Abstract C036: Discovery of IACS-13909, an allosteric SHP2 inhibitor that overcomes multiple mechanisms underlying osimertinib resistance

Osimertinib, a third generation EGFR inhibitor, is a front-line therapy for EGFR mutated non-small lung cancer (NSCLC). The long-term effectiveness of osimertinib is limited by acquired resistance. Clinically identified resistance mechanisms include EGFR-dependent mechanisms such as mutations on EGFR that preclude drug binding, and EGFR-independent activation of the MAPK pathway, for instance via activation of alternate RTKs. It has also been noted that frequently a tumor from a single patient harbors more than one resistance mechanism, and the plasticity between the multiple resistance mechanisms will restrict the effectiveness of therapies targeting a single node of the oncogenic signaling network. SHP2 (Src homology 2 domain-containing phosphatase) is a phosphatase that mediates the signaling of multiple RTKs and is required for full activation of the MAPK pathway. Here we report IACS-13909 - a specific and potent allosteric inhibitor of SHP2 - suppresses the signaling of RTK/MAPK pathway. IACS-13909 potently impedes the proliferation of tumors with a broad spectrum of RTKs as the oncogenic driver. Importantly, in NSCLC models with acquired resistance to osimertinib, IACS-13909 administered as a single agent or in combination with osimertinib potently reduces tumor cell proliferation in vitro and in vivo. Together, our findings provide preclinical evidence for using a SHP2 inhibitor as a therapeutic strategy in acquired EGFR inhibitor-resistant NSCLC. Currently, a compound that potently inhibits SHP2 has been selected as the clinical development candidate and is undergoing IND-enabling studies with a projected first-in-human target of early 2020.

Citation Format: Yuting Sun, Brooke A Meyers, Sarah B Johnson, Angela L Harris, Barbara Czako, Jason B Cross, Paul G Leonard, Faika Mseeh, Maria E Di Francesco, Connor A Parker, Qi Wu, Christopher A Bristow, Jason P Burke, Caroline C Carrillo, Christopher L Carroll, Qing Chang, Ningping Feng, Sonal Gera, Gao Guang, Justin Kwang-Lay Huang, Yongying Jiang, Zhijun Kang, Jeffrey J Kovacs, Xiaoyan Ma, Pijus K Mandal, Timothy McAfoos, Robert A Mullinax, Michael D Peoples, Vandhana Ramamoorthy, Sahil Seth, Erika Suzuki, Christopher Conrad Williams, Simon S Yu, Andy M Zuniga, Giulio F Draetta, Joseph R Marszalek, Timothy P Heffernan, Nancy E Kohl, Philip Jones. Discovery of IACS-13909, an allosteric SHP2 inhibitor that overcomes multiple mechanisms underlying osimertinib resistance [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr C036. doi:10.1158/1535-7163.TARG-19-C036

Home Oxygen Therapy for Children. An Official American Thoracic Society Clinical Practice Guideline

Background: Home oxygen therapy is often required in children with chronic respiratory conditions. This document provides an evidence-based clinical practice guideline on the implementation, monitoring, and discontinuation of home oxygen therapy for the pediatric population.

Methods: A multidisciplinary panel identified pertinent questions regarding home oxygen therapy in children, conducted systematic reviews of the relevant literature, and applied the Grading of Recommendations, Assessment, Development, and Evaluation approach to rate the quality of evidence and strength of clinical recommendations.

Results: After considering the panel’s confidence in the estimated effects, the balance of desirable (benefits) and undesirable (harms and burdens) consequences of treatment, patient values and preferences, cost, and feasibility, recommendations were developed for or against home oxygen therapy specific to pediatric lung and pulmonary vascular diseases.

Conclusions: Although home oxygen therapy is commonly required in the care of children, there is a striking lack of empirical evidence regarding implementation, monitoring, and discontinuation of supplemental oxygen therapy. The panel formulated and provided the rationale for clinical recommendations for home oxygen therapy based on scant empirical evidence, expert opinion, and clinical experience to aid clinicians in the management of these complex pediatric patients and identified important areas for future research.

