Interpatient Variability Research Articles

Endoglin and squamous cell carcinomas.

Despite the fact that the role of endoglin on endothelial cells has been extensively described, its expression and biological role on (epithelial) cancer cells is still debatable. Especially its function on squamous cell carcinoma (SCC) cells is largely unknown. Therefore, we investigated SCC endoglin expression and function in three types of SCCs; head and neck (HNSCC), esophageal (ESCC) and vulvar (VSCC) cancers. Endoglin expression was evaluated in tumor specimens and 14 patient-derived cell lines. Next to being expressed on angiogenic endothelial cells, endoglin is selectively expressed by individual SCC cells in tumor nests. Patient derived HNSCC, ESCC and VSCC cell lines express varying levels of endoglin with high interpatient variation. To assess the function of endoglin in signaling of TGF-β ligands, endoglin was overexpressed or knocked out or the signaling was blocked using TRC105, an endoglin neutralizing antibody. The endoglin ligand BMP-9 induced strong phosphorylation of SMAD1 independent of expression of the type-I receptor ALK1. Interestingly, we observed that endoglin overexpression leads to strongly increased soluble endoglin levels, which in turn decreases BMP-9 signaling. On the functional level, endoglin, both in a ligand dependent and independent manner, did not influence proliferation or migration of the SCC cells. In conclusion, these data show endoglin expression on individual cells in the tumor nests in SCCs and a role for (soluble) endoglin in paracrine signaling, without directly affecting proliferation or migration in an autocrine manner.

Accuracy of 3D printed spine models for pre-surgical planning of complex adolescent idiopathic scoliosis (AIS) in spinal surgeries: a case series

Adolescent idiopathic scoliosis (AIS) is a noticeable spinal deformity in both adult and adolescent population. In majority of the cases, the gold standard of treatment is surgical intervention. Technological advancements in medical imaging and 3D printing have revolutionised the surgical planning and intraoperative decision making for surgeons in spinal surgery. However, its applicability for planning complex spinal surgeries is poorly documented with human subjects. The objective of this study is to evaluate the accuracy of 3D printed models for complex spinal deformities based on Cobb angles between 40° to 95°.This is a retrospective cohort study where, five CT scans of the patients with AIS were segmented and 3D printed for evaluating the accuracy. Consideration was given to the Inter-patient and acquisition apparatus variability of the CT-scan dataset to understand the effect on trueness and accuracy of the developed CAD models. The developed anatomical models were re-scanned for analysing quantitative surface deviation to assess the accuracy of 3D printed spinal models. Results show that the average of the root mean square error (RMSE) between the 3DP models and virtual models developed using CT scan of mean surface deviations for the five 3d printed models was found to be 0.5±0.07 mm. Based on the RMSE, it can be concluded that 3D printing based workflow is accurate enough to be used for presurgical planning for complex adolescent spinal deformities. Image acquisition and post processing parameters, type of 3D printing technology plays key role in acquiring required accuracy for surgical applications.

Characterization of neonatal and infant enterostomy fluids - part II: Drug solubility

Previous research revealed marked differences in the composition of intestinal fluids between infants and adults. To explore the impact on the solubilization of orally administered drugs, the present study assessed the solubility of five poorly water-soluble, lipophilic drugs in intestinal fluid pools from 19 infant enterostomy patients (infant HIF). For some but not all drugs, the average solubilizing capacity of infant HIF was similar to that of HIF obtained from adults (adult HIF) in fed conditions. Commonly used fed state simulated intestinal fluids (FeSSIF(-V2)) predicted fairly well drug solubility in the aqueous fraction of infant HIF, but did not account for the substantial solubilization by the lipid phase of infant HIF. Despite similarities in the average solubilities of some drugs in infant HIF and adult HIF or SIF, the underlying solubilization mechanisms likely differ, considering important compositional differences (e.g., low bile salt levels). Finally, the huge variability in composition of infant HIF pools resulted in a highly variable solubilizing capacity, potentially causing variations in drug bioavailability. The current study warrants future research focusing on (i) understanding the mechanisms underlying drug solubilization in infant HIF and (ii) evaluating the sensitivity of oral drug products to interpatient variations in drug solubilization.

