A Novel Macrophage Subpopulation Conveys Increased Genetic Risk of Coronary Artery Disease.

BACKGROUND: Coronary artery disease (CAD), the leading cause of death worldwide, is influenced by both environmental and genetic factors. Although over 250 genetic risk loci have been identified through genome-wide association studies, the specific causal variants and their regulatory mechanisms are still largely unknown, particularly in disease-relevant cell types such as macrophages. METHODS: We utilized single-cell RNA-seq and single-cell multiomics approaches in primary human monocyte-derived macrophages to explore the transcriptional regulatory network involved in a critical pathogenic event of coronary atherosclerosis-the formation of lipid-laden foam cells. The relative genetic contribution to CAD was assessed by partitioning disease heritability across different macrophage subpopulations. Meta-analysis of single-cell RNA-seq data sets from 38 human atherosclerotic samples was conducted to provide high-resolution cross-referencing to macrophage subpopulations in vivo. RESULTS: We identified 18 782 cis-regulatory elements by jointly profiling the gene expression and chromatin accessibility of >5000 macrophages. Integration with CAD genome-wide association study data prioritized 121 CAD-related genetic variants and 56 candidate causal genes. We showed that CAD heritability was not uniformly distributed and was particularly enriched in the gene programs of a novel CD52-hi lipid-handling macrophage subpopulation. These CD52-hi macrophages displayed significantly less lipoprotein accumulation and were also found in human atherosclerotic plaques. We investigated the cis-regulatory effect of a risk variant rs10488763 on FDX1, implicating the recruitment of AP-1 and C/EBP-ß in the causal mechanisms at this locus. CONCLUSIONS: Our results provide genetic evidence of the divergent roles of macrophage subsets in atherogenesis and highlight lipid-handling macrophages as a key subpopulation through which genetic variants operate to influence disease. These findings provide an unbiased framework for functional fine-mapping of genome-wide association study results using single-cell multiomics and offer new insights into the genotype-environment interactions underlying atherosclerotic disease.

DNA methylases for site-selective inhibition of type IIS restriction enzyme activity.

DNA methylases of the restriction-modifications (R-M) systems are promising enzymes for the development of novel molecular and synthetic biology tools. Their use in vitro enables the deployment of independent and controlled catalytic reactions. This work aimed to produce recombinant DNA methylases belonging to the R-M systems, capable of in vitro inhibition of the type IIS restriction enzymes BsaI, BpiI, or LguI. Non-switchable methylases are those whose recognition sequences fully overlap the recognition sequences of their associated endonuclease. In switch methylases, the methylase and endonuclease recognition sequences only partially overlap, allowing sequence engineering to alter methylation without altering restriction. In this work, ten methylases from type I and II R-M systems were selected for cloning and expression in E. coli strains tolerant to methylation. Isopropyl ß-D-1-thiogalactopyranoside (IPTG) concentrations and post-induction temperatures were tested to optimize the soluble methylases expression, which was achieved with 0.5 mM IPTG at 20 °C. The C-terminal His6-Tag versions showed better expression than the N-terminal tagged versions. DNA methylation was analyzed using purified methylases and custom test plasmids which, after the methylation reactions, were digested using the corresponding associated type IIS endonuclease. The non-switchable methylases M2.Eco31I, M2.BsaI, M2.HpyAII, and M1.MboII along with the switch methylases M.Osp807II and M2.NmeMC58II showed the best activity for site-selective inhibition of type IIS restriction enzyme activity. This work demonstrates that our recombinant methylases were able to block the activity of type IIS endonucleases in vitro, allowing them to be developed as valuable tools in synthetic biology and DNA assembly techniques. KEY POINTS: • Non-switchable methylases always inhibit the relevant type IIS endonuclease activity • Switch methylases inhibit the relevant type IIS endonuclease activity depending on the sequence engineering of their recognition site • Recombinant non-switchable and switch methylases were active in vitro and can be deployed as tools in synthetic biology and DNA assembly.

A Bayesian approach for two-stage multivariate Mendelian randomization with mixed outcomes.

