Influence of Selective Carbon 1s Excitation on Auger-Meitner Decay in the ESCA Molecule

Two-dimensional spectral mapping is used to visualize how resonant Auger-Meitner spectra are influenced by the site of the initial core-electron excitation and the symmetry of the core-excited state in the trifluoroethyl acetate molecule (ESCA). We observe a significant enhancement of electron yield for excitation of the COO 1s → π* and CF3 1s → σ* resonances unlike excitation at resonances involving the CH3 and CH2 sites. The CF3 1s → π* and CF3 1s → σ* resonance spectra are very different from each other, with the latter populating most valence states equally. Two complementary electronic structure calculations for the photoelectron cross section and Auger-Meitner intensity are shown to effectively reproduce the site- and state-selective nature of the resonant enhancement features. The site of the core-electron excitation and the respective final state hole locality increase the sensistivity of the photoelectron signal at specific functional group sites. This showcases resonant Auger-Meitner decay as a potentially powerful tool for selectively probing structural changes at specific functional group sites of polyatomic molecules.

Hashimoto's thyroiditis and renal transplant rejection

PURPOSE

Hashimoto's thyroiditis (HT) is a common autoimmune thyroid disorder that can disrupt thyroid function and homeostasis. As HT results from a dysregulated immune system, we hypothesized that these patients might be more susceptible to transplant failure; however, literature on this association is limited. The purpose of this study is to examine the association of HT with the risk of renal transplant failure.

METHODS

We utilized the United States Renal Database System dataset collected from 2005 to 2014 and compared the time from first renal transplant to transplant failure in end-stage renal disease (ESRD) patients with a HT diagnosis to ESRD patients without a HT diagnosis that underwent renal transplant.

RESULTS

A total of 144 ESRD patients had International Classification of Disease-9 claim codes for HT prior to renal transplant, amongst a total cohort of 90,301 renal transplant patients aged 18-100 and meeting criteria. Patients with HT were significantly more likely to be female, white, and to have a diagnosis of cytomegalovirus compared to patients without. ESRD patients with a HT diagnosis that underwent renal transplant had a significantly increased risk of renal transplant failure compared to those ESRD renal transplant patients without an HT diagnosis. There was a significantly increased adjusted hazard ratio for graft failure in patients with a HT diagnosis compared to those without.

CONCLUSION

Thyroid health and HT may play a significant role in the development of the increased risk of renal transplant failure observed in this study. Additional studies are needed to investigate the underlying mechanisms for this association.

Local Anaesthesia for Enzymatic Debridement of Cutaneous Burns: A Prospective Analysis of 27 Cases

Enzymatic debridement (ED) is increasingly used for cutaneous burns. Compared with surgical debridement, ED has better preservation of viable dermis, less blood loss and autografting, however ED is painful. Current recommendations suggest local anaesthesia (LA) is useful for minor burns, but the evidence base is minimal. In our centre, we routinely use LA with good analgesic effect. This study was a single-centre, prospective analysis conducted at the Queen Victoria Hospital (UK). Patients had at least superficial partial thickness burns and received subcutaneous LA prior to ED during a 1-year period (October 2019-September 2020). Pain was assessed using a numeric scale of 1-10, recorded before, during and after the procedure. In total, 27 patients were included (n=17 males) with a median age of 47 (18-88 years). The mean total burn surface area was 1.5% (0.3-5.0). Treated sites included head and neck (1), trunk (5), upper limb (9) and lower limb (16). The most used LAwas bupivacaine 0.25% (n=25), followed by lidocaine 1% (n=2). Some required additional oral analgesia (n=8) or a regional blockade (n=2). Average pain score during debridement was 1.9 We have found LA effective, with favourable pain scores in comparison to previous studies with oral analgesia or regional blockade. LA is quick and easy to perform, as opposed to nerve blocks, which require trained personnel with ultrasound guidance. LA is a useful analgesic for patients with minor cutaneous burns undergoing ED. In some cases, it is sufficient without additional oral analgesia or regional blockade.

Undetected hypertension in primary care – a public health iceberg?

Background

Hypertension is largely asymptomatic and contributes to considerable lifetime cardiovascular morbidity and mortality, costing the NHS £2.1 billion annually. The national prevalence of hypertension is 13.7 % and lack of a national screening programme, despite meeting aspects of the Wilson Junger criteria, adds to delays in detection and treatment. Earlier detection could mitigate future cardiovascular risk. We wanted to understand the potential of detection of prehypertension in primary care to see if this fits the Wilson and Junger criteria for a screening programme.

Methods

GP records of adult patients n = 2178 with a known diagnosis of hypertension on the hypertension register from a practice population of 10,000 patients (prevalence is 22%.) were analysed for the prevalence of prehypertension systolic 120-139 mm hg and diastolic bp of 80-89. The average length of prehypertension, the time delay in detection and treatment were assessed, alongside the prevalence of clinical and therapeutic inertia.

Results

A retrospective analysis of a sample size of 1809 patients out of 2178 patients (83.1%) with known hypertension across 3 primary care sites over 20 years was undertaken. Of these 1809 patients, we found that 1095 patients (60.5%) were prehypertensive prior to being diagnosed. The mean time interval between detection of prehypertension to a formal hypertension diagnosis was 10.6 years, with a standard deviation of 7.89 years with no variation with age or sex. However, 588 patients (32.5%) did not have readings within the prehypertensive ranges prior to diagnosis and were opportunistically detected. 51 patients (2.82%) never had readings recorded within the prehypertensive range.

Conclusions

Prehypertension predates hypertension by an average of 10.6 years. Offering annual screening nationally to patients of risk groups e.g., those with a family history, obesity, and alcohol excess, would enable earlier detection, treatment, and considerable cost saving.

Key messages

• Prehypertension predates hypertension; therefore, hypertension meets the Wilson Junger criteria for earlier detection by a screening programme, which is lacking in the UK.

• Offering a national scheme to screen for hypertension to those at a higher risk, can only be considered a benefit to the public and should be implemented.

Protocol of trans-Tasman feasibility randomised controlled trial of the Younger Women's Wellness After Breast Cancer (YWWACP) lifestyle intervention

BACKGROUND

Younger women (defined as those < 50 years who are likely pre-menopausal at time of diagnosis) with breast cancer often experience persistent treatment-related side effects that adversely affect their physical and psychological wellbeing. The Women's Wellness After Cancer Program (WWACP) was adapted and piloted in Australia to address these outcomes in younger women. The aims of this feasibility study are to determine (1) the potential to translate the Younger WWACP (YWWACP) intervention to a broader population base in Aotearoa/New Zealand and Australia, and (2) the potential for success of a larger, international, phase ΙΙΙ, randomised controlled trial.

