Recovery of upland acid grasslands after successful Pteridium aquilinum control: Long-term effectiveness of cutting, repeated herbicide treatment and bruising

There is a clear need for the development of management strategies to control dominant, perennial weeds and restore semi-natural communities and an important part of this is to know how long control treatments take to be effective and how long they last after treatments stop. Here, we report the results from a 17-year long experiment where we compared the effects of five control treatments on dense Pteridium aquilinum (L. Kuhn) relative to an untreated experimental-control in Derbyshire, UK. The experiment was run in two phases. In Phase 1 (2005-2012) we controlled the P. aquilinum by cutting and bruising, both twice and thrice annually, and a herbicide treatment (asulam in year 1, followed by annual spot-re-treatment of all emergent fronds). In Phase 2 (2012-2021) all treatments were stopped, and the vegetation was allowed to develop naturally. Between 2005 and 2021 we monitored P. aquilinum performance annually and full plant species composition at intervals. Here, we concentrate on analysing the Phase 2 data where we used regression approaches to model individual species responses through time and unconstrained ordination to compare treatment effects on the entire species composition over both Phases. Remote sensing was also used to assess edge invasion in 2018. At the end of Phase 1, a good reduction of P. aquilinum and restoration of acid-grassland was achieved for the asulam and cutting treatments, but not for bruising. In Phase 2, P. aquilinum increased through time in all treated plots but the asulam and cutting ones maintained a much lower P. aquilinum performance for nine years on all measures assessed. There was a reduction in species richness and richness fluctuations, especially in graminoid species. However, multivariate analysis showed that the asulam and cutting treatments were stationed some distance from the untreated and bruising treatments with no apparent sign of reversions suggesting an Alternative Stable State had been created, at least over this nine-year period. P. aquilinum reinvasion was mainly from plot edges. The use of repeated P. aquilinum control treatments, either through an initial asulam spray with annual follow-up spot-spraying or cutting twice or thrice annually for eight years gave good P. aquilinum control and helped restore an acid-grassland community. Edge reinvasion was detected, and it is recommended that either whole-patch control be implemented or treatments should be continued around patch edges.

Outcomes of SARS-CoV-2 infection in 126 children and adolescents with central nervous system tumors

BACKGROUND

The Global Registry of COVID-19 in Childhood Cancer (GRCCC) seeks to describe the natural history of SARS-CoV-2 in children with cancer across the world. Here, we report the disease course and management of coronavirus disease 2019 (COVID-19) infection in the subset of children and adolescents with central nervous system (CNS) tumors who were included in the GRCCC until February 2021, the first data freeze.

PROCEDURE

The GRCCC is a deidentified web-based registry of patients less than 19 years of age with cancer or recipients of a hematopoietic stem cell transplant and laboratory-confirmed SARS-CoV-2 infection. Demographic data, cancer diagnosis, cancer-directed therapy, and clinical characteristics of SARS-CoV-2 infection were collected. Outcomes were collected at 30 and 60 days post infection.

RESULTS

The GRCCC included 1500 cases from 45 countries, including 126 children with CNS tumors (8.4%). Sixty percent of the cases were from middle-income countries, while no cases were reported from low-income countries. Low-grade gliomas, high-grade gliomas, and CNS embryonal tumors were the most common CNS cancer diagnoses (67%, 84/126). Follow-up at 30 days was available for 107 (85%) patients. Based on the composite measure of severity, 53.3% (57/107) of reported SARS-CoV-2 infections were asymptomatic, 39.3% (42/107) were mild/moderate, and 6.5% (7/107) were severe or critical. One patient died from SARS-CoV-2 infection. There was a significant association between infection severity and absolute neutrophil count less than 500 (p = .04). Of 107 patients with follow-up available, 40 patients (37.4%) were not receiving cancer-directed therapy. Thirty-four patients (50.7%) had a modification to their treatment due to withholding of chemotherapy or delays in radiotherapy or surgery.

CONCLUSION

In this cohort of patients with CNS tumors and COVID-19, the frequency of severe infection appears to be low, although severe disease and death do occur. We found that greater severity was seen in patients with severe neutropenia, although treatment modifications were not associated with infection severity or cytopenias. Additional analyses are needed to further describe this unique group of patients.

Health Equity in Pediatric Drug Development: Translating Aspiration into Operation

The concept of health equity—the attainment of the highest possible level of health for all members of society—requires equitable access to all aspects of healthcare, including pediatric drug development. However, many communities are under-represented in pediatric drug development programs. Barriers to participation include geographic, economic, racial/ethnic bias, legal, cultural, linguistic, and other factors. While there is no “one size fits all” approach to addressing these barriers, community engagement and collaboration is recognized by the Centers for Disease Control, the World Health Organization, and other global health organizations as a cornerstone for building a more equitable healthcare system. In this article, we will present case studies of stakeholder and community engagement in clinical research for rare diseases and other areas of healthcare, as examples of strategies and practices for actively involving under-represented communities and fostering their participation in pediatric drug development programs. These studies may serve as templates for facilitating equity in pediatric drug development from aspiration into operation.

Longer summer seasons after fire induce permanent drought legacy effects on Mediterranean plant communities dominated by obligate seeders

The ecological stability of Mediterranean ecosystems is being threatened by climate change. One of the impacts that is expected to be aggravated is the effect of summer drought prolongation toward previous or subsequent seasons by becoming more frequent. This, along with wildfires, could trigger synergistic negative effects on ecosystem regeneration capacity. Here we assessed how extending summer drought in two different ways (to autumn, AutExcl treatment, or bringing it forward to the following spring, SprExcl treatment) would affect plant recovery after an experimental fire carried out in summer in a Mediterranean seeder community. By installing rainout shelters, we assessed differences in seedling emergence, survival and establishment in the main families (Cistaceae, Labiatae, Leguminosae), and the effect on species richness and community composition. We observed that these post-fire dry season extensions reduced the total number of established seedlings and species richness. The most impacting drought treatment was AutExcl. However, the regeneration response was variable depending on the studied family. SprExcl was also determinant for Labiate survival rates. These results suggest that drought events which prolong the usual summer season may have a permanent drought legacy effect on seeder communities as practically all the seeder species populations were established in the first post-fire year. This fact is relevant for Mediterranean ecosystems dominated by seeder species as severer and longer droughts are increasingly recorded and are expected to become more frequent in forthcoming decades.

Limited contribution of post-fire eco-engineering techniques to support post-fire plant diversity

Eco-engineering techniques are generally effective at reducing soil erosion and restore vegetal cover after wildfire. However, less evidence exists on the effects of the post-fire eco-engineering techniques to restore plant diversity. To fill this knowledge gap, a standardized regional-scale analysis of the influence of post-fire eco-engineering techniques (log erosion barriers, contour felled log debris, mulching, chipping and felling, in some cases with burning) on species richness and diversity is proposed, adopting the Iberian Peninsula as case study. In general, no significant differences in species richness and diversity (Shannon) were found between the forest treated with different post-fire eco-engineering techniques, and the burned and non-treated soils. Only small significant differences were found for some sites treated with log erosion barriers or mulching. The latter technique increased species richness and diversity in some pine species and shrublands. Contour felled log debris with burning slightly increased vegetation diversity, while log erosion barriers, chipping and felling were not successful in supporting plant diversity. This research will help forest managers and agents in Mediterranean forest to decide the best postfire management option for wildfire affected forest, and in the development of more effective post-fire strategies.

Thinning and plantation of resprouting species redirect overstocked pine stands towards more functional communities in the Mediterranean basin

Post-fire regeneration in Pinus halepensis' forests, one of the most abundant vegetation types in the Mediterranean basin, often generates overstocked and vulnerable stands. They accumulate a high fuel load, increasing the risk of further fires, and present high levels of vulnerability due to their reduced seed production. In addition, these dense stands substantially reduce the availability of light and nutrients, which may hinder the recruitment of other species, often generating mono-specific and homogeneous stands, which potentially supply fewer ecosystem services than mixed forests with more heterogeneous structures. In these dense pine stands, management is of high priority to reduce fire hazards and promote their functionality. In overstocked pine stands (>75,000 trees·ha^-1), we assessed the long-term effects (10 years) of two thinning levels (600 and 1200 trees·ha^-1), in combination with the plantation of Quercus faginea (a resprouter species typical of advanced successional stages in our study area) on 28 above and belowground ecosystem attributes, including fire hazard. After ten years, thinning and plantation interacted to enhance ecosystem attributes associated with disturbance regulation and biodiversity conservation (up to 200%) and food production (up to 90%), while no effects were observed on those attributes related to carbon sequestration and supporting services. These effects were mainly driven by aboveground attributes, as they responded more strongly to our treatments than those belowground. Our results are relevant for the restoration of Mediterranean degraded ecosystems, and show that tree thinning in overstocked pine stands, combined with the plantation of resprouter species, may not only reduce fire risks and accelerate post-fire succession but also enhance the supply of multiple ecosystem services in the long run.

Impact of Neoadjuvant Chemotherapy on Image-Defined Risk Factors in High-Risk Neuroblastoma

PURPOSE

Image-defined risk factors (IDRFs) are associated with surgical risks in neuroblastoma. We sought to evaluate the impact of neoadjuvant therapy on IDRFs and associated ability to achieve gross total resection (GTR) of locoregional disease in patients with high-risk neuroblastoma.

METHODS

We retrospectively reviewed charts of patients treated on four consecutive high-risk neuroblastoma protocols over a 20-year period at a single institution. The number of IDRFs at diagnosis and just prior to surgery, and the percent decrease of tumor volume from just prior to surgery to the end of induction were determined.

