A Novel C-C Chemoattractant Cytokine (Chemokine) Receptor 6 (CCR6) Antagonist (PF-07054894) Distinguishes between Homologous Chemokine Receptors, Increases Basal Circulating CCR6+ T Cells, and Ameliorates Interleukin-23-Induced Skin Inflammation

Blocking chemokine receptor C-C chemoattractant cytokine (chemokine) receptor (CCR) 6-dependent T cell migration has therapeutic promise in inflammatory diseases. PF-07054894 is a novel CCR6 antagonist that blocked only CCR6, CCR7, and C-X-C chemoattractant cytokine (chemokine) receptor (CXCR) 2 in a β-arrestin assay panel of 168 G protein-coupled receptors. Inhibition of CCR6-mediated human T cell chemotaxis by (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) was insurmountable by CCR6 ligand, C-C motif ligand (CCL) 20. In contrast, blockade of CCR7-dependent chemotaxis in human T cells and CXCR2-dependent chemotaxis in human neutrophils by PF-07054894 were surmountable by CCL19 and C-X-C motif ligand 1, respectively. [3H]-PF-07054894 showed a slower dissociation rate for CCR6 than for CCR7 and CXCR2 suggesting that differences in chemotaxis patterns of inhibition could be attributable to offset kinetics. Consistent with this notion, an analog of PF-07054894 with fast dissociation rate showed surmountable inhibition of CCL20/CCR6 chemotaxis. Furthermore, pre-equilibration of T cells with PF-07054894 increased its inhibitory potency in CCL20/CCR6 chemotaxis by 10-fold. The functional selectivity of PF-07054894 for inhibition of CCR6 relative to CCR7 and CXCR2 is estimated to be at least 50- and 150-fold, respectively. When administered orally to naïve cynomolgus monkeys, PF-07054894 increased the frequency of CCR6+ peripheral blood T cells, suggesting that blockade of CCR6 inhibited homeostatic migration of T cells from blood to tissues. PF-07054894 inhibited interleukin-23-induced mouse skin ear swelling to a similar extent as genetic ablation of CCR6. PF-07054894 caused an increase in cell surface CCR6 in mouse and monkey B cells, which was recapitulated in mouse splenocytes in vitro. In conclusion, PF-07054894 is a potent and functionally selective CCR6 antagonist that blocks CCR6-mediated chemotaxis in vitro and in vivo. SIGNIFICANCE STATEMENT: The chemokine receptor, C-C chemoattractant cytokine (chemokine) receptor 6 (CCR6) plays a key role in the migration of pathogenic lymphocytes and dendritic cells into sites of inflammation. (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) is a novel CCR6 small molecule antagonist that illustrates the importance of binding kinetics in achieving pharmacological potency and selectivity. Orally administered PF-07054894 blocks homeostatic and pathogenic functions of CCR6, suggesting that it is a promising therapeutic agent for the treatment of a variety of autoimmune and inflammatory diseases.

Comparing molecular and computational approaches for detecting viral integration of AAV gene therapy constructs

Many current gene therapy targets use recombinant adeno-associated virus (AAV). The majority of delivered AAV therapeutics persist as episomes, separate from host DNA, yet some viral DNA can integrate into host DNA in different proportions and at genomic locations. The potential for viral integration leading to oncogenic transformation has led regulatory agencies to require investigation into AAV integration events following gene therapy in preclinical species. In the present study, tissues were collected from cynomolgus monkeys and mice 6 and 8 weeks, respectively, following administration of an AAV vector delivering transgene cargo. We compared three different next-generation sequencing approaches (shearing extension primer tag selection ligation-mediated PCR, targeted enrichment sequencing [TES], and whole-genome sequencing) to contrast the specificity, scope, and frequency of integration detected by each method. All three methods detected dose-dependent insertions with a limited number of hotspots and expanded clones. While the functional outcome was similar for all three methods, TES was the most cost-effective and comprehensive method of detecting viral integration. Our findings aim to inform the direction of molecular efforts to ensure a thorough hazard assessment of AAV viral integration in our preclinical gene therapy studies.

