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Purpose: Pediatric glioblastoma multiforme (pGBM) is a highly aggressive tumor in need of novel therapies. Our objective was to demonstrate the therapeutic efficacy of MLN8237 (alisertib), an orally available selective inhibitor of Aurora A kinase (AURKA), and to evaluate which in vitro model system (monolayer or neurosphere) can predict therapeutic efficacy in vivo.Experimental Design: AURKA mRNA expressions were screened with qRT-PCR. In vitro antitumor effects were examined in three matching pairs of monolayer and neurosphere lines established from patient-derived orthotopic xenograft (PDOX) models of the untreated (IC-4687GBM), recurrent (IC-3752GBM), and terminal (IC-R0315GBM) tumors, and in vivo therapeutic efficacy through log rank analysis of survival times in two models (IC-4687GBM and IC-R0315GBM) following MLN8237 treatment (30 mg/kg/day, orally, 12 days). Drug concentrations in vivo and mechanism of action and resistance were also investigated.Results: AURKA mRNA overexpression was detected in 14 pGBM tumors, 10 PDOX models, and 6 cultured pGBM lines as compared with 11 low-grade gliomas and normal brains. MLN8237 penetrated into pGBM xenografts in mouse brains. Significant extension of survival times were achieved in IC-4687GBM of which both neurosphere and monolayer were inhibited in vitro, but not in IC-R0315GBM of which only neurosphere cells responded (similar to IC-3752GBM). Apoptosis-mediated MLN8237 induced cell death, and the presence of AURKA-negative and CD133+ cells appears to have contributed to in vivo therapy resistance.Conclusions: MLN8237 successfully targeted AURKA in a subset of pGBMs. Our data suggest that combination therapy should aim at AURKA-negative and/or CD133+ pGBM cells to prevent tumor recurrence. Clin Cancer Res; 24(9); 2159–70. ©2018 AACR.

Supplementary Figure S1-S3 Figure S1. Anti-proliferative effects of MLN8237 on pGBM cell lines. Paired monolayer (Mono) and neurosphere (NS) of IC-4687GBM, IC-3752GBM and ICR0315GBM were seeded at 2,000 cells/well and exposed to MLN8237 (1 - 4,000 nM) and anti-proliferative effect was assessed by staining with 250 µg/mL of MTT for 4 hrs at day 11. Viable cells were stained with dark colored intracellular crystal. (Bar=100 µm) Figure S2. FCM analysis of cell cycle distribution in vitro and in vivo. A. In vitro analysis was performed in paired monolayer (Mono) and neurosphere (NS) cells of IC-4687GBM, IC-3752GBM and IC-R0315GBM. Both dose-responses (on day 7) (left panel) and time-course change (at 62.5 nM) (right panel) were examined and presented as percentages of G0 /G1 , S and G2 /M phase in alive cells. € P

Background : Growing teratoma syndrome is defined as conversion of a metastatic immature tumor to a mature tumor after adjuvant chemotherapy and remains an area of investigation because of its unclear pathogenesis. Because of its risk of malignant transformation, the primary treatment strategy for pediatric patients is surgical resection. Case : In this report we present a case of a pediatric patient with recurrent growing teratoma syndrome who was treated with chemotherapy, debulking procedures, and cryoablation for the growing nodules throughout her abdominal cavity. The patient has had a good clinical outcome without recurrent malignant tumor. Summary and Conclusion : These masses do not always regress with chemotherapy and complete surgical excision or ablation should be attempted when possible.

Olaratumab is a monoclonal antibody that specifically binds to platelet‐derived growth factor receptor alpha (PDGFRα) and blocks receptor activation. We conducted a phase 1 trial to evaluate the safety of olaratumab and determine a recommended dose in combination with three different chemotherapy regimens in children. Patients 25% of patients included neutropenia, anemia, leukopenia, lymphopenia, and thrombocytopenia. Pharmacokinetic profiles of olaratumab with chemotherapy were within the projected range based on adult data. There was one complete response (rhabdomyosarcoma [Part B vincristine/irinotecan arm]) and three partial responses (two rhabdomyosarcoma [Part A doxorubicin arm and Part C doxorubicin arm]; one pineoblastoma [Part B vincristine/irinotecan arm]). Olaratumab was tolerable and safely administered in combination with chemotherapy regimens commonly used in children and adolescents., Observed pharmacokinetic (PK) data and model predicted PK profiles by weight in pediatric patients treated with olaratumab. The overlay was limited to the first seven cycles where observed data were available to provide meaningful comparison. Overall, there was general agreement between the observed and model predicted serum concentrations as the observed values (colored circle) overlap with the prediction interval (shaded region) from the PK model. The colored circles correspond to each patient in the study. The shaded region represents the 90% prediction interval and the solid line represents the median of predicted concentration.

Background Aromatase inhibitors (AIs) are used for estrogen-modulated conditions. Some borderline ovarian tumors (BOT) express estrogen receptors. We present 2 cases of progression from mucinous cystadenoma to mucinous BOT (mBOT) after prior cystectomies in whom an AI was used with recurrence prevention. Cases Two patients underwent laparoscopic ovarian cystectomy for mucinous cystadenoma. Serial imaging demonstrated recurrent ovarian cysts for which both underwent fertility sparing surgery (FSS) with ovarian cystectomy for mBOT. Both patients were initiated on an AI and have been without recurrence. Summary and Conclusion BOT predominantly occur in reproductive aged females. FSS with cystectomy is an option, but recurrence occurs in 12-36% of cases. The use of AI in prevention of recurrent BOT shows promise, and more studies are needed to explore this treatment.

Pediatric germ cell tumors (GCTs) are neoplasms that originate from primordial germ cells and, according to their site of presentation, are classified as gonadal or extragonadal. The most common site of extragonadal GCTs in children is the sacrococcygeal region, and the standard management is multimodal with a focus on chemotherapy. In selected instances, sacrococcygeal resection is performed. Herein, the authors report on 2 patients who presented with presacral yolk sac tumors managed with multimodal treatment. Both patients underwent salvage sacrococcygeal resection for oncological control and surgical removal of the sacral vertebral elements: a 27-month-old girl with a recurrent sacrococcygeal yolk sac tumor following chemotherapy and initial resection and a 24-month-old boy in whom a primary sacrococcygeal yolk sac tumor was resected following chemotherapy. These 2 cases illustrate the complexity in the management of these unusual tumors and will help neurosurgeons with the understanding of yolk sac tumors in the sacrococcygeal region.

