Development and validation of the HARMS2-AF lifestyle risk score to predict incident AF

Background

Lifestyle risk factors (RFs) are a modifiable target in atrial fibrillation (AF) management. However, the relative contribution of individual lifestyle RFs to AF incidence has not been described.

Purpose

Development and validation of a novel AF-lifestyle risk score to determine AF risk in the general population.

Methods

The UK Biobank (UKB) is a large prospective cohort with outcomes measured >10 years. In the UKB, we performed regression analysis of AF lifestyle RFs which were then evaluated in a multivariable model and a weighted score was developed. Next, the risk score was externally validated in the Framingham Heart Study (FHS) population. Kaplan-Meier estimates ascertained the 10-year risk of AF development.

Results

In the UKB, AF incidence was 5.3% among 302,926 participants, with a median time to AF 7.3 years (IQR 4.3–9.8). Hypertension, sleep apnoea, male sex, age, obesity (BMI>30 kg/m2), alcohol and smoking were predictive variables (all p<0.001); physical inactivity (OR 1.02,95% CI 0.97–1.10, p=0.3), diabetes (OR 0.98,95% CI 0.91–1.06, p=0.2) and BMI 27–30 kg/m2 (OR 1.02, 95% CI 0.97–1.07, p=0.424) were not significant. The HARMS2-AF score (Figure 1) had similar predictive performance (AUC=0.782, LogLoss 0.178, Brier Score 0.046) to the unweighted regression model (AUC 0.808) in the UKB. Validation in the FHS (AF incidence 6.7% of 7206 participants) maintained excellent predictive performance with an AUC of 0.747 (95% CI 0.724–0.769, Figure 2). A higher HARMS2-AF score (>5 points) was associated with a heightened 10-year AF risk (score 5–9: OR 9.35, score 10–14: OR 33.34).

Conclusions

The HARMS2-AF score is a novel lifestyle risk score which may help identify individuals at risk of AF and assists in general population screening.

Funding Acknowledgement

Type of funding sources: None.

Clinical risk prediction for left atrial appendage thrombus among patients with atrial fibrillation

Background

Exclusion of left atrial appendage thrombus (LAAT) by transoesophageal echocardiography (TOE) is recommended in patients with inadequate anticoagulation prior to direct cardioversion (DCR) or catheter ablation for atrial fibrillation/flutter (AF/AFL). LAAT risk factors in this population remain poorly defined.

Purpose

Determine LAAT predictors in AF/AFL patients undergoing pre-procedural TOE.

Methods

We evaluated available clinical and transthoracic echocardiographic (TTE) parameters in AF/AFL patients undergoing TOE between 1999–2022 in our institution in Melbourne, Australia. Regression analysis identified predictors of LAAT, which were applied to a weighted score developed in the derivation cohort (70%) and validated in the remaining 30%.

Results

Of 627 patients (age 62±12 years, 27% female, AF 84%,AFL 16%, left ventricular ejection fraction (LVEF) 44±20%), 24% had LAAT and 13.8% dense spontaneous echo contrast precluding DCR. Anticoagulation was NOAC 56.5%, warfarin 32.1% and none in 11.4%. In the LAAT cohort, thrombus resolution occurred in 39% on serial transoesophageal imaging with a median time to resolution of 131 days (IQR 54–398).

Diabetes (p=0.004), prior stroke (p=0.009), coronary disease (p=0.015), renal impairment (p<0.001) and CHADS2VASc >2 (73% vs. 55%, p<0.001) were higher in the LAAT cohort. Age (p=0.093), gender (p=0.689), BMI (p=0.828), anticoagulant type (p=0.316) and diabetes (p=0.107) were not univariate predictors, whereas anticoagulation duration (<30 days), creatinine and TTE markers of remodeling (LVEF, LAVI, RVSP and TAPSE) were independent predictors on univariate and multivariate regression; CHADS2VASc was not significant after adjustment (p=0.090). The weighted risk model included continuous (age, creatinine, LVEF, LAVI, TAPSE and RVSP) and categorical (anticoagulation duration) variables with excellent predictive performance: AUC 0.872 (95% CI 0.798–0.946), PPV 91%, NPV 70% and accuracy 80%.

Conclusion

A novel LAAT risk model comprising clinical and echocardiographic parameters enhances risk prediction over CHADS2VASc in AF/AFL and may guide the need for pre-procedural TOE imaging.

Funding Acknowledgement

Type of funding sources: None.

A semiparametric model for between-subject attributes: Applications to beta-diversity of microbiome data

The human microbiome plays an important role in our health and identifying factors associated with microbiome composition provides insights into inherent disease mechanisms. By amplifying and sequencing the marker genes in high-throughput sequencing, with highly similar sequences binned together, we obtain operational taxonomic units (OTUs) profiles for each subject. Due to the high-dimensionality and nonnormality features of the OTUs, the measure of diversity is introduced as a summarization at the microbial community level, including the distance-based beta-diversity between individuals. Analyses of such between-subject attributes are not amenable to the predominant within-subject-based statistical paradigm, such as t-tests and linear regression. In this paper, we propose a new approach to model beta-diversity as a response within a regression setting by utilizing the functional response models (FRMs), a class of semiparametric models for between- as well as within-subject attributes. The new approach not only addresses limitations of current methods for beta-diversity with cross-sectional data, but also provides a premise for extending the approach to longitudinal and other clustered data in the future. The proposed approach is illustrated with both real and simulated data.

