Bone Marrow Iron Concentration as a Marker of Iron Accumulation and Marrow Expansion in Patients with Beta Thalassemia Major.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1852-1852
Author(s):  
Paola Polchi ◽  
Rossella Palmieri ◽  
Marco Andreani ◽  
Javid Gaziev ◽  
Cecilia Alfieri ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Iron Content ◽  
Iron Concentration ◽  
Iron Chelation ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
H63d Mutation ◽  
Class 1 ◽  
Bone Marrow Iron ◽  
Marrow Expansion

Abstract Liver iron concentration (LIC) is a known and accurate marker of iron accumulation and is widely utilized to monitor iron chelation therapy in multiply transfused patients with Beta thalassemia major. Iron concentration in the bone marrow has not been studied and reported before. We utilized atomic absorption spectrophotometry to measure the iron content of marrow biopsy (BIC) in 102 thalassemia patients in various phase of treatment, 74 of them during the course of the disease and 28 patients after successful allogeneic marrow transplant. We observed BIC values below 0.5 mg/g dry weight in 7 healthy donors used as controls. Mean and median BIC were 4.67 and 2.70 (range 0.05 – 59.9) mg/g dw, in 101 valuable patients. Bone Marrow iron concentration (BIC) was calculated at the same time of LIC for each patient and a ratio LIC/BIC was generated. LIC/BIC ratio below 3, ratio between 3 and 10, and above 10 identified three categories of patients each with significant linear correlation between LIC and BIC (0.74; 0.76; 0.81 respectively). Twenty eight patients were in the first category, 48 in the second, and 25 in the third. Mean BIC was 9.47, 3.7, 1.2 mg/g dw and mean LIC was 12.7, 19.6, 22.3 mg/g dw respectively for CAT1, CAT2 and CAT3. Patients were also classified in class of risk for transplant, based on hepatomegaly, presence of liver fibrosis and history of regular or irregular iron chelation. BIC was higher in class 3 patients and in the irregularly chelated patients. Patients in class 1 were prevalently in CAT1 or 2, patients in class 3 were prevalently in CAT2 or 3. BIC value in each of the 3 categories correlated significantly with the whole body iron (WBI) amount, and WBI was significantly different in the three categories being lower in CAT1, that have higher BIC ( 3927 mg; 5894 mg, 7030 mg in CAT1, 2 and 3; p 0.01). Iron chelation quality (regular vs irregular) correlated with BIC value and with BIC category, majority of regularly chelated patients were in the Category 1 vs Category 2 or 3 (p 0.01). Patients before transplant were prevalently in CAT1 and 2, while those post transplant were mostly in CAT3, twelve patients that were studied both before and after transplant, changed from cat 1 to 2 or from cat 2 to 3. Their BIC changed significantly decreasing after BMT (median BIC was 7.8 before transplant and 2.25 after, p=0.002) To investigate the role of genetic hemochromatosis mutations, H63D region and Hamp region in 63 patients were also studied. Mean BIC was 3.08 in 16 patients with H63D mutation compared to 5.59 in those without mutation, and 11/16 had BIC below the median, p=0.03. Significantly more patients with H63D mutation were in CAT3 (p 0.02). Apparently H63D mutation favours accumulation of iron in the body, that was higher in CAT3, but participate also to lowering utilization of introduced iron. In conclusion, patients in category 1 had lower LIC and higher BIC, comprehended 50% of the patients in class 1 of risk, and 45% of the regularly chelated patients. On the contrary, majority of patients post transplant independently of having or not performed an iron removal program were in CAT3. We can draw conclusion that BIC related categories, as described here, give information on the balance between accumulation and utilization of iron. Patients belonging to BIC-Cat 1 correspond to patients that have been treated adequately and with lower iron body burden, better chelation history. They have higher BIC value and lower LIC value. They also are in pre-transplant phase, with active beta-thalassemia, when ineffective erythropoiesis and marrow expansion are more prominent. Further studies will be necessary to confirm the association of marrow iron content with the marrow functionality and expansion.

