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.

The InSight HP3 Penetrator (Mole) on Mars: Soil Properties Derived from the Penetration Attempts and Related Activities

The NASA InSight Lander on Mars includes the Heat Flow and Physical Properties Package HP³ to measure the surface heat flow of the planet. The package uses temperature sensors that would have been brought to the target depth of 3-5 m by a small penetrator, nicknamed the mole. The mole requiring friction on its hull to balance remaining recoil from its hammer mechanism did not penetrate to the targeted depth. Instead, by precessing about a point midway along its hull, it carved a 7 cm deep and 5-6 cm wide pit and reached a depth of initially 31 cm. The root cause of the failure - as was determined through an extensive, almost two years long campaign - was a lack of friction in an unexpectedly thick cohesive duricrust. During the campaign - described in detail in this paper - the mole penetrated further aided by friction applied using the scoop at the end of the robotic Instrument Deployment Arm and by direct support by the latter. The mole tip finally reached a depth of about 37 cm, bringing the mole back-end 1-2 cm below the surface. It reversed its downward motion twice during attempts to provide friction through pressure on the regolith instead of directly with the scoop to the mole hull. The penetration record of the mole was used to infer mechanical soil parameters such as the penetration resistance of the duricrust of 0.3-0.7 MPa and a penetration resistance of a deeper layer ( > 30 cm depth) of 4.9 ± 0.4 MPa . Using the mole's thermal sensors, thermal conductivity and diffusivity were measured. Applying cone penetration theory, the resistance of the duricrust was used to estimate a cohesion of the latter of 2-15 kPa depending on the internal friction angle of the duricrust. Pushing the scoop with its blade into the surface and chopping off a piece of duricrust provided another estimate of the cohesion of 5.8 kPa. The hammerings of the mole were recorded by the seismometer SEIS and the signals were used to derive P-wave and S-wave velocities representative of the topmost tens of cm of the regolith. Together with the density provided by a thermal conductivity and diffusivity measurement using the mole's thermal sensors, the elastic moduli were calculated from the seismic velocities. Using empirical correlations from terrestrial soil studies between the shear modulus and cohesion, the previous cohesion estimates were found to be consistent with the elastic moduli. The combined data were used to derive a model of the regolith that has an about 20 cm thick duricrust underneath a 1 cm thick unconsolidated layer of sand mixed with dust and above another 10 cm of unconsolidated sand. Underneath the latter, a layer more resistant to penetration and possibly containing debris from a small impact crater is inferred. The thermal conductivity increases from 14 mW/m K to 34 mW/m K through the 1 cm sand/dust layer, keeps the latter value in the duricrust and the sand layer underneath and then increases to 64 mW/m K in the sand/gravel layer below.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s11214-022-00941-z.

TMIC-68. EVALUATING FLASH AND CONVENTIONAL DOSE-RATE RADIATION AND IMMUNE RESPONSE WITH SINGLE-CELL SEQUENCING IN DIFFUSE MIDLINE GLIOMA (DMG)

Diffuse Midline Glioma – H3K27M mutant (DMG), is a fatal and inoperable pediatric brain tumor with limited treatment options as radiation provides only temporary reprieve, leaving the median survival between 9-15 months. Conventional dose-rate radiation (2Gray/minute, CONV) has been shown in other cancers to recruit an immune component, however, this has not been studied in DMG. Ultra-high dose-rate radiation given at 90 Gray/second (FLASH), is a novel technique associated with decreased toxicity and effective tumor control. Using a syngeneic model of brainstem DMG, we performed single-cell RNA sequencing on CD45+ immune cells isolated from tumors irradiated with 15Gray using FLASH or CONV, and compared to unirradiated tumor and normal brainstem. Isolation of 33,308 immune cells revealed 17 unique clusters, most abundant of which was microglia (73.8%), present in four distinct subtypes representing a spectrum from homeostatic to activated. In the most activated microglia, both FLASH and CONV showed an enrichment in type 1 interferon (IFN1) pathway scores compared to untreated tumors (p< 0.001 and p< 0.001, respectively). The most differential response was found in macrophages (MAC) and dendritic cells (DC) with a robust enrichment of IFN1 pathway scores for CONV compared to FLASH (p< 0.001, MAC and p< 0.001 DC). FLASH showed an increase in anti-inflammatory MAC markers such as Mrc1, Cd163, and Maf and an enrichment of myeloid-derived suppressor cell (MDSC) signature in monocytes, not seen in CONV (p< 0.001). Finally, we correlated our data with publicly available single-cell data taken from the cerebrospinal fluid of DMG patients treated with anti-GD2 CAR T Cell therapy and found similar inflammatory markers characteristic of our unirradiated murine tumors. In summary, our work is the first to study immune alterations comparing different dose-rates of radiation with single-cell resolution in DMG, highlighting the potential for combining radiation and immunotherapy in these tumors.

