Germline genetic regulation of the colorectal tumor immune microenvironment

OBJECTIVE

To evaluate the contribution of germline genetics to regulating the briskness and diversity of T cell responses in CRC, we conducted a genome-wide association study to examine the associations between germline genetic variation and quantitative measures of T cell landscapes in 2,876 colorectal tumors from participants in the Molecular Epidemiology of Colorectal Cancer Study (MECC).

METHODS

Germline DNA samples were genotyped and imputed using genome-wide arrays. Tumor DNA samples were extracted from paraffin blocks, and T cell receptor clonality and abundance were quantified by immunoSEQ (Adaptive Biotechnologies, Seattle, WA). Tumor infiltrating lymphocytes per high powered field (TILs/hpf) were scored by a gastrointestinal pathologist. Regression models were used to evaluate the associations between each variant and the three T-cell features, adjusting for sex, age, genotyping platform, and global ancestry. Three independent datasets were used for replication.

RESULTS

We identified a SNP (rs4918567) near RBM20 associated with clonality at a genome-wide significant threshold of 5 × 10- 8, with a consistent direction of association in both discovery and replication datasets. Expression quantitative trait (eQTL) analyses and in silico functional annotation for these loci provided insights into potential functional roles, including a statistically significant eQTL between the T allele at rs4918567 and higher expression of ADRA2A (P = 0.012) in healthy colon mucosa.

CONCLUSIONS

Our study suggests that germline genetic variation is associated with the quantity and diversity of adaptive immune responses in CRC. Further studies are warranted to replicate these findings in additional samples and to investigate functional genomic mechanisms.

Perioperative management of a double valve replacement and coronary artery bypass graft in a patient with carcinoid syndrome; a case report and literature review

INTRODUCTION

Carcinoid tumors are rare neuroendocrine tumors; about 5% of patients develop the carcinoid syndrome. We present the case of a patient with carcinoid syndrome undergoing cardiac surgery.

CASE REPORT

A 74-year-old patient with carcinoid heart disease and hepatic metastases underwent double valve replacement and CABG. The patient was on octreotide therapy and antihypertensive medication. An octreotide infusion was commenced perioperatively. Pharmaceutical agents that could potentially precipitate histamine release or exacerbate catecholamine secretion and carcinoid crises were avoided. Postoperatively, recovery was complicated by atrial fibrillation, chest infection, pleural effusions, acute kidney injury and delirium.

DISCUSSION

Hepatic metastases cause systemic hormones' secretion, which cause a carcinoid crisis. Perioperative administration of octreotide is used, while vigilance is required to differentiate between hemodynamic effects related to the operation or disease specific factors.

CONCLUSION

No carcinoid crisis was evident perioperatively. High vigilance with appropriate monitoring, aggressive management combined with meticulous choice of pharmaceutical agents led to this outcome.

Heterozygote advantage at HLA class I and II loci and reduced risk of colorectal cancer

Objective

Reduced diversity at Human Leukocyte Antigen (HLA) loci may adversely affect the host's ability to recognize tumor neoantigens and subsequently increase disease burden. We hypothesized that increased heterozygosity at HLA loci is associated with a reduced risk of developing colorectal cancer (CRC).

Methods

We imputed HLA class I and II four-digit alleles using genotype data from a population-based study of 5,406 cases and 4,635 controls from the Molecular Epidemiology of Colorectal Cancer Study (MECC). Heterozygosity at each HLA locus and the number of heterozygous genotypes at HLA class -I (A, B, and C) and HLA class -II loci (DQB1, DRB1, and DPB1) were quantified. Logistic regression analysis was used to estimate the risk of CRC associated with HLA heterozygosity. Individuals with homozygous genotypes for all loci served as the reference category, and the analyses were adjusted for sex, age, genotyping platform, and ancestry. Further, we investigated associations between HLA diversity and tumor-associated T cell repertoire features, as measured by tumor infiltrating lymphocytes (TILs; N=2,839) and immunosequencing (N=2,357).

Results

Individuals with all heterozygous genotypes at all three class I genes had a reduced odds of CRC (OR: 0.74; 95% CI: 0.56-0.97, p= 0.031). A similar association was observed for class II loci, with an OR of 0.75 (95% CI: 0.60-0.95, p= 0.016). For class-I and class-II combined, individuals with all heterozygous genotypes had significantly lower odds of developing CRC (OR: 0.66, 95% CI: 0.49-0.87, p= 0.004) than those with 0 or one heterozygous genotype. HLA class I and/or II diversity was associated with higher T cell receptor (TCR) abundance and lower TCR clonality, but results were not statistically significant.

Conclusion

Our findings support a heterozygote advantage for the HLA class-I and -II loci, indicating an important role for HLA genetic variability in the etiology of CRC.

Differences in tumor-associated T cell receptor repertoires between young-onset and average-onset colorectal cancer

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Background: The incidence of colorectal cancer (CRC) among individuals younger than age 50 (young-onset CRC; YOCRC) has increased, yet the etiology and molecular mechanisms underlying this alarming rise remain unclear. Some studies suggest that YOCRCs have more aggressive biology. Here, we compare tumor-associated T cell repertoires between patients with YOCRC and average-onset CRC (AOCRC). A robust, focused T cell response is a positive prognostic indicator; therefore, we hypothesized that YOCRCs demonstrate lower T cell abundance and greater T cell diversity than AOCRCs. Methods: The discovery cohort included 242 patients with histologically confirmed Stage I-IV CRC who underwent surgical resection at Cleveland Clinic from 2000 to 2020 and consented to a biorepository. YOCRC was defined as < 50 years at diagnosis (N = 126), and AOCRC as > 60 years (N = 116). DNA was extracted from frozen tumors, and T Cell Receptor (TCR) abundance and clonality were measured using immunoSEQ (Adaptive Biotechnologies). Following quality control, logistic regression models were used to evaluate the associations between TCR repertoire features and age of onset, adjusting for sex, race, tumor location, and stage. Findings were replicated in 152 YOCRC and 1,984 AOCRC cases from the Molecular Epidemiology of Colorectal Cancer Study with adjustment for sex, Jewish ethnicity, tumor location, and stage. Results: YOCRC patients were more likely to have left-sided tumors and be diagnosed at advanced stages in both cohorts. In the discovery cohort, YOCRC tumors had significantly lower TCR clonality (higher T cell diversity) compared to AOCRC tumors in a multivariable model adjusting for sex, race, tumor location and stage (OR: 0.38, 95% Confidence Interval (CI): 0.25-0.56, p < 0.0001). This association was also observed in the replication cohort (OR: 0.74, 95% CI: 0.62-0.89, p = 0.0013). In the replication cohort, further adjustment for microsatellite instability status did not substantially change the association (OR: 0.73, 95% CI: 0.61-0.88 p = 0.0012). When restricting to microsatellite stable tumors, clonality remained statistically significant in both the discovery and replication cohorts. No significant difference in TCR abundance was observed between YOCRC and AOCRC in either cohort. Conclusions: Higher T cell repertoire diversity, indicating a less focused intratumoral T cell response, is more frequently observed in YOCRC. Further studies are warranted to investigate the role of T cell diversity in the etiology and outcomes of YOCRC.

