Search

Neuroblastomas harbor ALK aberrations clinically resistant to crizotinib yet sensitive pre-clinically to the third-generation ALK inhibitor lorlatinib. We conducted a first-in-child study evaluating lorlatinib with and without chemotherapy in children and adults with relapsed or refractory ALK-driven neuroblastoma. The trial is ongoing, and we report here on three cohorts that have met pre-specified primary endpoints: lorlatinib as a single agent in children (12 months to 123I-metaiodobenzylguanidine (MIBG) response. Lorlatinib was evaluated at 45–115 mg/m2/dose in children and 100–150 mg in adults. Common adverse events (AEs) were hypertriglyceridemia (90%), hypercholesterolemia (79%) and weight gain (87%). Neurobehavioral AEs occurred mainly in adults and resolved with dose hold/reduction. The RP2D of lorlatinib with and without chemotherapy in children was 115 mg/m2. The single-agent adult RP2D was 150 mg. The single-agent response rate (complete/partial/minor) for NCT03107988.

PURPOSE Although chemoimmunotherapy is widely used for treatment of children with relapsed high-risk neuroblastoma (HRNB), little is known about timing, duration, and evolution of response after irinotecan/temozolomide/dinutuximab/granulocyte-macrophage colony-stimulating factor (I/T/DIN/GM-CSF) therapy. PATIENTS AND METHODS Patients eligible for this retrospective study were age < 30 years at diagnosis of HRNB and received ≥ 1 cycle of I/T/DIN/GM-CSF for relapsed or progressive disease. Patients with primary refractory disease who progressed through induction were excluded. Responses were evaluated using the International Neuroblastoma Response Criteria. RESULTS One hundred forty-six patients were included. Tumors were MYCN-amplified in 50 of 134 (37%). Seventy-one patients (49%) had an objective response to I/T/DIN/GM-CSF (objective response; 29% complete response, 14% partial response [PR], 5% minor response [MR], 21% stable disease [SD], and 30% progressive disease). Of patients with SD or better at first post-I/T/DIN/GM-CSF disease evaluation, 22% had an improved response per International Neuroblastoma Response Criteria on subsequent evaluation (13% of patients with initial SD, 33% with MR, and 41% with PR). Patients received a median of 4.5 (range, 1-31) cycles. The median progression-free survival (PFS) was 13.1 months, and the 1-year PFS and 2-year PFS were 50% and 28%, respectively. The median duration of response was 15.9 months; the median PFS off all anticancer therapy was 10.4 months after discontinuation of I/T/DIN/GM-CSF. CONCLUSION Approximately half of patients receiving I/T/DIN/GM-CSF for relapsed HRNB had objective responses. Patients with initial SD were unlikely to have an objective response, but > 1 of 3 patients with MR/PR on first evaluation ultimately had complete response. I/T/DIN/GM-CSF was associated with extended PFS in responders both during and after discontinuation of treatment. This study establishes a new comparator for response and survival in patients with relapsed HRNB.

High-risk neuroblastoma patients with end-induction residual disease commonly receive post-induction therapy in an effort to increase survival by improving the response before autologous stem cell transplantation (ASCT). The authors conducted a multicenter, retrospective study to investigate the efficacy of this approach.Patients diagnosed between 2008 and 2018 without progressive disease with a partial response or worse at end-induction were stratified according to the post-induction treatment: 1) no additional therapy before ASCT (cohort 1), 2) post-induction "bridge" therapy before ASCT (cohort 2), and 3) post-induction therapy without ASCT (cohort 3). χThe study cohort consisted of 201 patients: cohort 1 (n = 123), cohort 2 (n = 51), and cohort 3 (n = 27). Although the end-induction response was better for cohort 1 than cohorts 2 and 3, the outcomes for cohorts 1 and 2 were not significantly different (P = .77 for EFS and P = .85 for OS). Inferior outcomes were observed for cohort 3 (P.001 for EFS and P = .06 for OS). Among patients with end-induction stable metastatic disease, 3-year EFS was significantly improved for cohort 2 versus cohort 1 (P = .04). Cohort 3 patients with a complete response at metastatic sites after post-induction therapy had significantly better 3-year EFS than those with residual metastatic disease (P = .01).Prospective studies to confirm the benefits of bridge treatment and the prognostic significance of metastatic response observed in this study are warranted.

Loss of GBP1 expression does not impact PSaRC318 cell migration.

Prevalence of somatic DNA damage repair gene variants in Ewing cell lines included in original studies of PARP inhibition.

Ewing sarcoma is a fusion oncoprotein–driven primary bone tumor. A subset of patients (∼10%) with Ewing sarcoma are known to harbor germline variants in a growing number of genes involved in DNA damage repair. We recently reported our discovery of a germline mutation in the DNA damage repair protein BARD1 (BRCA1-associated RING domain-1) in a patient with Ewing sarcoma. BARD1 is recruited to the site of DNA double stranded breaks via the PARP protein and plays a critical role in DNA damage response pathways including homologous recombination. We thus questioned the impact of BARD1 loss on Ewing cell sensitivity to DNA damage and the Ewing sarcoma transcriptome. We demonstrate that PSaRC318 cells, a novel patient-derived cell line harboring a pathogenic BARD1 variant, are sensitive to PARP inhibition and by testing the effect of BARD1 depletion in additional Ewing sarcoma cell lines, we confirm that BARD1 loss enhances cell sensitivity to PARP inhibition plus radiation. In addition, RNA-sequencing analysis revealed that loss of BARD1 results in the upregulation of GBP1 (guanylate-binding protein 1), a protein whose expression is associated with variable response to therapy depending on the adult carcinoma subtype examined. Here, we demonstrate that GBP1 contributes to the enhanced sensitivity of BARD1-deficient Ewing cells to DNA damage. Together, our findings demonstrate the impact of loss-of function mutations in DNA damage repair genes, such as BARD1, on Ewing sarcoma treatment response.Significance:This work provides preclinical support for the inclusion of pediatric patients with advanced Ewing sarcoma and pathogenic germline variants in BARD1 in future clinical trials testing novel agents inducing DNA damage/targeting DNA damage repair.

