Improved survival in red blood cell transfusion dependent patients with primary myelofibrosis (PMF) receiving iron chelation therapy.

ABSTRACT

Many patients with primary myelofibrosis (PMF) become red blood cell (RBC) transfusion dependent (TD), risking iron overload (IOL). Iron chelation therapy (ICT) may decrease the risk of haemosiderosis associated organ dysfunction, though its benefit in PMF is undefined. To assess the effect of TD and ICT on survival in PMF, we retrospectively reviewed 41 patients. Clinical data were collected from the database and by chart review. The median age at PMF diagnosis was 64 (range 43-86) years. Median white blood cell (WBC) count at diagnosis was 7.6 (range 1.2-70.9) x 10(9)/L; haemoglobin 104 (62-145) G/L; platelets 300 (38-2088) x 10(9)/L. Lille, Strasser, Mayo and International Prognostic System (IPS) scores were low risk, n = 15, 8, 11, 3; intermediate, n = 15, 19, 9, 16; high, n = 5, 11, 5, 7; respectively. Primary PMF treatment was supportive care, n = 23; hydroxyurea, n = 10; immunomodulatory, n = 4; splenectomy, n = 2. Sixteen patients were RBC transfusion independent (TI) and 25 TD; of these 10 received ICT for a median of 18.3 (0.1-117) months. Pre-ICT ferritin levels were a median of 2318 (range 263-8400) and at follow up 1571 (1005-3211 microg/L (p = 0.01). In an analysis of TD patients, factors significant for overall survival (OS) were WBC count at diagnosis (p = 0.002); monocyte count (p = 0.0001); Mayo score (p = 0.05); IPS (p = 0.02); number of RBC units (NRBCU) transfused (p = 0.02) and ICT (p = 0.003). In a multivariate analysis, significant factors were NRBCU (p = 0.001) and ICT (p = 0.0001). Five year OS for TI, TD-ICT and TD-NO ICT were 100, 89 and 34%, respectively (p = 0.003). The hazard ratio (HR) for receiving >20 RBCU was 7.6 (95% Confidence Intervals [CI] 1.2-49.3) and for ICT was 0.15 (0.03-0.77). In conclusion, 61% of PMF patients developed RBC-TD which portended inferior OS; however patients receiving ICT had comparatively improved OS, suggesting a clinical benefit. Prospective studies of IOL and the impact of ICT in PMF are warranted.