Patients with beta-thalassemia (Cooley's Anemia) continue to suffer from the sequelae of transfusion-induced iron overload due to the inadequacies of current iron-chelation therapy. Compliance with the use of s.c. desferrioxamine (DFO) continues to be a major problem despite convincing evidence that it markedly reduces morbidity and prolongs life. The full potential of iron-chelation therapy will not be realized until an orally-effective drug is available. We have been conducting metabolic iron balance studies comparing the effectiveness of deferiprone (1,2-dimethyl-3-hydroxypyrid-4-one, DMHP, L1) and N,N'- bis(o-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid (HBED) with that of DFO. While neither of these oral agents has yet fulfilled its promise, it appears likely that both will play a significant role in iron chelation therapy. Our standard DFO regimen (60 mg/kg infused s.c. over 8 hours) placed all patients in net negative iron balance, where balance is the ratio of iron excreted to that received in the form of transfused red cells. DMHP (75 mg/kg p.o. divided t.i.d.) was 60 percent as effective as DFO, 7/13 patients being in net negative iron balance. When deferiprone and DFO were combined, an additive effect was observed in 5/6 patients, synergy in the sixth. 2,3-Dihydroxybenzoic acid (2,3-DHB), another orally effective iron chelator, also had an additive effect when combined with DFO. In both cases, an overall towards urinary iron excretion suggested to us that the bidentate ligand (deferiprone or 2,3-DHB) was accessing pools of iron unavailable to DFO (hexadentate) and was """"""""shuttling"""""""" this iron to the hexadentate """"""""sink."""""""" HBED (80 mg/kg p.o. divided t.i.d.) was less effective than deferiprone, all patients being in positive balance (mean 52 percent). When deferiprone and HBED were combined, synergy was observed in 2/2 patients, both now achieving negative balance where neither was in negative balance on deferiprone alone. These results further support our """"""""iron shuttle"""""""" hypothesis. We suggest combining drugs as a new approach to iron chelation therapy, both to reduce side effects and increase efficacy. If both drugs can be given orally, there is truly a good chance of finding a suitable alternative to DFO. We will further explore this hypothesis using both the hypertransfused rat model of iron overload and clinical studies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
3R01DK055463-05S3
Application #
7111573
Study Section
Special Emphasis Panel (ZHL1)
Program Officer
Wright, Daniel G
Project Start
1999-03-15
Project End
2006-02-28
Budget Start
2003-03-01
Budget End
2006-02-28
Support Year
5
Fiscal Year
2005
Total Cost
$250,000
Indirect Cost
Name
Weill Medical College of Cornell University
Department
Pediatrics
Type
Schools of Medicine
DUNS #
060217502
City
New York
State
NY
Country
United States
Zip Code
10065
Grady, Robert W; Galanello, Renzo; Randolph, Rachel E et al. (2013) Toward optimizing the use of deferasirox: potential benefits of combined use with deferoxamine. Haematologica 98:129-35
Ramos, Pedro; Guy, Ella; Chen, Nan et al. (2011) Enhanced erythropoiesis in Hfe-KO mice indicates a role for Hfe in the modulation of erythroid iron homeostasis. Blood 117:1379-89
Gardenghi, Sara; Ramos, Pedro; Follenzi, Antonia et al. (2010) Hepcidin and Hfe in iron overload in beta-thalassemia. Ann N Y Acad Sci 1202:221-5
Gardenghi, Sara; Grady, Robert W; Rivella, Stefano (2010) Anemia, ineffective erythropoiesis, and hepcidin: interacting factors in abnormal iron metabolism leading to iron overload in ?-thalassemia. Hematol Oncol Clin North Am 24:1089-107
Gardenghi, Sara; Ramos, Pedro; Marongiu, Maria Franca et al. (2010) Hepcidin as a therapeutic tool to limit iron overload and improve anemia in ýý-thalassemic mice. J Clin Invest 120:4466-77
Ramos, Pedro; Melchiori, Luca; Gardenghi, Sara et al. (2010) Iron metabolism and ineffective erythropoiesis in beta-thalassemia mouse models. Ann N Y Acad Sci 1202:24-30
Libani, Ilaria V; Guy, Ella C; Melchiori, Luca et al. (2008) Decreased differentiation of erythroid cells exacerbates ineffective erythropoiesis in beta-thalassemia. Blood 112:875-85
Gardenghi, Sara; Marongiu, Maria F; Ramos, Pedro et al. (2007) Ineffective erythropoiesis in beta-thalassemia is characterized by increased iron absorption mediated by down-regulation of hepcidin and up-regulation of ferroportin. Blood 109:5027-35
Giardina, P J; Grady, R W (2001) Chelation therapy in beta-thalassemia: an optimistic update. Semin Hematol 38:360-6