Estimating the effect of lung collapse and pulmonary shunt on gas exchange during breath-hold diving: the Scholander and Kooyman legacy.

We developed a mathematical model to investigate the effect of lung compression and collapse (pulmonary shunt) on the uptake and removal of O(2), CO(2) and N(2) in blood and tissue of breath-hold diving mammals. We investigated the consequences of pressure (diving depth) and respiratory volume on pulmonary shunt and gas exchange as pressure compressed the alveoli. The model showed good agreement with previous studies of measured arterial O(2) tensions (Pa(O)(2)) from freely diving Weddell seals and measured arterial and venous N(2) tensions from captive elephant seals compressed in a hyperbaric chamber. Pulmonary compression resulted in a rapid spike in Pa(O)(2) and arterial CO(2) tension, followed by cyclical variation with a periodicity determined by Q(tot). The model showed that changes in diving lung volume are an efficient behavioural means to adjust the extent of gas exchange with depth. Differing models of lung compression and collapse depth caused major differences in blood and tissue N(2) estimates. Our integrated modelling approach contradicted predictions from simple models, and emphasised the complex nature of physiological interactions between circulation, lung compression and gas exchange. Overall, our work suggests the need for caution in interpretation of previous model results based on assumed collapse depths and all-or-nothing lung collapse models.

Sequence conservation in the rRNA first internal transcribed spacer region of Babesia gibsoni genotype Asia isolates.

Babesia gibsoni genotype Asia is a small, tick-transmitted intraerythrocytic protozoan that parasitizes dogs. Reports suggest that it is increasingly diagnosed in the United States. The clinical outcome of infection with this piroplasm is often variable, leading us to hypothesize that the different clinical outcomes resulting from B. gibsoni genotype Asia infection are due to genetically distinguishable strains that differ in virulence. As a first step to assess the genetic variability of B. gibsoni isolates originating from the southeastern United States, we sequenced the rRNA first internal transcribed spacer region of recent isolates from Georgia and Alabama, and compared these sequences with isolates originating from Japan and Australia. All isolates examined proved to be genetically identical at the first internal transcribed spacer region, although this region differed distinctly from other Babesia species and closely related apicomplexan species. Although negating our hypothesis, this information gives us insight into the recent evolutionary history and spread of B. gibsoni genotype Asia in dogs in the U.S. Our research suggests that the gradual rise in prevalence of canine babesiosis due to B. gibsoni genotype Asia in the United States may be a result of clonal expansion of a single strain within a susceptible host population.

Inhibitory effect of adenosine dialdehyde on in situ murine neuroblastoma growth.

The effect of adenosine dialdehyde (AD) on in situ tumor growth and host survival was evaluated in the C1300 murine neuroblastoma tumor model prepared by implantation of murine neuroblastoma cells into A/J mice. AD was administered s.c. by one of the following treatment regimens: regimen A, single daily dose for 5 days; regimen B, minipump infusion for 7 days; regimen C, minipump infusion for 14 days; regimen D, minipump infusion for two 7-day periods interspersed by a 7-day drug free interval. AD doses of 1.5 to 2.5 mg/kg/day infused over a 7-day period (regimen B) significantly increased the mean life span of tumor bearing mice from 20.9 +/- 1.2 days (mean +/- 2 SEM) in diluent treated controls to 35.3 +/- 2.1 days in AD treated animals (mean increase +/- 2 SEM: 69 +/- 10%; P less than 0.0001). This treatment regimen also produced a 56 +/- 13% decrease in tumor diameter (P less than 0.0001). Administration of AD for two 7-day infusion periods, interspersed by a 7-day drug free interval (regimen D), increased mean life span 80% (controls, 21.3 +/- 4.4 days; AD treated 38.4 +/- 5.6 days; P less than 0.0005). Hematopoietic toxicity was not observed when doses between 2 and 3 mg/kg/day of AD were infused for 7 days (regimen B). These data suggest that steady state infusions of AD can significantly suppress murine neuroblastoma tumor growth with little systemic toxicity. In contrast, single daily injections of AD were ineffective and toxic to the tumor bearing host.

Elevation of cerebrospinal fluid catecholamine metabolites in patients with intracranial tumors of neuroectodermal origin.

