A Multifaceted Intervention to Improve Teamwork on an Inpatient Pediatric Neurosurgery Service

BACKGROUND

Increased safety reports related to interprofessional teamwork on an acute care unit at a quaternary children's hospital prompted a teamwork-focused improvement effort on the pediatric neurosurgery service.

METHODS

An interprofessional workgroup was formed and met twice monthly throughout the project. A survey using modified validated items was disseminated to pediatric neurosurgery nurses, advanced practice providers (APPs), and physicians in March 2021 to identify opportunities for improvement. Structured debriefs on survey results promoted discourse on teamwork. The researchers implemented two interventions: (1) nursing-centered interprofessional education and (2) a rounding checklist before redistributing the survey in December 2021.

RESULTS

Baseline and follow-up survey response rates were 84.1% (58/69) and 71.4% (50/70), respectively. Nurses at baseline perceived lower teamwork scores for 12 items compared to physicians and APPs (p < 0.05). Nurse perceptions improved after interventions in: "using 'we' rather than 'they'" (21.3% vs. 51.2% agree, p = 0.003), "I am confident that this team works effectively" (46.8% vs. 80.5%, p = 0.001), "shared understanding of each other's role on the team" (48.9% vs. 73.2% agree, p = 0.02), and "getting others on the team to listen" (46.8% vs. 75.6%, p = 0.004). Mean teamwork effectiveness improved from 4.12 to 5.25 (out of 7; p < 0.0001). Nurses ranked three interventions as most effective: interprofessional training (35/41, 85.4%), educational clinical pearls (14/41, 34.1%), and structured opportunities to discuss teamwork (10/41, 24.4%).

CONCLUSION

Interprofessional training, a teamwork survey, and structured debriefing improved nurse perceptions of teamwork. Interventions targeting social components of change can improve teamwork even without process changes.

Promoting diversity in neurosurgery through a virtual symposium

OBJECTIVE

The rates of women and underrepresented racial and ethnic minority (UREM) students successfully matching into neurosurgical residency are extremely low and do not reflect the makeup of the general population. As of 2019, only 17.5% of neurosurgical residents in the United States were women, 4.95% were Black or African American, and 7.2% were Hispanic or Latinx. Earlier recruitment of UREM students will help to diversify the neurosurgical workforce. Therefore, the authors developed a virtual educational event for undergraduate students entitled "Future Leaders in Neurosurgery Symposium for Underrepresented Students'' (FLNSUS). The primary objectives of the FLNSUS were to expose attendees to 1) neurosurgeons from diverse gender, racial, and ethnic backgrounds; 2) neurosurgical research; 3) opportunities for neurosurgical mentorship; and 4) information about life as a neurosurgeon. The authors hypothesized that the FLNSUS would increase student self-confidence, provide exposure to the specialty, and reduce perceived barriers to a neurosurgical career.

METHODS

To measure the change in participant perceptions of neurosurgery, pre- and postsymposium surveys were administered to attendees. Of the 269 participants who completed the presymposium survey, 250 participated in the virtual event and 124 completed the postsymposium survey. Paired pre- and postsurvey responses were used for analysis, yielding a response rate of 46%. To assess the impact of participant perceptions of neurosurgery as a field, pre- and postsurvey responses to questions were compared. The change in response was analyzed, and a nonparametric sign test was performed to check for significant differences.

RESULTS

According to the sign test, applicants showed increased familiarity with the field (p < 0.001), increased confidence in their abilities to become neurosurgeons (p = 0.014), and increased exposure to neurosurgeons from diverse gender, racial, and ethnic backgrounds (p < 0.001 for all categories).

CONCLUSIONS

These results reflect a significant improvement in student perceptions of neurosurgery and suggest that symposiums like the FLNSUS may promote further diversification of the field. The authors anticipate that events promoting diversity in neurosurgery will lead to a more equitable workforce that will ultimately translate to enhanced research productivity, cultural humility, and patient-centered care in neurosurgery.

Longitudinal Alterations of Cerebral Blood Flow in High-Contact Sports

OBJECTIVE

Repetitive head trauma is common in high-contact sports. Cerebral blood flow (CBF) can measure changes in brain perfusion that could indicate injury. Longitudinal studies with a control group are necessary to account for interindividual and developmental effects. We investigated whether exposure to head impacts causes longitudinal CBF changes.

METHODS

We prospectively studied 63 American football (high-contact cohort) and 34 volleyball (low-contact controls) male collegiate athletes, tracking CBF using 3D pseudocontinuous arterial spin labeling magnetic resonance imaging for up to 4 years. Regional relative CBF (rCBF, normalized to cerebellar CBF) was computed after co-registering to T1-weighted images. A linear mixed effects model assessed the relationship of rCBF to sport, time, and their interaction. Within football players, we modeled rCBF against position-based head impact risk and baseline Standardized Concussion Assessment Tool score. Additionally, we evaluated early (1-5 days) and delayed (3-6 months) post-concussion rCBF changes (in-study concussion).

RESULTS

Supratentorial gray matter rCBF declined in football compared with volleyball (sport-time interaction p = 0.012), with a strong effect in the parietal lobe (p = 0.002). Football players with higher position-based impact-risk had lower occipital rCBF over time (interaction p = 0.005), whereas players with lower baseline Standardized Concussion Assessment Tool score (worse performance) had relatively decreased rCBF in the cingulate-insula over time (interaction effect p = 0.007). Both cohorts showed a left-right rCBF asymmetry that decreased over time. Football players with an in-study concussion showed an early increase in occipital lobe rCBF (p = 0.0166).

INTERPRETATION

These results suggest head impacts may result in an early increase in rCBF, but cumulatively a long-term decrease in rCBF. ANN NEUROL 2023;94:457-469.

Microstructural Alterations in Tract Development in College Football and Volleyball Players: A Longitudinal Diffusion MRI Study

BACKGROUND AND OBJECTIVES

Repeated impacts in high-contact sports such as American football can affect the brain's microstructure, which can be studied using diffusion MRI. Most imaging studies are cross-sectional, do not include low-contact players as controls, or lack advanced tract-specific microstructural metrics. We aimed to investigate longitudinal changes in high-contact collegiate athletes compared with low-contact controls using advanced diffusion MRI and automated fiber quantification.

METHODS

We examined brain microstructure in high-contact (football) and low-contact (volleyball) collegiate athletes with up to 4 years of follow-up. Inclusion criteria included university and team enrollment. Exclusion criteria included history of neurosurgery, severe brain injury, and major neurologic or substance abuse disorder. We investigated diffusion metrics along the length of tracts using nested linear mixed-effects models to ascertain the acute and chronic effects of subconcussive and concussive impacts, and associations between diffusion changes with clinical, behavioral, and sports-related measures.

RESULTS

Forty-nine football and 24 volleyball players (271 total scans) were included. Football players had significantly divergent trajectories in multiple microstructural metrics and tracts. Longitudinal increases in fractional anisotropy and axonal water fraction, and decreases in radial/mean diffusivity and orientation dispersion index, were present in volleyball but absent in football players (all findings |T-statistic|> 3.5, p value <0.0001). This pattern was present in the callosum forceps minor, superior longitudinal fasciculus, thalamic radiation, and cingulum hippocampus. Longitudinal differences were more prominent and observed in more tracts in concussed football players (n = 24, |T|> 3.6, p < 0.0001). An analysis of immediate postconcussion scans (n = 12) demonstrated a transient localized increase in axial diffusivity and mean/radial kurtosis in the uncinate and cingulum hippocampus (|T| > 3.7, p < 0.0001). Finally, within football players, those with high position-based impact risk demonstrated increased intracellular volume fraction longitudinally (T = 3.6, p < 0.0001).

DISCUSSION

The observed longitudinal changes seen in football, and especially concussed athletes, could reveal diminished myelination, altered axonal calibers, or depressed pruning processes leading to a static, nondecreasing axonal dispersion. This prospective longitudinal study demonstrates divergent tract-specific trajectories of brain microstructure, possibly reflecting a concussive and repeated subconcussive impact-related alteration of white matter development in football athletes.

Factors Associated with Transfer Distance from Birth Hospital to Repair Hospital for First Surgical Repair among Infants with Myelomeningocele in California

OBJECTIVE

 The objective of our study was to examine factors associated with distance to care for first surgical repair among infants with myelomeningocele in California.

STUDY DESIGN

 A total of 677 eligible cases with complete geocoded data were identified for birth years 2006 to 2012 using data from the California Perinatal Quality Care Collaborative linked to hospital and vital records. The median distance from home to birth hospital among eligible infants was 9 miles, and from birth hospital to repair hospital was 15 miles. We limited our analysis to infants who lived close to the birth hospital, creating two study groups to examine transfer distance patterns: "lived close and had a short transfer" (i.e., lived <9 miles from birth hospital and traveled <15 miles from birth hospital to repair hospital; n = 92), and "lived close and had a long transfer" (i.e., lived <9 miles from birth hospital and traveled ≥15 miles from birth hospital to repair hospital; n = 96). Log-binomial regression was used to estimate crude and adjusted risk ratios (aRRs and 95% confidence intervals (CIs). Selected maternal, infant, and birth hospital characteristics were compared between the two groups.

RESULTS

 We found that low birth weight (aRR = 1.44; 95% CI = 1.04, 1.99) and preterm birth (aRR = 1.41; 95% CI = 1.01, 1.97) were positively associated, whereas initiating prenatal care early in the first trimester was inversely associated (aRR = 0.64; 95% CI = 0.46, 0.89) with transferring a longer distance (≥15 miles) from birth hospital to repair hospital. No significant associations were noted by maternal race-ethnicity, socioeconomic indicators, or the level of hospital care at the birth hospital.

CONCLUSION

 Our study identified selected infant factors associated with the distance to access surgical care for infants with myelomeningocele who had to transfer from birth hospital to repair hospital. Distance-based barriers to care should be identified and optimized when planning deliveries of at-risk infants in other populations.

KEY POINTS

· Low birth weight predicted long hospital transfer distance.. · Preterm birth was associated with transfer distance.. · Prenatal care was associated with transfer distance..

