Hematopoietic stem cell transplantation for homozygous ß-thalassemia and ß-thalassemia/hemoglobin E patients from haploidentical donors.

Thalassemia-free survival after allogeneic stem cell transplantation (SCT) is about 80-90% with either matched-related or -unrelated donors. We explored the use of a mismatched-related ('haplo- ') donor. All patients received two courses of pretransplant immunosuppressive therapy (PTIS) with fludarabine (Flu) and dexamethasone (Dxm). After two courses of PTIS, a conditioning regimen of rabbit antithymocyte globulin, Flu and IV busulfan (Bu) was given followed by T-cell-replete peripheral blood progenitor cells. GvHD prophylaxis consisted of cyclophosphamide (Cy) on days SCT +3 and +4 (post-Cy), and on day SCT +5 tacrolimus or sirolimus was started together with a short course of mycophenolate mofetil. Thirty-one patients underwent haplo-SCT. Their median age was 10 years (range, 2-20 years). Twenty-nine patients engrafted with 100% donor chimerism. Two patients suffered primary graft failure. Median time to neutrophil engraftment was 14 days (range, 11-18 days). Five patients developed mild to moderate, reversible veno-occlusive disease, while nine patients developed acute GvHD grade II. Only five patients developed limited-chronic GvHD. Projected overall and event-free survival rates at 2 years are 95% and 94%, respectively. The median follow up time is 12 months (range, 7-33 months).

Immunogenicity of a live-attenuated Japanese encephalitis vaccine in children and adolescents after hematopoietic stem cell transplantation.

There have been no recommendations for revaccination with the Japanese encephalitis (JE) vaccine in post-hematopoietic stem cell transplantation (HSCT) patients. This study aimed to measure the immunogenic response to a live-attenuated JE vaccine (SA 14-14-2) in post-HSCT patients. JE-specific neutralizing Ab titers were measured before and after the JE vaccination. The patients with Ab titers <10 at the 3-month time point received a second injection at 6 months. A total of 28 patients (male:female=11:17) with a median age of 13 years (4-21 years) were included. The underlying diseases were thalassemia (50%) and hematologic malignancies (50%). Ten patients (35.7%) had Ab titers above the preventive level before vaccination. Nine of 18 patients (50%) seroconverted at 3 months after a single JE vaccination, but only three of these patients had sustained protective Ab levels. Seven of nine patients (78%) seroconverted at 3 months after a second JE vaccine injection, and all of these patients sustained protective Ab levels at 12 months. In conclusion, post-HSCT patients had low seroconversion rates after a single dose of the live-attenuated JE vaccine. These patients may require at least two doses of the JE vaccine to ensure protective Ab levels.

Interphase-FISH screening for eight common rearrangements in pediatric B-cell precursor acute lymphoblastic leukemia.

INTRODUCTION: This is the first pilot study to screen multiple common genetic aberrations in B-cell precursor acute lymphoblastic leukemia (BCP-ALL). METHODS: Thirty-two children with BCP-ALL were investigated for chromosomal rearrangements using interphase fluorescence in situ hybridization (FISH). Eight common translocations and rearrangements, including ETV6-RUNX1, TCF3-PBX1, BCR-ABL1, ETV6, TCF3, MLL, IGH@, and PAX5, were tested for using dual-color DNA probes. RESULTS: ETV6-RUNX1 was the most frequent translocation detected in 11 children (34.4%). Two patients with BCR-ABL1 (6.3%) and one with TCF3-PBX1 (3.1%) translocations were also observed. Using break-apart probes, 11 children (34.4%) had a positive FISH result for ETV6, two patients for IGH@ (6.3%), one patient for MLL (3.1%), and one patient for PAX5 rearrangements (3.1%). All patients with the ETV6-RUNX1 fusion were also identified by split signals for ETV6. Other abnormalities, including extra copies and deletion of genes, were observed within the range of 3.1-34.4%. Cytogenetics analysis showed a single case each of BCR-ABL1 fusion, MLL, and IGH@ rearrangements (3.1% each). ETV6-RUNX1 fusion and ETV6 split-apart rearrangements were not visible by cytogenetics. Likewise, one each of cases with TCF3-PBX1 fusion and with PAX5 split signal seen by FISH was not visible by cytogenetics. CONCLUSION: By using 8 FISH probes in conjunction cytogenetics for the detection of common aberrations, interphase FISH enhanced the detection of chromosomal rearrangements in children with BCP-ALL.

