Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0039730 (thalassemia)
 10,305 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Hydroxyurea (HU) is one of several agents that have been shown to enhance hemoglobin (Hb) F levels in patients with sickle cell disease and may be useful as a therapy for beta-globinopathies. However, limited information exists on the effects of HU in patients with thalassemia. Accordingly, we examined the hematologic effects of orally administered HU in 13 patients with beta-thalassemia/Hb E, including four patients who had been splenectomized. These patients were treated with escalating doses (final range, 10 to 20 mg/kg/d) for 5 months and were observed in the outpatient hematology clinic every 2 to 4 weeks. Complete blood counts including reticulocyte counts, amounts of Hb E and Hb F, G gamma:A gamma and alpha:non-alpha globin biosynthetic ratios were evaluated before and during treatment. Almost all patients responded with an average increase of 33% in Hb F levels, from a mean (+/- SD) of 42% +/- 11% to 56% +/- 8% (P < .0001), and a reciprocal decline in the percentage of Hb E from 59% +/- 9% to 49% +/- 8% (P < .001). Reticulocytosis was decreased from a mean (+/- SD) of 18.0% +/- 15.6% to 11.7% +/- 9.1% (P < .05); there was also a slight (10%) but statistically significant increase in hemoglobin levels and an improved balance in alpha:non-alpha globin chains ratios. The side effects were minimal in most patients, although these patients tended to tolerate a lower dose of HU before significant myelosuppression than has been our previous experience in sickle cell disease. One splenectomized patient died of sepsis during the trial. We conclude that increased Hb F production in beta-thalassemia/Hb E patients, with an improvement in the alpha:non-alpha globin ratios and, probably, the effectiveness of erythropoiesis, can be achieved using HU. Longer trials of HU in this population, including at other doses and in combination with other agents, appear warranted.
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PMID:Hydroxyurea increases hemoglobin F levels and improves the effectiveness of erythropoiesis in beta-thalassemia/hemoglobin E disease. 856 58

Transfer of drug resistance genes into hematopoietic stem cells (HSCs) has promise for the treatment of a variety of inherited, that is, X-linked severe combined immune deficiency, adenosine deaminase deficiency, thalassemia, and acquired disorders, that is, breast cancer, lymphomas, brain tumors, and testicular cancer. Drug resistance genes are transferred into HSCs either for providing myeloprotection against chemotherapy-induced myelosuppression or for selecting HSCs that are concomitantly transduced with another gene for correction of an inherited disorder. In this review, we describe ongoing experimental approaches, observations from clinical trials, and safety concerns related to the drug resistance gene transfer.
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PMID:Hematopoietic stem cell gene therapy with drug resistance genes: an update. 1603 21

In this chapter, the development of decitabine from its synthesis in 1964 to the submission of a registration file in 2004 is reviewed. The proper application of the unique properties of decitabine took quite some time to elucidate. In addition, the practical handling in the clinic was not easy as the prolonged myelosuppression of decitabine made it difficult to determine the preferred dose and schedule. Laboratory studies on DNA methylation and cell differentiation showed possible applications in solid and hematologic malignancies. However, despite many attempts, results in solid tumors have been disappointing thus far. After thorough investigation, decitabine achieved therapeutic application in myelodysplastic syndrome (MDS), in particular in patients with a poor prognosis. Further indications may include acute myeloid leukemia (AML), chronic myelogenous leukemia (CML), hematopoietic stem cell transplantation, sickle cell anemia, and thalassemia. Whereas most drugs are already at the end of their life cycle after 40 years, decitabine is only at the beginning. Its application will broaden with the increase in knowledge of epigenetic mechanisms and their relationship to drug therapy.
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PMID:Epigenetic drugs: a longstanding story. 1621 83

The biosynthesis of Hb F in place of the deficient Hb A could be a suitable treatment for beta hemoglobinopathies. Among newborn Hb F-Malta-I heterozygotes, it could be shown that the XmnI sequence alone had little, if any effect on gamma-globin gene expression, but interplay with the (AT)(X)T(Y) sites in cis and in trans may occur. In contrast, while the XmnI sequence is clearly correlated with gamma-globin levels in anemic adult beta-thalassemia (thal) homozygotes, the effect on F-erythrocyte numbers and Hb F/F-erythrocyte appears independent of the (AT)(X)T(Y) sites. Even at levels of hydroxyurea (HU) as low as 1.65 mg/kg/day (vs. 10 mg/kg/day on the high dose regime) it can be shown that although even a small increase of Hb F could be obtained, the effect was rarely translated into an increase in circulating hemoglobin (Hb). In most cases, the elevated Hb F level was dependent on the XmnI sequence and was due to increased numbers of F-erythrocytes or Hb F/F-erythrocyte or both. It seems that the bone marrow of thalassemia homozygotes may be more sensitive to myelosuppression by HU possibly due to medullary inflammation. While the data are consistent with loop models of globin switching mechanisms, there is urgent need for large, hypothesis driven, multicenter trials of molecules that could maintain or re-induce high Hb F levels in beta-thal and subject to genetic and epigenetic constraints including inflammation.
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PMID:A review of cis-trans interplay between DNA sequences 5' to the (G)gamma- and beta-globin genes among Hb F-Malta-I heterozygotes/homozygotes and beta-thalassemia homozygotes/compound heterozygotes, and the effects of hydroxyurea on the Hb F/F-erythrocyte; the need for large multicenter trials. 1748 12