The children's brain tumor network (CBTN) - Accelerating research in pediatric central nervous system tumors through collaboration and open science

Pediatric brain tumors are the leading cause of cancer-related death in children in the United States and contribute a disproportionate number of potential years of life lost compared to adult cancers. Moreover, survivors frequently suffer long-term side effects, including secondary cancers. The Children's Brain Tumor Network (CBTN) is a multi-institutional international clinical research consortium created to advance therapeutic development through the collection and rapid distribution of biospecimens and data via open-science research platforms for real-time access and use by the global research community. The CBTN's 32 member institutions utilize a shared regulatory governance architecture at the Children's Hospital of Philadelphia to accelerate and maximize the use of biospecimens and data. As of August 2022, CBTN has enrolled over 4700 subjects, over 1500 parents, and collected over 65,000 biospecimen aliquots for research. Additionally, over 80 preclinical models have been developed from collected tumors. Multi-omic data for over 1000 tumors and germline material are currently available with data generation for > 5000 samples underway. To our knowledge, CBTN provides the largest open-access pediatric brain tumor multi-omic dataset annotated with longitudinal clinical and outcome data, imaging, associated biospecimens, child-parent genomic pedigrees, and in vivo and in vitro preclinical models. Empowered by NIH-supported platforms such as the Kids First Data Resource and the Childhood Cancer Data Initiative, the CBTN continues to expand the resources needed for scientists to accelerate translational impact for improved outcomes and quality of life for children with brain and spinal cord tumors.

STEM-15. THERAPY-INDUCED CHANGES BY BRAF AND MEK INHIBITORS IN BRAF V600E-MUTATED GLIOMA MODELS PROVIDE POTENTIAL NOVEL THERAPEUTIC OPPORTUNITIES

Combinations of the MEK inhibitor trametinib, and BRAF inhibitor dabrafenib (BRAFi+MEKi) show rapid and sustained responses in patients with BRAF V600E-mutated low-grade glioma, but tumor rebound after treatment discontinuation is frequent. Moreover, a lack of response is common in patient with high-grade glioma raising the need for further research into BRAFi+MEKi effects on tumors. We showed previously that BRAF V600E-mutated glioma cells positive for CD133 (Prominin-1), a marker of brain tumor stem cells, show decreased sensitivity to BRAFi, indicative of their role in promoting therapy resistance. BRAF V600E-mutated murine and patient-derived glioma cell lines (STN-10049, SU-aGBM5) were generated and together with established BRAF V600E-mutated cell lines (DBTRG, AM38) were analyzed for changes in gene expression in response to 48 hrs treatment with BRAFi dabrafenib and MEKi trametinib. Cells were analyzed by RNA-seq and gene enrichment analyses while cell culture supernatant was analyzed for cytokine production using an ELISA. Syngeneic, orthotopic BRAF V600E-mutated tumor allograft-bearing mice were treated with BRAFi+MEKi, with therapeutic antibodies against immune checkpoint molecules (anti-PD-L1 and anti-CTLA-4) and with combination of all four agents, and tumors were analyzed by mass cytometry and immunofluorescence for stem and T cell markers. BRAFi+MEKi treatment induced an interferon gamma (IFNg) response gene signature in BRAF V600E-mutated glioma cells and increased HLA gene expression. The frequency of tumor-infiltrating CD4+ CD8+ T cells in syngeneic BRAF V600E-mutated tumor allografts increased with BRAFi+MEKi treatment. Combining BRAFi+MEKi with anti-PD-L1 and anti-CTLA-4 treatment decreased CD133+ cells more effectively than either therapy alone, and resulted in a T cell-dependent survival benefit of mice with orthotopic BRAF V600E-mutated high-grade glioma. Combination of BRAFi+MEKi with immune checkpoint inhibition should be further explored as a viable option to prevent tumor rebound and therapy resistance in patients with BRAF V600E-mutated glioma.

EXTH-96. BIOPROCESSING OF SURGICAL PEDIATRIC BRAIN TUMOR SPECIMENS FOR GENOME-GUIDED PERSONALIZED DRUG TESTING

Novel treatment approaches for pediatric central nervous system (CNS) tumors are urgently needed. A lack of patient-derived tumor cells impedes progress towards developing such new therapies. We intended to overcome this challenge by establishing methods to create a biorepository of viable single cell suspensions of pediatric brain tumor surgical specimens. Quantitative and qualitative comparisons of tissue processing strategies were performed to preserve viability of heterogeneous tumor and immune cells. Novel drug targets were identified by analyzing pathways affected by RNA transcripts that are highly expressed (outliers) in a patients’ tumor; outliers for each patient were determined by RNA-seq data from individual patients’ tumors compared with a compendium of 12,747 pediatric and adult samples harmonized by the Treehouse Childhood Cancer Initiative at the UCSC Genomics Institute. The predicted anti-tumor efficacy of small molecule inhibitors of the outlier pathways was tested in cell viability assays against short-term cultured cells from matched patients. Successful tissue collection required obtaining informed consent, standard operating procedures, and sample recording using a Laboratory Inventory Management Software (LIMS). Since 2020 we have banked 67 pediatric CNS brain tumor specimens at Stanford. Amongst those, 51 cases yielded sufficient tissue for RNA-seq and cryoprotection. The most common tumor histology was low-grade glioma (LGG, 26 of 67), the majority of which were pilocytic astrocytoma (18 of 26). The second and third most common tumor types are embryonal tumors (6 medulloblastoma, 3 AT/RT) and ependymoma (4), respectively. We identified significant differences in cell viability with different preservation media. An outlier pathway previously not implicated in LGG was identified and sensitivity to a small molecule inhibitor of this outlier pathway was demonstrated. Taken together, we established feasibility for validating therapeutic vulnerabilities identified by a genome-guided approach in short-term cultures from surgical specimens. This works facilitates the rapid development of personalized CNS tumor treatment.

A 2-4 keV multilayer mirrored channel for the NIF Dante system

During inertial confinement fusion experiments at the National Ignition Facility (NIF), a capsule filled with deuterium and tritium (DT) gas, surrounded by a DT ice layer and a high-density carbon ablator, is driven to the temperature and densities required to initiate fusion. In the indirect method, 2 MJ of NIF laser light heats the inside of a gold hohlraum to a radiation temperature of 300 eV; thermal x rays from the hohlraum interior couple to the capsule and create a central hotspot at tens of millions degrees Kelvin and a density of 100-200 g/cm³. During the laser interaction with the gold wall, m-band x rays are produced at ∼2.5 keV; these can penetrate into the capsule and preheat the ablator and DT fuel. Preheat can impact instability growth rates in the ablation front and at the fuel-ablator interface. Monitoring the hohlraum x-ray spectrum throughout the implosion is, therefore, critical; for this purpose, a Multilayer Mirror (MLM) with flat response in the 2-4 keV range has been installed in the NIF 37° Dante calorimeter. Precision engineering and x-ray calibration of components mean the channel will report 2-4 keV spectral power with an uncertainty of ±8.7%.

Prediction of Intracranial Hypertension and Brain Tissue Hypoxia Utilizing High-Resolution Data from the BOOST-II Clinical Trial

The current approach to intracranial hypertension and brain tissue hypoxia is reactive, based on fixed thresholds. We used statistical machine learning on high-frequency intracranial pressure (ICP) and partial brain tissue oxygen tension (PbtO₂) data obtained from the BOOST-II trial with the goal of constructing robust quantitative models to predict ICP/PbtO₂ crises. We derived the following machine learning models: logistic regression (LR), elastic net, and random forest. We split the data set into 70–30% for training and testing and utilized a discrete-time survival analysis framework and 5-fold hyperparameter optimization strategy for all models. We compared model performances on discrimination between events and non-events of increased ICP or low PbtO₂ with the area under the receiver operating characteristic (AUROC) curve. We further analyzed clinical utility through a decision curve analysis (DCA). When considering discrimination, the number of features, and interpretability, we identified the RF model that combined the most recent ICP reading, episode number, and longitudinal trends over the preceding 30 min as the best performing for predicting ICP crisis events within the next 30 min (AUC 0.78). For PbtO₂, the LR model utilizing the most recent reading, episode number, and longitudinal trends over the preceding 30 min was the best performing (AUC, 0.84). The DCA showed clinical usefulness for wide risk of thresholds for both ICP and PbtO₂ predictions. Acceptable alerting thresholds could range from 20% to 80% depending on a patient-specific assessment of the benefit-risk ratio of a given intervention in response to the alert.

Hydrocephalus surveillance following CSF diversion: a modified Delphi study

OBJECTIVE

Long-term follow-up is often recommended for patients with hydrocephalus, but the frequency of clinical follow-up, timing and modality of imaging, and duration of surveillance have not been clearly defined. Here, the authors used the modified Delphi method to identify areas of consensus regarding the modality, frequency, and duration of hydrocephalus surveillance following surgical treatment.

METHODS

Pediatric neurosurgeons serving as institutional liaisons to the Hydrocephalus Clinical Research Network (HCRN), or its implementation/quality improvement arm (HCRNq), were invited to participate in this modified Delphi study. Thirty-seven consensus statements were generated and distributed via an anonymous electronic survey, with responses structured as a 4-point Likert scale (strongly agree, agree, disagree, strongly disagree). A subsequent, virtual meeting offered the opportunity for open discussion and modification of the statements in an effort to reach consensus (defined as ≥ 80% agreement or disagreement).

RESULTS

Nineteen pediatric neurosurgeons participated in the first round, after which 15 statements reached consensus. During the second round, 14 participants met virtually for review and discussion. Some statements were modified and 2 statements were combined, resulting in a total of 36 statements. At the conclusion of the session, consensus was achieved for 17 statements regarding the following: 1) the role of standardization; 2) preferred imaging modalities; 3) postoperative follow-up after shunt surgery (subdivided into immediate postoperative imaging, delayed postoperative imaging, routine clinical surveillance, and routine radiological surveillance); and 4) postoperative follow-up after an endoscopic third ventriculostomy. Consensus could not be achieved for 19 statements.