METHODS

This bi-national, randomised, single-blinded controlled trial involves two main study sites in Aotearoa/New Zealand (Kōwhai study) and Australia (EMERALD study). Young women aged 18 to 50 years who completed intensive treatment (surgery, chemotherapy, and/or radiotherapy) for breast cancer in the previous 24 months are eligible. The potential to translate the YWWACP to women in these two populations will be assessed according to several feasibility outcomes. These include examining intervention accessibility, acceptability and uptake; intervention sustainability and adherence; the prevalence components of the intervention in the control group; intervention efficacy; participants' perception of measurement burden; the effectiveness of planned recruitment strategies; and trial methods and procedures. The studies collectively aim to enrol 60 participants in the intervention group and 60 participants in the control group (total = 120 participants).

DISCUSSION

Ethical approval has been received from the Southern Health and Disability Ethics Committee (Kōwhai ref: 19/STH/215), and UnitingCare Human Research Ethics Committee (EMERALD ref: 202103). This study will provide important data on the feasibility of the refined YWWACP in the trans-Tasman context. This study will account for and harmonise cross-country differences to ensure the success of a proposed international grant application for a phase ΙΙΙ randomised controlled trial of this program to improve outcomes in younger women living with breast cancer.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR): Kōwhai ACTRN12620000260921 , registered on 27 February 2020. EMERALD ACTRN12621000447853 , registered on 19 April 2021.

Evaluation of prognostic risk models for postoperative pulmonary complications in adult patients undergoing major abdominal surgery: a systematic review and international external validation cohort study

BACKGROUND

Stratifying risk of postoperative pulmonary complications after major abdominal surgery allows clinicians to modify risk through targeted interventions and enhanced monitoring. In this study, we aimed to identify and validate prognostic models against a new consensus definition of postoperative pulmonary complications.

METHODS

We did a systematic review and international external validation cohort study. The systematic review was done in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We searched MEDLINE and Embase on March 1, 2020, for articles published in English that reported on risk prediction models for postoperative pulmonary complications following abdominal surgery. External validation of existing models was done within a prospective international cohort study of adult patients (≥18 years) undergoing major abdominal surgery. Data were collected between Jan 1, 2019, and April 30, 2019, in the UK, Ireland, and Australia. Discriminative ability and prognostic accuracy summary statistics were compared between models for the 30-day postoperative pulmonary complication rate as defined by the Standardised Endpoints in Perioperative Medicine Core Outcome Measures in Perioperative and Anaesthetic Care (StEP-COMPAC). Model performance was compared using the area under the receiver operating characteristic curve (AUROCC).

FINDINGS

In total, we identified 2903 records from our literature search; of which, 2514 (86·6%) unique records were screened, 121 (4·8%) of 2514 full texts were assessed for eligibility, and 29 unique prognostic models were identified. Nine (31·0%) of 29 models had score development reported only, 19 (65·5%) had undergone internal validation, and only four (13·8%) had been externally validated. Data to validate six eligible models were collected in the international external validation cohort study. Data from 11 591 patients were available, with an overall postoperative pulmonary complication rate of 7·8% (n=903). None of the six models showed good discrimination (defined as AUROCC ≥0·70) for identifying postoperative pulmonary complications, with the Assess Respiratory Risk in Surgical Patients in Catalonia score showing the best discrimination (AUROCC 0·700 [95% CI 0·683-0·717]).

INTERPRETATION

In the pre-COVID-19 pandemic data, variability in the risk of pulmonary complications (StEP-COMPAC definition) following major abdominal surgery was poorly described by existing prognostication tools. To improve surgical safety during the COVID-19 pandemic recovery and beyond, novel risk stratification tools are required.

FUNDING

British Journal of Surgery Society.

P02.01 A strategy to personalize the use of radiation in patients with brain metastasis based on S100A9-mediated resistance

BACKGROUND

Finding effective treatment options for patients with brain metastasis remains an unmet need. Given the limitations imposed by the blood-brain-barrier for systemic approaches, radiotherapy offers a superior ability to access the brain. While clinical practice recently adapted the use of stereotactic radiosurgery (SRS), Whole-Brain-Radiotherapy (WBRT) continuous to be an important treatment option, since many patients present with multifocal lesions or bad performance scores, rendering them ineligible for SRS. Unfortunately, overall survival of patients remains unaffected by radiotherapy. Despite this clinical data, the molecular mechanisms that allow metastatic cells to resist radiotherapy in the brain is unknown.

MATERIAL AND METHODS

We have applied WBRT to experimental brain metastasis from lung and breast adenocarcinoma and validated their resistance in vivo.

RESULTS

An unbiased search to identify potential mediators of resistance identified the S100A9-RAGE-NFκB-JunB pathway. Targeting this pathway genetically reverts the resistance to radiotherapy and increases therapeutic benefits in vivo. In two independent cohorts of brain metastasis from lung and breast adenocarcinoma patients, levels of S100A9 correlate with the response to radiotherapy, offering a novel approach to stratify patients according to their expected benefit. In order to make this biomarker also available for brain metastasis patients receiving palliative WBRT without preceding surgery, we complemented our tumor-specimen based approach with the less invasive detection of S100A9 from liquid biopsies. Here, serum S100A9 also correlated with a worse response to WBRT in brain metastasis patients. Furthermore, we have validated the use of a blood-brain-barrier permeable RAGE inhibitor to restore radio-sensitivity in experimental brain metastasis models in vivo and in patient-derived organotypic cultures of radio-resistant brain metastasis ex vivo.

CONCLUSION

We identified S100A9 as a major mediator of radio-resistance in brain metastasis and offer the molecular framework to personalize radiotherapy by exploiting it as a biomarker and as a therapeutic target, thus maximizing the benefits for the patient.

Pulse Energy and Pulse Duration Effects in the Ionization and Fragmentation of Iodomethane by Ultraintense Hard X Rays

The interaction of intense femtosecond x-ray pulses with molecules sensitively depends on the interplay between multiple photoabsorptions, Auger decay, charge rearrangement, and nuclear motion. Here, we report on a combined experimental and theoretical study of the ionization and fragmentation of iodomethane (CH_{3}I) by ultraintense (∼10^{19}  W/cm^{2}) x-ray pulses at 8.3 keV, demonstrating how these dynamics depend on the x-ray pulse energy and duration. We show that the timing of multiple ionization steps leading to a particular reaction product and, thus, the product's final kinetic energy, is determined by the pulse duration rather than the pulse energy or intensity. While the overall degree of ionization is mainly defined by the pulse energy, our measurement reveals that the yield of the fragments with the highest charge states is enhanced for short pulse durations, in contrast to earlier observations for atoms and small molecules in the soft x-ray domain. We attribute this effect to a decreased charge transfer efficiency at larger internuclear separations, which are reached during longer pulses.

