Elucidation and Pharmacologic Targeting of Master Regulator Dependencies in Coexisting Diffuse Midline Glioma Subpopulations.

Diffuse Midline Gliomas (DMGs) are universally fatal, primarily pediatric malignancies affecting the midline structures of the central nervous system. Despite decades of clinical trials, treatment remains limited to palliative radiation therapy. A major challenge is the coexistence of molecularly distinct malignant cell states with potentially orthogonal drug sensitivities. To address this challenge, we leveraged established network-based methodologies to elucidate Master Regulator (MR) proteins representing mechanistic, non-oncogene dependencies of seven coexisting subpopulations identified by single-cell analysis-whose enrichment in essential genes was validated by pooled CRISPR/Cas9 screens. Perturbational profiles of 372 clinically relevant drugs helped identify those able to invert the activity of subpopulation-specific MRs for follow-up in vivo validation. While individual drugs predicted to target individual subpopulations-including avapritinib, larotrectinib, and ruxolitinib-produced only modest tumor growth reduction in orthotopic models, systemic co-administration induced significant survival extension, making this approach a valuable contribution to the rational design of combination therapy.

Immune Response following FLASH and Conventional Radiation in Diffuse Midline Glioma.

PURPOSE: Diffuse midline glioma (DMG) is a fatal tumor traditionally treated with radiation therapy (RT) and previously characterized as having a noninflammatory tumor immune microenvironment (TIME). FLASH is a novel RT technique using ultra-high dose rate that is associated with decreased toxicity and effective tumor control. However, the effect of FLASH and conventional (CONV) RT on the DMG TIME has not yet been explored. METHODS AND MATERIALS: Here, we performed single-cell RNA sequencing (scRNA-seq) and flow cytometry on immune cells isolated from an orthotopic syngeneic murine model of brainstem DMG after the use of FLASH (90 Gy/sec) or CONV (2 Gy/min) dose-rate RT and compared to unirradiated tumor (SHAM). RESULTS: At day 4 post-RT, FLASH exerted similar effects as CONV in the predominant microglial (MG) population, including the presence of two activated subtypes. However, at day 10 post-RT, we observed a significant increase in the type 1 interferon α/ß receptor (IFNAR+) in MG in CONV and SHAM compared to FLASH. In the non-resident myeloid clusters of macrophages (MACs) and dendritic cells (DCs), we found increased type 1 interferon (IFN1) pathway enrichment for CONV compared to FLASH and SHAM by scRNA-seq. We observed this trend by flow cytometry at day 4 post-RT in IFNAR+ MACs and DCs, which equalized by day 10 post-RT. DMG control and murine survival were equivalent between RT dose rates. CONCLUSIONS: Our work is the first to map CONV and FLASH immune alterations of the DMG TIME with single-cell resolution. Although DMG tumor control and survival were similar between CONV and FLASH, we found that changes in immune compartments differed over time. Importantly, although both RT modalities increased IFN1, we found that the timing of this response was cell-type and dose-rate dependent. These temporal differences, particularly in the context of tumor control, warrant further study.

The 2022 Hunga-Tonga megatsunami: Near-field simulation of a once-in-a-century event.

The Hunga Tonga-Hunga Ha'apai (HTHH) volcanic eruption in January 2022 generated catastrophic tsunami and contends for the largest natural explosion in more than a century. The main island, Tongatapu, suffered waves up to 17 m, and Tofua Island suffered waves up to 45 m, comfortably placing HTHH in the "megatsunami" league. We present a tsunami simulation of the Tongan Archipelago calibrated by field observations, drone, and satellite data. Our simulation emphasizes how the complex shallow bathymetry of the area acted as a low-velocity wave trap, capturing tsunami for more than 1 hour. Despite its size and long duration, few lives were lost. Simulation suggests that HTHH's location relative to urban centers saved Tonga from a worse outcome. Whereas 2022 seems to have been a lucky escape, other oceanic volcanoes have the capacity to spawn future tsunami at HTHH scale. Our simulation amplifies the state of understanding of volcanic explosion tsunami and provides a framework for assessment of future hazards.

Length of Stay and Health Care Utilization Among Pediatric Autologous Hematopoietic Cell Transplantation Recipients.