Harmonized outcome measures for use in asthma patient registries and clinical practice

BACKGROUND

Asthma, a common chronic airway disorder, affects an estimated 25 million persons in the United States and 330 million persons worldwide. Although many asthma patient registries exist, the ability to link and compare data across registries is hindered by a lack of harmonization in the outcome measures collected by each registry.

OBJECTIVES

The purpose of this project was to develop a minimum set of patient- and provider-relevant standardized outcome measures that could be collected in asthma patient registries and clinical practice.

METHODS

Asthma registries were identified through multiple sources and invited to join the workgroup and submit outcome measures. Additional measures were identified through literature searches and reviews of quality measures and consensus statements. Outcome measures were categorized by using the Agency for Healthcare Research and Quality's supported Outcome Measures Framework. A minimum set of broadly relevant measures was identified. Measure definitions were harmonized through in-person and virtual meetings.

RESULTS

Forty-six outcome measures, including those identified from 13 registries, were curated and harmonized into a minimum set of 21 measures in the Outcome Measures Framework categories of survival, clinical response, events of interest, patient-reported outcomes, resource utilization, and experience of care. The harmonized definitions build on existing consensus statements and are appropriate for adult and pediatric patients.

CONCLUSIONS

The harmonized measures represent a minimum set of outcomes that are relevant in asthma research and clinical practice. Routine and consistent collection of these measures in registries and other systems would support creation of a national research infrastructure to efficiently address new questions and improve patient management and outcomes.

Differentiating non-responders from responders in children with moderate and severe asthma exacerbations

Objective: Our goal was to assess factors associated with non-response to treatment in children presenting to the Emergency Department (ED) with moderate and severe asthma exacerbations. Methods: A retrospective chart review was completed from 9/2014 to 2/2017 for patients with a discharge diagnosis of asthma exacerbation. The Modified Pulmonary Index Score (MPIS) was used to quantify illness acuity. The rate of change of MPIS per hour was calculated, and differentiated responders from non-responders. After examining a histogram of ΔMPIS/h, a threshold of ΔMPIS/h > 0 was used to define response for duration of ED stay. Children included were >2 years and had initial MPIS > 10. Results: Eight hundred and fifty-two children were included. There were 178 (21%) non-responders and 674 (79%) responders. Non-responders were significantly older (7.0 ± 4.0 versus 5.6 ± 3.2 years; p < 0.001), but there were no differences in gender, race, ethnicity or insurance status. There was also no statistical difference in time to first albuterol treatment (50 ± 41 versus 43 ± 40 min; p = 0.05), or in time to corticosteroid (95 ± 75 versus 79 ± 64 min; p = 0.06). Non-responders were significantly more likely to arrive by ambulance (OR 2.2; 95% CI 1.6-3.2), to be admitted to the hospital (OR 2.7; 95% CI 1.8-4.0), and to be admitted to the ICU (OR 5.0; 95% CI 3.1-8.1). Conclusions: One in five children with exacerbations did not respond to treatment. These children were older and more likely to be admitted. Non-measured factors, possibly genetic, may contribute to response to treatment.

Estimating the probability of abusive head trauma after abuse evaluation

BACKGROUND

Evidence-based, patient-specific estimates of abusive head trauma probability can inform physicians' decisions to evaluate, confirm, exclude, and/or report suspected child abuse.

OBJECTIVE

To derive a clinical prediction rule for pediatric abusive head trauma that incorporates the (positive or negative) predictive contributions of patients' completed skeletal surveys and retinal exams.

PARTICIPANTS AND SETTING

500 acutely head-injured children under three years of age hospitalized for intensive care at one of 18 sites between 2010 and 2013.

METHODS

Secondary analysis of an existing, cross-sectional, prospective dataset, including (1) multivariable logistic regression to impute the results of abuse evaluations never ordered or completed, (2) regularized logistic regression to derive a novel clinical prediction rule that incorporates the results of completed abuse evaluations, and (3) application of the new prediction rule to calculate patient-specific estimates of abusive head trauma probability for observed combinations of its predictor variables.