Chronic pain treatment with pregabalin in end stage respiratory failure patients awaiting lung transplantation on ambulatory veno-venous extra corporeal membrane oxygenator support; a series of nine cases

Background

End-stage respiratory failure is non-treatable with mechanical ventilation and can be treated with veno-venous extracorporeal membrane oxygenators (VV-ECMO). It can also be used as a bridge to lung transplantation or recovery of lung function. This patient group can suffer from chronic pain, which is further exacerbated by painful procedures required as part of treatment. Pregabalin is licensed for chronic neuropathic pain and generalized anxiety disorder. Thus far, it has not been tried in routine analgesia protocols for pain relief of patients on VV-ECMO.

Case Series

We included nine patients aged 17-54 years on VV-ECMO awaiting lung transplantation. Exclusion criteria were acute kidney injury and chronic kidney disease. All patients had morphine patient-control analgesia. In addition, pregabalin 50 mg twice daily was initiated in all patients with dose escalation as required. Pain scores and quality of sleep were evaluated daily. All patients experienced significant pain relief, demonstrated by reduced pain scores after treatment commencement. The mean visual analogue scale score was reduced significantly from 6 ± 2 to 3 ± 1. A significant increase in good-quality sleep duration was recorded from 5 ± 1.7 hours per day before to 8 ± 2.1 hours per day after pregabalin treatment. All patients except for two reported reduced anxiety levels of at least 2 ± 1 scale improvement (p <0.05).

Conclusions

Pregabalin is an efficient analgesic with accompanying anxiolytic effects in this group of patients with unique characteristics such as high analgesia requirements and exacerbated psychological and emotional stress. HIPPOKRATIA 2023, 27 (1):22-24.

Abstract 5874: Heterozygote advantage at HLA class I and II loci and colorectal cancer risk

Diversity in Human Leukocyte Antigen (HLA) genes has been associated with risk of several diseases, including Non-Hodgkin’s lymphoma and ulcerative colitis. Reduced diversity at HLA loci may adversely affect the host’s ability to recognize foreign antigens and tumor neoantigens, and subsequently, increase disease burden. To better understand the role of inherited HLA diversity in colorectal cancer (CRC) risk, we utilized data from a population-based study of 10,347 participants (5,574 CRC cases and 4,773 healthy controls) from the Molecular Epidemiology of Colorectal Cancer Study (MECC). Germline DNA samples were genotyped using genome-wide arrays, and HLA Class I and II four-digit resolution alleles were imputed using SNP2HLA and a reference panel of 5,225 individuals from the Type 1 Diabetes Genetics Consortium. Heterozygosity and homozygosity at each HLA locus and the number of homozygous genotypes at class I loci (A, B, C) and class II loci (DQB1, DRB1, DPB1) were quantified. To examine the joint effect of Class I and Class II loci, we combined the total number of homozygotes for all loci and categorized into 3 groups: heterozygotes at all loci, 1 to 4 homozygotes, or 5 or more homozygotes. Logistic regression was used to estimate the risk of CRC associated with HLA locus homozygosity. Individuals with heterozygous genotypes for all loci served as the reference category, and analyses were adjusted for sex, age, genotyping platform, and global ancestry. Individuals with homozygous genotypes at all 3 Class I genes had an increased risk of CRC when compared to those with heterozygous genotypes at all Class I loci (OR: 1.34; 95% CI: 1.02-1.76, P = 0.033; Ptrend = 0.039). A similar association was observed for Class II loci, with an OR of 1.32 (95% CI: 1.05-1.65, P = 0.015; Ptrend = 0.157). For HLA Class I and II combined, individuals with five or more homozygous genotypes at HLA class I or II loci were at higher risk for developing CRC (OR: 1.84, 95% CI: 1.24-2.73, P = 0.0023; Ptrend = 0.015), when compared to those with all heterozygous genotypes. Our findings support a heterozygote advantage at HLA class I and II loci as a protective factor for CRC. This indicates an important role for HLA genetic variability in the etiology of CRC potentially operating through a mechanism of decreased diversity of tumor neoantigens that can be displayed to the adaptive immune system.

Citation Format: Ya-Yu Tsai, Chenxu Qu, Joseph D. Bonner, Rebeca Sanz-Pamplona, Sidney Lindsey, Marilena Melas, Kevin J. McDonnell, Gregory E. Idos, Christopher P. Walker, Kevin K. Tsang, Diane M. Da Silva, Ferran Moratalla, Asaf Maoz, Hedy S. Rennert, W. Martin Kast, Joel K. Greenson, Victor Moreno, Gad Rennert, Stephen B. Gruber, Stephanie L. Schmit. Heterozygote advantage at HLA class I and II loci and colorectal cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5874.

