Association between busulfan exposure and outcome in children receiving intravenous busulfan before hematopoietic stem cell transplantation.

BACKGROUND AND OBJECTIVE: Intravenous (IV) busulfan (Bu) combined with therapeutic drug monitoring-guided dosing is associated with better event-free survival (EFS), lower transplant-related mortality. But optimal target steady-state concentration (Css) of Bu in children undergoing hematopoietic stem cell transplantation (HSCT) remains unclear. This study aimed to evaluate the relation between Css of Bu and clinical outcomes in children receiving Bu before HSCT. METHODS: This study includes 75 children receiving IV Bu in 16 doses, with first dose assigned based on age. Bu first-dose pharmacokinetic parameters were estimated from Bu plasma concentrations measured at 6 time points by high-performance liquid chromatography. Doses were adjusted at the fifth dose to a target Css of 600-900 ng/mL. Cumulative incidence of overall survival (OS), EFS, transplant-related mortality, acute graft-versus host disease (aGVHD), and other toxicities in relation to Css of Bu were analyzed using Kaplan-Meier curves in univariate and Cox's proportional hazards model in multivariate analysis. RESULTS: After the first dose, median Css was 578 (325-1227) ng/mL. Forty-one patients had Bu IV dose increased by > 10%. Neutrophil and platelet recoveries, grade 2-4 aGVHD, and nonrelapse mortality (NRM) incidences were 90%, 91%, 12%, and 13%, respectively. Relapse incidence was 33%. Incidence of veno-occlusive disease, hemorrhagic cystitis, and lung toxicities were 13%, 24%, and 7%, respectively. OS and EFS were 70% and 58%. First-dose Bu Css >600 ng/mL was associated with a higher NRM (P < 0.001) and grade 2-4 aGVHD (P = 0.04), a lower EFS (P < 0.001), and OS (P = 0.001). CONCLUSIONS: This study demonstrated a significant association between the first-dose pharmacokinetics of Bu and NRM, OS, and EFS. Bu therapeutic drug monitoring provides information that potentially influences outcomes of HSCT in pediatric patients.

CD8(+) T-cell reconstitution in recipients of umbilical cord blood transplantation and characteristics associated with leukemic relapse.

Recipients of umbilical cord blood (UCB) transplantation (UCBT) face a high risk of morbidity and mortality related to opportunistic infections (OI) and leukemic relapse. To understand the molecular basis of these UCBT-related complications, the characteristics of UCB-derived antigen-specific CD8(+) T cells were examined in a group of pediatric UCBT recipients. Compared with the UCB graft inoculum and the late post-UCBT period (12-36 months), declining clonal diversity of UCB-derived CD8(+) T cells specific for the Melan-A(26-35) A27L peptide and high frequencies of PD-1-expressing CD8(+) T cells were observed in the first 3 months after UCBT, a period during which OIs are most frequent. The CD8(+) T-cell compartment predominantly comprised CD45RA(+) CCR7(-) terminally differentiated effector-memory T cells until 6 months after UCBT, at which time the polyfunctionality of antigen-specific CD8(+) T cells was reestablished. Finally, the frequency of PD-1(+) CD8(+) T cells was significantly higher in subjects who subsequently experienced leukemic relapse. This study informs the biologic properties of UCB-derived CD8(+) T cells and provides a rationale for the characteristics of UCBT in terms of immune reconstitution and OI. These results also suggest that the elevated frequency of PD-1(+) CD8(+) T cells could be associated with leukemic relapse in pediatric UCBT recipients.

Impact of storage temperature and processing delays on cord blood quality: discrepancy between functional in vitro and in vivo assays.