Autologous hematopoietic cell transplantation (autoHCT) has become a critical component in the treatment of pediatric malignancies, allowing for high-dose chemotherapy to be given safely and with greater efficacy in a subset of children at high risk for relapse. Risk factors associated with hospital length of stay (LOS) in adults undergoing autoHCT have been studied extensively; however, there is a paucity of studies describing risk factors associated with LOS and health care cost in children undergoing autoHCT. This study sought to identify factors influencing LOS and cost in pediatric autoHCT. We assessed LOS from autologous stem cell infusion from day 0 (D0) in 100 autoHCT admissions in 73 patients with malignant disease between 2007 and 2019. We evaluated demographic, pre-transplantation, post-transplantation, and socioeconomic variables to identify potential risk factors associated with LOS and cost. AutoHCT cost data were provided by the Pediatric Health Information System database. Indications for autoHCT included neuroblastoma (35.6%), brain tumor (27.4%), and relapsed lymphoma (24.7%). The median patient age was 4.88 years (range, 0.72 to 22 years), with 71% age <12 years, and the cohort was 63% male, 77% white, and 41% Hispanic. The median LOS from D0 was 19 days (range, 13 to 100 days). On multivariable analysis, age >12 years compared with 2 to 12 years (estimate, -8.9 days; 95% confidence interval [CI], -15.1 to -2.8; P = .004) and complete remission/very good partial response disease status (estimate, -5.0 days; 95% CI, -9.6 to -0.4 days; P = .031) were associated with a significantly decreased median LOS, whereas Hispanic ethnicity (estimate, +6.8 days; 95% CI, 1.1 to 12.6 days; P = .019), >5 days of fever (estimate, +7.3 days; 95% CI, 1.4 to 13.2 days; P = .015), and pediatric intensive care unit (PICU) LOS (estimate, +14.9 days; 95% CI, 1.8 to 28.0 days; P = .025) were associated with a significant increase in median LOS. The median cost per transplantation admission was $96,850 (range, $39,833 to $587,321). Multivariable analysis showed that age >12 years (estimate, -$6,776; 95% CI, -$71,787 to -$11,402; P = .007) or <2 years (estimate, -$32,426; 95% CI, -$53,507 to -$11,345; P = .003), and complete remission/very good partial response disease status (estimate, -$20,266; 95% CI, -$40,211 to -$322; P = .046) were associated with significantly decreased median cost, whereas >5 days of fever (estimate, +$58,886; 95% CI, $30,667 to $87,105; P < .001) and PICU admission (estimate, +$102,458; 95% CI, $23,843 to $181,076; P = .011) were associated with significantly increased median cost. In summary, fever and PICU stay were found to be risk factors for increased LOS and cost. Age <12 years and Hispanic ethnicity were risk factors for increased LOS, whereas age <2 years and >12 years and female sex were associated with decreased cost. Further investigation to determine specific factors influencing LOS and cost is warranted to identify potentially modifiable risks within these patient populations.

Low CD4 count may be a risk factor for non-tuberculous mycobacteria infection in pediatric hematopoietic cell transplant recipients.

BACKGROUND: HCT leaves patients in a relative state of immune deficiency both during their initial transplant admission and for several years following discharge. NTM are generally harmless colonizers of the outside environment, but for immunocompromised patients, they can cause significant disease due to a paucity of T-cell defense. While routine prophylaxis against NTM is recommended for patients with low CD4 counts in certain clinical settings (eg, AIDS), this is not yet established for HCT patients despite their higher risk. METHODS: Here we build upon our prior work to determine risk factors for NTM in pediatric HCT patients by comparing NTM patient characteristics to matched HCT controls. RESULTS: We followed 272 patients across a 13-year time period, with 11 cases of NTM. Patients with NTM had a significantly lower CD4 count at Day 365 than matched HCT controls (105.5 ± 97.0 cells/µl vs. 856.2 ± 446.1 cells/µl, respectively; p = .001). No other potential risk factors (eg, CMV, GvHD, disease type) were found to be statistically significant, including use of T-cell depleting agents. This is consistent with an average diagnosis of NTM at Day +323 (ie, outside immediate post-transplant period). All-cause mortality was similar between NTM and control HCT groups, with an NTM attributable mortality of <10%. CONCLUSION: Since reduced CD4 counts are associated with NTM, and cost and morbidity are high, azithromycin prophylaxis for CD4 count <200 cells/µl in high-risk patients should be considered.

