Interleukin 7 signaling in dendritic cells regulates the homeostatic proliferation and niche size of CD4+ T cells.

Interleukin 7 (IL-7) and T cell antigen receptor signals have been proposed to be the main drivers of homeostatic T cell proliferation. However, it is not known why CD4(+) T cells undergo less-efficient homeostatic proliferation than CD8(+) T cells do. Here we show that systemic IL-7 concentrations increased during lymphopenia because of diminished use of IL-7 but that IL-7 signaling on IL-7 receptor-alpha-positive (IL-7Ralpha(+)) dendritic cells (DCs) in lymphopenic settings paradoxically diminished the homeostatic proliferation of CD4(+) T cells. This effect was mediated at least in part by IL-7-mediated downregulation of the expression of major histocompatibility complex class II on IL-7Ralpha(+) DCs. Our results indicate that IL-7Ralpha(+) DCs are regulators of the peripheral CD4(+) T cell niche and that IL-7 signals in DCs prevent uncontrolled CD4(+) T cell population expansion in vivo.

Nivolumab in children and young adults with relapsed or refractory solid tumours or lymphoma (ADVL1412): a multicentre, open-label, single-arm, phase 1-2 trial.

BACKGROUND: Immune checkpoint inhibitors targeting PD-1 have shown clinical benefit in adults with cancer, but data on these drugs in children are scarce. We did a phase 1-2 study of nivolumab, a PD-1 blocking monoclonal antibody, to determine its safety, pharmacokinetics, and antitumour activity in children and young adults with recurrent or refractory non-CNS solid tumours or lymphoma. METHODS: We did a multicentre, open-label, single-arm, dose-confirmation and dose-expansion, phase 1-2 trial in 23 hospitals in the USA. Eligible patients for part A (dose-confirmation phase) of the study were aged 1-18 years with solid tumours with measurable or evaluable disease (by Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1) regardless of histology. Eligible patients for part B (dose-expansion phase) were aged 1-30 years with measurable disease (by RECIST criteria) in the following disease cohorts: rhabdomyosarcoma, Ewing sarcoma, osteosarcoma, neuroblastoma, Hodgkin lymphoma, non-Hodgkin lymphoma, and melanoma. Patients in part A and were given nivolumab 3 mg/kg intravenously over 60 min on days 1 and 15 of a 28-day cycle in a rolling 6 study design with de-escalation upon dose-limiting toxicities to establish the recommended phase 2 dose. Patients in part B were given the recommended phase 2 dose. The primary outcomes were the tolerability, systemic exposure, maximum tolerated dose, and the antitumour activity of nivolumab at the adult recommended dose in children and young adults. This trial is registered with ClinicalTrials.gov, NCT02304458, with follow-up ongoing and is closed to new participants. FINDINGS: 85 patients were enrolled between Feb 22, 2015, and Dec 31, 2018, and 75 patients were fully evaluable for toxicity. Median follow-up was 30 days (IQR 27-83). In part A, 13 patients were enrolled and 12 were evaluable for toxicity. There were no dose de-escalations or dose-limiting toxicities and nivolumab 3 mg/kg was confirmed as the paediatric recommended phase 2. 72 patients were enrolled in part B and 63 were evaluable for toxicity. Five (7%) patients in part B had dose-limiting toxicities. The most common overall toxicity was anaemia (35 [47%] of 75 patients; five patients had grade 3 or grade 4) and non-haematological toxicity was fatigue (28 [37%] patients; none had grade 3 or grade 4). Responses were observed in patients with lymphoma (three [30%] of ten with Hodgkin lymphoma and one [10%] of ten with non-Hodgkin lymphoma; all responders had PD-L1 expression). Objective responses were not observed in other tumour types. INTERPRETATION: Nivolumab was safe and well tolerated in children and young adults and showed clinical activity in lymphoma. Nivolumab showed no significant single-agent activity in the common paediatric solid tumours. This study defines the recommended phase 2 dose and establishes a favourable safety profile for nivolumab in children and young adults, which can serve as the basis for its potential study in combinatorial regimens for childhood cancer. FUNDING: Bristol-Myers Squibb, Children's Oncology Group, National Institutes of Health, Cookies for Kids Cancer Foundation.

