Disposition of oral methotrexate in children with acute lymphoblastic leukemia and its relation to 6-mercaptopurine pharmacokinetics

We studied the disposition pharmacokinetics of methotrexate (MTX) given orally to 16 children with acute lymphoblastic leukemia (ALL) and its relation to the pharmacokinetics of 6-mercaptopurine (6MP) in the same children. There was an eightfold variability in area-under-concentration time-curve (AUC) of MTX achieved by the same dose. Excellent correlation existed between peak concentrations and AUC0----infinity (r = 0.95, P less than 0.001). Elimination T1/2 was between 1.34 and 5 hours (mean 2.16 +/- 0.23 hr, mean +/- SE). A weak correlation existed between AUC achieved by 1 mg/m2 MTX and patients' age or body weight. Weak but significant correlation existed between AUC achieved by 1 mg/m2 of MTX vs. 6MP (r = 0.54, P less than 0.05). In 13/16 patients peak concentrations were achieved at 60 minutes. There was a significantly larger AUC of 6MP achieved by a standardized dose in longer therapy (greater than 15 mo) vs. short therapy (less than 12 mo) (462 +/- 75 and 246 +/- 58 ng.ml-1.min.mg-1.m2, P less than 0.025). No statistical differences in AUC of MTX were found between short and long therapy. The large interpatient variability in MTX pharmacokinetics supports the possibility that differences in absorption and/or clearance of the drug may affect the clinical response. Because of the excellent correlation between peak and AUC of MTX, and because 3 measurements, at 30, 60, and 90 minutes will almost invariably identify the peak, this measurement can be used to estimate AUC for purpose of correlation with clinical outcome.

Transfusion-dependent congenital dyserythropoietic anemia type I successfully treated with allogeneic stem cell transplantation

Until recently, therapy for patients with severe congenital dyserythropoietic anemia (CDA) has been limited to blood transfusions and chelation therapy. Three children with transfusion-dependent CDA type I underwent allogeneic stem cell transplantation (SCT) from matched sibling donors. Conditioning was with cyclophosphamide 50 mg/kg/day for 4 days, busulphan 4 mg/kg/day for 4 days, and antithymocyte globulin (ATG) 30 mg/kg for four doses pre-SCT. All patients engrafted and are alive, and transfusion independent. To our knowledge, this is the first report of successful SCT in the management of CDA type I.

Congenital sideroblastic anaemia successfully treated using allogeneic stem cell transplantation

Therapy for patients with congenital sideroblastic anaemia has been limited to blood transfusions and chelation. Three children with congenital sideroblastic anaemia (SA) who were blood transfusion dependent underwent stem cell transplantation (SCT) from matched sibling donors. Conditioning consisted of cyclophosphamide 50 mg/kg/d for 4 d, busulphan 4 mg/kg/d for 4 d and anti-thymocyte globulin (ATG) 30 mg/kg for four doses pretransplant. Graft-versus-host disease (GVHD) prophylaxis was with cyclosporin A and methotrexate. All patients engrafted, and are alive and transfusion independent. SCT can be curative for patients with SA.

Bone marrow transplantation from matched siblings in patients with fanconi anemia utilizing low-dose cyclophosphamide, thoracoabdominal radiation and antithymocyte globulin

Nineteen patients with Fanconi anemia (FA) and bone marrow failure underwent bone marrow transplantation (BMT) from matched siblings. Median age at BMT was 8.7 years. Conditioning consisted of low-dose cyclophosphamide (CY 5 mg/kg x 4 days) and thoracoabdominal irradiation (TAI 400 cGy). Graft-versus-host disease (GVHD) prophylaxis was cyclosporin A (CsA) in 13 patients and CsA plus methotrexate in 6 patients. Antithymocyte globulin (ATG) was added in the pretransplant as well as the post-transplant period. All patients received high-dose acyclovir from day 2 pre-BMT to day 28 post BMT, and intravenous immunoglobulins (IVIG), 500 mg/kg weekly from day 7 pre-BMT to day 90 post BMT. No fungal prophylaxis was given. All patients engrafted, (median, 14 days for an absolute neutrophil count > or =0.5 x 10(9)/l; median, 37 days for platelet count > or =20 x 10(9)/l). Fourteen (74%) patients are alive with sustained engraftment and are transfusion independent. Three (16.6%) patients developed acute GVHD; none developed chronic GVHD. Five (26%) patients developed invasive fungal infections, and two (10%) developed fatal CMV disease. We believe the addition of ATG may have contributed to the increased incidence of severe life-threatening fungal and viral infections in our series.

Thiamine-responsive myelodysplasia

The triad of thiamine-responsive anaemia, diabetes mellitus and deafness has been reported in 15 patients with macrocytic anaemia, sometimes associated with moderate thrombocytopenia. The bone marrow aspirate usually shows megaloblastic changes and ringed sideroblasts. However, tri-lineage myelodysplasia has never been reported. We describe two patients who presented with diabetes, deafness and thiamine-responsive pancytopenia. Bone marrow aspirate and biopsy were typical of tri-lineage myelodysplasia. These findings suggest that thiamine may have a role in the regulation of haemopoiesis at the stem cell level. We propose the term 'thiamine-responsive myelodysplasia' rather than that of thiamine-responsive anaemia.