EPEN-12. COMPARING CELLULAR HIERARCHIES AND SPATIAL ARCHITECTURE ACROSS MOLECULAR SUBGROUPS OF SUPRATENTORIAL EPENDYMOMAS

Abstract Ependymomas (EPN) are among the most common and fatal pediatric brain tumors with currently no targeted therapies available. Molecular studies including genome-wide DNA methylation profiling have shown that supratentorial ependymoma is subdivided into subgroups characterized by distinct fusion proteins: ZFTA-RELA fusion-positive (ZFTA-RELA), YAP1 fusion-positive (ST-YAP1), and four alternative ZFTA fusion-positive (ZFTA-Cluster 1, ZFTA-Cluster 2, ZFTA-Cluster 3, and ZFTA-Cluster 4). ZFTA-RELA tumors have been identified as the most common and aggressive molecular group with high intra-tumoral heterogeneity. However, limited sample size and interpatient variability in previous studies highlight a critical need for comprehensive profiling of supratentorial ependymomas across a larger patient cohort. In particular, how ZFTA-RELA compares to other subgroups of supratentorial ependymoma is unknown. Here, we collected and profiled 44 supratentorial patient tumors encompassing ZFTA-RELA (n=21), ZFTA-Cluster 1 (n=6), ZFTA-Cluster 2 (n=4), ZFTA-Cluster 3 (n=7), ZFTA-Cluster 4 (n=2), and ST-YAP1 (n=4). We profiled all tumors by single cell/single nucleus RNA-sequencing, and further characterized ZFTA-RELA by single cell spatial transcriptomics. Within each patient’s tumor we find multiple normal and aberrant differentiation trajectories from neural progenitor-like cells towards glial-like, mesenchymal-like and ependymal-like cells. Using sequencing-based lineage tracing, we experimentally validate these computationally inferred cellular hierarchies in vitro. Notably, compared to ZFTA-RELA ependymomas we observed predominantly higher proportion of early neural progenitor-like cells in ZFTA-Cluster 2 and ZFTA-Cluster 3, while in ST-YAP1 greater representation of mature ependymal-like cells. These findings highlight differences in developmental and aberrant differentiation trajectories driven by combination of oncogenic fusions and cell of origin in supratentorial ependymoma subgroups. In addition, neural progenitor-like cells most highly express ZFTA-fusions and are spatially distinct from other cell states, highlighting oncogenic fusions driving tumorigenesis organized in spatial niches. Together, this study reveals previously unknown intra- and intertumoral heterogeneity across subgroups of supratentorial ependymoma, as well as distinct cellular and spatial architecture.

Population Pharmacokinetic Analysis of Perampanel in Portuguese Patients Diagnosed with Refractory Epilepsy.

Perampanel is a promising antiepileptic drug (AED) for refractory epilepsy treatment due to its innovative mechanism of action. This study aimed to develop a population pharmacokinetic (PopPK) model to be further used in initial dose optimization of perampanel in patients diagnosed with refractory epilepsy. A total of seventy-two plasma concentrations of perampanel obtained from forty-four patients were analyzed through a population pharmacokinetic approach by means of nonlinear mixed effects modeling (NONMEM). A one-compartment model with first-order elimination best described the pharmacokinetic profiles of perampanel. Interpatient variability (IPV) was entered on clearance (CL), while the residual error (RE) was modeled as proportional. The presence of enzyme-inducing AEDs (EIAEDs) and body mass index (BMI) were found as significant covariates for CL and volume of distribution (V), respectively. The mean (relative standard error) estimates for CL and V of the final model were 0.419 L/h (5.56%) and 29.50 (6.41%), respectively. IPV was 30.84% and the proportional RE was 6.44%. Internal validation demonstrated an acceptable predictive performance of the final model. A reliable population pharmacokinetic model was successfully developed, and it is the first enrolling real-life adults diagnosed with refractory epilepsy.

