Red Blood Cell Transfusion Independence Following the Initiation of Iron Chelation Therapy in Myelodysplastic Syndrome.

Iron chelation therapy (ICT) is often used to treat iron overload (IOL) in patients (pts) requiring transfusion of red blood cells (RBC) for chronic anemia. In myelodysplastic syndrome (MDS), guidelines recommend consideration of ICT in pts with lower risk International Prognostic Scoring System (IPSS) and IOL as defined by a ferritin level >1000 ug/l; IOL related organ dysfunction; or receipt of ≥20 RBC units. During treatment of a pt with MDS and IOL with ICT, RBC transfusion requirement (TR) ceased. Here we report his course and review reported cases of RBC transfusion independence (TI) or decreased RBC TR in MDS pts receiving ICT.

The pt chart was reviewed and reported cases identified by PubMed search using the terms ‘MDS’ and ‘iron chelation’. The clinical characteristics and course of published cases were summarized.

A 76 year (y) old man was referred in May 2004 for management of MDS diagnosed in 1997, when the white blood cell (WBC) count was 2.4 ×10⁹/l; neutrophils, 0.7 ×10⁹/l; hemoglobin (Hb), 133 g/l; platelets, 108 ×10⁹/l. Bone marrow aspiration and biopsy showed refractory anemia (RA), karyotype analysis 46,X,-Y,+8, and the IPSS score was intermediate-1. The erythropoitin (epo) level was 148.3 mIU/ml and the stem cell assay showed no epo-independent colony growth. In 2004 the Hb dropped to 60 g/l prompting the initiation of RBC transfusion support. He required 3 RBC units every 4 weeks to maintain a Hb >90 g/l and complained of fatigue and functional limitation. Creatinine, bilirubin, TSH, reticulocyte count, B12 and folate levels were all normal. The ferritin level in 2004 was 1293 ug/l and 2197 ug/l in 2006. He declined ICT with deferoxamine (DFO) but in 2006 accepted deferasirox (DFX). He required several dose interruptions and adjustments for renal insufficiency; the current dose is 5mg/kg/d with a normal creatinine. Two months (mo) after starting ICT, the Hb increased spontaneously to 109 g/l and he has not required RBC transfusion since. The mean Hb since starting ICT was 122 g/l and the ferritin decreased to 1082 ug/l in 2009. The most recent neutrophil count was 3.5 ×10⁹/l, platelets consistently clump and the MCV is unchanged at 120 fl. He reports excellent energy and an improved quality of life, and has remained clinically well and RBC transfusion independent to the present, 36 mo from the initiation of ICT.

There are 18 published cases of MDS showing improvement in Hb with ICT; 9 became RBC transfusion independent. Characteristics of the 10 TI pts were: median age at MDS diagnosis 58 (range 18-74) y; male, n=5. MDS subtype: RA, n=5; RARS, n=2, RCMD, n=1; RAEB, n=2. IPSS (reported in 8): low, n=1; int-1, n=5; int-1 or 2, n=1; high, n=1. ICT was: DFO, n=7; DFX, n=3. Median time to RBC TI was 17.5 (1-24) mo and TI duration 13 (3-28) mo to date. Of pts who had decreased RBC transfusion requirements with ICT but did not achieve transfusion independence: median age (reported in 3) was 67 (45-78) y; gender (reported in 3) female, n=3; MDS subtype: RA, n=8; RAEB-t, n=1; IPSS: int-1, n=3; ICT: DFO, n=8; DFX, n=1. Median time to decreased TR was 14.4 (3-24) mo; median duration of decreased TR (reported in 3) 9 (6-32) mo; initial TR 50.9 (19.7-447) g Hb/mo; median decrease in TR 12.7 (0.1-88) g Hb/mo. In one report of 6 pts, 2 with pancytopenia showed improvement with ICT in WBC from 1.4 to 1.9 ×10⁹/l (p<0.0001) and neutrophils from 0.51 to 0.94 ×10⁹/l (p<0.001). The platelet count increased from 16.6 to 22.5 ×10⁹/l (p<0.001) and 14.6 to 29.6 ×10⁹/l (p<0.00001) within 3 mo and the MCV decreased significantly in 5 by a mean of 5.1 (2.1-11.7) fl, normalizing in 2. In a second report, neutrophils increased in 8 of 9 pts; in 4 the initial neutrophil count was <1 ×10⁹/l, and platelet counts increased in 7 of 11 pts, in 4 the initial platelet count was <20 ×10⁹/l.

In summary, our pt is the 19^th patient with MDS reported to date in whom improved Hb followed the initiation of ICT; 9 had a decrease in RBC transfusion requirements, and RBC transfusion independence occurred in 10. The remarkable course of these pts adds to evidence that ICT may be of clinical benefit for selected patients with MDS and IOL. Although the improvement in WBC and platelet counts with ICT in some pts implies a suppressive effect of IOL on hematopoiesis that may be abrogated by ICT, the mechanism by which the effects of ICT on transfusion requirements occur, and the frequency with which they occur, remains an area for future investigation.

Off Label Use: This presentation discusses the use of iron chelation therapy deferoxamine and deferasirox in patients with myelodysplastic syndrome.. Vickars:Novartis Canada: Honoraria, Research Funding. Leitch:Novartis Canada: Honoraria, Research Funding, Speakers Bureau.