The concentrations of homovanillic acid (HVA), hydroxymethoxyphenylethyleneglycol (HMPG), and vanillylmandelic acid (VMA) were determined in lumbar cerebrospinal fluid (CSF) specimens. The study population consisted of the following groups: control subjects with malignancies of nonneuroectodermal origin (mostly leukemia in remission), neuroblastoma (extracranial and intracranial or cranial metastases), brain tumors (neuroectodermal and glial), and retinoblastoma. A significant increase in the CSF concentration of HVA was observed in patients with brain tumors (neuroectodermal), neuroblastoma (intracranial or cranial metastases), and retinoblastoma when compared with age-matched controls. In contrast, HMPG and VMA concentrations did not differ from controls except in patients with neuroblastoma (intracranial or cranial metastases) and brain tumors (neuroectodermal) who had significant elevations in HMPG and VMA, respectively. An inverse correlation was noted between the CSF concentration of HVA and clinical response to therapy. Nonresponding patients exhibited increases in HVA when compared with pretreatment values. These data suggest that the quantitative determination of catecholamine metabolites in lumbar CSF is an effective method for diagnosing intracranial tumors of neuroectodermal origin and assessing their response to therapy.

Successful reinduction of patients with acute lymphoblastic leukemia who relapse following bone marrow transplantation.

At the present time, there is limited information on the outcome of patients with acute lymphoblastic leukemia (ALL) who relapse after bone marrow transplantation (BMT). Intuitively, it might be expected that leukemia recurring after BMT would be refractory to further treatment. In an attempt to improve survival in patients with ALL who relapse after BMT, we used standard chemotherapy for reinduction and maintenance. Of 65 patients who relapsed following allogeneic, autologous, or syngeneic BMT, 12 elected to receive no further chemotherapy, and their median survival from relapse was 36 days (range 13 to 167 days). The 53 patients who received therapy had a significantly longer median survival of 168 days (range 18 days to 4.7 years). With multidrug induction regimens there were 29 of 52 (56%) complete remissions. Six patients are currently alive, with two off therapy. In the patients who received therapy, the following factors were independent predictors of prolonged survival: longer time from BMT to relapse; younger age at diagnosis; and the use of a preparative regimen containing fractionated total body irradiation. In conclusion, leukemia recurring after BMT remains sensitive to standard therapy in many patients. We recommend that patients with ALL who relapse after BMT receive reinduction and maintenance therapy as additional good quality survival time is achieved in patients who attain a remission.

Clinical features and treatment outcome of childhood T-lineage acute lymphoblastic leukemia according to the apparent maturational stage of T-lineage leukemic blasts: a Children's Cancer Group study.

PURPOSE: Leukemic cells from T-lineage acute lymphoblastic leukemia (ALL) patients are thought to originate from T-lymphocyte precursors corresponding to discrete stages of T-cell ontogeny. Here we sought to determine the influence of leukemic cell apparent maturational stage on treatment outcomes in pediatric T-lineage ALL. PATIENTS AND METHODS: From 1983 through 1993, 407 pediatric T-lineage ALL patients were enrolled onto two sequential series of risk-adjusted treatment protocols of the Children's Cancer Group. In the current analysis, T-lineage ALL patients were immunophenotypically classified as follows: CD7+ CD2- CD5- pro-thymocyte leukemia (pro-TL), CD7+ (CD2 or CD5)+ CD3- immature TL, and CD7+ CD2+ CD5+ CD3+ mature TL. RESULTS: Similar induction outcomes of 91.4%, 97.1%, and 98.3% were obtained by the pro-, immature, and mature TL groups, respectively. Four-year event-free survival (EFS) was lower for pro-TL patients (57.1%; SD = 8.4%,) compared with immature and mature TL patients (68.5%; SD = 3.5%; and 77.1%; SD = 4.0%, respectively) with an overall significance of .05 (log-rank test) or .04 (log-rank trend test). Relative hazards rates (RHR) were 2.11 and 1.22 for pro-TL and immature TL versus mature TL, respectively. Highly significant differences were found for overall survival (P = .005, log-rank test; P = .009, log-rank trend test). Multivariate analysis confirmed that the prognostic influence of ontogeny grouping was independent of that of other prognostic factors. CONCLUSION: Leukemic cells of the pro-TL maturation stage identify a small subgroup of T-lineage ALL patients who have a significantly worse EFS outcome than patients whose cells are of a more mature stage of development.

Prognostic impact of trisomies of chromosomes 10, 17, and 5 among children with acute lymphoblastic leukemia and high hyperdiploidy (> 50 chromosomes).