Determination of minimal criteria, pre-transplantation regimens, and infusion modalities for effective and reproducible bone marrow (BM) therapy in beta-thalassemia is of fundamental importance for clinical application. In this study, using repopulation assays, we first established the minimal proportion of normal BM stem cells that would result in therapeutic benefit in this red blood cell (RBC) disorder. Eight groups of stable chimeric hemizygous beta-thalassemic (hemi-betathal) mice (10-89%) were systematically subjected to cellular, molecular, and patho-physiologic analyses for approximately 2 years. In the chimeric hemi-betathal groups containing 19-24% normal donor cells, all RBC parameters and consequent erythropoiesis were significantly improved. Mice in the 24% chimeric group and above had marked reduction in organ pathology including iron deposits, and survived to a normal lifespan. Altogether, these results established that a range of 19-24% normal BM cells is sufficient for long-term significant correction of the hemi-betathal phenotype. We also determined concomitantly the minimal myelosuppression radiation doses, the number of cells to be infused, and the number of infusions required in order to attain this therapeutic range in hemi-betathal mice. Importantly, with prior minimal myelosuppression with 1 or 2 Gy, and using cell doses of 40 or 60 millions, 100% of the recipients were successfully engrafted at therapeutic levels, provided the cells were administered in two doses. This study has therefore determined the therapeutic chimeric level as 19-24% of normal cells, and has also defined the minimal transplantation modalities necessary for the stable and successful correction of the hemi-betathal phenotype.
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PMID:Long-term correction of beta-thalassemia with minimal cellular requirement and transplantation modalities. 1751 91

The National Toxicology Program (NTP) Center for the Evaluation of Risks to Human Reproduction (CERHR) conducted an evaluation of the potential for hydroxyurea to cause adverse effects on reproduction and development in humans. Hydroxyurea is a drug used to treat cancer, sickle cell disease, and thalassemia. It is the only treatment for sickle cell disease in children, aside from blood transfusion and, in severe cases, hematopoietic stem cell transplantation. Hydroxyurea is FDA-approved for use in adults with sickle cell anemia to reduce the frequency of painful crises and the need for blood transfusions. Hydroxyurea may be given to children and adults with sickle cell disease for an extended period of time or for repeated cycles of therapy. Treatment with hydroxyurea is associated with known side effects such as cytotoxicity and myelosuppression, and hydroxyurea is genotoxic (can damage DNA). CERHR selected hydroxyurea for evaluation because of: its increasing use for treatment of sickle cell disease in children and adults, knowledge that it inhibits DNA synthesis and is cytotoxic, and published evidence of reproductive and developmental toxicity in rodents. The results of this evaluation are published in the NTP-CERHR Monograph on Hydroxyurea, which includes the NTP Brief and Expert Panel Report on the Reproductive and Developmental Toxicity of Hydroxyurea. Additional information related to the evaluation process, including public comments received on the draft NTP Brief and the final expert panel report, are available on the CERHR website (http:// cerhr.niehs.nih.gov/). See hydroxyurea under "CERHR Chemicals" on the homepage or go directly to http://cerhr.niehs.nih.gov/chemicals/hydroxyurea/hydroxyurea-eval.html). The NTP reached the following conclusions on the possible effects of exposure to hydroxyurea on human reproduction or development. The possible levels of concern, from lowest to highest, are negligible concern, minimal concern, some concern, concern, and serious concern. The NTP expresses serious concern that exposure of men to therapeutic doses of hydroxyurea may adversely affect sperm production. This level of concern is for all males who have reached puberty. The NTP concurs with the Expert Panel that there is concern that exposure of pregnant women to hydroxyurea may result in birth defects, abnormalities of fetal growth, or abnormal postnatal development in offspring. The NTP concurs with the Expert Panel that there is minimal concern that exposure of children to therapeutic doses of hydroxyurea at 5 -15 years of age will adversely affect growth. NTP will transmit the NTP-CERHR Monograph on the Potential Human Reproductive and Developmental Effects of Hydroxyurea to federal and state agencies, interested parties, and the public and make it available in electronic PDF format on the CERHR web site (http://cerhr niehs nih gov) and in printed text or CD from CERHR.
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PMID:NTP-CERHR monograph on the potential human reproductive and developmental effects of hydroxyurea. 1940 58