Many research studies have investigated the relationship between baseline factors or exposures, such as patient demographic and disease characteristics, and study outcomes such as toxicities or quality of life, but results from most of these studies may be problematic because of potential confounding effects (eg, the imbalance in baseline factors or exposures). It is important to study whether the baseline factors or exposures have causal effects on the clinical outcomes, so that clinicians can have better understanding of the diseases and develop personalized medicine. Mendelian randomization (MR) provides an efficient way to estimate the causal effects using genetic instrumental variables to handle confounders, but most of the existing studies focus on a single outcome at a time and ignores the correlation structure of multiple outcomes. Given that clinical outcomes like toxicities and quality of life are usually a mixture of different types of variables, and multiple datasets may be available for such outcomes, it may be much more beneficial to analyze them jointly instead of separately. Some well-established methods are available for building multivariate models on mixed outcomes, but they do not incorporate MR mechanism to deal with the confounders. To overcome these challenges, we propose a Bayesian-based two-stage multivariate MR method for mixed outcomes on multiple datasets, called BMRMO. Using simulation studies and clinical applications on the CO.17 and CO.20 studies, we demonstrate better performance of our approach compared to the commonly used univariate two-stage method.

Biallelic Mutations in LRRC56, Encoding a Protein Associated with Intraflagellar Transport, Cause Mucociliary Clearance and Laterality Defects.

Primary defects in motile cilia result in dysfunction of the apparatus responsible for generating fluid flows. Defects in these mechanisms underlie disorders characterized by poor mucus clearance, resulting in susceptibility to chronic recurrent respiratory infections, often associated with infertility; laterality defects occur in about 50% of such individuals. Here we report biallelic variants in LRRC56 (known as oda8 in Chlamydomonas) identified in three unrelated families. The phenotype comprises laterality defects and chronic pulmonary infections. High-speed video microscopy of cultured epithelial cells from an affected individual showed severely dyskinetic cilia but no obvious ultra-structural abnormalities on routine transmission electron microscopy (TEM). Further investigation revealed that LRRC56 interacts with the intraflagellar transport (IFT) protein IFT88. The link with IFT was interrogated in Trypanosoma brucei. In this protist, LRRC56 is recruited to the cilium during axoneme construction, where it co-localizes with IFT trains and is required for the addition of dynein arms to the distal end of the flagellum. In T. brucei carrying LRRC56-null mutations, or a variant resulting in the p.Leu259Pro substitution corresponding to the p.Leu140Pro variant seen in one of the affected families, we observed abnormal ciliary beat patterns and an absence of outer dynein arms restricted to the distal portion of the axoneme. Together, our findings confirm that deleterious variants in LRRC56 result in a human disease and suggest that this protein has a likely role in dynein transport during cilia assembly that is evolutionarily important for cilia motility.

Clinical utility of NGS diagnosis and disease stratification in a multiethnic primary ciliary dyskinesia cohort.

BACKGROUND: Primary ciliary dyskinesia (PCD), a genetically heterogeneous condition enriched in some consanguineous populations, results from recessive mutations affecting cilia biogenesis and motility. Currently, diagnosis requires multiple expert tests. METHODS: The diagnostic utility of multigene panel next-generation sequencing (NGS) was evaluated in 161 unrelated families from multiple population ancestries. RESULTS: Most (82%) families had affected individuals with biallelic or hemizygous (75%) or single (7%) pathogenic causal alleles in known PCD genes. Loss-of-function alleles dominate (73% frameshift, stop-gain, splice site), most (58%) being homozygous, even in non-consanguineous families. Although 57% (88) of the total 155 diagnostic disease variants were novel, recurrent mutations and mutated genes were detected. These differed markedly between white European (52% of families carry DNAH5 or DNAH11 mutations), Arab (42% of families carry CCDC39 or CCDC40 mutations) and South Asian (single LRRC6 or CCDC103 mutations carried in 36% of families) patients, revealing a striking genetic stratification according to population of origin in PCD. Genetics facilitated successful diagnosis of 81% of families with normal or inconclusive ultrastructure and 67% missing prior ultrastructure results. CONCLUSIONS: This study shows the added value of high-throughput targeted NGS in expediting PCD diagnosis. Therefore, there is potential significant patient benefit in wider and/or earlier implementation of genetic screening.