RESULTS

Eighty-eight patients were included. There were 438 IDRFs (average 5.0 ± 3.1 per patient) at diagnosis and 198 (average 2.3 ± 1.9 per patient) after neoadjuvant chemotherapy (p < 0.01). A reduction in IDRFs was seen in 81.8% of patients with average decrease of 2.9 ± 2.5 per patient. The average percent reduction in tumor volume was 89.8 ± 18.9% and correlated with the number of IDRFs present after chemotherapy (p < 0.01). Three or fewer IDRFs prior to surgery was associated with the highest odds ratio for > 90% GTR at 9.33 [95% confidence interval 3.14-31.5].

CONCLUSION

Neoadjuvant chemotherapy reduced the number of IDRFs in the majority of patients with high-risk neuroblastoma. The number of IDRFs present after neoadjuvant therapy correlated with the extent of resection.

Global characteristics and outcomes of SARS-CoV-2 infection in children and adolescents with cancer (GRCCC): a cohort study

BACKGROUND

Previous studies have shown that children and adolescents with COVID-19 generally have mild disease. Children and adolescents with cancer, however, can have severe disease when infected with respiratory viruses. In this study, we aimed to understand the clinical course and outcomes of SARS-CoV-2 infection in children and adolescents with cancer.

METHODS

We did a cohort study with data from 131 institutions in 45 countries. We created the Global Registry of COVID-19 in Childhood Cancer to capture de-identified data pertaining to laboratory-confirmed SARS-CoV-2 infections in children and adolescents (<19 years) with cancer or having received a haematopoietic stem-cell transplantation. There were no centre-specific exclusion criteria. The registry was disseminated through professional networks through email and conferences and health-care providers were invited to submit all qualifying cases. Data for demographics, oncological diagnosis, clinical course, and cancer therapy details were collected. Primary outcomes were disease severity and modification to cancer-directed therapy. The registry remains open to data collection.

FINDINGS

Of 1520 submitted episodes, 1500 patients were included in the study between April 15, 2020, and Feb 1, 2021. 1319 patients had complete 30-day follow-up. 259 (19·9%) of 1301 patients had a severe or critical infection, and 50 (3·8%) of 1319 died with the cause attributed to COVID-19 infection. Modifications to cancer-directed therapy occurred in 609 (55·8%) of 1092 patients receiving active oncological treatment. Multivariable analysis revealed several factors associated with severe or critical illness, including World Bank low-income or lower-middle-income (odds ratio [OR] 5·8 [95% CI 3·8-8·8]; p<0·0001) and upper-middle-income (1·6 [1·2-2·2]; p=0·0024) country status; age 15-18 years (1·6 [1·1-2·2]; p=0·013); absolute lymphocyte count of 300 or less cells per mm3 (2·5 [1·8-3·4]; p<0·0001), absolute neutrophil count of 500 or less cells per mm3 (1·8 [1·3-2·4]; p=0·0001), and intensive treatment (1·8 [1·3-2·3]; p=0·0005). Factors associated with treatment modification included upper-middle-income country status (OR 0·5 [95% CI 0·3-0·7]; p=0·0004), primary diagnosis of other haematological malignancies (0·5 [0·3-0·8]; p=0·0088), the presence of one of more COVID-19 symptoms at the time of presentation (1·8 [1·3-2·4]; p=0·0002), and the presence of one or more comorbidities (1·6 [1·1-2·3]; p=0·020).

INTERPRETATION

In this global cohort of children and adolescents with cancer and COVID-19, severe and critical illness occurred in one fifth of patients and deaths occurred in a higher proportion than is reported in the literature in the general paediatric population. Additionally, we found that variables associated with treatment modification were not the same as those associated with greater disease severity. These data could inform clinical practice guidelines and raise awareness globally that children and adolescents with cancer are at high-risk of developing severe COVID-19 illness.

FUNDING

American Lebanese Syrian Associated Charities and the National Cancer Institute.

A Phase 1 and pharmacokinetic study evaluating daily or weekly schedules of the humanized anti-GD2 antibody hu14.18K322A in recurrent/refractory solid tumors

Hu14.18K322A is a humanized anti-GD2 monoclonal antibody with a single point mutation that reduces complement-mediated cytotoxicity, with a maximum tolerated dose (MTD) of 60 mg/m² daily for 4 days in children with recurrent/refractory neuroblastoma. We report additional results of a Phase 1 trial to determine the MTD and safety profile of hu14.18K322A in patients with osteosarcoma, and of an alternative schedule of weekly hu14.18K322A administration in patients with neuroblastoma or osteosarcoma. Eligible patients with recurrent/refractory osteosarcoma received hu14.13K22A daily x4 every 28 days in a Phase 1 traditional 3 + 3 dose escalation design. Additional patients with osteosarcoma were then enrolled to receive hu14.18K322A once weekly for 4 weeks per course. Patients with recurrent/refractory neuroblastoma were also enrolled on the weekly schedule at 50 mg/m²/dose. Six patients with osteosarcoma treated on the daily schedule received a median of 2 (range 1-6) courses; the recommended daily dose was established as 60 mg/m². Three patients had stable disease (SD) as best overall response. Five patients (3 neuroblastoma, 2 osteosarcoma) enrolled on the weekly schedule received a median of 1 (1-3) course; 2 achieved SD as best overall response. Pain, fever, hematologic toxicities, hyponatremia, and ocular/visual abnormalities were common toxicities among both schedules. Dose-limiting toxicities attributed to hu14.18K322A included anorexia and fatigue (n = 1). Pharmacokinetic profiles were similar between daily and weekly schedules. The recommended dose for patients with osteosarcoma receiving daily hu14.18K322A x4 is 60 mg/m². Patients receiving the weekly schedule experienced similar pharmacokinetics and toxicity profile as the daily schedule.

Role of implicit bias in pediatric cancer clinical trials and enrollment recommendations among pediatric oncology providers

BACKGROUND

Provider implicit bias can negatively affect clinician-patient communication. In the current study, the authors measured implicit bias training among pediatric oncology providers and exposure to implicit association tests (IATs). They then assessed associations between IATs for race and socioeconomic status (SES) and recommendations for clinical trial enrollment.

METHODS

A prospective multisite study was performed to measure implicit bias among oncology providers at St. Jude Children's Research Hospital and affiliate clinics. An IAT was used to assess bias in the domains of race and SES. Case vignettes were used to determine an association between bias and provider recommendation for trial enrollment. Data were analyzed using Student t tests or Wilcoxon tests for comparisons and Jonckheere-Terpstra tests were used for association.

RESULTS

Of the 105 total participants, 95 (90%) had not taken an IAT and 97 (92%) had no prior implicit bias training. A large effect was found for (bias toward) high SES (Cohen d, 1.93) and European American race (Cohen d, 0.96). The majority of participants (90%) had a vignette score of 3 or 4, indicating recommendation for trial enrollment for most or all vignettes. IAT and vignette scores did not significantly differ between providers at St. Jude Children's Research Hospital or affiliate clinics. No association was found between IAT and vignette scores for race (P = .58) or SES (P = .82).

CONCLUSIONS

The authors noted a paucity of prior exposure to implicit bias self-assessments and training. Although these providers demonstrated preferences for high SES and European American race, this did not appear to affect recommendations for clinical trial enrollment as assessed by vignettes.

A phase I trial of talazoparib and irinotecan with and without temozolomide in children and young adults with recurrent or refractory solid malignancies

BACKGROUND

Talazoparib combined with irinotecan and temozolomide demonstrated efficacy in a murine Ewing sarcoma model. Based on these data, we conducted a phase I trial of talazoparib and irinotecan with/without temozolomide in paediatric patients with recurrent/refractory solid malignancies.

PATIENTS AND METHODS

Cohorts of 3-6 patients with recurrent/refractory solid malignancies received escalating doses of oral talazoparib and intravenous irinotecan (arm A) and oral talazoparib, oral temozolomide and intravenous irinotecan (arm B) in a 3 + 3 design. Talazoparib was administered on days 1-6, and intravenous irinotecan and oral temozolomide were administered on days 2-6, of a 21-day course. Serum for talazoparib and irinotecan pharmacokinetics was obtained during course 1. UGT1A1 polymorphism and Schlafen family member 11 (SLFN11) immunohistochemical staining were performed.

RESULTS

Forty-one patients (20 males; median age, 14.6 years; 24 with recurrent disease) were evaluable for dose escalation. Twenty-nine and 12 patients were treated on arm A and arm B, respectively, for a total of 208 courses. The most common diagnosis was Ewing sarcoma (53%). The most common ≥grade III haematologic toxicities in arms A and B included neutropenia (78% and 31%, respectively) and thrombocytopenia (42% and 31%, respectively). In arms A and B, febrile neutropenia (24% and 14%, respectively) and diarrhoea (21% and 7%, respectively) were the most common ≥grade III non-hematologic toxicities. Six patients (Ewing sarcoma [5 patients] and synovial sarcoma [1 patient]) had a response (1 with a complete response, 5 with a partial response). The objective response rates were 10.3% (arm A) and 25% (arm B). Pharmacokinetic testing demonstrated no evidence of drug-drug interaction between talazoparib and irinotecan. UGT1A1 was not related to response. SLFN11 positivity was associated with best response to therapy.

CONCLUSIONS

The combination of talazoparib and irinotecan with/without temozolomide is feasible and active in Ewing sarcoma, and further investigation is warranted.

