PRL2 phosphatase enhances oncogenic FLT3 signaling via dephosphorylation of the E3 ubiquitin ligase CBL at tyrosine 371.

Acute myeloid leukemia (AML) is an aggressive blood cancer with poor prognosis. FMS-like tyrosine kinase receptor-3 (FLT3) is one of the major oncogenic receptor tyrosine kinases aberrantly activated in AML. Although protein tyrosine phosphatase PRL2 is highly expressed in some subtypes of AML compared with normal human hematopoietic stem and progenitor cells, the mechanisms by which PRL2 promotes leukemogenesis are largely unknown. We discovered that genetic and pharmacological inhibition of PRL2 significantly reduce the burden of FLT3-internal tandem duplications-driven leukemia and extend the survival of leukemic mice. Furthermore, we found that PRL2 enhances oncogenic FLT3 signaling in leukemia cells, promoting their proliferation and survival. Mechanistically, PRL2 dephosphorylates the E3 ubiquitin ligase CBL at tyrosine 371 and attenuates CBL-mediated ubiquitination and degradation of FLT3, leading to enhanced FLT3 signaling in leukemia cells. Thus, our study reveals that PRL2 enhances oncogenic FLT3 signaling in leukemia cells through dephosphorylation of CBL and will likely establish PRL2 as a novel druggable target for AML.

A phase 1 trial utilizing a pharmacokinetic endpoint to determine the optimal dose of ramucirumab in children and adolescents with relapsed or refractory solid tumors, including central nervous system tumors.

BACKGROUND: Ramucirumab is a monoclonal antibody that binds the extracellular domain of vascular endothelial growth factor receptor (VEGFR-2) and prevents binding of VEGF ligands. Based on population pharmacokinetic (PK) analysis and correlation with efficacy in adults, a target steady state trough concentration (Css,min ) ≥ 50 µg/mL was established. PROCEDURES: This phase 1 trial (ADVL1416) used a rolling six design and a PK primary endpoint to define the recommended phase 2 dose (RP2D) of ramucirumab in children with recurrent/refractory solid tumors. Two dose levels (DL) were planned (DL1: 8 mg/kg, DL2: 12 mg/kg administered intravenously [IV] every 2 weeks). Toxicity during the initial 6 weeks was used to assess maximum tolerated dose (MTD). Cycle 1 Day 42 trough (Cmin ) ≥ 50 µg/mL was the target concentration for the PK endpoint. At the RP2D, cohorts for PK expansion and children with central nervous tumors were planned. RESULTS: Twenty-nine patients were enrolled; 28 were eligible; median age [range] = 13.5 [1-21] years; 22 were evaluable for the PK endpoint. Dose-limiting proteinuria occurred at both DLs; however, the MTD was not exceeded. At DL2 (12 mg/kg), the median Day 42 Cmin (n = 16) was 87.8 µg/mL; 15 of 16 patients achieved a Cmin  ≥ 50 µg/mL. CONCLUSION: Ramucirumab was well tolerated in children and adolescents with solid tumors. The RP2D for ramucirumab was 12 mg/kg IV every 2 weeks. This trial demonstrates the feasibility of incorporating a primary PK endpoint to determine dose escalation and the RP2D in children. Studies of ramucirumab in children with selected solid tumors are ongoing.

Evidence for BCR/ABL1-positive T-cell acute lymphoblastic leukemia arising in an early lymphoid progenitor cell.

BCR-ABL1-positive leukemias have historically been classified as either chronic myelogenous leukemia or Ph+ acute lymphoblastic leukemia. Recent analyses suggest there may be a wider range of subtypes. We report a patient with BCR-ABL1 fusion positive T-cell ALL with a previously undescribed cell distribution of the fusion gene. The examination of sorted cells by fluorescence in situ hybridization showed the BCR-ABL1 fusion in the malignant T cells and a subpopulation of the nonmalignant B cells, but not nonmalignant T cells or myeloid or CD34+ progenitor cells providing evidence that the fusion may have occurred in an early lymphoid progenitor.

Fever and neutropenia hospital discharges in children with cancer: A 2012 update.