OP0274-PARE EVALUATION OF PATIENT SATISFACTION FOR TELEHEALTH (PHONE AND VIDEO) IN RHEUMATOLOGY OUTPATIENTS DURING COVID-19 PANDEMIC

Background:

Telehealth via phone (TPhone) or video conference (TVideo) in rheumatology has been a topic of interest for many years. Its use was rapidly expanded due to the international public health emergency of coronavirus disease-19 (COVID-19) outbreak in 2020. Australian Medicare Benefits Schedule (MBS) swiftly enabled temporary MBS telehealth items on 13 March 2020, currently extended until 31 March 20211. In the early phase of the COVID-19 pandemic, Antony et al. conducted a single-centre public survey to assess patient perception of rheumatology telehealth. Their results showed that 98.4% of patients consider telehealth acceptable during the pandemic2. It is unclear, however, whether this positive perception persists after patients experience a telehealth. In addition, a survey data in 2019 suggested more than half of Australian rheumatologists work in private practice3. Therefore, inclusion of private patients will better represent patient perception of telehealth.

Objectives:

The aim of this study was to evaluate patient satisfaction with telehealth during the COVID-19 pandemic. This would determine its feasibility to be integrated in future rheumatology outpatient model.

Methods:

A questionnaire containing 30 questions was sent to rheumatology patients who attended telehealth appointments at a level 2 public hospital and a local private clinic between April and May 2020. The questionnaires aimed to obtain information on baseline demographics (sex, age, public or private patient, employment status, visual or auditory impairment), appointment details (TPhone or TVideo, usual arrangement for face-to-face (F2F) appointment, cost effectiveness) and appointment satisfaction using a 5-point Likert scale. Descriptive statistical analysis was conducted.

Results:

The questionnaire was sent to 1452 patients, of which 494 patients responded (34%). Female predominance (77.1%) and a higher proportion of TPhone (79.1%) was seen in the respondents. A majority of patients were existing patients known to the services (90.9%). More than 70% of responses indicated overall satisfaction in specialist care via telehealth, and 88.7% perceived this suitable during a pandemic. Of all respondents, 21.7% were prescribed new medication, and the majority of these patients were confident in taking the new medication after the telehealth appointment. Future acceptability for TPhone was significantly lower in private patients compared to public patients (p= 0.01). Subgroup analysis revealed that higher telehealth satisfaction was associated with needing to take time off work to attend face-to-face appointment (p= 0.02), perception of cost effectiveness (p<0.001) and TVideo (p=0.03).

Conclusion:

This is the first study which included both public and private rheumatology patients to evaluate patient satisfaction for telehealth during the COVID-19 pandemic. Overall high level of satisfaction was seen in telehealth most notably associated with its cost effectiveness. A higher percentage of patients who had TVideo compared to TPhone were receptive to future telehealth via TVideo, supportive of the importance of visual cues. This in turn will have significant administrative and technological burdens to coordinate in comparison to a F2F or TPhone review. This qualitative study provides valuable insight of patient perception of telehealth, which has the potential to compliment the traditional rheumatology outpatient model of care following the pandemic.

References:

[1]COVID-19 Temporary MBS Telehealth Services 2020 [Available from: http://www.mbsonline.gov.au/internet/mbsonline/publishing.nsf/Content/Factsheet-TempBB.

[2]Antony A, Connelly K, De Silva T, Eades L, Tillett W, Ayoub S, et al. Perspectives of Patients With Rheumatic Diseases in the Early Phase of COVID-19. Arthritis Care & Research. 2020;72(9):1189-95.

[3]Association AR. Workforce Survey Exective Summary 2019 2019 [Available from: https://rheumatology.org.au/members/documents/WorkforceSurveyExecutiveSummary-websiteMay2019.pdf.

Acknowledgements:

University of Queensland

Nursing staff at Redcliffe Hospital and Administration officers at Redcliffe & Northside Rheumatology

Disclosure of Interests:

None declared

O28: M6A DEMETHYLASE FTO A POTENTIAL TARGET IN BRAIN METASTATIC BREAST CANCER

Introduction

Brain metastasis (BrM) occurs in 10-30% of patients with advanced breast cancer (BC). BrM is increasing in incidence and confers a poor prognosis. We aimed to investigate the contribution of global epi-transcriptomic alterations in N6-methyladenosine (m6A) RNA-methylation as a therapeutic target in brain metastatic breast cancer.

Method

In preliminary studies we have demonstrated m6A demethylase – FTO as the main contributor to the progression of ER+ breast cancer. Furthermore an association between FTO and reduced disease-free-survival (n=870, p=0.018) was observed. Here we conducted an epigenetic inhibitor screen using two therapeutic agents, ethyl-ester-meclofenamic acid (MA2) and FB23-2 on matched 2D cell line, 3D organoid cultures and patient-derived xenografts (PDX) explant models of brain metastasis.

Result

Upon integration of mapped global RNA methylation landscape with matched proteomic analysis, we observed genome-wide RNA hypo-methylation of key pluripotency genes, including SOX2 and KLF4, as key players underlying tumour progression to the brain.  Genetic and pharmacological inhibition of FTO in novel ex vivo models of BrM significantly reduced protein expression levels of KLF4 and SOX2. Moreover, pharmacological inhibition of FTO with MA2 and FB23-2, inhibited cell proliferation in endocrine-resistant BC and patient BrM cells. We translate our findings to the clinic by demonstrating the efficacy of anti-FTO therapies in several unique PDX and 3D organoid BrM models.

Conclusion

Our results reveal epi-transcriptional remodelling events as a key mechanism in BrM. This study establishes an early role for targeting RNA methylation in the management of disease progression and presents FTO as a potential therapeutic target in BrM.

Take-home message

This study establishes an early role for targeting RNA methylation in the management of disease progression and presents FTO as a potential therapeutic target in brain metastatic breast cancer.