Nanopore Sensitivity/Specificity details

All supplementary data except table S3A and S3B

Purpose:Pediatric high-grade glioma (pHGG) diagnosis portends poor prognosis and therapeutic monitoring remains difficult. Tumors release cell-free tumor DNA (cf-tDNA) into cerebrospinal fluid (CSF), allowing for potential detection of tumor-associated mutations by CSF sampling. We hypothesized that direct, electronic analysis of cf-tDNA with a handheld platform (Oxford Nanopore MinION) could quantify patient-specific CSF cf-tDNA variant allele fraction (VAF) with improved speed and limit of detection compared with established methods.Experimental Design:We performed ultra-short fragment (100–200 bp) PCR amplification of cf-tDNA for clinically actionable alterations in CSF and tumor samples from patients with pHGG (n = 12) alongside nontumor CSF (n = 6). PCR products underwent rapid amplicon-based sequencing by Oxford Nanopore Technology (Nanopore) with quantification of VAF. Additional comparison to next-generation sequencing (NGS) and droplet digital PCR (ddPCR) was performed.Results:Nanopore demonstrated 85% sensitivity and 100% specificity in CSF samples (n = 127 replicates) with 0.1 femtomole DNA limit of detection and 12-hour results, all of which compared favorably with NGS. Multiplexed analysis provided concurrent analysis of H3.3A (H3F3A) and H3C2 (HIST1H3B) mutations in a nonbiopsied patient and results were confirmed by ddPCR. Serial CSF cf-tDNA sequencing by Nanopore demonstrated correlation of radiological response on a clinical trial, with one patient showing dramatic multi-gene molecular response that predicted long-term clinical response.Conclusions:Nanopore sequencing of ultra-short pHGG CSF cf-tDNA fragments is feasible, efficient, and sensitive with low-input samples thus overcoming many of the barriers restricting wider use of CSF cf-tDNA diagnosis and monitoring in this patient population.

Background:Bloodstream infections (BSIs) are a frequent cause of morbidity in patients with acute myeloid leukemia (AML), due in part to the presence of central venous access devices (CVADs) required to deliver therapy.Objective:To determine the differential risk of bacterial BSI during neutropenia by CVAD type in pediatric patients with AML.Methods:We performed a secondary analysis in a cohort of 560 pediatric patients (1,828 chemotherapy courses) receiving frontline AML chemotherapy at 17 US centers. The exposure was CVAD type at course start: tunneled externalized catheter (TEC), peripherally inserted central catheter (PICC), or totally implanted catheter (TIC). The primary outcome was course-specific incident bacterial BSI; secondary outcomes included mucosal barrier injury (MBI)-BSI and non-MBI BSI. Poisson regression was used to compute adjusted rate ratios comparing BSI occurrence during neutropenia by line type, controlling for demographic, clinical, and hospital-level characteristics.Results:The rate of BSI did not differ by CVAD type: 11 BSIs per 1,000 neutropenic days for TECs, 13.7 for PICCs, and 10.7 for TICs. After adjustment, there was no statistically significant association between CVAD type and BSI: PICC incident rate ratio [IRR] = 1.00 (95% confidence interval [CI], 0.75–1.32) and TIC IRR = 0.83 (95% CI, 0.49–1.41) compared to TEC. When MBI and non-MBI were examined separately, results were similar.Conclusions:In this large, multicenter cohort of pediatric AML patients, we found no difference in the rate of BSI during neutropenia by CVAD type. This may be due to a risk-profile for BSI that is unique to AML patients.

Fibrous dysplasia of the mandible typically begins during toddler years and culminates during puberty. These lesions may cause jaw disfigurement and may not be amendable to surgery. Imatinib successfully has treated cherubism associated with SH3BP2 mutations, but similar lesions can present in other conditions such as Noonan syndrome. We report diagnosis of Noonan syndrome caused by a PTPN11 activating mutation and successful treatment of the fibrous dysplasia of the mandible with imatinib.

During COVID-19, public health measures including masks and social distancing decreased viral upper respiratory infections (URI). Upper respiratory infections are the most common infectious etiology for low-risk pediatric febrile neutropenia (FN). This single-center, quasi-experimental, pre-post study was designed to understand the impact of public health measures on FN admissions and outcomes in the general pediatric oncology population during the COVID (March 2020–February 2021) vs. pre-COVID era (January 2018–February 2020) and their respective respiratory seasons (November–February). episodes were risk-stratified using a tool recommended by the Children’s Oncology Group. Descriptive and bivariate statistics were used to compare admission characteristics and outcomes. Comparing respiratory seasons, the Covid-era season had 60% fewer URI diagnoses (5/12), while high-risk episodes (63.6% [28/44] vs. 44.2% [23/52]) and intensive care admissions (18.2% [8/44] vs. 3.8% [2/52]) increased. Between eras, URIs were lower in the COVID-era (10.8% [16/148] vs. 19.9% [67/336]; p = 0.01), but admission characteristics and severe outcomes were not different. the impact of public health measures was most prominent during the respiratory season. Despite decreased incidence of URIs, the overall admission characteristics and severe outcomes were minimally impacted due to the brevity of respiratory seasons, but larger studies are warranted.

Posterior fossa ependymomas A confer the worst prognosis among all subtypes. They demonstrate distinct epigenetic changes, which can be targeted with epigenetic modifiers like histone deacetylase inhibitors (Vorinostat). We describe a 3-year-old male diagnosed with a posterior fossa ependymoma who had a number of recurrences requiring multimodal therapy. Molecular analysis demonstrated a BCL-6 corepressor mutation, and methylation profiling matched with posterior fossa ependymomas A. He received craniospinal irradiation and focal boost with Vorinostat. Serial imaging after irradiation revealed a progressively decreasing tumor burden with nearly complete resolution of disease at 15 months. Histone deacetylase inhibitors demonstrate promise in treatment of carefully selected cases of ependymoma.