PURPOSE: Children with acute lymphoblastic leukemia (ALL) and high hyperdiploidy (> 50 chromosomes) have improved outcome compared with other ALL patients. We sought to identify cytogenetic features that would predict differences in outcome within this low-risk subset of ALL patients. MATERIALS AND METHODS: High-hyperdiploid ALL patients (N = 480) were enrolled between 1988 and 1995 on Children's Cancer Group (CCG) trials. Karyotypes were determined by conventional banding. Treatment outcome was analyzed by life-table methods. RESULTS: Patients with 54 to 58 chromosomes had better outcome than patients with 51 to 53 or 59 to 68 chromosomes (P = .0002). Patients with a trisomy of chromosome 10 (P<.0001), chromosome 17 (P = .0002), or chromosome 18 (P = .004) had significantly improved outcome compared with their counterparts who lacked the given trisomy. Patients with a trisomy of chromosome 5 had worse outcome than patients lacking this trisomy (P = .02). Patients with trisomies of both chromosomes 10 and 17 had better outcome than those with a trisomy of chromosome 10 (P = .09), a trisomy of chromosome 17 (P =.01), or neither trisomy (P<.0001). Multivariate analysis indicated that trisomy of chromosome 10 (P = .001) was the most significant prognostic factor for high-hyperdiploid patients, yet trisomy of chromosome 17 (P =.02) or chromosome 5 (P = .01) and modal chromosome number (P = .02) also had significant multivariate effects. CONCLUSION: Trisomy of chromosomes 10 and 17 as well as modal chromosome number 54 to 58 identify subgroups of patients with high-hyperdiploid ALL who have a better outcome than high-hyperdiploid patients who lack these cytogenetic features. Trisomy of chromosome 5 confers poorer outcome among high-hyperdiploid patients.

Duration of hospitalization as a measure of cost on Children's Cancer Group acute lymphoblastic leukemia studies.

PURPOSE: We used duration of hospitalization as a surrogate for cost and event-free survival as a measure of effectiveness to estimate the cost-effectiveness ratios of various treatment regimens on Children's Cancer Group trials for acute lymphoblastic leukemia. PATIENTS AND METHODS: The analyses included 4,986 children (2 to 21 years of age) with newly diagnosed acute lymphoblastic leukemia enrolled onto risk-adjusted protocols between 1988 and 1995. Analyses were based on a model of 100 patients. The marginal cost-effectiveness ratio (hospital days per additional patient surviving event-free) was the difference in total duration of hospitalization divided by the difference in number of event-free survivors at 5 years for two regimens. Relapse-adjusted marginal cost of frontline therapy was the difference in total duration of hospitalization for frontline therapy plus relapse therapy divided by the difference in number of event-free survivors at 5 years on the frontline therapy for two regimens. RESULTS: One or two delayed intensification (DI) phases, augmented therapy, and dexamethasone all improved outcome. Marginal cost-effectiveness of these regimens compared with the control regimens was 133 days per patient for DI, 117 days per patient for double DI, and 41 days per patient for augmented therapy. Dexamethasone resulted in 17 fewer days per patient. Relapse-adjusted marginal costs were 68 days per patient for DI and 52 days for double DI. Augmented therapy and dexamethasone-based therapy resulted in 16 and 82 fewer hospital days, respectively. The estimated cost-effectiveness for treating any first relapse was 250 days per patient. CONCLUSION: DI, double DI, augmented therapy, and dexamethasone-based therapy are cost-effective strategies compared with current treatment of first relapse.

High-dose carboplatin, thiotepa, and etoposide with autologous stem-cell rescue for patients with recurrent medulloblastoma. Children's Cancer Group.