BACKGROUND: Optimal conditions of cord blood (CB) storage, processing, cryopreservation, and thawing are critical for banking and transplantation. Nevertheless, standardized procedures are still awaited. STUDY DESIGN AND METHODS: We evaluated the impact of preprocessing storage and temperature on recovery, viability, and functional differentiation capacities of hematopoietic progenitor cells. We compared units stored at room temperature (RT) or at 4 °C for 72 hours before cryopreservation to units processed shortly after collection (<12 hr). RESULTS: Postthaw results showed similar in vitro characteristics between immediate processing and 4 °C storage for cell recovery and viability, both significantly higher than RT storage. Surprisingly, we demonstrated that storage of CB units at RT before processing and cryopreservation profoundly altered in vivo hematopoietic reconstitution in mice, although in vitro hematopoietic colony-forming unit potential was unaltered. CONCLUSION: Our findings challenge current CB storage practices and suggest standard in vitro quality assessments may not always be indicative of CB engraftment potential.

Umbilical cord blood T cells respond against the Melan-A/MART-1 tumor antigen and exhibit reduced alloreactivity as compared with adult blood-derived T cells.

Umbilical cord blood (UCB) is increasingly used as a source of hematopoietic progenitor cells to treat a variety of disorders. UCB transplant is associated with comparatively reduced incidence of graft-versus-host disease, robust graft versus leukemia effect, and relatively high incidence of opportunistic infections, three processes in which donor-derived T lymphocytes are known to be predominantly involved. To examine the differential functionality of UCB T cells, CD8(+) T cells specific for the melanoma-associated HLA-A2-restricted Melan-A(26-35) A27L peptide were isolated from HLA-A2(+) and HLA-A2(-) UCB samples and HLA-A2(+) and HLA-A2(-) adult peripheral blood using A2/Melan-A tetramers. In UCB samples, A2/Melan-A(+) CD8(+) T cells were detected at a frequency of 0.04%, were more frequent in HLA-A2(+) UCB, and were polyclonal and mostly naive. Consistent with Ag-driven expansion, the frequency of A2/Melan-A(+) CD8(+) T cells was increased following stimulation with cognate peptide or polyclonal activation, they acquired cell-surface markers reflective of effector/memory differentiation, their TCR repertoire became oligoclonal, and they expressed cytolytic activity and produced IFN-gamma. Although functional properties of A2/Melan-A(+) CD8(+) T cells derived from HLA-A2(+) UCB resembled those of HLA-A2(+) adult peripheral blood, they were more likely to reach terminal differentiation following polyclonal stimulation and produced less IFN-gamma in response to cognate peptide. A2/Melan-A(+) CD8(+) T cells from HLA-A2(-) UCB were poorly cytolytic, produced little IFN-gamma, and were predominantly monofunctional or nonfunctional. These properties of UCB-derived CD8(+) T cells could contribute to the reduced incidence of graft-versus-host disease and heightened incidence of opportunistic infections observed following UCB transplant.

Secondary pulmonary alveolar proteinosis after unrelated cord blood hematopoietic cell transplantation.

PAP is a rare alveolointerstitial lung disorder characterized histologically by the intra-alveolar accumulation of eosinophilic and PAS-positive material. We observed two cases of PAP after unrelated CB hematopoietic progenitor cell transplantation in children with ALL. No antagonist activity toward GM-CSF was identified in the patient tested. The putative multifactorial PAP etiology is discussed. This potentially curable condition should be considered in a CB allograft recipient with alveolointerstial lung disorder.

Higher dose imatinib for children with de novo chronic phase chronic myelogenous leukemia: a report from the Children's Oncology Group.

PURPOSE: To determine the efficacy of imatinib in children with newly diagnosed chronic phase (CP) chronic myelogenous leukemia (CML). METHODS: This was an open label, multi-center phase II clinical trial. Courses were defined as consecutive 28-day intervals. Oral imatinib was administered daily at 340 mg/m² without interruption in the absence of toxicity. RESULTS: Fifty-one children received 978 28-day courses of imatinib. The most common toxicities encountered were hematologic. Forty-one patients (80%) achieved a complete hematologic response by the end of course 2. Nineteen children (38%) obtained a complete cytogenetic response (CCyR) at the end of course 3. Overall, 72% achieved CCyR at a median time of 5.6 months. The rate of complete molecular response (>3 log reduction) was 27%. Progression-free and overall survival at 3 years were 72% ± 6.4% and 92% ± 3.9%, respectively. CONCLUSIONS: Daily oral imatinib at a dose of 340 mg/m² is well tolerated in children. In addition, imatinib therapy is effective in inducing a high percent of hematologic, cytogenetic and molecular responses, comparable to adults with CML. (This study was registered at ClinicalTrials.gov under identifier NCT00030394.).