Partitioning for Easy Multiplexing: A Versatile Droplet PCR Application for Clone Monitoring in Tumors

Clinical genome-wide next-generation sequencing (NGS) has brought new challenges to genetic laboratories. The identification of numerous patient-specific variants that may require to be screened for on multiple other samples poses an issue when striving for time and cost-effectiveness. Here, we propose d-multiSeq, a straightforward method utilizing the advantages of droplet PCR for multiplexing combined with amplicon-based NGS. By comparing d-multiSeq with a standard multiplex amplicon-based NGS, it was shown that partitioning prevents the amplification competition seen when multiplexing and leads to a homogeneous representation of each target in the total read count for up to a 40-target multiplex without the need for prior adjustment. Variant allele frequency was reliably evaluated with a sensitivity of 97.6% for variant allele frequency up to 1%. The applicability of d-multiSeq was also tested on cell-free DNA with the successful amplification of an eight-target multiplex panel. Preliminary application of the technique to assess the clonal evolution in a childhood leukemia harboring high interpatient variability in its somatic variants is shown. d-multiSeq represents a turnkey solution for analyzing large sets of patient-specific variants on low DNA amounts and cell-free DNA.

SAMHD1 single nucleotide polymorphisms impact outcome in children with newly diagnosed acute myeloid leukemia.

Cytarabine arabinoside (Ara-C) has been the cornerstone of acute myeloid leukemia (AML) chemotherapy for decades. After cellular uptake, it is phosphorylated into its active triphosphate form (Ara-CTP), which primarily exerts its cytotoxic effects by inhibiting DNA synthesis in proliferating cells. Interpatient variation in the enzymes involved in the Ara-C metabolic pathway has been shown to affect intracellular abundance of Ara-CTP and, thus, its therapeutic benefit. Recently, SAMHD1 (SAM and HD domain-containing deoxynucleoside triphosphate triphosphohydrolase 1) has emerged to play a role in Ara-CTP inactivation, development of drug resistance, and, consequently, clinical response in AML. Despite this, the impact of genetic variations in SAMHD1 on outcome in AML has not been investigated in depth. In this study, we evaluated 25 single nucleotide polymorphisms (SNPs) within the SAMHD1 gene for association with clinical outcome in 400 pediatric patients with newly diagnosed AML from 2 clinical trials, AML02 and AML08. Three SNPs, rs1291128, rs1291141, and rs7265241 located in the 3' region of SAMHD1 were significantly associated with at least 1 clinical outcome: minimal residual disease after induction I, event-free survival (EFS), or overall survival (OS) in the 2 cohorts. In an independent cohort of patients from the COG-AAML1031 trial (n= 854), rs7265241 A>G remained significantly associated with EFS and OS. In multivariable analysis, all the SNPs remained independent predictors of clinical outcome. These results highlight the relevance of the SAMHD1 pharmacogenomics in context of response to Ara-C in AML and warrants the need for further validation in expanded patient cohorts.

ID: 215134 Interpatient Variability in Neural Recruitment During Pudendal Nerve Stimulation - A Patient-Specific Computational Modeling Study

Pudendal nerve (PN) stimulation is an emerging neuromodulation technique for the treatment of refractory bladder dysfunction and pelvic pain, conditions affecting the quality-of-life and productivity of millions of individuals around the world. The PN is a mixed nerve originating from the S2-S4 sacral nerve roots and innervating the genital, perineal, and rectal regions. Although it has been studied extensively in preclinical settings, limited studies of PN stimulation have been performed in human subjects, and interpatient variability in outcomes are not well understood. Therefore, we created patient-specific computational models to study neural recruitment in human subjects undergoing PN stimulation as part of their clinical care.