Medical Oncologists' Perspectives on How the Results of the IDEA Collaboration Impact the Adjuvant Treatment of Stage III Colon Cancer.

BACKGROUND: The International Duration Evaluation of Adjuvant Chemotherapy (IDEA) collaboration aimed to evaluate whether 3 months of adjuvant chemotherapy are noninferior to 6 months. Our study objectives were to characterize medical oncologists' perspectives toward the results of the IDEA collaboration and to evaluate how IDEA impacted prescribing patterns of adjuvant FOLFOX and CAPOX in colon cancer. MATERIALS AND METHODS: A list of questions developed by four medical oncologists regarding IDEA results were formulated and distributed online to gastrointestinal medical oncologists globally. Descriptive statistics and chi-square tests were used to summarize information. RESULTS: Of 174 responses, 145 were complete and analyzed. Responses were obtained globally from South America (53%); the U.S. and Canada (28%); Europe, Australia, and New Zealand (12%); and Asia (7%). Most clinicians (98%) were aware of the IDEA study. Prior to IDEA, clinicians preferred FOLFOX over CAPOX (81% vs. 19%). Subsequent to IDEA, 55% of clinicians preferred CAPOX over FOLFOX (odds ratio, 5.0; 95% confidence interval, 3.0-8.5; p < .01 compared with pre-IDEA). Two thirds (68%) of responders tailored duration of adjuvant therapy based on risk stratification. Most oncologists (76%) were more willing to discontinue oxaliplatin early if toxicities develop after the results of IDEA. Half of responders (50%) found that IDEA increased their confidence in decision making for adjuvant treatment; 36% were unchanged, and 15% indicated decreased confidence. Less than half (48%) were comfortable communicating the study results and the concept of a noninferiority trial with patients. CONCLUSION: IDEA appears to have shifted clinician preference from FOLFOX to CAPOX for adjuvant therapy, and most clinicians now use a risk-stratified approach in determining duration of adjuvant therapy. Patient education resources may facilitate better communication of IDEA results to patients. IMPLICATIONS FOR PRACTICE: This global survey illustrates that most gastrointestinal medical oncologists now use a risk-stratified approach for determining the duration of adjuvant chemotherapy for stage III colon cancer. Clinicians are five times more likely to choose CAPOX over FOLFOX after the International Duration Evaluation of Adjuvant Chemotherapy (IDEA) collaboration results.

Advantages of the net benefit regression framework for trial-based economic evaluations of cancer treatments: an example from the Canadian Cancer Trials Group CO.17 trial.

BACKGROUND: Economic evaluations commonly accompany trials of new treatments or interventions; however, regression methods and their corresponding advantages for the analysis of cost-effectiveness data are not widely appreciated. METHODS: To illustrate regression-based economic evaluation, we review a cost-effectiveness analysis conducted by the Canadian Cancer Trials Group's Committee on Economic Analysis and implement net benefit regression. RESULTS: Net benefit regression offers a simple option for cost-effectiveness analyses of person-level data. By placing economic evaluation in a regression framework, regression-based techniques can facilitate the analysis and provide simple solutions to commonly encountered challenges (e.g., the need to adjust for potential confounders, identify key patient subgroups, and/or summarize "challenging" findings, like when a more effective regimen has the potential to be cost-saving). CONCLUSIONS: Economic evaluations of patient-level data (e.g., from a clinical trial) can use net benefit regression to facilitate analysis and enhance results.

Pilot study of the ability to probabilistically link clinical trial patients to administrative data and determine long-term outcomes.