CONCLUSIONS

Using the modified Delphi method, 17 consensus statements were developed with respect to both clinical and radiological follow-up after a shunt or endoscopic third ventriculostomy. The frequency, modality, and duration of surveillance were addressed, highlighting areas in which no clear data exist to guide clinical practice. Although further studies are needed to evaluate the clinical utility and cost-effectiveness of hydrocephalus surveillance, the current study provides a framework to guide future efforts to develop standardized clinical protocols for the postoperative surveillance of patients with hydrocephalus. Ultimately, the standardization of hydrocephalus surveillance has the potential to improve patient care as well as optimize the use of healthcare resources.

Abstract CT001: Major tumor regressions in H3K27M-mutated diffuse midline glioma (DMG) following sequential intravenous (IV) and intracerebroventricular (ICV) delivery of GD2-CAR T cells

Background: H3K27M-mutated DMGs are universally lethal central nervous system tumors that express high levels of the disialoganglioside GD2. IV administered GD2-CAR T cells (GD2-CART) regress DMG in preclinical models, and locoregionally delivered CARs demonstrate enhanced activity in xenograft models of brain tumors.

Methods: NCT04196413 is a 3+3 Phase I dose escalation trial testing GD2-CART in patients with H3K27M DMG, with dose-limiting toxicities (DLT) considered independently for DIPG and spinal DMG (sDMG). Arm A tested escalating doses of IV GD2-CART (DL1: 1e6 GD2-CART/kg; DL2=3e6 GD2-CART/kg) following lymphodepletion (LD). After the DLT period, patients with clinical and/or radiographic benefit were eligible for subsequent ICV GD2-CART (10-30e6 GD2-CART) administered via Ommaya catheter without LD every 4-8 weeks for a maximum of 12 doses. We previously reported early results from 4 patients treated on DL1, which demonstrated clinical activity and manageable toxicity. Here we provide updated results for DL1 and DL2.

Results: Thirteen subjects were enrolled and 11 treated [n=4 DL1 (3 DIPG/1 sDMG); n=9 DL2 (7 DIPG/2 sDMG)]. Two subjects were removed prior to treatment due to rapid progression. No DLTs were observed on DL1. Three subjects experienced DLT on DL2 (2 DIPG/1 sDMG) due to grade 4 cytokine release syndrome (CRS), successfully managed with tocilizumab, anakinra, and corticosteroids. CRS occurred earlier on DL2 vs. DL1 (Day 3 vs 7). On both dose levels, all subjects exhibited transient symptoms related to on-tumor inflammation, termed Tumor Inflammation-Associated Neurotoxicity (TIAN), which was successfully managed with anakinra and, in some cases, CSF drainage and dexamethasone. No DLT due to TIAN has occurred.

Ten patients have had adequate follow-up to assess benefit. Nine experienced radiographic and/or clinical benefit after IV infusion, and they received subsequent ICV GD2-CART infusions (median= 4 ICV infusions/pt, range 1-6). ICV infusions were not associated with high-grade CRS, although some subjects developed transient fever, headache, meningismus, nausea, and/or vomiting, and several subjects developed TIAN. Four patients continue to receive ICV infusions on study and have experienced continued clinical and radiographic benefit at 11+, 9.5+, 8+ and 7+ months following enrollment. A 31-year-old with sDMG has experienced a near-complete (&gt;95%) reduction in tumor volume and a 17-year-old with DIPG experienced a near-complete (&gt;98%) reduction in volume of a pontine tumor.

Conclusions: IV treatment of DIPG and sDMG with GD2-CART is safe at a dose of 1e6/kg, but associated with unacceptable rates of high-grade CRS at 3e6/kg. ICV GD2-CART without LD, administered following a previous course of IV GD2-CART with LD, has been well tolerated and has mediated impressive sustained clinical benefit in some patients with DIPG/sDMG. Given these findings, we are launching a new arm to assess safety and activity and to define the recommended phase 2 dose for ICV delivery of GD2-CART without LD. Patients are eligible for up to 12 ICV infusions of GD2-CART administered every 4-6 weeks. Clinical benefit will be formally assessed using patient-reported outcomes. GD2-CART has the potential to transform therapy for patients with H3K27M+ DIPG/sDMG.

Citation Format: Robbie G. Majzner, Jasia Mahdi, Sneha Ramakrishna, Shabnum Patel, Harshini Chinnasamy, Kristen Yeom, Liora Schultz, Valentin Barsan, Rebecca Richards, Cynthia Campen, Agnes Reschke, Angus Martin Shaw Toland, Christina Baggott, Sharon Mavroukakis, Emily Egeler, Jennifer Moon, Ashley Jacobs, Karen Yamabe-Kwong, Lindsey Rasmussen, Esther Nie, Sean Green, Michael Kunicki, Michelle Fujimoto, Zach Ehlinger, Warren Reynolds, Snehit Prabhu, Katherine E. Warren, Tim Cornell, Sonia Partap, Paul Fisher, Gerald Grant, Hannes Vogel, Bita Sahaf, Kara Davis, Steven Feldman, Michelle Monje, Crystal L. Mackall. Major tumor regressions in H3K27M-mutated diffuse midline glioma (DMG) following sequential intravenous (IV) and intracerebroventricular (ICV) delivery of GD2-CAR T cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT001.

DIPG-15. Major tumor regressions in H3K27M-mutated diffuse midline glioma (DMG) following sequential intravenous (IV) and intracerebroventricular (ICV) delivery of GD2-CAR T-cells

BACKGROUND: H3K27M-mutated DMGs express high levels of the disialoganglioside GD2 and GD2-CAR T-cells (GD2-CART) regress DMG in preclinical models. METHODS: NCT04196413 is a 3 + 3 Phase I dose escalation trial testing GD2-CART in patients with biopsy-proved H3K27M DMG, with dose-limiting toxicities (DLT) considered independently for DIPG and spinal DMG (sDMG). Arm A tested escalating doses of IV GD2-CART (DL1=1e6 GD2-CART/kg; DL2=3e6 GD2-CART/kg) following lymphodepletion (LD). After the DLT period, patients with clinical and/or radiographic benefit were eligible for subsequent ICV GD2-CART infusions (10-30e6 GD2-CART) administered via Ommaya without LD. RESULTS: Twelve subjects were treated after standard radiotherapy, 7 of whom began treatment at the time of progression [n=4 DL1 (3 DIPG/1 sDMG); n=8 DL2 (6 DIPG/2 sDMG)]. No DLTs were observed on DL1. Three subjects experienced DLT on DL2 (2 DIPG/1 sDMG) due to grade-4 cytokine release syndrome (CRS). On both dose levels, all subjects exhibited transient symptoms related to on-tumor inflammation, termed Tumor Inflammation-Associated Neurotoxicity (TIAN); no DLT due to TIAN has occurred. Ten subjects experienced radiographic and/or clinical benefit after IV infusion and received subsequent ICV infusions (median=4 ICV infusions/pt, range=1-7). ICV infusions were not associated with high-grade CRS. Four patients continue to receive ICV infusions on study and have experienced continued clinical and radiographic benefit, currently 7-11 months following enrollment. Two patients (one sDMG, one DIPG) have experienced near-complete (>95%) tumor volume reduction. CONCLUSIONS: IV treatment of DIPG and sDMG with GD2-CART is safe at a dose of 1e6/kg, but associated with frequent high-grade CRS at 3e6/kg. ICV GD2-CART has been well tolerated and has mediated impressive sustained clinical benefit in some patients with DIPG/sDMG. Given these findings, we are launching a new arm to assess safety and activity and to define the recommended phase 2 dose for ICV delivery of GD2-CART without LD.

IMG-02. Improved prediction of postoperative paediatric cerebellar mutism syndrome using an artificial neural network

BACKGROUND: Postoperative paediatric cerebellar mutism syndrome (pCMS) is a common but severe complication which may arise following the resection of posterior fossa tumours in children. Two previous studies have aimed to preoperatively predict pCMS, with varying results. In this work, we examine the generalisation of these models and determine if pCMS can be predicted more accurately using an artificial neural network (ANN). METHODS: An overview of reviews was performed to identify risk factors for pCMS, and a retrospective dataset collected as per these defined risk factors from children undergoing resection of primary posterior fossa tumours. The ANN was trained on this dataset and its performance evaluated in comparison to logistic regression and other predictive indices via analysis of receiver operator characteristic curves. Area under the curve (AUC) and accuracy were calculated and compared using a Wilcoxon signed rank test, with p&lt;0.05 considered statistically significant. RESULTS: 204 children were included, of whom 80 developed pCMS. The performance of the ANN (AUC 0.949; accuracy 90.9%) exceeded that of logistic regression (p&lt;0.05) and both external models (p&lt;0.001). CONCLUSION: Using an ANN, we show improved prediction of pCMS in comparison to previous models and conventional methods.

RARE-24. The use of novelin vitro models to study adamantinomatous craniopharyngioma disease biology and drug response

BACKGROUND: Challenges around the design and investigation of cell culture models of adamantinomatous craniopharyngioma (ACP) have arisen from the cellular heterogeneity of these tumors, with populations that harbor disparate requirements in culture. Novel approaches to in vitro modeling of ACP are needed. METHODS: Intraoperatively collected tumor specimens were mechanically digested and plated under conditions tailored to the cell population of interest. ACP tumor-derived fibroblasts and epithelial cells were isolated using serum-containing and keratinocyte-specific media respectively. ACP-derived epithelial cells were immortalized via SV40 virus transfection and puromycin treatment for stable cell-line generation. Cell line validation included immunofluorescence with markers appropriate for the cell population of interest. RNA sequencing of cell lines was compared to ACP transcriptome reference data. Cell typing was conducted using short tandem repeat sequencing. RESULTS: ACP fibroblasts and ACP epithelial cells maintained spindle-like and cobblestone morphologies respectively, even after 4 passages. Immunofluorescence staining confirmed high levels of Vimentin expression in ACP-derived fibroblasts, and panCK and B-catenin in ACP-derived epithelial cells. Point mutation in exon 3 of the CTNNB1 gene was identified in ACP-derived epithelial cells. CONCLUSION: Initial limits related to cell line development in ACP may be addressed through the isolation and culture-specific ACP cell populations. This experience demonstrates the maintenance of validated markers of the cell populations of interest ex vivo. While preliminary, such cell lines offer promise as tools for the identification and study of potential therapeutic vulnerabilities in ACP.