Assessment of programmed death-ligand 1 expression and tumor-associated immune cells in pediatric cancer tissues.

BACKGROUND: Programmed death 1 (PD-1) signaling in the tumor microenvironment dampens immune responses to cancer, and blocking this axis induces antitumor effects in several malignancies. Clinical studies of PD-1 blockade are only now being initiated in pediatric patients, and little is known regarding programmed death-ligand 1 (PD-L1) expression in common childhood cancers. The authors characterized PD-L1 expression and tumor-associated immune cells (TAICs) (lymphocytes and macrophages) in common pediatric cancers. METHODS: Whole slide sections and tissue microarrays were evaluated by immunohistochemistry for PD-L1 expression and for the presence of TAICs. TAICs were also screened for PD-L1 expression. RESULTS: Thirty-nine of 451 evaluable tumors (9%) expressed PD-L1 in at least 1% of tumor cells. The highest frequency histotypes comprised Burkitt lymphoma (80%; 8 of 10 tumors), glioblastoma multiforme (36%; 5 of 14 tumors), and neuroblastoma (14%; 17 of 118 tumors). PD-L1 staining was associated with inferior survival among patients with neuroblastoma (P = .004). Seventy-four percent of tumors contained lymphocytes and/or macrophages. Macrophages were significantly more likely to be identified in PD-L1-positive versus PD-L1-negative tumors (P < .001). CONCLUSIONS: A subset of diagnostic pediatric cancers exhibit PD-L1 expression, whereas a much larger fraction demonstrates infiltration with tumor-associated lymphocytes. PD-L1 expression may be a biomarker for poor outcome in neuroblastoma. Further preclinical and clinical investigation will define the predictive nature of PD-L1 expression in childhood cancers both at diagnosis and after exposure to chemoradiotherapy. Cancer 2017;123:3807-3815. © 2017 American Cancer Society.

Acute GVHD in patients receiving IL-15/4-1BBL activated NK cells following T-cell-depleted stem cell transplantation.

Natural killer (NK) cells can enhance engraftment and mediate graft-versus-leukemia following allogeneic hematopoietic stem cell transplantation (HSCT), but the potency of graft-versus-leukemia mediated by naturally reconstituting NK cells following HSCT is limited. Preclinical studies demonstrate that activation of NK cells using interleukin-15 (IL-15) plus 4-1BBL upregulates activating receptor expression and augments killing capacity. In an effort to amplify the beneficial effects of NK cells post-HSCT, we conducted a first-in-human trial of adoptive transfer of donor-derived IL-15/4-1BBL-activated NK cells (aNK-DLI) following HLA-matched, T-cell-depleted (1-2 × 10(4) T cells/kg) nonmyeloablative peripheral blood stem cell transplantation in children and young adults with ultra-high-risk solid tumors. aNK-DLI were CD3(+)-depleted, CD56(+)-selected lymphocytes, cultured for 9 to 11 days with recombinant human IL-15 plus 4-1BBL(+)IL-15Rα(+) artificial antigen-presenting cells. aNK-DLI demonstrated potent killing capacity and displayed high levels of activating receptor expression. Five of 9 transplant recipients experienced acute graft-versus-host disease (GVHD) following aNK-DLI, with grade 4 GVHD observed in 3 subjects. GVHD was more common in matched unrelated donor vs matched sibling donor recipients and was associated with higher donor CD3 chimerism. Given that the T-cell dose was below the threshold required for GVHD in this setting, we conclude that aNK-DLI contributed to the acute GVHD observed, likely by augmenting underlying T-cell alloreactivity. This trial was registered at www.clinicaltrials.gov as #NCT01287104.

Myeloid cells in peripheral blood mononuclear cell concentrates inhibit the expansion of chimeric antigen receptor T cells.