TPS11583 Background: Palbociclib (PD-0332991) is a highly selective, reversible, small molecule inhibitor of cyclin-dependent kinases (CDK) 4 and 6, administered orally. Functional dependence of Ewing Sarcoma (EWS) cell lines and tumor xenografts on Cyclin D1/CDK4 via genetic knockdown has shown both Cyclin D1 and CDK4 as critical dependencies for EWS cell line proliferation. The phase 1 portion of the study established the recommended Phase 2 dose (RP2D) with two chemotherapy backbones in children with solid tumors. The Phase 2 portion of the study now enrolls patients with EWS. The primary objective of this portion of the study is to determine whether the addition of palbociclib to irinotecan (IRN) and temozolomide (TMZ) will prolong event-free survival (EFS) of pediatric and young adult patients with recurrent or refractory EWS. Methods: Patients with recurrent or refractory EWS are randomized 2:1 to receive either palbociclib in combination with IRN and TMZ or IRN and TMZ alone. Randomization is stratified by type and time of disease recurrence (primary refractory or 1st recurrence st recurrence ≥2 years or 2nd or greater recurrence). The primary efficacy endpoint is EFS per investigator assessment. Secondary efficacy endpoints include objective response, progression-free survival and overall survival. An interim futility analysis will be conducted to allow for early stopping of the study due to futility/no signal of activity based on the primary endpoint of EFS. Safety and planned interim efficacy data will be assessed by an Independent Data Monitoring Committee (DMC). Key eligibility criteria include: recurrent or refractory EWS with evaluable disease, no known bone marrow metastases, histopathological confirmation of EWSR1-ETS or FUS-ETS rearrangement or availability of formalin fixed paraffin embedded (FFPE) tumor tissue sample for central testing, age ≥2 and 2 orally (either as a capsule or oral solution) once daily on Days 1-14 of each 21-day treatment cycle. TMZ will be administered orally once daily at 100 mg/m2 on Days 1-5 (intravenously (IV) if patient cannot swallow the TMZ capsule). IRN will be administered IV at 50 mg/m2 on Days 1-5. Patients randomized to the chemotherapy only treatment arm will receive IRN and TMZ at the same doses on Days 1-5 of the 21-day treatment cycle. Treatment will continue until disease progression, patient and/or legal guardian refusal, unacceptable toxicity , or up to 24 months of treatment, whichever occurs first. The Phase 2 enrolment has been initiated and 1/75 patients has been enrolled as of Jan 2022. Clinical trial information: NCT03709680.

Purpose: Pediatric glioblastoma multiforme (pGBM) is a highly aggressive tumor in need of novel therapies. Our objective was to demonstrate the therapeutic efficacy of MLN8237 (alisertib), an orally available selective inhibitor of Aurora A kinase (AURKA), and to evaluate which in vitro model system (monolayer or neurosphere) can predict therapeutic efficacy in vivo. Experimental Design: AURKA mRNA expressions were screened with qRT-PCR. In vitro antitumor effects were examined in three matching pairs of monolayer and neurosphere lines established from patient-derived orthotopic xenograft (PDOX) models of the untreated (IC-4687GBM), recurrent (IC-3752GBM), and terminal (IC-R0315GBM) tumors, and in vivo therapeutic efficacy through log rank analysis of survival times in two models (IC-4687GBM and IC-R0315GBM) following MLN8237 treatment (30 mg/kg/day, orally, 12 days). Drug concentrations in vivo and mechanism of action and resistance were also investigated. Results: AURKA mRNA overexpression was detected in 14 pGBM tumors, 10 PDOX models, and 6 cultured pGBM lines as compared with 11 low-grade gliomas and normal brains. MLN8237 penetrated into pGBM xenografts in mouse brains. Significant extension of survival times were achieved in IC-4687GBM of which both neurosphere and monolayer were inhibited in vitro, but not in IC-R0315GBM of which only neurosphere cells responded (similar to IC-3752GBM). Apoptosis-mediated MLN8237 induced cell death, and the presence of AURKA-negative and CD133+ cells appears to have contributed to in vivo therapy resistance. Conclusions: MLN8237 successfully targeted AURKA in a subset of pGBMs. Our data suggest that combination therapy should aim at AURKA-negative and/or CD133+ pGBM cells to prevent tumor recurrence. Clin Cancer Res; 24(9); 2159–70. ©2018 AACR.

Study Objective To determine the diagnosis, management, and outcome for children and adolescents with borderline ovarian tumor (BOT), and to provide a review of the literature on BOT in children and adolescents. Design A retrospective cohort study of female adolescents younger than age 21 years diagnosed with BOT between January 2001 and May 2016. Setting Texas Children's Hospital, Houston, Texas. Participants Fourteen patients (ages 12 to 18 years) diagnosed with BOT. Main Outcome Measures Clinical presentation, preoperative characteristics, surgical technique, cancer stage, histology, treatment, and recurrence. Results Median age at diagnosis was 15.5 years, with most postmenarchal. Abdominal mass/pain were the most common presenting symptoms. Median tumor size was 16.6 cm (range, 4-32 cm). Preoperative cancer antigen 125 (CA 125) was elevated in 54% (7/13) of cases. All patients had fertility-preserving surgery, either cystectomy (CY) or unilateral salpingo-oophorectomy (USO): 5 via laparoscopy (LSC) and 9 via laparotomy. Most were stage I with 5 serous and 9 mucinous BOT histology. No one received adjuvant chemotherapy. Two patients had recurrence. One had ipsilateral recurrence 2 months after LSC CY for FIGO stage IC1 mucinous BOT. The second had contralateral recurrence 15 months after laparotomy, right USO for FIGO stage IIIC serous BOT treated with LSC CY, then a second recurrence treated with USO after oocyte cryopreservation for fertility preservation. All patients were alive at last follow-up, 1 with disease. Conclusions BOT in children and adolescents can be treated conservatively with fertility-preserving techniques and surveillance with good outcome. The role of adjuvant therapy is not known.

