Histone H3.3G34-Mutant Interneuron Progenitors Co-opt PDGFRA for Gliomagenesis.

Histone H3.3 glycine 34 to arginine/valine (G34R/V) mutations drive deadly gliomas and show exquisite regional and temporal specificity, suggesting a developmental context permissive to their effects. Here we show that 50% of G34R/V tumors (n = 95) bear activating PDGFRA mutations that display strong selection pressure at recurrence. Although considered gliomas, G34R/V tumors actually arise in GSX2/DLX-expressing interneuron progenitors, where G34R/V mutations impair neuronal differentiation. The lineage of origin may facilitate PDGFRA co-option through a chromatin loop connecting PDGFRA to GSX2 regulatory elements, promoting PDGFRA overexpression and mutation. At the single-cell level, G34R/V tumors harbor dual neuronal/astroglial identity and lack oligodendroglial programs, actively repressed by GSX2/DLX-mediated cell fate specification. G34R/V may become dispensable for tumor maintenance, whereas mutant-PDGFRA is potently oncogenic. Collectively, our results open novel research avenues in deadly tumors. G34R/V gliomas are neuronal malignancies where interneuron progenitors are stalled in differentiation by G34R/V mutations and malignant gliogenesis is promoted by co-option of a potentially targetable pathway, PDGFRA signaling.

Comprehensive Analysis of Hypermutation in Human Cancer.

We present an extensive assessment of mutation burden through sequencing analysis of >81,000 tumors from pediatric and adult patients, including tumors with hypermutation caused by chemotherapy, carcinogens, or germline alterations. Hypermutation was detected in tumor types not previously associated with high mutation burden. Replication repair deficiency was a major contributing factor. We uncovered new driver mutations in the replication-repair-associated DNA polymerases and a distinct impact of microsatellite instability and replication repair deficiency on the scale of mutation load. Unbiased clustering, based on mutational context, revealed clinically relevant subgroups regardless of the tumors' tissue of origin, highlighting similarities in evolutionary dynamics leading to hypermutation. Mutagens, such as UV light, were implicated in unexpected cancers, including sarcomas and lung tumors. The order of mutational signatures identified previous treatment and germline replication repair deficiency, which improved management of patients and families. These data will inform tumor classification, genetic testing, and clinical trial design.

Clinical and biological landscape of constitutional mismatch-repair deficiency syndrome: an International Replication Repair Deficiency Consortium cohort study.

BACKGROUND: Constitutional mismatch repair deficiency (CMMRD) syndrome is a rare and aggressive cancer predisposition syndrome. Because a scarcity of data on this condition contributes to management challenges and poor outcomes, we aimed to describe the clinical spectrum, cancer biology, and impact of genetics on patient survival in CMMRD. METHODS: In this cohort study, we collected cross-sectional and longitudinal data on all patients with CMMRD, with no age limits, registered with the International Replication Repair Deficiency Consortium (IRRDC) across more than 50 countries. Clinical data were extracted from the IRRDC database, medical records, and physician-completed case record forms. The primary objective was to describe the clinical features, cancer spectrum, and biology of the condition. Secondary objectives included estimations of cancer incidence and of the impact of the specific mismatch-repair gene and genotype on cancer onset and survival, including after cancer surveillance and immunotherapy interventions. FINDINGS: We analysed data from 201 patients (103 males, 98 females) enrolled between June 5, 2007 and Sept 9, 2022. Median age at diagnosis of CMMRD or a related cancer was 8·9 years (IQR 5·9-12·6), and median follow-up from diagnosis was 7·2 years (3·6-14·8). Endogamy among minorities and closed communities contributed to high homozygosity within countries with low consanguinity. Frequent dermatological manifestations (117 [93%] of 126 patients with complete data) led to a clinical overlap with neurofibromatosis type 1 (35 [28%] of 126). 339 cancers were reported in 194 (97%) of 201 patients. The cumulative cancer incidence by age 18 years was 90% (95% CI 80-99). Median time between cancer diagnoses for patients with more than one cancer was 1·9 years (IQR 0·8-3·9). Neoplasms developed in 15 organs and included early-onset adult cancers. CNS tumours were the most frequent (173 [51%] cancers), followed by gastrointestinal (75 [22%]), haematological (61 [18%]), and other cancer types (30 [9%]). Patients with CNS tumours had the poorest overall survival rates (39% [95% CI 30-52] at 10 years from diagnosis; log-rank p<0·0001 across four cancer types), followed by those with haematological cancers (67% [55-82]), gastrointestinal cancers (89% [81-97]), and other solid tumours (96% [88-100]). All cancers showed high mutation and microsatellite indel burdens, and pathognomonic mutational signatures. MLH1 or MSH2 variants caused earlier cancer onset than PMS2 or MSH6 variants, and inferior survival (overall survival at age 15 years 63% [95% CI 55-73] for PMS2, 49% [35-68] for MSH6, 19% [6-66] for MLH1, and 0% for MSH2; p<0·0001). Frameshift or truncating variants within the same gene caused earlier cancers and inferior outcomes compared with missense variants (p<0·0001). The greater deleterious effects of MLH1 and MSH2 variants as compared with PMS2 and MSH6 variants persisted despite overall improvements in survival after surveillance or immune checkpoint inhibitor interventions. INTERPRETATION: The very high cancer burden and unique genomic landscape of CMMRD highlight the benefit of comprehensive assays in timely diagnosis and precision approaches toward surveillance and immunotherapy. These data will guide the clinical management of children and patients who survive into adulthood with CMMRD. FUNDING: The Canadian Institutes for Health Research, Stand Up to Cancer, Children's Oncology Group National Cancer Institute Community Oncology Research Program, Canadian Cancer Society, Brain Canada, The V Foundation for Cancer Research, BioCanRx, Harry and Agnieszka Hall, Meagan's Walk, BRAINchild Canada, The LivWise Foundation, St Baldrick Foundation, Hold'em for Life, and Garron Family Cancer Center.