PDGFRA has been shown to be commonly altered in high-grade gliomas (HGGs), including histone 3 lysine 27-mutated diffuse midline gliomas (H3K27M DMG), a disease with almost no long-term survivors. Here, we performed comprehensive genomic and transcriptomic analysis of 260 high-grade glioma cases, which revealed PDGFRA genomic alterations (mutations and/or amplifications) in 13% of patients. H3K27M DMGs had significantly higher PDGFRA expression compared to H3 wild-type tumors, and PDGFRA gene amplification resulted in even higher expression levels in H3K27M DMGs as well as H3 wild-type HGGs. We tested a panel of patient- derived pHGG/H3K27M DMG models against a range of PDGFRA inhibitors, including avapritinib, a potent small molecule inhibitor with relatively selective activity against both wild-type and mutant PDGFRA. Avapritinib showed supra-micromolar blood-brain barrier penetration in our pre-clinical models and demonstrated significant survival impact in an aggressive patient-derived H3K27M DMG mouse xenograft model. Finally, building on this preclinical activity, we report here the first clinical experience using avapritinib in eight pediatric and young adult patients with high-grade glioma (H3K27M DMG and/or PDGFRA altered). Avapritinib has thus far been well tolerated with no significant acute toxicities. Most importantly, our preliminary data reveal radiographic response evaluated by RAPNO criteria in 50% of patients, a striking outcome rarely seen in this patient population. In summary, we report that avapritinib is a selective, CNS-penetrant small molecule inhibitor of PDGFRA that shows potent activity in preclinical models and produces promising clinical responses with good tolerability in patients with high-grade glioma. This suggests a promising role for avapritinib therapy in this population with previously dismal outcomes. Citation Format: Lisa Mayr, Maria Trissal, Kallen Schwark, Jenna Labelle, Andrew Groves, Julia Furtner-Srajer, Jeffrey Supko, Liesa Weiler-Wichtl, Olivia Hack, Jacob Rozowsky, Joana G. Marques, Eshini Pandatharatna, Ulrike Leiss, Verena Rosenmayr, Frank Dubois, Noah F. Greenwald, Sibylle Madlener, Armin S. Guntner, Hana Pálová, Natalia Stepien, Daniela Lötsch-Gojo, Christian Dorfer, Karin Dieckmann, Andreas Peyrl, Amedeo A. Azizi, Alicia Baumgartner, Ondřej Slabý, Petra Pokorná, Pratiti Bandopadhayay, Rameen Beroukhim, Keith Ligon, Christof Kramm, Annika Bronsema, Simon Bailey, Ana Guerreiro Stücklin, Sabine Mueller, David T. Jones, Natalie Jäger, Jaroslav Štěrba, Leonhard Müllauer, Christine Haberler, Chandan Kumar-Sinha, Arul Chinnaiyan, Rajen Mody, Mary Skrypek, Nina Martinez, Daniel C. Bowers, Carl Koschmann, Johannes Gojo, Mariella Filbin. Clinical response to the PDGFRα inhibitor avapritinib in high-grade glioma patients. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5719.

Purpose: Pediatric high-grade glioma (pHGG) diagnosis portends poor prognosis and therapeutic monitoring remains difficult. Tumors release cell-free tumor DNA (cf-tDNA) into cerebrospinal fluid (CSF), allowing for potential detection of tumor-associated mutations by CSF sampling. We hypothesized that direct, electronic analysis of cf-tDNA with a handheld platform (Oxford Nanopore MinION) could quantify patient-specific CSF cf-tDNA variant allele fraction (VAF) with improved speed and limit of detection compared with established methods. Experimental Design: We performed ultra-short fragment (100–200 bp) PCR amplification of cf-tDNA for clinically actionable alterations in CSF and tumor samples from patients with pHGG (n = 12) alongside nontumor CSF (n = 6). PCR products underwent rapid amplicon-based sequencing by Oxford Nanopore Technology (Nanopore) with quantification of VAF. Additional comparison to next-generation sequencing (NGS) and droplet digital PCR (ddPCR) was performed. Results: Nanopore demonstrated 85% sensitivity and 100% specificity in CSF samples (n = 127 replicates) with 0.1 femtomole DNA limit of detection and 12-hour results, all of which compared favorably with NGS. Multiplexed analysis provided concurrent analysis of H3.3A (H3F3A) and H3C2 (HIST1H3B) mutations in a nonbiopsied patient and results were confirmed by ddPCR. Serial CSF cf-tDNA sequencing by Nanopore demonstrated correlation of radiological response on a clinical trial, with one patient showing dramatic multi-gene molecular response that predicted long-term clinical response. Conclusions: Nanopore sequencing of ultra-short pHGG CSF cf-tDNA fragments is feasible, efficient, and sensitive with low-input samples thus overcoming many of the barriers restricting wider use of CSF cf-tDNA diagnosis and monitoring in this patient population.

Patients with H3K27M-mutated diffuse midline glioma (DMG) have no proven effective therapies beyond radiation. ONC201, a DRD2 antagonist and mitochondrial ClpP agonist, has shown promise in this population. Clinical and genetic variables associated with ONC201 response in H3K27M-mutant DMG continue to be investigated. A combined clinical and genetic study evaluated patients with H3K27M-DMG treated with single-agent ONC201 at the established phase 2 dose. Clinical outcomes of patients treated on two recently completed multi-site clinical studies (NCT03416530 and NCT03134131, n = 75) were compared with historical control data from patients with confirmed H3K27M-DMG (n = 391 total, n = 119 recurrent). Patients treated with ONC201 monotherapy following initial radiation, but prior to recurrence, demonstrated a median overall survival (OS) of 25.6 months from diagnosis and recurrent patients demonstrated a median OS of 16.2 months from recurrence, both of these more than doubling historical outcomes. Using a Cox model to correct for age, gender and tumor location, OS of ONC201-treated patients with H3K27M-mutant tumors remained significantly better than non-ONC201-treated historical controls (p = 0.0001). A survival and radiographic analysis based on tumor location, revealed stronger responses in thalamic patients. In patients with thalamic tumors treated after initial radiation (n = 16), median OS was not reached with median follow up of 22.1 months (historical control median OS of 12.5 months, n = 83, p = 0.0001). Significant correlations were found between baseline cerebral blood flow (CBF) on perfusion imaging and OS (Pearson’s r = 0.75, p = 0.003) and between nrCBF and PFS (r = 0.77, p = 0.002). Baseline tumor sequencing from treated patients (n = 20) demonstrates EGFR mutation (n = 3) and high EGFR expression as a marker of resistance and improved response in tumors with MAPK-pathway alterations (n = 5). In conclusion, ONC201 demonstrates unprecedented clinical and radiographic efficacy in H3K27M-mutant DMG with outcomes enriched in patients with thalamic tumors, treatment prior to recurrence, MAPK-pathway alterations, and patients with relatively high CBF.