BACKGROUND AIMS: Autologous chimeric antigen receptor (CAR) T-cell therapies have shown promising clinical outcomes, but T-cell yields have been variable. CD19- and GD2-CAR T-cell manufacturing records were reviewed to identify sources of variability. METHODS: CD19-CAR T cells were used to treat 43 patients with acute lymphocytic leukemia or lymphoma and GD2-CAR T cells to treat eight patients with osteosarcoma and three with neuroblastoma. Both types of CAR T cells were manufactured using autologous peripheral blood mononuclear cells (PBMC) concentrates and anti-CD3/CD28 beads for T-cell enrichment and simulation. RESULTS: A comparison of the first 6 GD2- and the first 22 CD19-CAR T-cell products manufactured revealed that GD2-CAR T-cell products contained fewer transduced cells than CD19-CAR T-cell products (147 ± 102 × 10(6) vs 1502 ± 1066 × 10(6); P = 0.0059), and their PBMC concentrates contained more monocytes (31.4 ± 12.4% vs 18.5 ± 13.7%; P = 0.019). Among the first 28 CD19-CAR T-cell products manufactured, four had poor expansion yielding less than 1 × 10(6) transduced T cells per kilogram. When PBMC concentrates from these four patients were compared with the 24 others, PBMC concentrates of poorly expanding products contained greater quantities of monocytes (39.8 ± 12.9% vs. 15.3 ± 10.8%, P = 0.0014). Among the patients whose CD19-CAR T cells expanded poorly, manufacturing for two patients was repeated using cryopreserved PBMC concentrates but incorporating a monocyte depleting plastic adherence step, and an adequate dose of CAR T cells was produced for both patients. CONCLUSIONS: Variability in CAR T-cell expansion is due, at least in part, to the contamination of the starting PBMC concentrates with monocytes.

Vincristine Sulfate Liposomes Injection (VSLI, Marqibo®): Results From a Phase I Study in Children, Adolescents, and Young Adults With Refractory Solid Tumors or Leukemias.

BACKGROUND: Vincristine sulfate liposome injection (VSLI; Marqibo®) is an encapsulated preparation of standard vincristine in sphingomyelin/cholesterol liposomes. Clinical trials in adults have demonstrated safety, tolerability, and activity, leading to Food and Drug Administration (FDA) approval for adults with relapsed acute lymphoblastic leukemia (ALL). Pediatric experience with VSLI is limited. PROCEDURE: This single center, phase I dose escalation study examined the safety, toxicity, maximum tolerated dose, and pharmacokinetics of VSLI administered weekly to pediatric patients age <21 years with relapsed or chemotherapy-refractory solid tumors or leukemia. RESULTS: Twenty-one subjects were treated in total. Median age was 13.3 years (range 2-19). Fourteen subjects completed one 28-day cycle of therapy and five subjects completed more than one cycle. No subject experienced dose-limiting toxicity (DLT) at the first dose level (1.75 mg/m(2) /dose, dose range: 2-3.7 mg). At the second dose level (2.25 mg/m(2) /dose, dose range: 1.3-4.5 mg), one subject had transient dose-limiting grade 4 transaminase elevation, and this dose level was expanded with no additional DLT observed. The second dose level then opened to an expansion phase to evaluate activity in ALL. Clinical activity included minimal residual disease negative complete remission in one subject with ALL and stable disease in nine subjects. Clearance of total vincristine was found to be approximately 100-fold lower in comparison to published data using standard vincristine. CONCLUSIONS: Children tolerate 2.25 mg/m(2) /dose of weekly VSLI (the adult FDA-approved dose) with evidence for clinical activity without dose-limiting neurotoxicity. Future plans include studying VSLI as substitution for standard vincristine with combination chemotherapy in children with ALL.

What do parents want to know when considering autopsy for their child with cancer?