Varicella-zoster virus disease is more frequent after cord blood than after bone marrow transplantation.

Immune reconstitution may differ following cord blood transplantation (CBT) and bone marrow transplantation (BMT), and this may lead to a difference in varicella zoster virus (VZV) disease rates. One hundred fourteen VZV seropositive children received a CBT (37 patients), or a T-replete BMT (77 patients) at our institution. Patients did not received specific VZV disease prophylaxis. VZV disease was diagnosed by immunofluorescence or culture in 41 (36%) patients. In multivariate analysis, VZV disease was more frequent in older children (relative risk [RR] 1.11 per year; 95% confidence interval [CI], 1.04-1.18; P = .002), and after CBT (RR 2.27; 95% CI, 1.18-4.34; P = .013). The cumulative incidence of VZV disease at 3 years posttransplant was 46% following CBT. VZV disease incidence was 71% in CBT patients over 10 years old at transplant. Visceral dissemination occurred in 7 patients (6 CBT and 1 BMT) (P = .005). VZV disease is thus more frequent and more severe after CBT than after BMT.

IV busulfan dose individualization in children undergoing hematopoietic stem cell transplant: limited sampling strategies.

We currently calculate area under the busulfan concentration time curve (AUC) using 7 plasma busulfan concentrations (AUC7) drawn after the first of 16 i.v. busulfan doses given as a 2-hour infusion every 6 hours. The aim of this study was to develop and validate limited sampling strategies (LSSs) using 3 or fewer busulfan concentration values with which to reliably calculate AUC in children undergoing hematopoietic stem cell transplant (HSCT). Children in the development group (44) received i.v. busulfan at Sick Kids; the validation group consisted of 35 children who received care at CHU Ste-Justine. Busulfan doses given and subsequent plasma busulfan concentrations were recorded. LSSs using 1 to 3 concentration-time points were developed using multiple linear regression. LSS were considered to be acceptable when adjusted r(2) > 0.9, mean bias <15% and precision <15%. Extent of agreement between the AUC7 values and the LSS AUC was assessed by the intraclass correlation coefficient (ICC) and Bland-Altman (BA) analysis. Agreement was considered to be excellent when the lower limit of the 95% confidence limit of the ICC exceeded 0.9 and when the limits of agreement in the BA analysis were +/-15% for both AUC and dose. Administration of the theoretic adjusted busulfan doses based on each LSS was simulated and cases where the resulting AUC was >1500 or <900 microM x min were noted. LSSs using 1, 2, or 3 plasma busulfan concentrations were developed that showed excellent agreement with AUC7 and adjusted busulfan doses. In the validation sample, only the 2- and 3-point LSSs demonstrated acceptable precision and lack of bias. LSSs using 2 or 3 plasma busulfan concentrations can be used to reliably estimate busulfan AUC after IV administration in children undergoing HSCT.

Binding of thymoglobulin to natural killer cells leads to cell activation and interferon-gamma production.

Thymoglobulin is an antithymocyte globulin preparation used in hematopoietic stem cell transplantation (HSCT) to prevent rejection and graft-versus-host disease. Because natural killer (NK)-cell alloreactivity improves HSCT outcome, but only in patients receiving thymoglobulin, we investigated the in vitro effects of thymoglobulin on purified NK cells. Thymoglobulin binding to NK cells and NK-cell activation were assessed by flow cytometry. NK surface targets for thymoglobulin were determined by competition inhibition assays using monoclonal antibodies. Chromium 51 (Cr) release assay, Annexin V combined with 7-amino-actinomycin D staining, and carboxyfluorescein diacetate succinimidyl ester staining were used to study cytotoxic activity, apoptosis/cell death, and NK-cell proliferation, respectively. Interferon (IFN)-gamma production was determined by ELISA. Thymoglobulin, thymoglobulin derived-F(ab')2 fragments as well as rabbit IgG bound NK cells, and competed strongly with anti-CD16. Thymoglobulin enhanced the expression of activation (CD69 and NKG2D) and degranulation (CD107a) markers on NK cells. It competed with CD18 binding and decreased NK activity, but not interleukin-15-induced killer activity. Effects on apoptosis/cell death and proliferation were minimal. F(ab')2 fragments and rabbit IgG strongly induced IFN-gamma production by NK cells. Thymoglobulin binds to NK cells by CD16 by its variable and constant regions. The decrease in NK-cell cytotoxic activity is restored by interleukin-15, and contrasts sharply with the induction of activation, degranulation, and IFN-gamma production. These data support the hypothesis that thymoglobulin treatment is required to observe the improvement in HSCT outcome by NK-cell alloreactivity.