Retinoblastoma is the most common ocular tumor of childhood with cure rates exceeding 95%. Patients with high-risk features typically relapse within 3 years of diagnosis. We report a patient with low-risk bilateral retinoblastoma who suffered systemic relapse after eight years. His disease at first relapse was chemosensitive without PET avidity or bone marrow disease following therapy. Six months later, he experienced an isolated CNS relapse and succumbed to refractory disease. “Oncoseq” exome sequencing confirmed the presence of germline RB mutation among all tissues as well as somatic changes which may provide insights into the biology of relapse and tumor.

Survival outcomes for relapsed/refractory pediatric acute myeloid leukemia (R/R AML) remain dismal. Epigenetic changes can result in gene expression alterations which are thought to contribute to both leukemogenesis and chemotherapy resistance. We report results from a phase I trial with a dose expansion cohort investigating decitabine and vorinostat in combination with fludarabine, cytarabine, and G-CSF (FLAG) in pediatric patients with R/R AML [NCT02412475]. Thirty-seven patients enrolled with a median age at enrollment of 8.4 (range, 1-20) years. There were no dose limiting toxicities among the enrolled patients, including two patients with Down syndrome. The recommended phase 2 dose of decitabine in combination with vorinostat and FLAG was 10 mg/m2 . The expanded cohort design allowed for an efficacy evaluation and the overall response rate among 35 evaluable patients was 54% (16 complete response (CR) and 3 complete response with incomplete hematologic recovery (CRi)). Ninety percent of responders achieved minimal residual disease (MRD) negativity (

BackgroundPediatric and adult high-grade glioma (HGG) frequently harbor PDGFRA alterations. We hypothesized that co-treatment with everolimus may improve the efficacy of dasatinib in PDGFRα-driven glioma through combinatorial synergism and increased tumor accumulation of dasatinib.MethodsDose response, synergism studies, P-gp inhibition and pharmacokinetic studies were performed on in vitro and in vivo human and mouse models of HGG. Six patients with recurrent PDGFRα-driven glioma were treated with dasatinib and everolimus.ResultsDasatinib effectively inhibited the proliferation of mouse and human primary HGG cells with a variety of PDGFRA alterations. Dasatinib exhibited synergy with everolimus in the treatment of HGG cells at low nanomolar concentrations of both agents, with reduction in mTOR signaling that persists after dasatinib treatment alone. Prolonged exposure to everolimus significantly improved the CNS retention of dasatinib and extended survival of PPK tumor bearing mice. Pediatric patients (n=6) with glioma tolerated this combination without significant adverse events. Recurrent patients (n=4) demonstrated median overall survival of 8.5 months.ConclusionEfficacy of dasatinib treatment of PDGFRα-driven HGG is improved with everolimus and suggests a promising route for improving targeted therapy for this patient population.Trial RegistrationClinicalTrials.gov NCT03352427FundingThe authors thank the patients and their families for participation in this study. CK is supported by NIH/NINDS K08-NS099427-01, the University of Michigan Chad Carr Pediatric Brain Tumor Center, the Chad Tough Foundation, Hyundai Hope on Wheels, Catching up With Jack, Prayers from Maria Foundation, U CAN-CER VIVE FOUNDATION, Morgan Behen Golf Classic, and the DIPG Collaborative. The PEDS-MIONCOSEQ study was supported by grant 1UM1HG006508 from the National Institutes of Health Clinical Sequencing Exploratory Research Award (PI: Arul Chinnaiyan).

PURPOSE The combination of irinotecan, temozolomide, dintuximab, and granulocyte-macrophage colony-stimulating factor (I/T/DIN/GM-CSF) demonstrated activity in patients with relapsed/refractory neuroblastoma in the randomized Children’s Oncology Group ANBL1221 trial. To more accurately assess response rate and toxicity, an expanded cohort was nonrandomly assigned to I/T/DIN/GM-CSF. PATIENTS AND METHODS Patients were eligible at first relapse or first designation of refractory disease. Oral T and intravenous (IV) irinotecan were administered on days 1 to 5 of 21-day cycles. DIN was administered IV (days 2-5), and GM-CSF was administered subcutaneously (days 6-12). The primary end point was objective response, analyzed on an intent-to-treat basis per the International Neuroblastoma Response Criteria. RESULTS Seventeen eligible patients were randomly assigned to I/T/DIN/GM-CSF (February 2013 to March 2015); 36 additional patients were nonrandomly assigned to I/T/DIN/GM-CSF (August 2016 to May 2017). Objective (complete or partial) responses were observed in nine (52.9%) of 17 randomly assigned patients (95% CI, 29.2% to 76.7%) and 13 (36.1%) of 36 expansion patients (95% CI, 20.4% to 51.8%). Objective responses were seen in 22 (41.5%) of 53 patients overall (95% CI, 28.2% to 54.8%); stable disease was also observed in 22 of 53. One-year progression-free and overall survival for all patients receiving I/T/DIN/GM-CSF were 67.9% ± 6.4% (95% CI, 55.4% to 80.5%) and 84.9% ± 4.9% (95% CI, 75.3% to 94.6%), respectively. Two patients did not receive protocol therapy and were evaluable for response but not toxicity. Common grade ≥ 3 toxicities were fever/infection (18 [35.3%] of 51), neutropenia (17 [33.3%] of 51), pain (15 [29.4%] of 51), and diarrhea (10 [19.6%] of 51). One patient met protocol-defined criteria for unacceptable toxicity (grade 4 hypoxia). Higher DIN trough levels were associated with response. CONCLUSION I/T/DIN/GM-CSF has significant antitumor activity in patients with relapsed/refractory neuroblastoma. Study of chemoimmunotherapy in the frontline setting is indicated, as is further evaluation of predictive biomarkers.