RESULTS

Applying a mean probability threshold of >0.5 to classify patients as abused, the 7-variable clinical prediction rule derived in this study demonstrated sensitivity 0.73 (95% CI: 0.66-0.79) and specificity 0.87 (95% CI: 0.82-0.90). The area under the receiver operating characteristics curve was 0.88 (95% CI: 0.85-0.92). Patient-specific estimates of abusive head trauma probability for 72 observed combinations of its seven predictor variables ranged from 0.04 (95% CI: 0.02-0.08) to 0.98 (95% CI: 0.96-0.99).

CONCLUSIONS

Seven variables facilitate patient-specific estimation of abusive head trauma probability after abuse evaluation in intensive care settings.

Abstract PR01: IACS-010759 a novel inhibitor of oxidative phosphorylation advancing into first-in-human studies to exploit metabolic vulnerabilities

Tumor cells normally depend on both glycolysis and oxidative phosphorylation (OXPHOS) to provide the energy and macromolecule building blocks needed to enable continued tumor cell growth. Genetic or epigenetic inactivation of one of these two redundant pathways represents a metabolic vulnerability that should be susceptible to an inhibitor of the other pathway. We have identified multiple contexts where all or a subset of these tumors demonstrate a dependence on mitochondrial OXPHOS, which represents an exciting therapeutic opportunity.

Through an extensive medicinal chemistry campaign, IACS-10759 was identified as a potent inhibitor of complex I of oxidative phosphorylation. In isolated mitochondria or permeabilized cells, ATP production or oxygen consumption is inhibited at single digit nM concentrations in the presence of malate/glutamate, but not succinate. More directly, IACS-10759 inhibits the conversion of NADH to NAD+ in an immunoprecipitated complex I assay at low nM concentrations. Importantly, IACS-10759 is orally bioavailable with excellent pharmacokinetics properties in preclinical species, and has an overall profile suitable for clinical development.

Our group and others have demonstrated that a variety of tumor types including: AML, plus subsets of lymphoma, breast, melanoma and PDAC are highly dependent on OXPHOS to meet energy and biomass demands. Treatment of multiple cell lines and patient derived xenograft (PDX) models in multiple cancer types with IACS-10759 led to decreased oxygen consumption rate (OCR). IACS-10759 treatment also led to a robust decrease in cell viability and often an increase in apoptosis with EC50 values between 1 nM - 50 nM across multiple lines. In multiple PDX models of primary AML IACS-10759 treatment extends the median survival. Efficacy was paralleled by robust modulation of OCR, aspartate, and p-AMPK levels. Additionally, tumor growth inhibition or regression was also observed in cell line and PDX xenograft models of lymphoma, triple negative breast, melanoma and PDAC treated with IACS-10759, indicating that subsets of several non-AML indications are also dependent on OXPHOS. Mechanistically, extensive metabolic profiling revealed that the response to IACS-10759 was associated with induction of a metabolic imbalances that negatively impacted energy homeostasis, amino acid biosynthesis, and NTP production due to reduced conversion of NADH to NAD+ by complex I, decreased ATP production, TCA cycle flux and nucleotide biosynthesis.

As a result of the robust preclinical response in multiple model systems, IACS-10759 has been advanced through IND enabling studies. GLP safety and toxicology have been completed, clinical supplies manufactured, and a Phase I clinical trial in AML will be initiated during the second quarter of 2016.

This abstract is also being presented as Poster B35.