Abstract 2737: Clinical and epidemiologic predictors of clonal immune responses in colorectal cancer

The quantity and quality of immune responses in colorectal cancers (CRC) are widely variable and have important clinical, therapeutic, and prognostic implications. We studied clinical and epidemiologic factors that might influence T-cell quantity and clonality within colorectal adenocarcinomas to better understand the drivers of diverse immune responses. Incident cases of CRC from the Molecular Epidemiology of Colorectal Cancer Study (MECC) were interviewed, and 6,006 cases had complete epidemiologic data. Archived tumor blocks were retrieved from 3,865 (64.4%) cases, and all were reviewed by a single expert pathologist who quantified TILS/hpf. Sufficient tissue for macrodissection and measurement of TCR abundance and clonality using the immunoSEQ assay (Adaptive Biotechnologies) was available and completed for 2,750 cases. Logistic regression, negative binomial regression and linear regression models were used to evaluate potential associations between clinical and epidemiologic variables for: TILS/hpf, TCR abundance, and T-cell clonality. The stage distribution was representative of cancer incidence in the population, and the MSI-H phenotype was observed in 14.2% of cases. Clinical, pathologic, and epidemiologic variables including aspirin, alcohol, diet, hormone use, physical activity, smoking, and statins were assessed in relation to immune measures. Among other findings, &gt;5 years of statins (p&lt;0.001) and daily aspirin (p=0.037) were each strongly associated with T-cell clonality. Our study suggests that important parameters of the adaptive immune response may be mediated by modifiable factors. Mechanisms regulating immune responses in CRC may have implications for chemoprevention as well as immunotherapy.

Citation Format: Stephen B. Gruber, Joseph D. Bonner, Sidney S. Lindsey, Ya-Yu Tsai, Rebeca Sanz-Pamplona, M. Henar Alonso, Marilena Melas, Hedy S. Rennert, Kevin J. McDonnell, Gregory E. Idos, Christopher P. Walker, W. Martin Kast, Diane Da Silva, Harlan S. Robins, Joel K. Greenson, Victor Moreno, Stephanie L. Schmit, Gad Rennert. Clinical and epidemiologic predictors of clonal immune responses in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2737.

Abstract 824: Germline genetic regulation of the adaptive immune response in colorectal cancer

Adaptive immune responses in the tumor microenvironment of colorectal cancer (CRC) play an important role in prognosis. However, the contributions of germline genetic variations to the strength and diversity of T cell responses in CRC are unclear. We conducted a genome-wide association study to examine the relationships between germline genetic variants and measures of the T cell repertoire in colorectal tumors. Germline DNA samples from 5,581 CRC cases recruited into the Molecular Epidemiology of Colorectal Cancer Study (MECC) were genotyped in batches using four different platforms. Genotype data were imputed to the Haplotype Reference Consortium panel separately by genotyping platform. Tumor DNA samples were extracted from paraffin blocks, and tumor infiltrating lymphocytes per high powered field (TILs/hpf) were quantified by a single gastrointestinal pathologist. TCR abundance and clonality within individual CRCs were measured using the immunoSEQ assay (Adaptive Biotechnologies). Appropriate quality control steps and data transformations were applied to fit downstream statistical modeling assumptions. After standard quality control on both imputed genotypes and transformed immune metrics, 2,876 (TILs/hpf) and 2,395 (TCR abundance and clonality) cases with approximately 9 million imputed genetic variants were included in the discovery phase. Logistic or linear regression models were used to evaluate the associations between allelic dosage of each variant and each immune-related outcome, adjusting for sex, age at diagnosis, genotyping platform, and principal components for global ancestry. Three independent datasets were available to replicate our findings using similar quality control measures and regression models: Colonomics (N=96; TILs/hpf, TCR abundance, clonality), the CRC Genetics Study (N=162; TCR abundance, clonality), and the Harvard Cohorts (N=505; TILs/hpf; in progress). The discovery phase identified 5 independent genetic variants associated with TILs/hpf, 15 associated with TCR abundance, and 19 associated with clonality at p&lt;5X10E-06. Replication analyses as well as expression quantitative trait analyses and in silico functional annotation are underway for the loci of interest. Our study suggests that germline genetic variation is associated with the quantity and quality of adaptive immune responses in CRC.

Citation Format: Stephanie L. Schmit, Ya-Yu Tsai, Joseph Bonner, Rebeca Sanz-Pamplona, Amit D. Joshi, Sidney S. Lindsey, Marilena Melas, Kevin J. McDonnell, Gregory E. Idos, Christopher P. Walker, W. Martin Kast, Diane Da Silva, Tomotaka Ugai, Hedy S. Rennert, Harlan S. Robins, Joel K. Greenson, Shuji Ogino, Victor Moreno, Gad Rennert, Stephen B. Gruber. Germline genetic regulation of the adaptive immune response in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 824.

Abstract 835: T-cell abundance, clonality and disease specific survival in colorectal cancer

Immune responses to colorectal cancer (CRC) are important prognostic factors as measured by either tumor infiltrating lymphocytes per high powered field or the presence of Crohn's like lymphoid reaction. New technologies to quantify specific features of immune responses include immunoSeq (Adaptive Biotechnologies), which accurately quantifies T-cell receptor (TCR) abundance and T-cell receptor clonality. Here we measured the independent contributions of TCR abundance and TCR clonality to 5-year CRC-specific survival in the Molecular Epidemiology of Colorectal Cancer (MECC) study. The MECC study consented, interviewed, and followed 6,006 incident cases of CRC diagnosed between March 31, 1998 and July 1, 2017 (median follow-up time = 6.9 years). Archived paraffin blocks were retrieved, and 2,750 cases had sufficient tissue and adequate DNA extraction to perform the immunoSeq assay. Analyses were restricted to 1,625 samples with more than 100 T-cells to permit accurate quantification of TCR abundance and TCR clonality as measured by Simpson Clonality Index. TCR abundance was log2 transformed for analyses, and Simpson Clonality Index was log2-transformed and z-scale normalized separately by assay version. In unadjusted models, dichotomized log2 transformed TCR abundance (Hazard Ratio (HR) = 0.57, 95% confidence interval (CI) 0.47-0.71, p=9.77E-08) and dichotomized TCR clonality (HR = 0.77, 95% CI 0.63-0.94, p=0.01) were each statistically significantly associated with 5-year CRC-specific survival. In a model with adjustment for age, sex, microsatellite instability, stage and assay version, both dichotomized log2 transformed TCR abundance (HR = 0.61, 95% CI, 0.49-0.75, p=3.03E-06), and dichotomized TCR clonality (HR = 0.81, 95% CI, 0.66-0.99, p=0.048) were associated with improved 5-year disease-specific survival.