Unraveling Dexamethasone-Induced Neurobehavioral and Sleep Problems in Children With ALL: Which Determinants Are Important?

Dexamethasone, the preferred corticosteroid in most treatment protocols for pediatric acute lymphoblastic leukemia (ALL), can induce undesirable side effects. Neurobehavioral and sleep problems are frequently reported, but the interpatient variability is high. We therefore aimed to identify determinants for parent-reported dexamethasone-induced neurobehavioral and sleep problems in pediatric ALL. Our prospective study included patients with medium-risk ALL and their parents during maintenance treatment. Patients were assessed before and after one 5-day dexamethasone course. Primary end points were parent-reported dexamethasone-induced neurobehavioral and sleep problems, measured with the Strengths and Difficulties Questionnaire and Sleep Disturbance Scale for Children, respectively. Analyzed determinants included patient and parent demographics, disease and treatment characteristics, parenting stress (Parenting Stress Index and Distress Thermometer for Parents), dexamethasone pharmacokinetics, and genetic variation (candidate single-nucleotide polymorphisms rs41423247 and rs4918). Statistically significant determinants identified in univariable logistic regression analyses were incorporated in a multivariable model. We included 105 patients: median age was 5.4 years (range, 3.0-18.8) and 61% were boys. Clinically relevant dexamethasone-induced neurobehavioral and sleep problems were reported by parents in 70 (67%) and 61 (59%) patients, respectively. In our multivariable regression models, we identified parenting stress as a significant determinant for parent-reported neurobehavioral (odds ratio [OR], 1.16; 95% CI, 1.07 to 1.26) and sleep problems (OR, 1.06; 95% CI, 1.02 to 1.10). Furthermore, parents who experienced more stress before start of a dexamethasone course reported more sleep problems in their child (OR, 1.16; 95% CI, 1.02 to 1.32). We identified parenting stress, and not dexamethasone pharmacokinetics, genetic variation, patient/parent demographics, or disease/treatment characteristics, as a significant determinant for parent-reported dexamethasone-induced neurobehavioral and sleep problems. Parenting stress may be a modifiable target to reduce these problems.

Polygenic risk of anthracycline-related cardiomyopathy in childhood cancer survivors: Report from children’s oncology group and childhood cancer survivor study.

12090 Background: Considerable inter-patient variability in anthracycline-related cardiomyopathy (aCM) risk exists among childhood cancer survivors (CCS). A polygenic risk score (PRS) that accounts for combined effects of multiple genetic variants is established in other clinical situations, but remains understudied in anthracycline-exposed CCS. Methods: For discovery, a case-control set of 278 anthracycline-exposed non-Hispanic White (NHW) CCS (129 aCM cases; 149 controls) matched on primary cancer diagnosis, year of diagnosis and duration of follow-up was included from a Children’s Oncology Group study (COG-ALTE03N1). Genomic DNA underwent whole exome sequencing (100X depth). We searched Medline and Embase databases between 2005 and 2022 to curate evidence for published single nucleotide polymorphisms (SNPs) associated with CM. We identified 1,156 SNPs on 343 genes with minor allele frequency [MAF] ≥0.05 in white populations. We constructed a weighted PRS using sequenced SNPs that were linkage disequilibrium pruned, yielding a final list of 279 independent SNPs. Conditional logistic regression models adjusted for anthracycline dose, age at diagnosis, sex, chest radiation and cardiovascular risk factors (CVRFs; diabetes, hypertension, dyslipidemia) were used to estimate PRS-aCM associations. An independent population of 475 anthracycline-exposed NHW CCS from the Childhood Cancer Survivor Study (CCSS: 96 cases; 379 matched controls) was used to replicate the PRS-aCM association. Area under the receiver operating characteristic curve (AUC) was used to evaluate the performance of a model including the PRS. Results: Median age at primary cancer diagnosis was 7y for cases and controls in the Discovery and 11y in the Replication set. Mean anthracycline dose was higher for cases (Discovery: 312 v 186 mg/m2; Replication: 333 v 289 mg/m2). Cases were more likely to have received chest radiation (Discovery: 35.7% v 24.8%; Replication: 34.3% v 23.2%); and were more likely to have a CVRF (Discovery: 37.2% v 8.7%; Replication: 55.2% v 31.9%). PRScontinuous was significantly associated with aCM (aOR = 2.09, 95%CI: 1.1-4.0, p = 0.024) in the Discovery set. Compared to a model with clinical variables only, a model including the PRS had significant predictive performance: AUCclin= 0.72, 95% CI: 0.65-0.79. v AUCclin+PRS= 0.91, 95% CI: 0.87-0.95, p < 0.001. In the Replication set, the top PRS quartile (top 25%) was significantly associated with aCM (aOR = 2.14, 95%CI: 1.05-4.37, p = 0.036; reference: lowest PRS quartile). Conclusions: The significant association between this comprehensively curated PRS and aCM in CCS could serve as an important tool to identify survivors at increased risk for CM and inform targeted interventions.