Polymorphism of glutathione S-transferase Omega gene: association with risk of childhood acute lymphoblastic leukemia.

PURPOSE: To evaluate the association between glutathione S-transferase Omega (GSTO) genes polymorphism and the susceptibility of acute lymphoblast leukemia (ALL). METHODS: The polymorphism of GSTO1 and GSTO2 genes were analyzed in 99 ALL patients compared with 100 healthy children by PCR-based restriction fragment length polymorphism (RFLP) analysis. RESULTS: GSTO1*A140D polymorphism was significantly associated with susceptibility to ALL (OR = 2.24, 95% CI = 1.16-4.35, P = 0.009) whereas, GSTO2*N142D genotype was significantly interacted with high risk group of childhood ALL (OR = 5.52, 95% CI = 1.72-17.71, P = 0.004). CONCLUSION: This study revealed gene polymorphism in glutathione S-transferase Omega class may be a risk factor to the development of acute childhood lymphoblastic leukemia.

Simple multiplex RT-PCR for identifying common fusion transcripts in childhood acute leukemia.

Nonrandom gene rearrangements have been demonstrated in leukemic cells at diagnosis. These genetic abnormalities are associated with specific types, clinical characteristics, and prognosis of acute leukemia. Common fusion transcripts in childhood acute lymphoblastic leukemia (ALL) are TEL-AML1, E2A-PBX, MLL-AF4, and BCR-ABL (p190) and in acute nonlymphoblastic leukemia (ANLL) are AML-ETO, PML-RARA, and CBFB-MYH11. Reverse transcription-polymerase chain reaction (RT-PCR) for detection of each individual fusion transcript is impractical and time consuming. The purpose of this study was to develop simple RT-PCR methods to identify common fusion transcripts of newly diagnosed acute leukemia in children. Total RNA was extracted from bone marrow samples of children diagnosed with acute leukemia. Multiplex RT-PCR panel A (ALL) included primers for TEL-AML1, E2A-PBX, MLL-AF4, and BCR-ABL (p190) whereas panel B (ANLL) composed of primers for AML-ETO, PML-RARA, and CBFB-MYH11. Known leukemic cell lines were used to serve as positive controls. Eighty three children diagnosed with ALL (n = 63) and ANLL (n = 20) were included in this study. Fusion transcripts could be identified using multiplex RT-PCR panel A for ALL and panel B for ANLL in 26/83 (31.3%) cases. In ALL samples, we found TEL-AML1 = 16/63 (25.4%), E2A-PBX = 3/63 (4.8%), MLL-AF4 = 1/63 (1.6%), and BCR-ABL = 1/63 (1.6%). Four cases of AML1-ETO (20%) and one PML-RARA (5%) were found in ANLL samples. In conclusion, our simple multiplex RT-PCR for detection of fusion transcripts in childhood acute leukemia was found to be a rapid, accurate, and effective method.

Rituximab as an adjuvant therapy to immune tolerance in a haemophilia A boy with high inhibitor titre.

We report a haemophilia A boy with high inhibitor titre (170 BU) who experienced five life-threatening bleeding episodes during a one-year period from 9 to 21 months. At the age of 22 months, he received rituximab (375 mg m(-2) per dose) at one- and three-week intervals, three courses each and alternative daily treatment with factor VIII concentrate at doses of 100 units kg(-1) for 24 weeks and 50 units kg(-1) for the following 28 weeks. Although the pretreatment inhibitor level of 4.5 BU showed an anamnestic response reaching the maximum level of 200 BU at the 9th week of treatment, it gradually declined to 30 BU at the 22nd week and was constantly maintained at 25-30 BU for the following 30 weeks. Only three bleeding episodes of two haematomas and one haemarthrosis were found during the one-year treatment period. No opportunistic infection occured during this period.