Conclusion: TCR abundance and TCR clonality are independent prognostic indicators in CRC.

Citation Format: Joseph Bonner, Sephanie L. Schmit, Sidney S. Lindsey, Ya-Yu Tsai, Rebeca Sanz-Pamplona, M. Henar Alonso, Marilena Melas, Hedy S. Rennert, Kevin J. McDonnell, Gregory Idos, Christopher P. Walker, W. Martin Kast, Diane Da Silva, Harlan S. Robins, Joel K. Greenson, Victor Moreno, Gad Rennert, Stephen B. Gruber. T-cell abundance, clonality and disease specific survival in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 835.

Carbohydrate Intake Prior to Oral Glucose Tolerance Testing

With the emergence of glycated hemoglobin as a diagnostic test for diabetes, oral glucose tolerance tests (OGTTs) have become rare in endocrinology practice. As they have moved out of favor, the importance of patient instructions on preparation prior to OGTT has faded from memory. Decades-old literature, well-known to endocrinologists a generation ago, emphasized the importance of carbohydrate intake prior to OGTT. In this expert endocrine consult, we discuss an OGTT performed in a research setting without adequate carbohydrate intake at the evening meal prior to the OGTT. The resultant elevated plasma glucose levels at 1-hour and 2-hours mimicked the loss of first-phase insulin release seen in early type 1 and type 2 diabetes. With clinical concern that the research participant had evolving type 1 or type 2 diabetes, the volunteer was subjected to additional testing and experienced anxiety. Repeat OGTT was normal after adequate carbohydrate intake (>150 grams/day and >50 grams the evening prior to overnight fast for the study). The physiology of this phenomenon is explored and is likely mediated through beta cell adaptation and alteration in peripheral glucose uptake in response to nutrient exposure. The learnings of decades ago have clearly faded, and this literature should be revisited to ensure that OGTT results are not compromised when ordered for clinical or research purposes.

Cone beam computed tomography for dose calculation quality assurance for magnetic resonance-only radiotherapy

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Clinical Magnetic Resonance (MR)-only radiotherapy requires a dose quality assurance method.

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Doses calculated on Cone Beam Computed Tomography (CBCT) were within 2% of MR-only doses calculated using synthetic CT.

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CBCT with asymmetric dose difference tolerances of [−2%,1%] appears clinically feasible for quality assurance of prostate MR-only radiotherapy.

Background and purpose

Magnetic Resonance (MR)-only prostate radiotherapy using synthetic Computed Tomography (sCT) algorithms with high dose accuracy has been clinically implemented. MR images can suffer from geometric distortions so Quality Assurance (QA) using an independent, geometrically accurate, image could be required. The first-fraction Cone Beam CT (CBCT) has demonstrated potential but has not been evaluated in a clinical MR-only pathway. This study evaluated the clinical use of CBCT for dose accuracy QA of MR-only radiotherapy.

Materials and methods

A total of 49 patients treated with MR-only prostate radiotherapy were divided into two cohorts. Cohort 1 (20 patients) received a back-up CT, whilst Cohort 2 (29 patients) did not. All patients were planned using the sCT and received daily CBCT imaging with MR-CBCT soft-tissue matching. Each CBCT was calibrated using a patient-specific stepwise Hounsfield Units-to-mass density curve. The treatment plan was recalculated on the first-fraction CBCT using the clinically applied soft-tissue match and the doses compared. For Cohort 1 the sCT was rigidly registered to the back-up CT, the plan recalculated and doses compared.

Results

Mean sCT-CBCT dose difference across both cohorts was -0.6±0.1% (standard error of the mean, range −2.3%,2.3%), with 47/49 patients within [-2%,1%]. The sCT-CBCT dose difference was systematically lower than the sCT-CT by -0.7±0.6% (±95% limits of agreement). The mean sCT-CBCT gamma pass rate (2%/2mm) was 96.1±0.4% (85.4%,99.7%).

Conclusions

CBCT-based dose accuracy QA for MR-only radiotherapy appears clinically feasible. There was a small systematic sCT-CBCT dose difference implying asymmetric tolerances of [-2%,1%] would be appropriate.

Experimental increase of blood glucose alters resting state EEG measures of excitation-inhibition balance

NEW FINDINGS

What is the central question of this study? Glucose is the dominant energy source for the brain. However, little is known about how glucose metabolism impacts the coordination of network activity in the brain in healthy adults. What is the main finding and its importance? We demonstrate that both α oscillations and the aperiodic signal components of the resting EEG are modulated by experimentally elevated blood glucose concentrations. Our findings suggest that glucose increases measures associated with excitation-inhibition (E:I) balance, but that the effect on α oscillations might plateau. Understanding the relationship between glucose consumption and E:I balance is crucial to developing our understanding of how metabolism shapes human brain activity.

ABSTRACT

Brain network oscillations can be divided broadly into periodic and aperiodic signal components, which are sensitive to state-dependent changes in network coordination and excitation-inhibition (E:I) balance. We sought to address whether the dominant energy source of the brain, glucose, is implicated in the regulation of network activity and excitability. We conducted an experimenter-blind, crossover study of the effect of blood glucose level (BGL) on the resting EEG frequency spectrum. Participants consumed a glucose drink (75 g glucose) or an equivalent volume of water on two separate visits. EEG data were sampled before and ≤3 h after the drink. We found that the experimentally induced changes in BGL exhibited an inverted U-shaped relationship, with changes in the individual α frequency peak, whereas the slope of the aperiodic signal component of the frequency spectrum showed a positive linear association suggestive of greater excitation. In contrast, peak α power, which is typically associated with top-down inhibitory processes, was negatively associated with changes in BGL. Collectively, these results suggest that high BGL alters brain network coordination in the form of α oscillations and measures associated with E:I balance.