Abstract I26: Investigating the immune microenvironment in mouse models of pancreatic cancer

Pancreatic cancer is predicted to become the second most common cause of cancer death in the Western world by ~2025. The focus of our research has been to better understand the disease and identify more effective and targeted therapies, in particular, using genetically engineered mouse models, which develop pancreatic tumors reminiscent of the human disease including development of a complex microenvironment. The pancreatic cancer microenvironment is characterized by significant infiltration of immune cells, but a distinct lack of T cells. Thus, immunotherapies have had little efficacy in PC despite promise in other cancers. Recent data have suggested that genomic instability and increased mutation burden may predict the efficacy of immune checkpoint inhibitors. To investigate this, we have generated a model of APOBEC mutagenesis in pancreatic cancer. The APOBEC family of cytidine deaminase enzymes, whose normal function is to protect from viral infections, have been revealed as drivers of mutation in a variety of human tumors, including pancreatic cancer. We have engineered mice to express Cre-inducible APOBEC3B and crossed these with the KPC genetically engineered mouse model of pancreatic cancer. We find that overexpressing APOBEC3B results in a poorer prognosis in these animals and some changes in the immune microenvironment. We are currently performing genomic and transcriptomic analyses to determine mutational burden and tumor subtype in an effort to identify therapeutic opportunities in patients bearing this signature. In contrast with T cells, recent studies have suggested that B cells may be tumor promoting in pancreatic cancer. However, clinical trials targeting B cells have been conducted recently and the results have been very disappointing. We have now generated an autochthonous model of B-cell depletion and find that B cells are not tumor promoting in this setting. We are now investigating the mechanisms behind this and the microenvironmental differences that are observed in spontaneous versus allograft models.

Citation Format: Karen Pickering, Laura Lapienyte, Saadia Karim, Douglas Strathdee, Owen Sansom, Jen Morton. Investigating the immune microenvironment in mouse models of pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr I26.

A new technique for tensile testing of engineering materials and composites at high strain rates

A new test technique and bespoke apparatus to conduct high strain rate measurements of the tensile response of materials are presented. The new test method is applicable to brittle solids and composites as well as high-performance fibres, yarns and tapes used in composite construction. In this study, the dynamic response of monolithic poly(methyl methacrylate) and unidirectional composites based on Dyneema® tape, Dyneema® SK75 yarn and Kevlar® 49 yarn are explored. The technique allows early force equilibrium and yields valid tensile stress-strain curves, which include part of the elastic material response. The new method also enables investigation of size effects in tape and yarn materials, allowing testing of specimens of arbitrary length.

Abstract 2751: Development of a specific Wee-1 inhibitor

Somatic mutations in the TP53 gene are one of the most frequent alterations in human cancers. The resulting TP53-deficient cancer cells rely on WEE1 to trigger a G2/M arrest, which allows for DNA repair and survival. Inhibition of WEE1 has therefore emerged as an attractive therapeutic strategy to selectively sensitise TP53-deficient tumours to DNA damaging agents. The WEE1 kinase inhibitor adavosertib is the only agent undergoing evaluation in a range of clinical trials to validate this hypothesis. It has also been the tool compound of choice to interrogate WEE1 biology for over a decade.

However, recent reports show adavosertib has antiproliferative single agent activity, which is counter intuitive considering its postulated mode of action. Other studies suggest adavosertib exerts poor kinase selectivity, and inhibits PLK1 with similar potency as WEE1. Since PLK1 is a well-established mitotic regulator with biological functions throughout the cell cycle, its inhibition may contribute to the clinical efficacy and toxicity observed for adavosertib. Other reported WEE1 inhibitors also suffer from low selectivity and single agent toxicity, making then unsuitable tool compounds. There is a clear need to identify a selective Wee1 tool compound.

Using a structure-based drug design approach, we exploited subtle active site differences to identify novel, potent WEE1 inhibitors that display high selectivity over PLK1. These compounds allowed us to demonstrate the distinct effects of WEE1 and PLK1 inhibition on cellular toxicity, and confirm that adavosertib’s single agent efficacy is unlikely to be mediated solely through the inhibition of WEE1. Our ongoing studies aim to provide a WEE1 selective tool compound that more rigorously probes WEE1 biology, and eventually leads to the development of less toxic therapeutic agents.

Citation Format: Mandy Watson, Tom Pesnot, Andrew Scott, Anthony Huxley, Gary Nelson, Montserrat Shelbourne, Jen Morton, Tilly Bingham. Development of a specific Wee-1 inhibitor [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 2751.