O50: DEVELOPMENT OF A PATIENT-DERIVED TUMOUR ORGANOIDS FROM METASTATIC BREAST CANCER FOR ASSESSMENT OF NOVEL CLINICALLY ACTIONABLE TARGETS

Introduction

Metastatic breast cancer (MBC) is the main source of mortality in breast cancer patients largely due to lack of effective treatments. Our previous results suggest that tumour transcriptional heterogeneity drives therapy resistance and cancer relapse. While traditional in vitro human cancer cell line models have been widely used for disease modelling, they do not faithfully recapitulate the pathophysiology of MBC.

Method

In this study we developed patient-derived tumour organoid cultures from frozen patient-derived (PDX) models of MBC. Using those models we performed preclinical drug screening of investigational and FDA approved therapeutics previously uncovered by us as potentially clinically actionable in MBC.

Result

Our results reveal high heterogeneity in the responses to various targeted therapies among tested MBC organoids, which makes them a valuable tool for studying intra-tumor heterogeneity and drug response. Moreover, drug screening identified a divergent set of the breast to brain metastatic MBC organoids that showed high sensitivity to a new class of tyrosine kinase receptors, RET.

Conclusion

Taken together, our novel MBC models and methodology applied here provides an important modelling tool to assess the contribution of intra-tumour heterogeneity and microenvironment to drug response as they recapitulate the cellular, structural and biochemical complexity previously observed in our genomic characterisation of MBCs. Application of this type of translational research will enhance the development of new targeted precision medicine strategies and prelude stratification for clinical trials. Abbreviations MBC- Metastatic Breast Cancer; PDX- Patient-Derived Xenografts; FDA- Food and Drug Administration; RET- Receptor Tyrosine Kinase

Take-home message

Patient-derived tumour organoid cultures provide an important modelling tool to assess the contribution of intra-tumour heterogeneity and microenvironment to drug response as they recapitulate the cellular, structural and biochemical complexity previously observed in genomic characterisation of metastatic breast cancer.

SURGICAL EDUCATION AND TRAINING

Safety and efficacy analysis of pembrolizumab dosing patterns in patients with advanced melanoma and non-small cell lung cancer

AIM

To evaluate the impact of discrepancy between prescribed and recommended fixed 200 mg dose (P-F discrepancy) on immune-related adverse events (irAEs) and treatment efficacy in patients with advanced melanoma and NSCLC.

METHODS

This retrospective study included 177 patients with advanced melanoma or non-small cell lung cancer (NSCLC) who received at least one cycle of single-agent pembrolizumab. We defined P-F discrepancy as the differences between prescribed pembrolizumab dose and 200 mg recommended dose, expressed in percentages. Our primary outcome was immune-related adverse events (irAEs), and our secondary outcomes included overall survival (OS) and progression free survival (PFS).

RESULTS

The median P-F discrepancy was -21.5%, with the 25th and 75th percentile at -32% and -5.0% respectively. ROC curve analyses did not show any optimal cutoffs to prognosticate irAEs (AUC = 0.558 for all patients) or cancer mortality (AUC = 0.583 for melanoma; AUC = 0.539 for NSCLC) in either cancer type. Separate multivariable Cox analyses suggested no statistically significant association between P-F discrepancy and overall survival in patients with melanoma (HR 1.012, 95%CI 0.987-1.038, P = 0.362) or NSCLC (HR 0.998, 95%CI 0.978-1.019, P = 0.876).

CONCLUSION

There was no optimal pembrolizumab cut-off point to predict irAEs or treatment efficacy. We supported the use of weight-based pembrolizumab dosing, given the potential cost-saving and no differences in terms of irAEs or treatment efficacy in patients with advanced melanoma or NSCLC. Future studies on province- or national-level would be important to validate our findings.

Resonant Inelastic X-Ray Scattering Reveals Hidden Local Transitions of the Aqueous OH Radical

Resonant inelastic x-ray scattering (RIXS) provides remarkable opportunities to interrogate ultrafast dynamics in liquids. Here we use RIXS to study the fundamentally and practically important hydroxyl radical in liquid water, OH(aq). Impulsive ionization of pure liquid water produced a short-lived population of OH(aq), which was probed using femtosecond x-rays from an x-ray free-electron laser. We find that RIXS reveals localized electronic transitions that are masked in the ultraviolet absorption spectrum by strong charge-transfer transitions-thus providing a means to investigate the evolving electronic structure and reactivity of the hydroxyl radical in aqueous and heterogeneous environments. First-principles calculations provide interpretation of the main spectral features.

Impact of contouring variability on oncological PET radiomics features in the lung

Radiomics features extracted from oncological PET images are currently under intense scrutiny within the context of risk stratification for a variety of cancers. However, the lack of robustness assessment poses problems for their application across institutions and for broader patient populations. The objective of the current study was to examine the extent to which radiomics parameters from oncological PET vary in response to manual contouring variability in lung cancer. Imaging data employed in the study consisted of 26 PET scans with lesions in the lung being created through the use of an anthropomorphic phantom in conjunction with Monte Carlo simulations. From each of the simulated lesions, 25 radiomics features related to the gray-level co-occurrence matrices (GLCOM), gray-level size zone matrices (GLSZM), and gray-level neighborhood difference matrices (GLNDM) were extracted from ground truth contour and from manual contours provided by 10 raters in regard to four intensity discretization schemes with number of gray levels of 32, 64, 128, and 256, respectively. The impact of interrater variability in tumor delineation upon the agreement between raters on radiomics features was examined via interclass correlation and leave-p-out assessment. Only weak and moderate correlations were found between segmentation accuracy as measured by the Dice coefficient and percent feature error from ground truth for the vast majority of the features being examined. GLNDM-based texture parameters emerged as the top performing category of radiomcs features in terms of robustness against contouring variability for discretization schemes engaging number of gray levels of 32, 64, and 128 while GLCOM-based parameters stood out for discretization scheme engaging 256 gray levels. How and to what extent interrater reliability of radiomics features vary in response to the number of raters were largely feature-dependent. It was concluded that impact of contouring variability on PET-based radiomics features is present to varying degrees and could be experienced as a barrier to convey PET-based radiomics research to clinical relevance.

Observation of the fastest chemical processes in the radiolysis of water

Elementary processes associated with ionization of liquid water provide a framework for understanding radiation-matter interactions in chemistry and biology. Although numerous studies have been conducted on the dynamics of the hydrated electron, its partner arising from ionization of liquid water, H2O+, remains elusive. We used tunable femtosecond soft x-ray pulses from an x-ray free electron laser to reveal the dynamics of the valence hole created by strong-field ionization and to track the primary proton transfer reaction giving rise to the formation of OH. The isolated resonance associated with the valence hole (H2O+/OH) enabled straightforward detection. Molecular dynamics simulations revealed that the x-ray spectra are sensitive to structural dynamics at the ionization site. We found signatures of hydrated-electron dynamics in the x-ray spectrum.