BACKGROUND: Clinical trials are important but extremely costly. Utilization of routinely collected administrative data may simplify and enhance clinical trial data collection. PURPOSE: The aim of this study was to test the feasibility of use of administrative databases in Ontario, Canada, for long-term clinical trial follow-up, specifically (a) to determine whether limited patient identifiers held by the Canadian Cancer Trials Group can be used to probabilistically link with individuals in the Institute for Clinical Evaluative Sciences databases and if so, (b) the level of concordance between the two data sets. METHODS: This retrospective study was conducted through collaboration of established health service (Institute for Clinical Evaluative Sciences) and clinical trial (Canadian Cancer Trials Group) research groups in the province of Ontario, Canada, where healthcare is predominantly funded by the government. Adults with pre-treated metastatic colorectal cancer previously enrolled in the Canadian Cancer Trials Group CO.17 and CO.20 randomized phase III trials were included, limited to those in Ontario. The main outcomes were rate of successful probabilistic linkage and concordance of survival data, stated a priori. RESULTS: Probabilistic linkage was successful in 266/293 (90.8%) participants. In those patients for whom linkage was successful, the Canadian Cancer Trials Group (trial) and the Institute for Clinical Evaluative Sciences (administrative) data sets were concordant with regard to the occurrence of death during the period of clinical trial follow-up in 206/209 (98.6%). Death was recorded in the Institute for Clinical Evaluative Sciences, but not the Canadian Cancer Trials Group, for 57 cases, where the event occurred after the clinical trial cut-off dates. The recorded date of death matched closely between both databases. During the period of clinical trial conduct, administrative databases contained details of hospitalizations and emergency room visits not captured in the clinical trial electronic database. CONCLUSION: Prospective use of administrative data could enhance clinical trial data collection, both for long-term follow-up and resource utilization for economic analyses and do so less expensively than current primary data collection. Recording a unique identifier (e.g. health insurance number) in trial databases would allow deterministic linkage for all participants.

Systematic Review and Metaanalysis Comparing the Bias and Accuracy of the Modification of Diet in Renal Disease and Chronic Kidney Disease Epidemiology Collaboration Equations in Community-Based Populations.

BACKGROUND: The majority of patients with chronic kidney disease are diagnosed and monitored in primary care. Glomerular filtration rate (GFR) is a key marker of renal function, but direct measurement is invasive; in routine practice, equations are used for estimated GFR (eGFR) from serum creatinine. We systematically assessed bias and accuracy of commonly used eGFR equations in populations relevant to primary care. CONTENT: MEDLINE, EMBASE, and the Cochrane Library were searched for studies comparing measured GFR (mGFR) with eGFR in adult populations comparable to primary care and reporting both the Modification of Diet in Renal Disease (MDRD) and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations based on standardized creatinine measurements. We pooled data on mean bias (difference between eGFR and mGFR) and on mean accuracy (proportion of eGFR within 30% of mGFR) using a random-effects inverse-variance weighted metaanalysis. We included 48 studies of 26875 patients that reported data on bias and/or accuracy. Metaanalysis of within-study comparisons in which both formulae were tested on the same patient cohorts using isotope dilution-mass spectrometry-traceable creatinine showed a lower mean bias in eGFR using CKD-EPI of 2.2 mL/min/1.73 m2 (95% CI, 1.1-3.2; 30 studies; I2 = 74.4%) and a higher mean accuracy of CKD-EPI of 2.7% (1.6-3.8; 47 studies; I2 = 55.5%). Metaregression showed that in both equations bias and accuracy favored the CKD-EPI equation at higher mGFR values. SUMMARY: Both equations underestimated mGFR, but CKD-EPI gave more accurate estimates of GFR.

Ciliated conical epithelial cell protrusions point towards a diagnosis of primary ciliary dyskinesia.

BACKGROUND: Primary ciliary dyskinesia can result from a number of different ciliary defects that adversely affect ciliary function resulting markedly reduced or absent mucociliary clearance. Improvement in diagnostic testing is an area of current research. During diagnostic evaluation of PCD we observed ciliated conical protrusions from part of the apical surface of ciliated cells in those diagnosed with PCD. The aim of this study was to investigate if this abnormality was specific to PCD. METHODS: Epithelial edges from 67 consecutively diagnosed PCD patients, 67 patients consecutively referred for PCD diagnostic testing in whom PCD was excluded, 22 with asthma and 18 with Cystic Fibrosis (CF) were studied retrospectively in a blinded manner using light microscopy. RESULTS: Forty six out of 67 patients with PCD had ciliated conical epithelial protrusions, whereas none were seen in patients where PCD was excluded, or in patients with asthma or CF. The sensitivity, specificity, positive predictive value and negative predictive value for the presence of the ciliated conical protrusions to predict a diagnosis of PCD were 76.5, 100, 100 and 77% respectively. CONCLUSIONS: Characteristic ciliated conical protrusions from ciliated epithelial cells maybe a useful pointer to the diagnosis of PCD. However, their absence does not exclude the diagnosis of PCD.