Gene Expression in Patient-Derived Neural Progenitors Implicates WNT5A Signaling in the Etiology of Schizophrenia

BACKGROUND

Genome-wide association studies of schizophrenia have demonstrated that variations in noncoding regions are responsible for most of the common variation heritability of the disease. It is hypothesized that these risk variants alter gene expression. Therefore, studying alterations in gene expression in schizophrenia may provide a direct approach to understanding the etiology of the disease. In this study we use cultured neural progenitor cells derived from olfactory neuroepithelium (CNON cells) as a genetically unaltered cellular model to elucidate the neurodevelopmental aspects of schizophrenia.

METHODS

We performed a gene expression study using RNA sequencing of CNON cells from 111 control subjects and 144 individuals with schizophrenia. Differentially expressed genes were identified with DESeq2 software, using covariates to correct for sex, age, library batches, and 1 surrogate variable component.

RESULTS

A total of 80 genes were differentially expressed (false discovery rate < 10%), showing enrichment in cell migration, cell adhesion, developmental process, synapse assembly, cell proliferation, and related Gene Ontology categories. Cadherin and Wnt signaling pathways were positive in overrepresentation test, and, in addition, many genes were specifically involved in WNT5A signaling. The differentially expressed genes were modestly, but significantly, enriched in the genes overlapping single nucleotide polymorphisms with genome-wide significant association from the Psychiatric Genomics Consortium genome-wide association study of schizophrenia. We also found substantial overlap with genes associated with other psychiatric disorders or brain development, enrichment in the same Gene Ontology categories as genes with mutations de novo in schizophrenia, and studies of induced pluripotent stem cell-derived neural progenitor cells.

CONCLUSIONS

CNON cells are a good model of the neurodevelopmental aspects of schizophrenia and can be used to elucidate the etiology of the disorder.

Intact Auditory Cortical Cross-Frequency Coupling in Early and Chronic Schizophrenia

BACKGROUND

Previous work has identified a hierarchical organization of neural oscillations that supports performance of complex cognitive and perceptual tasks, and can be indexed with phase-amplitude coupling (PAC) between low- and high-frequency oscillations. Our aim was to employ enhanced source localization afforded by magnetoencephalography (MEG) to expand on earlier reports of intact auditory cortical PAC in schizophrenia and to investigate how PAC may evolve over the early and chronic phases of the illness.

METHODS

Individuals with early schizophrenia (n=12) (≤5 years of illness duration), chronic schizophrenia (n=16) (>5 years of illness duration) and healthy comparators (n = 17) performed the auditory steady state response (ASSR) to 40, 30, and 20 Hz stimuli during MEG recordings. We estimated amplitude and PAC on the MEG ASSR source localized to the auditory cortices.

RESULTS

Gamma amplitude during 40-Hz ASSR exhibited a significant group by hemisphere interaction, with both patient groups showing reduced right hemisphere amplitude and no overall lateralization in contrast to the right hemisphere lateralization demonstrated in controls. We found significant PAC in the right auditory cortex during the 40-Hz entrainment condition relative to baseline, however, PAC did not differ significantly between groups.

CONCLUSIONS

In the current study, we demonstrated an apparent sparing of ASSR-related PAC across phases of the illness, in contrast with impaired cortical gamma oscillation amplitudes. The distinction between our PAC and evoked ASSR findings supports the notion of separate but interacting circuits for the generation and maintenance of sensory gamma oscillations. The apparent sparing of PAC in both early and chronic schizophrenia patients could imply that the neuropathology of schizophrenia differentially affects these mechanisms across different stages of the disease. Future studies should investigate the distinction between PAC during passive tasks and more cognitively demanding task such as working memory so that we can begin to understand the influence of schizophrenia neuropathology on the larger framework for modulating neurocomputational capacity.

Abstract 2332: Tumor infiltrating lymphocytes, immunoSeq, and CMS classification in the molecular epidemiology of colorectal cancer study

Background: Tumor infiltrating lymphocytes (TILs) are prognostic and predictive biomarkers in colorectal cancer and are associated with improved prognosis and response to immunotherapy. While TILs are routinely assessed by pathologists, a standardized technique (immunoSEQ, Adaptive Biotechnologies) that leverages targeted next-generation sequencing can also be used to quantify and characterize the T-cell receptor (TCR) repertoire of individual colorectal cancers. In a large, population-based study of incident colorectal cancer, the host immune responses were measured by an expert pathologist and ImmunoSEQ to understand the relationships between TILs, TCRs/cell and specific subgroups of colorectal cancer. Methods: Incident cases of adenocarcinoma of the colon or rectum from the Molecular Epidemiology of Colorectal Cancer (MECC) study included 1,000 cancers that were uniformly evaluated for TILs and other histopathologic features by one pathologist. FFPE-derived DNA from microdissected tumor tissue was extracted and sequenced using ImmunoSEQ analysis for the same 1,000 individuals. A resulting quantitative metric from this assay includes TCRs/cell, a measure of rearranged T cell quantity relative to all nucleated cells in a tumor sample. Gene expression in snap-frozen tissue available from 342/1,000 MECC colorectal cancers was measured with Affymetrix Human Genome U133 Arrays (U133A and U133 Plus2.0) as previously described. CMS classification was performed using the R package 3.5.1, CMS classifier, randomForest 4.6-14. Multivariate analysis assessed CMS by age, gender, TILs/HPF, TCRs/cell, MSI status, BRAF and KRAS mutational status. Results: TILs/HPF and TCRs/cell were significantly correlated among all 1000 cases (r=0.5, p&lt;0.001). Among the 342 cases with available expression profiles, CMS1 constituted 12.0% of all CRC, with CMS2 (41.8%), CMS3 (8.5%), and CMS4 (13.7%) and unclassified (24%) representing the remaining distribution. There were statistically significant differences in the molecular and histopathologic features of colorectal cancers by CMS subgroups. MSI-H tumors were most frequently observed within CMS1 cancers (56.6% of CMS1 were MSI-H), with lower representation among CMS2 (1.5%), CMS3 (10%), CMS4 (3.5%), and unclassified CRC (9.5%) (p&lt;0.0001). In addition, BRAF positive tumors were more frequently observed within the CMS1 group (12.2%, p =0.0065) and KRAS positive tumors within the CMS3 group (31%, p&lt;0.0001). Consistent with prior reports, TILs/HPF were significantly higher in the CMS1 group (mean=7.7, p&lt;0.0001). Similar statistically significant trends were observed across classes for TCRs/cell (mean=0.16, p=0.04). Conclusions: Subtypes of CRC have distinct histopathologic and molecular features that can be distinguished by expression profiles and immunoSEQ.