Proposition of a drug score to predict the clinical usefulness of therapeutic dose monitoring of oral molecularly targeted therapies.

3091 Background: Therapeutic drug monitoring (TDM) consists in measuring and interpreting drug concentrations in biological fluids to personalize drug dosage. This method is widely used for drugs with a narrow therapeutic index ( e.g., immunosuppressants or neuroleptics agents). In onco-hematology, current recommendations of TDM for oral molecularly targeted therapies (oMTT) differ among molecules, making it difficult to identify good TDM candidates. This study aims to propose a quantitative approach with a score to predict the clinical usefulness of TDM of oMTT. Methods: We selected the four key parameters needed for an oMTT to be a good candidate for TDM (e.g. interpatient pharmacokinetic variability, feasible dose-adaptation strategy, exposure-efficacy relationship, exposure-safety relationship). We collected each drug’s pharmacokinetic (PK) and pharmacodynamics variables from drug labels, Center for Drug Evaluation and Research reports and early trials data. The score was defined from oMTT’s exposition variability (variability score: coefficient of variation of drug exposition, the impact of food and proton pump inhibitors), technical complexity (PK linearity, active metabolite, half-life), efficacy (Exposure-response relationship (ERR)) and safety (maximum tolerated dose, Exposure-safety relationship (ESR)). The global score ranged from 0 to 100. To assess the relevance of the score, we evaluated molecules from other therapeutic classes with known strong recommendations of TDM (clozapine, everolimus, voriconazole). Results: In September 2021, we collected data from sixty-seven oMTTs. Scores were normally distributed (mean 48.3, standard deviation 15.6) and varies from 15 for acalabrutinib to 80 for sunitinib. Scores of drugs with strong recommendation of TDM were 68, 68 and 64 for clozapine, everolimus as an immunosuppressant, and voriconazole, respectively. We hypothesized that a score above 60 might be associated with relevant indications of TDM. Fifteen molecules had a score above 60 (sunitinib (80), cabozantinib (76.5), nilotinib (76), abemaciclib (76), axitinib (75), sorafenib (69.5) gefitinib (69.5), trametinib (67.5), talazoparib (67), crizotinib (66), pazopanib (65), sonidegib (63.5), neratinib (62.5), panobinostat (62) and imatinib (60.5)). Conclusions: We defined a score to identify good candidates for TDM in onco-hematology. Usefulness of TDM in oncology should be confirmed prospectively prioritizing these molecules.

ID: 203787 Patient-Specific Computational Models to Characterize Physiological Effects of Spinal Cord Stimulation for Chronic Pain Management

Spinal cord stimulation (SCS) is an electric stimulation therapy for managing intractable chronic pain. However, because we do not fully understand the mechanisms of action of SCS, it is difficult to optimize stimulation efficacy and account for interpatient variability in therapeutic parameters. Therefore, the goal of this work was to use a patient-specific computational modeling approach to investigate the variability of neural activation across patients undergoing SCS as part of their clinical care. Understanding differences in neural activation may provide insight into outcome variability as well as the mechanisms of action of SCS.