Fever and neutropenia (FN) is a common precipitant for hospitalization among children with cancer, but hospital utilization trends are not well described. This study describes national trends for hospital discharges for FN among children with cancer for the year 2012, compared with the authors' previous analysis from 2009. Data were analyzed from the Kids' Inpatient Database (KID), an all-payer US hospital database, for 2012. Pediatric patients with cancer who had a discharge for FN were identified using age ≤19 years, urgent or emergent admit type, nontransferred, and a combination of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes for fever and neutropenia. The authors evaluated factors associated with a "short length of stay" (SLOS). Sampling weights were used to permit national inferences. In 2012, children with cancer accounted for 1.8% of pediatric hospital discharges (n = 120,675), with 12.2% (n = 13,456) of cancer-related discharges meeting FN criteria. Two fifths of FN discharges had a SLOS, which accounted for $91 million (2015 US$) in hospital charges. The majority had no serious infections; most common infections were viral infection (9.6%) or upper respiratory infection (9.6%). Factors significantly associated with SLOS included having a diagnosis of ear infection (odds ratio [OR] = 1.54, 95% confidence interval [CI]: 1.16-2.03), soft tissue sarcoma (OR = 1.47, CI: 1.10-1.95), and Hodgkin lymphoma (OR = 1.51, CI: 1.09-2.10), as compared with not having those diagnoses. SLOS admissions continue to be rarely associated with serious infections, but contribute substantially to the burden of hospitalization for pediatric FN. Implementation of risk stratification schemas to identify patients who meet low-risk criteria may decrease financial burden.

PRL2 Phosphatase Promotes Oncogenic KIT Signaling in Leukemia Cells through Modulating CBL Phosphorylation.

Receptor tyrosine kinase KIT is frequently activated in acute myeloid leukemia (AML). While high PRL2 (PTP4A2) expression is correlated with activation of SCF/KIT signaling in AML, the underlying mechanisms are not fully understood. We discovered that inhibition of PRL2 significantly reduces the burden of oncogenic KIT-driven leukemia and extends leukemic mice survival. PRL2 enhances oncogenic KIT signaling in leukemia cells, promoting their proliferation and survival. We found that PRL2 dephosphorylates CBL at tyrosine 371 and inhibits its activity toward KIT, leading to decreased KIT ubiquitination and enhanced AKT and ERK signaling in leukemia cells. IMPLICATIONS: Our studies uncover a novel mechanism that fine-tunes oncogenic KIT signaling in leukemia cells and will likely identify PRL2 as a novel therapeutic target in AML with KIT mutations.

Imatinib mesylate for plexiform neurofibromas in patients with neurofibromatosis type 1: a phase 2 trial.

BACKGROUND: Plexiform neurofibromas are slow-growing chemoradiotherapy-resistant tumours arising in patients with neurofibromatosis type 1 (NF1). Currently, there are no viable therapeutic options for patients with plexiform neurofibromas that cannot be surgically removed because of their proximity to vital body structures. We undertook an open-label phase 2 trial to test whether treatment with imatinib mesylate can decrease the volume burden of clinically significant plexiform neurofibromas in patients with NF1. METHODS: Eligible patients had to be aged 3-65 years, and to have NF1 and a clinically significant plexiform neurofibroma. Patients were treated with daily oral imatinib mesylate at 220 mg/m(2) twice a day for children and 400 mg twice a day for adults for 6 months. The primary endpoint was a 20% or more reduction in plexiform size by sequential volumetric MRI imaging. Clinical data were analysed on an intention-to-treat basis; a secondary analysis was also done for those patients able to take imatinib mesylate for 6 months. This trial is registered with ClinicalTrials.gov, number NCT01673009. FINDINGS: Six of 36 patients (17%, 95% CI 6-33), enrolled on an intention-to-treat basis, had an objective response to imatinib mesylate, with a 20% or more decrease in tumour volume. Of the 23 patients who received imatinib mesylate for at least 6 months, six (26%, 95% CI 10-48) had a 20% or more decrease in volume of one or more plexiform tumours. The most common adverse events were skin rash (five patients) and oedema with weight gain (six). More serious adverse events included reversible grade 3 neutropenia (two), grade 4 hyperglycaemia (one), and grade 4 increases in aminotransferase concentrations (one). INTERPRETATION: Imatinib mesylate could be used to treat plexiform neurofibromas in patients with NF1. A multi-institutional clinical trial is warranted to confirm these results. FUNDING: Novartis Pharmaceuticals, the Indiana University Simon Cancer Centre, and the Indiana University Herman B Wells Center for Pediatric Research.