BIOM-49. A PILOT STUDY OF CEREBROSPINAL FLUID EXOSOMAL SMALL RNA-SEQUENCING IN PEDIATRIC MEDULLOBLASTOMA PATIENTS ON THE NEXT CONSORTIUM “HEAD START” 4 PROTOCOL

BACKGROUND

Head Start 4 is a randomized clinical trial to determine whether dose-intensive tandem consolidation, compared with a single cycle, with autologous hematopoietic progenitor cell rescue provides a survival benefit in pediatric patients with medulloblastoma or other embryonal tumors. The trial incorporates upfront molecular subgrouping and non-mandatory, prospective blood and cerebrospinal fluid (CSF) collection. This pilot study aimed to identify exosomal non-coding RNAs (exo-ncRNAs) that might serve as novel diagnostic and/or treatment response biomarkers.

METHODS

CSF(1-2mLs) from 11 controls (non-tumor) and 27 medulloblastoma participants including 23 obtained at baseline, 22 at the end of induction, 3 post-consolidation, and 4 relapse time points, were profiled. Exosome isolation and small RNA-sequencing were performed by System Biosciences. Differential gene expression (DGE) was performed in R (DESeq2). Variations in gene expression profiles between samples were visualized using principal component analysis.

RESULTS

After limiting to ncRNAs with expression of 2 counts per million in 50% or more of the samples in each comparison, ~9,500 ncRNAs were detected. DGE analyses revealed 118 ncRNAs with log2 fold change(FC) >2 and 1 ncRNA with log2FC< -2 in baseline CSF samples compared to controls. In contrast, 11 ncRNAs(log2FC >2) and 1 ncRNA(log2FC< -2) were detected in end of induction CSF samples compared to controls. Comparing end of induction to baseline CSF samples accounting for paired samples, 0 ncRNAs(log2FC >2) and 52 ncRNAs(log2FC< -2) were detected.

CONCLUSIONS

Overall, our data indicate that exosomal small RNA-sequencing of limited CSF volumes is feasible. Differential expression and distinct clustering between tumor baseline samples compared to non-tumor controls was observed. CSF-derived exo-ncRNAs at end of induction also demonstrated “normalization” of ncRNA profiles, signifying CSF biomarkers may serve a role in diagnosis and molecular response assessment. A comprehensive analysis including multi-marker predictive model development and molecular subgrouping will be undertaken at completion of study enrollment.

EPID-07. Outcome disparities in children, adolescents and young adults with medulloblastoma: A population-based analysis

