A Retrospective Real-World Study of the Current Treatment Pathways for Myelofibrosis in the UK (The REALISM UK Study)

Introduction Current treatment options for myelofibrosis (MF) are diverse; apart from rare patients who are eligible for allogeneic transplantation, active treatments are focused on controlling MF-related symptoms and are not disease modifying. Patients who are initially asymptomatic and those at low risk for progression are usually observed without active treatment (watch and wait) until the appearance of symptoms or progression. There are limited real-world data on the management of patients with MF in the United Kingdom (UK). The REALISM UK study documented the early management pathways for patients with MF in routine clinical practice. Method REALISM UK was a multi-centre, retrospective, non-interventional study in 15 UK secondary care centres. Eligible patients were those aged ≥18 years at diagnosis of MF, with diagnosis >6 months and ≤5 years prior to data collection and with ≥1 follow-up visit. Data on patient demographics, clinical characteristics, MF management strategies and outcomes were collected from patients' medical records; the observation period was from the date of MF diagnosis until data collection. The primary endpoint was the time from diagnosis to active treatment. Watch and wait strategies included supportive therapies (blood transfusions, erythropoiesis-stimulating agents, and steroids). Results A total of 200 patients were recruited (63% [n=126/200] with primary MF (PMF); 37% [n=74/200] with secondary MF). The median age at MF diagnosis was 69.7 years (interquartile range [IQR] 63.5-75.7) and 71% (n=141/200) had a JAK2 mutation. At diagnosis, 52% (n=104/200) of patients had International Prognostic Scoring System (IPSS) categories of intermediate-2 (Int-2) or high. Common documented features of disease at diagnosis included an enlarged spleen (47%, n=94/200), anaemia (44%, n=88/200), and constitutional symptoms (e.g. night sweats, unexplained fever, or weight loss [30%, n=60/200]). The median (IQR) time to first active treatment was 46 days (range 0-350) in the total population; patients with higher risk disease were prescribed active treatment sooner: IPSS low, 136.5 days (range 0-625; n=26); IPSS Int-1, 90 days (range 0-494; n=70); IPSS Int-2, 0 days (range 0-252; n=65); IPSS high: 0 days (0-216; n=39). The choice of first management strategy by IPSS at diagnosis is shown in Table 1. During the study period, watch and wait was the first management strategy for 54% (n=107/200) of patients, with the median (IQR) time from diagnosis