Limitations of Applying the Hematopoietic Cell Transplantation Comorbidity Index in Pediatric Patients Receiving Allogeneic Hematopoietic Cell Transplantation.

Identifying which patients are at high risk for transplant-related mortality, prior to allogeneic hematopoietic cell transplantation (alloHCT), is crucial both to guide decision making with patients and families and to inform the alloHCT approach. There is a paucity of data evaluating the utility of the HCT comorbidity index (HCT-CI) in pediatric patients. We performed a retrospective cohort study of 188 patients who underwent alloHCT between January 2008 and October 2016 and assessed pretransplant comorbidities defined and weighted by the HCT-CI. The primary endpoint of our study was overall survival (OS). Kaplan-Meier method was used to assess survival estimates at 1-year post-transplant and did not differ based on HCT-CI scores: 78.7% (SE 6.69%) for HCT-CI = 0, 74.7% (SE 6.33%) for HCT-CI = 1 to 2, and 77.3% (SE 4.17%) for HCT-CI ≥3. Multivariable Cox proportional hazards analysis did not show HCT-CI having an effect on OS: hazard ratio (HR) of 0.633 (95% confidence interval [CI], 0.297 to 1.347) for HCT-CI scores 1 to 2 and HR of 0.935 (95% CI, 0.456 to 1.918) for HCT-CI scores ≥3 compared to scores of 0. The most frequent comorbidities observed were hepatic disease (mild in 29%, severe in 23%) and pulmonary disease (moderate in 15% and severe in 29%). However, only 55% were able to complete pulmonary function testing. Hepatic disease was based on transaminitis in 48% and by bilirubin alone in 26% of patients; 46% of patients with hepatic dysfunction had an underlying hemoglobinopathy and hyperbilirubinemia related to ongoing hemolysis. This study evaluates HCT-CI comorbidities in greater detail than has been performed previously in children undergoing alloHCT. We identify challenges with the HCT-CI in the pediatric population and highlight the comorbidities that may benefit from adjustments to their definition to create an improved risk assessment tool for children.

Extraformational sediment recycling on Mars.

Extraformational sediment recycling (old sedimentary rock to new sedimentary rock) is a fundamental aspect of Earth's geological record; tectonism exposes sedimentary rock, whereupon it is weathered and eroded to form new sediment that later becomes lithified. On Mars, tectonism has been minor, but two decades of orbiter instrument-based studies show that some sedimentary rocks previously buried to depths of kilometers have been exposed, by erosion, at the surface. Four locations in Gale crater, explored using the National Aeronautics and Space Administration's Curiosity rover, exhibit sedimentary lithoclasts in sedimentary rock: At Marias Pass, they are mudstone fragments in sandstone derived from strata below an erosional unconformity; at Bimbe, they are pebble-sized sandstone and, possibly, laminated, intraclast-bearing, chemical (calcium sulfate) sediment fragments in conglomerates; at Cooperstown, they are pebble-sized fragments of sandstone within coarse sandstone; at Dingo Gap, they are cobble-sized, stratified sandstone fragments in conglomerate derived from an immediately underlying sandstone. Mars orbiter images show lithified sediment fans at the termini of canyons that incise sedimentary rock in Gale crater; these, too, consist of recycled, extraformational sediment. The recycled sediments in Gale crater are compositionally immature, indicating the dominance of physical weathering processes during the second known cycle. The observations at Marias Pass indicate that sediment eroded and removed from craters such as Gale crater during the Martian Hesperian Period could have been recycled to form new rock elsewhere. Our results permit prediction that lithified deltaic sediments at the Perseverance (landing in 2021) and Rosalind Franklin (landing in 2023) rover field sites could contain extraformational recycled sediment.

A phase I trial of lenalidomide and radiotherapy in children with diffuse intrinsic pontine gliomas or high-grade gliomas.