Medulloblastoma (MB) is the most common high-grade primary pediatric brain tumor. Recent registry-based studies in children with central nervous system (CNS) tumors have demonstrated that survival outcomes differ by race/ethnicity in multivariable analyses, with Hispanic patients having highest hazard of death overall. To investigate this finding in MB patients, we examined survival in children (0-14 years) and adolescent/young adults (15-39 years) with MB from 2007-2016 in the 2018 Surveillance Epidemiology and End Results Program database, using Kaplan Meier analysis, log-rank test and Cox proportional hazard ratios (HR) with 95% confidence intervals (CI). Race and ethnicity were categorized according to the U.S. Census, with Hispanic ethnicity (yes/no) analyzed separately from race (Black, White, Asian, Other). Among 1612 patients, 81% were White, 9% were Black, 8% were Asian or Pacific Islander, and 2% were from “other” or unknown racial groups. 28% of the cohort was of Hispanic ethnicity. Univariate analysis found that Black patients had a significantly higher hazard of death than White patients (HR=1.55, CI: 1.16 – 2.08, p=0.003). In contrast, Hispanic ethnicity was not significantly associated with outcome (HR=0.98, CI: 0.79-1.21, p=0.8). Medicaid or no insurance (vs. private) were each significantly associated with higher risk of death; Medicaid (HR =1.23, CI = 1.01 - 1.51, p=0.041); Uninsured (HR=2.07, CI=1.41-3.02, p=<0.001). Of the treatment modalities analyzed, patients who received neither chemotherapy nor radiation experienced higher hazard of death than patients who received both treatments (HR=3.63, CI 2.78-4.76, p=<0.001). Consistent with observations in other cancers, racial disparities are observed in patients with MB, with Black race conferring increased risk of death. Public insurance was also significantly associated with death, as was not receiving combined-modality therapy. Further work is needed to understand the multilevel factors impacting diagnosis, treatment and outcome among children and AYAs with MB and prospective studies are warranted.

DDEL-07. A Phase I study examining the feasibility of intermittent convection-enhanced delivery (CED) of MTX110 for the treatment of children with newly diagnosed diffuse midline gliomas (DMGs)

Histone deacetylase inhibitors have been found preclinically to be among the most active agents against DMGs, however, they are clinically ineffective with systemic delivery due to blood brain barrier limitations and toxicity. Using a repurposed device (implantable subcutaneous pump connected with a catheter directly implanted into the pons/thalamus) we are performing a phase I, standard 3 + 3 dose escalation study to investigate the safety and feasibility of repeated infusions of MTX110 (Midatech Pharma), a water-soluble formulation of panobinostat, via CED. Eligible patents are between 3 and 18 years of age with newly diagnosed DMG following radiation therapy, without hemorrhage or cyst in the tumor, and having intact organ function. Following tumor biopsy and device implantation, patients receive two 48-hour-infusion pulses 7 days apart of MTX110 (30, 60, or 90 mM). The infusion pump is prefilled with MTX110 (and gadolinium for co-infusion to serve as a surrogate for drug distribution) and administered using the wireless N’Vision clinical programmer at a rate of 0.2 mL/hr. Seven patients (30 mM group, n=3 and 60 mM group, n=4) have been treated with the MTX110 infusate. All but one patient had adequate tumor coverage as measured by co-infused gadolinium on MRI. One patient suffered a severe adverse event related to the infusion and tumor anatomy. Four patients had Grade 2 transient neurological deficits related to biopsy (n=1) and the infusion (n=3). In a follow up period of 12-22 months from diagnosis, progression free survival ranges from 8 to 20 months. With one objective response, 3 patients remain alive (2 without progression, both at 12 months, and 1 with progressive disease, at 22 months post diagnosis). Three patients are expected to be treated at 90 mM level. Using MTX110, we demonstrated the safety and feasibility of repeated drug infusion by CED in DMG patients.

