Previous studies have implicated DTNBP1 as a schizophrenia susceptibility gene and its encoded protein, dysbindin, as a potential regulator of synaptic vesicle physiology. In this work, we found that endogenous levels of the dysbindin protein in mouse brain are developmentally regulated, with higher levels observed during embryonic and early postnatal ages than in young adulthood. We obtained biochemical evidence indicating that the bulk of dysbindin from brain exists as a stable component of biogenesis of lysosome-related organelles complex-1 (BLOC-1), a multi-subunit protein complex involved in intracellular membrane trafficking and organelle biogenesis. Selective biochemical interaction between brain BLOC-1 and a few members of the SNARE superfamily of proteins that control membrane fusion, including SNAP-25 and syntaxin 13, was demonstrated. Futhermore, primary hippocampal neurons deficient in BLOC-1 displayed neurite outgrowth defects. Taken together, these observations suggest a novel role for the dysbindin-containing complex, BLOC-1, in neurodevelopment, and provide a framework for considering potential effects of allelic variants in DTNBP1 – or in other genes encoding BLOC-1 subunits – in the context of the developmental model of schizophrenia pathogenesis.

Purpose Previous studies regarding the influence of weight on event-free survival (EFS) and treatment-related toxicity (TRT) in childhood acute lymphoblastic leukemia (ALL) considered only weight at diagnosis. Inasmuch as weight varies substantially over treatment, we hypothesized its impact on EFS is instead determined by cumulative time spent at an extreme weight during therapy and on TRT by weight at the time of toxicity. Patients and Methods In a cohort of 2,008 children treated for high-risk ALL in Children's Oncology Group study CCG-1961, we determined the effect on EFS of cumulative time receiving therapy at an extreme weight (either obese or underweight) between end of induction and start of maintenance therapy. We also evaluated the association between weight category and incidence and patterns of TRT during 13,946 treatment courses. Results Being obese or underweight at diagnosis and for ≥ 50% of the time between end of induction and start of maintenance therapy resulted in inferior EFS (hazard ratios, 1.43 and 2.30, respectively; global P < .001). Normalization of weight during that period resulted in mitigation of this risk comparable to never being obese or underweight. Obese or underweight status at start of each treatment course was significantly associated with specific patterns of TRT. Conclusion Influence of weight extremes on EFS and TRT is not set at diagnosis as previously reported but is moderated by subsequent weight status during intensive postinduction treatment phases. These observations suggest that weight is a potentially addressable risk factor to improve EFS and morbidity in pediatric ALL.

Therapy of relapsed pediatric acute lymphoblastic leukemia (ALL) is hampered by low remission rates and high toxicity, especially in second and subsequent relapses. Our phase 1 study, T2005-003, showed that the combination of bortezomib with vincristine, dexamethasone, pegylated asparaginase, and doxorubicin had acceptable toxicity. We report the phase 2 expansion of this combination in patients with relapsed ALL who failed 2-3 previous regimens. Twenty-two patients with relapsed ALL were treated with bortezomib combined with this regimen; their ages ranged from 1 to 22 years, and they had either B-precursor ALL (n ‫؍‬ 20) or T-cell ALL (n ‫؍‬ 2). Grade 3 peripheral neuropathy developed in 2 (9%) patients. After 3 patients died from bacterial infections, treatment with vancomycin, levofloxacin, and voriconazole prophylaxis resulted in no further infectious mortality in the last 6 patients. Fourteen patients achieved complete remission (CR), and 2 achieved CR without platelet recovery, for an overall 73% response rate, meeting predefined criteria allowing for early closure. B-precursor patients faired best,

Cancer-associated fibroblasts (CAF) have been suggested to originate from mesenchymal stromal cells (MSC), but their relationship to MSC is not clear. Here we have isolated from primary human neuroblastoma (NB) tumors a population of αFAP- and FSP-1-expressing CAF that share phenotypic and functional characteristics with bone marrow-derived MSC (BM-MSC). Analysis of human NB tumors also confirmed the presence of αFAP- and FSP-1-positive cells in the tumor stroma, and their presence correlated with that of M2 tumor-associated macrophages. These cells (designated CAF-MSC) enhanced in vitro NB cell proliferation, survival, and resistance to chemotherapy and stimulated NB tumor engraftment and growth in immunodeficient mice, indicating an effect independent of the immune system. The pro-tumorigenic activity of MSC in vitro and in xenografted mice was dependent on the co-activation of JAK2/STAT3 and MEK/ERK1/2 in NB cells. In a mouse model of orthotopically implanted NB cells, inhibition of JAK2/STAT3 and MEK/ERK/1/2 by ruxolitinib and trametinib potentiated tumor response to etoposide and increased overall survival. These data point to a new type pro-tumorigenic CAF in the tumor microenvironment (TME) of NB and to STAT3 and ERK1/2 as mediators of their activity.