Mouse podoplanin supports adhesion and aggregation of platelets under arterial shear: A novel mechanism of haemostasis.

The podoplanin-CLEC-2 axis is critical in mice for prevention of hemorrhage in the cerebral vasculature during mid-gestation. This raises the question as to how platelets are captured by podoplanin on neuroepithelial cells in a high shear environment. In this study, we demonstrate that mouse platelets form stable aggregates on mouse podoplanin at arterial shear through a CLEC-2 and Src kinase-dependent pathway. Adhesion and aggregation are also dependent on the platelet glycoprotein (GP) receptors, integrin αIIbß3 and GPIb, and the feedback agonists ADP and thromboxane A2 (TxA2). CLEC-2 does not bind to von Willebrand factor (VWF) suggesting that the interaction with podoplanin is sufficient to both tether and activate platelets. Consistent with this, the surface plasmon resonance measurements reveal that mouse CLEC-2 binds to mouse podoplanin with nanomolar affinity. The present findings demonstrate a novel pathway of hemostasis in which podoplanin supports platelet capture and activation at arteriolar rates of shear.

Cardiovascular autonomic dysfunction in Ehlers-Danlos syndrome-Hypermobile type.

Autonomic dysfunction contributes to health-related impairment of quality of life in the hypermobile type of Ehlers-Danlos syndrome (hEDS). Typical signs and symptoms include tachycardia, hypotension, gastrointestinal dysmotility, and disturbed bladder function and sweating regulation. Cardiovascular autonomic dysfunction may present as Orthostatic Intolerance, Orthostatic Hypotension, Postural Orthostatic Tachycardia Syndrome, or Neurally Mediated Hypotension. The incidence, prevalence, and natural history of these conditions remain unquantified, but observations from specialist clinics suggest they are frequently seen in hEDS. There is growing understanding of how hEDS-related physical and physiological pathology contributes to the development of these conditions. Evaluation of cardiovascular symptoms in hEDS should include a careful history and clinical examination. Tests of cardiovascular function range from clinic room observation to tilt-table assessment to other laboratory investigations such as supine and standing catecholamine levels. Non-pharmacologic treatments include education, managing the environment to reduce exposure to triggers, improving cardiovascular fitness, and maintaining hydration. Although there are limited clinical trials, the response to drug treatments in hEDS is supported by evidence from case and cohort observational data, and short-term physiological studies. Pharmacologic therapy is indicated for patients with moderate-severe impairment of daily function and who have inadequate response or tolerance to conservative treatment. Treatment in hEDS often requires a focus on functional maintenance. Also, the negative impact of cardiovascular symptoms on physical and psycho-social well-being may generate a need for a more general evaluation and on-going management and support. © 2017 Wiley Periodicals, Inc.

Chronic fatigue in Ehlers-Danlos syndrome-Hypermobile type.

Chronic fatigue is an important contributor to impaired health-related quality of life in Ehlers-Danlos syndrome. There is overlap in the symptoms and findings of EDS and chronic fatigue syndrome. A proportion of those with CFS likely have EDS that has not been identified. The evaluation of chronic fatigue in EDS needs to include a careful clinical examination and laboratory testing to exclude common causes of fatigue including anemia, hypothyroidisim, and chronic infection, as well as dysfunction of major physiological or organ systems. Other problems that commonly contribute to fatigue in EDS include sleep disorders, chronic pain, deconditioning, cardiovascular autonomic dysfunction, bowel and bladder dysfunction, psychological issues, and nutritional deficiencies. While there is no specific pharmacological treatment for fatigue, many medications are effective for specific symptoms (such as headache, menstrual dysfunction, or myalgia) and for co-morbid conditions that result in fatigue, including orthostatic intolerance and insomnia. Comprehensive treatment of fatigue needs to also evaluate for biomechanical problems that are common in EDS, and usually involves skilled physical therapy and attention to methods to prevent deconditioning. In addition to managing specific symptoms, treatment of fatigue in EDS also needs to focus on maintaining function and providing social, physical, and nutritional support, as well as providing on-going medical evaluation of new problems and review of new evidence about proposed treatments. © 2017 Wiley Periodicals, Inc.