Neuroblastoma (NB), the most common extracranial pediatric solid tumor, continues to cause significant cancer-related morbidity and mortality in children. Dysregulation of oncogenic receptor tyrosine kinases (RTKs) has been shown to contribute to tumorigenesis in various human cancers and targeting these RTKs has had therapeutic benefit. RET is an RTK which is commonly expressed in NB, and high expression of RET correlates with poor outcomes in patients with NB. Herein we report that RET is required for NB cell proliferation and that the small molecule inhibitor regorafenib (BAY 73-4506) blocks glial cell derived neurotrophic factor (GDNF)-induced RET signaling in NB cells and inhibits NB growth both in vitro and in vivo. We found that regorafenib significantly inhibited cell proliferation and colony formation ability of NB cells. Moreover, regorafenib suppressed tumor growth in both an orthotopic xenograft NB mouse model and a TH-MYCN transgenic NB mouse model. Finally, regorafenib markedly improved the overall survival of TH-MYCN transgenic tumor-bearing mice. In summary, our study suggests that RET is a potential therapeutic target in NB, and that using a novel RET inhibitor, like regorafenib, should be investigated as a therapeutic treatment option for children with NB.

Activating germline mutations of anaplastic lymphoma kinase (ALK) occur in most cases of hereditary neuroblastoma (NB) and the constitutively active kinase activity of ALK promotes cell proliferation and survival in NB. Therefore, ALK kinase is a potential therapeutic target for NB. In this study, we show that the novel ALK inhibitor alectinib effectively suppressed cell proliferation and induces apoptosis in NB cell lines with either wild-type ALK or mutated ALK (F1174L and D1091N) by blocking ALK-mediated PI3K/Akt/mTOR signaling. In addition, alectinib enhanced doxorubicin-induced cytotoxicity and apoptosis in NB cells. Furthermore, alectinib induced apoptosis in an orthotopic xenograft NB mouse model. Also, in the TH-MYCN transgenic mouse model, alectinib resulted in decreased tumor growth and prolonged survival time. These results indicate that alectinib may be a promising therapeutic agent for the treatment of NB.

Clear cell sarcoma of the kidney (CCSK) is the second most common malignant pediatric renal tumor. Two of the recurrent somatic alterations reported in CCSK are BCL-6 corepressor (BCOR) internal tandem duplication (ITD) and YWHAE-NUTM2B/E gene fusion. A minority of patients with CCSKs have other rare somatic alterations. We report two patients with CCSK showing BCOR-CCNB3 (where CCNB3 is cyclin B3) fusion, who had similar clinical presentation of a large renal mass with tumor thrombus extending through the inferior vena cava into the right atrium and a favorable response to chemotherapy. We recommend BCOR-CCNB3 fusion testing for all patients with CCSK who lack BCOR-ITD or YWHAE-NUTM2B/E gene fusions.

BACKGROUND Identification and development of young investigators (YI) is critical to the long-term success of research organizations. In 2004, the Children's Oncology Group (COG) created a mentorship program to foster the career development of YIs (faculty

// Shayahati Bieerkehazhi 1, 2, * , Zhenghu Chen 3, 4, * , Yanling Zhao 4 , Yang Yu 4 , Huiyuan Zhang 4 , Sanjeev A. Vasudevan 5 , Sarah E. Woodfield 5 , Ling Tao 4 , Joanna S. Yi 4 , Jodi A. Muscal 4 , Jonathan C. Pang 4, 6 , Shan Guan 4 , Hong Zhang 2 , Jed G. Nuchtern 5 , Hui Li 7 , Huiwu Li 8 , Jianhua Yang 4 1 Department of Labour Hygiene and Sanitary Science, College of Public Health, Xinjiang Medical University, Urumqi, Xinjiang 830011, P.R. China 2 Department of Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA 3 Department of Ophthalmology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai 200072, P. R. China 4 Texas Children's Cancer Center, Department of Pediatrics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA 5 Division of Pediatric Surgery, Texas Children’s Hospital Department of Surgery, Michael E. DeBakey Department of Surgery, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, Texas 77030, USA 6 Department of Biosciences, Weiss School of Natural Sciences, Rice University, Houston, Texas 77005, USA 7 Central Laboratory of Xinjiang Medical University, Urumqi, Xinjiang 830011, P.R. China 8 Cancer Prevention and Research Institute, The Affiliated Tumor Hospital of Xinjiang Medical University, Urumqi, Xinjiang 830011, P.R. China * These authors have contributed equally to this work and should be considered co-first authors Correspondence to: Huiwu Li, email: huiwuli1234@163.com Jianhua Yang, email: jianhuay@bcm.edu Keywords: neuroblastoma, bosutinib, SKI-606, Bosulif, chemotherapy Received: October 29, 2016 Accepted: November 12, 2016 Published: November 26, 2016 ABSTRACT Neuroblastoma (NB) is the most common extracranial solid tumor in children. Aberrant activation of the non-receptor tyrosine kinases Src and c-Abl contributes to the progression of NB. Thus, targeting these kinases could be a promising strategy for NB therapy. In this paper, we report that the potent dual Src/Abl inhibitor bosutinib exerts anti-tumor effects on NB. Bosutinib inhibited NB cell proliferation in a dose-dependent manner and suppressed colony formation ability of NB cells. Mechanistically, bosutinib effectively decreased the activity of Src/Abl and PI3K/AKT/mTOR, MAPK/ERK, and JAK/STAT3 signaling pathways. In addition, bosutinib enhanced doxorubicin (Dox)- and etoposide (VP-16)-induced cytotoxicity in NB cells. Furthermore, bosutinib demonstrated anti-tumor efficacy in an orthotopic xenograft NB mouse model in a similar mechanism as of that in vitro . In summary, our results reveal that Src and c-Abl are potential therapeutic targets in NB and that the novel Src/Abl inhibitor bosutinib alone or in combination with other chemotherapeutic agents may be a valuable therapeutic option for NB patients.