Fire regimes shape diversity and traits of vegetation under different climatic conditions

Changes in climate and land use are altering fire regimes in many regions across the globe. This work aims to study the influence of wildfire recurrence and burn severity on woody community structure and plant functional traits under different environmental conditions. We selected three study sites along a Mediterranean-Oceanic climatic gradient, where we studied the fire history and burn severity of the last wildfire. Four years after the last wildfire, we established 1776 1-m² plots where the percentage cover of each woody species was sampled. We calculated (i) structural parameters of the community such as total cover, alpha species richness, evenness and diversity (Shannon diversity index), and (ii) vegetation cover of each functional group (differentiating life forms, eco-physiological traits and regenerative traits). Focusing on community structure, results showed increases in species richness and diversity as wildfire recurrence increased, but this effect was partially counterweighted in the areas affected by high severity. In relation to functional groups, we found that increases in recurrence and severity fostered transition from tree- to shrub-dominated ecosystems. Non-arboreal life form, high specific leaf area, N₂-fixing capacity, resprouting ability and heat-stimulated germination were advantageous traits under high recurrences and severities, and low seed mass was advantageous under high recurrence situations. We suggest that the strength of the effects of wildfire recurrence and burn severity on vegetation structure and traits might vary with climate, increasing from Oceanic to Mediterranean conditions. In the Mediterranean site, recurrence and severity were strongly related to traits associated with germination (seed mass and heat-stimulated germination), whereas in the Oceanic site the strongest relationships were found with a resprouting-related trait (bud location). This study identifies changes in vegetation structure and composition in scenarios of high recurrence and severity, and provides useful information on plant traits that could be key in enhancing vegetation resilience.

Phase I expansion cohort to evaluate the combination of bevacizumab, sorafenib and low-dose cyclophosphamide in children and young adults with refractory or recurrent solid tumours

BACKGROUND

Angiogenesis is critical for tumour growth and metastasis. Dual inhibition of vascular endothelial growth factors and platelet-derived growth factor receptors suppresses angiogenesis. This expansion cohort of a phase I study targeted angiogenesis with sorafenib, bevacizumab and low-dose cyclophosphamide in children and young adults with recurrent solid tumours.

METHODS

An expansion cohort including patients with refractory or recurrent solid tumours was enrolled and received bevacizumab (15 mg/kg IV, day 1), sorafenib (90 mg/m² po twice daily, days 1-21) and low-dose cyclophosphamide (50 mg/m² po daily, days 1-21). Each course was 21 days. Toxicities were assessed using Common Terminology Criteria for Adverse Events, v3.0, and responses were evaluated by Response Evaluation Criteria in Solid Tumors criteria. Serial bevacizumab pharmacokinetic (PK) studies were performed during course 1.

RESULTS

Twenty-four patients (15 males; median age 14.5 yrs; range 1-22 yr) received a median of 6 courses (range 1-18). Twelve patients had a bone or soft tissue sarcoma. The most common grade III/IV non-haematologic toxicities were hypertension (N = 4), hand/foot rash (N = 3) and elevated lipase (N = 3). The most common grade III/IV haematologic toxicities were neutropenia (N = 7) and lymphopenia (N = 17). Three patients (2 synovial sarcoma, 1 rhabdoid tumour) achieved a partial response and 18 had stable disease. The progression-free survival at 3 and 6 months were 78.1% (95% confidence interval [CI] 60.6-95.6%) and 54% (95% CI 30.2-78.2%), respectively. Bevacizumab PKs in 15 patients was similar to published adult PK results.

CONCLUSIONS

Intravenous bevacizumab combined with oral sorafenib and low-dose cyclophosphamide was tolerated and demonstrated promising activity in a subset of childhood solid tumours.

Barriers and facilitators of clinical trial enrollment in a network of community-based pediatric oncology clinics

INTRODUCTION

Major advances in the field of pediatric oncology have resulted from rigorous, prospective clinical oncology research trials. Optimizing access for all children and adolescents to clinical research trials is an important goal. Barriers to clinical trial enrollment are numerous, involving the health care system, research infrastructure, access to care, providers, and participants. The perspectives of pediatric oncologists may provide insight into the barriers of clinical trial enrollment for this unique population.

METHODS AND MATERIALS

We conducted qualitative structured interviews over two months of pediatric oncologists in a community-based clinical network as part of a quality improvement project aimed at increasing enrollment rates at St. Jude Affiliate Clinics. We assessed barriers and facilitators to clinical trial opportunities for racial and ethnic minority pediatric participants. In the same fiscal year of the interviews, we tracked clinical trial enrollment by race and ethnicity of the participant over 12 months.

RESULTS

The major barriers to clinical trial enrollment for pediatric cancer minority participants included language discordance, travel difficulties, and complex trial designs. In contrast, the major facilitators included building trust with participants and their parents, and education on the merits of clinical research studies. We did not observe any disparities in clinical trial enrollment among the racial and ethnic minority participants of the clinical trials conducted across our network of pediatric oncology clinics.

CONCLUSIONS

Identifying barriers and facilitators may improve clinical trial enrollment for underrepresented participant groups.

Communication Regarding Therapeutic Clinical Trial Enrollment Between Oncologists and Adolescents and Young Adults with Cancer

Adolescent and young adult (AYA) cancer patients enroll in therapeutic clinical trials at low rates. Prior study has focused on trial availability; this research attempts to elucidate the role of communication in individual decision-making. We surveyed 193 AYA patients and reviewed medical records of informed consent discussions. Twenty percent (38/193) of patients were offered trials, 58% (22/38) enrolled. Many were unable to correctly identify whether they were offered trials or enrolled, including 27% (6/22) of patients on clinical trials who believed that they were not. Efforts to improve communication have potential to enhance informed decision-making in this vulnerable population.

Biochemical testing for neuroblastoma using plasma free 3-O-methyldopa, 3-methoxytyramine, and normetanephrine

BACKGROUND

Neuroblastoma, the most common extracranial solid tumor of childhood, produces catecholamines that are metabolized within tumor cells. Homovanillic acid (HVA) and vanillylmandelic acid (VMA), the end products of catecholamine metabolism, have limited accuracy for testing of the tumors. This study assessed whether metabolites produced in earlier steps of catecholamine metabolism might offer improved diagnostic accuracy over urinary HVA and VMA.

PROCEDURE

Plasma concentrations of 3-methoxytyramine, normetanephrine, and metanephrine were measured in two pediatric cohorts: (i) 96 children with confirmed neuroblastoma and (ii) 41 children with signs and symptoms of a catecholamine-producing tumor or other neoplasms and in whom neuroblastoma was excluded. Additional measurements of plasma 3-O-methyldopa and relationships of metabolites to MYCN amplification were examined in patient subgroups.

RESULTS

Overall, 94 of the 96 patients with neuroblastoma had concentrations of 3-methoxytyramine or normetanephrine above age-specific upper limits of reference intervals, providing a diagnostic sensitivity of 97.9% that was higher (P < 0.0001) than that of 82.2% for HVA and VMA. One of the two patients with normal plasma results showed an elevation of plasma 3-O-methyldopa. Diagnostic specificities were, respectively, 95.1% and 84.8%. Areas under receiver-operating characteristic curves confirmed the superior diagnostic power of the plasma than the urinary test (0.994 vs 0.945; P = 0.0095). Ratios of plasma 3-methoxytyramine to normetanephrine were 7.2-fold higher (P < 0.0001) for patients who had neuroblastomas with MYCN amplification than without MYCN amplification.

CONCLUSIONS

Measurements of plasma 3-methoxytyramine and normetanephrine provide a highly accurate diagnostic test for neuroblastoma and also offer potential for prognostic risk stratification.

Increased aridity drives post-fire recovery of Mediterranean forests towards open shrublands

Recent observations suggest that repeated fires could drive Mediterranean forests to shrublands, hosting flammable vegetation that regrows quickly after fire. This feedback supposedly favours shrubland persistence and may be strengthened in the future by predicted increased aridity. An assessment was made of how fires and aridity in combination modulated the dynamics of Mediterranean ecosystems and whether the feedback could be strong enough to maintain shrubland as an alternative stable state to forest. A model was developed for vegetation dynamics, including stochastic fires and different plant fire-responses. Parameters were calibrated using observational data from a period up to 100 yr ago, from 77 sites with and without fires in Southeast Spain and Southern France. The forest state was resilient to the separate impact of fires and increased aridity. However, water stress could convert forests into open shrublands by hampering post-fire recovery, with a possible tipping point at intermediate aridity. Projected increases in aridity may reduce the resilience of Mediterranean forests against fires and drive post-fire ecosystem dynamics toward open shrubland. The main effect of increased aridity is the limitation of post-fire recovery. Including plant fire-responses is thus fundamental when modelling the fate of Mediterranean-type vegetation under climate-change scenarios.

A phase 1 trial of everolimus and bevacizumab in children with recurrent solid tumors

BACKGROUND

The prognosis for children with recurrent solid tumors generally is poor. Targeting mammalian target of rapamycin (mTOR) and vascular endothelial growth factor A with everolimus and bevacizumab, respectively, synergistically improves progression-free survival and is well tolerated in adults with solid tumors.

METHODS

In the current phase 1 study, a total of 15 children with recurrent or refractory solid tumors were treated with bevacizumab and everolimus to establish the maximum tolerated dose, toxicity, and preliminary antitumor response (ClinicalTrials.gov identifier NCT00756340). The authors also evaluated everolimus-mediated inhibition of the mTOR pathway in the peripheral blood mononuclear cells of treated patients.