Citation Format: Philip Jones, M Emilia Di Francesco, Jennifer M. Molina, Marina Protopopova, Madhavi Bandi, Jennifer Bardenhagen, Christopher A. Bristow, Christopher L. Carroll, Ningping Feng, Jason P. Gay, Mary K. Geck Do, Jennifer M. Greer, Marina Konopleva, Zhijun Kang, Gang Liu, Timothy McAfoos, Pietro Morlacchi, Melinda G. Smith, Sonal Fnu, Jay P. Theroff, Giulio Draetta, Giulio Draetta, Carlo Toniatti, Joseph R. Marszalek. IACS-010759 a novel inhibitor of oxidative phosphorylation advancing into first-in-human studies to exploit metabolic vulnerabilities. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Targeting the Vulnerabilities of Cancer; May 16-19, 2016; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2017;23(1_Suppl):Abstract nr PR01.

A regional cohort study of the treatment of critically ill children with bronchiolitis

OBJECTIVE

To describe the treatment practices in critically ill children with RSV bronchiolitis across four regional PICUs in the northeastern United States, and to determine the factors associated with increased ICU length of stay in this population.

METHODS

We conducted a retrospective cohort study of children who were admitted with RSV bronchiolitis between July 2009 and July 2011 to the PICUs of Connecticut Children's Medical Center, Yale-New Haven Children's Hospital, Maria Fareri Children's Hospital, and Baystate Children's Hospital. Data were collected regarding clinical characteristics and intensive care course among these hospitals.

RESULTS

During the study period, 323 children were admitted to one of the four ICUs with RSV bronchiolitis. Despite similar mortality risk scores among ICUs, there was considerable variation in the use of therapies, particularly intubation and mechanical ventilation, in which there was greater than a 3.5-fold increased risk of intubation between sites with the highest and lowest frequency of intubation (odds ratio: 3.8; 95% confidence interval: 2.2-6.4). Albuterol was the most commonly used respiratory treatment, followed by chest physiotherapy, high-flow nasal cannula, and hypertonic saline. Longer stays in the ICU were associated with more frequent use of therapies, specifically invasive mechanical ventilation, inhaled corticosteroids, intrapulmonary percussive ventilation, and chest physiotherapy.

CONCLUSIONS

Even within a close geographic region, there is significant variation in the treatment provided to critically ill children with RSV bronchiolitis. None of these treatments were associated with shorter durations of hospitalization in this population and some, such as mechanical ventilation, were associated with longer ICU lengths of stay.

Potential Impact of a Validated Screening Tool for Pediatric Abusive Head Trauma

OBJECTIVE

To conduct a retrospective, theoretical comparison of actual pediatric intensive care unit (PICU) screening for abusive head trauma (AHT) vs AHT screening guided by a previously validated 4-variable clinical prediction rule (CPR) in datasets used by the Pediatric Brain Injury Research Network to derive and validate the CPR.

STUDY DESIGN

We calculated CPR-based estimates of abuse probability for all 500 patients in the datasets. Next, we demonstrated a positive and very strong correlation between these estimates of abuse probability and the overall diagnostic yields of our patients' completed skeletal surveys and retinal examinations. Having demonstrated this correlation, we applied mean estimates of abuse probability to predict additional, positive abuse evaluations among patients lacking skeletal survey and/or retinal examination. Finally, we used these predictions of additional, positive abuse evaluations to extrapolate and compare AHT detection (and 2 other measures of AHT screening accuracy) in actual PICU screening for AHT vs AHT screening guided by the CPR.

RESULTS

Our results suggest that AHT screening guided by the CPR could theoretically increase AHT detection in PICU settings from 87%-96% (P < .001), and increase the overall diagnostic yield of completed abuse evaluations from 49%-56% (P = .058), while targeting slightly fewer, though not significantly less, children for abuse evaluation.

CONCLUSIONS

Applied accurately and consistently, the recently validated, 4-variable CPR could theoretically improve the accuracy of AHT screening in PICU settings.

Relationship of ECMO duration with outcomes after pediatric cardiac surgery: a multi-institutional analysis

BACKGROUND

There are very sparse data on the outcomes of children receiving prolonged extracorporeal membrane oxygenation (ECMO) after cardiac surgery. This study was aimed to evaluate the association of ECMO duration with outcomes in children undergoing surgery for congenital heart disease using the Pediatric Health Information System (PHIS) database.