PURPOSE: Medulloblastoma is a highly lethal disease when it recurs. Very few patients survive with conventional treatment. This study evaluated the use of high-dose carboplatin, thiotepa, and etoposide with autologous stem-cell rescue (ASCR) in patients with recurrent medulloblastoma. METHODS: Chemotherapy consisted of carboplatin 500 mg/m2 (or area under the curve = 7 mg/mL x min via Calvert formula) on days -8, -7, and -6; and thiotepa 300 mg/m2 and etoposide 250 mg/m2 on days -5, -4, and -3; followed by ASCR on day 0. In addition to the study-prescribed therapy, 21 patients received other treatment: neurosurgical resection in seven, conventional chemotherapy in 17, and external-beam irradiation in 11 cases. RESULTS: Twenty-three patients with recurrent medulloblastoma, aged two to 44 years (median, 13 years) at ASCR, were treated. Three patients died of treatment-related toxicities within 21 days of ASCR; multiorgan system failure in two, and Aspergillus infection with venoocclusive disease in one. Seven of 23 patients (30%) are event-free survivors at a median of 54 months post-ASCR (range, 24 to 78 months). Kaplan-Meier estimates of event-free (EFS) and overall survival are 34% +/- 10% and 46% +/- 11%, respectively, at 36 months post-ASCR. CONCLUSION: This strategy may provide long-term survival for some patients with recurrent medulloblastoma.

Pilot study of high-dose thiotepa and etoposide with autologous bone marrow rescue in children and young adults with recurrent CNS tumors. The Children's Cancer Group.

PURPOSE: This study was designed to determine the toxicity, radiographic response rate, and outcome following high-dose thiotepa, etoposide, and autologous bone marrow rescue (ABMR) for young patients with recurrent malignant brain tumors. METHODS: Eligibility criteria required adequate renal, hepatic, and pulmonary function, and no bone marrow infiltration. Thiotepa 300 mg/m2 and etoposide 500 mg/ m2 were infused on 3 consecutive days, and autologous bone marrow was infused 72 hours following chemotherapy. RESULTS: Forty-five patients with recurrent high-grade brain tumors, aged 8 months to 36 years (median, 8 years), were treated. Seven patients (16%) died of treatment-related toxicities within 56 days of marrow reinfusion. Delayed platelet engraftment occurred in 44% of patients who survived beyond day 56. Of 35 patients with radiographically measurable disease who survived at least 28 days following ABMR, there were two complete responses (CRs) and six partial responses (PRs), for an overall response (CRs plus PRs) rate of 23% (SE = 7%). Objective responses were observed in four of 14 assessable patients with high-grade glioma and in two of six with primitive neuroectodermal tumors (PNETs)/ medulloblastoma. Survival was significantly improved in patients treated with minimal residual disease (P < .0005). Five of 18 patients (28%) with high-grade gliomas remain free of disease at 39+, 44+, 49+, 52+, and 59+ months post-ABMR. CONCLUSION: The combination of high-dose thiotepa and etoposide has activity against a variety of recurrent childhood brain tumors. These results merit further evaluation in children and young adults with both recurrent and newly diagnosed high-grade brain tumors.

Abnormalities of chromosome bands 13q12 to 13q14 in childhood acute lymphoblastic leukemia.

PURPOSE: Little is known about nonrandom deletions of chromosome bands 13q12 to 13q14 (13q12-14) in acute lymphoblastic leukemia (ALL). We determined the prognostic significance of cytogenetically identified breakpoints in 13q12-14 in children with newly diagnosed ALL treated on Children's Cancer Group protocols from 1988 to 1995. PATIENTS AND METHODS: Breakpoints in 13q12-14 were identified in 36 (2%) of the 1,946 cases with accepted cytogenetic data. Outcome analysis used standard life-table methods. RESULTS: Seventeen patients (47%) with an abnormal 13q12-14 were classified, according to the National Cancer Institute (NCI), as poor risk, and 15 patients (42%) were standard risk; four (11%) were infants less than 12 months of age. Eight cases had balanced rearrangements of 13q12-14, 27 patients had a partial loss of 13q, and one had both a partial gain and a partial loss. The most frequent additional abnormalities among these patients were an abnormal 12p, a del(6q), a del(9p), a 14q11 breakpoint, and an 11q23 breakpoint. Nineteen patients were pseudodiploid, 10 were hyperdiploid, and seven were hypodiploid. Patients with an abnormal 13q12-14 had significantly worse event-free survival than patients lacking such an abnormality, with estimates at 6 years of 61% (SD = 14%) and 74% (SD = 1%), respectively (P =.04; relative risk = 1.74). Overall survival, however, was similar for the two groups (P =.25). The prognostic effect of an abnormal 13q was attenuated in a multivariate analysis adjusted for NCI risk status and ploidy (P =.72). CONCLUSION: Aberrations of 13q12-14 may contribute to leukemogenesis of childhood ALL and confer increased risk of treatment failure but are associated with other poor-risk features.