RESULTS

Tumors predominantly were soft tissue and/or bone sarcomas (8 cases) and brain tumors (5 cases). The first 2 patients enrolled at dose level 1 (10 mg/kg of bevacizumab and 4 mg/m² of everolimus) experienced dose-limiting toxicities (DLTs). The next 5 patients were enrolled at dose level 0 (8 mg/kg of bevacizumab and 4 mg/m² of everolimus), and DLTs occurred in 2 patients. The authors then modified the protocol to permit expansion of dose 0, and 8 additional patients were added, with no DLTs reported. Of all the patients, stable disease occurred in 4 patients (30.8%; median, 2 courses), and progressive disease occurred in 9 patients (69.2%). Overall survival was 0.59 years (95% CI, 0.24-1.05 years). The mTOR biomarker phospho-4EBP1 Thr/37/46 significantly decreased from baseline to day 27 in peripheral blood mononuclear cells (P = .045). Phospho-AKT levels also decreased from those at baseline.

CONCLUSIONS

The maximum tolerated dose of cotreatment with bevacizumab and everolimus was 8 mg/kg of bevacizumab and 4 mg/m² of everolimus in a 4-week cycle for children with recurrent solid tumors.

A Phase II Trial of Hu14.18K322A in Combination with Induction Chemotherapy in Children with Newly Diagnosed High-Risk Neuroblastoma

PURPOSE

We sought to evaluate whether combining a humanized antidisialoganglioside mAb (hu14.18K322A) with induction chemotherapy improves early responses and outcomes in children with newly diagnosed high-risk neuroblastoma.

PATIENTS AND METHODS

We conducted a prospective nonrandomized, single-arm, two-stage, phase II clinical trial. Six courses of induction chemotherapy were coadministered with hu14.18K322A and followed with granulocyte-macrophage colony-stimulating factor (GM-CSF) and low-dose IL2. Consolidation was performed with a busulfan/melphalan preparative regimen. An additional course of hu14.18K322A was administered with parent-derived natural killer cells, when available, during consolidation. Hu14.18K322A, GM-CSF, IL2, and isotretinoin were then administered. Secondary outcomes included reduced tumor volume and semiquantitative ¹²³I-metaiodobenzylguanidine scoring [i.e., Curie scores (CS)] at the end of induction.

RESULTS

Forty-two patients received hu14.18K322A and induction chemotherapy. This regimen was well tolerated, with continuous-infusion narcotics adjusted to patient tolerance. Partial responses (PR) or better after the first two chemoimmunotherapy courses occurred in 32 patients [76.2%; 95% confidence interval (CI), 60.6-88.0]. This was accompanied by primary tumor volume reductions (median, -76%; range, -100% to 5%). Of 35 patients with stage IV disease who completed induction, 31 had end-of-induction CSs of 2 or less. No patients experienced progression during induction. Two-year event-free survival (EFS) was 85.7% (95% CI, 70.9-93.3).

CONCLUSIONS

Adding hu14.18K322A to induction chemotherapy produced early PR or better in most patients, reduced tumor volumes, improved CSs at the end of induction, and yielded an encouraging 2-year EFS. These results, if validated in a larger study, may change the standard of care for children with high-risk neuroblastoma.

Determining success rates of the current pharmacokinetically guided dosing approach of topotecan in pediatric oncology patients

BACKGROUND

Topotecan is a chemotherapeutic agent that is active against many pediatric tumors. Although its effect is related to systemic exposure, the interpatient variability in systemic clearance makes it challenging to achieve desired topotecan targets. This study aims to evaluate the success of the pharmacokinetically (PK) guided dosing process, which was used to achieve a target topotecan area under the concentration-time curve (AUC).

METHODS

Patients received an empiric topotecan dosage on the first day; the topotecan lactone AUC was determined, and based upon these values the topotecan dosage was adjusted. The success rates of both the empiric and PK-guided strategies were calculated. Patient-specific covariates were collected to explain variability observed in the empiric and PK-guided results. A simulation study was performed to assess the differences in cumulative topotecan dosage and systemic exposure between a PK-guided and standard dosing approach.

RESULTS

Data were collected from nine clinical trials open from 1996 to 2016 (n = 232 patients). The empiric dosing success rate was 35.5%, while the PK-guided rate was 64.4%. A difference in mean serum creatinine was observed between successful empiric studies and those above the AUC target. Compared to a standard dosing approach, the PK-guided group had a higher average cumulative dosage and systemic exposure.

CONCLUSION

The low empiric dosing success rate indicates that additional studies are needed to refine the initial topotecan dosage. The role of renal function, measured as serum creatinine, remains to be elucidated. However, the PK-guided targeting success rate highlighted the need to account for variable topotecan systemic clearance.

Managing local-regional failure in children with high-risk neuroblastoma: A single institution experience

BACKGROUND

Intensification of systemic therapy for high-risk neuroblastoma (HRNB) has resulted in improved local control and overall survival (OS) leaving potential for de-escalation of primary site radiotherapy. The utility of primary site de-escalation should be evaluated in the context of potential for successful local-regional salvage. We evaluated salvage strategies and outcomes in patients with HRNB with local-regional recurrence as a component of first failure.

METHODS

Twenty of 89 patients with HRNB experienced local-regional recurrence as a component of first relapse after chemotherapy, radiotherapy, surgery, and stem cell transplant from 1997 to 2013. We reviewed salvage therapy strategies and disease control, and report on the impact of local therapy as salvage for local-regional relapse.

RESULTS

Six of 20 patients with local-regional failure (LRF) were alive after a median follow-up of 13 years (range, 0.9-25.2 years). Median OS was 4.6 years (95% CI, 0.6 to not reached) versus 0.6 years (95% CI, 0.05-2.6) after LRF with and without distant failure, respectively (P = 0.03). OS in patients receiving salvage radiotherapy was comparable to those receiving initial adjuvant but no salvage radiotherapy. Time to first failure and death was significantly impacted by the intensity of frontline systemic therapy (P = 0.03). Salvage radiotherapy reduced the hazard for subsequent LRF (hazard ratio 0.3, 95% CI 0.1-0.9, P = 0.04) but not OS (P = 0.07).

CONCLUSIONS

Our study highlights the potential of local control strategies at first failure in patients with LRF when primary site radiotherapy was initially omitted, and delineates potential selection factors which may further improve the therapeutic ratio.

Redirecting fire-prone Mediterranean ecosystems toward more resilient and less flammable communities

The extensive abandonment of agricultural lands in the Mediterranean basin has led to large landscapes being dominated by early-successional species, characterized by high flammability and an increasing fire risk. This fact promotes fire occurrence and places ecosystems in a state of arrested succession. In this work, we assessed the effectiveness of several restoration actions in redirecting these ecosystems toward more resilient communities dominated by resprouting species. These actions included the mechanical clearing of early-successional species, the plantation of resprouting species, and the combination of both treatments. For 13 years, we assessed shifts in the successional trajectory and ecosystem flammability by changes in: species composition, species richness, ecosystem evenness, the natural colonization of resprouting species, total biomass and proportion of dead biomass. We observed that the plantation and clearing combination was a suitable strategy to promote resilience. Species richness increased as well as the presence of the resprouting species introduced by planting. The natural colonization of the resprouting species was also enhanced. These changes in the successional trajectory were accompanied by a possible reduction of fire risk by reducing dead fuel proportion. These findings are relevant for the management of Mediterranean basin areas, but also suggest new tools for redirecting systems in fire-prone areas worldwide.

NCCN Guidelines Insights: Bone Cancer, Version 2.2017

The NCCN Guidelines for Bone Cancer provide interdisciplinary recommendations for treating chordoma, chondrosarcoma, giant cell tumor of bone, Ewing sarcoma, and osteosarcoma. These NCCN Guidelines Insights summarize the NCCN Bone Cancer Panel's guideline recommendations for treating Ewing sarcoma. The data underlying these treatment recommendations are also discussed.

A Pilot Trial of Humanized Anti-GD2 Monoclonal Antibody (hu14.18K322A) with Chemotherapy and Natural Killer Cells in Children with Recurrent/Refractory Neuroblastoma

Purpose: Anti-GD2 mAbs, acting via antibody-dependent cell-mediated cytotoxicity, may enhance the effects of chemotherapy. This pilot trial investigated a fixed dose of a unique anti-GD2 mAb, hu14.18K322A, combined with chemotherapy, cytokines, and haploidentical natural killer (NK) cells.Experimental Design: Children with recurrent/refractory neuroblastoma received up to six courses of hu14.18K322A (40 mg/m²/dose, days 2-5), GM-CSF, and IL2 with chemotherapy: cyclophosphamide/topotecan (courses 1,2), irinotecan/temozolomide (courses 3,4), and ifosfamide/carboplatin/etoposide (courses 5,6). Parentally derived NK cells were administered with courses 2, 4, and 6. Serum for pharmacokinetic studies of hu14.18K322A, soluble IL2 receptor alpha (sIL2Rα) levels, and human antihuman antibodies (HAHA) were obtained.Results: Thirteen heavily pretreated patients (9 with prior anti-GD2 therapy) completed 65 courses. One patient developed an unacceptable toxicity (grade 4 thrombocytopenia >35 days). Four patients discontinued treatment for adverse events (hu14.18K322A allergic reaction, viral infection, surgical death, second malignancy). Common toxicities included grade 3/4 myelosuppression (13/13 patients) and grade 1/2 pain (13/13 patients). Eleven patients received 29 NK-cell infusions. The response rate was 61.5% (4 complete responses, 1 very good partial response, 3 partial responses) and five had stable disease. The median time to progression was 274 days (range, 239-568 days); 10 of 13 patients (77%) survived 1 year. Hu14.18K322A pharmacokinetics was not affected by chemotherapy or HAHA. All patients had increased sIL2Rα levels, indicating immune activation.Conclusions: Chemotherapy plus hu14.18K322A, cytokines, and NK cells is feasible and resulted in clinically meaningful responses in patients with refractory/recurrent neuroblastoma. Further studies of this approach are warranted in patients with relapsed and newly diagnosed neuroblastoma. Clin Cancer Res; 23(21); 6441-9. ©2017 AACR.