A phase 1, first-in-child, multicenter study to evaluate the safety and efficacy of the oncolytic herpes virus talimogene laherparepvec in pediatric patients with advanced solid tumors.

Background: The survival rates for pediatric patients with relapsed and refractory tumors are poor. Successful treatment strategies are currently lacking and there remains an unmet need for novel therapies for these patients. We report here the results of a phase 1 study of talimogene laherparepvec (T-VEC) and explore the safety of this oncolytic immunotherapy for the treatment of pediatric patients with advanced non-central nervous system tumors. Methods: T-VEC was delivered by intralesional injection at 106 plaque-forming units (PFU)/ml on the first day, followed by 108 PFU/ml on the first day of week 4 and every 2 weeks thereafter. The primary objective was to evaluate the safety and tolerability as assessed by the incidence of dose-limiting toxicities (DLTs). Secondary objectives included efficacy indicated by response and survival per modified immune-related response criteria simulating the Response Evaluation Criteria in Solid Tumors (irRC-RECIST). Results: Fifteen patients were enrolled into two cohorts based on age: cohort A1 (n = 13) 12 to ≤21 years old (soft-tissue sarcoma, n = 7; bone sarcoma, n = 3; neuroblastoma, n = 1; nasopharyngeal carcinoma, n = 1; and melanoma, n = 1) and cohort B1 (n = 2) 2 to <12 years old (melanoma, n = 2). Overall, patients received treatment for a median (range) of 5.1 (0.1, 39.4) weeks. No DLTs were observed during the evaluation period. All patients experienced at least one treatment-emergent adverse event (TEAE), and 53.3% of patients reported grade ≥3 TEAEs. Overall, 86.7% of patients reported treatment-related TEAEs. No complete or partial responses were observed, and three patients (20%) overall exhibited stable disease as the best response. Conclusions: T-VEC was tolerable as assessed by the observation of no DLTs. The safety data were consistent with the patients' underlying cancer and the known safety profile of T-VEC from studies in the adult population. No objective responses were observed. Trial Registration: ClinicalTrials.gov: NCT02756845. https://clinicaltrials.gov/ct2/show/NCT02756845.

Parents' Insights into Pediatric Oncology Phase I Clinical Trials: Experiences from Their Child's Participation.

OBJECTIVES: Phase 1 clinical trials are essential in the development of novel therapies for childhood cancers. Children with cancer can participate in phase 1 clinical trials when no known curative therapy remains. Understanding the experiences of children and their families in these clinical trials can help ensure that participation supports the children's and parents' well-being. This article explores the specific aspects of pediatric oncology phase 1 trials that parents found particularly challenging. DATA SOURCES: This qualitative, empirical phenomenology study considered 11 parents' experiences during the time their child with cancer participated in a phase 1 clinical trial. The primary study results were previously reported. This article reports parents' insights into the processes and procedures that occurred as part of participation in a pediatric oncology phase 1 trial. CONCLUSION: Parents' experiences during the phase 1 clinical trials were primarily positive. However, data analysis revealed five aspects of these trials that were challenging for families: learning about clinical trials, being referred to another institution, research-only procedures, adhering to trial requirements, and oral medications. IMPLICATIONS FOR NURSING PRACTICE: Although experiences during phase 1 clinical trials were positive overall, opportunities to enhance children's and parents' experiences warrant attention. Enhancing the education provided to families during recruitment and minimizing the logistical burdens associated with trial requirements through care coordination may alleviate challenges experienced by children and parents.

Population pharmacokinetics of intravenous ondansetron in oncology and surgical patients aged 1-48 months.