Deletion of 7p or monosomy 7 in pediatric acute lymphoblastic leukemia is an adverse prognostic factor: a report from the Children's Cancer Group.

Monosomy 7 or deletions of 7q are associated with many myeloid disorders; however, the significance of such abnormalities in childhood acute lymphoblastic leukemia (ALL) is unknown. Among 1880 children with ALL, 75 (4%) had losses involving chromosome 7, 16 (21%) with monosomy 7, 41 (55%) with losses of 7p (del(7p)), 16 (21%) with losses of 7q (del(7q)), and two (3%) with losses involving both arms. Patients with losses involving chromosome 7 were more likely to be > or =10 years old, National Cancer Institute (NCI) poor risk, and hypodiploid than patients lacking this abnormality. Patients with or without these abnormalities had similar early response to induction therapy. Event-free survival (EFS) and survival for patients with monosomy 7 (P<0.0001 and P=0.0007, respectively) or del(7p) (P<0.0001 and P=0.0001, respectively), but not of patients with del(7q), were significantly worse than those of patients lacking these abnormalities. The poorer EFS was maintained after adjustment for a Philadelphia (Ph) chromosome, NCI risk status, ploidy, or an abnormal 9p. However, the impact on survival was not maintained for monosomy 7 after adjustment for a Ph. These results indicate that the critical region of loss of chromosome 7 in pediatric ALL may be on the p-arm.

Stimulation of human committed bone marrow stem cells (CFU-GM) by chloramphenicol.

Chloramphenicol, an antibiotic associated with reversible bone marrow suppression and fatal aplastic anemia, was found to increase human bone marrow granulocyte-macrophage colonies (CFU-GM) in vitro. Maximal stimulation was at a concentration of 1.0 micrograms/ml (3.1 microM), with inhibition at concentrations greater than 10 micrograms/ml. This effect was noted in normal donors and in children with neutropenia of various etiologies. Stimulation was ablated by depletion of bone-marrow-adherent cells and was restored by addition of peripheral-blood-adherent mononuclear cells. The stimulatory effect appears to be specific for chloramphenicol, as numerous structural analogues of chloramphenicol, including its three stereoisomers, did not show stimulation. The stimulation was present at plateau concentrations of colony-stimulating activity, suggesting that the stimulatory effect is not due to elaboration of excess colony-stimulating activity by chloramphenicol. We hypothesize that low concentrations of chloramphenicol stimulate CFU-GM by a highly specific interaction with adherent mononuclear cells and elaboration of an undefined growth factor.

Depot characteristics and biodistribution of interleukin-2 liposomes: importance of route of administration.

Due to rapid clearance of interleukin-2 (IL-2), it has had limited effective use as an in vivo immunostimulant. Current experimental and clinical protocols generally must utilize large doses, multiple injections, or continuous infusions of IL-2 in order to achieve significant immunostimulation, often at the expense of systemic toxicity. Therefore, the pharmacodynamics of IL-2 liposomes were investigated. IL-2 liposome incorporation efficiency was 80.4% (SD 5.5); vesicle diameter was 1.65 microns (SD 0.09) as determined by fluorescence-activated cell sorting (FACS). Both formulation (free cytokine vs. IL-2 liposomes) and route of administration were important variables in determination of the biodistribution and pharmacokinetic characteristics of IL-2. When free [125I]IL-2 was given i.v. to mice, only 6.5% was in the blood and 3% in liver and spleen 2 h after injection; on the other hand, at 2 h greater than 70% of i.v. [125I]IL-2 liposomes were detected in the blood, liver, spleen, and lungs. Mean i.v. elimination t1/2 from the blood of rats given 20 x 10(6) U/kg free cytokine or IL-2 liposomes was 41 versus 102 min, respectively, as measured by bioassay and 59 and 119 min as measured by enzyme immunoassay (EIA). After i.v. administration, the estimated Vd of IL-2 liposomes was 13-fold smaller than the free cytokine. Intrathoracic (i.tx.), i.p., and s.c. administration of [125I]IL-2 to mice also demonstrated significant depot effects when IL-2 was incorporated into liposomes. These data suggest IL-2 liposomes may provide in vivo immunostimulation superior to the free cytokine due to biodistribution and depot characteristics.

Comparison of two total body irradiation regimens in allogeneic bone marrow transplantation for acute non-lymphoblastic leukemia in first remission.