Phase 1 study of high-dose DFMO, celecoxib, cyclophosphamide and topotecan for patients with relapsed neuroblastoma: a New Approaches to Neuroblastoma Therapy trial.

BACKGROUND: MYC genes regulate ornithine decarboxylase (Odc) to increase intratumoral polyamines. We conducted a Phase I trial [NCT02030964] to determine the maximum tolerated dose (MTD) of DFMO, an Odc inhibitor, with celecoxib, cyclophosphamide and topotecan. METHODS: Patients 2-30 years of age with relapsed/refractory high-risk neuroblastoma received oral DFMO at doses up to 9000 mg/m2/day, with celecoxib (500 mg/m2 daily), cyclophosphamide (250 mg/m2/day) and topotecan (0.75 mg/m2/day) IV for 5 days, for up to one year with G-CSF support. RESULTS: Twenty-four patients (median age, 6.8 years) received 136 courses. Slow platelet recovery with 21-day courses (dose-levels 1 and 2) led to subsequent dose-levels using 28-day courses (dose-levels 2a-4a). There were three course-1 dose-limiting toxicities (DLTs; hematologic; anorexia; transaminases), and 23 serious adverse events (78% fever-related). Five patients (21%) completed 1-year of therapy. Nine stopped for PD, 2 for DLT, 8 by choice. Best overall response included two PR and four MR. Median time-to-progression was 19.8 months, and 3 patients remained progression-free at >4 years without receiving additional therapy. The MTD of DFMO with this regimen was 6750 mg/m2/day. CONCLUSION: High-dose DFMO is tolerable when added to chemotherapy in heavily pre-treated patients. A randomized Phase 2 trial of DFMO added to chemoimmunotherapy is ongoing [NCT03794349].

LOGGIC/FIREFLY-2: a phase 3, randomized trial of tovorafenib vs. chemotherapy in pediatric and young adult patients with newly diagnosed low-grade glioma harboring an activating RAF alteration.

BACKGROUND: Pediatric low-grade glioma (pLGG) is essentially a single pathway disease, with most tumors driven by genomic alterations affecting the mitogen-activated protein kinase/ERK (MAPK) pathway, predominantly KIAA1549::BRAF fusions and BRAF V600E mutations. This makes pLGG an ideal candidate for MAPK pathway-targeted treatments. The type I BRAF inhibitor, dabrafenib, in combination with the MEK inhibitor, trametinib, has been approved by the United States Food and Drug Administration for the systemic treatment of BRAF V600E-mutated pLGG. However, this combination is not approved for the treatment of patients with tumors harboring BRAF fusions as type I RAF inhibitors are ineffective in this setting and may paradoxically enhance tumor growth. The type II RAF inhibitor, tovorafenib (formerly DAY101, TAK-580, MLN2480), has shown promising activity and good tolerability in patients with BRAF-altered pLGG in the phase 2 FIREFLY-1 study, with an objective response rate (ORR) per Response Assessment in Neuro-Oncology high-grade glioma (RANO-HGG) criteria of 67%. Tumor response was independent of histologic subtype, BRAF alteration type (fusion vs. mutation), number of prior lines of therapy, and prior MAPK-pathway inhibitor use. METHODS: LOGGIC/FIREFLY-2 is a two-arm, randomized, open-label, multicenter, global, phase 3 trial to evaluate the efficacy, safety, and tolerability of tovorafenib monotherapy vs. current standard of care (SoC) chemotherapy in patients < 25 years of age with pLGG harboring an activating RAF alteration who require first-line systemic therapy. Patients are randomized 1:1 to either tovorafenib, administered once weekly at 420 mg/m2 (not to exceed 600 mg), or investigator's choice of prespecified SoC chemotherapy regimens. The primary objective is to compare ORR between the two treatment arms, as assessed by independent review per RANO-LGG criteria. Secondary objectives include comparisons of progression-free survival, duration of response, safety, neurologic function, and clinical benefit rate. DISCUSSION: The promising tovorafenib activity data, CNS-penetration properties, strong scientific rationale combined with the manageable tolerability and safety profile seen in patients with pLGG led to the SIOPe-BTG-LGG working group to nominate tovorafenib for comparison with SoC chemotherapy in this first-line phase 3 trial. The efficacy, safety, and functional response data generated from the trial may define a new SoC treatment for newly diagnosed pLGG. TRIAL REGISTRATION: ClinicalTrials.gov: NCT05566795. Registered on October 4, 2022.