A phase II trial evaluating the feasibility of adding bevacizumab to standard osteosarcoma therapy

Increased vascular endothelial growth factor (VEGF) expression in osteosarcoma correlates with a poor outcome. We conducted a phase II trial to evaluate the feasibility and efficacy of combining bevacizumab, a monoclonal antibody against VEGF, with methotrexate, doxorubicin and cisplatin (MAP) in patients with localized osteosarcoma. Eligible patients received two courses of MAP chemotherapy before definitive surgery at week 10. Bevacizumab (15 mg/kg) was administered 3 days before starting chemotherapy then on day 1 of weeks 3 and 5 of chemotherapy. After surgery, patients received MAP for a total of 29 weeks; bevacizumab was added every 2 or 3 weeks on day 1 of chemotherapy at least 5 weeks after surgery. Group sequential monitoring rules were used to monitor for unacceptable bevacizumab-related targeted toxicity (grade 4 hypertension, proteinuria or bleeding, grade 3 or 4 thrombosis/embolism, and grade 2-4 major wound complications). Thirty-one patients (median age 12.8 years) with localized osteosarcoma were enrolled. No unacceptable targeted toxicities were observed except for wound complications (9 minor and 6 major), which occurred in 15 patients; none required removal of prosthetic hardware or amputation. The estimated 4-year event-free survival (EFS) rate and overall survival rate were 57.5 ± 10.0% and 83.4 ± 7.8%, respectively. Eight (28%) of 29 evaluable patients had good histologic response (<5% viable tumor) to preoperative chemotherapy. The addition of bevacizumab to MAP for localized osteosarcoma is feasible but frequent wound complications are encountered. The observed histologic response and EFS do not support further evaluation of bevacizumab in osteosarcoma.

18F-FDG Uptake During Early Adjuvant Chemotherapy Predicts Histologic Response in Pediatric and Young Adult Patients with Osteosarcoma

The purpose of this study was to determine the relationship of ¹⁸F-FDG uptake in the primary tumor at diagnosis, during therapy, and after therapy with a histologic response and event-free survival in pediatric and young adult patients with osteosarcoma (OS). Methods: Serial (baseline and 5 and 10 wk after start of therapy) ¹⁸F-FDG PET/CT imaging was performed in patients with newly diagnosed OS treated uniformly in a therapeutic trial at a single institution. Whole-body images were obtained approximately 1 h after injection of ¹⁸F-FDG. Logistic regression was used to study the association of tumor uptake and changes in SUV_max between 0, 5, and 10 wk for both clinical endpoints. Results: Thirty-four patients (17 males; median age, 12.2 y; age range, 6.8-19.1 y) underwent PET imaging; 25 (74%) had localized disease. Primary tumor locations included the femur (n = 17; 50%), tibia (n = 9; 26%), and humerus (n = 5; 15%). Logistic regression showed that SUV_max at 5 wk (P = 0.034) and 10 wk (P = 0.022) and percentage change from baseline at 10 wk (P = 0.021) were highly predictive of a histologic response. Using SUV_max of 4.04 at week 5, SUV_max of 3.15 at week 10, and 60% decrease from baseline at week 10 as cutoff values, we determined that the respective sensitivities were 0.93, 0.93, and 0.79 and that the respective specificities were 0.53, 0.71, and 0.76. Conclusion: SUV_max on routine images at 5 or 10 wk and percentage change in SUV_max from baseline to week 10 were metabolic predictors of a histologic response in OS. These findings may be useful in the early identification of patients who are responding poorly to therapy and may benefit from a change in treatment.

Phase I study of talazoparib and irinotecan in children and young adults with recurrent/refractory solid tumors

10542

Background: Poly (ADP-ribose) Polymerase inhibitors (PARPi) target tumors with deficiencies in DNA repair mechanisms. Talazoparib (TAL), a potent PARP inhibitor, demonstrated significant efficacy in a Ewing sarcoma model when combined with DNA-damaging irinotecan (IRN). We performed a phase I trial to determine the maximum tolerated doses (MTDs) of TAL and IRN in pediatric patients with solid tumors. Methods: Cohorts of 3-6 eligible patients (pts) with recurrent/refractory solid tumors received escalating doses of oral (PO) TAL and intravenous (IV) IRN in a 3+3 design (Table 1). Each course was 21 days. Serum for TAL and IRN pharmacokinetics (PK) were obtained. Toxicities were assessed using CTCAE v.4 and responses were evaluated by RECIST v.1.1. Results: Twenty-four pts (9 male; median age, 11 years; 18 recurrent) received a median of 2 courses (range, 1-18). Fifteen pts had prior exposure to IRN. Table 1 summarizes the dose-limiting toxicities (DLTs) in course 1. The most common grade 3 or higher non-hematologic and hematologic toxicities in 82 evaluable courses were febrile neutropenia (5), elevated gamma-glutamyltransferase (GGT, 4), neutropenia (22) and lymphopenia (17). Two of 22 evaluable patients had a response (CR Ewing sarcoma, 18 courses; PR synovial sarcoma, 10 courses) and 9 had disease stabilization, median 4 courses (range, 4-10). Results of PK tests will be presented. Conclusions: The recommended phase II doses are TAL 600mcg/m2 (max 1000mcg/dose) days 1-6 and IRN 40mg/m2/day days 2-6. This regimen is feasible with evidence of anti-tumor activity and warrants further investigation. Clinical trial information: NCT02392793. [Table: see text]

Risk factors associated with metastatic site failure in patients with high-risk neuroblastoma

10557

Background: This retrospective study sought to identify predictors of metastatic site failure (MSF) in patients with high-risk (HR) neuroblastoma (NB). Methods: Seventy-six patients with HR NB treated on prospective trials at from 1997 to 2014 were eligible for inclusion. All patients were treated with induction chemotherapy (chemo) with surgery followed by myeloablative chemo & stem cell rescue. Primary & metastatic site (MS) RT were applied according to institutional protocol. CT & I-123 MIBG scans were used to assess Curie scores at diagnosis, post-induction, post-transplant & failure. Overall (OS), & progression-free survival (PFS) were described using the Kaplan-Meier estimator. Cox proportional hazards frailty (cphfR) & CPH regression (CPHr) were used to identify covariates predictive of MSF & new site MSF. Results: Forty-two (55%) patients had documented MSFs. Consolidative MS RT was applied to 30 MSs in 10 patients. Original site MSF occurred in 146 of 383 (38%) & 18 of 30 (60%) non-irradiated & radiated MSs respectively. Original site MSF occurred in post-induction MIBG avid lesions in 68 of 81 (84%) & 12 of 14 (85%) non-irradiated & radiated MSs respectively. The median OS & PFS were 61 mo (95% CI 42.6-NR) & 24.1 mo (95% CI 16.5-38.7). Univariate cphfR identified an increased hazard for original MSF when MIBG avid following induction chemo (HR 4.9, 95%CI 1.1-20.9, p = 0.03) & transplant (HR 7.3 95%CI 1.8-30.2, p = 0.006) relative to lesions that cleared after induction. Notably, MS RT nor site location did not modify the hazard for MSF. Multivariate CPHr identified inability to undergo transplant (HR 32.4 95%CI 9.3-96.8, p < 0.001) &/or maintenance chemo (HR 5.2, 95%CI 1.7-16.2, p = 0.005) & the presence of lung metastases (HR 4.4 95%CI 1.7-11.1, p = 0.002) at diagnosis as predictors of new site MSF. The new MSF free survival at 3 years was 25% vs. 87% in patients with high-risk factors relative to those without the risk factors suggesting limited benefit of consolidative MS RT in this population. Conclusions: Metastatic lesions that remained MIBG avid following induction chemo & post-transplant had an increased hazard for MSF. Consolidative site RT likely has limited benefit in patients with HR features.

Early response rates and Curie scores at end of induction: An update from a phase II study of an anti-GD2 monoclonal antibody (mAb) with chemotherapy (CT) in newly diagnosed patients (pts) with high-risk (HR) neuroblastoma (NB)

10534

Background: We are conducting a Phase II trial of the anti-GD2 mAb hu14.18K322A given concomitantly with CT in newly diagnosed pts with HR NB. Our primary objective is to compare the response rate (RR; defined as ≥ PR) after two courses of CT with cyclophosphamide (CTX)/topotecan (TPT) and hu14.18K322A with GM-CSF and IL-2 to the RR reported by Park et al. (JCO 29:4351, 2011), using identical CT with GCSF only, in a two-stage group sequential design. Semiquantitative MIBG scoring (Curie; CS) has been shown to be a prognostic indicator of outcome in pts with HR NB (Yanik et al, J Nucl Med, 2013), particularly, those with CS > 2 at end of induction (EoI) CT have inferior outcomes. Here we update the RR and report the CS at EoI CT. Methods: Pts received induction CT (6 cycles) as described by Park et al, with the addition of hu14.18K332A (on d 2-5; 40mg/m2/d x 4d), daily sc GM-CSF and sc IL-2 (1 x 106 IU/m2/dose) qod x 6. 123I-MIBG scans and scoring (CS) were obtained on all pts at diagnosis, after second course of CT and at EoI. Results: 42 evaluable pts completed the first two courses of CT (24 male, median age 2.9 yrs (range 6 m -15.2 yrs), 36 INSS 4, 19 MYCNamplified); 40/42 evaluable pts had measurable reductions in primary tumor volume after two courses of CT (median 79%, average 69%, range +5 – 100%). Responses (≥ PR) after two courses were seen in 32/42 (76.2%; 95% CI 61.3 – 87.9%); No mAb dose-reductions were made but 20/43 (47%) pts had infusion times extended. The development of human anti-human antibody reactivity (HAHA) to hu14.18K322A in the first 22 pts is minimal. Of the 36 INSS 4 pts, 1 withdrew prior to EoI and 2 are too early. The median CS at diagnosis for the 33 stage 4 pts who have completed induction CT was 18 (range 1 – 28). At EoI the median CS was 0 (range 0 -23); 29/33 INSS 4 pts had EoI CS ≤ 2. Conclusions: The addition of hu14.18K322A to two courses of CTX/TPT significantly improves the RR compared to two courses of CTX/TPT alone (32/42 vs 12/30 as reported by Park et al,; P = 0.000004). The improved median CS of the stage 4 patients from 18 at diagnosis to 0 at EoI suggest the improvement in early RR may translate into improved EFS as well. Clinical trial information: NCT01857934.