Thiotepa in the Conditioning Regimen Decreases Rejection after HLA Identical Allogeneic Marrow Transplantation in Children with Beta Thalassemia Major Aged Less Then 4 Years

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 4598-4598
Author(s):  
Paola Polchi ◽  
Javid Gaziev ◽  
Guido Lucarelli ◽  
Pietro Sodani ◽  
Cecilia Alfieri ◽  
...  
Keyword(s):  
Relapse Rate ◽  
Conditioning Regimen ◽  
Iron Chelation ◽  
Rejection Rate ◽  
Thalassemia Major ◽  
Organ Damage ◽  
Beta Thalassemia ◽  
Beta Thalassemia Major ◽  
Gvhd Prophylaxis ◽  
Class 1

Abstract BMT in children with beta thalassemia major is the only form of definitive cure with correction of the genetic disease in a relevant proportion of patients, and long term thalassemia free survival. Lucarelli and coll. showed since 1986 that transplant performed early in the course of disease gives high chance of cure, and a system of class definition was reported in 1990 identifying as in class 1 patients without any evidence of organ damage, based on hepatomegaly, presence of liver fibrosis and history of regular or irregular iron chelation. Majority of children aged less then four years were then in class 1 and occasionally in class 2. Thiotepa has been introduced in the conditioning regimen of children less then 4 y.o. in the attempt to decrease the rejection rate in this category of good prognosis patients. Out of 519 children affected by not advanced Beta Thalassemia Major, either in class 1 or 2 of risk, with an HLA identical sibling donor, 25 patients aged 1 to 4 yo received an intensified conditioning regimen including thiotepa 10 mg/kg given in one day, in addition to standard BUS-CY regimen called PC 6. This was based on the observation that children aged below 4 transplanted after the standard PC 6 had significantly higher relapse rate with return to thalassemic pre transplant condition (OS, TFS, REJ were 87%; 86%; 4% vs 87%; 73%; 14% in children aged above or below 4 yo respectively (n=398 =>4; n=96 < 4). The increased relapse rate was more relevant in children treated with standard PC 6 and GVHD prophylaxis performed using short MTX plus CSA versus those who received cyclosporine alone. The GVHD prophylaxis protocol including sMTX + CSA +Pred, used after 1999 for all patients in our practice significantly improved OS, lowered GVHD rate, but had a trend toward increased rejection rate. This trend was more evident in children aged less than 4 despite an increased dose of Busulfan (16 mg/kg total) was already in use for younger children. Therefore, since 2003 we introduced Thiotepa for children less then 4 yo, maintaining the GVHD prophylaxis with sMTX and CSA. In the last group of 25 children aged below 4 receiving the intensified protocol, 1 patient rejected the graft and had thalassemia recovery, one died of GVHD and infection, and 23 are alive and cured. Actuarial probability of OS, TFS, Rejection were 96%; 91%, 5%. These results favourably compare to the previous results in this category of patients, confirming that Thiotepa exerts additional immunosuppressive and eradicating action, counteracting the effect of GVHD prophylaxis with sMTX+CSA, that exerts an action favouring rejection.

Monitoring Cardiac Siderosis in Patients with Beta-Thalassemia Major on Various Chelation Regimens,

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 3177-3177
Author(s):  
Srikanth R. Ambati ◽  
Rachel Randolph ◽  
Kevin Mennitt ◽  
Dorothy A Kleinert ◽  
Patricia Giardina
Keyword(s):  
Iron Overload ◽  
Serum Ferritin ◽  
Iron Concentration ◽  
Iron Chelation ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Liver Iron ◽  
Beta Thalassemia Major ◽  
Cardiac Siderosis ◽  
Hepatic Iron Overload