Tracheobronchial mucoepidermoid carcinomas (MEC) are rare in the pediatric population with literature limited primarily to case reports. Here we present our institutional experience treating MEC in three patients and review the literature of 142 pediatric cases previously published from 1968 to 2013. Although rare, tracheobronchial MEC should be included in the differential diagnosis in a child with recurrent respiratory symptoms. Conservative surgical management is often sufficient to achieve complete resection and good outcomes.

Background Mentorship of junior faculty is an integral component of career development. The Children's Oncology Group (COG) Young Investigator (YI) Committee designed a mentorship program in 2004 whose purpose was to pair YIs (faculty ≤10 years of first academic appointment) with a senior mentor to assist with career development and involvement in COG research activities. This study reports on the committee's ability to achieve these goals. Procedure An online survey was sent to YIs who were registered with the program from 2004 to2015, assessing three major domains: (1) overall experience with the mentor pairing, (2) satisfaction with the program, and (3) academic accomplishments of the mentees. Results The response rate was 64% (110/171). Overall, YIs rated the success of their mentorship pairing as 7.2 out of 10 (median) (25th, 75th quartile 3.6, 9.6). The direct effects of the mentorship program included 70% YIs reporting a positive effect on their career, 40% reporting any grant or manuscript resulting from the pairing, 47% forming a new research collaboration, and 43% receiving appointment to a COG committee. Respondents reported success in COG with 38% authoring a manuscript on behalf of COG and 65% reporting a leadership position including seven current or past COG discipline chairs and 20 study chairs. Finally, 74% of respondents said they would consider serving as mentors in the program in the future. Conclusion The COG YI mentorship program has been well received by the majority of the participants and has helped to identify and train many current leaders in COG.

Background EZN-2208 is a water-soluble PEGylated conjugate of the topoisomerase inhibitor SN38, the active metabolite of irinotecan. Compared to irinotecan, EZN-2208 has a prolonged half-life permitting extended exposure to SN38. EZN-2208 has demonstrated clinical tolerability and antitumor activity in adults with advanced solid tumors. This Phase 1 study evaluated the safety, pharmacokinetics, and preliminary antitumor activity of EZN-2208 in children with relapsed or refractory solid tumors. Procedure EZN-2208 was administered as a 1-hour intravenous infusion once every 21 days at five dose levels (12–30 mg/m2). Filgrastim or pegfilgrastim was administered 24–48 hours after treatment with EZN-2208. The rolling-six design was used for dose determination. Results Thirty eligible patients (15 females; median [range] age 11.5 years [2–21 years]) were treated with EZN-2208. Dose-limiting diarrhea occurred in one patient receiving 16 mg/m2 and dose-limiting dehydration was seen in one patient receiving 24 mg/m2. At dose levels above 16 mg/m2, Grade ≥3 myelosuppression was demonstrated in the majority of patients. Additional adverse events included nausea, vomiting, and fatigue. The maximum tolerated dose was identified as 24 mg/m2 due to dose-limiting thrombocytopenia in two patients receiving 30 mg/m2. Two of nine patients with neuroblastoma who were evaluable for response had partial responses. Five patients (four with neuroblastoma) remained on study for ≥8 cycles. Conclusions EZN-2208 was generally well-tolerated and was associated with clinical benefit in patients with neuroblastoma. Pediatr Blood Cancer 2014; 61:1792–1797. © 2014 Wiley Periodicals, Inc.

BACKGROUND: TP53 mutations are rare across pediatric cancers. Recent work using CRISPR-Cas9 screens has demonstrated that MDM2 and MDMX are strong dependencies in a range of TP53-wildtype pediatric malignancies. Increased expression of MDM2 and MDMX is a common mechanism for suppressing p53 in pediatric malignancies and can occur by copy number gain or amplification, as has been reported in retinoblastoma and hepatoblastoma. In pediatric high-grade gliomas, activating PPM1D mutations drive p53 suppression, likely through MDM2 stabilization. ALRN-6924 is a novel, first-in-class, cell-permeating stapled peptide that disrupts the inhibitory interactions between MDM2/MDMX(MDM4) and p53. ALRN-6924 has been evaluated in two adult Phase I trials, with good tolerability and evidence of clinical activity across a range of cancer subtypes. Given the oncogenic roles of MDM2 and MDMX in pediatric malignancies, we developed a Phase I clinical trial designed to evaluate the tolerability, pharmacokinetics, and pharmacodynamic and antitumor activity of ALRN-6924. METHODS: This is a Phase I, open-label, investigator-initiated multicenter study of ALRN-6924 in children 1-21 years of age with relapsed/refractory cancer (NCT03654716). The primary objectives are to determine the recommended phase 2 dose, and to describe toxicities and pharmacokinetic parameters of ALRN-6924 in this population. The monotherapy arm consists of two cohorts: Cohort A for patients with TP53-wildtype solid tumors and lymphomas; and Cohort B for patients with retinoblastoma, or TP53-wildtype tumors that meet any of the following criteria: hepatoblastoma, malignant rhabdoid tumor, MDM2 or MDMX amplification, TET2 loss, or PPM1D activating mutations. Patients with CNS primary tumors are only eligible for Cohort B. In Cohorts A and B, patients receive ALRN-6924 intravenously on Days 1, 4, 8 and 11 of a 21-day cycle starting at a dose of 2.2 mg/kg. An expansion cohort for patients eligible for Cohort B will open following completion of monotherapy dose escalation. Patients with relapsed/refractory leukemias enroll to Cohort C and receive ALRN-6924 in combination with low-dose cytarabine on days 1, 8 and 15 of a 28-day cycle starting at a dose of 2.7 mg/kg. Pharmacokinetic sampling and pharmacodynamic testing (serum MIC-1 modulation) is required for all patients. Correlative biology studies will include evaluation of circulating tumor DNA for TP53 mutations in patients with solid tumors and serial assessment of leukemic blasts in patients with relapsed leukemia. Enrollment began in October 2018. Up to 69 patients will be enrolled. Citation Format: David S. Shulman, Kieuhoa T. Vo, Elizabeth Fox, Jodi A. Muscal, Loren D. Walensky, Yana Pikman, Kimberly Stegmaier, Alanna Church, Brian D. Crompton, Andrew E. Place, Susan N. Chi, Allison F. O'Neill, Junne Kamihara, Suzanne Ezrre, Cecilia Carlowicz, Dawn Pinchasik, Hasan Al-Sayegh, Clement Ma, Wendy B. London, Steven G. DuBois. A Phase I multicenter trial of the dual MDM2/MDMX inhibitor ALRN-6924 in children and young adults with relapsed/refractory pediatric cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr CT112.