Modelling Carbon Emissions in Calluna vulgaris-Dominated Ecosystems when Prescribed Burning and Wildfires Interact

A present challenge in fire ecology is to optimize management techniques so that ecological services are maximized and C emissions minimized. Here, we modeled the effects of different prescribed-burning rotation intervals and wildfires on carbon emissions (present and future) in British moorlands. Biomass-accumulation curves from four Calluna-dominated ecosystems along a north-south gradient in Great Britain were calculated and used within a matrix-model based on Markov Chains to calculate above-ground biomass-loads and annual C emissions under different prescribed-burning rotation intervals. Additionally, we assessed the interaction of these parameters with a decreasing wildfire return intervals. We observed that litter accumulation patterns varied between sites. Northern sites (colder and wetter) accumulated lower amounts of litter with time than southern sites (hotter and drier). The accumulation patterns of the living vegetation dominated by Calluna were determined by site-specific conditions. The optimal prescribed-burning rotation interval for minimizing annual carbon emissions also differed between sites: the optimal rotation interval for northern sites was between 30 and 50 years, whereas for southern sites a hump-backed relationship was found with the optimal interval either between 8 to 10 years or between 30 to 50 years. Increasing wildfire frequency interacted with prescribed-burning rotation intervals by both increasing C emissions and modifying the optimum prescribed-burning interval for minimum C emission. This highlights the importance of studying site-specific biomass accumulation patterns with respect to environmental conditions for identifying suitable fire-rotation intervals to minimize C emissions.

Biological significance of dead biomass retention trait in Mediterranean Basin species: an analysis between different successional niches and regeneration strategies as functional groups

Standing dead biomass retention is considered one of the most relevant fuel structural traits to affect plant flammability. However, very little is known about the biological significance of this trait and its distribution between different functional groups. Our aim was to analyse how the proportion of dead biomass produced in Mediterranean species is related to the successional niche of species (early-, mid- and late-successional stages) and the regeneration strategy of species (seeders and resprouters). We evaluated biomass distribution by size classes and standing dead biomass retention in nine dominant species from the Mediterranean Basin in different development stages (5, 9, 14 and 26 years since the last fire). The results revealed significant differences in the standing dead biomass retention of species that presented a distinct successional niche or regeneration strategy. These differences were restricted to the oldest ages studied (>9 years). Tree and small tree resprouters, typical in late-successional stages, presented slight variations with age and a less marked trend to retain dead biomass, while seeder shrubs and dwarf shrubs, characteristic of early-successional stages, showed high dead biomass loads. Our results suggest that the species that tend to retain more dead branches are colonising species that may promote fire in early-successional stages.

Comparison of pain outcomes between two anti-GD2 antibodies in patients with neuroblastoma

BACKGROUND

Addition of anti-GD2 antibody ch14.18 to the treatment of neuroblastoma has improved outcomes. The most common side effect of ch14.18 is neuropathic pain, which may in part be complement-mediated. Hu14.18K322A is a humanized anti-GD2 antibody designed to diminish complement activation and induce less pain. We compare the pain outcomes in patients treated with ch14.18 and those treated with hu14.18K322A, and explore dose-dependent relationships between pain scores, opioid requirements, and complement levels in patients treated with hu14.18K322A.

PROCEDURE

Opioid (morphine equivalent mg/kg) and anxiolytic requirements during course 1 (4 days) in patients treated with hu14.18K322A and ch14.18 were reviewed. Correlations between antibody dose and pain scores, opioid requirements, and complement levels were examined for patients receiving hu14.18K322A.

RESULTS

Patients treated with hu14.18K322A (n = 19) had lower opioid requirements than those who received ch14.18 (n = 9). The differences in median opioid requirements (mg/kg) were statistically significant for the overall course (1.57 vs. 2.41, P = 0.019) as well as for Days 3 (0.34 vs. 0.65, P = 0.005), and 4 (0.32 vs. 0.64, P = 0.010). No difference in anxiolytic use was observed between the two groups. In the group treated with hu14.18K322A, we found a positive correlation between antibody dose administered and pain scores, but no correlation between antibody dose and opioid requirements or changes in complement levels.

CONCLUSIONS

In this retrospective analysis, hu14.18K322A induced less pain than ch14.18 based on opioid requirements. Pediatr Blood Cancer 2015;62:224-228. © 2014 Wiley Periodicals, Inc.

Adaptive functioning of childhood brain tumor survivors following conformal radiation therapy

Adaptive functioning is not often examined in childhood brain tumor (BT) survivors, with the few existing investigations relying on examiner interviews. Parent questionnaires may provide similar information with decreased burden. The purpose of this study was: (1) to examine adaptive behaviors in BT survivors relative to healthy peer and cancer survivor groups, and (2) to explore the validity of a parent questionnaire in relation to an examiner administered interview. Participants (age 13.11 ± 2.98 years) were BT survivors treated with conformal radiation therapy (n = 50), healthy siblings of BT survivors (n = 39) and solid tumor (ST) survivors who did not receive CNS-directed therapy (n = 40). Parents completed the Adaptive Behavior Assessment System–2nd Edition (ABAS-II). For a subset of the BT cohort (n = 32), examiners interviewed the parents using the Vineland Adaptive Behavior Scales (VABS) within 12 months. Groups differed significantly on each of the ABAS-II indices and the general adaptive composite, with the BT group scoring lower than the sibling and ST groups across indices. Executive functioning, but not IQ, was associated with adaptive skills; no clear pattern of clinical and demographic predictors was established. VABS scores were correlated with ABAS-II scores on nearly all indices. BT survivors showed significantly lower adaptive functioning when compared to healthy and cancer controls. The ABAS-II proved sensitive to these behavioral limitations and was consistent with scores on the VABS. The use of a parent questionnaire to assess adaptive functioning enhances survivorship investigations by increasing flexibility of assessment and decreasing examiner burden.

Safety and diagnostic accuracy of tumor biopsies in children with cancer

BACKGROUND

Tumor biopsies are central to the diagnosis and management of cancer and are critical to efforts in personalized medicine and targeted therapeutics. In the current study, the authors sought to evaluate the safety and accuracy of biopsies in children with cancer.

METHODS

All biopsies performed in children at the study institution with a suspected or established diagnosis of cancer from 2003 through 2012 were reviewed retrospectively. Patient characteristics and disease-related and procedure-related factors were correlated with procedure-related complications and diagnostic accuracy using logistic regression analysis.

RESULTS

A total of 1073 biopsies were performed in 808 patients. Of 1025 biopsies with adequate follow-up, 79 (7.7%) were associated with an adverse event, 35 (3.4%) of which were minor (grade 1-2) and 32 (3.1%) of which were major (grade 3-4) (grading was performed according to the National Cancer Institute Common Terminology Criteria for Adverse Events [version 4.0]). The most common major adverse events were blood transfusion (>10 mL/kg; 24 cases) and infection requiring intravenous antibiotics (6 cases). Eleven deaths (1.4%) occurred within 30 days after the procedure, but the procedure may have contributed to the outcome in only 2 cases. A total of 926 biopsies (90.3%) provided definitive histologic diagnoses. Using multivariable analysis, biopsy site, preprocedure hematocrit level, and body mass index were found to be associated with the risk of postprocedural complications (P<.0001, P<.0001, and P =.0029, respectively). Excisional biopsy and biopsy site were found to be independently associated with obtaining a diagnostic result (P =.0002 and P =.0008, respectively).

CONCLUSIONS

Tumor biopsies in children with cancer are associated with a low incidence of complications and a high rate of diagnostic accuracy. The predictive factors identified for adverse outcomes may aid in risk assessment and preprocedural counseling.