Hematopoietic stem cells (HSC) are multipotent cells that produce the various lineages of blood and HSC transplantations (HSCT) are widely used to reconstitute damaged bone marrow (BM). Over time, HSCT has evolved for the treatment of non-blood diseases as well, brain in particular. However, HSCT required total myeloablation through irradiation and/or chemotherapy for the treatment of BM-related diseases, and HSCs are difficult to safely deliver in large amounts into the brain. In blood disorders, for a minimal myelosuppression to be sufficient and allow donor cells to engraft, it is necessary to determine the minimal percentage of normal BM cells needed to achieve phenotypic correction. Recent studies on animal models of ?-thalassemia and sickle cell disease (SCD), through Competitive Repopulation Assay (CRA) following lethal irradiation of recipients, demonstrated that an average of 25% normal BM cells allows the production of enough normal red blood cells to significantly correct the ?-thalassemia and SCD phenotypes, at the levels of BM, blood, histology, and survival, with normal donor cells contributing to 50-60% of peripheral red blood cells. Further assays using mild myelosuppression showed that long term sustained phenotypic correction can be obtained for both diseases through a novel transplantation strategy based on modulating four parameters: dose of irradiation/myelosuppression, number of transplanted cells, timing of cell injections, and number of cell doses. Through a minimal dose of irradiation of 1Gy (100 Rads) or 2Gy, two injections of BM cells within the first 24h after myelosuppression resulted in engraftment in 100% of mice and a sustained therapeutic mixed chimerism in ?-thalassemia, while three to four injections were needed to achieve a similar outcome in SCD. Following the success of these trials, we modified this novel HSCT strategy and applied it to determine whether we can protect mice from lethal stroke induced through the Middle Cerebral Artery Occlusion (MCAO). Ischemia/reperfusion resulted in a major infarct that propagated over time to encompass ~70% of the affected hemisphere. When two doses of HSCs were injected at 2h and 24h after the reperfusion, 40% of mice survived, visible neurological defects disappeared, and the infarct size was reduced by two to four fold. Histological examination of brains in surviving mice revealed very few donor cells in the recipient brains, decreased total neurons count and increased glial cell numbers. These data suggest that the neuro-protection was not dependent on cell-supplementation, but rather the protection is manifested likely through growth factor secretion. Combined, these studies create a novel HSCT approach that has proved efficient for the treatment of various disorders. A "window of opportunity" exists for each disease where the donor cells should be administered, and multiple injections of donor HSCs can rescue diseases that would otherwise not be treatable. We hypothesize that the initial injection primes the affected tissue, and subsequent ones help in repair. This new strategy has opened the way for a new era of HSCT for the potential treatments and possibly cures of many diseases.
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PMID:Hematopoietic stem cells: potential new applications for translational medicine. 2515 50

Erythropoiesis is a tightly-regulated and complex process originating in the bone marrow from a multipotent stem cell and terminating in a mature, enucleated erythrocyte.Altered red cell production can result from the direct impairment of medullary erythropoiesis, as seen in the thalassemia syndromes, inherited bone marrow failure as well as in the anemia of chronic disease. Alternatively, in disorders such as sickle cell disease (SCD) as well as enzymopathies and membrane defects, medullary erythropoiesis is not, or only minimally, directly impaired. Despite these differences in pathophysiology, therapies have traditionally been non-specific, limited to symptomatic control of anemia via packed red blood cell (pRBC) transfusion, resulting in iron overload and the eventual need for iron chelation or splenectomy to reduce defective red cell destruction. Likewise, in polycythemia vera overproduction of red cells has historically been dealt with by non-specific myelosuppression or phlebotomy. With a deeper understanding of the molecular mechanisms underlying disease pathophysiology, new therapeutic targets have been identified including induction of fetal hemoglobin, interference with aberrant signaling pathways and gene therapy for definitive cure. This review, utilizing some representative disorders of erythropoiesis, will highlight novel therapeutic modalities currently in development for treatment of red cell disorders.
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PMID:Erythropoiesis: insights into pathophysiology and treatments in 2017. 3013 92