MODL-25. Radiation and focused ultrasound–mediated blood–brain barrier opening for DMG: safety and feasibility of combinatorial therapy

Diffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic therapeutic strategies have been unsuccessful to date and radiotherapy (RT) remains the standard of care. A central impediment to systemic therapy is the blood-brain barrier (BBB), which precludes drug delivery to the tumor site. Focused ultrasound (FUS) with intravenous microbubbles can transiently and non-invasively circumvent the BBB to enhance drug delivery. Nevertheless, it remains unclear whether FUS is safe at the brainstem in combination with clinical doses of RT. In this study, we hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT. To establish a safety timeline, we administered FUS to the brainstem of nontumor bearing mice concurrent with or adjuvant to radiation; then, we validated our findings in a syngeneic orthotopic xenograft DMG model which received repeated sonication concurrent with RT. Male B6 (Cg)-Tyrc-2J/J albino mice received intracranial injection of 4423 mouse DMG cells (PDGFB+, H3.3K27M, p53−/−) at a location posterior and lateral to the lambda. A clinical RT dose of 39 Gy in 13 fractions was delivered to the brainstem with the Small Animal Radiation Research Platform (SARRP) or the XRAD-320 irradiator. FUS was administered with a 0.5 MHz transducer, and both BBBO and tumor volume were monitored with MRI. FUS-mediated BBBO in nontumor bearing mice receiving RT did not affect cardiorespiratory rate, motor function, and tissue integrity. Moreover, tumor bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy over 13 fractions offered local control, although disease progression occurred in all animals approximately 3-4 weeks post-RT. Ultimately, repeated FUS-mediated BBB opening concurrent with RT is safe and feasible. In our brainstem DMG model, relapse occurs, making it ideal for future tests of combinatorial RT and FUS-mediated drug delivery.

DIPG-45. Radiation induces a robust interferon response in Diffuse Midline Glioma (DMG), improving the potential for combination immunotherapy

Diffuse Midline Glioma (DMG), H3K27M altered, confers a dismal survival of 9-15 months and has a non-inflammatory tumor immune microenvironment (TIME). Radiation therapy (RT) is the mainstay treatment for DMG and has been shown in other cancers to recruit an immune component. However, the effect of RT on the DMG TIME has not been explored. In a syngeneic murine model of pontine DMG (PDGFB+, H3.3K27M, p53−/−), mice were treated with single fraction 15Gy RT or sham control, four mice per group. We performed single cell sequencing after CD45 isolation to evaluate the TIME 4 days post RT and compare to untreated tumor (sham control). Unsupervised clustering of 14,848 CD45+ cells revealed 16 immune cell subsets, most abundantly microglia at 75% of cells, with four subtypes representing a spectrum of homeostatic to activated. Microglia from RT are more concentrated in the activated subtypes with an upregulation of interferon response (i.e. Isg15, Ifit3) compared to untreated tumor with an increase in several interferon pathways using REACTOME. Consistent with RT response, RT treated tumors have increase in cell cycle regulatory genes such as Cdkn1a, across all clusters. In non-resident myeloid cells, compared to untreated tumor, RT is associated with a robust upregulation of interferon response genes in both macrophages (Isg15 Fold Change (FC) 2.30; Ifit1 FC 1.64; Ifit3 FC 2.02; Cxcl10 FC 2.29) and dendritic cells (Isg15 FC 2.67; Ifit1 FC 1.72; Ifit3 FC 2.06; Cxcl10 FC 1.50). We also find differential expression of immune checkpoints in RT-treated versus untreated tumor with decreased expression of Lag3, Tim3 (Havcr2), and Csf1R and increased expression of Cd47, Sirpa and Gitr (Tnfrsf18) post RT. In summary, RT stimulates a pro-inflammatory TIME response and alters immune checkpoints in DMG, highlighting the potential for combining RT and immunotherapy in these tumors.

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.

DDEL-07. A PHASE I STUDY EXAMINING THE FEASIBILITY OF INTERMITTENT CONVECTION-ENHANCED DELIVERY (CED) OF MTX110 FOR THE TREATMENT OF CHILDREN WITH NEWLY DIAGNOSED DIFFUSE MIDLINE GLIOMAS