Flammability properties of British heathland and moorland vegetation: models for predicting fire ignition

Temperate ecosystems, for example British heathlands and moorlands, are predicted to experience an increase in severe summer drought and wildfire frequency over the next few decades. The development of fire ignition probability models is fundamental for developing fire-danger rating systems and predicting wildfire outbreaks. This work assessed the flammability properties of the fuel complex of British moorlands as a function of their moisture content under laboratory conditions. Specifically, we aimed to develop: (1) models of the probability of fire ignition in peat/litter fuel-beds (litter of four different plant species, Sphagnum moss and peat); (2) flammability properties in terms of ignitability, sustainability, consumability and combustibility of these peat/litter fuel-beds; (3) the probability of ignition in a canopy-layer of Calluna vulgaris (the most dominant heath/moor species in Britain) as a function of its dead-fuel proportion and moisture content; (4) the efficacy of standardized smouldering and flaming ignition sources in developing sustained ignitions. For this, a series of laboratory experiments simulating the fuel structure of moor vegetation were performed. The flammability properties in peat/litter fuel-beds were influenced strongly by the fuel moisture content. There were small differences in moisture thresholds for experiencing initial flaming ignitions (35-59%), however, the threshold for sustained ignitions (i.e. spreading a fixed distance from the ignition point) varied across a much wider range (19-55%). Litter/peat fuel-beds were classified into three groups: fuel-beds with high ignitability and combustibility, fuel-beds with high levels of sustainability, and fuel-beds with low levels in all flammability descriptors. The probability of ignition in the upper Calluna-vegetation layer was influenced by both the proportion of dead fuels and their moisture content, ranging from 19% to 35% of moisture as dead fuel proportion increased. Smouldering sources were more efficient in igniting peat/litter fuel-beds but in the Calluna-vegetation layer flaming sources performed better. This work can assist in improving the predictions of fire-rating systems implemented in British moorlands, by providing better warnings based on critical moisture thresholds for various fuel types.

Phase I trial of a novel anti-GD2 monoclonal antibody, Hu14.18K322A, designed to decrease toxicity in children with refractory or recurrent neuroblastoma

PURPOSE

The addition of immunotherapy, including a combination of anti-GD2 monoclonal antibody (mAb), ch14.18, and cytokines, improves outcome for patients with high-risk neuroblastoma. However, this therapy is limited by ch14.18-related toxicities that may be partially mediated by complement activation. We report the results of a phase I trial to determine the maximum-tolerated dose (MTD), safety profile, and pharmacokinetics of hu14.18K322A, a humanized anti-GD2 mAb with a single point mutation (K322A) that reduces complement-dependent lysis.

PATIENTS AND METHODS

Eligible patients with refractory or recurrent neuroblastoma received escalating doses of hu14.18K322A ranging from 2 to 70 mg/m(2) per day for 4 consecutive days every 28 days (one course).

RESULTS

Thirty-eight patients (23 males; median age, 7.2 years) received a median of two courses (range, one to 15). Dose-limiting grade 3 or 4 toxicities occurred in four of 36 evaluable patients and were characterized by cough, asthenia, sensory neuropathy, anorexia, serum sickness, and hypertensive encephalopathy. The most common non-dose-limiting grade 3 or 4 toxicities during course one were pain (68%) and fever (21%). Six of 31 patients evaluable for response by iodine-123 metaiodobenzylguanidine score had objective responses (four complete responses; two partial responses). The first-course pharmacokinetics of hu14.18K322A were best described by a two-compartment linear model. Median hu14.18K322A α (initial phase) and β (terminal phase) half-lives were 1.74 and 21.1 days, respectively.

CONCLUSION

The MTD, and recommended phase II dose, of hu14.18K322A is 60 mg/m(2) per day for 4 days. Adverse effects, predominately pain, were manageable and improved with subsequent courses.

Population pharmacokinetics of bevacizumab in children with osteosarcoma: implications for dosing

PURPOSE

To describe sources of interindividual variability in bevacizumab disposition in pediatric patients and explore associations among bevacizumab pharmacokinetics and clinical wound healing outcomes.

EXPERIMENTAL DESIGN

Before tumor resection, three doses of bevacizumab (15 mg/kg) were administered to patients (median age, 12.2 years) enrolled in a multi-institutional osteosarcoma trial. Serial sampling for bevacizumab pharmacokinetics was obtained from 27 patients. A population pharmacokinetic model was fit to the data, and patient demographics and clinical chemistry values were systematically tested as predictive covariates on model parameters. Associations between bevacizumab exposure and wound healing status were evaluated by logistic regression.

RESULTS

Bevacizumab concentration-time data were adequately described by a two-compartment model. Pharmacokinetic parameter estimates were similar to those previously reported in adults, with a long median (range) terminal half-life of 12.2 days (8.6 to 32.4 days) and a volume of distribution indicating confinement primarily to the vascular space, 49.1 mL/kg (27.1 to 68.3 mL/kg). Body composition was a key determinant of bevacizumab exposure, as body mass index percentile was significantly (P < 0.05) correlated to body-weight normalized clearance and volume of distribution. Furthermore, bevacizumab exposure before primary tumor resection was associated with increased risk of major wound healing complications after surgery (P < 0.05).

CONCLUSION

A population pharmacokinetic model for bevacizumab was developed, which demonstrated that variability in bevacizumab exposure using weight-based dosing is related to body composition. Bevacizumab dosage scaling using ideal body weight would provide an improved dosing approach in children by minimizing pharmacokinetic variability and reducing likelihood of major wound healing complications.

Temperature thresholds of physically dormant seeds and plant functional response to fire: variation among species and relative impact of climate change

Variation in dormancy thresholds among species is rarely studied but may provide a basis to better understand the mechanisms controlling population persistence. Incorporating dormancy-breaking temperature thresholds into existing trait frameworks could improve predictions regarding seed bank persistence, and subsequently species resilience in response to fire, climate change and anthropogenic management. A key ecological strategy for many species from fire-prone ecosystems is the possession of a long-lived seed bank, ensuring recovery after fire. Physical dormancy is dominant in these ecosystems and maintaining this dormancy is directly linked to seed bank persistence. We identified a suite of seed-related factors relevant to maintaining populations in fire-prone regions for 14 co-occurring physically dormant species. We measured variation in initial levels of dormancy and then applied experimental heating treatments, based on current seasonal temperatures and those occurring during fires, to seeds of all study species. Additionally, higher seasonal temperature treatments were applied to assess response of seeds to temperatures projected under future climate scenarios. Levels of germination response and mortality were determined to assess how tightly germination response was bound to either fire or seasonal cues. Six species were found to have dormancy cues bound to temperatures that only occur during fires (80°C and above) and were grouped as having obligate pyrogenic dormancy release. The remaining species, classified as having facultative pyrogenic dormancy, had lower temperature dormancy thresholds and committed at least 30% of seeds to germinate after summer-temperature treatments. Evidence from this study supports including dormancy-breaking temperature thresholds as an attribute for identifying functional types. High temperature thresholds for breaking dormancy, found in our obligate pyrogenic group, appear to be a fire-adapted trait, while we predict that species in the facultative group are most at risk to increased seed bank decay resulting from elevated soil temperatures under projected climate change.

Bone cancer

Primary bone cancers are extremely rare neoplasms, accounting for fewer than 0.2% of all cancers. The evaluation and treatment of patients with bone cancers requires a multidisciplinary team of physicians, including musculoskeletal, medical, and radiation oncologists, and surgeons and radiologists with demonstrated expertise in the management of these tumors. Long-term surveillance and follow-up are necessary for the management of treatment late effects related to surgery, radiation therapy, and chemotherapy. These guidelines discuss the management of chordoma, giant cell tumor of the bone, and osteosarcoma.

Clarifying the role of fire heat and daily temperature fluctuations as germination cues for Mediterranean Basin obligate seeders

BACKGROUND AND AIMS

This study aims to determine the role that both direct effects of fire and subsequent daily temperature fluctuations play in the seed bank dynamics of obligate seeders from the Mediterranean Basin. The short yet high soil temperatures experienced due to passage of fire are conflated with the lower, but longer, temperatures experienced by daily fluctuations which occur after removing vegetation. These germination cues are able to break seed dormancy, but it is difficult to assess their specific level of influence because they occur consecutively after summer fires, just before the flush of germination in the wet season (autumn).

METHODS

By applying experimental fires, seed treatments were imposed that combined fire exposure/non-fire exposure with exposure to microhabitats under a gradient of disturbance (i.e. gaps opened by fire, mechanical brushing and intact vegetation). The seeds used were representative of the main families of obligate seeders (Ulex parviflorus, Cistus albidus and Rosmarinus officinalis). Specifically, an assessment was made of (1) the proportion of seeds killed by fire, (2) seedling emergence under field conditions and (3) seeds which remained ungerminated in soil.

KEY RESULTS

For the three species studied, the factors that most influenced seedling emergence and seeds remaining ungerminated were microhabitats with higher temperature fluctuations after fire (gaps opened by fire and brushing treatments). The direct effect of fire decreased the seedling emergence of U. parviflorus and reduced the proportion of seeds of R. officinalis remaining ungerminated.

CONCLUSIONS

The relevance of depleting vegetation (and subsequent daily temperature fluctuation in summer) suggests that studies focusing on lower temperature thresholds for breaking seed dormancy are required. This fact also supports the hypothesis that the seeding capacity in Mediterranean Basin obligate seeders may have evolved as a response to a wide range of disturbances, and not exclusively to fire.

Phase I and clinical pharmacology study of bevacizumab, sorafenib, and low-dose cyclophosphamide in children and young adults with refractory/recurrent solid tumors

PURPOSE

To determine the maximum-tolerated dose (MTD), dose-limiting toxicities (DLT), pharmacokinetics, and pharmacodynamics of sorafenib, bevacizumab, and low-dose oral cyclophosphamide in children and young adults with recurrent/refractory solid tumors.

EXPERIMENTAL DESIGN

Sorafenib dose was escalated from 90 to 110 mg/m(2) twice daily with fixed doses of bevacizumab at 5 mg/kg every 3 weeks and cyclophosphamide at 50 mg/m(2) daily. Once sorafenib's MTD was established, bevacizumab dose was escalated. Each course was of 21 days. Pharmacokinetics and pharmacodynamics studies were conducted during the first course.