e21521 Background: Pevonedistat, a first in class inhibitor of NEDD8 activating enzyme (NAE), prevents the activation of Cullin-RING ligases (CRL) necessary for proteasome mediated degradation of key regulatory proteins important in cell survival. In adults with solid tumors, the maximum tolerated dose (MTD) in combination with chemotherapy is 20-25 mg/m2. Antitumor activity of pevonedistat has been demonstrated in preclinical models of childhood cancer. In vivo additive activity has been demonstrated for pevonedistat in combination with IRN and alkylating agents. The objectives of this study are to determine the MTD and recommended phase 2 dose of pevonedistat in combination with IRN and TMZ and describe the toxicities, pharmacokinetic (PK), and pharmacodynamics (PD) properties of this combination. Methods: Using a rolling six design, we conducted a phase 1 trial of pevonedistat in combination with IRN and TMZ in pediatric patients (pts) with recurrent or refractory solid tumors and brain tumors. During cycle 1, pevonedistat was administered intravenously on days 1, 8, 10, and 12, with IRN (IV, 50mg/m2) and TMZ (orally, 100mg/m2), on days 8-12 of a 28 day cycle. In subsequent cycles, pevonedistat was administered on days 1, 3, and 5, with IRN and TMZ on days 1-5 of a 21 day cycle. Results: 18 pts enrolled. All pts were eligible and evaluable for cycle 1 dose limiting toxicity (DLT) assessment. Median (range) age was 13 (1-21) years; 11 (61%) were male. Six pts had brain tumors, and 12 pts had solid tumors. Six pts each enrolled on pevonedistat dose levels 1 (15mg/m2), 2 (20mg/m2), and 3 (25mg/m2). There were no DLTs; DLT assessment is pending for 1 pt on dose level 3. Grade 3/4 toxicities included grade 4 lymphocyte count decreased (n = 2), grade 3 white blood cell decreased (n = 2), and 1 pt each with grade 3 anemia, elevated AST, and elevated ALT. The most frequent AEs were anemia (83%), nausea (61%), elevated AST (61%), and diarrhea (61%). Pharmacokinetic analysis is pending. Conclusions: Pevonedistat in combination with IRN and TMZ is well tolerated in pts with solid or brain tumors. PK and PD analyses are ongoing to establish the recommended dose. Clinical trial information: NCT03323034.

Purpose: Imetelstat is a covalently-lipidated 13-mer thiophosphoramidate oligonucleotide that acts as a potent specific inhibitor of telomerase. It binds with high affinity to the template region of the RNA component of human telomerase (hTERC) and is a competitive inhibitor of telomerase enzymatic activity. The purpose of this study was to determine the recommended phase II dose of imetelstat in children with recurrent or refractory solid tumors. Experimental Design: Imetelstat was administered intravenously more than two hours on days 1 and 8, every 21 days. Dose levels of 225, 285, and 360 mg/m2 were evaluated, using the rolling-six design. Imetelstat pharmacokinetic and correlative biology studies were also performed during the first cycle. Results: Twenty subjects were enrolled (median age, 14 years; range, 3–21). Seventeen were evaluable for toxicity. The most common toxicities were neutropenia, thrombocytopenia, and lymphopenia, with dose-limiting myelosuppression in 2 of 6 patients at 360 mg/m2. Pharmacokinetics is dose dependent with a lower clearance at the highest dose level. Telomerase inhibition was observed in peripheral blood mononuclear cells at 285 and 360 mg/m2. Two confirmed partial responses, osteosarcoma (n = 1) and Ewing sarcoma (n = 1), were observed. Conclusions: The recommended phase II dose of imetelstat given on days 1 and 8 of a 21-day cycle is 285 mg/m2. Clin Cancer Res; 19(23); 6578–84. ©2013 AACR.

Background A pediatric Phase I trial was performed to determine the maximum-tolerated dose, dose-limiting toxicities (DLTs), and pharmacokinetics (PK) of vorinostat and bortezomib, in patients with solid tumors. Procedure Oral vorinostat was administered on days 1–5 and 8–12 of a 21-day cycle (starting dose 180 mg/m2/day with dose escalations to 230 and 300 mg/m2/day). Bortezomib (1.3 mg/m2 i.v.) was administered on days 1, 4, 8, and 11 of the same cycle. PK and correlative biology studies were performed during Cycle 1. Results Twenty-three eligible patients [17 male, median age 12 years (range: 1–20)] were enrolled of whom 17 were fully evaluable for toxicity. Cycle 1 DLTs that occurred in 2/6 patients at dose level 3 (vorinostat 300 mg/m2/day) were Grade 2 sensory neuropathy that progressed to Grade 4 (n = 1) and Grade 3 nausea and anorexia (n = 1). No objective responses were observed. There was wide interpatient variability in vorinostat PK parameters. Bortezomib disposition was best described by a three-compartment model that demonstrated rapid distribution followed by prolonged elimination. We did not observe a decrease in nuclear factor-κB activity or Grp78 induction after bortezomib treatment in peripheral blood mononuclear cells from solid tumor patients. Conclusion The recommended Phase 2 dose and schedule is vorinostat (230 mg/m2/day PO on days 1–5 and 8–12) in combination with bortezomib (1.3 mg/m2/day i.v. on days 1, 4, 8, and 11 of a 21-day cycle) in children with recurrent or refractory solid tumors. Pediatr Blood Cancer 2013; 60: 390–395. © 2012 Wiley Periodicals, Inc.