Management of patients with diffuse intrinsic pontine glioma in Australia and New Zealand: Australian and New Zealand Children's Haematology/Oncology Group position statement.

INTRODUCTION: The main mission of the Australian and New Zealand Children's Haematology and Oncology Group (ANZCHOG) is to develop and facilitate local access to the world's leading evidence-based clinical trials for all paediatric cancers, including brain tumours, as soon as practically possible. Diffuse intrinsic pontine gliomas (DIPGs) - a subset of a larger group of tumours now termed diffuse midline glioma, H3K27-altered (DMG) - are paediatric brain cancers with less than 10% survival at two years. In the absence of any proven curative therapies, significant recent advancements have been made in pre-clinical and clinical research, leading many to seek integration of novel therapies early into standard practice. Despite these innovative therapeutic approaches, DIPG remains an incurable disease for which novel surgical, imaging, diagnostic, radiation and systemic therapy approaches are needed. MAIN RECOMMENDATIONS: All patients with DIPG should be discussed in multidisciplinary neuro-oncology meetings (including pathologists, neuroradiologists, radiation oncologists, neurosurgeons, medical oncologists) at diagnosis and at relapse or progression. Radiation therapy to the involved field remains the local and international standard of care treatment. Proton therapy does not yield a superior survival outcome compared with photon therapy and patients should undergo radiation therapy with the available modality (photon or proton) at their treatment centre. Patients may receive concurrent chemotherapy or radiation-sensitising agents as part of a clinical trial. Biopsy should be offered to facilitate consideration of experimental therapies and eligibility for clinical trial participation. After radiation therapy, each patient should be managed individually with either observation or considered for enrolment on a clinical trial, if eligible, after full discussion with the family. Re-irradiation can be considered for progressive disease. CHANGES IN MANAGEMENT AS A RESULT OF THE GUIDELINE: Every child diagnosed with DIPG should be offered enrolment on a clinical trial where available. Access to investigational drugs without biological rationale outside the clinical trial setting is not supported. In case of potentially actionable target identification with molecular profiling and absence of a suitable clinical trial, rational targeted therapies can be considered through compassionate access programs.

Communicating with families of young people with hard-to-treat cancers: Healthcare professionals' perspectives on challenges, skills, and training.

OBJECTIVES: Hard-to-treat childhood cancers are those where standard treatment options do not exist and the prognosis is poor. Healthcare professionals (HCPs) are responsible for communicating with families about prognosis and complex experimental treatments. We aimed to identify HCPs' key challenges and skills required when communicating with families about hard-to-treat cancers and their perceptions of communication-related training. METHODS: We interviewed Australian HCPs who had direct responsibilities in managing children/adolescents with hard-to-treat cancer within the past 24 months. Interviews were analyzed using qualitative content analysis. RESULTS: We interviewed 10 oncologists, 7 nurses, and 3 social workers. HCPs identified several challenges for communication with families including: balancing information provision while maintaining realistic hope; managing their own uncertainty; and nurses and social workers being underutilized during conversations with families, despite widespread preferences for multidisciplinary teamwork. HCPs perceived that making themselves available to families, empowering them to ask questions, and repeating information helped to establish and maintain trusting relationships with families. Half the HCPs reported receiving no formal training for communicating prognosis and treatment options with families of children with hard-to-treat cancers. Nurses, social workers, and less experienced oncologists supported the development of communication training resources, more so than more experienced oncologists. SIGNIFICANCE OF RESULTS: Resources are needed which support HCPs to communicate with families of children with hard-to-treat cancers. Such resources may be particularly beneficial for junior oncologists and other HCPs during their training, and they should aim to prepare them for common challenges and foster greater multidisciplinary collaboration.

Parents' and adolescents' perspectives and understanding of information about childhood cancer precision medicine.