Citation Format: Marilena Melas, Charalampos Lazaris, Stephanie L. Schmit, Asaf Maoz, Rebeca Sanz Pamplona, Chenxu Qu, Joel K. Greenson, Rork Kuick, Flavio Lejbkowicz, Hedy S. Rennert, Christopher P. Walker, Chase M. Bowen, Diane M. Da Silva, W. Martin Kast, Gregory E. Idos, Kevin J. McDonnell, Victor Moreno, Gad Rennert, Stephen B. Gruber. Tumor infiltrating lymphocytes, immunoSeq, and CMS classification in the molecular epidemiology of colorectal cancer study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2332.

Loss-of-function mutation in inositol monophosphatase 1 (IMPA1) results in abnormal synchrony in resting-state EEG

Background

Dysregulation of the inositol cycle is implicated in a wide variety of human diseases, including developmental defects and neurological diseases. A homozygous frameshift mutation in IMPA1, coding for the enzyme inositol monophosphatase 1 (IMPase), has recently been associated with severe intellectual disability (ID) in a geographically isolated consanguineous family in Northeastern Brazil (Figueredo et al., 2016). However, the neurophysiologic mechanisms that mediate the IMPA1 mutation and associated ID phenotype have not been characterized. To this end, resting EEG (eyes-open and eyes-closed) was collected from the Figueredo et al. pedigree. Quantitative EEG measures, including mean power, dominant frequency and dominant frequency variability, were investigated for allelic associations using multivariate family-based association test using generalized estimating equations.

Results

We found that the IMPA1 mutation was associated with relative decreases in frontal theta band power as well as altered alpha-band variability with no regional specificity during the eyes-open condition. For the eyes-closed condition, there was altered dominant theta frequency variability in the central and parietal regions.

Conclusions

These findings represent the first human in vivo phenotypic assessment of brain function disturbances associated with a loss-of-function IMPA1 mutation, and thus an important first step towards an understanding the pathophysiologic mechanisms of intellectual disability associated with the mutation that affects this critical metabolic pathway.

Serum anticholinergicity is associated with reduced prefrontal brain function in early course schizophrenia

Increased anticholinergic activity resulting from pharmacotherapies used to treat schizophrenia is associated with poorer cognition. However the neural mechanisms underlying this effect are unknown. In this study of 39 early course schizophrenia outpatients, we demonstrate that increased serum anticholinergic activity is associated with reduced activation across the prefrontal cortex, including the dorsolateral, anterior, and medial prefrontal cortices, during two tasks of cognitive control. Lower activation in the dorsolateral and anterior prefrontal cortices mediated the association between increased anticholinergicity and poorer neurocognitive function. Such findings provide preliminary insight into how anticholinergic medications may impact cognition through reduced prefrontal cortical function in schizophrenia.

Assessing characteristics of RNA amplification methods for single cell RNA sequencing

BACKGROUND

Recently, measurement of RNA at single cell resolution has yielded surprising insights. Methods for single-cell RNA sequencing (scRNA-seq) have received considerable attention, but the broad reliability of single cell methods and the factors governing their performance are still poorly known.

RESULTS

Here, we conducted a large-scale control experiment to assess the transfer function of three scRNA-seq methods and factors modulating the function. All three methods detected greater than 70% of the expected number of genes and had a 50% probability of detecting genes with abundance greater than 2 to 4 molecules. Despite the small number of molecules, sequencing depth significantly affected gene detection. While biases in detection and quantification were qualitatively similar across methods, the degree of bias differed, consistent with differences in molecular protocol. Measurement reliability increased with expression level for all methods and we conservatively estimate measurements to be quantitative at an expression level greater than ~5-10 molecules.

CONCLUSIONS

Based on these extensive control studies, we propose that RNA-seq of single cells has come of age, yielding quantitative biological information.

Development of sensory gamma oscillations and cross-frequency coupling from childhood to early adulthood

Given the importance of gamma oscillations in normal and disturbed cognition, there has been growing interest in their developmental trajectory. In the current study, age-related changes in sensory cortical gamma were studied using the auditory steady-state response (ASSR), indexing cortical activity entrained to a periodic auditory stimulus. A large sample (n = 188) aged 8-22 years had electroencephalography recording of ASSR during 20-, 30-, and 40-Hz click trains, analyzed for evoked amplitude, phase-locking factor (PLF) and cross-frequency coupling (CFC) with lower frequency oscillations. Both 40-Hz evoked power and PLF increased monotonically from 8 through 16 years, and subsequently decreased toward ages 20-22 years. CFC followed a similar pattern, with strongest age-related modulation of 40-Hz amplitude by the phase of delta oscillations. In contrast, the evoked power, PLF and CFC for the 20- and 30-Hz stimulation were distinct from the 40-Hz condition, with flat or decreasing profiles from childhood to early adulthood. The inverted U-shaped developmental trajectory of gamma oscillations may be consistent with interacting maturational processes-such as increasing fast GABA inhibition that enhances gamma activity and synaptic pruning that decreases gamma activity-that may continue from childhood through to adulthood.