Effects of Preparatory Coaching and Home Practice for Deep Inspiration Breath Hold on Cardiac Dose for Left Breast Radiation Therapy

AIMS

Deep inspiration breath hold (DIBH) reduces cardiac radiation exposure by creating cardiac-chest wall separation in breast cancer radiotherapy. DIBH requires sustaining chest wall expansion for up to 40 s and involves complex co-ordination of thoraco-abdominal muscles, which may not be intuitive to patients. We investigated the effect of in-advance preparatory DIBH coaching and home practice on cardiac doses.

MATERIALS AND METHODS

Successive patients from 1 February 2015 to 31 December 2016 with left-sided breast cancer who underwent tangential field radiotherapy utilising the DIBH technique were included. The study cohort consisted of patients treated by a physician who routinely provided DIBH coaching and home practice instructions at least 5 days before simulation. The control group included non-coached patients under another physician's care. Minimum, maximum and mean cardiac doses and V5, V10 and V30 from DIBH and free breathing simulation computed tomography scans were obtained from the planning system. DIBH and free breathing cardiac doses and volume exposures were compared between the coached and non-coached groups using the two-sample t-test, Fisher's exact test and the Mann-Whitney U-test.

RESULTS

Twenty-seven coached and 42 non-coached patients were identified. The DIBH maximum cardiac dose was lower in coached patients at 13.1 Gy compared with 19.4 Gy without coaching (P = 0.004). The percentage cardiac volume exposure in DIBH was lower in coached patients; the DIBH V10 was 0.5% without coaching and 0.1% with coaching (P = 0.005). There was also a trend towards lower DIBH V5 in the coached group compared with the non-coached group (1.2% versus 1.9%, P = 0.071). No significant differences in patient cardiopulmonary comorbidity factors that might influence cardiac doses were found between the groups.

CONCLUSIONS

Our results suggest that cardiac dose sparing can potentially be further improved with a 5 day regimen of preparatory DIBH coaching and in-advance home practice before simulation. These hypothesis-generating findings should be confirmed in a larger study.

Variability in sleep disturbance, physical activity and quality of life by level of depressive symptoms in women with Type 2 diabetes

AIMS

To examine (1) the prevalence of depressive symptoms in women with Type 2 diabetes, (2) the associations between depressive symptoms and the following dependent variables: sleep disturbance; physical activity; physical health-related; and global quality of life, and (3) the potential moderating effects of antidepressants and optimism on the relationship between depressive symptoms and dependent variables.

METHODS

Participants in the Women's Health Initiative who had Type 2 diabetes and data on depressive symptoms (N=8895) were included in the analyses. In multivariable linear regression models controlling for sociodemographic, medical and psychosocial covariates, we examined the main effect of depressive symptoms, as well as the interactions between depressive symptoms and antidepressant use, and between depressive symptoms and optimism, on sleep disturbance, physical activity, physical health-related quality of life; and global quality of life.

RESULTS

In all, 16% of women with Type 2 diabetes reported elevated depressive symptoms. In multivariable analyses, women with depressive symptoms had greater sleep disturbance (P<0.0001) and lower global quality of life (P<.0001). We found evidence of significant statistical interaction in the models for quality-of-life outcomes: the increased risk of poor physical health-related quality of life associated with antidepressant use was stronger in women without vs with depressive symptoms, and the association between greater optimism and higher global quality of life was stronger in women with vs without depressive symptoms.

CONCLUSIONS

To improve health behaviours and quality of life in women with Type 2 diabetes, sociodemographic and medical characteristics may identify at-risk populations, while psychosocial factors including depression and optimism may be important targets for non-pharmacological intervention.

Protocol for a Randomised controlled trial to Evaluate the effectiveness and cost benefit of prescribing high dose FLuoride toothpaste in preventing and treating dEntal Caries in high-risk older adulTs (reflect trial)

BACKGROUND

Dental caries in the expanding elderly, predominantly-dentate population is an emerging public health concern. Elderly individuals with heavily restored dentitions represent a clinical challenge and significant financial burden for healthcare systems, especially when their physical and cognitive abilities are in decline. Prescription of higher concentration fluoride toothpaste to prevent caries in older populations is expanding in the UK, significantly increasing costs for the National Health Services (NHS) but the effectiveness and cost benefit of this intervention are uncertain. The Reflect trial will evaluate the effectiveness and cost benefit of General Dental Practitioner (GDP) prescribing of 5000 ppm fluoride toothpaste and usual care compared to usual care alone in individuals 50 years and over with high-risk of caries.

METHODS/DESIGN

A pragmatic, open-label, randomised controlled trial involving adults aged 50 years and above attending NHS dental practices identified by their dentist as having high risk of dental caries. Participants will be randomised to prescription of 5000 ppm fluoride toothpaste (frequency, amount and duration decided by GDP) and usual care only. 1200 participants will be recruited from approximately 60 dental practices in England, Scotland and Northern Ireland and followed up for 3 years. The primary outcome will be the proportion of participants receiving any dental treatment due to caries. Secondary outcomes will include coronal and root caries increments measured by independent, blinded examiners, patient reported quality of life measures, and economic outcomes; NHS and patient perspective costs, willingness to pay, net benefit (analysed over the trial follow-up period and modelled lifetime horizon). A parallel qualitative study will investigate GDPs' practises of and beliefs about prescribing the toothpaste and patients' beliefs and experiences of the toothpaste and perceived impacts on their oral health-related behaviours.

DISCUSSION

The Reflect trial will provide valuable information to patients, policy makers and clinicians on the costs and benefits of an expensive, but evidence-deficient caries prevention intervention delivered to older adults in general dental practice.

TRIAL REGISTRATION

ISRCTN: 2017-002402-13 registered 02/06/2017, first participant recruited 03/05/2018. Ethics Reference No: 17/NE/0329/233335. Funding Body: Health Technology Assessment funding stream of National Institute for Health Research. Funder number: HTA project 16/23/01. Trial Sponsor: Manchester University NHS Foundation Trust, Oxford Road, Manchester, M13 9WL. The Trial was prospectively registered.

Abstract P6-05-02: Identification of microRNAs differentially expressed in brain metastasis secondary to breast cancer

Background: Despite sequential improvements in the adjuvant treatment of breast cancer (BC), recurrence and metastasis remains a major clinical problem and in particular, brain metastasis (BCBM). A number of microRNAs (miRNAs) have been linked to the metastatic process in BC, but to date there is limited work on the microRNAs involved in BCBM. The current study aim to identify differentially expressed miRNAs within primary breast cancer who did not recur (BCNR) versus primary BC cases which did recur (BCR) and their matched BCBM cases.