Abstract Abstract 3177 Background: Patients with Beta-thalassemia major develop progressive iron overload in various organs. Cardiac siderosis is a major cause of mortality and morbidity in these patients, and also poses a significant treatment challenge. Methods: We have reviewed 101 beta-thalassemia major patients 39 Male (M) 62 Female (F) with a mean age of 27.9 (range: 2 to 60 years). All received regular transfusions to maintain pre transfusion Hb levels of 9 to10 gm/dl and all received iron chelation initially with deferoxamine (DFO) and subsequently treated with deferasirox (DFX) or deferiprone (DFP) in combination with DFO. Each patient was monitored yearly for iron excess by hepatic and cardiac magnetic resonance imaging (MRI) T2*. They were also assessed with monthly evaluations for liver and renal function (Bili, AST, ALT, BUN, Creatinine), serum ferritin, CBC (or weekly if on DFP), and urinalysis. Annual EKG, ECHO, hearing and vision testing and endocrine evaluations were also performed. The patients were grouped according to the severity of cardiac siderosis. Mild to moderate cardiac siderosis was defined as a T2* 12–20 msec and severe cardiac siderosis T2*≤ 11 msec. Annual studies were compared using paired student T test and repeated measures Analysis Of Variance (ANOVA) when necessary. Patient population: Twenty one of the 101 patients (7M and 14F) with a mean age of 30.6 yr, age range 15 to 56 yr, had abnormal cardiac T2* of <20 msec and three or more subsequent annual cardiac T2* measurements. Thirteen patients, 3 M 10 F with a mean age of 33 (range: 19 to 60), had severe cardiac siderosis and 8 patients, 3 M 5 F with mean age of 38 (range: 25 to 49), had mild-moderate cardiac siderosis. During the course of the observation their iron chelation therapy was optimized to reduce serum ferritin levels < 1500 μg/dl and to reduce or maintain liver iron concentration (LIC) ≤ 7 mg/gm dw. Data analysis: At the time of their first annual MRI study (baseline), 8 patients were on DFO of which 6 were switched to DFX, 13 patients were on DFX, 11 patients were dose escalated on DFX, and 4 patients were switched to combination chelation with DFO and DFP. At baseline, patients with severe cardiac siderosis had a mean cardiac T2* level = 7.4 ± 0.47 SEM (range: 4.6 to 11msec). Over the treatment course of 6 years annual cardiac T2* levels consistently improved and by 6 years cardiac T2* reached a mean level =14.3 ±1.5 SEM (range: 12 to 17 ms) (Fig 1). Those patients who at baseline had a mild to moderate cardiac siderosis with mean cardiac T2* of 14.6 ± 1.02 SEM (range: 12 to 19 msec) improved by 3 years of treatment when they achieved a mean cardiac T2* of 26.3 ± 3.4 SEM (range of 16 to 42 msec) (Fig 2). Liver iron concentration (LIC) was measured annually by MRI. Initially the majority, 16 out of 21 of patients, had hepatic iron overload LIC ≤ 10 mg/ gm dw of whom 56% (9 of the 16) had severe cardiac siderosis. 5 of 21 patients had a LIC > 15 mg/ gm dw of whom 80% (4 out of 5) patients had severe cardiac siderosis (Fig 3). Patients with LIC ≤10 mg/ gm dw had ferritin levels ranging from 166 to 3240 μg/ dl and patients with LIC >15 mg/ gm dw had elevated serum ferritin levels of 1180 to 17,000 μg/ dl. Patients with severe cardiac siderosis had mean MRI ejection fraction (EF)= 55.8% (range: 31 to 70%) while patients with mild to moderate cardiac siderosis had mean MRI EF= 60% (range: 53 to 66%). One patient with severe cardiac siderosis was recovering from symptomatic congestive heart failure. Conclusion: Cardiac siderosis can be noninvasively diagnosed utilizing MRI T2* techniques and subsequently to monitor treatment. The majority of patients improve cardiac T2* over time with optimal chelation therapy. Severe cardiac siderosis occurs even with mild to moderate hepatic iron overload. Left ventricular EF may not predict severe cardiac siderosis. Therefore it is important to annually monitor cardiac siderosis with MRI T2*. Disclosures: No relevant conflicts of interest to declare.

scholarly journals CURING HEMOGLOBINOPATHIES: CHALLENGES AND ADVANCES OF CONVENTIONAL AND NEW GENE THERAPY APPROACHES.