Background: Panobinostat demonstrates activity against pediatric cancers in vitro. A phase I trial in children with refractory hematologic malignancies was conducted. Study design: The trial evalua...

Background Diffuse Midline Glioma (DMG) with the H3K27M mutation is a lethal childhood brain cancer, with patients rarely surviving 2 years from diagnosis. Methods We conducted a multi-site Phase 1 trial of the imipridone ONC201 for children with H3K27M-mutant glioma (NCT03416530). Patients enrolled on Arm D of the trial (n = 24) underwent serial lumbar puncture for cell-free tumor DNA (cf-tDNA) analysis and patients on all arms at the University of Michigan underwent serial plasma collection. We performed digital droplet polymerase chain reaction (ddPCR) analysis of cf-tDNA samples and compared variant allele fraction (VAF) to radiographic change (maximal 2D tumor area on MRI). Results Change in H3.3K27M VAF over time (“VAF delta”) correlated with prolonged PFS in both CSF and plasma samples. Nonrecurrent patients that had a decrease in CSF VAF displayed a longer progression free survival (P = .0042). Decrease in plasma VAF displayed a similar trend (P = .085). VAF “spikes” (increase of at least 25%) preceded tumor progression in 8/16 cases (50%) in plasma and 5/11 cases (45.4%) in CSF. In individual cases, early reduction in H3K27M VAF predicted long-term clinical response (>1 year) to ONC201, and did not increase in cases of later-defined pseudo-progression. Conclusion Our work demonstrates the feasibility and potential utility of serial cf-tDNA in both plasma and CSF of DMG patients to supplement radiographic monitoring. Patterns of change in H3K27M VAF over time demonstrate clinical utility in terms of predicting progression and sustained response and possible differentiation of pseudo-progression and pseudo-response.

BackgroundIn the Children’s Oncology Group ANBL1221 phase 2 trial for patients with first relapse/first declaration of refractory high-risk neuroblastoma, irinotecan and temozolomide (I/T) combined with either temsirolimus (TEMS) or immunotherapy (the anti-GD2 antibody dinutuximab (DIN) and granulocyte macrophage colony stimulating factory (GM-CSF)) was administered. The response rate among patients treated with I/T/DIN/GM-CSF in the initial cohort (n=17) was 53%; additional patients were enrolled to permit further evaluation of this chemoimmunotherapy regimen. Potential associations between immune-related biomarkers and clinical outcomes including response and survival were evaluated.MethodsPatients were evaluated for specific immunogenotypes that influence natural killer (NK) cell activity, including killer immunoglobulin-like receptors (KIRs) and their ligands, Fc gamma receptors, and NCR3. Total white cells and leucocyte subsets were assessed via complete blood counts, and flow cytometry of peripheral blood mononuclear cells was performed to assess the potential association between immune cell subpopulations and surface marker expression and clinical outcomes. Appropriate statistical tests of association were performed. The Bonferroni correction for multiple comparisons was performed where indicated.ResultsOf the immunogenotypes assessed, the presence or absence of certain KIR and their ligands was associated with clinical outcomes in patients treated with chemoimmunotherapy rather than I/T/TEMS. While median values of CD161, CD56, and KIR differed in responders and non-responders, statistical significance was not maintained in logistic regression models. White cell and neutrophil counts were associated with differences in survival outcomes, however, increases in risk of event in patients assigned to chemoimmunotherapy were not clinically significant.ConclusionsThese findings are consistent with those of prior studies showing that KIR/KIR-ligand genotypes are associated with clinical outcomes following anti-GD2 immunotherapy in children with neuroblastoma. The current study confirms the importance of KIR/KIR-ligand genotype in the context of I/T/DIN/GM-CSF chemoimmunotherapy administered to patients with relapsed or refractory disease in a clinical trial. These results are important because this regimen is now widely used for treatment of patients at time of first relapse/first declaration of refractory disease. Efforts to assess the role of NK cells and genes that influence their function in response to immunotherapy are ongoing.Trial registration numberNCT01767194.

Tenosynovial giant cell tumors (TSGCT) are a group of rare, benign soft tissue tumors with common histologic and cytogenetic features, with a median age of diagnosis being 47 years. Generally divided into localized and diffuse subtypes, TSGCTs are typically driven by overexpression of macrophage colony stimulating factor receptor-1 (CSF1R). Treatment of TSGCT is tumor resection, followed by radiation therapy in cases of incomplete resection. Even when the tumor is completely removed, recurrence rates can be as high as 30% in some anatomical locations. Here we report the identification of a previously undescribed KRAS p.G12D activating mutation within a pediatric TSGCT patient, who clinically presented with an enlarging right lower extremity mass pathologically consistent with TSGCT. The patient continues to be in remission three years after complete surgical removal. KRAS mutations are usually found in adult cancers, such as lung and pancreatic, as well as giant cell lesion of the jaw. This case demonstrates the utility of integrative clinical sequencing in identifying lesions with aggressive potential and aiding in complex diagnoses.

Risk stratification of pediatric febrile neutropenia (FN) is an established concept; the internal evaluation of a validated clinical decision rules (CDR) tool has not been well-described. In this study, restrictive criteria and procalcitonin were added to a recommended CDR for internal evaluation before implementation. Analysis of 577 FN episodes showed good sensitivity and negative predictive value in predicting blood stream infections (87.3%; 95.6%) and intensive care admissions (97.2%; 99.1%). There were no severe adverse events in low-risk patients with low procalcitonin; procalcitonin identified 3 low-risk patients with serious bacterial infections. The modified CDR with procalcitonin may assist in risk stratification.