METHODS

Patients aged ≤18 years receiving ECMO after pediatric cardiac surgery (with or without cardiopulmonary bypass) at a PHIS-participating hospital (2004-2013) were included. De-identified data obtained from retrospective, observational dataset included demographic information, baseline characteristics, pre-ECMO risk factors, operation details, patient diagnoses, and center data. Outcomes evaluated included in-hospital mortality, length of mechanical ventilation, length of ICU stay, length of hospital stay, and hospital charges. Cox proportional hazards models were fitted to study the probability of study outcomes as a function of ECMO duration.

RESULTS

Nine hundred ninety-eight patients from 37 hospitals qualified for inclusion. The median duration of ECMO run was 4 days (IQR: 1.7). After adjusting for patient and center characteristics, there was 12% increase in the odds of mortality for every 24 hours increase in ECMO duration (OR: 1.12, 95% CI: 1.07-1.18, P<0.001). Patients receiving longer duration of ECMO were associated with longer length of mechanical ventilation, longer length of ICU stay, longer length of hospital stay, and higher hospital charges.

CONCLUSION

Data from this large multicenter database suggest that longer duration of ECMO support after pediatric cardiac surgery is associated with worsening outcomes.

Twitter as a tool for communication and knowledge exchange in academic medicine: A guide for skeptics and novices

Twitter is a tool for physicians to increase engagement of learners and the public, share scientific information, crowdsource new ideas, conduct, discuss and challenge emerging research, pursue professional development and continuing medical education, expand networks around specialized topics and provide moral support to colleagues. However, new users or skeptics may well be wary of its potential pitfalls. The aims of this commentary are to discuss the potential advantages of the Twitter platform for dialogue among physicians, to explore the barriers to accurate and high-quality healthcare discourse and, finally, to recommend potential safeguards physicians may employ against these threats in order to participate productively.

Validation of a clinical prediction rule for pediatric abusive head trauma

BACKGROUND AND OBJECTIVE

To reduce missed cases of pediatric abusive head trauma (AHT), Pediatric Brain Injury Research Network investigators derived a 4-variable AHT clinical prediction rule (CPR) with sensitivity of .96. Our objective was to validate the screening performance of this AHT CPR in a new, equivalent patient population.

METHODS

We conducted a prospective, multicenter, observational, cross-sectional study. Applying the same inclusion criteria, definitional criteria for AHT, and methods used in the completed derivation study, Pediatric Brain Injury Research Network investigators captured complete clinical, historical, and radiologic data on 291 acutely head-injured children <3 years of age admitted to PICUs at 14 participating sites, sorted them into comparison groups of abusive and nonabusive head trauma, and measured the screening performance of the AHT CPR.

RESULTS

In this new patient population, the 4-variable AHT CPR demonstrated sensitivity of .96, specificity of .46, positive predictive value of .55, negative predictive value of .93, positive likelihood ratio of 1.67, and negative likelihood ratio of 0.09. Secondary analysis revealed that the AHT CPR identified 98% of study patients who were ultimately diagnosed with AHT.

CONCLUSIONS

Four readily available variables (acute respiratory compromise before admission; bruising of the torso, ears, or neck; bilateral or interhemispheric subdural hemorrhages or collections; and any skull fractures other than an isolated, unilateral, nondiastatic, linear, parietal fracture) identify AHT with high sensitivity in young, acutely head-injured children admitted to the PICU.

Factors associated with disease severity in children with bronchiolitis

OBJECTIVE

Bronchiolitis is one of the top causes of hospitalization of infants in the United States. Several clinical factors have been associated with hospitalization; however, few studies have examined factors related to severe disease. Our goal was to describe the clinical characteristics and hospital course of children admitted with bronchiolitis and to identify factors related to intensive care unit (ICU) admission in this population.

METHODS

We conducted a retrospective review of all children less than 2 years of age admitted to a children's hospital with bronchiolitis between July 2008 and July 2011. Demographic and clinical data were collected including information regarding hospital course, treatments received and respiratory pathogens.