BACKGROUND: Precision medicine is projected to become integral to childhood cancer care. As such, it is essential to support families to understand what precision medicine entails. METHODS: A total of 182 parents and 23 adolescent patients participating in Precision Medicine for Children with Cancer (PRISM), an Australian precision medicine clinical trial for high-risk childhood cancer, completed questionnaires after study enrollment (time 0 [T0]). Of the parents, 108 completed a questionnaire and 45 completed an interview following return of precision medicine results (time 1 [T1]). We analyzed the mixed-methods data comprising measures exploring families' perceptions and understanding of PRISM's participant information sheet and consent form (PISCF), and factors associated with understanding. RESULTS: Most parents were satisfied with the PISCF, rating it as at least "somewhat" clearly presented (n = 160/175; 91%) and informative (n = 158/175; 90%). Many suggested improvements including the use of clearer language and a more visually engaging format. Parents' actual understanding of precision medicine was low on average, but scores improved between T0 and T1 (55.8/100-60.0/100; p = .012). Parents from culturally and/or linguistically diverse backgrounds (n = 42/177; 25%) had lower actual understanding scores than those from a Western/European background whose first language was English (p = .010). There was little correlation between parents' perceived and actual understanding scores (p = .794; Pearson correlation -0.020; 95% CI, -0.169 to 0.116). Most adolescent patients read the PISCF either "briefly" or "not at all" (70%) and had a perceived understanding score of 63.6/100 on average. CONCLUSIONS: Our study revealed gaps in families' understanding of childhood cancer precision medicine. We highlighted areas for potential intervention such as through targeted information resources. PLAIN LANGUAGE SUMMARY: Precision medicine is projected to become part of the standard of care for children with cancer. Precision medicine aims to give the right treatment to the right patient and involves several complex techniques, many of which may be challenging to understand. Our study analyzed questionnaire and interview data from parents and adolescent patients enrolled in an Australian precision medicine trial. Findings revealed gaps in families' understanding of childhood cancer precision medicine. Drawing on parents' suggestions and the literature, we make brief recommendations about improving information provision to families, such as through targeted information resources.

Parents' expectations, preferences, and recall of germline findings in a childhood cancer precision medicine trial.

BACKGROUND: Germline genome sequencing in childhood cancer precision medicine trials may reveal pathogenic or likely pathogenic variants in cancer predisposition genes in more than 10% of children. These findings can have implications for diagnosis, treatment, and the child's and family's future cancer risk. Understanding parents' perspectives of germline genome sequencing is critical to successful clinical implementation. METHODS: A total of 182 parents of 144 children (<18 years of age) with poor-prognosis cancers enrolled in the Precision Medicine for Children with Cancer trial completed a questionnaire at enrollment and after the return of their child's results, including clinically relevant germline findings (received by 13% of parents). Parents' expectations of germline genome sequencing, return of results preferences, and recall of results received were assessed. Forty-five parents (of 43 children) were interviewed in depth. RESULTS: At trial enrollment, most parents (63%) believed it was at least "somewhat likely" that their child would receive a clinically relevant germline finding. Almost all expressed a preference to receive a broad range of germline genomic findings, including variants of uncertain significance (88%). Some (29%) inaccurately recalled receiving a clinically relevant germline finding. Qualitatively, parents expressed confusion and uncertainty after the return of their child's genome sequencing results by their child's clinician. CONCLUSIONS: Many parents of children with poor-prognosis childhood cancer enrolled in a precision medicine trial expect their child may have an underlying cancer predisposition syndrome. They wish to receive a wide scope of information from germline genome sequencing but may feel confused by the reporting of trial results.

Larotrectinib efficacy and safety in adult patients with tropomyosin receptor kinase fusion sarcomas.

BACKGROUND: Larotrectinib, a first-in-class, highly selective tropomyosin receptor kinase (TRK) inhibitor, has demonstrated efficacy in adult and pediatric patients with various solid tumors harboring NTRK gene fusions. This subset analysis focuses on the efficacy and safety of larotrectinib in an expanded cohort of adult patients with TRK fusion sarcomas. METHODS: Patients (≥18 years old) with sarcomas harboring NTRK gene fusions were identified from three clinical trials. Patients received larotrectinib 100 mg orally twice daily. Response was investigator-assessed per RECIST v1.1. Data cutoff was July 20, 2021. RESULTS: At the data cutoff, 36 adult patients with TRK fusion sarcomas had initiated larotrectinib therapy: two (6%) patients had bone sarcomas, four (11%) had gastrointestinal stromal tumors, and 30 (83%) had soft tissue sarcomas. All patients were evaluable for response and demonstrated an objective response rate of 58% (95% confidence interval, 41-74). Patients responded well to larotrectinib regardless of number of prior lines of therapy. Adverse events (AEs) were mostly grade 1/2. Grade 3 treatment-emergent AEs (TEAEs) occurred in 15 (42%) patients. There were no grade 4 TEAEs. Two grade 5 TEAEs were reported, neither of which were considered related to larotrectinib. Four (11%) patients permanently discontinued treatment due to TEAEs. CONCLUSIONS: Larotrectinib demonstrated robust and durable responses, extended survival benefit, and a favorable safety profile in adult patients with TRK fusion sarcomas with longer follow-up. These results continue to demonstrate that testing for NTRK gene fusions should be incorporated into the clinical management of adult patients with various types of sarcomas. PLAIN LANGUAGE SUMMARY: Tropomyosin receptor kinase (TRK) fusion proteins result from translocations involving the NTRK gene and cause cancer in a range of tumor types. Larotrectinib is an agent that specifically targets TRK fusion proteins and is approved for the treatment of patients with TRK fusion cancer. This study looked at how well larotrectinib worked in adult patients with sarcomas caused by TRK fusion proteins. Over half of patients had a durable response to larotrectinib, with no unexpected side effects. These results show that larotrectinib is safe and effective in adult patients with TRK fusion sarcomas.