Background Diffuse midline gliomas (DMG) are highly invasive brain tumors with rare survival beyond two years past diagnosis and limited understanding of the mechanism behind tumor invasion. Previous reports demonstrate upregulation of the protein ID1 with H3K27M and ACVR1 mutations in DMG, but this has not been confirmed in human tumors or therapeutically targeted. Methods Whole exome, RNA, and ChIP-sequencing was performed on the ID1 locus in DMG tissue. Scratch-assay migration and transwell invasion assays of cultured cells were performed following shRNA-mediated ID1-knockdown. In vitro and in vivo genetic and pharmacologic [cannabidiol (CBD)] inhibition of ID1 on DMG tumor growth was assessed. Patient-reported CBD dosing information was collected. Results Increased ID1 expression in human DMG and in utero electroporation (IUE) murine tumors is associated with H3K27M mutation and brainstem location. ChIP-sequencing indicates ID1 regulatory regions are epigenetically active in human H3K27M-DMG tumors and prenatal pontine cells. Higher ID1-expressing astrocyte-like DMG cells share a transcriptional program with oligo/astrocyte-precursor cells (OAPCs) from the developing human brain and demonstrate upregulation of the migration regulatory protein SPARCL1. Genetic and pharmacologic (CBD) suppression of ID1 decreases tumor cell invasion/migration and tumor growth in H3.3/H3.1K27M PPK-IUE and human DIPGXIIIP* in vivo models of pHGG. The effect of CBD on cell proliferation appears to be non-ID1 mediated. Finally, we collected patient-reported CBD treatment data, finding that a clinical trial to standardize dosing may be beneficial. Conclusions H3K27M-mediated re-activation of ID1 in DMG results in a SPARCL1+ migratory transcriptional program that is therapeutically targetable with CBD.

Diffuse midline gliomas (DMG) are highly invasive brain tumors with rare survival beyond two years past diagnosis. The mechanism behind tumor invasion is currently not well understood. Previous reports demonstrate upregulation of the protein ID1 with H3K27M and ACVR1 mutations in DMG, but this has not been confirmed in human tumors or therapeutically targeted. Whole exome, RNA, and ChIP-sequencing were performed on the ID1 locus in DMG tissue. Scratch-assay migration and transwell invasion assays of cultured cells were performed following shRNA-mediated ID1-knockdown. In vitro and in vivo genetic and pharmacologic [cannabidiol (CBD)] inhibition of ID1 on DMG tumor growth was assessed. Additional in vitro experiments were performed to determine a potential mechanism of action for CBD-mediated effects. Self-reported CBD dosing information was collected from DMG patients. We found that increased ID1 expression in human DMG and in utero electroporation (IUE) murine tumors is associated with H3K27M mutation and brainstem location. ChIP-sequencing indicates a similar epigenetically active state at ID1 regulatory regions in human H3K27M-DMG tumors and prenatal pontine cells. Higher ID1-expressing astrocyte-like DMG cells share a transcriptional program with oligo/astrocyte-precursor cells (OAPCs) from the developing human brain and demonstrate upregulation of the migration regulatory protein SPARCL1. Genetic and pharmacologic (CBD) suppression of ID1 decreases tumor cell migration, tumor growth, and to a lesser extent invasion in both murine IUE and multiple patient-derived in vivo DMG models, improving mouse survival. ID1 knockdown significantly decreases the effect of CBD on migration, tumor growth, and invasion. CBD increases reactive oxygen species production, which also affects DMG cell proliferation in a non-ID1 mediated manner. Overall, we find that H3K27M-mediated reactivation of ID1 in DMG results in a SPARCL1+ migratory transcriptional program that is therapeutically targetable with CBD.

The ETV6-ABL1 fusion is a rare genetic aberration classified as Philadelphia chromosome-like high-risk B-cell precursor acute lymphoblastic leukemia. We present the case of a child with multiply relapsed B-cell precursor acute lymphoblastic leukemia in which next-generation sequencing identified this cryptic fusion, undetected by standard testing, resulting in sustained clinical response to targetted therapy with imatinib. Upon subsequent relapse, repeat next-generation sequencing identified an additional aberration, MLL2-ADCY9, as a possible molecular driver conferring resistance to therapy. This report demonstrates the exciting potential of integrative clinical sequencing in identifying previously undetected actionable findings leading to improved outcomes in pediatric oncology patients.

Children's Oncology Group (COG) has been highly successful in improving childhood cancer survival through well-designed multi-institutional clinical trials. However, our center has recognized a decline in the number of enrollments on COG therapeutic clinical trials over recent years. Our single center, retrospective analysis evaluated in detail the patient enrollment rates, annual number of available clinical trials and reason for nonenrollment over the last decade. We found a 61% decrease in enrollment for phase II to III trials of newly diagnosed patients at our center (2011-2018) along a 29% decrease in the number of open COG studies annually. The primary reason for nonenrollment was unavailability of a suitable trial (76%). We also recognized a decrease in number of adolescent and young adult enrollment particularly in the last 8 years (2010-2018); however, the enrollment rate for adolescent and young adults was not substantially different than enrollment of children. The reasons for reduced enrollments are most likely multifactorial and complex. It is imperative that we continue to develop novel clinical studies using a portfolio of federal, investigator-initiated, and industry trials for pediatric oncology patients to continue to advance outcomes, study survivorship, and improve quality of life for these patients.