Convection-enhanced delivery (CED, the infusion of drugs under controlled pressure to the brain parenchyma via targeted micro-catheters, allows accurate anatomical targeting and delivery of higher (therapeutic) drug concentrations through clinically relevant volumes of brain tissue or tumor. Histone deacetylase inhibitors have been found in vitro to be the most active agents against Diffuse Midline Gliomas (DMGs) Using a novel device (implantable subcutaneous pump connected with catheter directly implanted into the pons/thalamus) we are performing a Phase I safety study of repeated infusions of MTX110 (MTX110, Midatech) in a dose escalation manner. Eligible patients include 3–18 years of age with newly diagnosed DMGs following radiation therapy without evidence of hemorrhage or cysts with intact organ function. Patients undergo a tumor biopsy and a single catheter (Spetzler lumbar shunt catheter, Integra, Plainsboro, NJ) is placed stereotactically into the geometric center of the tumor. A second catheter is inserted subcutaneously with the distal tubing connected to the infusion pump, (SynchroMed II (Medtronic)), also inserted subcutaneously. The infusion pump is prefilled with MTX110 and administered using wireless N’Vison Clinical programmer into two 24-hour infusions, consisting of 20 hours of drug infusions at 0.2mL/hr. The pulse is completed 7 days later. This is a dose escalation study with the infusate consisting of gadolinium and MTX110 (30, 60, or 90 microM). The study describing the first use in children of this device for direct-to-tumor drug delivery is open to recruitment (January 2020) and the preliminary data will be available for presentation by June 2020.

MODL-09. FEASIBILITY OF ACUTE SLICE CULTURE-SINGLE CELL SEQUENCING DRUG SCREENING AS A TOOL TO SELECT THERAPY FOR CHILDREN WITH RELAPSED BRAIN TUMORS

Children with relapsed brain tumors are less responsive to treatment. These children often receive therapies without having any robust predictive method of potential benefit. Acute slice culturing(ASC) is a methodology permitting freshly operated tumor to undergo a culturing process preserving the tumor’s micro-environment. With the current study, we investigated the feasibility of obtaining therapeutically meaningful data in a timely manner (3–5 days), performing direct drug testing and single cell sequencing using ASC. Previously, we have combined ex vivo slices of intact, patient-derived Glioblastoma tissue with single-cell RNA-seq for small-scale drug screening and assessment of patient and cell type-specific drug responses. We generated slices from preclinical mouse glioma models and surgical specimens from adult Glioblastoma patients, as well as from children with relapsed Ependymomas, Medulloblastomas, and Gliomas. We demonstrated that these acute slices preserved both the tumor heterogeneity and tumor microenvironment observed in single-cell RNA-seq of cells directly isolated from tumor tissue. Testing drug responses, we then treated tissue slices from the Glioblastoma mouse models and different patients with multiple drugs and combinations. This technique allowed us to identify drug-induced transcriptional responses in specific subpopulations of tumor cells, patient-specific drug sensitivities, and drug effects conserved in both mouse and human tumors. Preliminary data suggests that we can apply this procedure within 5–7 days and provide real-time drug screening/single cell sequencing ASC results to Recurrent/ Progressive pediatric Low-Grade Gliomas, High Grade Gliomas, Ependymomas and Medulloblastomas.

Survival in adult and pediatric patients with medulloblastoma: A 2018 SEER-based analysis