Between November 1976 and December 1987, 84 patients with newly diagnosed acute non-lymphoblastic leukemia who had achieved complete remission underwent non T-cell depleted allogeneic bone marrow transplantation from Human Leukocyte Antigen-Mixed Lymphocyte Culture (HLA-MLC) matched sibling donors. The first 36 patients (November 1976-June 1983) were prepared with cyclophosphamide, 60 mg/kg/day, IV for 2 days and single fraction total body irradiation with 750 cGy at a dose rate of 26 cGy/minute (Group I). The next 48 patients (July 1983-December 1987) were prepared with similar chemotherapy, but received hyperfractionated total body irradiation with total 1320 cGy, 165 cGy twice a day at a dose rate of 10 cGy/minute (Group II). Patient characteristics between these two groups are similar except for the significantly older age distribution in Group II. Median follow-up of Groups I and II are 8 years and 11 months and 2 years and 3 months, respectively. The Kaplan-Meier relapse-free survival, survival, and relapse rates at 3 years are 56, 58, and 19% in Group I and 69 (p = 0.22), 77 (p = 0.07), and 10% (p = 0.37) in Group II. There is no difference in the incidence of interstitial pneumonitis, viral or idiopathic, engraftment rate, or incidence of graft versus host disease (GVHD) between these two groups. The fractionated total body irradiation treated group had significantly less nausea and vomiting. Multivariate analysis shows that total body irradiation regimen is not a significant factor in regard to relapse rate, relapse-free survival, and survival.

Clinical collection and use of peripheral blood stem cells in pediatric patients.

Peripheral blood stem cells have been used in lieu of marrow as autologous cellular support after marrow-ablative radio/chemotherapy. Autologous marrow support allows the use of higher, more effective doses of therapy. Peripheral blood stem cells (PBSC) offer the potential for this form of "transplant" in patients with marrow involved with disease. PBSC use also allows the avoidance of marrow harvest under general anesthesia. Previous reports of PBSC use have been limited to adults. This article describes peripheral blood stem cell collection in children, and documents the successful use of such cells in a 21/2-year-old boy and a 3-year-old girl with progressive stage IV neuroblastoma involving the marrow. Collections were performed using a Fenwal CS3000 blood cell processor primed with fresh frozen plasma and red cells, using a low flow rate to avoid citrate toxicity. The transplant was performed using collections that were negative or low in neuroblastoma cells (as detected by anti-neuron-specific enolase and antineuroblastoma monoclonal antibodies) after preparation with high-dose cyclophosphamide, etoposide, and cisplatin. Posttransplant recovery was uneventful, and engraftment was comparable to that in 4 patients treated with a similar preparative regimen followed by infusion of autologous marrow. Using careful technique, PBSC support in lieu of marrow may be a viable treatment modality in pediatric neuroblastoma or other solid tumors, particularly when the marrow is involved with disease.

Collection and use of peripheral blood stem cells in very small children.

Collections of peripheral blood stem cells (PBSC) from children weighing less than 25 kg have been limited by concern about citrate toxicity. We developed a modified collection technique on the Fenwal CS3000 blood cell separator and used it in three children weighing 8.3, 20 and 24 kg with neuroblastoma involving the marrow. The saline prime was discarded as a mixture of 250 ml red cells, 100 ml fresh frozen plasma, and 100 ml 5% albumin was run into the separator. Heparin (1500 units/h) was used to supplement ACD, which was infused at a low rate (1:25-1:32 vs blood, vs the usual 1:13). No serious difficulties were encountered during or after the collections. A total of 5.7, 4.8 and 6.4 x 10(8) mononuclear cells/kg were collected in six procedures per patient. After cell cryopreservation and patient preparation using high-dose chemotherapy, the cells were thawed in 37 degrees C saline and infused without incident. Hematopoietic recovery was observed, and one of the patients remains in clinical remission after 11 months of follow-up. The addition to previously developed procedures of the use of partial albumin prime, low citrate anticoagulation, and heparin allows convenient and safe collection of PBSC in extremely small children, and these PBSC are effective.

Busulfan pharmacokinetics do not predict relapse in acute myeloid leukemia.