The availability of Erwinia Asparaginase has been limited across the world due to manufacturing shortages or for some countries due to the high acquisition cost, putting patients at risk for inferior outcomes. This manuscript provides guidance on how to manage hypersensitivity reactions and utilize therapeutic drug monitoring (TDM) to conserve and limit Erwinia use. The clinical and financial impact of a multidisciplinary committee are also discussed. Faced with a global Erwinia shortage, a multidisciplinary asparaginase allergy committee was created to review all hypersensitivity reactions to asparaginase therapy, staff education was performed on the management of asparaginase hypersensitivity reactions, an institution-wide premedication policy was mandated, and standardized guidelines were created for TDM. This multidisciplinary approach reduced the PEG-asparaginase to Erwinia switch rate from 21% (35 of 163) to 7% (10 of 134) (

Familial adenomatous polyposis (FAP) is a cancer predisposition syndrome driven by germline loss-of-function of the APC gene and phenotypically manifests with intestinal polyposis and a variety of extra-intestinal bone and soft tissue tumors. Craniopharyngioma is not a well-described FAP-associated tumor, however, six cases have been reported in adults, all demonstrating ectopic location and adamantinomatous histology. We report the first case of craniopharyngioma associated with FAP in a pediatric patient. A seven-year-old girl who presented with headache and vomiting was found on magnetic resonance imaging to have a suprasellar mass with cystic extension to the pre-pontine space. The tumor represented an adamantinomatous craniopharyngioma (aCP) with nuclear β-catenin expression. Whole exome sequencing confirmed a CTNNB1 activating point mutation and a germline APC frameshift variant. This case represents the first FAP-associated craniopharyngioma in childhood…. expanding our understanding of the molecular underpinnings driving tumorigenesis in this unique patient.

Neuroblastoma (NB) is the most common extracranial pediatric tumor, and accounts for approximately 12% of cancer-related deaths in children. Though several genomic drivers have been identified, the development of targeted therapy for treating this aggressive pediatric malignancy has yet to be realized. Thus, there exists an urgent need to develop alternative therapeutic strategies for treating aggressive and metastatic NB. One novel approach is to therapeutically target anaplastic lymphoma kinase (ALK) and focal adhesion kinase (FAK), which are multi-functional tyrosine kinases implicated in neural development and play an important role in growth and metastasis of several cancers. Genomic aberrations of ALK such as overexpression, amplifications, and mutations, have been reported in NB. The role of FAK has also been delineated in NB as well as associated with disease metastasis. Using in silico analysis of sequencing data from NB patients procured from Pediatric MI-ONCOSEQ (precision oncology program), we found a cohort of patients that express high ALK and FAK expression. Given the potential roles of ALK and FAK in NB, we evaluated the efficacy of a novel compound ESK440, which is a dual ALK and FAK inhibitor. ESK440 has passed Phase 1 clinical trials in adult patients with solid tumors. It is capable of crossing the blood brain barrier and binds to several mutated forms of ALK, thus making ESK440 an attractive therapeutic candidate for treating NB. A wide panel of NB cancer cell lines were screened with ESK440, and a CellTiter-Glo® Luminescent Cell Viability Assay was used to determine the IC-50s. Our results revealed that NB cells with ALK genomic aberrations (mutations and amplifications) showed low IC-50 values. Further, treatment with ESK440 inhibited ALK and FAK associated signaling pathways. We also observed decreased expression of MYCN. Intriguingly, ESK440 studies in NB xenograft model (NB-1) resulted in tumor regression in treated animals. Altogether, our study has discovered the therapeutic potential of dual ALK and FAK inhibitor in NB, and our findings may provide the foundation for initiating clinical trials targeting this disease in pediatric patients. Citation Format: Seema Chugh, Jean C. Tien, Jennifer Hon, Pushpinder Singh Bawa, Carson Kenum, Chi Chiang Li, Yunhui Cheng, Andrew D. Delekta, Jae Eun Choi, Rahul Mannan, Yuanyuan Qiao, Rajen Mody, Arul Chinnaiyan. Therapeutic benefit of dual ALK and FAK inhibition in neuroblastoma [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 2018.

10025 Background: Encouraging responses to chemoimmunotherapy with I/T/DIN/GM-CSF have been observed in trials for patients (pts) with relapsed/refractory HR-NBL, but factors associated with response have not been identified and duration of response has not been assessed. We aimed to evaluate timing and duration of response among pts with relapsed HR-NBL treated with I/T/DIN/GM-CSF and identify factors associated with response. Methods: We performed a multicenter retrospective cohort study of pts treated with I/T/DIN/GM-CSF. Eligibility criteria included: diagnosis of relapsed HR-NBL prior to age 30; objective response [OR; complete, partial, or minor response (CR, PR, or MR) by International Neuroblastoma Response Criteria (INRC)] or stable disease (SD) after initial therapy; receipt of I/T/DIN/GM-CSF for relapse or progression outside a clinical trial from 1/1/15-6/1/20. Logistic regression was used to identify factors associated with OR. Kaplan Meier analysis was used to determine progression-free survival (PFS). Results: We enrolled 143 pts with a median age at diagnosis of 51 months. Tumors were MYCN amplified in 52 (36%) and ALK was wild type in 73/94 (78% of tumors in which ALK status was known). 79 (55%) had received prior anti-GD2 therapy. I/T/DIN/GM-CSF comprised first relapse therapy in 96 pts (67%), second relapse therapy in 23 (16%) and subsequent therapy in 24 (17%). 70 (49%) achieved OR following I/T/DIN/GM-CSF therapy [29% CR, 15% PR, 5% MR], 30 (21%) achieved SD and 43 (30%) progressed. Median cycles received was 5 (range 1-31). 121 patients (85%) had their best response upon first disease evaluation. Later disease evaluations showed improved INRC classification in 14% of pts with initial SD, 33% with MR, and 41% with PR. Median time to OR was 2 months (range 1-21). Of the 105 relapse/progression events after starting I/T/DIN/GM-CSF (73% of pts), 59 (56%) occurred during therapy. Of the 42 pts who achieved CR with I/T/DIN/GM-CSF, 5 (12%) relapsed during I/T/DIN/GM-CSF and 17 (40%) relapsed after discontinuation. I/T/DIN/GM-CSF was discontinued in 83 pts (58%) due to suboptimal response or PD, and in 19 (13%) for toxicity. Median PFS among objective responders was 15.5 months. Among those in CR, median PFS after discontinuation of I/T/DIN/GM-CSF was 11.8 months (range 0.7-70.6). Multivariable models did not identify clinical or biologic factors associated with OR. Conclusions: 49% of pts receiving I/T/DIN/GM-CSF for relapsed HR-NBL achieved OR. Among responders, median response duration was 15.5 months. Pts with SD on first disease evaluation were unlikely to achieve OR, but > 1/3 of pts with MR/PR on first evaluation ultimately achieved CR. No identifiable clinical or biologic factors were associated with OR.