148 ORTHOSTATIC HEMODYNAMICS AND ACCELERATED BRAIN AGING

Background

Impaired recovery of blood pressure (BP) in response to standing up is a prevalent condition in older individuals. We evaluated the relationship between the recovery of hemodynamic responses to standing and brain health in adults over 50.

Methods

Participants from The Irish Longitudinal Study on Aging (TILDA) (n=418) performed an active stand challenge while BP and heart rate (HR) were continuously monitored. The recovery of these parameters was determined as the difference in measurements taken at 10 s and 20 s after standing, in relation to the baseline value. The difference between biological and chronological brain age was determined using BrainPAD, a novel validated measure of accelerated brain ageing. The data was fitted using linear regression models, using age, sex, weight, height, cardiac disease prevalence, antihypertensive and antidepressant use, smoking status, standing speed and pulse wave velocity as covariates.

Results

Adjusting for age and sex only, each additional year of BrainPAD was associated with a –0.35 mmHg (95% CI: –0.54 – –0.16, P<.001) change in orthostatic systolic BP recovery. In a fully adjusted model, the regression coefficient was estimated at –0.29 mmHg (95% CI: –0.48 – –0.10, P<.01). Similarly, a year increase in BrainPAD was associated with –0.21 mmHg (95% CI: –0.32– –0.10, P<0.001) and –0.14 mmHg (95% CI: –0.25– –0.04, P<.01) change in orthostatic diastolic BP recovery, for minimally and fully adjusted models respectively. HR recovery was not significantly associated with BrainPAD.

Conclusion

These results demonstrate that impaired systolic and diastolic BP recovery after standing is associated with accelerated brain aging in older individuals. This suggests that the BP response to standing, measured using beat-to-beat monitoring, has potential to be used as a marker of accelerated brain aging, relying on a simple procedure and devices that are easily accessible for clinical use.

138 ORTHOSTATIC CEREBRAL OXYGENATION AND THE RELATIONSHIP WITH SYMPTOMS, SUPINE HYPERTENSION AND ORTHOSTATIC HYPOTENSION

Background

Cerebral hypoperfusion is implicated as a cause of orthostatic symptoms such as dizziness and light-headedness. In older adults, Orthostatic Hypotension (OH) may co-exist with Supine Hypertension (SH), with greater cerebral dysfunction being reported in those with SH-OH. It remains unclear whether orthostatic symptoms are indicative of a higher cerebral hypotensive burden in older adults. This study assessed cerebral oxygenation in a cohort of older adults experiencing orthostatic symptoms, via an active stand challenge, as well as the relationship with OH and SH.

Methods

We utilized data from Wave 3 of the Irish Longitudinal Study on Ageing (TILDA). Cerebral oxygenation was continuously measured via near infrared-spectroscopy, and blood pressure via a Finometer. Logistic regression was employed to assess cerebral hemodynamics in the sample (N=2,737, mean age=65 years [range: 54-93 years]). Models were adjusted for covariates such as age, sex, standing speed, medications, and cardiovascular conditions.

Results

In the whole sample, 29% of participants reported symptoms, 13% experienced OH30 and 49% had SH. Those who reported symptoms were less likely to have supine hypertension (OR=0.73, p<0.001), but were more likely to experience OH30 (OR=1.69, p=0.005). They were also more likely to experience a larger initial drop in cerebral oxygenation upon standing (β=-0.07%, p=0.006). However, symptoms were not associated with an impaired recovery in cerebral oxygenation at 30 seconds, or 3 minutes after standing.

Conclusion

Supine hypertension is somewhat protective against symptoms, but there is still a relatively large discord between symptoms, cerebral oxygenation and OH during orthostasis. This implies asymptomatic OH may also be a risk factor for adverse outcome. There is a need for routine screening of OH and SH in older adults.