Evidence of Respiratory Syncytial Virus Spread by Aerosol. Time to Revisit Infection Control Strategies?

RATIONALE: Respiratory syncytial virus (RSV) is a highly contagious pathogen with a huge global health impact. It is a major cause of hospital-acquired infection; a large number of those exposed develop infection. Those infected in hospital are at increased risk of a severe clinical course. Prevention of nosocomial spread currently focuses on spread by hand and large droplets. There is little research evidence to determine if aerosol spread of infectious RSV is possible. OBJECTIVES: To determine if the air surrounding infants with RSV-positive bronchiolitis contains RSV in aerosolized particles that remain capable of causing infection. METHODS: The amount of RSV contained in aerosolized particles produced by infants with bronchiolitis due to RSV was measured using viable impactor sampling. The ability of RSV contained in these particles to infect healthy and chronic obstructive pulmonary disease (COPD) human ciliated respiratory epithelium was determined. RESULTS: We showed for the first time that infants with RSV-positive bronchiolitis nursed in a ward setting or ventilated in intensive care produced large numbers of aerosol particles containing RSV that remained infectious and were capable of infecting healthy and COPD human ciliated epithelium. A significant amount of RSV was found in particles with aerodynamic diameters less than 5 µm. CONCLUSIONS: Many of the aerosolized particles that contained RSV in the air surrounding infants with bronchiolitis were sufficiently small to remain airborne for a significant length of time and small enough to be inhaled and deposited throughout the respiratory tract. It is likely that this leads to spread of infection to others, with dissemination of infection throughout the respiratory tract.

Activation of glycoprotein VI (GPVI) and C-type lectin-like receptor-2 (CLEC-2) underlies platelet activation by diesel exhaust particles and other charged/hydrophobic ligands.

Platelets are activated by a range of stimuli that share little or no resemblance in structure to each other or to recognized ligands, including diesel exhaust particles (DEP), small peptides [4N1-1, Champs (computed helical anti-membrane proteins), LSARLAF (Leu-Ser-Ala-Arg-Leu-Ala-Phe)], proteins (histones) and large polysaccharides (fucoidan, dextran sulfate). This miscellaneous group stimulate aggregation of human and mouse platelets through the glycoprotein VI (GPVI)-FcR γ-chain complex and/or C-type lectin-like receptor-2 (CLEC-2) as shown using platelets from mice deficient in either or both of these receptors. In addition, all of these ligands stimulate tyrosine phosphorylation in GPVI/CLEC-2-double-deficient platelets, indicating that they bind to additional surface receptors, although only in the case of dextran sulfate does this lead to activation. DEP, fucoidan and dextran sulfate, but not the other agonists, activate GPVI and CLEC-2 in transfected cell lines as shown using a sensitive reporter assay confirming a direct interaction with the two receptors. We conclude that this miscellaneous group of ligands bind to multiple proteins on the cell surface including GPVI and/or CLEC-2, inducing activation. These results have pathophysiological significance in a variety of conditions that involve exposure to activating charged/hydrophobic agents.

Ciliary dyskinesia is an early feature of respiratory syncytial virus infection.

Respiratory syncytial virus is a major cause of respiratory disease. There are conflicting accounts of the response of human epithelial cells to respiratory syncytial virus and a lack of data on its effect on ciliary function. Our aim was to study the early stages of respiratory syncytial virus infection of primary human basal and ciliated cultures. Using high speed videomicroscopy, we found that ciliary beat frequency was unaffected by respiratory syncytial virus infection over 72 h; however, ciliary dyskinesia significantly increased within 24 h of infection (p<0.05). Transmission electron microscopy revealed that ultrastructural abnormalities were confined to ciliated cells, including increased cilia loss and mitochondrial damage. Confocal immunofluorescence microscopy showed that respiratory syncytial virus antigen gradually spread from the cell surface to the ciliary tip of infected cells over 3 days. Interestingly, ciliated cultures secreted fewer viruses than basal (progenitor) cell cultures and produced a chemokine response focused on recruitment of neutrophils. This study highlights differences in infection models and underscores the need to explore further the role of ciliated cells in the establishment of respiratory syncytial virus infection. Increased ciliary dyskinesia combined with ciliary loss and epithelial damage is likely to result in reduced mucociliary clearance early in the infective process.