Thalidomide, originally developed as a sedative, was subsequently identified to have antiangiogenic properties. Lenalidomide is an antiangiogenic and immunomodulatory agent that has been utilized in the treatment of patients with brain tumors. We studied the pharmacokinetics and cerebrospinal fluid (CSF) penetration of thalidomide and lenalidomide in a nonhuman primate model.A dose of 50 mg of thalidomide or 20 mg of lenalidomide was administered once orally to each of three rhesus monkeys. Plasma and CSF samples were obtained at specified intervals, and the thalidomide or lenalidomide concentrations were determined by high-performance liquid chromatography with tandem mass spectrometry. Pharmacokinetic parameters were estimated using noncompartmental methods. CSF penetration was calculated as area under the concentration-time curve (AUC) CSF/AUC plasma.For thalidomide, the median apparent clearance (Cl/F) was 2.9 mL/min/kg, the median plasma AUC was 80 μM h, and the median terminal half-life (t(½)) was 13.3 h. For lenalidomide, the median Cl/F was 8.7 mL/min/kg, the median AUC was 9 μM h, and the median t(½) was 5.6 h. Thalidomide was detected in the CSF of all animals, with a median penetration of 42%. Lenalidomide was detected in the CSF of 2 of 3 animals, with a CSF penetration of 11% in each.Thalidomide and lenalidomide penetrate into the CSF after oral administration of clinically relevant doses. Plasma exposure to lenalidomide was similar in our model to that observed in studies involving children who have brain tumors. These results support further development of lenalidomide for the treatment of central nervous system malignancies.

ALK receptor tyrosine kinase has been shown to be a therapeutic target in neuroblastoma. Germline ALK activating mutations are responsible for the majority of hereditary neuroblastoma and somatic ALK activating mutations are also frequently observed in sporadic cases of advanced NB. Crizotinib, a first-line therapy in the treatment of advanced non-small cell lung cancer (NSCLC) harboring ALK rearrangements, demonstrates striking efficacy against ALK-rearranged NB. However, crizotinib fails to effectively inhibit the activity of ALK when activating mutations are present within its kinase domain, as with the F1174L mutation. Here we show that a new ALK inhibitor AZD3463 effectively suppressed the proliferation of NB cell lines with wild type ALK (WT) as well as ALK activating mutations (F1174L and D1091N) by blocking the ALK-mediated PI3K/AKT/mTOR pathway and ultimately induced apoptosis and autophagy. In addition, AZD3463 enhanced the cytotoxic effects of doxorubicin on NB cells. AZD3463 also exhibited significant therapeutic efficacy on the growth of the NB tumors with WT and F1174L activating mutation ALK in orthotopic xenograft mouse models. These results indicate that AZD3463 is a promising therapeutic agent in the treatment of NB.

To determine the clinicopathologic and molecular features and outcome of children with mucoepidermoid carcinoma (MEC).A retrospective analysis of clinical and histopathologic findings was performed in patients with MEC diagnosed at Texas Children's Cancer Center between 2000 and 2014.Ten female and four male patients with median age 12 years (range 7-19 years) were included in the study. Tumors involved major salivary glands, minor salivary glands of the palate, and the tracheobronchial tree. Nine of 11 patients with salivary MEC underwent more than one surgical resection at the time of initial diagnosis to achieve a gross total resection. Three patients with tracheobronchial tumors underwent pulmonary lobectomy. Three patients received postoperative radiation therapy. No patient was treated with chemotherapy. Histopathologic grades were classified as low (n = 2), intermediate (n = 9), and high (n = 3). All 12 patients with tumor tissue available for testing were positive for MECT1/MAML2 fusion transcripts. There were no deaths, metastases, or recurrences in this series, with a median follow-up of 24 months (range 5-96 months).Low to intermediate histopathologic grade MECs are more common than high grade MEC in children. In contrast to adults, MECT1/MAML2 fusion transcripts occur with a frequency of 100% in our pediatric MEC series. Complete excision is the treatment of choice and is associated with excellent outcome. The role of radiotherapy is unclear, but may be indicated in patients with high grade tumors with positive surgical margins.

TPS10576 Background: CUDC-907 is an oral first-in-class small molecule inhibitor of histone deacetylases (HDACs) and phosphatidylinositol-3-kinases (PI3Ks), two enzyme classes commonly implicated in pediatric malignancies. Preclinical data demonstrate that inhibition of these enzymes decreases tumor growth across a range of histologies. Data from preclinical and clinical studies suggest that down-regulation of Myc or Mycn signaling may be important in the antineoplastic effects of CUDC-907. Myc or Mycn signaling appears to drive a number of pediatric cancers, heralds a poor prognosis in many of these diseases and has proven difficult to target. CUDC-907 has completed adult phase I testing in patients with hematologic malignancies. The drug was tolerable using a 5 days on/2 days off (5/2) dosing strategy, with a recommended phase II dose of 60 mg. Diarrhea, fatigue, nausea and thrombocytopenia were the most commonly reported side effects. Partial and complete responses were observed in patients with Myc-altered diffuse large B cell lymphoma. Methods: This study is a phase I, open-label, multicenter trial of CUDC-907 in patients 1-21 years of age with relapsed/refractory solid tumors, brain tumors and lymphomas (NCT02909777). The primary objectives are to determine the recommended phase II dose, describe toxicities, and describe pharmacokinetic parameters of CUDC-907 in this population. Other objectives include evaluation of disease response and exploration of the pharmacodynamic effects of CUDC-907. Patients receive CUDC-907 orally on a 5/2 schedule in 28-day cycles, with a pediatric mini-tab formulation available for younger children. Part A consists of a standard 3+3 design evaluating up to three dose levels. Following dose escalation, Part B consists of two expansion cohorts for patients with Mycn/Myc-driven neuroblastoma or mature B-cell lymphoma. Up to 44 patients may be enrolled across Parts A and B. Detailed pharmacokinetic testing is required in the first two cycles. Optional pharmacodynamic testing will quantify histone acetylation, Myc protein, and phospho-S6 in serial blood samples. Enrollment began in October 2016 and is ongoing. Clinical trial information: NCT02909777.