e14529

Background: Medulloblastoma (MB) is a malignant neuroectodermal tumor accounting for 30% of pediatric and only 1% of adult brain tumors. In previous studies comparing survival in pediatric and adult MB from the National Cancer Institute Surveillance Epidemiology and End Results (SEER) database no difference has been found. However, diagnostic subgroup analyses have been limited. Methods: We examined survival in children (age 0-19) and adults (20-79) coded as MB in the 2018 SEER database (2000-2016). We used Kaplan Meier analysis, log-rank test and Cox proportional hazard ratios (HR) with 95% confidence intervals (CI). MB in SEER-18 is defined as ICD-O-3 histology codes 9470–9474 (n = 1,728). ICD 9473, supratentorial PNET (sPNET, n = 97) is biologically distinct and therefore it was analyzed separately. Results: We found that 5-year survival for MB, excluding sPNET, was similar in children (n = 1,091, 75.3%) and adults (n = 488, 79.1%) (HR = 0.97, CI: 0.79 – 1.17, p = 0.50). Furthermore, subtype analyses showed no survival difference comparing adults and children with desmoplastic nodular MB (n = 222, p = 0.09), large cell MB (n = 73, p = 0.46), or MB NOS (n = 1330, p = 0.10). Yet, children with sPNET had improved 5-year survival (n = 65, 72.3%) compared to adults (n = 29, 51.7%) (HR = 2.0, CI: 1.10 – 3.92; p = 0.02,). These findings indicate that while survival in patients with MB is similar across age groups, children with sPNET have improved outcomes. Conclusions: In summary, 2018 SEER data for MB continue to show no survival difference between adults and children, suggesting adult patients could appropriately be entered on pediatric MB treatment protocols. Further analyses of the 2018 data are ongoing adjusting for sex, race, and treatment (chemotherapy or radiation). For sPNET, the apparent improved outcomes for children merit further detailed investigation and will be re-evaluated using the new 2016 World Health Organization classification.

Safety of hematopoietic cell infusion in children with malignant and non-malignant diseases

HPC infusions have been associated with a variety of adverse events related to either patient or HPC product-related factors. Studies documenting infusion-related AEs in children are limited. We reviewed HPC infusion records in 354 children. Infusion-related adverse events were classified as follows: grade 0-absent, grade I-mild, grade II-moderate, grade III-severe, grade IV-life-threatening, and grade V-death. The percentage of patients with grade 0, I, and II-IV AEs was as follows: 0 = 67%, I = 23.4%, and II-V = 9.6% (one patient had fatal anaphylactic reaction to dimethyl sulfoxide). The incidence of grade II-IV hypertension was 7.1%. There was a higher incidence of AEs with infusion of allogeneic bone marrow versus allogeneic PBSCs (47.4% vs 25.3%, P = .001). Cryopreserved products had a lower incidence of infusion-associated AEs compared with fresh HPC products (24% vs 39.4%, P = .003). Allogeneic HPC infusion volume (>100 mL) was a significant risk factor for infusion-associated AEs (P < .001). Patients >10 years who received autologous HPC infusions had higher risk of AEs when compared to patients <10 years (P = .01). Our study demonstrated that despite a high incidence of infusion-associated hypertension, HPC infusion is relatively safe in children. Investigating strategies to optimize management of hypertension in the setting of HPC infusion is warranted.

Bacterial bloodstream infections in pediatric allogeneic hematopoietic stem cell recipients before and after implementation of a central line-associated bloodstream infection protocol: A single-center experience

INTRODUCTION

There are only few reports describing the influence of central line-associated bloodstream infection (CLABSI) prevention strategies on the incidence of bacterial bloodstream infections (BBSIs).

METHODS

We performed a retrospective cohort study among pediatric recipients of allogeneic hematopoietic stem cell transplantation (allo-HCT) to assess potential changes in BBSI rates during 3 time periods: pre-CLABSI prevention era (era 1, 2004-2005), CLABSI prevention implementation era (era 2, 2006-2009), and maintenance of CLABSI prevention era (era 3, 2010-2012). BBSI from day 0-365 following allo-HCT were studied. The comparison of person-years incidence rates among different periods was carried out by Poisson regression analysis.

RESULTS

The mean age of patients was 10.0 years. During the study period, 126 (65%) of 190 patients had at least a single BBSI. From day 0-30, day 31-100, day 101-180, and day 181-365, 20%, 28%, 30%, and 17% of patients, respectively, experienced BBSIs. The rate of Staphylococcus epidermidis and gram-negative pathogens significantly declined from 3.16-0.93 and 6.32-2.21 per 100 person-months during era 1 and era 3, respectively (P = .001).