Engraftment failure following bone marrow transplantation in children with thalassemia major using busulfan and cyclophosphamide conditioning

Thirteen children older than 3 years of age with beta-thalassemia major underwent allogeneic bone marrow transplantation (BMT) from a full human leukocyte antigen (HLA) matched sibling donor in a single institution. These patients received busulfan (Bu). 16 mg/kg followed by cyclophosphamide (Cy) 200 mg/kg for conditioning. Eight of the 13 patients (Group 1) engrafted and have a median age of 13 years (range 5-15 years). The five patients (Group 2) who failed to engraft have a median age of 6 years (range 3-8 years). The association with the following factors was found to be statistically significant: age (older in Group 1), duration of nadir of white blood count (WBC) of < or = .1 x 10(9)/L (longer in Group 1), and the dose of Bu administered to each patient calculated on the basis of body surface area (higher dose in Group 1). The high rate of engraftment failure (5 out of 13) may be related to the suboptimal systemic exposure of Bu in younger children leading to inadequate bone marrow ablation when the standard dose of 16 mg/kg is used.

Bone marrow transplantation in patients with Fanconi anemia: experience with cyclophosphamide and total body irradiation conditioning regimen

Eleven patients with Fanconi anemia (FA) underwent bone marrow transplantation (BMT) between March 1985 and May 1990 in a single institution. Ten patients received bone marrow from healthy full human leukocyte antigen (HLA) matched siblings and one patient from her father (one antigen mismatch). Ten patients were conditioned with cyclophosphamide (Cy) at a dose of 5 mg/kg per day for 4 days followed by total body irradiation (TBI) for a total of 600 cGy over 3 days. Six of the 11 patients are alive and have normal reconstitution of their bone marrow. Median follow-up was 72 months (range 42-84). Three of the 10 patients who received Cy and TBI (two HLA compatible, one antigen mismatch) had graft failure. Five patients developed at least grade III acute graft-versus-host disease (GVHD). The rates of graft failure and GVHD are, however, still significantly high. Modification of the conditioning regimen and GVHD prophylaxis is needed to improve the outcome.

Pediatric cancer: The King Faisal Specialist Hospital and Research Centre experience

Between January 1976 and December 1993, a total of 3291 children with cancer were treated at King Faisal Specialist Hospital and Research Centre (KFSH&RC). Males accounted for 60.7% and females 39.3%, with a ratio of 1.5:1. The peak age was two to five. The three most common malignancies were leukemias (26.2%), lymphomas (21.3%), and central nervous system (CNS) tumors (15.3%). This report presents some of the epidemiologic data related to the largest number of children with malignancy treated in a single institution in Saudi Arabia.

Bone marrow transplantation for infantile malignant osteopetrosis

PURPOSE

Most patients diagnosed with malignant osteopetrosis die during infancy or early childhood from hemorrhage and infection due to bone marrow failure. Allogeneic bone marrow transplantation (BMT) has been reported to provide curative therapy for this disorder. We report our experience with eight patients with malignant osteopetrosis who underwent BMT.

PATIENTS AND METHODS

Between May 1987 and August 1992, eight children with malignant osteopetrosis underwent allogeneic BMT. Median age at BMT was 9 months (range, 2-36 months). Six patients received marrow from HLA-identical sibling donors, one from phenotypically matched father, and one from a one antigen mismatched father. BMT conditioning for all patients was busulfan 16 mg/kg and cyclophosphamide 200 mg/kg each administered over 4 days. Graft versus host disease (GVHD) prophylaxis included cyclosporin A in six patients or cyclosporin A and methotrexate in two patients.

RESULTS

Six patients, including those who received bone marrow from their father's, engrafted as documented by bone marrow biopsy showing an increase in osteoclasts in all cases and by chromosomal analysis in four patients. Two patients died without engraftment. Three out of six patients engrafted are alive and well at the follow-up of 48, 63, and 81 months. Serum calcium, alkaline, and acid phosphatase levels normalized within 2 months. These patients have full bone marrow reconstitution. Serial radiologic studies revealed bone marrow remodelling and a new nonsclerotic bone formation. Vision improved dramatically in the youngest patient.

CONCLUSION

BMT offers cure to patients with malignant osteopetrosis with reconstitution of bone marrow and correction of metabolic disturbances. In our experience, reversibility in neurosensory deficit is possible when BMT is done at an early age.

Hematopoietic progenitor cells are resistant to dimethyl sulfoxide toxicity

BACKGROUND

A direct chemical toxicity of dimethyl sulfoxide (DMSO) to hematopoietic progenitor cells has been suggested. However, a recent study failed to corroborate these earlier findings. Thus, a series of experiments was undertaken to address this issue.