2019 ◽  
Vol 11 (1) ◽  
pp. e2019067 ◽  
Author(s):  
Irene Motta ◽  
Valentina Ghiaccio ◽  
Andrea Cosentino ◽  
Laura Breda
Keyword(s):  
Quality Of Life ◽  
Health Care ◽  
Gene Therapy ◽  
Bone Marrow ◽  
Iron Chelation ◽  
Beta Thalassemia ◽  
Allogenic Bone ◽  
Number Of Patients ◽  
Monogenic Diseases

Inherited hemoglobin disorders, including beta-thalassemia (BT) and sickle-cell disease (SCD) are the most common monogenic diseases worldwide, with a global carrier frequency of over 5%. With migration they are becoming more common worldwide, making their management and care an increasing concern for health care systems. BT is characterized by an imbalance in the α/β-globin chain ratio, ineffective erythropoiesis, chronic hemolytic anemia, and compensatory haemopoietic expansion. Globally, there are over 25,000 births each year with transfusion-dependent thalassemia (TDT). The current available treatment for TDT is lifelong transfusions and iron chelation therapy or allogenic bone marrow as curative option. SCD affects 300 million people worldwide  and severely impacts the quality of life of patients, who experience unpredictable, recurrent acute and chronic severe pain, stroke, infections, pulmonary disease, kidney disease, retinopathy, and other complications. While survival has been dramatically extended, quality of life is markedly reduced by disease- and treatment-associated morbidity. The development of safe, tissue specific and efficient vectors, and efficient gene editing technologies have led to the development of several gene therapy trials for BT and SCD. Yet, the complexity of the approach presents its hurdles. Fundamental factors at play include the requirement for myeloablation on a patient with a benign disease, the age of the patient and consequent bone marrow microenvironment. A successful path from proof-of-concept studies to commercialization must render gene therapy a sustainable and accessible approach for a large number of patients. Furthermore, the cost of these therapies is a considerable challenge for the health care system. While new promising therapeutic options are emerging and many others are on the pipeline5, gene therapy can potentially cure patients. We herein provide an overview of the most recent potentially curative therapies for hemoglobinopathies and a summary of the challenges that these approaches entail.

Fibroblast Growth Factor 23 (FGF23) and Klotho Protein in Beta-Thalassemia

2020 ◽  
Vol 52 (03) ◽  
pp. 194-201
Author(s):  
Dimitrios Stefanopoulos ◽  
Narjes Nasiri-Ansari ◽  
Ismene Dontas ◽  
Andromachi Vryonidou ◽  
Antonis Galanos ◽  
...  
Keyword(s):  
Growth Factor ◽  
Fibroblast Growth Factor ◽  
Fibroblast Growth Factor 23 ◽  
Iron Chelation ◽  
Thalassemia Major ◽  
The Body ◽  
Beta Thalassemia ◽  
Fibroblast Growth ◽  
Control Subjects ◽  
Number Of Patients

AbstractDerangements in phosphate and calcium homeostasis are common in patients with beta-thalassemia. Fibroblast growth factor 23 (FGF23) is among the main hormones regulating phosphate levels, while several studies underline an interplay between iron (Fe) and FGF23. Herein, we investigated, for the first time, the serum intact molecule (iFGF23) and the carboxyl-terminal fragment (C-FGF23) and Klotho levels simultaneously in patients with beta-thalassemia major receiving iron chelation regimens in comparison to healthy control subjects. We also correlated them with the body iron burden. The observational case-control study included 81 subjects (40 thalassemic patients and 41 healthy controls). Serum iFGF23, C-FGF23 and Κlotho were measured by ELISA. Parathormone, 25-hydroxycholecalciferol, calcium, and phosphorus were measured in blood and/or urine. The degree of hemosiderosis was evaluated by assessing the serum ferritin levels and performing T2* MRI measurements. Serum C-FGF23 levels were significantly lower in patients compared to control subjects (p=0.04), while iFGF23 and Klotho levels did not differ. Serum C-FGF23 levels were negatively correlated with ferritin (r=–0,421, p=0.018), whereas there were no significant correlations of each of the three factors with the iron chelation therapy. Decreased serum C-FGF23 levels were found in βTh patients which may be attributed to inhibition of proteolytic cleavage of iFGF23. Further studies in a greater number of patients will shed more light on the disturbances of the iFGF23, Klotho and C-FGF23 in thalassemia and their possible role in bone disease of such patients.