ID: 215136 Inter-Patient Variability in the Evoked Compound Action Potentials Generated During Spinal Cord Stimulation

A paresthesia-centric closed-loop spinal cord stimulation (SCS) system described recently uses evoked compound action potentials (ECAPs) as a control signal to compensate for spinal cord movement [1]. While ECAP-based SCS has demonstrated clinical efficacy, significant knowledge gaps remain about how the main control variable (i.e., ECAP amplitude) and other metrics (e.g., ECAP threshold (ET), ECAP growth rate) vary across subjects, postures, and pulse widths. These knowledge gaps may complicate the appropriate application of ECAP-controlled, closed-loop SCS. Therefore, in this study, we utilized a combined experimental and computational modeling approach to answer these questions.

The effect of ctDNA tumor fraction (TF) on overall survival and concordance between tissue genomics and ctDNA in Lung-MAP.

9035 Background: Discordance in genomic profiling between tumor tissue and ctDNA can occur due to inter-patient variability in shed tumor DNA, and intra-patient variability in sources of cell-free DNA (tumor heterogeneity, metastatic variants, CHIP). TF is an aneuploidy-based estimation of tumor-specific DNA in circulation. We evaluated the impact of TF levels on overall survival (OS), mutation concordance and tumor mutation burden in tissue (tTMB) and ctDNA (bTMB) in the LUNGMAP screening study. Methods: Eligible advanced NSCLC pts had blood drawn ≤30 days of fresh tissue biopsy with no intervening therapies. Genomic profiling was done by FoundationOne CDx and FoundationOne Liquid CDx. ctDNA TF was quantified via aneuploidy using deviations in genome-wide SNP coverage or somatic allele frequencies if under aneuploidy LoD. High TF was defined as ≥10%. Concordance among driver genes, cancer genes of interest (CGoI: T P53, PIK3CA, STK11, KEAP1, RB1, PTEN, ATM, BRCA1/2), and variant subtype were assessed by the percentage positive agreement (PPA) and positive predictive value (PPV) with 95% confidence intervals (CI). OS by TF used a Cox model and log-rank test. PPA and TF among CGoIs was compared with a Wilcoxon test. Correlation between tTMB and bTMB used Lin’s coefficient (LC). Results: 167 pts met inclusion criteria; 161 had TF data with 51 (32%) ≥10% (high TF). High TF was associated with worse OS (HR: 2.06 [1.43-2.95], p<0.001). The PPA and PPV ranged from 50%-100% and 60%-100%, respectively for driver genes. The PPA was numerically larger for high versus low TF for most drivers (p=0.18) and significantly larger for all mutations and SNVs combined (Table). For CGoI, the distribution of PPA differed between high and low TF (p=0.03). The median PPA for CGoI (25th%ile,75th%ile) was 56% (50,87) for low TF and 100% (100,100) for high TF. PPV for CGoI did not differ by TF (p=0.20). High TF was associated with higher levels of TMB and bTMB (p<0.01 for both). TMB LC (CI) for low and high TF were 0.46 (0.27,0.61) and 0.69 (0.53,0.81). Conclusions: High TF was associated with worse OS, better PPA among CGoI, and better LC for t/bTMB. TF may improve the clinical utility of mutations detected by liquid biopsies and should be reported and considered in interpreting these results. [Table: see text]

Antifungal Stewardship Programs in Children: Challenges and Opportunities.

Antifungal Stewardship Programs in Children: Challenges and Opportunities.

Modulation Effects of the CEP128 Gene on Radiotherapy-Related Brain Injury: A Longitudinal Structural Study Using Multi-Parametric Brain MR Images.