Methods: Formalin-fixed paraffin-embedded (FFPE) material was collected of 12 primary BCNRs from the Liverpool tissue bank and of 40 paired primary BCR samples and their matched BCBM from the Walton Research Tissue Bank and RCSI National Breast Cancer Bioresource. miRNA was extracted (Qiagen miRNeasy FFPE kit) and profiled using the NanoString™ nCounter™ miRNA Expression Assay (Human v3 miRNA). The differentially expressed miRNAs between BCNR versus BCR and BCR versus their matched BCBM were identified by significance of microarray analysis (SAM) on the MeV4.9 software. Pathway analysis was performed using the DIANA-mirPath v3.0 software and the Ingenuity Pathway Analysis (IPA) to identify a network of genes/pathways regulated by the differentially expressed miRNAs.

Results: 12 BCNR and 30 matched pairs of BCR and BCBM passed the quality control and normalisation processes. Principal component analysis (PCA) performed on 166 miRNAs after QC/normalisation clearly distinguishes the BCNR and the primary BCR from the matched BCBM cases, whereas SAM revealed 58 differentially expressed miRNAs with a 10% FDR (false discovery rate) and an absolute log2 fold-change (FC) &gt;1 between BCNR and BCR and 11 between the matched BCs and BCBMs. Pathway clustering revealed that these differentially expressed miRNAs (10% FDR, log2FC&gt;1) within both BCNR vs BCR and BCR vs BCBM cohorts are highly enriched for genes involved in extracellular matrix (ECM)-receptor interactions, proteoglycans, adherens junctions, TGF-β, p53 and Hippo signalling. IPA identified a network of genes, implicated in the processes of breast cancer invasion and metastasis, regulated by the identified miRNAs, such as, TWIST, MET, TP53, MYC, EZH2, ZEB1, TAGLN and BIRC5. Four of the significantly differentially expressed miRNAs, hsa-miR-132-3p, hsa-miR-199a-5p, hsa-miR-150-5p and hsa-miR-155-5p were present within both cohorts (BCNR vs BCR and BCR vs BCBM) and regulate genes involved in Hippo and TGF-β signalling (DIANA-mirPath v3.0 analysis: p=5.23x10-08 and p=2.67x10-07 respectively).

Conclusion: The current study, utilising a large cohort of paired BCR and BCBM cases, provides novel insight into the molecular mechanisms and role of miRNAs in BCBM. Four miRNAs (hsa-miR-132-3p, hsa-miR-199a-5p, hsa-miR-150-5p and hsa-miR-155-5p) in particular could be potentially used to identify patients with increased risk of developing brain metastasis and help facilitate the development of specific treatments for BCBM, which to date have proved elusive. The miRNAs identified require further exploration as potential biomarkers as well as novel therapeutic targets.

Citation Format: Giannoudis A, Clarke K, Zakaria R, Vareslija D, Farahani M, Rainbow L, Platt-Higgins A, Ruthven S, Brougham K, Rudland PS, Jenkinson MD, Young L, Falciani F, Palmieri C. Identification of microRNAs differentially expressed in brain metastasis secondary to breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P6-05-02.

Abstract P5-04-12: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Charmsaz S, Doherty B, Cocchiglia S, Bolger J, Vareslija D, McCartan D, Hill A, Young L. Withdrawn [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-04-12.

A call to greater inclusion of gerodontology in the dental curriculum: A narrative review

AIM

This literature review explores the need for greater prominence of gerodontology in the undergraduate dental curriculum, focusing on the significance of gerodontology for dental students on clinical placements.

BACKGROUND

As Australia's population ages the number of dentate older people is increasing. An assessment of the dental profession's preparedness, including that of future providers, is needed to ensure that this public health issue is addressed.

METHODS

A database search was performed in MEDLINE (Ovid), CINAHL and JCU OneSearch. Of the 41 articles identified, 31 were selected for review using a narrative approach.

DISCUSSION

Of the 31 articles reviewed, 12 were Australian, 9 North American and 5 European. Five overarching themes were identified, including preparedness for residential aged care facilities; barriers to oral health services provision; attitudes to aged care; gerodontology as part of a dental school curriculum and service-based learning.

CONCLUSION

There are differences in the gerodontology curricula of dental schools, with a wide variation of clinical exposure to older patients. There is evidence that exposure to gerodontology curriculum prior to treating older people may help dental students feel more prepared for managing patients in aged care. The current marginal status of gerodontology in dental school curricula is in need of review.

Cell-Type-Specific Splicing of Piezo2 Regulates Mechanotransduction

Piezo2 is a mechanically activated ion channel required for touch discrimination, vibration detection, and proprioception. Here, we discovered that Piezo2 is extensively spliced, producing different Piezo2 isoforms with distinct properties. Sensory neurons from both mice and humans express a large repertoire of Piezo2 variants, whereas non-neuronal tissues express predominantly a single isoform. Notably, even within sensory ganglia, we demonstrate the splicing of Piezo2 to be cell type specific. Biophysical characterization revealed substantial differences in ion permeability, sensitivity to calcium modulation, and inactivation kinetics among Piezo2 splice variants. Together, our results describe, at the molecular level, a potential mechanism by which transduction is tuned, permitting the detection of a variety of mechanosensory stimuli.

Dataset on the kinetics of the inhibition of PTP1B by the flavonoids and pheophytin A from Allophylus cominia

The data presented in this article are related to the research article under the title “in vitro anti-diabetic activity of flavonoids and pheophytins from Allophylus cominia Sw. on PTP1B, DPPIV, alpha-glucosidase and alpha-amylase enzymes” (Semaan et al., 2017) [3]. This article defines the kinetics of inhibition of flavonoids and pheophytin A extracts from A. cominia which showed an inhibition of the PTP1B enzyme activity. The main reason to make these results public is to confirm that this study was followed up and no more experiments are needed, also to confirm that these compounds can be reported as PTP1B inhibitors.

The use of infrared thermography for detecting digital dermatitis in dairy cattle: What is the best measure of temperature and foot location to use?