PURPOSE: This study was performed to determine the maximum tolerated dose (MTD) or recommended phase 2 dose (RP2D) of the immunomodulatory agent, lenalidomide, when administered daily during 6 weeks of radiation therapy to children with newly diagnosed diffuse intrinsic pontine glioma (DIPG) or high-grade glioma (HGG) PATIENTS & METHODS: Children and young adults < 22 years of age with newly diagnosed disease and no prior chemotherapy or radiation therapy were eligible. Children with HGG were required to have an inoperable or incompletely resected tumor. Eligible patients received standard radiation therapy to a prescription dose of 54-59.4 Gy, with concurrent administration of lenalidomide daily during radiation therapy in a standard 3 + 3 Phase I dose escalation design. Following completion of radiation therapy, patients had a 2-week break followed by maintenance lenalidomide at 116 mg/m2/day × 21 days of a 28-day cycle. RESULTS: Twenty-nine patients (age range 4-19 years) were enrolled; 24 were evaluable for dose finding (DIPG, n = 13; HGG, n = 11). The MTD was not reached at doses of lenalidomide up to 116 mg/m2/day. Exceptional responses were noted in DIPG and malignant glioma (gliomatosis cerebri) notably at higher dose levels and at higher steady state plasma concentrations. The primary toxicity was myelosuppression. CONCLUSION: The RP2D of lenalidomide administered daily during radiation therapy is 116 mg/m2/day. Children with malignant gliomas tolerate much higher doses of lenalidomide during radiation therapy compared to adults. This finding is critical as activity was observed primarily at higher dose levels suggesting a dose response.

Diffuse midline glioma with novel, potentially targetable, FGFR2-VPS35 fusion.

We report a case of a slow-growing, diffuse, infiltrating glioma in the right brainstem of a 9-yr-old boy. The tumor was negative by immunohistochemical staining for histone H3 K27M, BRAF V600E, and IDH1 R132H mutations. Fluorescence in situ hybridization did not reveal a BRAF duplication. Genomic profiling of the tumor, by DNA methylation array and cancer whole-exome and transcriptome sequencing, was performed. This analysis showed copy-number alterations, including gains of several chromosomes. In addition, a novel fusion involving the first 17 exons of FGFR2 fused to exon 2 of VPS35 was identified. This novel fusion is predicted to result in activation of fibroblast growth factor receptor (FGFR) signaling and is potentially targetable using FGFR inhibitors. This tumor expands the spectrum of pediatric diffuse gliomas.

Excellent outcome of young children with nodular desmoplastic medulloblastoma treated on "Head Start" III: a multi-institutional, prospective clinical trial.

BACKGROUND: "Head Start" III, was a prospective clinical trial using intensive induction followed by myeloablative chemotherapy and autologous hematopoietic cell rescue (AuHCR) to either avoid or reduce the dose/volume of irradiation in young children with medulloblastoma. METHODS: Following surgery, patients received 5 cycles of induction followed by myeloablative chemotherapy using carboplatin, thiotepa, and etoposide with AuHCR. Irradiation was reserved for children >6 years old at diagnosis or with residual tumor post-induction. RESULTS: Between 2003 and 2009, 92 children <10 years old with medulloblastoma were enrolled. Five-year event-free survival (EFS) and overall survival (OS) rates (±SE) were 46 ±â€…5% and 62 ±â€…5% for all patients, 61 ±â€…8% and 77 ±â€…7% for localized medulloblastoma, and 35 ±â€…7% and 52 ±â€…7% for disseminated patients. Nodular/desmoplastic (ND) medulloblastoma patients had 5-year EFS and OS (±SE) rates of 89 ±â€…6% and 89 ±â€…6% compared with 26 ±â€…6% and 53 ±â€…7% for classic and 38 ±â€…13% and 46 ±â€…14% for large-cell/anaplastic (LCA) medulloblastoma, respectively. In multivariate Cox regression analysis, histology was the only significant independent predictor of EFS after adjusting for stage, extent of resection, regimen, age, and sex (P <0.0001). Five-year irradiation-free EFS was 78 ±â€…8% for ND and 21 ±â€…5% for classic/LCA medulloblastoma patients. Myelosuppression was the most common toxicity, with 2 toxic deaths. Twenty-four survivors completed neurocognitive evaluation at a mean of 4.9 years post-diagnosis. IQ and memory scores were within average range overall, whereas processing speed and adaptive functioning were low-average. CONCLUSION: We report excellent survival and preservation of mean IQ and memory for young children with ND medulloblastoma using high-dose chemotherapy, with most patients surviving without irradiation.