scholarly journals Globin Chain Synthesis in the Marrow and Reticulocytes of Beta Thalassemia, Hemoglobin H Disease, and Beta Delta Thalassemia

Blood ◽  
1972 ◽  
Vol 40 (1) ◽  
pp. 105-111 ◽  
Author(s):  
Mordechai Shchory ◽  
Bracha Ramot
Keyword(s):  
Bone Marrow ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Globin Chain ◽  
Thalassemia Intermedia ◽  
Thalassemia Minor ◽  
Order Of Magnitude ◽  
Hb H Disease ◽  
Chain Synthesis ◽  
Globin Chain Synthesis

Abstract α, β, and γ globin chain synthesis in bone marrow and peripheral blood reticulocytes were studied in two patients with thalassemia major, two with thalassemia intermedia, one with thalassemia minor, one with Hb H disease, and one with homozygous βδ-thalassemia. Nine nonthalassemic patients served as controls. In thalassemia major, a marked imbalance of α- to β-chain synthesis was found in the bone marrow as well as in reticulocytes. The imbalance, however, was slightly more evident in the latter. In the patients with thalassemia intermedia and minor the α- to β-globin chain ratios in the reticulocytes were of the same order of magnitude, despite the marked clinical differences between thalassemia intermedia and minor. A balanced synthesis was found in the bone marrow of the patient with thalassemia minor. The bone marrow globin synthesis in thalassemia intermedia was not studied. Contrary to that in Hb H disease and βδ-thalassemia, the imbalance was more apparent in the bone marrow. In the latter, no evidence for imbalance was detected in the reticulocytes. These results point out the need for further studies on globin chain synthesis in the bone marrow and reticulocytes of patients With the various thalassemia syndromes and the effect of the free globin chain pool on those results.

Iron chelation with deferasirox in adult and pediatric patients with thalassemia major: efficacy and safety during 5 years' follow-up

Blood ◽  
2011 ◽  
Vol 118 (4) ◽  
pp. 884-893 ◽  
Author(s):  
M. Domenica Cappellini ◽  
Mohamed Bejaoui ◽  
Leyla Agaoglu ◽  
Duran Canatan ◽  
Marcello Capra ◽  
...  
Keyword(s):  
Adverse Events ◽  
Iron Concentration ◽  
Iron Chelation ◽  
Dry Weight ◽  
Thalassemia Major ◽  
Efficacy And Safety ◽  
Liver Iron ◽  
Median Serum

Abstract Patients with β-thalassemia require lifelong iron chelation therapy from early childhood to prevent complications associated with transfusional iron overload. To evaluate long-term efficacy and safety of once-daily oral iron chelation with deferasirox, patients aged ≥ 2 years who completed a 1-year, phase 3, randomized trial entered a 4-year extension study, either continuing on deferasirox (deferasirox cohort) or switching from deferoxamine to deferasirox (crossover cohort). Of 555 patients who received ≥ 1 deferasirox dose, 66.8% completed the study; 43 patients (7.7%) discontinued because of adverse events. In patients with ≥ 4 years' deferasirox exposure who had liver biopsy, mean liver iron concentration significantly decreased by 7.8 ± 11.2 mg Fe/g dry weight (dw; n = 103; P < .001) and 3.1 ± 7.9 mg Fe/g dw (n = 68; P < .001) in the deferasirox and crossover cohorts, respectively. Median serum ferritin significantly decreased by 706 ng/mL (n = 196; P < .001) and 371 ng/mL (n = 147; P < .001), respectively, after ≥ 4 years' exposure. Investigator-assessed, drug-related adverse events, including increased blood creatinine (11.2%), abdominal pain (9.0%), and nausea (7.4%), were generally mild to moderate, transient, and reduced in frequency over time. No adverse effect was observed on pediatric growth or adolescent sexual development. This first prospective study of long-term deferasirox use in pediatric and adult patients with β-thalassemia suggests treatment for ≤ 5 years is generally well tolerated and effectively reduces iron burden. This trial was registered at www.clinicaltrials.gov as #NCT00171210.