Research has suggested that autopsy in pediatrics is a valued way for parents to better understand and process their child's death, yet physicians often express hesitancy in discussing this topic with parents. To better assist clinicians with initiating discussion about this often sensitive topic, the current study examined bereaved parents' preferences about the timing and content of the autopsy discussion as well as reasons for considering autopsy. This study explored the views of 30 parents who lost a child to a variety of malignancies between 6 months and 6 years ago. Results showed that 36.7% of parents recalled having a discussion about autopsy, and the vast majority of those who did not recall a discussion (89.5%) would have considered an autopsy if it had been discussed. The majority of participants in this study indicated their preference to have the first conversation about autopsy when it becomes clear that cure is no longer possible. Findings suggest that educating parents about the clinical, emotional, and potential research benefits of autopsy and tissue procurement will ultimately help them make informed decisions and understand the importance of autopsy in medical progress. The future research and clinical implications of these findings are discussed.

Positron emission tomography for response assessment in desmoplastic small round cell tumor.

BACKGROUND: Desmoplastic small round cell tumors (DSRCT) typically have a large stromal component and often are extensively disseminated in the peritoneal cavity at diagnosis. These factors contribute to difficulty in quantifying response to chemotherapy using RECIST or WHO criteria. This study compares the overall disease response to chemotherapy by fluorodeoxyglucose-positron emission tomography (FDG-PET) and computed tomography (CT) in patients with DSRCT. METHODS: We conducted a retrospective chart review of 7 patients with DSRCT who were imaged by FDG-PET and CT at diagnosis and after 3 cycles of chemotherapy. Response to chemotherapy was graded according to EORTC metabolic response guidelines and RECIST. RESULTS: All tumors demonstrated some decrease in SUVmax (51%±21%) and longest diameter (23%±8%) with chemotherapy. The best response achieved by FDG-PET was a partial response in 6 patients and by CT was a partial response in 1 patient. Measured response was concordant between the 2 modalities in 2 patients. CONCLUSIONS: In this small series response measurement by FDG-PET did not always correlate with response measurement by CT. A greater decrease in metabolic activity as compared with size was seen in all patients. Further studies are needed to define the role of FDG-PET in assessing early response of DSRCT to chemotherapy.

Brain exposure of the ATM inhibitor AZD1390 in humans-a positron emission tomography study.

BACKGROUND: The protein kinase ataxia telangiectasia mutated (ATM) mediates cellular response to DNA damage induced by radiation. ATM inhibition decreases DNA damage repair in tumor cells and affects tumor growth. AZD1390 is a novel, highly potent, selective ATM inhibitor designed to cross the blood-brain barrier (BBB) and currently evaluated with radiotherapy in a phase I study in patients with brain malignancies. In the present study, PET was used to measure brain exposure of 11C-labeled AZD1390 after intravenous (i.v.) bolus administration in healthy subjects with an intact BBB. METHODS: AZD1390 was radiolabeled with carbon-11 and a microdose (mean injected mass 1.21 µg) was injected in 8 male subjects (21-65 y). The radioactivity concentration of [11C]AZD1390 in brain was measured using a high-resolution PET system. Radioactivity in arterial blood was measured to obtain a metabolite corrected arterial input function for quantitative image analysis. Participants were monitored by laboratory examinations, vital signs, electrocardiogram, adverse events. RESULTS: The brain radioactivity concentration of [11C]AZD1390 was 0.64 SUV (standard uptake value) and reached maximum 1.00% of injected dose at Tmax[brain] of 21 min (time of maximum brain radioactivity concentration) after i.v. injection. The whole brain total distribution volume was 5.20 mL*cm-3. No adverse events related to [11C]AZD1390 were reported. CONCLUSIONS: This study demonstrates that [11C]AZD1390 crosses the intact BBB and supports development of AZD1390 for the treatment of glioblastoma multiforme or other brain malignancies. Moreover, it illustrates the potential of PET microdosing in predicting and guiding dose range and schedule for subsequent clinical studies.

Pediatric PK/PD Phase I Trial of Pexidartinib in Relapsed and Refractory Leukemias and Solid Tumors Including Neurofibromatosis Type I-Related Plexiform Neurofibromas.