CONCLUSIONS

Patients undergoing allo-HCT during era 3 were associated with decreased risk of BBSI (P = .012). Maintenance of CLABSI protocols by nursing staff and appropriate education of other care providers is essential to lower incidence of BBSI in this high-risk population, and further strategies to decrease infection burden should be studied.

Outcome of young children with high-grade glioma treated with irradiation-avoiding intensive chemotherapy regimens: Final report of the Head Start II and III trials

PURPOSE

To report the final analysis of survival outcomes for children with newly diagnosed high-grade glioma (HGG) treated on the "Head Start" (HS) II and III protocols with chemotherapy and intent to avoid irradiation in children <6 years old.

PATIENTS AND METHODS

Between 1997 and 2009, 32 eligible children were enrolled in HS II and III with anaplastic astrocytoma (AA, n = 19), glioblastoma multiforme (GBM, n = 11), or other HGG (n = 2). Central pathology review was completed on 78% of patients. Patients with predominantly brainstem tumors were excluded. Patients were to be treated with single induction chemotherapy regimen C, comprising four cycles of vincristine, carboplatin, and temozolomide. Following induction, patients underwent marrow-ablative chemotherapy and autologous hematopoietic cell rescue. Irradiation was used for patients with residual tumor after consolidation or >6 years old or at the time of tumor progression.

RESULTS

The 5-year event-free survival (EFS) and overall survival (OS) for all HGG patients were 25 ± 8% and 36 ± 9%, respectively. The EFS at 5 years for patients with AA and GBM were 24 ± 11% and 30 ± 16%, respectively (P = 0.65). The OS at 5 years for patients with AA and GBM was 34 ± 12% and 35 ± 16%, respectively (P = 0.83). Children <36 months old experienced improved 5-year EFS and OS of 44 ± 17% and 63 ± 17%, compared with children 36-71 months old (31 ± 13% and 38 ± 14%) and children >72 months old (0% and 13 ± 12%).

CONCLUSIONS

Irradiation-avoiding treatment strategies should be evaluated further in young children with HGG given similar survival rates to older children receiving standard irradiation-containing therapies.

Health-related quality of life after allogeneic hematopoietic stem cell transplantation for sickle cell disease

Sickle cell disease (SCD) is a hereditary hemoglobinopathy that affects over 100,000 people in the United States. Patients with SCD are known to experience suboptimal health-related quality of life (HRQoL). In addition to the physical manifestations of SCD, psychological and social stress, along with academic difficulties, secondary to the chronicity of the disease and its complications often affect patients with SCD. Although medical therapy of SCD has improved, allogeneic hematopoietic cell transplantation (allo-HCT) remains the only curative therapy. The objective of this study was to measure HRQoL before and after allo-HCT by assessing physical, psychological, and social functioning in patients with SCD who have undergone reduced-toxicity conditioning (busulfan/fludarabine/alemtuzumab) followed by allo-HCT. Patients < 21 years of age undergoing allo-HCT (matched siblings and unrelated donors) for SCD and their primary caregiver were enrolled using either the English or Spanish version of the PedsQoL 4.0. Data were collected at 3 time points: before allo-HCT and on days 180 and 365 after allo-HCT. The change in HRQoL from baseline was assessed with unadjusted and adjusted mixed-effects models in which subjects were treated as random effects, and variance component structure was used. Seventeen patients and 23 primary caregivers were enrolled and reported a mean overall HRQoL of 66.05 (SD, 15.62) and 72.20 (SD, 15.50) at baseline, respectively. In the patient-reported analysis with adjusted mixed-effects models, the estimated improvements in overall HRQoL were 4.45 (SE, 4.98; P = .380) and 16.58 (SE, 5.06; P = .003) at 180 and 365 days, respectively, after allo-HCT. For parent-reported overall HRQoL, the estimated improvements were 1.57 (SE, 4.82; P = .747) and 9.28 (SE, 4.62; P = .053) at 180 and 365 days, respectively, after allo-HCT. Similar results were found across the physical, social, and emotional HRQoL domains with mixed-effects models after adjustment of demographic and medical variables. In addition to the alleviation of clinical manifestations of SCD, these patients demonstrated significant improvement in most aspects of HRQoL by 1 year after allo-HCT. These data represent the trajectory of HRQoL during the initial year of follow-up within this population and should be integrated into the decision-making process when considering allo-HCT in patients with SCD.

