86%患者。在RUX治疗6个月后依赖输血的患者中（占接受治疗患者的21%），BP发生率为每年4.2%患者。我们的研究突出了贫血MF患者中BP的发生率较高，不论是否使用RUX治疗，其发生率相似。这些发现将有助于治疗医生对新型贫血治疗的安全性做出决策。© 2023 The Authors. eJHaem由英国血液学学会和John Wiley & Sons Ltd.发表。

Myelofibrosis (MF) is a clonal malignancy frequently characterized by anemia and in 10%-20% of cases it can evolve into blast phase (BP). Anemia in MF is associated with reduced survival and -in primary MF- also with an increased probability of BP. Conventional treatments for anemia have limited effectiveness in MF. Within a dataset of 1752 MF subjects largely unexposed to ruxolitinib (RUX), BP incidence was 2.5% patients per year (p-y). This rate reached respectively 4.3% and 4.5% p-y in case of patients with common terminology criteria for adverse events (CTCAE) grade 3/4 and grade 2 anemia, respectively, that represented together 32% of the cohort. Among 273 MF cases treated with RUX, BP incidence was 2.89% p-y and it reached 4.86% p-y in subjects who started RUX with CTCAE grade 2 anemia (one third of total). Within patients with red blood cell transfusion-dependency at 6 months of RUX (21% of the exposed), BP rate was 4.2% p-y. Our study highlights a relevant incidence of BP in anemic MF patients, with a similar rate whether treated with or without RUX. These findings will help treating physicians to make decisions on the safety profile of innovative anemia treatments.© 2023 The Authors. eJHaem published by British Society for Haematology and John Wiley & Sons Ltd.