PURPOSE: Simultaneously targeting the tumor and tumor microenvironment may hold promise in treating children with refractory solid tumors. Pexidartinib, an oral inhibitor of tyrosine kinases including colony stimulating factor 1 receptor (CSF-1R), KIT, and FLT3, is FDA approved in adults with tenosynovial giant cell tumor. A phase I trial was conducted in pediatric and young adult patients with refractory leukemias or solid tumors including neurofibromatosis type 1-related plexiform neurofibromas. PATIENTS AND METHODS: A rolling six design with dose levels (DL) of 400 mg/m2, 600 mg/m2, and 800 mg/m2 once daily for 28-day cycles (C) was used. Response was assessed at regular intervals. Pharmacokinetics and population pharmacokinetics were analyzed during C1. RESULTS: Twelve patients (4 per DL, 9 evaluable) enrolled on the dose-escalation phase and 4 patients enrolled in the expansion cohort: median (lower, upper quartile) age 16 (14, 16.5) years. No dose-limiting toxicities were observed. Pharmacokinetics appeared linear over three DLs. Pharmacokinetic modeling and simulation determined a weight-based recommended phase II dose (RP2D). Two patients had stable disease and 1 patient with peritoneal mesothelioma (C49+) had a sustained partial response (67% RECIST reduction). Pharmacodynamic markers included a rise in plasma macrophage CSF (MCSF) levels and a decrease in absolute monocyte count. CONCLUSIONS: Pexidartinib in pediatric patients was well tolerated at all DL tested, achieved target inhibition, and resulted in a weight-based RPD2 dose.

Current approach to pediatric soft tissue sarcomas.

The development of a new soft tissue lesion in an otherwise healthy child, adolescent, or young adult can present many challenges for pediatric or medical oncology teams. Although uncommon, the diagnosis of a soft tissue malignancy should always be considered in the differential diagnosis of persistent pain, even if no mass is palpable. The definitive diagnosis and treatment of a soft tissue mass is aided by timely scans, appropriate biopsy for anatomic and molecular pathology, and a treatment approach guided by the specific diagnosis. Because pediatric soft tissue sarcomas are rare, cooperative groups play a crucial role in defining the standard of care through retrospective series and well-designed prospective clinical trials. Enrollment of newly diagnosed patients in clinical studies should be encouraged in order to continue to improve outcomes and understanding of these rare tumors. This review focuses on the current recommendations for management of sarcomas that typically occur in the soft tissues of pediatric and young adult patients.

Irinotecan and temozolomide for Ewing sarcoma: the Memorial Sloan-Kettering experience.

BACKGROUND: The prognosis for recurrent/progressive Ewing sarcoma (ES) remains poor. Pre-clinical, adult phase I and II trials have demonstrated the combination of irinotecan and temozolomide to have schedule-dependent synergy and significant antitumor activity. A pediatric phase I trial has shown this regimen to be safe and active in advanced ES. PROCEDURE: We conducted a retrospective chart review to identify patients with recurrent/progressive ES treated with irinotecan [20 mg/m(2)/day x 5(x2)] and temozolomide (100 mg/m(2)/day x 5) in our institution. The best response achieved, time to progression (TTP), and associated toxicities were recorded. RESULTS: Twenty patients received a total of 154 cycles of therapy. Of 19 evaluable patients, there were 5 complete and 7 partial responses (a 63% overall objective response). Median TTP for 20 evaluable patients with recurrent/progressive ES was 8.3 months; for the subset of 14 patients with recurrent ES, it was 16.2 months. Median TTP was better for patients who sustained a 2-year first remission than for those who relapsed < 24 months from diagnosis and for patients with primary localized vs. metastatic disease. Significant toxicities included grade 3 diarrhea (7 cycles), grade 3 colitis (1 cycle), grade 3 pneumonitis in one patient receiving concurrent whole-lung RT, grade 3-4 neutropenia (19 cycles), and grade 3-4 thrombocytopenia (16 cycles). CONCLUSIONS: Irinotecan and temozolomide is a well-tolerated and active regimen for recurrent/progressive ES. Prospective trials are necessary to define the role of this regimen in newly diagnosed ES.

Antitumor Activity Associated with Prolonged Persistence of Adoptively Transferred NY-ESO-1 c259T Cells in Synovial Sarcoma.