Hopes, concerns, satisfaction and regret in a precision medicine trial for childhood cancer: a mixed-methods study of parent and patient perspectives.

BACKGROUND: Paediatric precision oncology aims to match therapeutic agents to driver gene targets. We investigated whether parents and patients regret participation in precision medicine trials, particularly when their hopes are unfulfilled. METHODS: Parents and adolescent patients completed questionnaires at trial enrolment (T0) and after receiving results (T1). Parents opted-in to an interview at T1. Bereaved parents completed a questionnaire 6-months post-bereavement (T1B). We analysed quantitative data with R and qualitative data thematically with NVivo, before integrating all data for interpretation. RESULTS: 182 parents and 23 patients completed T0; 108/182 parents and 8/23 patients completed T1; 27/98 bereaved parents completed T1B; and 45/108 parents were interviewed. At enrolment, participants held concurrent hopes that precision medicine would benefit future children and their child. Participants expressed concern regarding wait-times for receipt of results. Most participants found the trial beneficial and not burdensome, including bereaved parents. Participants reported high trial satisfaction (median scores: parents: 93/100; patients: 80/100). Participants expressed few regrets (parent median scores: parents: 10/100; bereaved parents: 15/100; patient regret: 2/8 expressed minimal regret). CONCLUSIONS: Even when trial outcomes did not match their hopes, parents and patients rarely regretted participating in a childhood cancer precision medicine trial. These data are critical for integrating participants' views into future precision medicine delivery.

Decitabine and vorinostat with FLAG chemotherapy in pediatric relapsed/refractory AML: Report from the therapeutic advances in childhood leukemia and lymphoma (TACL) consortium.

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 (<0.1%) by centralized flow cytometry and 84% (n = 16) successfully proceeded to hematopoietic stem cell transplant. Two-year overall survival was 75.6% [95%CI: 47.3%, 90.1%] for MRD-negative patients vs. 17.9% [95%CI: 4.4%, 38.8%] for those with residual disease (p < .001). Twelve subjects (34%) had known epigenetic alterations with 8 (67%) achieving a CR, 7 (88%) of whom were MRD negative. Correlative pharmacodynamics demonstrated the biologic activity of decitabine and vorinostat and identified specific gene enrichment signatures in nonresponding patients. Overall, this therapy was well-tolerated, biologically active, and effective in pediatric patients with R/R AML, particularly those with epigenetic alterations.

Phase 1b study of carfilzomib with induction chemotherapy in pediatric relapsed/refractory acute lymphoblastic leukemia.

BACKGROUND: Acute lymphoblastic leukemia (ALL) is the most common cancer diagnosed in childhood. Survival for patients following relapse remains poor, and achieving complete remission (CR) after relapse is the first critical step to cure. Carfilzomib is a proteasome inhibitor with an acceptable safety profile and clinical activity in adults with multiple myeloma but has not been assessed in children. The primary objective of this phase 1b study was to assess the safety and tolerability of carfilzomib combined with vincristine, dexamethasone, asparaginase, and daunorubicin (VXLD) in children with relapsed and/or refractory ALL. METHODS: Patients aged 1-21 years (n = 24) received 4-week induction therapy with carfilzomib at dose levels of 27 mg/m2 (n = 3), 36 mg/m2 (n = 7), 45 mg/m2 (n = 4), and 56 mg/m2 (n = 10) in combination with VXLD. Patients achieving stable disease were offered further consolidation chemotherapy. Analyses were based on the safety evaluable population. RESULTS: Following dose escalation of carfilzomib, the recommended phase 2 carfilzomib dose was identified as 56 mg/m2 . Grade ≥3 hematological adverse events were common (83%, 20/24 patients), and serious treatment-emergent adverse events occurred in 58% (14/24) of patients. At the end of induction, CR/CR with incomplete platelet recovery (CRp)/CR with incomplete blood count recovery (CRi) was identified in 50% of patients (n = 12/24). By the end of consolidation, cumulative CR/CRp/CRi was identified in 58% of patients (n = 14/24). CONCLUSION: These data support the use of carfilzomib in pediatric patients with relapsed and/or refractory ALL.