RESULTS

During the study period, 734 children were admitted to the hospital with bronchiolitis, 22% of whom were admitted to the ICU and 10% of whom were intubated and mechanically ventilated. Admission to the ICU was associated with younger age [110 (45-210) days versus 69 (35-149) days, p < 0.001] and history of premature birth (OR 1.7, 95% CI 1.1-2.4, p = 0.01), but not with race or ethnicity. The use of respiratory treatments was common in the children admitted to the ICU but was not associated with shortened durations of hospitalization. In addition, neither prematurity nor young age were associated with either increased duration of hospitalization or with increased likelihood of mechanical ventilation.

CONCLUSIONS

During acute bronchiolitis infections, younger children and those with a history of prematurity were more likely to be admitted to the ICU with severe disease.

Association of center volume with outcomes in critically ill children with acute asthma

BACKGROUND

Little is known about the relation between center volume and outcomes in children requiring intensive care unit (ICU) admission for acute asthma.

OBJECTIVE

To evaluate the association of center volume with the odds of receiving positive pressure ventilation and length of ICU stay.

METHODS

Patients 2 to 18 years of age with the primary diagnosis of asthma were included (2009-2012). Center volume was defined as the average number of mechanical ventilator cases per year for any diagnoses during the study period. In multivariable analysis, the odds of receiving positive pressure ventilation (invasive and noninvasive ventilation) and ICU length of stay were evaluated as a function of center volume.

RESULTS

Fifteen thousand eighty-three patients from 103 pediatric ICUs with the primary diagnosis of acute asthma met the inclusion criteria. Seven hundred fifty-two patients (5%) received conventional mechanical ventilation and 964 patients (6%) received noninvasive ventilation. In multivariable analysis, center volume was not associated with the odds of receiving any form of positive pressure ventilation in children with acute asthma, with the exception of high- to medium-volume centers. However, ICU length of stay varied with center volume and was noted to be longer in low-volume centers compared with medium- and high-volume centers.

CONCLUSION

In children with acute asthma, this study establishes a relation between center volume and ICU length of stay. However, this study fails to show any significant relation between center volume and the odds of receiving positive pressure ventilation; further analyses are needed to evaluate this relation in more detail.

Duration of Cardiopulmonary Resuscitation and Illness Category Impact Survival and Neurologic Outcomes for In-hospital Pediatric Cardiac Arrests

Background—

Pediatric cardiopulmonary resuscitation (CPR) for >20 minutes has been considered futile after pediatric in-hospital cardiac arrests. This concept has recently been questioned, although the effect of CPR duration on outcomes has not recently been described. Our objective was to determine the relationship between CPR duration and outcomes after pediatric in-hospital cardiac arrests.

Methods and Results—

We examined the effect of CPR duration for pediatric in-hospital cardiac arrests from the Get With The Guidelines–Resuscitation prospective, multicenter registry of in-hospital cardiac arrests. We included 3419 children from 328 US and Canadian Get With The Guidelines–Resuscitation sites with an in-hospital cardiac arrest between January 2000 and December 2009. Patients were stratified into 5 patient illness categories: surgical cardiac, medical cardiac, general medical, general surgical, and trauma. Survival to discharge was 27.9%, but only 19.0% of all cardiac arrest patients had favorable neurological outcomes. Between 1 and 15 minutes of CPR, survival decreased linearly by 2.1% per minute, and rates of favorable neurological outcome decreased by 1.2% per minute. Adjusted probability of survival was 41% for CPR duration of 1 to 15 minutes and 12% for >35 minutes. Among survivors, favorable neurological outcome occurred in 70% undergoing <15 minutes of CPR and 60% undergoing CPR >35 minutes. Compared with general medical patients, surgical cardiac patients had the highest adjusted odds ratios for survival and favorable neurological outcomes, 2.5 (95% confidence interval, 1.8–3.4) and 2.7 (95% confidence interval, 2.0–3.9), respectively.