Financial impact of post-transplant complications among children undergoing allogeneic hematopoietic cell transplantation.

Complications following allogeneic hematopoietic cell transplantation (alloHCT) continue to be a significant challenge that often result in significant morbidity/mortality and increased healthcare utilization and cost. In this study, we analyzed the impact of post-alloHCT complications on healthcare utilization and cost during first year post-transplant. We analyzed data on 240 pediatric patients. Complications analyzed included kidney injury, liver injury, lung injury, viral infections, bacterial infections, fungal infections, and acute graft-versus-host disease (GVHD). Patients were divided into three groups based on the number of complications (0-1, 2-3, and >3). Cost was estimated from charges recorded in the Pediatric Health Information System database and hospital accounting records. Patients with >3 complications had higher healthcare utilization and cost, primarily driven by inpatient hospitalization and intensive care unit admissions. Multivariable analysis of risk factors identified bacteremia ($90,166, SE = 26,636, p < 0.001), lung injury ($108,529, SE = 28,196, p < 0.001), liver injury ($90,805, SE = 28,660, p = 0.002), and grade II-IV aGVHD ($137,866, SE = 28,472, p < 0.001) as associated with significantly increased cost. Our study highlights the significant impact complications have on the overall cost of alloHCT. The identification that complications associated with high morbidity (aGVHD, pulmonary disease) are also associated with the highest financial burden emphasizes the need for future research in these areas to expand management options and improve outcomes for our patients.

Risk Factors, Clinical Outcomes, and Cost-of-Care Related to Graft Failure in Pediatric Allogeneic Hematopoietic Cell Transplant Recipients.

Allogeneic hematopoietic cell transplantation (HCT) has the capacity to cure numerous malignant and nonmalignant disorders. A dreaded complication is graft failure (GF), as it puts patients at high risk of infection and disease relapse. There are few contemporary data on the risks, outcomes, and economic burden of GF in pediatric patients. In this study, we address this gap by focusing on 14 years of transplant at our single center, for which data are compared in 2 time periods: 2005 to 2010 (n = 146) and 2011 to 2018 (n = 144). In the 290 patients studied, the median age was 9.33 years, and 50.3% had malignant versus nonmalignant disease. Cell source included bone marrow (51%), cord blood (19.7%), unmanipulated peripheral blood stem cells (PBSCs; 12.1%), and CD34-selected PBSCs (17.2%). Twenty-one percent of patients had reduced-intensity conditioning (RIC), and 54.8% of transplants were fully HLA matched. Most patients received serotherapy with rabbit anti-thymocyte globulin (39.3%) or alemtuzumab (42.8%). The incidence of neutropenic and non-neutropenic GF (NGF and NNGF) was 6.6% and 3.8%, respectively. Multivariate analysis demonstrated alemtuzumab (odds ratio [OR], 6.256, P < .001) was the main variable associated with a higher rate of GF in both time periods, whereas RIC (OR, 11.8, P < .001) and cell source (CD34-selected PBSCs; OR, 4.22, P = .04) showed period-specific effects. Specifically, from time periods 1 to 2, cord blood transplants were discontinued at our center, with a concomitant increase in CD34-selected grafts and a shift from more episodes of NGF to NNGF. Overall survival was 69% in the entire HCT cohort and 50% among patients with GF. Survival among GF patients improved from time periods 1 to 2 (20% versus 80%, P = .001), potentially due to a higher incidence of NNGF and increased ability to perform stem cell boosts from the same donor once cord blood transplants were phased out. Inpatient length of stay was consistently higher for patients with GF. Similar trends were seen for inpatient costs, although improvements were seen in our entire HCT population over time. In summary, GF remains a significant challenge in pediatric HCT and poses an economic burden on the health care system.

Healthcare utilization and financial impact of acute-graft-versus host disease among children undergoing allogeneic hematopoietic cell transplantation.

