Open Journal of Bloo d Di seases, 2011, 1, 3-7
doi:10.4236/ojbd.2011.11002 Published Online September 2011 (
Copyright © 2011 SciRes. OJBD
Is Iron-Chelation Therapy Useful in Persons with
Myelodysplastic Syndrome?
Chaim Hershko1,*, Robert Peter Gale2
1Department of Hematology, Shaare Zedek Medical Center, Jerusalem, Israel; 2Haematology Section, Division of Experimental
Medicine, Department of Medicine, Imperial College, London, UK.
Email: *
Received July 28th, 2011; revised August 29th, 2011; accepted September 6th, 2011.
Iron overload in myelodysplastic syndrome (MDS) results from multiple RBC-trans fusions and inap propriate increased
iron absoption associated with ineffective erythropoiesis. Data from hereditary iron-loading anemias indicate long-
term consequences of iron toxicity are preventable and potentially reversible by effective iron-chelation therapy (ICT).
There is increasing interest in using ICT in persons with MDS because of the recent introduction of orally effective
iron-chelators which are suitable for older persons. Ideally, opinions supporting the benefit of ICT in MDS should be
evidenced-based, especially data from randomized trials showing better survival and, in exceptional cases, improved
heart function. Such data are lacking. Nevertheless, it is possible to rely on the extensive data from trials of ICT in per-
sons with thalassemia and to use well-d efined predictors of increased risks of life-th reatening complicatio ns to identify
persons with MDS most likely to benefit from ICT.
Keywords: Myelodyspla stic Syndrome, MDS, Iron-Chelation, NTBI, Deferoxamine, Deferiprone, Deferasirox,
Transfusion Siderosis
1. Selection of Persons with MDS for
Iron-Chelating Therapy
The choice of persons with MDS who may benefit from
ICT is of continued interest and controversy [1-5]. De-
spite some differences, principles underlying recom-
mendations are remarkably similar for persons with MDS
and those with thalassemia. First, it is recognized that
life-threatening RBC-transfusion-induced iron overload
is only relevant to persons with MDS with a favorable
prognosis. Second, magnitude and rate of iron-accumu-
lation are critical. Substantial heart iron-accumulation is
expected only after about 100 units (U) of RBCs [6-11;
Table 1]. A person receiving 2 - 4 U RBCs monthly will
only be at risk after about 2 - 4 years. Thus, recommend-
dations to start ICT after 20 U RBCs are too liberal and
merits consideration only if the rate of RBC-transfusions
predicts 100 U RBCs in 4 years. Lastly, because se-
rum ferritin in persons with MDS is affected by inflam-
mation, infection and leukemia burden, it is an unreliable
indicator of iron-overload [12,13]. Hence, currently pro-
posed threshold ferritin levels of 1000 - 2500 ng/dL
should be supplemented or replaced by estimates of iron-
overload based on state-of-the-art MRI methodology which
directly assesses tissue iron-accumulation. When such
technology is unavailable, the RBC-transfusion threshold
of 100 U is a practical way to identify persons with
MDS at high-risk of life-threatening iron-accumulation.
The importance of ICT in MDS is not universally ac-
cepted [14]. Although favorable effects of ICT in thalas-
semia include reversal of arrhythmias, improvement in
left ventricular ejection-fraction, arrest of hepatic fibrosis
and decreased glucose tolerance are well-documented, it
is uncertain whether these outcomes apply to persons
with MDS receiving ICT.
2. Choice of Iron-Chelators in Persons with
A comparison of the 3 leading chelators is presented in
Table 2.
Deferox amin e: Because of its proved efficacy and the
extensive experience in persons with thalassemia, defer-
oxamine (DFO) is considered the gold-standard for ICT
[15]. However, compliance with the rigorous require-
ments of daily subcutaneous DFO infusions is a serious
limiting-factor. In practice, elderly persons with MDS are
not reasonable candidates to receive DFO.
Is Iron-Chelation Therapy Useful in Persons with Myelodysplastic Syndrome?
Table 1. Relation of heart iron-accumulation to RBC-transfusion volume in transfused adults without thalassemia.