We evaluated the safety and activity of autologous T cells expressing NY-ESO-1c259, an affinity-enhanced T-cell receptor (TCR) recognizing an HLA-A2-restricted NY-ESO-1/LAGE1a-derived peptide, in patients with metastatic synovial sarcoma (NY-ESO-1c259T cells). Confirmed antitumor responses occurred in 50% of patients (6/12) and were characterized by tumor shrinkage over several months. Circulating NY-ESO-1c259T cells were present postinfusion in all patients and persisted for at least 6 months in all responders. Most of the infused NY-ESO-1c259T cells exhibited an effector memory phenotype following ex vivo expansion, but the persisting pools comprised largely central memory and stem-cell memory subsets, which remained polyfunctional and showed no evidence of T-cell exhaustion despite persistent tumor burdens. Next-generation sequencing of endogenous TCRs in CD8+ NY-ESO-1c259T cells revealed clonal diversity without contraction over time. These data suggest that regenerative pools of NY-ESO-1c259T cells produced a continuing supply of effector cells to mediate sustained, clinically meaningful antitumor effects.Significance: Metastatic synovial sarcoma is incurable with standard therapy. We employed engineered T cells targeting NY-ESO-1, and the data suggest that robust, self-regenerating pools of CD8+ NY-ESO-1c259T cells produce a continuing supply of effector cells over several months that mediate clinically meaningful antitumor effects despite prolonged exposure to antigen. Cancer Discov; 8(8); 944-57. ©2018 AACR.See related commentary by Keung and Tawbi, p. 914This article is highlighted in the In This Issue feature, p. 899.

Potential use of imatinib in Ewing's Sarcoma: evidence for in vitro and in vivo activity.

BACKGROUND: Ewing's sarcoma cells express c-kit, a receptor tyrosine kinase, and its ligand, stem cell factor (SCF), creating a potential autocrine loop that may promote tumor survival. We thus examined whether the specific tyrosine kinase inhibitor imatinib mesylate (hereafter imatinib; formerly STI571) could inhibit the proliferation of Ewing's sarcoma cells in vitro and in vivo. METHODS: The effect of imatinib on c-kit expression and phosphorylation in Ewing's sarcoma cells was examined by immunoblotting. The effect of imatinib on cell growth and apoptosis was examined with an MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] assay and with a morphologic test and Annexin V staining, respectively. The effect of imatinib oral therapy (every 12 hours for 5-7 days) on primary tumor growth was assessed in Ewing's sarcoma xenografts in SCID/bg mice (5 or 10 mice per group). RESULTS: All Ewing's sarcoma cell lines tested were sensitive to imatinib-mediated apoptosis with a concentration inhibiting growth by 50% (IC50) of 10-12 micro M. Imatinib inhibited SCF-mediated c-kit phosphorylation (IC50 = 0.1-0.5 microM). In the xenograft model, imatinib treatment resulted in the regression or control of primary Ewing's sarcomas. After 6 days of treatment, the mean lower extremity volume including xenograft tumor was 3744 mm3 (95% confidence interval [CI] = 3050 to 4437 mm3), 1442 mm3 (95% CI = 931 to 1758 mm3), and 346 mm3 (95% CI = 131 to 622 mm3) in mice treated with carrier alone or with imatinib at 50 mg/kg or at 100 mg/kg, respectively. CONCLUSIONS: Imatinib interferes with growth of all Ewing's sarcoma cell lines tested in vitro and in vivo. Targeted inhibition of tyrosine kinase-dependent autocrine loops, therefore, may be a viable therapeutic strategy for Ewing's sarcoma.

Interferon gamma enhances the effectiveness of tumor necrosis factor-related apoptosis-inducing ligand receptor agonists in a xenograft model of Ewing's sarcoma.