Polymorphisms of drug-metabolizing enzymes and risk of childhood acute lymphoblastic leukemia.

The involvement of phase I and II enzymes is well documented in the metabolism of a wide range of drugs and xenobiotics. Single-nucleotide polymorphisms (SNPs) of these enzymes are also known to alter their protein expression and function. Moreover, genetic susceptibility and environmental exposure have been proposed to be an etiology of cancer. We hypothesized that polymorphisms of these enzymes might affect the risk of childhood acute lymphoblastic leukemia (ALL). CYP 1A1, CYP 3A4*1B, CYP 3A5*3, CYP 3A5*6, GSTM1, and GSTT1 polymorphisms were genotyped by using PCR-RFLP in 107 children with ALL and 320 healthy controls. Allele and genotype frequencies of each of the SNPs were compared between two groups. It was found that the allele frequencies of CYP 1A1*1, *2A, *2B, and *4 were not different between cases and controls. CYP 3A4*1B allele frequency was only 0.8% and 0.9% in ALL and controls, respectively. CYP 3A5*1/*1, *1/*3, and *3/*3 genotype frequencies showed no statistically significant difference between patients and controls. CYP 3A5*6 was not detected in our population. The GSTM1 null genotype was significantly increased in children with ALL (OR 1.7; 95% CI, 1.0, 2.7). In contrast, the GSTT1 null genotype did not show this effect. Our data thus demonstrate that the GSTM1 null genotype might increase the risk of childhood ALL in a Thai population.

Outcome of transplantation with unrelated donor bone marrow in children with severe thalassaemia.

SUMMARY: We conducted a study of unrelated donor bone marrow transplantation (BMT) in 11 children with severe thalassaemia. The conditioning regimen consisted of busulphan, cyclophosphamide and antilymphocyte globulin. All received T-cell nondepleted bone marrow. The median marrow-nucleated cell dose was 4.9 x 10(8) /kg (range; 3.5-8.0 x 10(8) /kg). Median time of granulocyte recovery was 16 days (range; 13-21 days), and of platelet recovery was 39 days (range; 14-196). Grade 2-4 acute graft-versus-host disease (GVHD) developed in six patients (54%), and grade 3-4 in one patient (9%). Three (27%) of 11 evaluable patients had chronic GVHD (limited stage). All 11 patients are alive without thalassaemia after a median follow-up time of 397 days (range; 171-814 days). This study lends support to consideration of unrelated donor BMT as an acceptable therapy to cure severe thalassaemia especially in patients who are young and do not yet show irreversible severe complications of iron overload.

The usefulness of X-linked polymorphic loci as gene markers to track X allele and chimerism in a post-allogeneic peripheral blood stem cell transplant patient with Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS), an X-linked recessive disorder, is characterized by progressive T-cell immunodeficiency. Laboratory findings generally demonstrate reduced response to T-cell mitogens, markedly decreased serum concentration of IgM, and thrombocytopenia with small platelet volume. Allogeneic HLA-matched sibling bone marrow transplantation (BMT) can correct this disorder. We report the usefulness of X-linked polymorphic loci to detect X-allele gene tracking among WAS siblings and chimerism between a pre- and post-allogeneic matched sibling peripheral blood stem cell transplantation (PBSCT). A 3 1/2 year old boy with clinical and laboratory findings consistent with WAS underwent allogeneic matched sibling PBSCT. We used BclI restriction fragment length polymorphism (RFLP) of intron 18 of factor VII gene and MseI RFLP of the 5' flanking region of factor IX gene to detect X-allele gene tracking among siblings and family members and chimerism in patients between pre-and post-allogeneic matched sibling PBSCT. We were able to demonstrate that determination of BclI and MseI RFLP can be employed to recognize the difference in X-allele genes between the recipient and donor for allogeneic matched sibling PBSCT. The authors also were able to demonstrate that these polymorphic loci can detect full chimerism of donor hematopoietic cells in recipient blood after allogeneic PBSCT. This finding was correlated with improvement of post-PBSCT clinical and laboratory findings. BclI and MseI RFLP associated with X-chromosome can effectively track X-allele, detect carrier state, and demonstrate the different X-allele among male siblings, and chimerism of hematopoietic cells between donors and recipients in a setting of allogeneic matched sibling BMT or PBSCT for X-linked hereditary diseases such as Wiskott-Aldrich syndrome.