Nelarabine, etoposide, and cyclophosphamide in relapsed pediatric T-acute lymphoblastic leukemia and T-lymphoblastic lymphoma (study T2008-002 NECTAR).

Children with relapse of T-cell acute lymphoblastic leukemia (T-ALL) or lymphoblastic lymphoma (T-LBL) have a dismal prognosis, largely due to difficulty attaining second remission. We hypothesized that adding etoposide and cyclophosphamide to the nucleoside analog nelarabine could improve response rates over single-agent nelarabine for relapsed T-ALL and T-LBL. This phase I dose-escalation trial's primary objective was to evaluate the dose and safety of nelarabine given in combination with etoposide at 100 mg/m2 /day and cyclophosphamide at 330-400 mg/m2 /day, each for 5 consecutive days in children with either T-ALL (13 patients) or T-LBL (10 patients). Twenty-three patients were treated at three dose levels; 21 were evaluable for dose-limiting toxicities (DLT) and response. The recommended phase II doses (RP2D) for this regimen, when given daily ×5 every 3 weeks, were nelarabine 650 mg/m2 /day, etoposide 100 mg/m2 /day, and cyclophosphamide 400 mg/m2 /day. DLTs included peripheral motor and sensory neuropathies. An expansion cohort to evaluate responses at the RP2D was terminated early due to slow accrual. The overall best response rate was 38% (8/21), with 33% (4/12) responses in the T-ALL cohort and 44% (4/9) responses in the T-LBL cohort. These response rates are comparable to those seen with single-agent nelarabine in this setting. These data suggest that the addition of cyclophosphamide and etoposide to nelarabine does not increase the incidence of neurologic toxicities or the response rate beyond that obtained with single-agent nelarabine in children with first relapse of T-ALL and T-LBL.

Ceritinib in paediatric patients with anaplastic lymphoma kinase-positive malignancies: an open-label, multicentre, phase 1, dose-escalation and dose-expansion study.

BACKGROUND: Several paediatric malignancies, including anaplastic large cell lymphoma (ALCL), inflammatory myofibroblastic tumour (IMT), neuroblastoma, and rhabdomyosarcoma, harbour activation of anaplastic lymphoma kinase (ALK) through different mechanisms. Here, we report the safety, pharmacokinetics, and efficacy of ceritinib in paediatric patients with ALK-positive malignancies. METHODS: This multicentre, open-label, phase 1 trial was done at 23 academic hospitals in ten countries. Children (aged ≥12 months to <18 years) diagnosed with locally advanced or metastatic ALK-positive malignancies that had progressed despite standard therapy, or for which no effective standard therapy were available, were eligible. ALK-positive malignancies were defined as those with ALK rearrangement, amplification, point mutation, or in the case of rhabdomyosarcoma, expression in the absence of any genetic alteration. Eligible patients had evaluable or measurable disease as defined by either Response Evaluation Criteria in Solid Tumours, version 1.1 for patients with non-haematological malignancies, International Neuroblastoma Response Criteria scan for patients with neuroblastoma, or International Working Group criteria for patients with lymphoma. Other eligibility criteria were Karnofsky performance status score of at least 60% for patients older than 12 years or Lansky score of at least 50% for patients aged 12 years or younger. This study included a dose-escalation part, followed by a dose-expansion part, in which all patients received treatment at the recommended dose for expansion (RDE) established in the dose-escalation part. Both parts of the study were done in fasted and fed states. In the dose-escalation part, patients were treated with once-daily ceritinib orally, with dose adjusted for body-surface area, rounded to the nearest multiple of the 50 mg dose strength. The starting dose in the fasted state was 300 mg/m2 daily and for the fed state was 320 mg/m2 daily. The primary objective of this study was to establish the maximum tolerated dose (ie, RDE) of ceritinib in the fasted and fed states. The RDE was established on the basis of the incidence of dose-limiting toxicities in patients who completed a minimum of 21 days of treatment with safety assessments and at least 75% drug exposure, or who discontinued treatment earlier because of dose-limiting toxicity. Overall response rate (defined as the proportion of patients with a best overall response of complete response or partial response) was a secondary endpoint. Activity and safety analyses were done in all patients who received at least one dose of ceritinib. This trial is registered with ClinicalTrials.gov (NCT01742286) and is completed. FINDINGS: Between Aug 28, 2013, and Oct 17, 2017, 83 children with ALK-positive malignancies were enrolled to the dose-escalation (n=40) and dose-expansion (n=43) groups. The RDE of ceritinib was established as 510 mg/m2 (fasted) and 500 mg/m2 (fed). 55 patients (30 with neuroblastoma, ten with IMT, eight with ALCL, and seven with other tumour types) were treated with ceritinib at the RDE (13 patients at 510 mg/m2 fasted and 42 patients at 500 mg/m2 fed). The median follow-up was 33·3 months (IQR 24·8-39·3) for patients with neuroblastoma, 33·2 months (27·9-35·9) for those with IMT, 34·0 months (21·9-46·4) for those with ALCL, and 27·5 months (22·4-36·9) for patients with other tumour types. An overall response was recorded in six (20%; 95% CI 8-39) of 30 patients with neuroblastoma, seven (70%; 33-93) of ten patients with IMT, six (75%; 35-97) of eight patients with ALCL, and one (14%; <1-58) of seven patients with other tumours. The safety profile of ceritinib was consistent with that observed in adult patients. All patients had at least one adverse event. Grade 3 or 4 adverse events occurred in 67 (81%) of 83 patients and were mostly increases in aminotransferases (alanine aminotransferase increase in 38 [46%] patients and aspartate aminotransferase increase in 27 [33%] patients). At least one serious adverse event was reported in 40 (48%) of 83 patients and 31 (37%) of 83 patients had at least one grade 3 or 4 serious adverse event. 14 (17%) deaths occurred during the study, of which 12 were on-treatment deaths and two were after 30 days of the last dose. Of the 12 on-treatment deaths, ten were due to disease progression (neuroblastoma), one due to sepsis, and one due to intractable hypotension. INTERPRETATION: Ceritinib 500 mg/m2 once daily with food is the recommended dose for paediatric patients with ALK-positive malignancies. Ceritinib showed promising preliminary antitumour activity in patients with ALK-positive refractory or recurrent IMT or ALCL, and in a subset of patients with relapsed or refractory neuroblastoma, with a manageable safety profile. Our data support the notion that ALK inhibitors should be considered in therapeutic strategies for paediatric patients with malignancies with genetic ALK alterations. FUNDING: Novartis Pharmaceutical Corporation.