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces selective apoptosis in a variety of tumors, including most cell lines derived from Ewing's sarcoma family of tumors, an aggressive sarcoma that afflicts children and young adults. To determine the in vivo efficacy of TRAIL receptor agonists in Ewing's sarcoma family of tumors, mice with orthotopic xenografts were treated with anti-TRAIL-R2 monoclonal antibody or TRAIL/Apo2L in a model that can identify effects on both primary tumors and metastases. Administration of either agonist slowed tumor growth in 60% of animals and induced durable remissions in 11 to 19% but did not alter the incidence of metastatic disease. Response rates were not improved by concurrent doxorubicin treatment. Cells recovered from both TRAIL receptor agonist-treated and nontreated tumors were found to be resistant to TRAIL-induced death in vitro unless pretreated with interferon (IFN) gamma. This resistance coincided with a selective down-regulation of TRAIL receptor expression on tumor cells. In vivo treatment with IFNgamma increased tumor expression of TRAIL receptors and caspase 8, but did not increase the antitumor effect of TRAIL receptor agonists on primary tumors. However, IFNgamma treatment alone or in combination with a TRAIL receptor agonist significantly decreased the incidence of metastatic disease and the combination of TRAIL receptor agonist therapy with IFNgamma-mediated impressive effects on both primary tumors and metastatic disease. These data demonstrate that in vivo growth favors TRAIL resistance but that TRAIL receptor agonists are active in Ewing's sarcoma family of tumors and that the combination of TRAIL receptor agonists with IFNgamma is a potent regimen in this disease capable of controlling both primary and metastatic tumors.

Induction of caspase 8 by interferon gamma renders some neuroblastoma (NB) cells sensitive to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) but reveals that a lack of membrane TR1/TR2 also contributes to TRAIL resistance in NB.

The resistance of neuroblastoma (NB) cells to tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis has been attributed to a lack of caspase 8 expression. Here we demonstrate a clinically applicable molecular targeting strategy that not only increases caspase 8 expression ex vivo in NB cell lines but also in the tumor tissues of NB patients receiving IFN-gamma treatment. We identify the functional caspase 8 promoter, which is different from the methylated region reported previously, and show promoter activity is up-regulated by IFN-gamma through a IFN-gamma activation site-containing region. IFN-gamma also induces TRAIL expression in NB cell lines. However, the IFN-gamma restoration of caspase 8 in some NB cells revealed persistent TRAIL resistance in most NB cell lines examined. This additional lesion in the TRAIL path is because of a loss of cell membrane TRAIL receptors (TR1/TR2) not only in cell lines but in most of the NB tumor tissues evaluated. Restoration of TR2 expression by transfection enhances IFN-gamma-induced TRAIL sensitivity. Furthermore, we have found that we can improve TRAIL sensitivity in NB by reconstituting caspase 8 with IFN-gamma and TR2 with chemotherapeutic agents.

Adjuvant Immunotherapy to Improve Outcome in High-Risk Pediatric Sarcomas.

PURPOSE: Patients with metastatic or relapsed pediatric sarcomas receive cytotoxic regimens that induce high remission rates associated with profound lymphocyte depletion, but ultimately few survive long term. We administered adjuvant immunotherapy to patients with metastatic and recurrent pediatric sarcomas in an effort to improve outcomes. EXPERIMENTAL DESIGN: Mononuclear cells were collected via apheresis, and tumor lysate was acquired via percutaneous biopsy at enrollment. Participants received standard antineoplastic therapy, followed by autologous lymphocytes, tumor lysate/keyhole limpet hemocyanin-pulsed dendritic cell vaccinations ± recombinant human IL7. Primary outcomes were toxicity and vaccine responses. Secondary outcomes were immune reconstitution, event-free survival, and overall survival (OS). RESULTS: Forty-three patients enrolled and 29 received immunotherapy. The regimen was well tolerated. Intent-to-treat analysis demonstrated 5-year OS of 51% with significant differences based upon histologic group (63% vs. 0% for Ewing/rhabdomyosarcoma vs. other sarcomas) and response to standard therapy (74% no residual disease vs. 0% residual disease). Five-year intent-to-treat OS of patients with newly diagnosed metastatic Ewing/rhabdomyosarcoma was 77%, higher than previously reported in this population and higher than observed in a similar group treated with an earlier adjuvant immunotherapy regimen (25% 5-year OS). T-cell responses to autologous tumor lysate were identified in 62% of immunotherapy recipients, and survival was higher in those patients (73% 5-year OS with vs. 37% without immune response, P = 0.017). Immune reconstitution, measured by CD4 count recovery, was significantly enhanced in subjects treated with recombinant human IL7. CONCLUSIONS: Adjuvant immunotherapy may improve survival in patients with metastatic pediatric sarcoma. Clin Cancer Res; 22(13); 3182-91. ©2016 AACR.