Concomitant off-pump coronary artery bypass grafting results in improved in-hospital outcomes for patients with ischemic mitral regurgitation undergoing surgery

OBJECTIVE

Surgical management of ischemic mitral regurgitation (IMR) has primarily consisted of revascularization with or without the addition of mitral valve repair or replacement. We hypothesize that performing off-pump coronary artery bypass (OPCAB) grafting before fixing MR improves in-hospital outcomes for patients with IMR undergoing surgery.

METHODS

From January 2000 through December 2010, a total of 96 consecutive patients with moderate or severe IMR, as determined by preoperative echocardiography, underwent on-pump coronary artery bypass grafting (CABG) (n = 66) or OPCAB (n = 30) revascularization with concomitant mitral valve repair or replacement. A retrospective analysis of a prospectively collected cardiac surgery database (PATS; Dendrite Clinical Systems, Oxford, UK) was performed. In addition, medical notes and charts were reviewed for all study patients.

RESULTS

The 2 groups had similar preoperative demographic and EuroSCORE risk-stratification characteristics. The operative mortality rate for the entire cohort was 9.4%. Patients who underwent OPCAB grafting had a lower operative mortality than those who underwent CABG (3.3% versus 12.1%; P = .006). The mean ±SD cardiopulmonary bypass time (82.7 ± 34.7 minutes versus 160.7 ± 45.2 minutes; P < .001) and cross-clamp time (49.0 ± 22.4 minutes versus 103.4 ± 39.5 minutes; P < .001) were significantly shorter in the off-pump group than in the on-pump group. The OPCAB group also had significantly less in-hospital morbidity and shorter stays in the intensive care unit and the hospital.

CONCLUSION

Our analysis shows that OPCAB grafting (compared with conventional CABG) before repairing MR is associated with favorable in-hospital outcomes for patients undergoing surgery for IMR.

Impact of concomitant coronary artery bypass grafting on in-hospital outcome in octogenarians undergoing aortic valve replacement

BACKGROUND AND AIM OF THE STUDY

Abundant data are available reporting excellent in-hospital outcomes after surgical aortic valve replacement (AVR) in octogenarians. However, there is a paucity of studies reporting the in-hospital outcome of concomitant AVR and coronary artery bypass grafting (CABG) in this group of patients. Hence, a comparison was made of the impact of concomitant AVR and CABG versus isolated AVR on in-hospital outcome in octogenarians.

METHODS

Between January 2001 and October 2011, a total of 114 consecutive octogenarians undergoing combined AVR and CABG were compared with a control group of octogenarians (n = 68) undergoing isolated AVR. A retrospective analysis was performed of a prospectively collected cardiac surgery database. In addition, the medical notes and charts of all study patients were reviewed.

RESULTS

The two groups had a similar mean age (AVR 82.3 +/- 2.4 years versus AVR + CABG 82.6 +/- 2.1 years; p = 0.91), demographics and EuroSCORE (AVR 11.4 versus AVR + CABG 13.2; p = 0.12). The aortic cross-clamp and cardiopulmonary bypass times were longer for AVR + CABG patients (p < 0.001). In-hospital mortality (7.4% after isolated AVR, 9.6% after AVR + CABG; p = 0.35 between groups) and major clinical outcomes for the two groups were found to be similar except for an increased need for hemofiltration in AVR + CABG patients (p = 0.02).

CONCLUSION

In-hospital outcomes for concomitant AVR and CABG in octogenarians are comparable to those of isolated AVR, justifying the performance of combined AVR and CABG in this high-risk group of carefully selected patients.

In-Hospital Outcomes of Pedicled Bilateral Internal Mammary Artery Use in Diabetic and Nondiabetic Patients Undergoing Off-Pump Coronary Artery Bypass Grafting: Single-Surgeon, Single-Center Experience

<p><b>Objective:</b> A common perception is that use of pedicled bilateral internal mammary arteries (BIMA) increases the risk of sternal wound complications in diabetic patients undergoing coronary artery bypass grafting (CABG). The purpose of this study was to compare the in-hospital outcomes of CABG using pedicled BIMA in diabetic and nondiabetic patients.</p><p><b>Methods:</b> From September 1998 to September 2010, 390 consecutive diabetic patients and 519 nondiabetic patients underwent isolated off-pump CABG using pedicled BIMA. The 2 groups had comparable preoperative demographics except for a higher prevalence of acute myocardial infarction (18.9% versus 6.1%, <i>P</i> = .01), peripheral vascular disease (17.2% versus 2.7%, <i>P</i> = .001), an ejection fraction <30% (17.7% versus 8.5%, <i>P</i> = .02), and chronic renal failure (4.5% versus 0.9%, <i>P</i> = .01) in the diabetic patients.</p><p><b>Results:</b> The operative mortality rate of the diabetic patients was comparable to that of the nondiabetic patients (2.8% versus 2.1%, <i>P</i> = .87). The in-hospital outcomes, including occurrence of superficial and deep sternal wound infections, were similar except for an increased occurrence of wound infection at the vein harvest site (6.6% versus 1.1%, <i>P</i> = .04) and a need for hemofiltration (11.8% versus 2.1%, <i>P</i> = .02) in the diabetic patients.</p><p><b>Conclusions:</b> Pedicled BIMA use is associated with comparable incidences of sternal wound complications and other outcomes in diabetic patients and nondiabetic patients. Strict perioperative glycemic control, adherence to meticulous closure technique, and postoperative management of surgical wounds can make pedicled BIMA use a default strategy for diabetic patients.</p>

Ten-year outcome analysis of off-pump sequential grafting: single surgeon, single center experience

OBJECTIVES

Despite increasing recognition that off-pump coronary artery bypass surgery and sequential grafting strategy individually are associated with improved outcomes, concerns persist regarding the safety and efficacy of combining these 2 techniques. We compared in-hospital and midterm outcomes for off-pump multivessel sequential and conventional coronary artery bypass grafting.