The promoter variant rs17111237 in the CEP128 closely relates to radiotherapy (RT)-related brain necrosis in nasopharyngeal carcinoma (NPC) patients. To explore RT-related dynamic alterations in brain morphology and their potential genetic mechanism, and to explore the modulatory effects of CEP128 genetic variants on RT-related brain morphological alterations in NPC patients. Prospective, longitudinal. One hundred one patients with histopathologic ally-proven NPC (age 41.64 ± 9.63, 46 male), analyzed at baseline (pre-RT), 3-months post-RT and 6 months post-RT, and 19 sex-, age- and education-matched healthy controls. 3D gradient echo brain volume (3D-BRAVO) and diffusion-weighted single-shot spin-echo echo-planar sequences at 3.0 T. rs17111237 in CEP128 was detected by Sanger sequencing. Structural and diffusion images were processed with FreeSurfer and FSL. Morphometric similarity network (MSN) was constructed with nine cortical indices derived from structural and diffusion images. One-way ANOVA, chi-square test. Pearson's correlation analysis was conducted to measure the relationship between CEP128 gene-expression level in human brain and MSN alterations. Repeated analysis of variance performed to assess group differences in MSN and the modulatory effects of the CEP128 gene within patients. Significance level: P < 0.05, false-discovery rate correction. RT-related significant widespread MSN alterations were observed in the cortices of NPC patients. Notably, regional MSN alterations had a weak but significant negative correlation with the cortical pattern of CEP128 gene expression (r = -0.152). Furthermore, rs17111237 in the CEP128 had significant modulatory effects on the observed MSN alterations in NPC patients, with the modulatory effects being most obvious at 3 months post-RT. MSN has potential to serve as a sensitive biomarker to detect RT-related brain injury. Inter-brain regional and inter-patient variability of RT-related brain injuries may be attributed to the cortical expression of the CEP128 gene and the modulatory effects of the promoter variant rs17111237 in CEP128. 2 TECHNICAL EFFICACY: Stage 2.

A Population Pharmacokinetic Model of Pentobarbital for Children with Status Epilepticus and Severe Traumatic Brain Injury.

Pentobarbital pharmacokinetics (PK) remain elusive and the therapeutic windows narrow. Administration is frequent in critically ill children with refractory status epilepticus (SE) and severe traumatic brain injury (sTBI). To investigate pentobarbital PK in SE and sTBI patients admitted to the paediatric intensive care unit (PICU) with population-based PK (PopPK) modelling and dosing simulations. Develop a PopPK model with non-linear mixed-effects modelling (NONMEM®) with retrospective data (n = 36; median age 1.3 years; median weight 10 kg; 178 blood samples) treated with continuous intravenous pentobarbital. An independent dataset was used for external validation (n = 9). Dosing simulations with the validated model evaluated dosing regimens. A one-compartment PK model with allometrically scaled weight on clearance (CL; 0.75) and volume of distribution (Vd; 1) captured data well. Typical CL and Vd values were 3.59 L/70 kg/h and 142 L/70 kg, respectively. Elevated creatinine and C-reactive protein (CRP) levels significantly correlated to decreased CL, explaining 84% of inter-patient variability, and were incorporated in the final model. External validation using stratified visual predictive checks showed good results. Simulations demonstrated patients with elevated serum creatinine and CRP failed to achieve steady state yet progressed to toxic levels with current dosing regimens. The one-compartment PK model of intravenous pentobarbital described data well whereby serum creatinine and CRP significantly correlated with pentobarbital CL. Dosing simulations formulated adjusted dosing advice in patients with elevated creatinine and/or CRP. Prospective PK studies with pharmacodynamic endpoints, are imperative to optimise pentobarbital dosing in terms of safety and clinical efficacy in critically ill children.

Measuring Tumour Imatinib Concentrations in Gastrointestinal Stromal Tumours: Relevant or Redundant?