The relationship between rash, tumour KRAS mutation status and clinical and quality of life outcomes in patients with advanced colorectal cancer treated with cetuximab in the NCIC CTG/AGITG CO.17.

BACKGROUND: The NCIC CTG/AGITG CO.17 trial demonstrated that cetuximab monotherapy improved overall and progression-free survival (OS and PFS) in patients previously treated for advanced colorectal cancer. A strong relationship was observed between benefit from cetuximab and development of rash. In this analysis, the association of rash and benefit from cetuximab is explored and presented by KRAS mutation status. MATERIAL AND METHODS: Rash was graded by NCI CTC 2.0 criteria. Landmark analysis was performed by excluding patients who died or dropped out within 28 days and then grouping by worst grade of rash experienced by day 28. Multivariate Cox models were conducted separately for patients with KRAS wild-type (WT) tumours and KRAS mutated (MUT) tumours. CO.17 primary outcome was OS. RESULTS: Development of grade 2 + rash on cetuximab was associated with a trend towards increased OS (HR 0.61 with 95% CI 0.36-1.02 and p = 0.06) and PFS (HR 0.68 with 95% CI 0.45-1.03 and p = 0.07) as compared to grade 0/1 rash in patients with WT tumours. In patients with WT tumours on cetuximab both grade 0/1 and grade 2 + rash were associated with increased PFS (HR 0.57 95% CI 0.38-0.86; p = 0.008; and HR 0.32 95% CI 0.21-0.49; p < 0.0001) respectively, in comparison with best supportive care (BSC). Only development of grade 2 + rash on cetuximab was associated with increased OS (HR 0.52 with 95% CI 0.34-0.80 and p = 0.003) in comparison with BSC. No significant difference was found in OS or PFS among patients on cetuximab with MUT tumours with either rash grade as compared to BSC. No consistent trend was observed for the association of severity of rash and quality of life (QoL). CONCLUSION: As all patients with WT tumours benefitted to some extent from cetuximab regardless of the grade of rash, grade of rash was not a useful predictive marker.

Nebulization of corticosteroids to asthmatic children: large variation in dose inhaled.

BACKGROUND AND OBJECTIVE: Despite problems associated with assessing the clinical effect and side effects of nebulized corticosteroids, little is known of the amount of drug that is inhaled by children with asthma or how this is affected by different drug formulations. The aim of this study was to test the hypothesis that children with asthma inhale the same proportion of the prescribed dose of nebulized fluticasone, beclomethasone dipropionate (BDP) and flunisolide. METHODS: The amount of nebulized drug that would have been inhaled by asthmatic children was captured on filters between the patient and nebulizer, and the amount contained in particles likely to reach the lung (i.e. <5 µm) is determined. RESULTS: The children studied would have inhaled 13% of the prescribed dose of fluticasone propionate, 21% of BDP and 25% of flunisolide. However, the percentage of the dose inhaled that was contained in particles <5 µm, and therefore more likely to reach the lungs, was only 5% of the prescribed dose of fluticasone propionate, 8% for BDP and 16% for flunisolide. The inter-subject variation coefficient of the dose inhaled was much greater for suspensions of fluticasone propionate (34%) and BDP (45%) than for suspensions of flunisolide solution (9%). CONCLUSIONS: Our results demonstrate that the prescribed dose may bear little resemblance to the dose delivered from a nebulizer and that the dose inhaled is significantly affected by the drug formulation prescribed.

Plasma versus tissue tumor mutational burden as biomarkers of durvalumab plus tremelimumab response in patients with metastatic colorectal cancer in the CO.26 trial.