Long-term survival rate of pediatric patients after blood transfusion.

BACKGROUND: Studies in adults report posttransfusion survival rate (PTSR) at 1 to 10 years of 41 to 67 percent. There are no published studies specifically addressing PTSR in pediatric patients. The objectives of this study were to evaluate PTSR and risk factors associated with death in children receiving transfusions. STUDY DESIGN AND METHODS: A database of all patients receiving their first transfusion between 1990 and 1992 at Sainte-Justine Hospital (SJH) was used. Patients' demographic data, primary diagnosis, surgical procedures, and information on all labile components transfused were collected. Death was confirmed by the SJH database, RAMQ (universal health care provider for Québec residents), and the Quebec Commission for Access to Information (death certificate). RESULTS: The study population consisted of 1100 children. Median age was 16 months (range, 0-204 months). The most frequent primary diagnoses were cardiac disease (22%), prematurity (21.5%), malignant disease (11%), and hematologic disease (9.5%). Patients received a median of three transfusions (range, 1-126). PTSR was 86.9 percent at 1 year and 82.3 percent at 10 years. For nonsurvivors, median survival time was 22 days. Multivariate analysis showed that significant risk factors for death are age of less than 1 month, a diagnosis of malignant disease, more than 20 transfusions, and administration of more than one type of blood component. CONCLUSION: PTSR in children receiving their first transfusion between 1990 and 1992 was considerably higher than the PTSR reported in adults. Death occurred early after the first transfusion; survival rate remained relatively stable thereafter.

Complications of apheresis in children.

BACKGROUND: Although the frequency of complications in adults undergoing therapeutic apheresis is low, there are little data in children. STUDY DESIGN AND METHODS: A retrospective study of 186 children who had undergone a total of 1632 apheresis procedures between 1994 and 2002 was conducted. Adverse reactions were prospectively documented. The procedures were plasma exchange (67%), hematopoietic progenitor cell collection (18%), red blood cell exchange (6.9%), leukodepletion (0.7%), and plasma exchange with immunoadsorption (6.7%). RESULTS: Adverse reactions, most minor, were reported in 55 percent of procedures in 82 percent of patients. The most frequent complications, per procedure and per patient during an entire course of therapy, were hypotension (14 and 48.4%), hypotension requiring fluid bolus (4.8 and 26.9%), symptomatic hypocalcemia (9.7 and 28.5%), allergic reactions (4.4 and 5.9%), catheter-related thrombosis (1.7 and 12.4%), catheter-related infection (2.1 and 16.1%), and severe anemia (hemoglobin [Hb] level, <7 g/dL; 2.5 and 17.2%). There were two deaths (1% of patients). Risk factors for complications by multivariate analysis were lower body weight, lower preapheresis Hb level, apheresis in a critical care unit, and number of procedures per patient. The 55 percent incidence of complications per procedure in our pediatric cohort is much higher than the 4.3 to 28 percent incidence reported in adults. The excess of adverse reactions in children are mostly related to citrate toxicity, higher relative vascular volume shifts, and the need for vascular access. CONCLUSION: Pediatric apheresis presents unique challenges and is associated with higher complication rate compared to adults. It is recommended that this procedure be performed in specialized centers.

Results of unrelated cord blood transplant in fanconi anemia patients: risk factor analysis for engraftment and survival.