The impact of AGVHD on healthcare utilization and cost is not well described. In this retrospective single center cohort study of 240 pediatric patients, we analyzed cost, healthcare utilization and patient outcomes for the first year post-alloHCT. Costs were estimated from charges recorded in the Pediatric Health Information System database and the hospital's accounting system. The overall incidence of grade I-IV aGVHD was 40.4%. The incidence of grade I, grade II, and grade III-IV aGVHD was 6.6%, 16.2%, and 17.5%, respectively. The overall incidence of steroid refractory (SR)-aGVHD was 10.8%. The median number of days of hospitalization in the first year post-alloHCT was significantly higher for patients with aGVHD vs. no aGVHD: 113 days (range: 35-354 days) vs. 63 days (range: 25-298 days), p < 0.001. Patients with SR-aGVHD had increased hospitalization compared with the patients with steroid responsive aGVHD (152.8 ± 66.6days vs. 111.3 ± 59.3 days, p = 0.004), with associated increased alloHCT cost of ~$200,000. On multivariable analysis of risk factor for alloHCT cost, aGVHD, was associated with significantly higher cost ($141,094 [SE = 31247], p < 0.001). In summary, aGVHD and SR-aGVHD is associated with prolonged hospitalization and higher cost and inferior survival among children. Better aGVHD prevention strategies are desperately needed. Despite significant advances, lack of effective salvage regimens for SR-aGVHD remains a major concern.

Exploring mTOR inhibition as treatment for mitochondrial disease.

Leigh syndrome and MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) are two of the most frequent pediatric mitochondrial diseases. Both cause severe morbidity and neither have effective treatment. Inhibiting the mammalian target of rapamycin (mTOR) pathway has been shown in model mice of Leigh syndrome to extend lifespan and attenuate both the clinical and pathological progression of disease. Based on this observation, we treated two children with everolimus, a rapamycin analogue. The child with Leigh syndrome showed sustained benefit, while the child with MELAS failed to respond and died of progressive disease. We discuss possible mechanisms underlying these disparate responses to mTOR inhibition.

Health care utilization and cost among pediatric patients receiving unrelated donor allogeneic hematopoietic cell transplantation.

The costs associated with allogeneic hematopoietic cell transplantation (alloHCT) are high. Differences in costs and healthcare utilization among potential donor sources for alloHCT are not well characterized in pediatric recipients of alloHCT. One potential reason for these high costs could be the donor source of hematopoietic cells. In this retrospective study, inpatient costs, outpatient costs, and markers of healthcare utilization associated with unrelated donor alloHCT for malignant and non-malignant disease were analyzed for 131 pediatric patients during the first year post-transplant, for whom the donor sources were 38% umbilical cord blood (UCB), 14% unmanipulated peripheral blood stem cell (PBSC), 26% bone marrow (BM), and 22% PBSC with CD-34 selection. The median cost per day survived (through day +365) was lowest for patients receiving PBSC with CD-34 selection $926 (322-5316) as compared to UCB $1918 (491-107,93), unmanipulated PBSC $1516 (630-27,516), and BM $1205 (506-11,181) (p = 0.010). For non-malignant alloHCT, UCB had the highest costs per day survived $1530 (491-793) and PBSC with CD-34 selection had the lowest at $482 (322-3092) (p < 0.001). In a multivariable model for costs per day survived, high-risk disease (p = 0.009) and graft failure (p < 0.001) were significantly associated with higher cost and alloHCT between 2010 and 2015 as compared to 2005 and 2009 (p = 0.017) was significantly associated with lower cost per day survived. This study illustrates important differences in cost and healthcare utilization among the different donor sources used for unrelated alloHCT.

Clinical and Economic Impact of Cytomegalovirus Infection among Children Undergoing Allogeneic Hematopoietic Cell Transplantation.