Buja et al. (1971) Diverse diseases. Clinically-important heart iron accumulation in 60% of subjects after 101 - 200 and 100% of subjects after
201 - 300 U RBCs [6];
Schafer et al. (1981) Anemias. After 60 - 210 U RBCs left ventricular function was impaired in only the most heavily RBC-transfused subjects
Jensen et al. (2003) Diverse diseases. Abnormal heart iron-accumulation in subjects with liver iron concentration >22.3 mg/g dry weight equal to
89 U RBCs * [8];
DiTucci et al. (2008) Anemias. Heart T2* correlated with RBC-transfusions. No subject receiving <290 mL/Kg of PRBCs (equal to 101 U RBCs)
had an abnormal T2* value (< 20 ms) [9];
Chacko J. et al. (2007) MDS. Median RBC-transfusions of 63 and 112 U in persons not receiving or receiving ICT T2* was normal (90%) or
borderline-normal (10%) [10];
Konen E. et al. (2007) MDS. Median RBC-transfusions of 90 U RBCs. All subjects had normal T2 [11].
*Calculated by the Angelucci formula [26] assuming a mean body weight of 75 kg each U RBC representing 200 mg iron.
Table 2. Comparison of iron-chelating drugs [15].
Deferasirox Deferiprone Deferoxamine
373 139 657 MW (Da)
Tridentate Bidentate Hexadentate Chelating property
22.5 19.9 26.6 Iron-binding affinity (pM)
27 7 13 Chelating efficiency (%)
20 - 40 75 - 100 30 - 50 Dose mg/kg/d
Oral, once daily Oral 3 times daily s.c. or i.v. 8 - 12 hours, 5 days/week Route
12 - 16 h 3 - 4 h 20 - 30 min Half-life
High Intermediate Low Lipid solubility
Fecal Urine Urine/fecal Excretion
80 90 - 450 5 - 10 Peak plasma levels (pM)
GI, rash, ocular, auditory, kidneyGI, arthralgia, PMN Ocular, auditory growth, local reactions, allergyAdverse effects
Deferiprone: Because of its smaller size and higher
lipophilicity compared with DFO, deferiprone (DFP)
readily enters cells and may access intracellular chelat-
able iron more effectively than DFO. The cardio-protec-
tive effect of DFP is the most remarkable advantage of
this compound. Weekly WBCs are recommended be-
cause of the risk of drug-induced agranulocytosis. This
complicates the management of ICT in persons with
MDS with disease or treatment-related granulocytopenia.
Deferasirox: DFS is a synthetic iron-chelator with a
plasma half-life of 11-19 hours which allows once-daily
oral dosing. DFS is highly-efficient in removing non-
transferrin bound iron from the blood [16] and is usually
well-tolerated. and is particularly suitable in older per-
sons with MDS. It is premature to conclude whether DFS
improves survival of persons with MDS. Recommended
monitoring includes monthly creatinine and liver func-
tion tests.
Combined Iron-Chelating Drugs: Persons failing
single-drug ICT may respond to a combination of iron-
chelators. There are considerable data on combined drugs
in persons with thalassemia. However, there are insuf-
ficient data to recommend this strategy in persons with
3. Impact of ICT on Survival in MDS
There are few uncontrolled studies reporting the impact
of ICT on survival of persons with MDS. Retrospective
analyses of small studies of persons with MDS receiving
or not receiving ICT suggest better survival amongst the
former [17,18]. The most recent and extensive non-ran-
domized study [19] included 53 subjects receiving ICT
Copyright © 2011 SciRes. OJBD
Is Iron-Chelation Therapy Useful in Persons with Myelodysplastic Syndrome?5
Table 3. Controversies regarding ICT in MDS.
Claim Ambiguity
ICT should be started at serum ferritins 1000-2500 ng/dL. Feritin is an acute phase protein and is unreliable in MDS [12,13].
ICT is indicated when RBC-transfusions 20 U. Clinically-important heart iron-accumulation occurs only after
RBC-transfusions 100 U RBCs in 2-4 years [6-11].