Phase I Clinical Trial of Ipilimumab in Pediatric Patients with Advanced Solid Tumors.

PURPOSE: Ipilimumab is a first-in-class immune checkpoint inhibitor approved for treatment of metastatic melanoma but not studied in children until this phase I protocol. EXPERIMENTAL DESIGN: This study examined safety, pharmacokinetics, and immunogenicity, and immune correlates of ipilimumab administered to subjects ≤21 years old with recurrent or progressive solid tumors. Dose escalation cohorts received 1, 3, 5, or 10 mg/m(2) intravenously every 3 weeks in a 3 + 3 design. Response was assessed after 6 weeks and 12 weeks, and then every 3 months. Treatment was continued until disease progression or unacceptable toxicity. RESULTS: Thirty-three patients received 72 doses of ipilimumab. Patients enrolled had melanoma (n = 12), sarcoma (n = 17), or other refractory solid tumors (n = 4). Immune-related adverse events included pancreatitis, pneumonitis, colitis, endocrinopathies, and transaminitis with dose-limiting toxicities observed at 5 and 10 mg/kg dose levels. Pharmacokinetics revealed a half-life of 8 to 15 days. At day 21, subjects had increased levels of cycling T cells, but no change in regulatory T-cell populations. Six subjects had confirmed stable disease for 4 to 10 cycles (melanoma, osteosarcoma, clear cell sarcoma, and synovial sarcoma). CONCLUSIONS: Ipilimumab was safely administered to pediatric patients using management algorithms for immune-related toxicities. The spectrum of immune-related adverse events is similar to those described in adults; however, many of the pediatric toxicities were evident after a single dose. Although no objective tumor regressions were observed with ipilimumab as a single agent, subjects with immune-related toxicities had an increased overall survival compared with those who showed no evidence of breaking tolerance.

MultiDimensional ClinOmics for Precision Therapy of Children and Adolescent Young Adults with Relapsed and Refractory Cancer: A Report from the Center for Cancer Research.

PURPOSE: We undertook a multidimensional clinical genomics study of children and adolescent young adults with relapsed and refractory cancers to determine the feasibility of genome-guided precision therapy. EXPERIMENTAL DESIGN: Patients with non-central nervous system solid tumors underwent a combination of whole exome sequencing (WES), whole transcriptome sequencing (WTS), and high-density single-nucleotide polymorphism array analysis of the tumor, with WES of matched germline DNA. Clinically actionable alterations were identified as a reportable germline mutation, a diagnosis change, or a somatic event (including a single nucleotide variant, an indel, an amplification, a deletion, or a fusion gene), which could be targeted with drugs in existing clinical trials or with FDA-approved drugs. RESULTS: Fifty-nine patients in 20 diagnostic categories were enrolled from 2010 to 2014. Ages ranged from 7 months to 25 years old. Seventy-three percent of the patients had prior chemotherapy, and the tumors from these patients with relapsed or refractory cancers had a higher mutational burden than that reported in the literature. Thirty patients (51% of total) had clinically actionable mutations, of which 24 (41%) had a mutation that was currently targetable in a clinical trial setting, 4 patients (7%) had a change in diagnosis, and 7 patients (12%) had a reportable germline mutation. CONCLUSIONS: We found a remarkably high number of clinically actionable mutations in 51% of the patients, and 12% with significant germline mutations. We demonstrated the clinical feasibility of next-generation sequencing in a diverse population of relapsed and refractory pediatric solid tumors. Clin Cancer Res; 22(15); 3810-20. ©2016 AACR.