PURPOSE: Until recently, ondansetron was approved for the prevention of nausea and vomiting only in patients older than 2 years. However, as the use of ondansetron in patients younger than 2 years had been documented, characterization of ondansetron pharmacokinetics in this younger pediatric age group was warranted. METHODS: The pharmacokinetics of intravenously administered ondansetron were evaluated in oncology and surgical patients aged 1-48 months. Pooled data from 124 patients, including 745 pharmacokinetic samples, were analyzed using nonlinear mixed-effects modeling. RESULTS: Ondansetron pharmacokinetics were described by a two-compartment model. Body-size effects on ondansetron disposition were accounted for via standard allometric relationships, normalized to 10.4 kg. A maturation process with a half-life of approximately 4 months was incorporated to describe a decrease in clearance (CL) in infants. Clearance [95% confidence interval (CI)] for a typical patient was 1.53 (1.34-1.78) L/h/kg(0.75) with an interindividual variability of 56.8%. Ondansetron CL was reduced by 31%, 53%, and 76% for the typical 6-month-, 3-month-, and 1-month-old patient, respectively. Simulations showed that an ondansetron dose of 0.1 mg/kg in children younger than 6 months produced exposure similar to a 0.15-mg/kg dose in older children. CONCLUSIONS: The population pharmacokinetic analysis of ondansetron allows for characterization of individual patients based on body weight and age. It is recommended that patients younger than 4 months receiving ondansetron be closely monitored.

Phase I and pharmacokinetic study of gefitinib in children with refractory solid tumors: a Children's Oncology Group Study.

PURPOSE: Epidermal growth factor receptor is expressed in pediatric malignant solid tumors. We conducted a phase I trial of gefitinib, an epidermal growth factor receptor tyrosine kinase inhibitor, in children with refractory solid tumors. PATIENTS AND METHODS: Gefitinib (150, 300, 400, or 500 mg/m2) was administered orally to cohorts of three to six patients once daily continuously until disease progression or significant toxicity. Pharmacokinetic studies were performed during course one (day 1 through 28). RESULTS: Of the 25 enrolled patients, 19 (median age, 15 years) were fully evaluable for toxicity and received 54 courses. Dose-limiting toxicity was rash in two patients treated with 500 mg/m2 and elevated ALT and AST in one patient treated with 400 mg/m2. The maximum-tolerated dose was 400 mg/m2/d. The most frequent non-dose-limiting toxicities were grade 1 or 2 dry skin, anemia, diarrhea, nausea, and vomiting. One patient with Ewing's sarcoma had a partial response. Disease stabilized for 8 to > or = 60 weeks in two patients with Wilms' tumor and two with brainstem glioma (one exophytic). At 400 mg/m2, the median peak gefitinib plasma concentration was 2.2 microg/mL (range, 1.2 to 3.6 microg/mL) and occurred at a median of 2.3 hours (range, 2.0 to 8.3 hours) after drug administration. The median apparent clearance and median half-life were 14.8 L/h/m2 (range, 3.8 to 24.8 L/h/m2) and 11.7 hours (range, 5.6 to 22.8 hours), respectively. Gefitinib systemic exposures were comparable with those associated with antitumor activity in adults. CONCLUSION: Oral gefitinib is well tolerated in children. Development of the drug in combination with cytotoxic chemotherapy will be pursued.

Gene therapy in the treatment of Fanconi anemia, a progressive bone marrow failure syndrome.

Fanconi anemia (FA) is a genetic disease characterized by progressive, fatal bone marrow failure, congenital anomalies and predisposition to cancer. Although stem cell transplantation is therapeutic, human leukocyte antigen-identical sibling donors are available to a minority of patients. In murine models and human cells in vitro, gene transfer corrects the FA cellular phenotype of chromosomal breakage in response to DNA-damaging agents, suggesting therapeutic use of gene transfer is possible. However, disease-specific characteristics make application of viral vector technology difficult. Multiple studies are currently underway to develop a gene therapy approach for treating this disease, including phase I trials.

Clinical course of postthrombotic syndrome in children with history of venous thromboembolism.