The purpose of this study was to evaluate the influence of busulfan (BU) pharmacokinetics on survival, grades II-IV acute graft-versus-host disease (GVHD), non-relapse mortality (NRM) and relapse in a group composed of 45 children (<18 years) and seven adults with acute myeloid leukemia (AML) in first complete remission and undergoing hematopoietic stem cell transplantation (SCT). Fifty-two patients underwent autologous (n = 25) or allogeneic (n = 27) SCT. The median age was 8.9 years (range 0.6-53 years). Conditioning therapy consisted of BU and cyclophosphamide. Improved disease-free survival was found in those patients with a steady-state concentration of BU (CssBU) below the median (<578 mg/ml, P = 0.05), and the same trend was noted for overall survival (P = 0.07). This was secondary to a higher incidence of NRM in the group of patients with CssBU above the median (P = 0.06). There was no significant correlation with CssBU and relapse (P = 0.31). No association between CssBU and GVHD was found in allogeneic patients (P = 0.30). Relapse was evaluated among the subgroups of age (< or >10 years) and transplant type (allogeneic or autologous) with no statistically significant association observed among these factors. Multiple regression analysis for relapse revealed no significant correlation with CssBU above or below the median, age, or transplant type. In this study, CssBU below the median did not correlate with an inferior outcome for patients with AML. Pharmacokinetic dosing of BU may be important for prevention of NRM but does not appear to influence the risk of relapse in this largely pediatric population with AML.

Bone marrow transplantation for advanced acute leukemia: a pilot study of high-energy total body irradiation, cyclophosphamide and continuous infusion etoposide.

Leukemic relapse following bone marrow transplantation (BMT) for acute leukemia is the most common cause of treatment failure. Because a more intensive pre-transplant preparative regimen may prevent disease recurrence we have designed a novel intensive conditioning regimen for BMT using high-energy total body irradiation (total dose 850 cGy; energy 24 MV; midplane received dose rate 26 cGy/min; day -6) followed by cyclophosphamide (dose 50 mg/kg/day; schedule 2-h infusion; days -5, -4, -3) and continuous infusion high-dose etoposide (dose 500 mg/m2/day; schedule: 22-h infusion; days -5, -4, -3). Between February 1987 and December 1988, 45 patients with advanced acute leukemia received transplants using this regimen. Twenty-five purged auto-transplants were done for B-lineage (n = 18), T-lineage (n = 6) or biphenotypic (n = 1) acute lymphoblastic leukemia, with 12 in remission and 13 in relapse at the time of transplantation. Of these, nine had non-relapse deaths and 16 have relapsed between 1 and 19 months (median 3 months) following transplantation. Of note all the T-lineage patients relapsed including two transplanted in remission and five transplanted in relapse. Nineteen patients received histocompatible allogeneic transplants and one underwent syngeneic transplantation. Of seven patients with acute lymphoblastic leukemia transplanted in refractory relapse, three have had an overt relapse, three died of interstitial pneumonitis and only one survives disease free 15 months after transplantation. Of 13 patients with acute non-lymphocytic leukemia and variants (11 who were transplanted in relapse) three died without relapse, three have relapsed and seven survive disease free from 9 to 27 months (median 20 months) after transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship of plasma pharmacokinetics of high-dose oral busulfan to the outcome of allogeneic bone marrow transplantation in children with thalassemia.

We analyzed plasma pharmacokinetics of busulfan in 64 children and young adults (age 2.8-26; median 11 years) with homozygous beta-thalassemia transplanted with bone marrow from HLA-identical sibling donors. A uniform conditioning regimen was employed, using busulfan 14 or 16 mg/kg in 12 divided doses, and cyclophosphamide 120 or 200 mg/kg. Three sets of parameters were examined in this homogenous patient population: (1) factors that affect the plasma kinetics of busulfan, such as age and pre-transplant liver status defined by liver function tests, ferritin levels and liver biopsy; (2) busulfan-related toxicity: occurrence of veno-occlusive disease, seizures and idiopathic interstitial pneumonitis; and (3) the relationship between busulfan exposure and transplant outcome: engraftment delay or rejection, aplasia, occurrence of mixed chimeras and mortality. Kinetic analysis of first and 10th dose (using area under the curve (AUC), maximum and minimum concentration) as comparable, showing no sign of accumulation or decline in busulfan plasma levels over time. Age and liver status did not influence busulfan metabolism. No relationship was found between busulfan exposure and toxicities or transplant outcome. We conclude that busulfan monitoring is not predictive in children and young adults with homozygous beta-thalassemia receiving busulfan and high-dose cyclophosphamide along with histocompatable sibling donor marrow.