ICT improves survival and prevents leukemia
Non-randomized trial data which may reflect selection biases
Prospective controlled tials of ICT in MDS are
Low compliance and high-rates of competing causes
of morbidity and death in older persons may obscure benefits.
and 44 controls. Median survivals were 124 and 53
months suggesting a benefit for ICT. However, several
potential selection biases and issues complicate this
analysis: 1) causes of death did not differ between the
cohorts; 2) end-of study serum ferritin levels were simi-
lar; 3) persons not receiving ICT were older and had
somewhat worse prognoses; and 4) a higher rate of pro-
gression to AML in the no ICT cohort could reflect a
worse prognosis independent of ICT.
The major limitation of retrospective and non-ran-
domized survival studies is subject selection biases. Per-
sons expected to live long enough to benefit from ICT
are more likely to receive ICT biasing the survival analy-
sis. Although the need for randomized studies is widely
accepted, it is unlikely these will resolve controversy
over using ICT in MDS. The high rate of competing
causes of morbidity and death in older persons with MDS
may obscure a possible benefit of ICT [19]. Conse-
quently, long-term use of ICT will likely rest on
thoughtful initial evaluation of each person considering
relevant clinical data including: 1) likelihood of suffi-
ciently long survival to receive 100 U RBCs within 2
- 4 years; and (2) periodic evaluation of the severity and
distribution of iron-accumulation using state-of-the-art
MRI techniques. Current claims and ambiguities regard-
ing ICT in MDS are summarized in Table 3.
4. Effects of ICT on Hematopoiesis
Improvement in RBC-production in MDS following ICT
was first reported by Jensen et al [20] and confirmed in
several subsequent reports in persons with MDS or
MPN-associated myelofibrosis [21]. This effect is unpre-
dictable and seen with several iron-chelators.
The mechanism responsible for the effect of iron che-
lation on hemoglobin production is unknown. In a person
with homozygous glutaredoxin-5 (GRLX5) mutation
with sideroblast-like microcytic anemia and iron-over-
load, deferoxamine treatment resulted in improved heme
synthesis and the partial correction of anemia [22]. Here,
the likely mechanism of improved hemoglobin synthesis
could be redistribution of mitochondrial iron into the
cytosol following ICT reversing repression of ALA-
synthase-2 translation. This effect may be expected in
only occasional persons with MDS and excessive mito-
chondrial iron deposition. Understanding the underlying
mechanism of this effect may have practical implica-
5. Other Benefits of ICT
A recent review suggested removal of NTBI by ICT may
protect against infection, leukemia transformation and
improve transplant outcomes [23]. These claims should
be interpreted cautiously. As discussed, lower risks of
leukemia transformation may reflect selection-biases [19].
Also, as discussed, increased pretransplant ferritin levels
may reflect co-morbidities adversely affecting transplant
outcome [24] unrelated to iron-overload. Using ICT to
prevent transplant-related infections is particularly haz-
ardous because iron chelators inhibit ribonucleotide re-
ductase and may delay or prevent engraftment [25]. Be-
cause of these considerations, we consider trials of ICT
in unselected persons with MDS ill-advised [23].
6. Conclusions
Development of oral effective iron-chelators suitable for
use in older persons has led to increasing interest in ICT
in persons with MDS. Appropriate selection of persons
with MDS who may benefit from ICT involves several
considerations: 1) RBC-tranfusion-related iron-overload
is only relevant to persons with a favourable prognosis; 2)
clinically-important heart iron-accumulation is expected
only after about 100 U RBCs given over2 - 4 years;
and 3) serum ferritin is a poor indicator of iron-overload
and should be replaced by state-of-the-art MRI tech-
niques. Retrospective analyses of non-randomized and/or
uncontrolled trials of ICT in persons with MDS suggest
ICT results in a decrease in iron-accumulation-related
mortality and, sometimes, decreased RBC-transfusion
rates. However, important selection biases are likely to
operate in these studies. Randomized trials are needed to
determine if there is a survival benefit correlated with
ICT in persons with MDS.
Copyright © 2011 SciRes. OJBD
Is Iron-Chelation Therapy Useful in Persons with Myelodysplastic Syndrome?
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Disclosure: C. H. received travel support and honoraria
from Novartis Basel Switzerland and Apotex Toronto
Canada. RPG is an employee of Celgene Corp, Summit,