Rationale and Methods for Updated Guidelines for the Management of Penetrating Traumatic Brain Injury

Penetrating traumatic brain injury (pTBI) affects civilian and military populations resulting in significant morbidity, mortality, and healthcare costs. No up-to-date and evidence-based guidelines exist to assist modern medical and surgical management of these complex injuries. A preliminary literature search revealed a need for updated guidelines, supported by the Brain Trauma Foundation. Methodologists experienced in TBI guidelines were recruited to support project development alongside two cochairs and a diverse steering committee. An expert multi-disciplinary workgroup was established and vetted to inform key clinical questions, to perform an evidence review and the development of recommendations relevant to pTBI. The methodological approach for the project was finalized. The development of up-to-date evidence- and consensus-based clinical care guidelines and algorithms for pTBI will provide critical guidance to care providers in the pre-hospital and emergent, medical, and surgical settings.

Age-dependent white matter disruptions after military traumatic brain injury: Multivariate analysis results from ENIGMA brain injury

Mild Traumatic brain injury (mTBI) is a signature wound in military personnel, and repetitive mTBI has been linked to age-related neurogenerative disorders that affect white matter (WM) in the brain. However, findings of injury to specific WM tracts have been variable and inconsistent. This may be due to the heterogeneity of mechanisms, etiology, and comorbid disorders related to mTBI. Non-negative matrix factorization (NMF) is a data-driven approach that detects covarying patterns (components) within high-dimensional data. We applied NMF to diffusion imaging data from military Veterans with and without a self-reported TBI history. NMF identified 12 independent components derived from fractional anisotropy (FA) in a large dataset (n = 1,475) gathered through the ENIGMA (Enhancing Neuroimaging Genetics through Meta-Analysis) Military Brain Injury working group. Regressions were used to examine TBI- and mTBI-related associations in NMF-derived components while adjusting for age, sex, post-traumatic stress disorder, depression, and data acquisition site/scanner. We found significantly stronger age-dependent effects of lower FA in Veterans with TBI than Veterans without in four components (q < 0.05), which are spatially unconstrained by traditionally defined WM tracts. One component, occupying the most peripheral location, exhibited significantly stronger age-dependent differences in Veterans with mTBI. We found NMF to be powerful and effective in detecting covarying patterns of FA associated with mTBI by applying standard parametric regression modeling. Our results highlight patterns of WM alteration that are differentially affected by TBI and mTBI in younger compared to older military Veterans.

The Presence of the Temporal Horn Exacerbates the Vulnerability of Hippocampus During Head Impacts

Hippocampal injury is common in traumatic brain injury (TBI) patients, but the underlying pathogenesis remains elusive. In this study, we hypothesize that the presence of the adjacent fluid-containing temporal horn exacerbates the biomechanical vulnerability of the hippocampus. Two finite element models of the human head were used to investigate this hypothesis, one with and one without the temporal horn, and both including a detailed hippocampal subfield delineation. A fluid-structure interaction coupling approach was used to simulate the brain-ventricle interface, in which the intraventricular cerebrospinal fluid was represented by an arbitrary Lagrangian-Eulerian multi-material formation to account for its fluid behavior. By comparing the response of these two models under identical loadings, the model that included the temporal horn predicted increased magnitudes of strain and strain rate in the hippocampus with respect to its counterpart without the temporal horn. This specifically affected cornu ammonis (CA) 1 (CA1), CA2/3, hippocampal tail, subiculum, and the adjacent amygdala and ventral diencephalon. These computational results suggest that the presence of the temporal horn exacerbate the vulnerability of the hippocampus, highlighting the mechanobiological dependency of the hippocampus on the temporal horn.

GD2-CAR T cell therapy for H3K27M-mutated diffuse midline gliomas

Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMGs) are universally lethal paediatric tumours of the central nervous system¹. We have previously shown that the disialoganglioside GD2 is highly expressed on H3K27M-mutated glioma cells and have demonstrated promising preclinical efficacy of GD2-directed chimeric antigen receptor (CAR) T cells², providing the rationale for a first-in-human phase I clinical trial (NCT04196413). Because CAR T cell-induced brainstem inflammation can result in obstructive hydrocephalus, increased intracranial pressure and dangerous tissue shifts, neurocritical care precautions were incorporated. Here we present the clinical experience from the first four patients with H3K27M-mutated DIPG or spinal cord DMG treated with GD2-CAR T cells at dose level 1 (1 × 10⁶ GD2-CAR T cells per kg administered intravenously). Patients who exhibited clinical benefit were eligible for subsequent GD2-CAR T cell infusions administered intracerebroventricularly³. Toxicity was largely related to the location of the tumour and was reversible with intensive supportive care. On-target, off-tumour toxicity was not observed. Three of four patients exhibited clinical and radiographic improvement. Pro-inflammatory cytokine levels were increased in the plasma and cerebrospinal fluid. Transcriptomic analyses of 65,598 single cells from CAR T cell products and cerebrospinal fluid elucidate heterogeneity in response between participants and administration routes. These early results underscore the promise of this therapeutic approach for patients with H3K27M-mutated DIPG or spinal cord DMG.

Improved prediction of postoperative paediatric cerebellar mutism syndrome using an artificial neural network

Background

Postoperative paediatric cerebellar mutism syndrome (pCMS) is a common but severe complication which may arise following the resection of posterior fossa tumours in children. Two previous studies have aimed to preoperatively predict pCMS, with varying results. In this work, we examine the generalisation of these models and determine if pCMS can be predicted more accurately using an artificial neural network (ANN).

Methods

An overview of reviews was performed to identify risk factors for pCMS, and a retrospective dataset collected as per these defined risk factors from children undergoing resection of primary posterior fossa tumours. The ANN was trained on this dataset and its performance evaluated in comparison to logistic regression and other predictive indices via analysis of receiver operator characteristic curves. Area under the curve (AUC) and accuracy were calculated and compared using a Wilcoxon signed rank test, with p&lt;0.05 considered statistically significant.

Results

204 children were included, of whom 80 developed pCMS. The performance of the ANN (AUC 0.949; accuracy 90.9%) exceeded that of logistic regression (p&lt;0.05) and both external models (p&lt;0.001).

Conclusion

Using an ANN, we show improved prediction of pCMS in comparison to previous models and conventional methods.

The current landscape of immunotherapy for pediatric brain tumors

Pediatric central nervous system tumors are the most common solid malignancies in childhood, and aggressive therapy often leads to long-term sequelae in survivors, making these tumors challenging to treat. Immunotherapy has revolutionized prospects for many cancer types in adults, but the intrinsic complexity of treating pediatric patients and the scarcity of clinical studies of children to inform effective approaches have hampered the development of effective immunotherapies in pediatric settings. Here, we review recent advances and ongoing challenges in pediatric brain cancer immunotherapy, as well as considerations for efficient clinical translation of efficacious immunotherapies into pediatric settings.

An Atlas of the Quantitative Protein Expression of Anti-Epileptic-Drug Transporters, Metabolizing Enzymes and Tight Junctions at the Blood-Brain Barrier in Epileptic Patients

The purpose of the present study was to quantitatively elucidate the levels of protein expression of anti-epileptic-drug (AED) transporters, metabolizing enzymes and tight junction molecules at the blood–brain barrier (BBB) in the focal site of epilepsy patients using accurate SWATH (sequential window acquisition of all theoretical fragment ion spectra) proteomics. Brain capillaries were isolated from focal sites in six epilepsy patients and five normal brains; tryptic digests were produced and subjected to SWATH analysis. MDR1 and BCRP were significantly downregulated in the epilepsy group compared to the normal group. Out of 16 AED-metabolizing enzymes detected, the protein expression levels of GSTP1, GSTO1, CYP2E1, ALDH1A1, ALDH6A1, ALDH7A1, ALDH9A1 and ADH5 were significantly 2.13-, 6.23-, 2.16-, 2.80-, 1.73-, 1.67-, 2.47- and 2.23-fold greater in the brain capillaries of epileptic patients than those of normal brains, respectively. The protein expression levels of Claudin-5, ZO-1, Catenin alpha-1, beta-1 and delta-1 were significantly lower, 1.97-, 2.51-, 2.44-, 1.90- and 1.63-fold, in the brain capillaries of epileptic patients compared to those of normal brains, respectively. Consistent with these observations, leakage of blood proteins was also observed. These results provide for a better understanding of the therapeutic effect of AEDs and molecular mechanisms of AED resistance in epileptic patients.

EXTH-42. COMBINATION OF MAPK PATHWAY INHIBITORS AND IMMUNE CHECKPOINT BLOCKADE IN BRAF-MUTANT HIGH-GRADE GLIOMA

BACKGROUND

Despite successes, clinical MAPK pathway inhibitors show limited anti-tumor activity in the majority of patients with BRAF-mutant high-grade glioma. Because of the presence of higher fraction of CD8+ tumor-infiltrating T cells in MAPK pathway-altered glioma, we explored the possibility that combined BRAF and MEK inhibition with immune checkpoint blockade enhances anti-tumor response.

METHODS

We engineered mice to carry BRAF V600E expression and CDKN2A deletion in various hemispheric areas. We treated syngeneic tumor-bearing mice with dabrafenib, trametinib, anti-PD-L1 and anti-CTLA-4 antibodies, and analyzed the tumor immune infiltrate by high-dimensional single-cell mass cytometry (CyTOF). RNA sequencing and Gene Set Enrichment Analysis were conducted using patient-derived BRAF-mutant glioma lines upon the inhibitor treatment.

RESULTS

The transcriptome analysis demonstrated that antigen processing and presentation feature is strongly enriched upon dual MAPK pathway inhibition. Consistent with these molecular changes, dabrafenib and trametinib treatment led to dynamic changes in tumor-infiltrating immune cells, including CD8+ and CD4+ T cells. In line with this, combination of MAPK pathway and immune checkpoint inhibitors elicit a significant survival benefit over MAPK pathway inhibition alone in mice with orthotopic BRAF-mutant glioma.