Lameness in dairy cattle is a persistent problem, indicating pain caused by underlying disease states and is associated with reduced milk yields. Digital dermatitis is a common cause of lameness. Thermal imaging is a technique that may facilitate early detection of this disease and has the potential for use in automated detection systems. Previous studies with thermal imaging have imaged either the heels or the coronary band of the foot and typically only used the maximum temperature (Max) value as the outcome measure. This study investigated the utility of other statistical descriptors: 90th percentile (90PCT), 95th percentile (95PCT), standard deviation (SD) and coefficient of variation (CoV) and compared the utility of imaging the heel or coronary band. Images were collected from lame and healthy cows using a high-resolution thermal camera. Analyses were done at the cow and foot level. There were significant differences between lame and healthy feet detectable at the heels (95th percentile: P<0.05; SD: P<0.05) and coronary band (SD: P<0.05). Within lame cows, 95PCT values were higher at the heel (P<0.05) and Max values were higher at the coronary band (P<0.05) in the lame foot compared to the healthy foot. ROC analysis showed an AUC value of 0.72 for Max temperature and 0.68 for 95PCT at the heels. It was concluded that maximum temperature is the most accurate measure, but other statistical descriptors of temperature can be used to detect lameness. These may be useful in certain contexts, such as where there is contamination. Differentiation of lame from healthy feet was most apparent when imaging the heels.

In vitro anti-diabetic effect of flavonoids and pheophytins from Allophylus cominia Sw. on the glucose uptake assays by HepG2, L6, 3T3-L1 and fat accumulation in 3T3-L1 adipocytes

BACKGROUND AND PURPOSE

Based on ethno-botanical information collected from diabetic patients in Cuba and firstly reported inhibition of PTP1B and DPPIV enzymes activities, Allophylus cominia (A. cominia) was identified as possible source of new drugs that could be used for the treatment of type 2 diabetes mellitus (T2-DM).

EXPERIMENTAL APPROACH

in this study, the activity of the characterised extracts from A. cominia was tested on the glucose uptake using HepG2 and L6 cells, 3T3-L1 fibroblasts and adipocytes as well as their effect on the fat accumulation using 3T3-L1 adipocytes.

KEY RESULTS

on 2-NBDG glucose uptake assay using HepG2 and L6 cells, extracts from A. cominia enhanced insulin activity by increasing glucose uptake. On HepG2 cells Insulin EC₅₀ of 93 ± 21nM decreased to 13 ± 2nM in the presence of the flavonoids mixture from A.cominia. In L6 cells, insulin also produced a concentration-dependent increase with an EC₅₀ of 28.6 ± 0.7nM; EC₅₀ decreased to 0.08 ± 0.02nM and 5 ± 0.9nM in the presence of 100μg/ml of flavonoids and pheophytins mixtures, respectively. In 3T3-L1 fibroblasts, insulin had an EC₅₀ of >1000nM that decreased to 38 ± 4nM in the presence of the flavonoids extract. However, in adipocytes, insulin produced a significant concentration-dependent increase and an EC₅₀ of 30 ± 8nM was a further confirmation of the insulin responsiveness of the adipocytes to the insulin. At 100µg/ml, flavonoids and pheophytins extracts decreased fat accumulation in 3T3-L1 adipocytes by two folds in comparison to the control differentiated cells (p < 0.05). The crude extract of A. cominia did not show any enhancement of 2-NBDG uptake by 3T3-L1 adipocytes in the presence or absence of 100nM insulin. In addition, in fully differentiated adipocytes, both extracts produced significant decrease in lipid droplets in the cells and no lipid accumulation were seen after withdrawal of the extracts from the cell growth medium. However, there was no effect of both extracts on total protein concentration in cells as well as on Glut-4 transporters.

CONCLUSIONS AND IMPLICATIONS

the pharmacological effects of the extracts from A. cominia observed in experimental diabetic models were shown in this study. A. cominia is potentially a new candidate for the treatment and management of T2-DM.

Abstract GS2-03: Highly recurrent transcriptional remodeling events in advanced endocrine resistant ER-positive breast cancers

BACKGROUND: Although individual cancers are driven by heterogeneous processes, cancer mortality has a near universal cause—therapy resistance, recurrence and metastasis to vital organs. Characterizing more advanced tumors has borne valuable insight into cancer progression, yet studies of longitudinally collected breast cancer specimens are scarce given lengthy periods of cancer dormancy. In this study, we aimed to create the most comprehensive characterization of gene expression alterations to date between patient-matched pairs of primary and advanced ER-positive breast cancers.

MATERIALS/METHODS: Hybrid-capture RNA-sequencing was performed on 50 patient-matched pairs of primary and advanced ER-positive tumors from various recurrence sites (9 brain, 11 bone, 3 GI, 10 ovary, 17 local). Time to recurrence was up to 14.1 years with a median of 3.4 years. A shared variant analysis confirmed all paired samples were patient-matched. 1,380 cancer-related genes were analyzed for outlier expression fold-changes in matched recurrences versus primary tumors. Pair-specific, outlier fold-change thresholds were defined as Q1/Q3 +/- [1.5 X IQR]; using each pairs' fold-change values across all genes as the distribution. These discrete, longitudinal transcriptional remodeling events (LTREs) were assessed for recurrence across all sites and analyzed for enrichments within specific cohorts (Fisher's exact tests), such as locoregional vs. distant recurrences. To determine if LTREs represent acquired vulnerabilities, ex vivo and in vivo experiments targeting a recurrent, druggable LTRE gain of RET was performed.

RESULTS: The majority of advanced cancers were transcriptionally similar to patient-matched primaries with 23 of 33 distant metastases retaining PAM50 assignments of the matched primary—shifts to HER2 (n=4, 12%) or Luminal B (n=5, 15%) subtypes accounted for most metastatic discordances. Despite this intrinsic conservation, remarkably recurrent gene-level LTRE gains and losses were observed in advanced disease. Recurrent LTRE gains included NCAM1 [42%], FGFR4 [40%], IBSP [36%], ROBO2 [36%] and SPP1 [30%]. Notable LTRE losses included RELN [42%] and ESR1 [26%]. NCAM1 LTREs showed the most significant enrichments (p &lt; 0.001) in distant disease (20 of 33, 61%) versus locoregional disease (1 of 17, 6%). A prominent LTRE enriched in brain metastasis (BrM) was RET (p-value = 0.003), expression of which showed outlier gains in 56% of ER-positive BrM. Marked anti-tumor activity was demonstrated with the RET inhibitor cabozantinib in ex vivo explant cultures of patient resected BrMs (n=3) and a BrM patient-derived xenograft.