Gastrointestinal Hemorrhage: A Manifestation of the Telomere Biology Disorders.

OBJECTIVE: To describe the clinical features, therapeutic interventions, and patient outcomes of gastrointestinal (GI) hemorrhage in individuals with a telomere biology disorder, including dyskeratosis congenita, Hoyeraal-Hreidarsson syndrome, Revesz syndrome, and Coats plus. STUDY DESIGN: Clinical Care Consortium for Telomere Associated Ailments members were invited to contribute data on individuals with telomere biology disorders at their institutions who experienced GI bleeding. Patient demographic, laboratory, imaging, procedural, and treatment information and outcomes were extracted from the medical record. RESULTS: Sixteen patients who experienced GI hemorrhage were identified at 11 centers. Among 14 patients who underwent genetic testing, 8 had mutations in TINF2, 4 had mutations in CTC1 or STN1, and 1 patient each had a mutation in TERC and RTEL1. Ten patients had a history of hematopoietic cell transplantation. The patients with Coats plus and those without Coats plus had similar clinical features and courses. Angiodysplasia of the stomach and/or small bowel was described in 8 of the 12 patients who underwent endoscopy; only 4 had esophageal varices. Various medical interventions were trialed. No single intervention was uniformly associated with cessation of bleeding, although 1 patient had a sustained response to treatment with bevacizumab. Recurrence was common, and the overall long-term outcome for affected patients was poor. CONCLUSIONS: GI bleeding in patients with telomere biology disorders is associated with significant morbidity and with vascular ectasias rather than varices.

Germline-driven replication repair-deficient high-grade gliomas exhibit unique hypomethylation patterns.

Replication repair deficiency (RRD) leading to hypermutation is an important driving mechanism of high-grade glioma (HGG) occurring predominantly in the context of germline mutations in RRD-associated genes. Although HGG presents specific patterns of DNA methylation corresponding to oncogenic mutations, this has not been well studied in replication repair-deficient tumors. We analyzed 51 HGG arising in the background of gene mutations in RRD utilizing either 450 k or 850 k methylation arrays. These were compared with HGG not known to be from patients with RRD. RRD HGG harboring secondary mutations in glioma genes such as IDH1 and H3F3A displayed a methylation pattern corresponding to these methylation subgroups. Strikingly, RRD HGG lacking these known secondary mutations clustered together with an incompletely described group of HGG previously labeled "Wild type-C" or "Paediatric RTK 1". Independent analysis of two comparator HGG cohorts showed that other RRD/hypermutant tumors clustered within these subgroups, suggesting that undiagnosed RRD may be driving some HGG clustering in this location. RRD HGG displayed a unique CpG Island Demethylator Phenotype in contrast to the CpG Island Methylator Phenotype described in other cancers. Hypomethylation was enriched at gene promoters with prominent demethylation in genes and pathways critical to cellular survival including cell cycle, gene expression, cellular metabolism, and organization. These data suggest that methylation arrays may provide diagnostic information for the detection of RRD HGG. Furthermore, our findings highlight the unique natural selection pressures in these highly dysregulated, hypermutant cancers and provide the novel impact of hypermutation and RRD on the cancer epigenome.