CONCLUSIONS

Clinically relevant molecular targeted therapy by dabrafenib and trametinib and immune checkpoint blockade synergize in pre-clinical models.

Optimization of a Thermal Flow Meter for Failure Management of the Shunt in Pediatric Hydrocephalus Patients. Annu Int Conf IEEE Eng Med Biol Soc 2021;2021:1551-1556. [PMID: 34891580 DOI: 10.1109/embc46164.2021.9630302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Hydrocephalus patients suffer from an abnormal buildup of cerebrospinal fluid (CSF) in their ventricles, and there is currently no known way to cure hydrocephalus. The most prevalent treatment for managing hydrocephalus is to implant a ventriculoperitoneal shunt, which diverts excess CSF out of the brain. However, shunts are prone to failure, resulting in vague symptoms. Our patient survey results found that the lack of specificity of symptoms complicates the management of hydrocephalus in the pediatric population. The consequences include persistent mental burden on caretakers and a significant amount of unnecessary utilization of emergency healthcare resources due to the false-positive judgement of shunt failure. In order to reliably monitor shunt failures for hydrocephalus patients and their caretakers, we propose an optimized design of the thermal flow meter for precise measurements of the CSF flow rate in the shunt. The design is an implantable device which slides onto the shunt and utilizes sinusoidal heating and temperature measurements to improve the signal-to-noise ratio of flow-rate measurements by orders of magnitude.Clinical Relevance- An implantable flow meter would be transformative to allow hydrocephalus patients to monitor their shunt function at home, resulting in reduced hospital visits, reduced exposure to radiation typically required to rule out shunt failure, and reduced caretaker anxiety.

Spatiotemporal changes in along-tract profilometry of cerebellar peduncles in cerebellar mutism syndrome

Aims

Cerebellar mutism syndrome occurs in 25% of children following resection of posterior fossa tumours. Characterised by mutism, emotional lability and cerebellar motor signs, the syndrome is usually reversible over weeks to months. Its pathophysiology remains unclear, but evidence from diffusion MRI studies has implicated damage to the superior cerebellar peduncles in the development of this condition. The objective of this study was to describe the application of automated tractography of the cerebellar peduncles to provide a high-resolution spatiotemporal profile of diffusion MRI changes in cerebellar mutism syndrome.

Method

A retrospective case-control study was performed at Lucille Packard Children’s Hospital, Stanford University. Thirty children with midline medulloblastoma (mean age ± standard deviation 8.8 ± 3.8 years) underwent volumetric T1-weighted and diffusion MRI at four timepoints over one year. Forty-nine healthy children (9.0 ± 4.2 years), scanned at a single timepoint, were included as age- and sex-matched controls. Cerebellar mutism syndrome status was determined by contemporaneous casenote review. Automated Fibre Quantification was used to segment each subject’s cerebellar peduncles (Figure 1), and fractional anisotropy was computed at 30 nodes along each tract. A non-parametric permutation-based method was used to generate a critical cluster size and p-value for by-node ANOVA group comparisons. Z-scores for patients’ fractional anisotropy at each node were calculated based on values from controls’ corresponding nodes; these were analysed using mixed ANOVA with post-hoc false discovery rate-corrected pairwise t-tests.

Results

13 patients developed cerebellar mutism syndrome. Automated fibre segmentation successfully identified the cerebellar peduncles in the majority of participants, but was more robust at follow-up timepoints (78.7% vs. 44.7% pre-operatively). Fractional anisotropy was significantly lower in the distal regions of the left superior cerebellar peduncle pre-operatively (p=0.0137) in patients compared to controls, although patients could not be distinguished pre-operatively with respect to cerebellar mutism syndrome status (Figure 2). Post-operative reductions in fractional anisotropy in children with cerebellar mutism syndrome were highly specific to the distal left superior cerebellar peduncle, and were most pronounced at follow-up timepoints (p=0.006; Figure 3). There were no significant differences in other cerebellar peduncles, either in along-tract fractional anisotropy or Z-scores, with respect to cerebellar mutism syndrome status.

Conclusion

A novel application of an automated tool to extract diffusion MRI data along the length of the cerebellar peduncles is described in a longitudinal retrospective cohort of paediatric medulloblastoma. Changes in fractional anisotropy in the cerebellar peduncles following tumour resection are described in a heretofore unprecedented level of spatiotemporal detail. In particular, children with post-operative cerebellar mutism syndrome show changes in the distal regions of the left superior cerebellar peduncle, and these changes persist up to a year post-operatively. These findings will have direct clinical implications for neurosurgeons performing resection of midline paediatric posterior fossa tumours.

Toward a Comprehensive Delineation of White Matter Tract-Related Deformation

Finite element (FE) models of the human head are valuable instruments to explore the mechanobiological pathway from external loading, localized brain response, and resultant injury risks. The injury predictability of these models depends on the use of effective criteria as injury predictors. The FE-derived normal deformation along white matter (WM) fiber tracts (i.e., tract-oriented strain) recently has been suggested as an appropriate predictor for axonal injury. However, the tract-oriented strain only represents a partial depiction of the WM fiber tract deformation. A comprehensive delineation of tract-related deformation may improve the injury predictability of the FE head model by delivering new tract-related criteria as injury predictors. Thus, the present study performed a theoretical strain analysis to comprehensively characterize the WM fiber tract deformation by relating the strain tensor of the WM element to its embedded fiber tract. Three new tract-related strains with exact analytical solutions were proposed, measuring the normal deformation perpendicular to the fiber tracts (i.e., tract-perpendicular strain), and shear deformation along and perpendicular to the fiber tracts (i.e., axial-shear strain and lateral-shear strain, respectively). The injury predictability of these three newly proposed strain peaks along with the previously used tract-oriented strain peak and maximum principal strain (MPS) were evaluated by simulating 151 impacts with known outcome (concussion or non-concussion). The results preliminarily showed that four tract-related strain peaks exhibited superior performance than MPS in discriminating concussion and non-concussion cases. This study presents a comprehensive quantification of WM tract-related deformation and advocates the use of orientation-dependent strains as criteria for injury prediction, which may ultimately contribute to an advanced mechanobiological understanding and enhanced computational predictability of brain injury.

Factors Associated with Early Neonatal and First-Year Mortality in Infants with Myelomeningocele in California from 2006 to 2011

OBJECTIVE

The aim of this study is to examine factors associated with early neonatal (death within first 7 days of birth) and infant (death during the first year of life) mortality among infants born with myelomeningocele.

STUDY DESIGN

We examined linked data from the California Perinatal Quality Care Collaborative, vital records, and hospital discharge records for infants born with myelomeningocele from 2006 to 2011. Survival probability was calculated using Kaplan-Meier Product Limit method and 95% confidence intervals (CI) using Greenwood's method; Cox proportional hazard models were used to estimate unadjusted and adjusted hazard ratios (HR) and 95% CI.

RESULTS

Early neonatal and first-year survival probabilities among infants born with myelomeningocele were 96.0% (95% CI: 94.1-97.3%) and 94.5% (95% CI: 92.4-96.1%), respectively. Low birthweight and having multiple co-occurring birth defects were associated with increased HRs ranging between 5 and 20, while having congenital hydrocephalus and receiving hospital transfer from the birth hospital to another hospital for myelomeningocele surgery were associated with HRs indicating a protective association with early neonatal and infant mortality.

CONCLUSION

Maternal race/ethnicity and social disadvantage did not predict early neonatal and infant mortality among infants with myelomeningocele; presence of congenital hydrocephalus and the role of hospital transfer for myelomeningocele repair should be further examined.

KEY POINTS

· Mortality in myelomeningocele is a concern. · Social disadvantage was not associated with death. · Hospital-based factors should be further examined.

Neuroradiologic Evaluation of MRI in High-Contact Sports

Background and Purpose: Athletes participating in high-contact sports experience repeated head trauma. Anatomical findings, such as a cavum septum pellucidum, prominent CSF spaces, and hippocampal volume reductions, have been observed in cases of mild traumatic brain injury. The extent to which these neuroanatomical findings are associated with high-contact sports is unknown. The purpose of this study was to determine whether there are subtle neuroanatomic differences between athletes participating in high-contact sports compared to low-contact athletic controls.

Materials and Methods: We performed longitudinal structural brain MRI scans in 63 football (high-contact) and 34 volleyball (low-contact control) male collegiate athletes with up to 4 years of follow-up, evaluating a total of 315 MRI scans. Board-certified neuroradiologists performed semi-quantitative visual analysis of neuroanatomic findings, including: cavum septum pellucidum type and size, extent of perivascular spaces, prominence of CSF spaces, white matter hyperintensities, arterial spin labeling perfusion asymmetries, fractional anisotropy holes, and hippocampal size.

Results: At baseline, cavum septum pellucidum length was greater in football compared to volleyball controls (p = 0.02). All other comparisons were statistically equivalent after multiple comparison correction. Within football at baseline, the following trends that did not survive multiple comparison correction were observed: more years of prior football exposure exhibited a trend toward more perivascular spaces (p = 0.03 uncorrected), and lower baseline Standardized Concussion Assessment Tool scores toward more perivascular spaces (p = 0.02 uncorrected) and a smaller right hippocampal size (p = 0.02 uncorrected).

Conclusion: Head impacts in high-contact sport (football) athletes may be associated with increased cavum septum pellucidum length compared to low-contact sport (volleyball) athletic controls. Other investigated neuroradiology metrics were generally equivalent between sports.

Abstract CT031: GD2 CAR T cells mediate clinical activity and manageable toxicity in children and young adults with DIPG and H3K27M-mutated diffuse midline gliomas

Background: Diffuse intrinsic pontine glioma (DIPG) and other H3K27M-mutated diffuse midline gliomas (DMGs) are universally lethal central nervous system tumors. We previously discovered that the disialoganglioside GD2 is highly and homogenously expressed on H3K27M+ gliomas and demonstrated that GD2 CAR T cells are effective in preclinical models (Mount/Majzner et al., Nat Med, 2018).