Postthrombotic syndrome (PTS) is a chronic morbidity of venous thromboembolism (VTE) in children. Information about the evolution of PTS is lacking in children. Present study was aimed to evaluate the time-course of extremity PTS in children who were serially followed in a hematology clinic. This retrospective cohort study included 69 consecutive children with documented VTEs that presented with symptoms of extremity VTE: 67 extremity VTEs with or without extension to vena cava, 2 inferior vena cava VTEs. Severity of PTS was assessed using modified Villalta scale. Median age of the cohort was 12.6 years (interquartile range 1.6-15 years) while median follow-up was 28.7 months (interquartile range 13.3-33.4 months. PTS prevalence was 46.8% [95% confidence interval (CI) 37.9-57.7%]. Lower extremity VTE was associated with development of PTS compared to upper extremity VTE regardless of catheter use (P = 0.002). The time-course of PTS fluctuated in 11 of 33 children (33%; 95% CI 20-47%) at a median interval of 12 months from diagnosis of VTE (range 4-14 months): three progressed from mild/moderate to severe, one improved from moderate to mild, seven fluctuated between mild and moderate. Recurrence and incomplete resolution of VTE were associated with variability in PTS severity (P < 0.05). In summary, this study suggested that almost 50% of study cohort developed PTS, and the time-course of PTS was not static in one third of children. Future research should focus on identifying the predictors contributing to the worsening of PTS and developing risk-stratified treatment interventions so as to improve the outcome of children with VTE.

Germline p53 mutation presenting as synchronous tumors.

Li-Fraumeni syndrome and the LF-like syndrome, rare heritable conditions that predispose to the development of malignancy, are associated with germline mutations of the tumor suppressor gene p53. The authors describe a 14-month-old boy who presented with synchronous rhabdomyosarcoma and adrenal cortical carcinoma and a novel mutation of the p53 gene. Analysis of exons 2 through 11 of the p53 gene using the polymerase chain reaction and DNA sequencing revealed a mutation of codon 273. Although codon 273 is a known hotspot region for p53 mutation, the patient's mutation, R273H, has not been associated with development of adrenal cortical carcinoma.

Treatment, outcome, and cost of care in children with idiopathic thrombocytopenic purpura.

Data were reviewed on treatment patterns, outcome, and hospital charges for children with idiopathic thrombocytopenic purpura (ITP). Records of 186 children with ITP, seen between January 1997 and April 2001, were reviewed. Hospital charges for initial management and first re-treatment were calculated by combining physician, hospital, and pathology charges. Anti-D immune globulin [anti-D IG] was used in 32.3%, intravenous immune globulin [IVIG] in 22.6%, steroids in 22.6%, combination therapies in 8%, and 14.5% were observed. Two patients had CNS bleeding, one with intraventricular hemorrhage at diagnosis, and the other with a parietal bleed 1 year from diagnosis. There was no significant differences in time to reach platelet counts of 20, 50, or 150 (x 10(9)/L) across different treatment groups. There was no significant difference in median charges for the IVIG and anti-D IG groups for the initial treatment of ITP. However, the IVIG was significantly more expensive than steroids or observation. Charges for the anti-D IG group were higher than the observation group but not the steroid group. After drug charges were excluded, patients in the IVIG group had statistically higher charges compared to patients in anti-D IG group. Almost half the patients were re-treated. There was no significant difference between anti-D IG, IVIG, and steroid groups when initial and re-treatment charges were combined. The observation group remained least expensive. Outcome for children with ITP is similar regardless of initial management. There is not a statistically significant difference in hospital charges between patients treated with anti-D IG and IVIG. The IVIG-treated group tends to be more costly, but this is not due to drug charges. Re-treatment is common and decreases the difference in patient charges among initial therapies.

Gene therapy for fanconi anemia.

Fanconi anemia is a hereditary syndrome of bone marrow failure, congenital anomalies, and a predisposition to malignancy. Most patients die from bone marrow failure. Cells from patients display a heightened sensitivity to DNA cross-linking agents with increased chromosomal breakage and increased cytotoxicity. Bone marrow from patients with Fanconi anemia have decreased numbers of hematopoietic progenitors when grown in culture. Transfer of the normal Fanconi anemia cDNA into cells from patients corrects the laboratory abnormalities, suggesting that gene transfer may prevent or reverse the bone marrow failure. Advances in gene transfer into human hematopoietic cells make this approach seem feasible. However, decreased numbers of stem cell targets may represent a significant obstacle. In addition, new insights on potential toxicities related to gene transfer have heightened a cautious approach. Fanconi anemia represents a prototype disorder for gene therapy and highlights the difficulties in adapting this technology to human disease.