Purpose Immunotherapy of high-risk neuroblastoma using the anti-GD2 antibody dinutuximab induces antibody-dependent cell-mediated cytotoxicity (ADCC). Galunisertib, an inhibitor of TGFβR1, was examined for its ability to enhance the efficacy of dinutuximab in combination with human ex vivo activated NK (aNK) cells against neuroblastoma. Experimental Design TGFB1 and TGFBR1 mRNA expression was determined for 249 primary neuroblastoma tumors by microarray analysis. The ability of galunisertib to inhibit SMAD activity induced by neuroblastoma patient blood and bone marrow plasmas in neuroblastoma cells was tested. The impact of galunisertib on TGFβ1-induced inhibition of aNK cytotoxicity and ADCC in vitro and on anti-neuroblastoma activity in NSG mice was determined. Results Neuroblastomas express TGFB1 and TGFBR1 mRNA. Galunisertib suppressed SMAD activation in neuroblastoma cells induced by exogenous TGFβ1 or by patient blood and bone marrow plasma, and suppressed SMAD2 phosphorylation in human neuroblastoma cells growing in NSG mice. In NK cells treated in vitro with exogenous TGFβ1, galunisertib suppressed SMAD2 phosphorylation and restored the expression of DNAM-1, NKp30, and NKG2D cytotoxicity receptors, TRAIL death ligand, the release of perforin and granzyme A, and the direct cytotoxicity and ADCC of aNK cells against NB cells. Addition of galunisertib to adoptive cell therapy with aNK cells plus dinutuximab reduced tumor growth and increased survival of mice injected with two neuroblastoma cell lines or a patient-derived xenograft. Conclusion Galunisertib suppresses activation of SMAD2 in neuroblastomas and aNK cells, restores NK cytotoxic mechanisms, and increases the efficacy of dinutuximab with aNK cells against neuroblastoma tumors.

BACKGROUND Poor accrual to cancer clinical trials may contribute to the lower improvement in survival observed for adolescents and young adults (AYAs) (those aged 15‐39 years) with cancer. This has been difficult to quantify without reliable mechanisms to link incident cases with study enrollments. Using unique resources available at their National Cancer Institute‐designated comprehensive cancer center, the authors compared the percentage of AYAs, children, and older adults enrolled onto cancer clinical trials and determined predictors of enrollment. METHODS Patients diagnosed with cancer from January 2008 through December 2012 at 1 pediatric and 2 adult University of Southern California hospitals were identified through the California Cancer Registry and individually linked to institutional trial enrollment databases. The availability of clinical trials was assessed. RESULTS Across the center, the enrollment percentage for AYAs (6%) was equal to that of older adults (6%), but was less than that for children (22%) (P < .01). Within the children's hospital, the AYA enrollment percentage was also less than that for children (15% vs 23%, respectively; P<.01). On multivariate analysis, diagnosis and site of care were found to be predictive of AYA enrollment onto therapeutic and nontherapeutic studies. Hispanic and Asian/Pacific Islander individuals were more likely to enroll onto nontherapeutic studies compared with non‐Hispanic whites, but no racial/ethnic difference was observed for therapeutic studies. CONCLUSIONS In the current study, the percentages of AYAs and older adults enrolled onto therapeutic trials were low but similar. Diagnosis, site of care, and race/ethnicity appear to be predictive of enrollment. Prospective mechanisms must be instituted to capture reasons for nonenrollment of AYAs and develop corrective interventions. Cancer 2015;121:4398–406. © 2015 American Cancer Society.

The survival of pediatric patients with multiply relapsed and/or refractory (R/R) B-cell acute lymphoblastic leukemia has historically been very poor; however, data are limited in the current era. We conducted a retrospective study to determine the outcome of multiply R/R childhood B-ALL treated at 24 TACL institutions between 2005 and 2013. Patient information, treatment, and response were collected. Prognostic factors influencing the complete remission (CR) rate and event-free survival (EFS) were analyzed. The analytic set included 578 salvage treatment attempts among 325 patients. CR rates (mean ± SE) were 51 ± 4% for patients with bone marrow R/R B-ALL who underwent a second salvage attempt, 37 ± 6% for a third attempt, and 31 ± 6% for the fourth through eighth attempts combined. For patients achieving a CR after their second, third, and fourth through eighth attempts, the 2 year EFS was 41 ± 6%, 13 ± 7%, and 27 ± 13% respectively. Our results showed slight improvement when compared to previous studies. This is the largest and most recent study to date that evaluates the outcome of this patient population. Our data will provide detailed reference for the evaluation of new agents being developed for childhood B-ALL.

Purpose Alisertib is an oral Aurora A kinase inhibitor with preclinical activity in neuroblastoma. Irinotecan and temozolomide have activity in patients with advanced neuroblastoma. The goal of this phase I study was to determine the maximum tolerated dose (MTD) of alisertib with irinotecan and temozolomide in this population. Patients and Methods Patients age 1 to 30 years with relapsed or refractory neuroblastoma were eligible. Patients received alisertib tablets at dose levels of 45, 60, and 80 mg/m2 per day on days 1 to 7 along with irinotecan 50 mg/m2 intravenously and temozolomide 100 mg/m2 orally on days 1 to 5. Dose escalation of alisertib followed the rolling six design. Samples for pharmacokinetic and pharmacogenomic testing were obtained. Results Twenty-three patients enrolled, and 22 were eligible and evaluable for dose escalation. A total of 244 courses were administered. The MTD for alisertib was 60 mg/m2, with mandatory myeloid growth factor support and cephalosporin prophylaxis for diarrhea. Thrombocytopenia and neutropenia of any grade were seen in the majority of courses (84% and 69%, respectively). Diarrhea in 55% of courses and nausea in 54% of courses were the most common nonhematologic toxicities. The overall response rate was 31.8%, with a 50% response rate observed at the MTD. The median number of courses per patient was eight (range, two to 32). Progression-free survival rate at 2 years was 52.4%. Pharmacokinetic testing did not show evidence of drug-drug interaction between irinotecan and alisertib. Conclusion Alisertib 60 mg/m2 per dose for 7 days is tolerable with a standard irinotecan and temozolomide backbone and has promising response and progression-free survival rates. A phase II trial of this regimen is ongoing.