PURPOSE: Tissue derived tumor mutation burden (TMB) of ≥10 mutations/Mb is a histology agnostic biomarker for the immune checkpoint inhibitor (ICI) pembrolizumab. However, the dataset on which this was validated lacked colorectal cancers (CRCs), and there is limited evidence for immunotherapy benefit in CRC using this threshold. PATIENTS AND METHODS: CO.26 was a randomized phase II study of 180 patients comparing durvalumab and tremelimumab (D+T, n=119 patients) versus best supportive care (BSC, n=61 patients). ctDNA sequencing was available for 168 patients (n=118 D+T, n=50), of which 165 had evaluable plasma TMB (pTMB). Tissue sequencing was available for 108 patients. Optimal thresholds for stratifying patients based on overall survival were determined using a minimal p-value approach. This report includes the final overall survival analysis. RESULTS: Tissue TMB ≥10 mutations/Mb was not predictive of benefit from D+T compared to BSC in microsatellite stable (MSS) metastatic CRC (HR 0.71 [95% CI:0.28-1.80], p=0.47). No tissue TMB threshold could identify a high TMB group that benefited from ICI. In contrast, plasma TMB (pTMB) ≥28 mutations/Mb was predictive of benefit from D+T (HR=0.34 [95%CI:0.13-0.85], p=0.022), as was clonal pTMB ≥10.6 mutations/Mb (HR=0.10 [95%CI:0.014-0.79], p=0.029) and subclonal pTMB ≥25.9/Mb (HR=0.20 [95% CI:0.061-0.69], p=0.010). Higher pTMB was associated with length of time on cytotoxic agents (p=0.021) and prior anti-EGFR exposure (p=2.44x10-06). CONCLUSION: pTMB derived from either clonal or subclonal mutations may identify a group more likely to benefit from immunotherapy, though validation is required. Tissue TMB provided no predictive utility for immunotherapy in this trial.

Transverse Colon Primary Tumor Location as a Biomarker in Metastatic Colorectal Cancer: A Pooled Analysis of CCTG/AGITG CO.17 and CO.20 Randomized Clinical Trials.

PURPOSE: Sidedness is prognostic and predictive of anti-EGFR efficacy in metastatic colorectal cancer (mCRC). Transverse colon has been historically excluded from several analyses of sidedness and the optimal division between left- and right-sided colorectal cancer is unclear. We investigated transverse colon primary tumor location as a biomarker in mCRC. EXPERIMENTAL DESIGN: Pooled analysis of CCTG/AGITG CO.17 and CO.20 trials of cetuximab in chemotherapy-refractory mCRC. Outcomes of patients with RAS/BRAF wild-type (WT) mCRC from CO.17 and KRAS WT mCRC from CO.20 were analyzed according to location. RESULTS: A total of 553 patients were analyzed, 32 (5.8%) with cancers from the transverse, 101 (18.3%) from right, and 420 from (75.9%) left colon. Transverse mCRC failed to reach significant benefit from cetuximab versus best supportive care (BSC) for overall survival [OS; median, 5.9 vs. 2.1 months; HR, 0.63; 95% confidence interval (CI), 0.28-1.42; P=0.26] and progression-free survival (PFS; median, 1.8 vs. 1.3 months; HR, 0.57; 95% CI, 0.26-1.28; P=0.16). Analyzing exclusively patients randomized to cetuximab, right-sided and transverse had comparable outcomes for OS (median, 5.6 vs. 5.9 months; HR, 0.82; 95% CI, 0.50-1.34; P=0.43) and PFS (median, 1.9 vs. 1.8 months; HR, 0.78; 95% CI, 0.49-1.26; P=0.31). Patients with left-sided mCRC had superior outcomes with cetuximab compared with transverse for OS (median, 9.7 vs. 5.9 months; HR, 0.42; 95% CI, 0.27-0.67; P=0.0002) and PFS (median, 3.8 vs. 1.8 months; HR, 0,49; 95% CI, 0.31-0.76; P=0.001). Location was not prognostic in patients treated with BSC alone. CONCLUSIONS: Transverse mCRC has comparable prognostic and predictive features with right-sided mCRC.