RESULTS

Nineteen patients (11 males; median age, 9.2 years) received a median of four courses (range, 1-23). DLTs during course 1 included grade 3 rash (two), increased lipase (one), anorexia (one), and thrombus (one). With an additional 71 courses of therapy, the most common toxicities ≥ grade 3 included neutropenia (nine), lymphopenia (nine), and rashes (four). Five of 17 evaluable patients had partial tumor responses, and five had disease stabilization (>2 courses). Median day 1 cyclophosphamide apparent oral clearance was 3.13 L/h/m(2). Median day 1 sorafenib apparent oral clearance was 44 and 39 mL/min/m(2) at the 2 dose levels evaluated, and steady-state concentrations ranged from 1.64 to 4.8 mg/L. Inhibition of serum VEGF receptor 2 (VEGFR2) was inversely correlated with sorafenib steady-state concentrations (P = 0.019).

CONCLUSION

The recommended phase II doses are sorafenib, 90 mg/m(2) twice daily; bevacizumab, 15 mg/kg q3 weeks; and cyclophosphamide, 50 mg/m(2) once daily. This regimen is feasible with promising evidence of antitumor activity that warrants further investigation.

Dose escalation of intravenous irinotecan using oral cefpodoxime: a phase I study in pediatric patients with refractory solid tumors

BACKGROUND

Administration of an oral cephalosporin allowed advancement of the dosage of oral irinotecan. This study investigates whether administration of an oral cephalosporin increases the maximum tolerated dose (MTD) of intravenous irinotecan.

PROCEDURE

Irinotecan was administered intravenously on Days 1-5 and Days 8-12 of a 21-day cycle with continuous oral cefpodoxime starting 2 days prior to irinotecan. Cohorts of 3-6 pediatric patients with refractory solid tumors were enrolled at 4 dosage levels, starting at the single-agent irinotecan MTD of 20 mg/m(2) /dose.

RESULTS

The 17 evaluable patients received 39 courses of therapy. None of the patients treated with 20 mg/m(2) /dose experienced dose-limiting toxicity (DLT). One of six patients treated at 30 mg/m(2) /dose experienced dose-limiting neutropenia. Two of three patients treated with 45 mg/m(2) /dose and two of five treated with 40 mg/m(2) /dose experienced dose-limiting diarrhea, with associated dehydration and anorexia. Two unconfirmed partial responses were observed after one course in a patient with Ewing sarcoma and one with paraganglioma. A child with refractory neuroblastoma had disease stabilization through 12 courses of therapy. Median (range) systemic exposure to SN-38 at the MTD (30 mg/m(2) /dose) was 67 ng-h/mL (36 to 111 ng-h/mL).

CONCLUSIONS

The MTD of intravenous irinotecan administered on a protracted schedule was increased by 50% from 20 to 30 mg/m(2) /dose with the addition of oral cefpodoxime. The most prominent DLT remained diarrhea. High interpatient variability in irinotecan pharmacokinetics was observed; however, SN-38 exposure at the MTD was greater than most reported exposures with the 20 mg/m(2) dosage.

The role of neoadjuvant chemotherapy in children with malignant solid tumors

Pediatric surgeons play a critical role in diagnosing, staging, and treating malignant solid tumors in children. Over the years, the surgical management of the primary tumor site has evolved from an aggressive en-bloc resection at diagnosis to a more tailored surgical approach, often affecting definitive local control after the delivery of neoadjuvant therapy, as currently directed by many solid tumor protocols. In fact, inappropriate upfront resection can lead to unnecessary short- and long-term morbidity, an incomplete resection, and may be associated with a delay in the initiation of the systemic chemotherapy that is critical to the treatment of gross or occult metastatic disease. Therefore, it is important for the pediatric surgeon, as a member of the multidisciplinary team involved in the care of these children, to understand the indications for and implications of neoadjuvant therapy in the treatment of pediatric solid tumors. Here we review the current management of childhood solid tumors focusing on the role of neoadjuvant therapy.

Pilot induction regimen incorporating pharmacokinetically guided topotecan for treatment of newly diagnosed high-risk neuroblastoma: a Children's Oncology Group study

PURPOSE

To assess the feasibility of adding dose-intensive topotecan and cyclophosphamide to induction therapy for newly diagnosed high-risk neuroblastoma (HRNB).

PATIENTS AND METHODS

Enrolled patients received two cycles of topotecan (approximately 1.2 mg/m(2)/d) and cyclophosphamide (400 mg/m(2)/d) for 5 days followed by four cycles of multiagent chemotherapy (Memorial Sloan-Kettering Cancer Center [MSKCC] regimen). Pharmacokinetically guided topotecan dosing (target systemic exposure with area under the curve of 50 to 70 ng/mL/hr) was performed. Peripheral-blood stem cell (PBSC) harvest and surgical resection of residual primary tumor occurred after cycles 2 and 5, respectively. Patients achieving at least a partial response received myeloablative chemotherapy with PBSC rescue and radiation to the presurgical primary tumor volume. Oral 13-cis-retinoic acid maintenance therapy was administered twice daily for 14 days in six 28-day cycles.

RESULTS

Thirty-one patients were enrolled onto the study. No deaths related to toxicity or dose-limiting toxicities occurred during induction. Mucositis rarely occurred after topotecan cycles (9.7%) in contrast to 30% after MSKCC cycles. Thirty patients underwent PBSC collection with median 31.1 × 10(6) CD34+ cells/kg (range, 1.8 to 541.8 × 10(6) CD34+ cells/kg), all negative for tumor contamination by immunocytochemical analysis. Targeted topotecan systemic exposure was achieved in 26 (84%) of 31 patients. At the end of induction, 26 patients (84%) had tumor response and one patient had progressive disease. In the overall cohort, 3-year event-free and overall survival were 37.8% ± 9.4% and 57.1% ± 9.4%, respectively.

CONCLUSION

This pilot induction regimen was well tolerated with expected and reversible toxicities. These data support investigation of efficacy in a phase III clinical trial for newly diagnosed HRNB.

A single-arm pilot phase II study of gefitinib and irinotecan in children with newly diagnosed high-risk neuroblastoma

BACKGROUND

Gefitinib potently inhibits neuroblastoma proliferation in vitro, and the gefitinib/irinotecan combination shows greater than additive activity against neuroblastoma xenografts. This Phase II pilot study estimated the rate of response to two courses of intravenous irinotecan plus oral gefitinib in children with untreated high-risk neuroblastoma.

METHODS

Two courses of irinotecan [15 mg/m(2)/day (daily ×5)×2] were combined with 12 daily doses of gefitinib (112.5 mg/m(2)/day). Response was assessed after 6 weeks. A response rate >55% was sought.

RESULTS

Of the 23 children enrolled, 19 were evaluable for response. Median age at diagnosis was 3.1 years (range, 18 days-12.7 years). Most patients were older than 24 months (n = 20; 87%), male (n = 18; 78%), white (n = 16; 70%), had INSS 4 disease (n = 19; 83%), and had adrenal primary tumors (n = 18; 78%); nine patients (39%) had amplified tumor MYCN. The toxicity of gefitinib/irinotecan was mild and reversible (nausea, 5/20; diarrhea, 8/20; vomiting, 7/20). Five patients had partial responses; 9 others had a 23%-60% decrease in primary tumor volume and/or improved MIBG scans or decreased bone or bone marrow tumor burden. Median (range) systemic irinotecan exposure (AUC) was 283 ng/ml*hr (range, 163-890 ng/ml*hr) and 28 ng/ml*hr (3.6-297 ng/ml*hr) for the active metabolite, SN-38. No relation was observed between response and tumor expression of EGFR, MRP2-4, ABCG2, and Pgp.

CONCLUSIONS

Although the gefitinib/irinotecan combination was very tolerable and induced responses, it was not sufficiently active to warrant further investigation. Initial investigational studies of this type can preclude the necessity for larger, longer, and costlier trials.

Phase I study of temsirolimus in pediatric patients with recurrent/refractory solid tumors

PURPOSE

To determine dose-limiting toxicities, maximum-tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of weekly intravenous temsirolimus, a mammalian target of rapamycin (mTOR) signaling pathway inhibitor, in pediatric patients with recurrent or refractory solid tumors.

PATIENTS AND METHODS

Cohorts of three to six patients 1 to 21 years of age with recurrent or refractory solid tumors were treated with a 1-hour intravenous infusion of temsirolimus weekly for 3 weeks per course at one of four dose levels: 10, 25, 75, or 150 mg/m(2). During the first two courses, pharmacokinetic and pharmacodynamic evaluations (phosphorylation of S6, AKT, and 4EBP1 in peripheral-blood mononuclear cells) were performed.

RESULTS

Dose-limiting toxicity (grade 3 anorexia) occurred in one of 18 evaluable patients at the 150 mg/m(2) level, which was determined to be tolerable, and an MTD was not identified. In 13 patients evaluable for response after two courses of therapy, one had complete response (CR; neuroblastoma) and five had stable disease (SD). Four patients (three SDs + one CR) remained on treatment for more than 4 months. The sum of temsirolimus and sirolimus areas under the concentration-time curve was comparable to values in adults. AKT and 4EBP1 phosphorylation were inhibited at all dose levels, particularly after two courses.

CONCLUSION

Weekly intravenous temsirolimus is well tolerated in children with recurrent solid tumors, demonstrates antitumor activity, has pharmacokinetics similar to those in adults, and inhibits the mTOR signaling pathway in peripheral-blood mononuclear cells. Further studies are needed to define the optimal dose for use in combination with other antineoplastic agents in pediatric patients.