CONCLUSIONS: Taken together, these results demonstrate profound, recurrent and metastatic site-specific LTREs in advanced breast cancers, which may be essential to our understanding of endocrine-therapy resistance and metastasis. Although current emphasis for longitudinal clinical profiling of tumors is on DNA-level alterations, these results suggest LTREs as a compelling, shared mechanism of cancer progression. Given remarkably high recurrence rates of specific LTREs across multiple cohorts, further preclinical and clinical investigations of LTREs are demanded, especially considering some (i.e. FGFR4 and RET) are readily druggable.

Citation Format: Priedigkeit N, Vareslija D, Basudan A, Watters RJ, Lucas PC, Davidson NE, Blohmer J-U, Denkert C, Machleidt A, Heppner BI, Brufsky AM, Oesterreich S, Young L, Lee AV. Highly recurrent transcriptional remodeling events in advanced endocrine resistant ER-positive breast cancers [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS2-03.

Abstract P5-10-02: High expression of BAD, PUMA, BOK and TRADD mRNA is associated with higher overall survival in ER+ and PR+ breast cancer patients

Background: Apoptosis signalling is controlled by a complex interaction of pro- and anti-apoptotic BCL2 proteins and its dysregulation is believed to be a major contributor to therapy responses and resistance in cancer. We previously demonstrated that inhibition of cell death in cancer cell is associated to poor outcome in colorectal cancer (Lindner et al., Cancer Res, 2012) and to lower cell death in triple negative breast cancer (TNBC) cells in vitro (Lucantoni et al., in review). In ER+ breast cancer, the anti-apoptotic protein BCL2 is commonly overexpressed, but its expression is associated with improved clinical outcome. The aim of this study was to assess whether system modelling of BCL2 protein interactions stratifies low- and high-risk breast cancer patients, and to determine the contribution of apoptosis signalling in different molecular subtypes of breast cancer.

Methods: Protein levels of BAK, BAX, BCL2 and BCL(X) were determined in fresh frozen, TNBC samples from the BREAST-PREDICT Irish Cancer Society Collaborative Research Centre cohort, using HeLa cells as standard in which absolute protein levels were previously determined. Clinical, protein level and gene expression datasets of 845 invasive breast carcinoma patients were accessed from The Cancer Genome Atlas project, and BCL2 protein profiles were calculated by linear regression based on the BREAST-PREDICT cohort. In both cohorts, profiles were used to calculate the stress dose required to induce mitochondrial apoptosis (η).

Results: In contrast to experiments with TNBC cells in which a high η indicated lower rates of cell death in vitro (Lucantoni et al., in review), we found that in breast cancer patients, η ≤ 0 was associated with lower overall survival (OS) compare to η &gt; 0 (HR 2.1, 95%CI 1.3-3.3, p &lt; 0.01). η &gt; 0 was associated with lower levels of cleaved caspase 7 compared to η ≤ 0 (ANOVA & Tukey post-hoc; p &lt; 0.1). Cleaved caspase 7 levels &gt; mean were associated with improved OS compared to levels ≤ mean (HR 0.4, 95%CI 0.3-0.7, p = 0.001). High values of η were significantly associated with lower proliferation in ER/PR+ cancer (ANOVA & Tukey post-hoc; p &lt; 0.01), but not in HER2+ or TNBC. Next we performed hierarchical cluster analysis (ConsensusClusterPlus; Monti et al, Machine Learning, 2003) with 61 additional mRNAs and proteins which are not implemented in our systems modelling approach. We found a subgroup with high BAD, PUMA, BOK and TRADD mRNA expression levels in ER/PR+ breast cancer patients, independently of the value of η. ER/PR+, but not HER2+ or TNBC, patients with an averaged expression of these 4 mRNA &gt; mean had significant higher OS compared with patients with an averaged expression ≤ mean (HR 0.4, 95%CI 0.2-0.9, p = 0.02).

Conclusions: Impairment of apoptosis assessed solely on the levels of BAK, BAX, BCL2 and BCLX(L) proteins were not sufficient as prognostic marker in breast cancer patients. However, our analysis suggest that patients with ER/PR+ cancer cells potentially 'primed' towards apoptosis - via the expression of pro-apoptotic BAD, PUMA, BOK and TRADD - had a more favourable clinical outcome compared to patients with cancer cells lacking this priming.

Citation Format: Lindner AU, Lucantoni F, Vareslija D, Resler A, Gallagher WM, Hill A, Young L, Prehn JHM. High expression of BAD, PUMA, BOK and TRADD mRNA is associated with higher overall survival in ER+ and PR+ breast cancer patients [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P5-10-02.

Hybrid capture-based genomic profiling of circulating tumor DNA from patients with estrogen receptor-positive metastatic breast cancer

BACKGROUND

Genomic changes that occur in breast cancer during the course of disease have been informed by sequencing of primary and metastatic tumor tissue. For patients with relapsed and metastatic disease, evolution of the breast cancer genome highlights the importance of using a recent sample for genomic profiling to guide clinical decision-making. Obtaining a metastatic tissue biopsy can be challenging, and analysis of circulating tumor DNA (ctDNA) from blood may provide a minimally invasive alternative.

PATIENTS AND METHODS

Hybrid capture-based genomic profiling was carried out on ctDNA from 254 female patients with estrogen receptor-positive breast cancer. Peripheral blood samples were submitted by clinicians in the course of routine clinical care between May 2016 and March 2017. Sequencing of 62 genes was carried out to a median unique coverage depth of 7503×. Genomic alterations (GAs) in ctDNA were evaluated and compared with matched tissue samples and genomic datasets of tissue from breast cancer.

RESULTS

At least 1 GA was reported in 78% of samples. Frequently altered genes were TP53 (38%), ESR1 (31%) and PIK3CA (31%). Temporally matched ctDNA and tissue samples were available for 14 patients; 89% of mutations detected in tissue were also detected in ctDNA. Diverse ESR1 GAs including mutation, rearrangement and amplification, were observed. Multiple concurrent ESR1 GAs were observed in 40% of ESR1-altered cases, suggesting polyclonal origin; ESR1 compound mutations were also observed in two cases. ESR1-altered cases harbored co-occurring GAs in PIK3CA (35%), FGFR1 (16%), ERBB2 (8%), BRCA1/2 (5%), and AKT1 (4%).

CONCLUSIONS

GAs relevant to relapsed/metastatic breast cancer management were identified, including diverse ESR1 GAs. Genomic profiling of ctDNA demonstrated sensitive detection of mutations found in tissue. Detection of amplifications was associated with ctDNA fraction. Genomic profiling of ctDNA may provide a complementary and possibly alternative approach to tissue-based genomic testing for patients with estrogen receptor-positive metastatic breast cancer.