Diagnostic Dilemmas and Management of Fulminant Myocarditis

Myocarditis is commonly a diagnosis of exclusion. We report a case of fulminant myocarditis in a patient with cardiogenic shock in whom the initial diagnosis was unclear. Early supportive care including extracorporeal membrane oxygenation and intraaortic balloon pump were instituted. Complete recovery of cardiac function was achieved. This case highlights the difficulty in diagnosing myocarditis and the benefits of early intensive support.

The people living with HIV stigma survey UK 2015: HIV-related sexual rejection and other experiences of stigma and discrimination among gay and heterosexual men

We aim to understand the difference in stigma and discrimination, in particular sexual rejection, experienced between gay and heterosexual men living with HIV in the UK. The People Living with HIV StigmaSurvey UK 2015 recruited a convenience sample of persons with HIV through over 120 cross sector community organisations and 46 HIV clinics to complete an online survey. 1162 men completed the survey, 969 (83%) gay men and 193 (17%) heterosexual men, 92% were on antiretroviral therapy. Compared to heterosexual men, gay men were significantly more likely to report worrying about workplace treatment in relation to their HIV (21% vs. 11%), worrying about HIV-related sexual rejection (42% vs 21%), avoiding sex because of their HIV status (37% vs. 23%), and experiencing HIV-related sexual rejection (27% vs. 9%) in the past 12 months. In a multivariate logistic regression controlling for other sociodemographic factors, being gay was a predictor of reporting HIV-related sexual rejection in the past 12 months (aOR 2.17, CI 1.16, 4.02). Both gay and heterosexual men living with HIV experienced stigma and discrimination in the past 12 months, and this was higher for gay men in terms of HIV-related sexual rejection. Due to the high proportion of men reporting sexual rejection, greater awareness and education of the low risk of transmission of HIV among people on effective treatment is needed to reduce stigma and sexual prejudice towards people living with HIV.

Analysis of soluble or titanium dioxide derived titanium levels in human whole blood: consensus from an inter-laboratory comparison

Exposure to titanium (Ti),viathe ingestion of pigment grade Ti dioxide (TiO₂), is commonplace for westernised populations.

Abstract PR10: CXCR2 Inhibition Suppresses Metastasis and Improves the Response to Immunotherapy in Pancreatic Cancer

PDAC is predicted to become the second commonest cause of cancer death in the western world by 2030. Aggressive invasion and early metastases are characteristic of the disease, and even the few patients eligible for potentially curative resection inevitably develop recurrent or metastatic disease.

We now show that CXCR2 signalling is upregulated in human pancreatic cancer, predominantly in neutrophils at the tumour invasive edge. In mouse models, genetic ablation or inhibition of CXCR2 abrogated metastasis while inhibition also slowed tumorigenesis, particularly when combined with chemotherapy. Depletion of neutrophils also suppressed metastasis, suggesting a key role for CXCR2 in establishing and maintaining the metastatic niche.

Indications from trials thus far suggest that immunotherapy will not work as a single agent strategy in pancreatic cancer patients. Importantly, we find that loss or inhibition of CXCR2 improved T-cell entry and combined inhibition of CXCR2 and PD1 in mice with established disease caused a significant extension of survival.

Thus, our data highlight two novel therapeutic opportunities for PDAC: first the use of CXCR2 inhibitors in surgically-resected patients to prevent recurrence at distant sites, and second, the use of CXCR2 inhibition in combination with immunotherapy in surgically unresectable advanced disease.

This abstract is also being presented as Poster B55

Citation Format: Colin Steele, Saadia Karim, Josh Leach, Peter Bailey, Andrew Biankin, Rob Nibbs, Simon Barry, Owen Sansom, Jen Morton.{Authors}. CXCR2 Inhibition Suppresses Metastasis and Improves the Response to Immunotherapy in Pancreatic Cancer. [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2016 May 12-15; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2016;76(24 Suppl):Abstract nr PR10.

Using VISAR to assess the M-band isotropy in hohlraums

In laser based radiation flow experiments, drive variability can often overwhelm the physics sensitivity that one seeks to quantify. Hohlraums can help by providing a more symmetrized, Planckian-like source. However, at higher temperatures, the hohlraum's actual emission can deviate significantly from a truly blackbody, Lambertian source. At the National Ignition Facility (NIF), Dante provides the best quantification of hohlraum output. Unfortunately, limited diagnostic access coupled with NIF's natural symmetry does not allow for Dante measurements at more than two angles. As part of the CEPHEUS campaign on NIF, proof-of-principle experiments to better quantify the gold M-band isotropy were conducted. These experiments positioned beryllium/aluminum mirrors at differing angles, offset from the hohlraum. Filtering removes the thermal emission of the hohlraum and the remaining M-band radiation is preferentially absorbed in the aluminum layer. The subsequent hydrodynamic motion is measured via VISAR. Although indirect, this M-band measurement can be made at any angle.