scholarly journals P0861THE RELATIONSHIP BETWEEN HEPCIDIN-25 AND BONE MARROW IRON IN ANEMIC, NON-DIALYSIS, CHRONIC KIDNEY DISEASE PATIENTS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Cristina-Stela Capusa ◽  
Ana-Maria Mehedinti ◽  
Gabriela-Adriana Talimba ◽  
Ana Stanciu ◽  
Liliana Viasu ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Bone Marrow ◽  
Kidney Disease ◽  
Linear Regression ◽  
Iron Content ◽  
Blood Smear ◽  
Transferrin Saturation ◽  
Peripheral Blood Smear ◽  
Iron Stores ◽  
Bone Marrow Iron

Abstract Background and Aims Hepcidin-25 (Hep25) is a key known regulator of iron metabolism and its interactions with inflammation, iron stores and erythropoietic activity were involved in the pathogenesis of chronic kidney disease (CKD)-associated anemia. Therefore, our aim was to assess the determinants of serum Hep25 level in non-dialysis CKD patients. Method In this cross-sectional, single-center study, 52 subjects (56% men, 65±13 years) with CKD [estimated glomerular filtration rate, eGFR 14.5 (95%CI 16 to 25) mL/min] and anemia [hemoglobin, Hb 9.8 (95%CI 9.2 to 9.9) g/dL], not treated with erythropoiesis-stimulating agents (ESA) or iron in the previous 6 months, were enrolled. Patients with anemia of other causes than CKD, active infectious and inflammatory diseases, malignancy, severe hyperparathyroidism, transfusions during the last 3 months, and immunosuppressive therapy were excluded. The iron status was evaluated using both peripheral and central parameters. The iron stores were assessed by serum ferritin (Fer) and iron content in bone marrow macrophages (iMf, measured quantitively on a scale from 0 to 6). The iron available for erythropoiesis was assessed by transferrin saturation (TSAT) and the percentage of sideroblasts (%Sb). Anemia was further evaluated by a peripheral blood smear, erythrocytes indices and reticulocyte index. Serum Hep25 and erythropoietin (Epo) were assessed by ELISA (Bachem®, and Abcam® 119522, respectively). C-reactive protein (CRP), albumin, and parameters of kidney disease (eGFR, proteinuria) were also measured. Mann-Whitney, Kruskal-Wallis, Chi2 tests, Spearman bivariate correlation and multiple linear regression were used for statistical analysis. Results The median serum Hep25 of the whole cohort was 82.1 (95%CI 68.7 to 92.1) ng/mL. According to median Hep25, subjects were clustered in Group 1 (below median - G1) and Group 2 (above median - G2). %Sb and reticulocyte index had higher levels in G2 than in G1 [9 (95%CI 5 to 14) vs. 5 (95%CI 4 to 7) %, p=0.003 and 0.55 (95%CI 0.39 to 0.77) vs. 0.41 (95%CI 0.32 to 0.58), p=0.05, respectively], while the proportions of subjects with iMf suggestive for iron deficiency or iron overload were similar in G2 and G1 (38% vs. 50%, p=0.40, and 26% vs. 23%, p= 0.75, respectively). Peripheral blood smear, peripheral iron indices and all the other studied parameters were also alike. In bivariate analysis, Hep25 was positively associated both with indices of iron stores, i.e. Fer (rs = 0.30, p=0.03) and iMf (rs = 0.34, p=0.01) and indices of iron available for erythropoiesis, i.e. %Sb (rs = 0.55, p&lt;0.001) and (marginally) with TSAT (rs = 0.26, p=0.06). Meanwhile, Hep25 was not related to serum Epo, CKD parameters or inflammation markers. In a multivariate linear regression model that explained 28% of Hep25 variation, the percentage of bone marrow sideroblasts, i.e. the tissue iron available for erythropoiesis, was the only independent determinant of Hep25: Variables entered in the first step: reticulocyte index, percentage of medullary sideroblasts (%Sb), iron content in the bone marrow macrophages (iMf), serum ferritin, and transferrin saturation Conclusion In stable patients with advanced CKD, not treated with ESA or iron, with low to moderate inflammation, serum hepcidin was related only to bone marrow iron available for erythropoiesis, suggesting that in this clinical setting the need of iron for erythropoiesis prevails over inflammation in regulation of hepcidin synthesis.