METHODS

From September 1998 to September 2008, 689 consecutive patients received off-pump multivessel sequential coronary artery bypass grafting performed by a single surgeon. These patients were propensity matched to 689 patients who underwent off-pump coronary artery bypass grafting without sequential anastomoses. A retrospective analysis of prospectively collected perioperative data was performed. In addition, medical notes and charts of all the study patients were reviewed. The mean duration of follow-up was 5.1 ± 2.0 years.

RESULTS

The major in-hospital clinical outcomes in the sequential and control groups were found to be similar. After adjusting for clinical covariates, sequential grafting was not an independent predictor of in-hospital adverse events (odds ratio [OR], 1.18; 95% confidence interval [CI], 0.86-1.50; P = .31), medium-term mortality (hazard ratio [HR], 1.26; 95% CI, 1.06-1.32; P = .92), and readmission to hospital (HR, 1.12; 95% CI, 0.96-1.20; P = .80). Sequential grafting was an independent predictor of receiving more than 3 distal anastomoses (OR, 7.46; 95% CI, 4.27-11.45; P < .0001). Risk-adjusted survival was 89% for sequential grafting patients and 88% for conventional grafting patients (P = .96) during the medium-term follow-up.

CONCLUSION

Our analysis confirms the short- and midterm safety and efficacy of off-pump sequential coronary artery bypass grafting.

Dopamine and gamma band synchrony in schizophrenia--insights from computational and empirical studies

Dopamine modulates cortical circuit activity in part through its actions on GABAergic interneurons, including increasing the excitability of fast-spiking interneurons. Though such effects have been demonstrated in single cells, there are no studies that examine how such mechanisms may lead to the effects of dopamine at a neural network level. With this motivation, we investigated the effects of dopamine on synchronization in a simulated neural network composed of excitatory and fast-spiking inhibitory Wang-Buzsaki neurons. The effects of dopamine were implemented through varying leak K+ conductance of the fast-spiking interneurons and the network synchronization within the gamma band (∼40 Hz) was analyzed. Parametrically varying the leak K+ conductance revealed an inverted-U shaped relationship, with low gamma band power at both low and high conductance levels and optimal synchronization at intermediate conductance levels. We also examined the effects of modulating excitability of the inhibitory neurons more generically using an idealized model with theta neurons, with similar findings. Moreover, such a relationship holds when the external input is both tonic and periodic. Our computational results mirror our empirical study of dopamine modulation in schizophrenia and healthy controls, which showed that amphetamine administration increased gamma power in patients but decreased it in controls. Together, our computational and empirical investigations indicate that dopamine can modulate cortical gamma band synchrony in an inverted-U fashion and that the physiologic effects of dopamine on single fast-spiking interneurons can give rise to such non-monotonic effects at the network level.

Positioning accuracy for lung stereotactic body radiotherapy patients determined by on-treatment cone-beam CT imaging

Stereotactic body radiotherapy for early stage non-small cell lung cancer is an emerging treatment option in the UK. Since relatively few high-dose ablative fractions are delivered to a small target volume, the consequences of a geometric miss are potentially severe. This paper presents the results of treatment delivery set-up data collected using Elekta Synergy (Elekta, Crawley, UK) cone-beam CT imaging for 17 patients immobilised using the Bodyfix system (Medical Intelligence, Schwabmuenchen, Germany). Images were acquired on the linear accelerator at initial patient treatment set-up, following any position correction adjustments, and post-treatment. These were matched to the localisation CT scan using the Elekta XVI software. In total, 71 fractions were analysed for patient set-up errors. The mean vector error at initial set-up was calculated as 5.3 ± 2.7 mm, which was significantly reduced to 1.4 ± 0.7 mm following image guided correction. Post-treatment the corresponding value was 2.1 ± 1.2 mm. The use of the Bodyfix abdominal compression plate on 5 patients to reduce the range of tumour excursion during respiration produced mean longitudinal set-up corrections of -4.4 ± 4.5 mm compared with -0.7 ± 2.6 mm without compression for the remaining 12 patients. The use of abdominal compression led to a greater variation in set-up errors and a shift in the mean value.

Optimal clinical implementation of the siemens virtual wedge

Installation of a modern high-energy Siemens Primus linear accelerator at the Northern Centre for Cancer Treatment (NCCT) provided the opportunity to investigate the optimal clinical implementation of the Siemens virtual wedge filter. Previously published work has concentrated on the production of virtual wedge angles at 15 degrees, 30 degrees, 45 degrees, and 60 degrees as replacements for the Siemens hard wedges of the same nominal angles. However, treatment plan optimization of the dose distribution can be achieved with the Primus, as its control software permits the selection of any virtual wedge angle from 15 degrees to 60 degrees in increments of 1 degrees. The same result can also be produced from a combination of open and 60 degrees wedged fields. Helax-TMS models both of these modes of virtual wedge delivery by the wedge angle and the wedge fraction methods respectively. This paper describes results of timing studies in the planning of optimized patient dose distributions by both methods and in the subsequent treatment delivery procedures. Employment of the wedge fraction method results in the delivery of small numbers of monitor units to the beam's central axis; therefore, wedge profile stability and delivered dose with low numbers of monitor units were also investigated. The wedge fraction was proven to be the most efficient method when the time taken for both planning and treatment delivery were taken into consideration, and is now used exclusively for virtual wedge treatment delivery in Newcastle. It has also been shown that there are no unfavorable dosimetric consequences from its practical implementation.

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS)

The UK national study of magnetic resonance imaging as a method of screening for breast cancer (MARIBS) is in progress. The study design, accrual to date, and related research projects are described. Revised accrual rates and expected recruitment are given. 15 cancers have been detected to date, from a total of 1236 screening measurements. This event rate and the tumour grades reported are compared with recent reports from other studies in women at high risk of breast cancer.

Case report: rhabdomyolysis following grand mal seizures presenting as a delayed and increasingly dense nephrogram

Rhabdomyolysis as a result of major trauma is a well recognized cause of acute renal failure. Non-traumatic rhabdomyolysis causing transient renal impairment may occur following generalized convulsions. We present a case in which rhabdomyolysis following epilepsy was first indicated at urography by a delayed and increasingly dense persistent nephrogram.