Imatinib plasma trough concentrations are associated with efficacy for patients treated for advanced or metastatic KIT-positive gastrointestinal stromal tumours (GISTs). This relationship has not been studied for patients treated in the neoadjuvant setting, let alone its correlation with tumour drug concentrations. In this exploratory study we aimed to determine the correlation between plasma and tumour imatinib concentrations in the neoadjuvant setting, investigate tumour imatinib distribution patterns within GISTs, and analyse its correlation with pathological response. Imatinib concentrations were measured in both plasma and in three regions of the resected primary tumour: the core, middle part, and periphery. Twenty-four tumour samples derived from the primary tumours of eight patients were included in the analyses. Imatinib tumour concentrations were higher compared to plasma concentrations. No correlation was observed between plasma and tumour concentrations. Interpatient variability in tumour concentrations was high compared to interindividual variability in plasma concentrations. Although imatinib accumulates in tumour tissue, no distribution pattern of imatinib in tumour tissue could be identified. There was no correlation between imatinib concentrations in tumour tissue and pathological treatment response.

The upper and lower respiratory tract microbiome in severe aspiration pneumonia

Uncertainty persists whether anaerobic bacteria represent important pathogens in aspiration pneumonia. In a nested case-control study of mechanically ventilated patients classified as macro-aspiration pneumonia (MAsP, n= 56), non-macro-aspiration pneumonia (NonMAsP, n= 91), and uninfected controls (n= 11), we profiled upper (URT) and lower respiratory tract (LRT) microbiota with bacterial 16S rRNA gene sequencing, measured plasma host-response biomarkers, analyzed bacterial communities by diversity and oxygen requirements, and performed unsupervised clustering with Dirichlet Multinomial Models (DMM). MAsP and NonMAsP patients had indistinguishable microbiota profiles by alpha diversity and oxygen requirements with similar host-response profiles and 60-day survival. Unsupervised DMM clusters revealed distinct bacterial clusters in the URT and LRT, with low-diversity clusters enriched for facultative anaerobes and typical pathogens, associated with higher plasma levels of SPD and sCD14 and worse 60-day survival. The predictive inter-patient variability in these bacterial profiles highlights the importance of microbiome study in patient sub-phenotyping and precision medicine approaches for severe pneumonia.

LAG-3 transcriptomic expression patterns across malignancies: Implications for precision immunotherapeutics.

Lymphocyte activation gene 3 (LAG-3) or CD223 is a transmembrane protein that serves as an immune checkpoint which attenuates T-cell activation. Many clinical trials of LAG-3 inhibitors have had modest effects, but recent data indicate that the LAG-3 antibody relatlimab, together with nivolumab (anti-PD-1), provided greater benefit than nivolumab alone in patients with melanoma. In this study, the RNA expression levels of 397 genes were assessed in 514 diverse cancers at a clinical-grade laboratory (OmniSeq: https://www.omniseq.com/). Transcript abundance was normalized to internal housekeeping gene profiles and ranked (0-100 percentile) using a reference population (735 tumors; 35 histologies). A total of 116 of 514 tumors (22.6%) had high LAG-3 transcript expression (≥75 percentile rank). Cancers with the greatest proportion of high LAG-3 transcripts were neuroendocrine (47% of patients) and uterine (42%); colorectal had among the lowest proportion of high LAG-3 expression (15% of patients) (all p < 0.05 multivariate); 50% of melanomas were high LAG-3 expressors. There was significant independent association between high LAG-3 expression and high expression of other checkpoints, including programmed death-ligand 1 (PD-L1), PD-1, and CTLA-4, as well as high tumor mutational burden (TMB) ≥10 mutations/megabase, a marker for immunotherapy response (all p < 0.05 multivariate). However, within all tumor types, there was inter-patient variability in LAG-3 expression level. Prospective studies are therefore needed to determine if high levels of the LAG-3 checkpoint are responsible for resistance to anti-PD-1/PD-L1 or anti-CTLA-4 antibodies. Furthermore, a precision/personalized immunotherapy approach may require interrogating individual tumor immunograms to match patients to the right combination of immunotherapeutic agents for their malignancy.