Pharmacogenetics of Cyclophosphamide in Patients with Beta Thalassemia Major Undergoing Bone Marrow Transplantation.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 99-99
Author(s):  
Balasubramanian Poonkuzhali ◽  
Desire Salamun ◽  
Ramachandran V. Shaji ◽  
Biju George ◽  
Vikram Mathews ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Transplantation ◽  
Individual Variation ◽  
Marrow Transplantation ◽  
Systemic Exposure ◽  
Thalassemia Major ◽  
Beta Thalassemia ◽  
Mutant Genotype ◽  
Beta Thalassemia Major ◽  
Homozygous Mutant

Abstract Cyclophosphamide (Cy) is commonly used in conditioning therapy for bone marrow transplantation (BMT). The conversion of Cy to its first active metabolite 4-hydroxy cyclophosphamide (4-HCy) is mediated by several enzymes of the cytochrome P450 (CYP450) family [CYP2B6, 2C9, 2C19 and 3A4]. Since the pharmacokinetics (PK) of 4-HCy is formation rate limited, the AUC ratio of 4-HCy/Cy reflects better the degree of systemic exposure to 4-HCy. The PK of Cy and HCy exhibits up to 20 fold inter-individual variation in patients during conditioning. To understand the mechanisms underlying the variation in Cy metabolism, we analyzed the PK of Cy and 4-HCy in 40 consecutive patients with beta thalassemia major undergoing BMT and correlated them with the common polymorphisms of CYP450 2B6, 2C9 and 2C19 genes and the pre transplant hepatic status (Lucarelli class) of the patient. All patients received Cy at a dose of 50mg/kg as one-hour intravenous infusion for 4 days (day -5 to -2) after 4 days of busulfan (day-9 to -6). Levels of Cy and 4-HCy were measured using high performance liquid chromatography. Genotyping for CYP2B6 G516T, CYP2C9 *2, *3 and CYP2C19*2 and *3 were done using PCR-RFLP methods. There was a 4–20 fold inter-patient variation in the PK of Cy and 4-HCy. Mean AUC of Cy was 2288±1169 mg* h/ml, (range: 674–5126), while that of AUC of 4-HCy was 5.67±2.52 mg* h/ml (range: 0.817–11.17). Patients with wild type CYP2B6 G/G genotype had significantly higher Cy 4-hydroxylation than those with the homozygous mutant genotype (T/T). CYP4502B6, 2C9, 2C19 genotypes and ratio of AUC 4HCy/AUC Cy CYP2B6 G/G (n=15) G/T (n=8) T/T (n=16) t-test p value 0.0033±0.0014 0.003±0.0013 0.0023±0.0011 0.03 (G/G vs. T/T) CYP2C9 *1/*1 (n=25) *1/*2 (n=3) *1/*3 (n=9) *2/*3 (n=2) *3/*3 (n=1) 0.003±0.0016 0.0037±0.0009 0.0023±0.0011 0.0014, 0.0015 0.0073 0.076 (*1/*2 vs. *1/*3) CYP2C19 *1/*1 (n=26) *1/*2 (n=10) *2/*2 (n=3) 0.0026±0.001 0.0036±0.0012 0.0029±0.0013 0.016 (1/1 vs. 1/2) One patient with homozygous mutant genotype CYP 2C9 3/3 showed 2.6 fold higher Cy 4-hydroxylation (0.0073 vs. 0.0026), while two patients with CYP2C9 2/3 genotype had 2 fold lower than the mean of the ratio for all 2C9 genotypes. Patients with CYP2C19 1/2 genotype showed significantly higher ratio than those with CYP2C19 1/1 genotype. No association was found between patients’ pre- transplant liver status (Lucarelli class) and Cy 4-hydroxylation. We conclude that 4-hydroxylation of Cy is significantly influenced by CYP2B6, 2C9 and 2C19 genotypes. This could explain the wide inter individual variation in Cy PK which should be correlated with toxicity and outcome of BMT.

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