Conclusions—

CPR duration was independently associated with survival to hospital discharge and neurological outcome. Among survivors, neurological outcome was favorable for the majority of patients. Performing CPR for >20 minutes is not futile in some patient illness categories.

β2-adrenergic receptor haplotype linked to intubation and mechanical ventilation in children with asthma

BACKGROUND AND AIMS

Children with asthma and respiratory failure comprise a small but significant subset of children with acute asthma. In addition to clinical and historical factors that have been associated with respiratory failure, there may also be genetic factors that predispose some asthmatic children to intubation and mechanical ventilation. However, this has not previously been assessed in this population. We hypothesized that genetic polymorphisms of the β(2)-adrenergic receptor (ADRβ(2)) are associated with intubation and mechanical ventilation in children with asthma.

MATERIALS AND METHODS

We performed genotyping of the ADRβ(2) in a pooled cohort of 104 children admitted to the intensive care unit (ICU) with a severe asthma exacerbation between 2002 and 2008. Genotype of the ADRβ(2) was compared with intubation for respiratory failure.

RESULTS

At amino acid position 16, 33% (n = 34) of children were homozygous for the glycine allele (Gly16Gly), 15% (n = 16) were homozygous for the arginine allele (Arg16Arg), and 52% (n = 54) were heterozygous (Arg16Gly). At amino acid position 27, 54% (n = 56) of children were homozygous for the glutamine allele (Gln27Gln), 8% (n = 8) were homozygous for the glutamic acid allele (Glu27Glu), and 38% (n = 40) were heterozygous (Gln27Glu). The haplotypes at these positions were Arg16Gly-Gln27Gln (29%, n = 30), Arg16Gly-Gln27Glu (22%, n = 23), Gly16Gly-Gln27Glu (16%, n = 17), Arg16Arg-Gln27Gln (16%, n = 17), Gly16Gly-Gln27Gln (9%, n = 9), and Gly16Gly-Glu27Glu (8%, n = 8). Twelve children in this cohort were intubated for respiratory failure. Intubation was not associated with age, obesity, race/ethnicity, or NHBLI asthma classification. However, children with the Arg16Gly-Gln27Gln haplotype were significantly more likely to be intubated and mechanical ventilated (OR = 4.2; 95% CI = 1.2-14.5; p = .036) than children with other haplotypes of the ADRβ(2). When examining the subset of intubated children, those with the Arg16Gly-Gln27Gln haplotype trended towards longer ICU length of stay (329 ± 270 vs. 124 ± 57 hours; p = .09), but this was not statistically significant.

CONCLUSIONS

Children with the Arg16Gly-Gln27Gln haplotype of the ADRβ(2) were four times more likely to be intubated and mechanically ventilated during severe asthma exacerbations. Genetic factors may influence the development of a more severe asthma phenotype during acute exacerbations.

Pulmonary mechanics following albuterol therapy in mechanically ventilated infants with bronchiolitis

BACKGROUND AND AIMS

Bronchiolitis is a common cause of critical illness in infants. Inhaled β(2)-agonist bronchodilators are frequently used as part of treatment, despite unproven effectiveness. The purpose of this study was to describe the physiologic response to these medications in infants intubated and mechanically ventilated for bronchiolitis.

MATERIALS AND METHODS

We conducted a prospective trial of albuterol treatment in infants intubated and mechanically ventilated for bronchiolitis. Before and for 30 minutes following inhaled albuterol treatment, sequential assessments of pulmonary mechanics were determined using the interrupter technique on repeated consecutive breaths.

RESULTS

Fifty-four infants were enrolled. The median age was 44 days (25-75%; interquartile range (IQR) 29-74 days), mean hospital length of stay (LOS) was 18.3 ± 13.3 days, mean ICU LOS was 11.3 ± 6.4 days, and mean duration of mechanical ventilation was 8.5 ± 3.5 days. Fifty percent (n = 27) of the infants were male, 81% (n = 44) had public insurance, 80% (n = 41) were Caucasian, and 39% (n = 21) were Hispanic. Fourteen of the 54 (26%) had reduction in respiratory system resistance (Rrs) that was more than 30% below baseline, and were defined as responders to albuterol. Response to albuterol was not associated with demographic factors or hospitalization outcomes such as LOS or duration of mechanical ventilation. However, increased Rrs, prematurity, and non-Hispanic ethnicity were associated with increased LOS.