Methods: Four subjects (3 DIPG, 1 spinal cord DMG; 4-25 yr; 1M/3F) were enrolled at DL1. Three subjects with H3K27M+ DIPG received 1e6 autologous GD2 CAR T cells/kg intravenously (IV) on study. One patient, a 25 y/o with spinal cord DMG, developed rapidly progressive disease after enrollment, resulting in complete paraparesis that led to removal from the study prior to cell infusion; she was treated on a single patient eIND with the same treatment regimen as DL1. We utilized a retroviral vector expressing a 14g2a.4-1BB.z CAR construct and an inducible iCasp9 safety switch. Manufacturing was performed in the Miltenyi Prodigy on CD4/CD8 enriched apheresis product. CAR T cells were cultured in the presence of dasatinib to improve T cell fitness (Weber et al., Science, 2021). An Ommaya reservoir was placed in all patients for monitoring of intracranial pressure (ICP).

Results: We generated GD2 CAR T cell products meeting release criteria for all four patients. All subjects received lymphodepletion with cyclophosphamide and fludarabine and remained inpatient for 14+ days after infusion. All patients developed cytokine release syndrome (Grade 1-3) manifested by fever, tachycardia and hypotension, beginning 6-7 days after infusion. Due to concern for tumoral edema and increased ICP, patients were managed with conservative fluid resuscitation, and early intervention with tocilizumab and anakinra +/- corticosteroids. Other toxicities included ICANS (Grade 1-2) and neurotoxicity mediated by inflammation in sites of disease which we have termed Tumor Inflammation-Associated Neurotoxicity (TIAN). TIAN most often manifested as worsening of existing deficits, but one patient developed symptoms of increased ICP which quickly resolved upon removal of CSF via the Ommaya. No evidence of on-target, off-tumor toxicity was observed in any patients. No dose-limiting toxicities occurred.CAR T cells trafficked to the CNS and were detected in both the CSF and peripheral blood. Inflammatory cytokines including IL-6 were elevated in the CSF and blood. 3/4 patients exhibited marked improvement or resolution of neurological deficits and some radiographic improvement. The patient treated on a single patient eIND exhibited a &gt;90% reduction in her spinal cord DMG tumor volume at two months post-infusion. Durability of the therapeutic benefit remains to be determined.

Conclusions: This is the first report of GD2 CAR T cell therapy for DIPG and spinal cord DMG. Toxicities are similar to other CAR T cells with additional, manageable complications due to inflammation at CNS sites of tumor. Treatment at DL1 demonstrated a tolerable safety profile and clear signs of T cell expansion and activity including clinical responses. This approach has the potential to transform therapy for patients with H3K27M+ DIPG/DMG. Further correlative studies, including single-cell RNAseq, longer-term outcomes and results from patients on subsequent dose levels will also be presented.

Citation Format: Robbie G. Majzner, Sneha Ramakrishna, Aaron Mochizuki, Shabnum Patel, Harshini Chinnasamy, Kristen Yeom, Liora Schultz, Rebecca Richards, Cynthia Campen, Agnes Reschke, Jasia Mahdi, Angus Martin Shaw Toland, Christina Baggott, Sharon Mavroukakis, Emily Egeler, Jennifer Moon, Kayla Landrum, Courtney Erickson, Lindsey Rasmussen, Valentin Barsan, John S. Tamaresis, Anne Cunniffe Marcy, Michael Kunicki, Michelle Fujimoto, Zach Ehlinger, Sreevidya Kurra, Timothy Cornell, Sonia Partap, Paul Fisher, Gerald Grant, Hannes Vogel, Bita Sahaf, Kara Davis, Steven Feldman, Crystal L. Mackall, Michelle Monje. GD2 CAR T cells mediate clinical activity and manageable toxicity in children and young adults with DIPG and H3K27M-mutated diffuse midline gliomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT031.

Endoscopic Endonasal Surgery for Resection of Giant Craniopharyngioma in a Toddler-Multimodal Presurgical Planning, Surgical Technique, and Management of Complications: 2-Dimensional Operative Video

A 2-yr-old patient with a giant craniopharyngioma presented with seizures and panhypopituitarism. The lesion was initially approached at an outside institution with a transfrontal cyst fenestration, but progressive growth occurred later. Multiple management options were considered; we recommended an endoscopic endonasal approach with the goal of maximal safe resection. Virtual reality simulation and 3-dimensional printing were employed to evaluate whether the absence of pneumatization of the sinuses and the overall size of the nasal cavity could preclude effective surgical access. Our lab results suggested the binostril approach was feasible. A wide surgical exposure was performed from planum sphenoidale to clivus and from orbit to orbit. After removing the large calcified tumor portion, we found an accurate plane of dissection between tumor capsule, hypothalami, and visual pathways. By the end of resection, arterial bleeding was encountered secondary to an avulsion of the posterior communicating artery from the posterior cerebral artery. An angled aneurysm clip was placed with a single-shaft applier to secure the site of injury without narrowing the parent artery. Immediate and delayed magnetic resonance imaging and computed tomography angiography studies showed gross total resection, no stroke, and no pseudoaneurysm formation. On postoperative day 9, patient developed neurological decline and pneumocephalus secondary to necrotic nasoseptal flap. Two endonasal repairs with a lateral nasal wall flap were attempted with no success. A temporoparietal fascia flap was then harvested and transposed from the temporal to the pterygopalatine fossa to successfully repair the skull base defect. The patient has made an extraordinary recovery with no neurological sequalae. The patient's parents provided consent for the procedure and use of intraoperative photos and videos for academic purposes. Institutional Review Board approval was not required.

OMIC-11. SINGLE CELL RNA SEQUENCING FROM THE CSF OF SUBJECTS WITH H3K27M+ DIPG/DMG TREATED WITH GD2 CAR T-CELLULAR THERAPY

Introduction

We are conducting a Phase I clinical trial utilizing chimeric antigen receptor (CAR) T-cells targeting GD2 (NCT04196413) for H3K27M-mutant diffuse intrinsic pontine glioma (DIPG) and spinal cord diffuse midline glioma (DMG). Cerebrospinal fluid (CSF) is collected for correlative studies at the time of routine intracranial pressure monitoring via Ommaya catheter. Here we present single cell RNA-sequencing results from the first 3 subjects.

Methods

Single cell RNA-sequencing was performed utilizing 10X Genomics on cells isolated from CSF at various time points before and after CAR T-cell administration and on the CAR T-cell product. Output was aligned with Cell Ranger and analyzed in R.

Results

As detailed in the Majzner et al. abstract presented at this meeting, three of four subjects treated at dose-level one exhibited clear radiographic and/or clinical benefit. We have to date completed single cell RNA-sequencing for three of these four subjects (two with benefit, one without). After filtering out low-quality signals and doublets, 89,604 cells across 3 subjects were analyzed. Of these, 4,122 cells represent cells isolated from CSF and 85,482 cells represent CAR T-cell product. Two subjects who demonstrated clear clinical and radiographic improvement exhibited fewer S100A8⁺S100A9⁺ myeloid suppressor-cells and CD25⁺FOXP3⁺ regulatory T-cells in the CSF pre-infusion compared to the subject who did not derive a therapeutic response. In one subject with DIPG who demonstrated improvement, polyclonal CAR T-cells detectable in CSF at Day +14 demonstrated enrichment of CD8A, GZMA, GNLY and PDCD1 compared to the pre-infusion CAR T-cells by trajectory analysis, suggesting differentiation toward a cytotoxic phenotype; the same subject exhibited increasing numbers of S100A8⁺S100A9⁺ myeloid cells and CX3CR1⁺P2RY12⁺ microglia over time. Further analyses will be presented as data become available.

Conclusions

The presence of immunosuppressive myeloid populations, detectable in CSF, may correlate to clinical response in CAR T cell therapy for DIPG/DMG.

EPCT-14. GD2 CAR T-CELLS MEDIATE CLINICAL ACTIVITY AND MANAGEABLE TOXICITY IN CHILDREN AND YOUNG ADULTS WITH H3K27M-MUTATED DIPG AND SPINAL CORD DMG

Background

We previously discovered high expression of the disialoganglioside GD2 on H3K27M+ gliomas and demonstrated preclinical efficacy of intravenous (IV) GD2-targeted chimeric antigen receptor (CAR) T-cells in preclinical models of H3K27M-mutated diffuse intrinsic pontine glioma (DIPG) and diffuse midline gliomas (DMGs). We are now conducting a Phase I clinical trial (NCT04196413) of autologous GD2-targeting CAR T-cells for H3K27M+ DIPG and spinal cord DMG. Here we present the results of subjects treated at dose level 1 (DL1; 1 million GD2-CAR T-cells/kg IV).

Methods

Four patients (3 DIPG, 1 spinal DMG; ages 4–25; 1M/3F) were enrolled at DL1. Three subjects with H3K27M+ DIPG received 1e6 GD2-CAR T-cells/kg IV on study. One patient with spinal DMG enrolled but became ineligible after manufacturing and was treated on an eIND at DL1. An Ommaya reservoir was placed in all subjects for therapeutic monitoring of intracranial pressure. Subjects underwent lymphodepletion with fludarabine/cyclophosphamide and remained inpatient for at least two weeks post-infusion.

Results

All subjects developed cytokine release syndrome (Grade 1–3) manifested by fever, tachycardia and hypotension. Other toxicities included ICANS (Grade 1–2) and neurological symptoms/signs mediated by intratumoral inflammation which we have termed Tumor Inflammation-Associated Neurotoxicity (TIAN). No evidence of on-target, off-tumor toxicity was observed in any patients. No dose-limiting toxicities occurred. CAR T cells trafficked to the CNS and were detected in CSF and blood. 3/4 patients exhibited marked improvement or resolution of neurological deficits and radiographic improvement. The patient treated on an eIND exhibited &gt;90% reduction in spinal DMG volume but progressed by month 3. Re-treatment of this subject via intracerebroventricular administration resulted in a second reduction in spinal DMG volume by ~80%.

Conclusions

GD2-CAR T-cells at DL1 demonstrate a tolerable safety profile in patients with H3K27M+ DIPG/DMG with clear signs of T-cell expansion and activity including clinical responses.