EZN-2208 is a water-soluble PEGylated conjugate of the topoisomerase inhibitor SN38, the active metabolite of irinotecan. Compared to irinotecan, EZN-2208 has a prolonged half-life permitting extended exposure to SN38. EZN-2208 has demonstrated clinical tolerability and antitumor activity in adults with advanced solid tumors. This Phase 1 study evaluated the safety, pharmacokinetics, and preliminary antitumor activity of EZN-2208 in children with relapsed or refractory solid tumors.EZN-2208 was administered as a 1-hour intravenous infusion once every 21 days at five dose levels (12-30 mg/m(2) ). Filgrastim or pegfilgrastim was administered 24-48 hours after treatment with EZN-2208. The rolling-six design was used for dose determination.Thirty eligible patients (15 females; median [range] age 11.5 years [2-21 years]) were treated with EZN-2208. Dose-limiting diarrhea occurred in one patient receiving 16 mg/m(2) and dose-limiting dehydration was seen in one patient receiving 24 mg/m(2) . At dose levels above 16 mg/m(2) , Grade ≥3 myelosuppression was demonstrated in the majority of patients. Additional adverse events included nausea, vomiting, and fatigue. The maximum tolerated dose was identified as 24 mg/m(2) due to dose-limiting thrombocytopenia in two patients receiving 30 mg/m(2) . Two of nine patients with neuroblastoma who were evaluable for response had partial responses. Five patients (four with neuroblastoma) remained on study for ≥8 cycles.EZN-2208 was generally well-tolerated and was associated with clinical benefit in patients with neuroblastoma.

Purpose Histone deacetylase (HDAC) inhibitors, such as vorinostat, decrease Aurora kinase activity by a variety of mechanisms. Vorinostat and MLN8237, a selective Aurora A kinase inhibitor, disrupt the spindle assembly and the mitotic checkpoint at different points, suggesting that the combination could have increased antitumor activity. The purpose of this study was to determine the cytotoxicity of vorinostat and MLN8237 in pediatric tumor cell lines. Methods Cell survival was measured after 72 h of drug treatment using a modified methyl tetrazolium assay. For drug combination experiments, cells were exposed to medium alone (controls), single drug alone, or to different concentrations of the combination of the two drugs, for a total of 36 concentration pairs per plate. The interaction of the drug combination was analyzed using the universal response surface approach. Results The cells express the target of MLN8237, Aurora A. For each cell line, the single agent IC50 for MLN8237 and for vorinostat was in the clinically relevant range. Both drugs inhibited cell survival in a concentration-dependent fashion. At concentrations of MLN8237 exceeding approximately 1 μM, there was a paradoxical increase in viability signal in all three lines that may be explained by inhibition of Aurora B kinase. The combination of MLN8237 and vorinostat showed additive cytotoxicity in all three cell lines and nearly abrogated the paradoxical increase in survival noted at high single-agent MLN8237 concentrations. Conclusion MLN8237 and vorinostat are active in vitro against cancer cell lines. These results provide important preclinical support for the development of future clinical studies of MLN8237and vorinostat.

ABT-888 inhibits poly(ADP-ribose) polymerase (PARP) and may enhance the efficacy of chemotherapy and radiation in CNS tumors. We studied the plasma and cerebrospinal fluid (CSF) pharmacokinetics (PK) of ABT-888 in a non-human primate (NHP) model that is highly predictive of human CSF penetration.ABT-888, 5 mg/kg, was administered orally to three NHPs. Serial blood and CSF samples were obtained. Plasma and CSF concentrations of ABT-888 were measured using LC/MS/MS, and the resulting concentration versus time data were evaluated using non-compartmental and compartmental PK methods.The CSF penetration of ABT-888 was 57+/-7% (mean+/-SD). The peak ABT-888 concentration in the plasma was 0.62+/-0.18 microM. Plasma and CSF AUC0-infinity were 3.7+/-1.7 and 2.1+/-0.8 microM h. PARP inhibition in peripheral blood mononuclear cells was evident 2 h after ABT-888 administration.The CSF penetration of ABT-888 after oral administration was 57%. Plasma and CSF concentrations were in the range that has been shown to inhibit PARP activity in vivo in humans.

Purpose Acute and late changes in magnetic resonance imaging of the pediatric brain have been described after radiotherapy (RT). We report the post-RT neuroimaging changes in the posterior fossa after intensity-modulated RT (IMRT) in children with medulloblastoma and contrast them with those of leptomeningeal disease. Methods and Materials We performed a retrospective review of 53 consecutive children with medulloblastoma who were treated with craniospinal RT followed by IMRT to the posterior fossa and chemotherapy between 1997 and 2006. Results After IMRT to the posterior fossa, 8 (15%) of 53 patients developed increased fluid-attenuated inversion-recovery signal changes in the brainstem or cerebellum and patchy, multifocal, nodular contrast enhancement at a median of 6 months. The enhancement superficially resembled leptomeningeal disease. However, the enhancement resolved without intervention at a median of 6 months later. The accompanying fluid-attenuated inversion-recovery signal changes occasionally preceded the enhancement, were often parenchymal in location, and resolved or persisted to a lesser degree. All 8 patients with transient magnetic resonance imaging changes in the posterior fossa were alive at last follow-up. In contrast, leptomeningeal disease occurred in 8 (15%) of our 53 patients at a median of 19.5 months after IMRT completion. Of these 8 patients, 7 demonstrated initial nodular enhancement outside the conformal field, and 7 patients died. Conclusion Magnetic resonance imaging changes can occur in the posterior fossa of children treated with IMRT for medulloblastoma. In our experience, these transient changes occur at a characteristic time and location after RT, allowing them to be distinguished from leptomeningeal disease.