We retrospectively analyzed results of unrelated cord blood transplantation (UCBT) in 93 Fanconi anemia (FA) patients. Median age at transplantation was 8.6 years (1-45). The units transplanted were HLA-A, -B, or -DRB1 identical in 12 cases, 1 HLA mismatch in 35 cases, and 2 or 3 HLA differences in 45 cases. The median number of nucleated cells (NC) and CD34+ cells infused of recipient weight was 4.9x10(7)/kg and 1.9x10(5)/kg, respectively. Participating centers selected the preparative regimen of their choice, in 57 patients (61%), it included Fludarabine. Graft-versus-host disease (GVHD) prophylaxis consisted mostly of cyclosporine with prednisone. Cumulative incidence (CI) of neutrophil recovery was 60+/-5% at day +60. In multivariate analysis, Fludarabine containing regimen and NC infused>or=4.9x10(7)/kg were associated with higher probability of recovery. CI of grade II-IV acute and of chronic GVHD (aGVHD, cGVHD) was 32%+/-5% and 16%+/-4%, respectively. Overall survival (OS) was 40%+/-5%. In multivariate analysis, factors associated with favorable outcome were use of Fludarabine in the conditioning regimen, number of NC infused>or=4.9x10(7)/kg, and negative cytomegalovirus (CMV) serology in the recipient. In conclusion, factors easily modifiable such as donor selection and a Fludarabine-containing regimen can considerably improve survival in FA patients given a UCBT. These data are the basis for designing prospective protocols.

Assessment of cord blood unit characteristics on the day of transplant: comparison with data issued by cord blood banks.

BACKGROUND: Selection of a cord blood (CB) unit for allogeneic transplantation relies on graft characterization results provided by cord blood banks (CBBs). The goal was to compare the graft characterization results obtained upon thawing and washing to those provided by CBBs at selection. STUDY DESIGN AND METHODS: With tests that assess CB graft characteristics known to impact engraftment, CB units have been analyzed after thaw and before infusion. Our results were compared to data provided by CBBs to determine the impact on engraftment and assess how CBB-supplied information can affect future CB unit selection. RESULTS: Variability was noted as to the type of information provided by the different CBBs. Also, variability was found between the information provided by CBBs and the graft characterization results obtained upon thawing and washing. In some cases, CB measures known to be predictive of engraftment were found much lower than reported by CBBs. Only the total nucleated cell count, which is the main CB graft selection criterion besides HLA matching, correlated favorably. CONCLUSIONS: Our data reveal a high degree of variability in graft characteristics provided by CBBs and often poor correlation with results obtained on thawed and washed CB units. We suggest that standardized laboratory procedures aimed at graft characterization should be used by both CBBs and transplant centers to avoid unacceptable discrepancies.

Treatment complications in children diagnosed with neuroblastoma during a screening program.

PURPOSE: The Québec Neuroblastoma Screening Program was put in place to investigate the possibility of decreasing mortality from high-risk neuroblastoma through early screening. We assess treatment complications in the patients diagnosed during this screening program. PATIENTS AND METHODS: A total of 476,603 patients born during the screening period were eligible. Parents of 425,838 children (89%) agreed to participate in the 3-week screening, and 73% agreed to participate in the 6-month screening. Forty-five patients had neuroblastoma. We reviewed the medical and research charts for all patients diagnosed by screening. Follow-up was available from 8 to 13 years after screening. RESULTS: Forty-five patients were diagnosed by screening. All patients were treated according to the Pediatric Oncology Group recommendations of the time. All patients had surgery, and 29 patients received chemotherapy. No patient died from neuroblastoma. Eleven patients suffered complications from treatment. Two patients had life-threatening complications. CONCLUSION: In view of the lack of impact of screening programs on neuroblastoma mortality, evidence that many of the tumors detected through screening can be observed without treatment and the serious complications that may arise from therapy, we do not support neuroblastoma screening programs for children.

Characterization of cord blood natural killer cells: implications for transplantation and neonatal infections.