Pineoblastoma segregates into molecular sub-groups with distinct clinico-pathologic features: a Rare Brain Tumor Consortium registry study.

Pineoblastomas (PBs) are rare, aggressive pediatric brain tumors of the pineal gland with modest overall survival despite intensive therapy. We sought to define the clinical and molecular spectra of PB to inform new treatment approaches for this orphan cancer. Tumor, blood, and clinical data from 91 patients with PB or supratentorial primitive neuroectodermal tumor (sPNETs/CNS-PNETs), and 2 pineal parenchymal tumors of intermediate differentiation (PPTIDs) were collected from 29 centres in the Rare Brain Tumor Consortium. We used global DNA methylation profiling to define a core group of PB from 72/93 cases, which were delineated into five molecular sub-groups. Copy number, whole exome and targeted sequencing, and miRNA expression analyses were used to evaluate the clinico-pathologic significance of each sub-group. Tumors designated as group 1 and 2 almost exclusively exhibited deleterious homozygous loss-of-function alterations in miRNA biogenesis genes (DICER1, DROSHA, and DGCR8) in 62 and 100% of group 1 and 2 tumors, respectively. Recurrent alterations of the oncogenic MYC-miR-17/92-RB1 pathway were observed in the RB and MYC sub-group, respectively, characterized by RB1 loss with gain of miR-17/92, and recurrent gain or amplification of MYC. PB sub-groups exhibited distinct clinical features: group 1-3 arose in older children (median ages 5.2-14.0 years) and had intermediate to excellent survival (5-year OS of 68.0-100%), while Group RB and MYC PB patients were much younger (median age 1.3-1.4 years) with dismal survival (5-year OS 37.5% and 28.6%, respectively). We identified age < 3 years at diagnosis, metastatic disease, omission of upfront radiation, and chr 16q loss as significant negative prognostic factors across all PBs. Our findings demonstrate that PB exhibits substantial molecular heterogeneity with sub-group-associated clinical phenotypes and survival. In addition to revealing novel biology and therapeutics, molecular sub-grouping of PB can be exploited to reduce treatment intensity for patients with favorable biology tumors.

Predictors of Success of Phase II Pediatric Oncology Clinical Trials.

BACKGROUND: There are limited data to predict which novel childhood cancer therapies are likely to be successful. To help rectify this, we sought to identify the factors that impact the success of phase II clinical trials for pediatric malignancies. MATERIALS AND METHODS: We examined the impact of 24 preclinical and trial design variables for their influence on 132 phase II pediatric oncology clinical trials. Success was determined by an objective assessment of patient response, with data analyzed using Fisher's exact test, Pearson's chi-square test, and logistic regression models. RESULTS: Trials that evaluated patients with a single histological cancer type were more successful than those that assessed multiple different cancer types (68% vs. 47%, 27%, and 17% for 1, 2-3, 4-7, and 8+; p < .005). Trials on liquid or extracranial solid tumors were more successful than central nervous system or combined trials (70%, 60%, 38%, and 24%; p < .005), and trials of combination therapies were more successful than single agents (71% vs. 28%; p < .005). Trials that added therapies to standard treatment backbones were more successful than trials testing novel therapies alone or those that incorporated novel agents (p < .005), and trials initiated based on the results of adult studies were less likely to succeed (p < .05). For 61% of trials (80/132), we were unable to locate any relevant preclinical findings to support the trial. When preclinical studies were carried out (52/132), there was no evidence that the conduct of any preclinical experiments made the trial more likely to succeed (p < .005). CONCLUSION: Phase II pediatric oncology clinical trials that examine a single cancer type and use combination therapies have the highest possibility of clinical success. Trials building upon a standard treatment regimen were also more successful. The conduct of preclinical experiments did not improve clinical success, emphasizing the need for a better understanding of the translational relevance of current preclinical testing paradigms. IMPLICATIONS FOR PRACTICE: To improve the clinical outcomes of phase II childhood cancer trials, this study identified factors impacting clinical success. These results have the potential to impact not only the design of future clinical trials but also the assessment of preclinical studies moving forward. This work found that trials on one histological cancer type and trials testing combination therapies had the highest possibility of success. Incorporation of novel therapies into standard treatment backbones led to higher success rates than testing novel therapies alone. This study found that most trials had no preclinical evidence to support initiation, and even when preclinical studies were available, they did not result in improved success.

Correction to: International experience in the development of patient-derived xenograft models of diffuse intrinsic pontine glioma.

There are two errors and one omission in the original article. Author Gottardo's correct name is Nicholas G. Gottardo, author Hulleman's correct affiliation is no. 3 (VUMC, Amsterdam), and the Acknowledgements should include the following sentence: "We would like to thank Dr Angel Montero Carcaboso (Hospital Sant Joan de Deu, Barcelona, Spain) for generously supplying the HSJD-DIPG007 cells."