10041 Background: Lorlatinib, a macrocyclic ATP-competitive ALK inhibitor, exerts potent activity against neuroblastoma (NB) xenograftsharboring the most common ALK mutations. We performed a first-in-child phase 1 study of lorlatinib for patients with refractory/relapsed (R/R) ALK aberrant high-risk NB. We previously reported on Part A of the study, where safety of single agent lorlatinib was determined, showing complete responses (CR) to lorlatinib at the recommended phase 2 dose (RP2D) of 115 mg/m2 in pts < 18 years and 150 mg in pts > 18 yrs. Part B of the study aimed to determine the safety, pharmacokinetics (PK), RP2D, and explore the anti-tumor activity of lorlatinib in combination with topotecan and cyclophosphamide in pts with R/R ALK-driven NB. Methods: Patients with R/R NB ages 1-17 years with ALK mutations or amplification were eligible; prior ALK inhibitor (ALKi) treatment was allowed. Lorlatinib was orally administered once daily on days 1-28 with topotecan (0.75 mg/m2/day) and cyclophosphamide (250 mg/m2/day) administered intravenously days 1-5 and GCSF starting day 6. Two lorlatinib dose levels (DL) of 95 mg/m2/day (DL4B) and 115 mg/m2/day (DL5B) were assessed using a 3+3 dose escalation design with the primary endpoint of dose limiting toxicity (DLT) in Course 1. We report lorlatinib safety, PK, and objective response rate (ORR) for patients enrolled on Part B. Results: Between 10FEB2020 and 03DEC2021,9 eligible pts enrolled on Part B with a median age of 6.7 years (3.7-12.7). Three pts were enrolled onto DL4B and six onto DL5B (2/3 pts on DL4B and 4/6 pts on DL5B had received prior ALKi therapy) with no DLT’s observed in course 1. One patient on DL5B experienced a neuropsychological DLT in Course 3. Most common treatment-related adverse events were hematological, febrile neutropenia, high cholesterol, hypertriglyceridemia, and neuropsychological effects. The median number of courses received was 6 with a range of 1-8 on DL4B and 1-7 on DL5B. Of the 8 patients evaluable for response, ORR was 50%: 2/3 pts on DL4B and 2/5 pts on DL5B. Preliminary PK data demonstrate comparable dose level-associated lorlatinib steady state exposure between Part B chemotherapy combination and Part A monotherapy cohorts, supporting that chemotherapy had no effect on lorlatinib exposure that there are no overlapping toxicities. Conclusions: Lorlatinib in combination with topotecan and cyclophosphamide is well tolerated, and early data suggest encouraging objective anti-tumor activity. These data support the current integration of lorlatinib into up-front high risk neuroblastoma therapy for patients with ALK-driven neuroblastoma. Clinical trial information: NCT03107988.

e22015 Background: GSK-3β overexpression is associated with aggressive malignancies, treatment resistance and poor prognosis. The GSK-3β inhibitor Elraglusib induces apoptosis via NFΚB and p53 pathways and has potent anti-fibrotic and immunomodulatory activity. Adult studies of elraglusib demonstrate clinical activity in pancreatic cancer, melanoma, lymphoma and sarcoma as a single agent or in combination with cytotoxic chemotherapy. Elraglusib is active in in vivo models of neuroblastoma (NBL) and malignant glioma. This first-in-pediatrics study (NCT04239092) is evaluating the safety, pharmacokinetics (PK), and efficacy of elraglusib monotherapy and in combination with chemotherapy in patients with refractory malignancies. Methods: Elraglusib is given intravenously (IV) twice-weekly at 3 dose levels (DL) (9.3, 12.4 and 15 mg/kg) as a single agent or in combination with irinotecan, cyclophosphamide/topotecan or temozolomide/irinotecan in 21-day cycles. A cohort of pts with refractory NBL will be treated at the recommended phase 2 dose (RP2D) of elraglusib with temozolomide/irinotecan. Results: As of January 2022, 23 pts (n = 7 female, median age 14.2 years) have received at least one dose of elraglusib. Tumor types: 5 NBL, 3 diffuse midline glioma (DMG), 3 osteosarcoma (OS), 3 ependymoma (EP), 2 alveolar rhabdomyosarcoma (aRMS), 1 angiosarcoma (AS), 1 Ewing sarcoma (ES), 1 glioblastoma (GBM), 1 hepatoblastoma (HB), 1 embryonal CNS tumor NOS, 1 NUT midline carcinoma, 1 pineoblastoma (PB). Median time from diagnosis is 26 months (range: 6.7 – 156.3) and median number of lines of prior systemic therapy is 2 (range 0-14). Two DLs of single agent (6 pts) have been completed (9.3 and 12.4 mg/kg) without elraglusib-attributable severe adverse events (SAEs). Of the 15 patients on the combination arm with irinotecan or cyclophosphamide/topotecan, a single adverse event (Grade 4 hypotension/infusion reaction) was reported. Grade 1/2 elraglusib attributable-AEs include: transient visual change (n = 10), nausea (n = 7), vomiting (n = 6), fatigue (n = 2), hypotension (n = 2) and infusion reaction (n = 1). One pt with recurrent ES had a radiographic and pathologic CR after 3 cycles of elraglusib/cyclophosphamide/topotecan. 6 pts (26.1%) had SD (2 NBL, 1 aRMS, 1 EP, 1 OS, 1 GBM). 8 pts (35%) remained on study treatment ≥ 3 months (2 NBL, 2 EP, 1 OS, 1 aRMS, 1 ES, 1 PB). Median treatment duration was 40 days (range 1 - 126). 4 pts remain on therapy. Conclusions: Elraglusib is well tolerated as a single agent and with several chemotherapy regimens in this heavily pretreated pediatric population with refractory cancers. It has encouraging antitumor activity, with 1 CR in a patient with recurrent ES. Enrollment is ongoing; a RPD2 has not been reached. Clinical trial information: NCT04239092.