BIOL-05. MAPK PATHWAY INHIBITION SENSITIZES TO IMMUNOTHERAPY IN BRAF-MUTANT GLIOMAS

Background

BRAF alterations frequently occur in pediatric low-grade gliomas. Previously, we showed that dabrafenib and trametinib (D+T) that target MAPK pathway can mediate the antitumor effect in a preclinical model of BRAF-mutant glioma (PMC5342782). Here, we further investigate the effect of MAPK pathway inhibitors on cancer cells and tumor-infiltrating immune cells to maximize the therapeutic efficacy in malignant gliomas.

Methods

Drug concentrations in tumor, brain and plasma were assessed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). RNA sequencing and Gene Set Enrichment Analysis were performed using patient-derived BRAF-mutant glioma lines upon D+T treatment. Molecular profiles of drug-resistant clones were assessed for understanding of glioma heterogeneity and exploring new therapeutic targets. Results. BRAF-mutant stem-like glioma cells were particularly resistant to BRAF or MAPK inhibitor, along with aggressive phenotype in mice. LC-MS/MS showed effective D+T drug delivery in tumor regions. The transcriptome analysis demonstrated that D+T upregulate HLA molecules and downregulate immunosuppressive factors in patient-derived BRAF-mutant glioma lines. Consistent with these molecular changes, D+T led to changes in the proportions of tumor-infiltrating immune cells, including CD8+ cytotoxic T lymphocytes and FOXP3+ regulatory T cells. Furthermore, the therapeutic effect of D+T was further enhanced in combination with immune checkpoint inhibition.

Conclusions

The present study highlights the immunomodulatory activity of MAPK pathway inhibitors in BRAF-mutant gliomas.

Rapid Estimation of Entire Brain Strain Using Deep Learning Models

OBJECTIVE

Many recent studies have suggested that brain deformation resulting from a head impact is linked to the corresponding clinical outcome, such as mild traumatic brain injury (mTBI). Even though several finite element (FE) head models have been developed and validated to calculate brain deformation based on impact kinematics, the clinical application of these FE head models is limited due to the time-consuming nature of FE simulations. This work aims to accelerate the process of brain deformation calculation and thus improve the potential for clinical applications.

METHODS

We propose a deep learning head model with a five-layer deep neural network and feature engineering, and trained and tested the model on 2511 total head impacts from a combination of head model simulations and on-field college football and mixed martial arts impacts.

RESULTS

The proposed deep learning head model can calculate the maximum principal strain (Green Lagrange) for every element in the entire brain in less than 0.001s with an average root mean squared error of 0.022, and with a standard deviation of 0.001 over twenty repeats with random data partition and model initialization.

CONCLUSION

Trained and tested using the dataset of 2511 head impacts, this model can be applied to various sports in the calculation of brain strain with accuracy, and its applicability can even further be extended by incorporating data from other types of head impacts.

SIGNIFICANCE

In addition to the potential clinical application in real-time brain deformation monitoring, this model will help researchers estimate the brain strain from a large number of head impacts more efficiently than using FE models.

Matrix Stiffness Modulates Patient-Derived Glioblastoma Cell Fates in Three-Dimensional Hydrogels

Cancer progression is known to be accompanied by changes in tissue stiffness. Previous studies have primarily employed immortalized cell lines and 2D hydrogel substrates, which do not recapitulate the 3D tumor niche. How matrix stiffness affects patient-derived cancer cell fate in 3D remains unclear. In this study, we report a matrix metalloproteinase-degradable poly(ethylene-glycol)-based hydrogel platform with brain-mimicking biochemical cues and tunable stiffness (40-26,600 Pa) for 3D culture of patient-derived glioblastoma xenograft (PDTX GBM) cells. Our results demonstrate that decreasing hydrogel stiffness enhanced PDTX GBM cell proliferation, and hydrogels with stiffness 240 Pa and below supported robust PDTX GBM cell spreading in 3D. PDTX GBM cells encapsulated in hydrogels demonstrated higher drug resistance than 2D control, and increasing hydrogel stiffness further enhanced drug resistance. Such 3D hydrogel platforms may provide a valuable tool for mechanistic studies of the role of niche cues in modulating cancer progression for different cancer types.

White Matter Tract-Oriented Deformation Is Dependent on Real-Time Axonal Fiber Orientation

Traumatic axonal injury (TAI) is a critical public health issue with its pathogenesis remaining largely elusive. Finite element (FE) head models are promising tools to bridge the gap between mechanical insult, localized brain response, and resultant injury. In particular, the FE-derived deformation along the direction of white matter (WM) tracts (i.e., tract-oriented strain) has been shown to be an appropriate predictor for TAI. The evolution of fiber orientation in time during the impact and its potential influence on the tract-oriented strain remains unknown, however. To address this question, the present study leveraged an embedded element approach to track real-time fiber orientation during impacts. A new scheme to calculate the tract-oriented strain was proposed by projecting the strain tensors from pre-computed simulations along the temporal fiber direction instead of its static counterpart directly obtained from diffuse tensor imaging. The results revealed that incorporating the real-time fiber orientation not only altered the direction but also amplified the magnitude of the tract-oriented strain, resulting in a generally more extended distribution and a larger volume ratio of WM exposed to high deformation along fiber tracts. These effects were exacerbated with the impact severities characterized by the acceleration magnitudes. Results of this study provide insights into how best to incorporate fiber orientation in head injury models and derive the WM tract-oriented deformation from computational simulations, which is important for furthering our understanding of the underlying mechanisms of TAI.

A Computational Study of Liquid Shock Absorption for Prevention of Traumatic Brain Injury

Mild traumatic brain injury (mTBI), more colloquially known as concussion, is common in contact sports such as American football, leading to increased scrutiny of head protective gear. Standardized laboratory impact testing, such as the yearly National Football League (NFL) helmet test, is used to rank the protective performance of football helmets, motivating new technologies to improve the safety of helmets relative to existing equipment. In this work, we hypothesized that a helmet which transmits a nearly constant minimum force will result in a reduced risk of mTBI. To evaluate the plausibility of this hypothesis, we first show that the optimal force transmitted to the head, in a reduced order model of the brain, is in fact a constant force profile. To simulate the effects of a constant force within a helmet, we conceptualize a fluid-based shock absorber system for use within a football helmet. We integrate this system within a computational helmet model and simulate its performance on the standard NFL helmet test impact conditions. The simulated helmet is compared with other helmet designs with different technologies. Computer simulations of head impacts with liquid shock absorption predict that, at the highest impact speed (9.3 m/s), the average brain tissue strain is reduced by 27.6% ± 9.3 compared to existing helmet padding when tested on the NFL helmet protocol. This simulation-based study puts forth a target benchmark for the future design of physical manifestations of this technology.

An Analysis of Public Interest in Elective Neurosurgical Procedures During the COVID-19 Pandemic Through Online Search Engine Trends

OBJECTIVE

In the wake of the COVID-19 pandemic, the Centers for Medicare & Medicaid Services (CMS) has recommended the temporary cessation of all elective surgeries. The effects on patients' interest of elective neurosurgical procedures are currently unexplored.

METHODS

Using Google Trends, search terms of 7 different neurosurgical procedure categories (trauma, spine, tumor, movement disorder, epilepsy, endovascular, and miscellaneous) were assessed in terms of relative search volume (RSV) between January 2015 and September 2020. Analyses of search terms were performed for over the short term (February 18, 2020, to April 18, 2020), intermediate term (January 1, 2020, to May 31, 2020), and long term (January 2015 to September 2020). State-level interest during phase I reopening (April 28, 2020, to May 31, 2020) was also evaluated.

RESULTS

In the short term, RSVs of 4 categories (epilepsy, movement disorder, spine, and tumor) were significantly lower in the post-CMS announcement period. In the intermediate term, RSVs of 5 categories (miscellaneous, epilepsy, movement disorder, spine, and tumor) were significantly lower in the post-CMS announcement period. In the long term, RSVs of nearly all categories (endovascular, epilepsy, miscellaneous, movement disorder, spine, and tumor) were significantly lower in the post-CMS announcement period. Only the movement disorder procedure category had significantly higher RSV in states that reopened early.

CONCLUSIONS

With the recommendation for cessation of elective surgeries, patient interests in overall elective neurosurgical procedures have dropped significantly. With gradual reopening, there has been a resurgence in some procedure types. Google Trends has proven to be a useful tracker of patient interest and may be used by neurosurgical departments to facilitate outreach strategies.

IMG-13. MRI-BASED RADIOMICS PROGNOSTIC MARKERS OF POSTERIOR FOSSA EPENDYMOMA

PURPOSE

Posterior fossa ependymomas (PFE) are common pediatric brain tumors often assessed with MRI before surgery. Advanced radiomic analysis show promise in stratifying risk and outcome in other pediatric brain tumors. Here, we extracted high-dimensional MRI features to identify prognostic, image-based, radiomics markers of PFE and compared its performance to clinical variables.

METHODS

93 children from five centers (median age=3.3yrs; 59 males; mean PFS=50mos) were included. Tumor volumes were manually contoured on T1-post contrast and T2-weighted MRI for PyRadiomics feature extraction. Features include first-order statistics, size, shape, and texture metrics calculated on the original, log-sigma, and wavelet transformed images. Progression free survival (PFS) served as outcome. 10-fold cross-validation of a LASSO Cox regression was used to predict PFS. Model performance was analyzed and concordance metric (C) was determined using clinical variable (age at diagnosis and sex) only, radiomics only, and radiomics plus clinical variable.

RESULTS

Six radiomic features were selected (all T1): 1 first-order kurtosis (log-sigma) and 5 texture features (3 wavelet, 2 original). This model demonstrated significantly higher performance than a clinical model alone (C: 0.69 vs 0.58, p<0.001). Adding clinical features to the radiomic features didn’t improve prediction (p=0.67). For patients with molecular subtyping (n=48), adding this feature to the clinical plus radiomics models significantly improved performance over clinical features alone (C = 0.79 vs. 0.66, p=0.02). Further validation and model refinement with additional datasets are ongoing.