CONCLUSIONS

In this population of mechanically ventilated infants with bronchiolitis, relatively few had a reduction in pulmonary resistance in response to inhaled albuterol therapy. This response was not associated with improvements in outcomes.

Beta-adrenergic receptor polymorphisms associated with length of ICU stay in pediatric status asthmaticus

BACKGROUND

During severe exacerbations, asthmatic children vary significantly in their response to high-dose continuous β(2) -adrenergic receptor (ADRβ(2) ) agonist therapy. Genetic polymorphisms have been identified within the ADRβ(2) that may be functionally relevant, but few studies have been performed in this population. Our hypothesis was that genotypic differences are associated with magnitude of response to ADRβ(2) agonist treatment during severe asthma exacerbations in children.

METHODS

Children aged 2-18 years admitted to the ICU (intensive care unit) with a severe asthma exacerbation between 2006 and 2008 were eligible. Genotyping of the ADRβ(2) was performed.

RESULTS

Eighty-nine children consented and were enrolled. Despite similar clinical asthma scores on admission, children with the Gly(16) Gly genotype at amino acid position 16 had significantly shorter ICU length of stay (LOS) and hospital LOS, compared to children with Arg(16) Arg and Arg(16) Gly genotypes. Children with either the Gln(27) Glu or Glu(27) Glu genotype at amino acid position 27 also had significantly shorter ICU LOS and hospital LOS compared to children with the Gln(27) Gln genotype. The Arg(16) Gly-Gln(27) Gln haplotype was associated with the longest ICU LOS, but this was not statistically different from other haplotypes.

CONCLUSIONS

In this cohort of children with severe asthma exacerbations, ADRβ(2) polymorphisms were associated with responses to therapy. Knowledge of the genetic profile of children with asthma may allow for targeted therapy during acute exacerbations.

Synthesis of the dysiherbaine tetrahydropyran core utilizing improved tethered aminohydroxylation conditions

A concise stereoselective route to the dysiherbaine tetrahydropyran core was achieved in 9 steps and 39% overall yield. Donohoe's improved tethered aminohydroxylation conditions were employed to concurrently install the amino and alcohol groups and construct the tetrahydropyran ring, which features four contiguous cis-stereocenters.

Factors associated with the development of severe asthma exacerbations in children

BACKGROUND

Asthma exacerbations are one of the most common causes of hospitalization in children and account for approximately 10,000 intensive care unit (ICU) admissions per year in the United States. Despite the prevalence of this disease in children, the factors associated with the development of these severe exacerbations are largely unknown.

METHODS

A retrospective case-control study was conducted involving all eligible children admitted to the hospital with asthma for a 1-year period. Potential associated factors and outcomes of children admitted to the ICU with a severe exacerbation (cases) were compared to those of children with acute asthma admitted to the ward (controls).

RESULTS

A total of 188 children were hospitalized with asthma during the study period, 57 (30%) of whom required admission to the ICU. There were no differences in age, gender, or race between cases and controls. Children admitted to the ICU were significantly more likely to have an allergy or irritant-triggered exacerbation than children admitted to the ward (OR 3.9; 95% CI 1.9-8.2; p = .0003). Additionally, children in the ICU had a significantly shorter duration of illness before being admitted to the hospital compared to those admitted to the ward (1.7 ± 2.3 vs. 3.4 ± 4.8 days; p = .002).

CONCLUSIONS

In this retrospective review, severe asthma exacerbations in children are associated with a more rapid onset of symptoms and are more likely to be associated with allergens or irritants, supporting the importance of atopy in this population.