The role of natural killer (NK) cells in hematopoietic stem cell transplantation and in the control of neonatal infections is not yet clear. Donor-versus-recipient NK cell alloreactivity was found to improve outcome in some settings of hematopoietic stem cell transplantation. We hypothesized that the role of NK cells in cord blood (CB) transplantation and neonatal infections may depend on CB NK cell maturation stage. We therefore analyzed the expression of NK cell differentiation/phenotypic markers in human CB, as well as functional properties of purified CB NK cells. CD8 and CD57 expression was lower in CB than in adult NK cells. However, the expression of other differentiation markers was similar, as was cell surface density of CD56, the percentage of late NK cell precursors, interferon-gamma production, and the proliferative response of purified NK cells to IL-2. Spontaneous cytotoxic activity of purified CB NK cells against NK-sensitive targets was low but reached adult levels after treatment with IL-15. Expression of perforin and granzyme B was higher in CB NK cells (90 versus 58% and 86 versus 69%, respectively). intercellular adhesion molecule-1 and CD161 expression was lower in CB. Surprising, fewer CB NK cells expressed L-selectin, a marker of immature NK cells. Taken together, our results suggest that CB NK cells are phenotypically and functionally mature.

Second induction in pediatric patients with recurrent acute lymphoid leukemia using DFCI-ALL protocols.

Between 15% and 30% of children with acute lymphoblastic leukemia (ALL) experience disease recurrence. With the possible exception of patients presenting with late isolated extramedullary relapse, induction of second complete remission (CR) is employed as a stepping stone to allogeneic hematopoietic stem cell transplantation (HSCT). The authors report their institutional experience in the management of children with recurrent ALL using the Dana Farber Cancer Institute (DFCI) ALL protocol in patients treated initially with that same protocol. Successful reinduction was followed by allogeneic HSCT when possible. Between April 1986 and May 2003, 34 patients with recurrent ALL, treated at initial diagnosis with DFCI-ALL protocol therapy, were given the same protocol as repeat induction chemotherapy. The median age was 4.6 years at diagnosis and 7.1 years at recurrence. Median duration of CR1 was 30.3 months. Second CR was obtained in 29 (85%) patients. Twenty went on to allogeneic HSCT; 10 of them currently remain in CR. Two additional patients treated with chemotherapy without HSCT are also in continuous CR2. Overall, 13 (38%) of the 34 patients are alive with a median follow-up of 105 months. There were no toxic deaths due to the reinduction therapy. One child died of cardiac failure after autologous HSCT. The treatment of children with recurrent ALL using the DFCI-ALL protocol induction regimen after initial use of the same protocol is associated with a high rate of second CR with no excess toxicity. However, the overall prognosis in these patients remains unsatisfactory and needs to be improved.

Imatinib mesylate (STI571) for treatment of children with Philadelphia chromosome-positive leukemia: results from a Children's Oncology Group phase 1 study.

The purpose of this study was to determine dose-limiting toxicities and pharmacokinetics of imatinib in children with refractory or recurrent Philadelphia chromosome-positive (Ph(+)) leukemias. Oral imatinib was administered daily at dose levels ranging from 260 to 570 mg/m(2). Plasma pharmacokinetic studies were performed on days 1 and 8 of course 1. There were 31 children who received 479 courses of imatinib. The most common toxicities encountered, which occurred in less than 5% of courses, were grade 1 or 2 nausea, vomiting, fatigue, diarrhea, and reversible increases in serum transaminases. One patient at the 440-mg/m(2) dose level had dose-limiting weight gain. There were no other first-course dose-limiting toxicities. A maximum tolerated dosage was not defined. Among 12 chronic myeloid leukemia (CML) patients evaluable for cytogenetic response, 10 had a complete response and 1 had a partial response. Among 10 acute lymphoblastic leukemia (ALL) patients evaluable for morphologic response, 7 achieved an M1 and 1 achieved an M2 bone marrow. We observed marked interpatient variability in the pharmacokinetic parameters. In conclusion, we found that daily oral imatinib is well tolerated in children at doses ranging from 260 to 570 mg/m(2). Doses of 260 and 340 mg/m(2) provide systemic exposures similar to those of adults who are treated with daily doses of 400 and 600 mg, respectively.