Background: Pediatric glioblastoma (GBM) is highly aggressive and development of novel therapy is needed. Aurora A kinase is critical for mitosis and its overexpression results in malignant transformation of normal cells. MLN8237 (Alisertib) is the first orally available reversible selective inhibitor of the Aurora A serine/threonine kinase. We investigated the effects of MLN8237 on glioma stem cell proliferation and animal survival, as well as the effects on clinically-proven therapy resistant GBM cells. Methods: Levels of Aurora A kinase expression were screened in a panel of patient tumor-derived orthotopic xenograft mouse models. Anti-tumor effects was examined by Cell Counting Kit-8 assay in paired monolayer cell lines (in FBS-based media) and neurosphere cultures (in serum-free media containing EGF and bFGF) from two xenograft mouse models, IC-4687GBM (previously untreated) and IC-R0315GBM (established from a therapy-resistant autopsy sample). Therapeutic efficacy was examined in vivo by orally administered MLN8237 (30 mg/kg/day for 12 days) in NOD/SCID mice (n=10 per group) two weeks post intra-cerebral tumor cell implantation. Tumor growth was examined by MRI and histopathological analysis. Results: Overexpression of Aurora A kinase mRNA (4-10 fold over normal control) was observed in our pediatric GBM models. Tumor growth in FBS medium was suppressed in the previously untreated line (4687GBM) but not in the therapy-resistant line (R0315GBM). Cell growth of neurospheres, which are enriched with cancer stem cells, was suppressed in both GBM lines in a time- and dose-dependent manner. In IC-4687GBM, suppression of xenograft tumor growth was confirmed by MRI and histopathological analysis along with significant prolongation of animal survival in the treatment group. In the therapy-resistant model IC-R0315GBM, no significant suppression was observed, which correlates with the in vitro lack of effect on the monolayer cells. Conclusion: We detected high levels Aurora A kinase expression in pediatric GBM models and demonstrated the efficacy of MLN8237 in targeting GBM in vitro and in vivo. Our data in the therapy-resistant model IC-R0315GBM suggests the need for combination treatment in therapy-resistant GBMs. Our results support the evaluation of MLN8237 as a novel agent for pediatric GBMs. Citation Format: Mari Kogiso, Linna Zhang, Lin Qi, Holly B. Lindsay, Frank Y. Lin, Stacey Berg, Xiao-Nan Li, Jodi A. Muscal. Aurora A kinase inhibitor MLN8237 suppresses neurosphere proliferation of pediatric glioblastoma and prolongs animal survival in patient tumor-derived orthotopic xenograft mouse model. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2748. doi:10.1158/1538-7445.AM2014-2748

9522 Background: Vorinostat and bortezomib have demonstrated single agent anti-tumor activity in preclinical models of pediatric solid and CNS tumors, including synergistic anti-tumor activity when the agents are utilized in combination. A pediatric phase I trial was performed to determine the maximal tolerated dose, dose-limiting toxicities (DLTs), and pharmacokinetics (PK) of vorinostat and bortezomib, as well as to assess the impact of bortezomib on NF-κB binding activity and Grp78 protein expression in peripheral blood mononuclear cells (PBMCs). Methods: Oral vorinostat was administered on days 1-5 and 8-12 of a 21 day cycle (starting dose 180 mg/m2/day with dose escalations to 230 and 300 mg/m2/day). Bortezomib (1.3 mg/m2 i.v.) was administered on days 1, 4, 8, and 11. PK and correlative biology studies were performed during cycle 1. Results: 23 eligible patients, 18 male, median age 12 yrs (range, 1-20) were enrolled. 6/23 patients were not fully evaluable for toxicity; 2 did not complete cycle 1, 2...

Purpose: Children with recurrent or refractory tumors often have a poor prognosis. Innovative drug combinations are necessary to increase their disease-free and overall survival. Background: MLN8237 is a reversible inhibitor of the Aurora A serine/threonine kinase that showed excellent activity against several tumor types in the Pediatric Preclinical Testing Program. SAHA is a pan-histone deacetylase (HDAC) inhibitor that has shown pre-clinical activity in leukemia, lymphoma, neuroblastoma, and medulloblastoma. HDAC inhibitors decrease Aurora kinases by a variety of mechanisms, and HDAC inhibitors and Aurora kinase inhibitors disrupt the spindle assembly checkpoint at different points, suggesting that the combination could have increased antitumor activity. Methods: We investigated the combination of MLN8237 and SAHA in pediatric cancer cell lines, Molt-4 (pediatric T-cell ALL), IMR32 (neuroblastoma), and Daoy (medulloblastoma). Cell viability was measured using a modified methyl tetrazolium assay after 72 hours of drug treatment, and the cytotoxicity of the drug combination was analyzed using the universal response surface approach as implemented in ADAPT II modeling. For each single drug experiment, two replicate plates were tested, and for the combination drug experiments, four replicate plates were tested. Results: Our results showed that the single agent IC50 for MLN8237 is 0.02 – 0.04 μM in all cell lines. For SAHA, the single agent IC50 ranged from 0.5 μM for Molt-4 to 2.7 μM for Daoy. Both SAHA and MLN8237 inhibited cell survival in a concentration-dependent fashion. Treatment with SAHA resulted in nearly complete inhibition of cell growth in Molt-4 and IMR32 cells at concentrations > 1 μM and 80% inhibition of Daoy cell growth at the maximum concentration of 10 μM, which is well above the clinically relevant concentration range. Maximum inhibition of cell growth in all three lines occurred with 0.05-0.5 μM MLN8237. At concentrations of MLN8237 exceeding approximately 1 μM, there was a paradoxical increase in viability signal in all three lines, most pronounced for Daoy. This may be explained by inhibition of Aurora B kinase which occurs at higher MLN8237 concentrations. Aurora B inhibition leads to metabolically active multinucleated cells. The combination of MLN8237 plus SAHA showed additive cytotoxicity in all three cell lines and nearly abrogated the survival noted at high single-agent MLN8237 concentrations. Conclusion: These results provide important preclinical support for the development of future clinical studies of MLN8237and SAHA. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5359. doi:10.1158/1538-7445.AM2011-5359