Frequency of thiopurine S-methyltransferase genetic variation in Thai children with acute leukemia.

BACKGROUND: Thiopurine S-methyltransferase (TPMT) catalyzes the S-methylation (inactivation) of mercaptopurine, azathioprine, and thioguanine, and exhibits genetic variation. About 11% of Caucasians have intermediate TPMT activity because of heterozygosity, and about 1 in 300 inherits TPMT deficiency as an autosomal codominant trait. If patients who have intermediate or deficient TPMT activity receive the standard dose of thiopurine medications, they can accumulate excessive thiopurine nucleotides in hematopoietic tissue, which could lead to severe and possibly fatal myelosuppression. There is very little information about TPMT genetic variation among Asian populations. We investigated the frequency of TPMT genetic variation among Thai children with acute leukemia. PROCEDURE: Fresh whole blood was obtained from 75 Thai children with acute leukemia at the time of remission. Genomic DNA was isolated from total peripheral white blood cells. We performed polymerase chain reaction (PCR) to detect 3 types of variant of the human TPMT gene. RESULTS: Among 75 patients, the frequency of heterozygotes for the TPMT gene among Thai children with acute leukemia was approximately 11%. However, the TPMT*3C was the only variant TPMT allele found among Thai children. This is different from the North American Caucasian populations, in which TPMT*3A is the predominant variant allele, and TPMT*3C is rare (approximately 5% of variant alleles). CONCLUSIONS: There is no difference in the frequency of this genetic variation between Asian and North American Caucasian populations. Determination of the TPMT genotype by PCR method before antileukemic therapy is practical and may have clinical relevance. This knowledge could be applied towards organ transplant recipients who require these medications for immunosuppression.

Immune tolerance in a haemophilia A patient with high inhibitor using locally prepared lyophilized cryoprecipitate.

The immune tolerance in a 12-year-old haemophilia A patient was carried out at the Faculty of Medicine, Ramathibodi Hospital, Bangkok in 1998. His inhibitor titres ranged from 10 to 3450 Bethesda units (BU). He suffered from serious bleeding episodes requiring prolonged hospitalization and the disarticulation of the left knee joint. After obtaining informed consent, locally prepared lyophilized cryoprecipitate (LC), heat treated at 60 degrees C for 25 h, was given in a dose of 13 units kg-1 body weight of factor VIII three times per week. His inhibitor was increased from 15 to 580 BU within the first 4 weeks of immune tolerance. Finally, it was decreased to 40 BU in the 36th week. The only adverse effect was seroconversion of anti-hepatitis C virus after receiving 108 bottles of LC for 36 weeks. In conclusion, the locally prepared LC was able to control the bleeding episodes in a haemophilia A patient with high inhibitor. To our knowledge, this is the first reported case in Thailand.

Extramedullary haematopoietic tumor producing small intestinal intussusception in a beta-thalassemia/hemoglobin E Thai boy: a case report.

The authors report a case of beta-thalassemia/hemoglobin E disease with extramedullary haematopoietic tumor which developed at the small intestine and caused intussusception. A 7 year-old boy with homozygous beta-thalassemia/hemoglobin E presented with recurrent abdominal pain. The abdominal ultrasonography showed ileo-ileal intussusception with a solid mass as the leading point. Resection of the ileal segment was performed. Pathological examination revealed an extramedullary haematopoietic tumor forming an intraluminal polypoid mass, being the leading point of the intussusception. Extramedullary haematopoiesis in the intestinal tract is rare. To our knowledge, this is the first case of extramedullary haematopoietic tumor that produced intussusception of the small intestine in a beta-thalassemia/hemoglobin E patient.