STUDY DESIGN AND METHODS

Bone marrow was collected from 18 donors and cryopreserved with 10 percent (vol/vol) DMSO. Aliquots of frozen bone marrow were thawed, diluted with ACD-A to 8 percent (vol/vol) DMSO, and allowed to remain in DMSO for up to 2 hours before mononuclear cells were plated for colony-forming assays. After 14 days in culture, burst-forming units-erythroid, colony-forming units--granulocyte/macrophage, and colony-forming units--granulocyte/erythrocyte/macrophage/megakaryocyte colonies were enumerated.

RESULTS

There was no significant difference (p > 0.5) seen in colony formation over the 2-hour exposure to DMSO.

CONCLUSION

These results support and extend a previous study that bone marrow hematopoietic progenitor cells, including burst-forming units--erythroid, colony-forming units--granulocyte/macrophage, and colony-forming units--granulocyte/erythrocyte/macrophage/megakaryocyte are resistant to any toxic effects of 8- to 10-percent (vol/vol) DMSO during at least 2 hours of DMSO exposure.

A regional autologous bone marrow transplant network: transfers to designated centers on the day after transplant

Autologous bone marrow transplantation (ABMT) is becoming increasingly prevalent for treatment of advanced malignant disease. In order to increase the availability and utility of this therapy, we assessed the feasibility of transferring patients to their regional referral centers on the day after marrow infusion (day 1), for management post-transplant. This prospective study compares the outcome of 77 patients either transferred the day after marrow transplant for subsequent management at one of six selected Canadian regional centers closest to their domicile, or treated entirely at The Toronto Hospital, according to a common protocol. Study end-points included frequency of complications during transfer, transplant-related morbidity and mortality and hematopoietic recovery. Assessment of eligibility for transplant, bone marrow harvesting, autograft cryopreservation, administration of intensive therapy and marrow infusion were conducted in all cases at The Toronto Hospital. Thirty patients received marrow transplants and were transferred on day 1. There were no complications during transfer. Compared with 47 consecutive patients treated entirely at The Toronto Hospital, there were no differences in treatment-related morbidity or mortality, use of intravenous antifungal therapy or total days of hospitalization. We conclude that day 1 transfer of patients after ABMT to designated centers is feasible and safe. The operation of a regional ABMT network appears to benefit patients, relatives, referring physicians, the transplant center and may also improve health care delivery.

Secondary acute non-lymphocytic leukemia with monosomy 7 arising 9 years after acute lymphoblastic leukemia in childhood

We report a case of pediatric acute non-lymphocytic leukemia (ANLL) with monosomy 7 occurring in a child successfully treated for acute lymphoblastic leukemia (ALL) nine years earlier. Acquired monosomy 7 is currently recognized as a distinct therapy-related cytogenetic abnormality which nonrandomly occurs as a late complication of cytotoxic therapy used in the treatment of both malignant and nonmalignant disease. Most commonly, this occurs as a disorder of bone marrow morphology and function characterized as a myelodysplastic syndrome (MDS) or ANLL. This case report emphasizes the need for continued evaluation of long-term survivors of childhood cancer to identify and minimize therapy-related side effects without compromising successful management.

T-cell lymphoma and mature nephroblastoma after synchronous bilateral Wilms' tumor

A 15-year-old boy had lymphoblastic lymphoma of the left tonsil after being treated for bilateral Wilms' tumor (BWT) at 7 months of age. In addition, a fully differentiated Wilms' tumor was diagnosed in the remaining, partially nephrectomized left kidney. Development of second malignancies in patients with a history of BWT, as compared with those with unilateral Wilms' tumor, is discussed. A possible explanation for the concurrently diagnosed, fully differentiated Wilms' tumor in the remaining left kidney is suggested.

Neuroblastoma stage IV-S: a heterogeneous disease

Eighteen patients were diagnosed and treated for Stage IV-S neuroblastoma at The Hospital for Sick Children, Toronto between January 1971 and December 1988. All patients were 6 months of age or younger at diagnosis. Nine patients (50%) have remained disease free with a mean follow-up of 9.3 years. Of the seven patients under 6 weeks of age at presentation, four presented in the early neonatal period and died, three due to mechanical complications related to progressive disease, and one due to late recurrence. The remaining three patients under 6 weeks of age, two of whom had skin involvement at diagnosis, are alive and disease free. Six of the 11 patients over 6 weeks of age at presentation survived, combined modality therapy (CMT) being more effective than single modality treatment. N-myc was studied from tumor tissue at diagnosis in four patients and was amplified in three (25x, 25x, 100x), all of whom had late disease progression and died. The patient with a single gene copy has no evidence of disease 24 months following diagnosis. Our study confirms the heterogeneity described in this clinically defined group of patients. Because of it, management of Stage IV-S neuroblastoma cannot be uniform and until further development of a subclassification, or a reclassification based on molecular biologic markers is developed, pediatric oncologists will regularly be confronted with a decision whether or not to treat a newly presenting patient that fits into the clinical classification IV-S.