The literature on the impact of cytomegalovirus (CMV)-related hospitalization in pediatric allogeneic hematopoietic cell transplantation (alloHCT) recipients is limited. The aim of this study was to determine utilization and outcomes of CMV-related hospitalization in alloHCT recipients using a single-center clinical database. This was a retrospective study of 240 children aged 3 months to 21 years (median age, 9.5 years) who underwent alloHCT between 2005 and 2016. The impacts of CMV-related length of stay (LOS) and total healthcare costs were quantified. Factors associated with prolonged CMV viremia (>25 days' duration) were also examined. In at-risk patients with CMV infection, the incidence of CMV viremia was 38% (59 of 155), the median time to onset was 33 days (range, 0 to 292 days), and the median time to resolution was 25 days (range, 3 to 48 days; n = 53). CMV infection was associated with a 23.3-day increase in LOS (P = .004) and added hospital costs of $45,443 (P = .162) compared with patients without CMV infection. In multivariable analysis, receipt of alemtuzumab (P = .027) was associated with CMV viremia of >25 days' duration. Our data show that CMV viremia is associated with prolonged LOS and higher hospital costs and indicate the need for improved and cost-effective CMV prevention strategies. Further studies of patient outcomes and costs in pediatric alloHCT recipients is needed.

Pre-irradiation intensive induction and marrow-ablative consolidation chemotherapy in young children with newly diagnosed high-grade brainstem gliomas: report of the "head-start" I and II clinical trials.

BACKGROUND: The dismal outcome in children with high-grade brainstem gliomas (BSG) accentuates the need for effective therapeutic strategies. We investigated the role of intensive, including marrow-ablative, chemotherapy regimens in the treatment of young children with newly-diagnosed high-grade BSG. METHODS: Between 1991-and-2002, 15 eligible children less than 10 years of age with a diagnosis of high-grade BSG were treated on "Head-Start" I and II protocols (HSI and HSII). Treatment included Induction with 4-5 cycles of one of three intensive chemotherapy regimens followed by Consolidation with one cycle of marrow-ablative chemotherapy (thiotepa, carboplatin and etoposide) with autologous hematopoietic cell rescue (AHCR). Irradiation was required for children over 6 years of age or for those with residual tumor at the end of Consolidation. RESULTS: We had two long-term survivors who were found retrospectively to harbor low-grade glial tumors and thus were not included in the survival analysis. Of the remaining 13 patients, the 1-year event-free (EFS) and overall (OS) survival for these children were 31% (95% CI 9-55%) and 38% (95% CI 14-63%), respectively. Median EFS and OS were 6.6 (95% CI 2.7, 12.7) and 8.7 months (95% CI 6.9, 20.9), respectively. Eight patients developed progressive disease during study treatment (seven during Induction and one at the end of Consolidation). Ten children received focal irradiation, five for residual tumor (three following Induction and two following Consolidation) and five due to disease progression. CONCLUSIONS: Children with high-grade BSG did not benefit from this intensive chemotherapy strategy administered prior to irradiation.

Bone Marrow Harvest in Pediatric Sibling Donors: Role of Granulocyte Colony-Stimulating Factor Priming and CD34+ Cell Dose.

To ensure optimal clinical outcomes for patients while retaining adequate protection for donors, the National Marrow Donor Program developed guidelines specifying that up to 20 mL/kg of bone marrow can be harvested from donors. These guidelines, originally developed for unrelated adult donors, are followed in children as well. We studied the impact of granulocyte colony-stimulating factor (G-CSF) priming on the cellular composition of harvested bone marrow, sought to develop an algorithm to optimize bone marrow harvest volume from pediatric matched sibling donors, and studied the impact of CD34+ cell dose on clinical outcomes. We analyzed data from 92 bone marrow harvests and clinical outcomes for 69 sibling recipient-donor duos, The mean age of recipients was 9.85 ± 5.90 years, and that of donors was 11.85 ± 6.36 years. G-CSF priming was not associated with higher yield of CD34+ cells/µL. The median CD34+ cell count obtained from donors was 700 cells/µL (range, 400-1700 cells/µL) in donors age <6 years, 360 cells/µL (range, 100-1100 cells/µL) in donors age 6 to 12 years, and 300 cells/µL (range, 80-800 cells/µL) in donors age >12 years (P < .001). The number of CD34+ cells infused had no impact on traditional clinical outcomes; however, it was significantly related to graft-versus-host disease/relapse/rejection-free survival. Our investigation revealed that ultimately, a CD34+ cell count of approximately 3 to 5 × 106/kg was a threshold beyond which increasing CD34+ cell dose did not impact outcome. In this study, we addressed the broad question of whether harvesting up to 20 mL/kg of bone marrow from a child donor is truly necessary for optimal outcomes in every pediatric case.