CONCLUSION

Our pilot study shows potential role for MRI-based radiomics and machine learning for PFE risk stratification and as radiographic biomarkers.

MODL-26. CHILDREN’S BRAIN TUMOR NETWORK: ACCELERATING RESEARCH THROUGH COLLABORATION AND OPEN-SCIENCE

The Children’s Brain Tumor Network (formerly known as Children’s Brain Tumor Consortium- CBTTC) is a global organization pioneering a model of open-science medical research to improve treatment and discover cures. Started in 2011, our objective was to utilize a regulatory, agreement, and governance architecture to remove existing research barriers that slowed down the pace of research and collaboration. Our network now includes 17 institutions working together to empower research. As of December 2019, over 3,600 subjects have been enrolled resulting in collection of over 45,000 specimens. Clinical data collection is longitudinal and includes medical history, diagnosis, treatment, pathology slides and reports, radiology imaging and reports, and outcome data. The tissue is collected flash-frozen, in freezing media, and fresh for the generation of pre-clinical models including cell lines. Blood is collected from the subject, with blood or saliva collected from the parents for germline comparison. Additionally, the Children’s Brain Tumor Network- Pediatric Brain Tumor Atlas has generated 952 WGS and RNAseq, 221 proteomics, with annotated clinical data. All of this data, both generated raw and processed data, has been made available broadly to the scientific community via cloud-based platforms, including the Gabriella Miller Kids First Data Resource Portal, Cavatica, and PedCbioportal. As of January 2020, we have 45 approved biospecimen requests and 80 genomic/molecular data requests. In summary, the Children’s Brain Tumor Network’s goal is to accelerate the pace of discovery by providing resources and expanding the network of scientists working towards a cure.

IMG-10. MRI-BASED RADIOMIC PROGNOSTIC MARKERS OF DIFFUSE MIDLINE GLIOMA

BACKGROUND

Diffuse midline gliomas (DMG) are lethal pediatric brain tumors with dismal prognoses. Presently, MRI is the mainstay of disease diagnosis and surveillance. We aimed to identify prognostic image-based radiomics markers of DMG and compare its performance to clinical variables at presentation.

METHODS

104 treatment-naïve DMG MRIs from five centers were used (median age=6.5yrs; 18 males, median OS=11mos). We isolated tumor volumes of T1-post-contrast (T1gad) and T2-weighted (T2) MRI for PyRadiomics high-dimensional feature extraction. 900 features were extracted on each image, including first order statistics, 2D/3D Shape, Gray Level Co-occurrence Matrix, Gray Level Run Length Matrix, Gray Level Size Zone Matrix, Neighboring Gray tone Difference Matrix, and Gray Level Dependence Matrix, as defined by Imaging Biomarker Standardization Initiative. Overall survival (OS) served as outcome. 10-fold cross-validation of LASSO Cox regression was used to predict OS. We analyzed model performance using clinical variable (age at diagnosis and sex) only, radiomics only, and radiomics plus clinical variable. Concordance metric was used to assess the Cox model.

RESULTS

Nine radiomic features were selected from T1gad (2 texture wavelet) and T2 (5 first-order features (1 original, 4 wavelet), 2 texture features (1 wavelet, 1 log-sigma). This model demonstrated significantly higher performance than a clinical model alone (C: 0.68 vs 0.59, p&lt;0.001). Adding clinical features to radiomic features slightly improved prediction, but was not significant (C=0.70, p=0.06).

CONCLUSION

Our pilot study shows a potential role for MRI-based radiomics and machine learning for DMG risk stratification and as image-based biomarkers for clinical therapy trials.

RARE-11. QUANTITATIVE MR IMAGING FEATURES ASSOCIATED WITH UNIQUE TRANSCRIPTIONAL CHARACTERISTICS IN PEDIATRIC ADAMANTINOMATOUS CRANIOPHARYNGIOMA: A POTENTIAL GUIDE FOR THERAPY

METHODS

Through the Advancing Treatment for Pediatric Craniopharyngioma (ATPC) consortium we accumulated preoperative MRIs and tumor RNA for 50 unique ACP patients. MRIs were assessed quantitatively for 28 different features and analyzed using Multiple Factor Analysis (MFA) and optimal clustering was determined via maximization of Bayesian Information Criterion (BIC). Following bulk RNAseq, differential expression and pathway enrichment were performed using standard methodologies (i.e., DESeq2 and GSEA).

RESULTS

MRI features were well represented in the first 3 dimensions of MFA (variance explained=67.32%); specifically tumor/cyst size, ventricular size, and cyst fluid diffusivity. Using this three-way axis, we identified 3 patient subgroups. Transcriptional differences between these subgroups indicated one group was enriched for DNA damage response and MYC related pathways, one group enriched for SHH, and one group enriched for WNT/β-catenin and EMT-related pathways.

CONCLUSION

This preliminary work suggests that there may be unique gene expression variants within ACP, which may be identified preoperatively using easily quantifiable MRI parameters. These radiogenomic signatures could provide prognostic information and/or guidance in the selection of antitumor therapies for children with ACP.

IMG-22. A DEEP LEARNING MODEL FOR AUTOMATIC POSTERIOR FOSSA PEDIATRIC BRAIN TUMOR SEGMENTATION: A MULTI-INSTITUTIONAL STUDY

BACKGROUND

Brain tumors are the most common solid malignancies in childhood, many of which develop in the posterior fossa (PF). Manual tumor measurements are frequently required to optimize registration into surgical navigation systems or for surveillance of nonresectable tumors after therapy. With recent advances in artificial intelligence (AI), automated MRI-based tumor segmentation is now feasible without requiring manual measurements. Our goal was to create a deep learning model for automated PF tumor segmentation that can register into navigation systems and provide volume output.

METHODS

720 pre-surgical MRI scans from five pediatric centers were divided into training, validation, and testing datasets. The study cohort comprised of four PF tumor types: medulloblastoma, diffuse midline glioma, ependymoma, and brainstem or cerebellar pilocytic astrocytoma. Manual segmentation of the tumors by an attending neuroradiologist served as “ground truth” labels for model training and evaluation. We used 2D Unet, an encoder-decoder convolutional neural network architecture, with a pre-trained ResNet50 encoder. We assessed ventricle segmentation accuracy on a held-out test set using Dice similarity coefficient (0–1) and compared ventricular volume calculation between manual and model-derived segmentations using linear regression.

RESULTS

Compared to the ground truth expert human segmentation, overall Dice score for model performance accuracy was 0.83 for automatic delineation of the 4 tumor types.

CONCLUSIONS

In this multi-institutional study, we present a deep learning algorithm that automatically delineates PF tumors and outputs volumetric information. Our results demonstrate applied AI that is clinically applicable, potentially augmenting radiologists, neuro-oncologists, and neurosurgeons for tumor evaluation, surveillance, and surgical planning.

QOL-22. MACHINE-LEARNING INFERENCE MAY PREDICT QUALITY OF LIFE SUBGROUPS OF ADAMANTINOMATOUS CRANIOPHARYNGIOMA

BACKGROUND

Due to disease and/or treatment-related injury, such as hypothalamic, visual, and endocrine damage, quality of life (QoL) scores after childhood-onset Adamantinomatous Craniopharyngioma (ACP) are among the lowest of all pediatric brain tumors. Decision-making regarding management would be aided by more complete understanding of a patients likely QoL trajectory following intervention.

METHODS

We retrospectively analyzed caregiver and patient-reported QoL-instruments from the first 50 patients (ages 1–17 years at diagnosis) enrolled in the international Advancing Treatment for Pediatric Craniopharyngioma (ATPC) consortium. Surveys included 205 pediatric-relevant questions and were completed at diagnosis, and 1- and 12-months following diagnosis. Using Multiple Correspondence Analysis (MCA), these categorical QoL surveys were interrogated to identify time-dependent patient subgroups. Additionally, custom deep learning classifiers were developed using Google’s TensorFlow framework.

RESULTS

By representing QoL data in the reduced dimensionality of MCA-space, we identified QoL subgroups that either improved or declined over time. We assessed differential trends in QoL responses to identify variables that were subgroup specific (Kolmogorov-Smirnov p-value < 0.1; n=20). Additionally, our optimized deep learning classifier achieved a mean 5-fold cross-validation area under precision-recall curve score > 0.99 when classifying QoL subgroups at 12 month follow-up, using only baseline data.

CONCLUSIONs

This work demonstrates the existence of time-dependent QoL-based ACP subgroups that can be inferred at time-of-diagnosis via machine learning analyses of baseline survey responses. The ability to predict an ACP patient’s QoL trajectory affords caregivers valuable information that can be leveraged to maximize that patient’s psychosocial state and therefore improve overall therapy.

A comparative study of brain tumor cells from different age and anatomical locations using 3D biomimetic hydrogels

Brain tumors exhibit vast genotypic and phenotypic diversity depending on patient age and anatomical location. Hydrogels hold great promise as 3D in vitro models for studying brain tumor biology and drug screening, yet previous studies were limited to adult glioblastoma cells, and most studies used immortalized cell lines. Here we report a hydrogel platform that supports the proliferation and invasion of patient-derived brain tumor cell cultures (PDCs) isolated from different patient age groups and anatomical locations. Hydrogel stiffness was tuned by varying poly(ethylene-glycol) concentration. Cell adhesive peptide (CGRDS), hyaluronic acid, and MMP-cleavable crosslinkers were incorporated to facilitate cell adhesion and cell-mediated degradation. Three PDC lines were compared including adult glioblastoma cells (aGBM), pediatric glioblastoma cells (pGBM), and diffuse pontine intrinsic glioma (DIPG). A commonly used immortalized adult glioblastoma cell line U87 was included as a control. PDCs displayed stiffness-dependent behavior, with 40 Pa hydrogel promoting faster tumor proliferation and invasion. Adult GBM cells exhibited faster proliferation than pediatric GBM, and DIPG showed slowest proliferation. These results suggest both patient age and tumor location affects brain tumor behaviors. Adult GBM PDCs also exhibited very different cell proliferation and morphology from U87. The hydrogel reported here can provide a useful tool for future studies to better understand how age and anatomical locations impacts brain tumor progression using 3D in vitro models.