Impact of palifermin on incidence of oral mucositis and healthcare utilization in children undergoing autologous hematopoietic stem cell transplantation for malignant diseases

Palifermin has been demonstrated to decrease the incidence of severe oral mucositis in adults following TBI containing conditioning regimens prior to AHSCT. The impact of palifermin on the incidence of oral mucositis in children undergoing AHSCT has never been studied. We compared the effect of palifermin on the incidence of oral mucositis and supportive care in 58 children undergoing myeloablative AHSCT; 25 children received palifermin and 33 children did not receive palifermin (control arm). Oral mucositis was graded as per WHO criteria. The demographic characteristics were comparable between the two arms. Results comparing the palifermin vs. control arm showed that the incidence of grade III-IV oral mucositis was 20% vs. 42.4% (p = 0.072). The number of days patients received patient-controlled analgesia and total parenteral nutrition in the palifermin vs. control arm were 8.80 ± 8.39 vs. 8.30 ± 8.54 (p = 0.826) and 13.52 ± 11.32 vs. 11.55 ± 9.63 (p = 0.484), respectively. The average length of hospitalization in the palifermin vs. control arm was 31.44 ± 7.42 vs. 28.61 ± 10.38 (p = 0.252), respectively. In this study, we were unable to demonstrate a statistical difference in the incidence of oral mucositis and other supportive care needs or a decrease in hospital stay between the two arms.

Convection-enhanced delivery of topotecan into diffuse intrinsic brainstem tumors in children

Convection-enhanced delivery (CED) for the treatment of malignant gliomas is a technique that can deliver chemotherapeutic agents directly into the tumor and the surrounding interstitium through sustained, low-grade positive-pressure infusion. This allows for high local concentrations of drug within the tumor while minimizing systemic levels that often lead to dose-limiting toxicity. Diffuse intrinsic pontine gliomas (DIPGs) are universally fatal childhood tumors for which there is currently no effective treatment. In this report the authors describe CED of the topoisomerase inhibitor topotecan for the treatment of DIPG in 2 children. As part of a pilot feasibility study, the authors treated 2 pediatric patients with DIPG. Stereotactic biopsy with frozen section confirmation of glial tumor was followed by placement of bilateral catheters for CED of topotecan during the same procedure. The first patient underwent CED 210 days after initial diagnosis, after radiation therapy and at the time of tumor recurrence, with a total dose of 0.403 mg in 6.04 ml over 100 hours. Her Karnofsky Performance Status (KPS) score was 60 before CED and 50 posttreatment. Serial MRI initially demonstrated a modest reduction in tumor size and edema, but the tumor progressed and the patient died 49 days after treatment. The second patient was treated 24 days after the initial diagnosis prior to radiation with a total dose of 0.284 mg in 5.30 ml over 100 hours. Her KPS score was 70 before CED and 50 posttreatment. Serial MRI similarly demonstrated an initial modest reduction in tumor size. The patient subsequently underwent fractionated radiation therapy, but the tumor progressed and she died 120 days after treatment. Topotecan delivered by prolonged CED into the brainstem in children with DIPG is technically feasible. In both patients, high infusion rates (> 0.12 ml/hr) and high infusion volumes (> 2.8 ml) resulted in new neurological deficits and reduction in the KPS score, but lower infusion rates (< 0.04 ml/hr) were well tolerated. While serial MRI showed moderate treatment effect, CED did not prolong survival in these 2 patients. More studies are needed to improve patient selection and determine the optimal flow rates for CED of chemotherapeutic agents into DIPG to maximize safety and efficacy. Clinical trial registration no.: NCT00324844.