Biodistribution and Tolerability of AAV-PHP.B-CBh-SMN1 in Wistar Han Rats and Cynomolgus Macaques Reveal Different Toxicologic Profiles

Recombinant adeno-associated viruses (AAVs) have emerged as promising vectors for human gene therapy, but some variants have induced severe toxicity in Rhesus monkeys and piglets following high-dose intravenous (IV) administration. To characterize biodistribution, transduction, and toxicity among common preclinical species, an AAV9 neurotropic variant expressing the survival motor neuron 1 (SMN1) transgene (AAV-PHP.B-CBh-SMN1) was administered by IV bolus injection to Wistar Han rats and cynomolgus monkeys at doses of 2 × 10¹³, 5 × 10¹³, or 1 × 10¹⁴ vg/kg. A dose-dependent degeneration/necrosis of neurons without clinical manifestations occurred in dorsal root ganglia (DRGs) and sympathetic thoracic ganglia in rats, while liver injury was not observed in rats. In monkeys, one male at 5 × 10¹³ vg/kg was found dead on day 4. Clinical pathology data on days 3 and/or 4 at all doses suggested liver dysfunction and coagulation disorders, which led to study termination. Histologic evaluation of the liver in monkeys showed hepatocyte degeneration and necrosis without inflammatory cell infiltrates or intravascular thrombi, suggesting that hepatocyte injury is a direct effect of the vector following hepatocyte transduction. In situ hybridization demonstrated a dose-dependent expression of SMN1 transgene mRNA in the cytoplasm and DNA in the nucleus of periportal to panlobular hepatocytes, while quantitative polymerase chain reaction confirmed the dose-dependent presence of SMN1 transgene mRNA and DNA in monkeys. Monkeys produced a much greater amount of transgene mRNA compared with rats. In DRGs, neuronal degeneration/necrosis and accompanying findings were observed in monkeys as early as 4 days after test article administration. The present results show sensory neuron toxicity following IV delivery of AAV vectors at high doses with an early onset in Macaca fascicularis and after 1 month in rats, and suggest adding the autonomic system in the watch list for preclinical and clinical studies. Our data also suggest that the rat may be useful for evaluating the potential DRG toxicity of AAV vectors, while acute hepatic toxicity associated with coagulation disorders appears to be highly species-dependent.

76 PREDICTIVE MODEL FOR MOBILITY DECLINE: INDIVIDUAL TRIAL MISTAKE THRESHOLDS IN SUSTAINED ATTENTION TO RESPONSE TASK (SART)

Background

The Sustained Attention to Response Task (SART) is a standard computer-based cognitive test designed to measure the sustained attention, fundamental for completing tasks that require supervision over time (Robertson et al., 1997). However, commonly used average features may result in loss of information and data misinterpretation, leading to inability to detect clinically expected associations (O’Halloran et al., 2014).

Methods

Here, we present a new method to visualise the full information obtained from the SART test, ordering by age, and categorising in groups based on mobility status in a large population-based study of ageing in Ireland. A new threshold, derived from the visualisation and based on the individual trial number of mistakes, was employed to individuate poorer SART performances, and to predict mobility and cognitive decline after 4 years in binary logistic regression models.

Results

Raw SART data were available for 4,864 participants aged 50 years and over at baseline. The new variable bad performances, expressing the number of SART trials with at least 4 mistakes, was the most significant predictor of mobility decline, defined as the transition from Timed Up-and-Go (TUG) < 12 to TUG ≥12 seconds (Odds Ratio (OR) = 1.29; 95% Confidence Interval (CI) 1.14–1.46; p < 0.001), and the only significant predictor of new falls (OR = 1.11; 95% CI 1.03–1.21; p = 0.011) compared to traditional SART variables in models adjusted for multiple covariates. No SART-related variables resulted significant predictors of cognitive decline, defined as a decrease of at least 2 points in the Mini-Mental State Examination (MMSE) score.

Conclusion

This multimodal visualisation and the new threshold approach could help clinicians to easily develop relevant hypotheses, and better identify subjects at higher risk of future mobility decline.

78 HIGHER NEUROVASCULAR SIGNAL ENTROPY IS ASSOCIATED WITH ACCELERATED BRAIN AGEING

Background

Often chronological age is not the most accurate marker of an individual’s health status since ageing is a heterogeneous process across individuals. Machine learning can be used to quantify the relationship between structural brain MRI data and chronological age, to estimate an individual’s ‘brain age’, which, when subtracted from chronological age, provides a brain predicted-age difference score (BrainPAD) [1]. BrainPAD reflects the biological ageing of the brain. Increased complexity in neurovascular signals has been shown to be associated with poorer cognitive performance and physical frailty [2]. The aim of this study was to investigate associations between the complexity of frontal-lobe oxygenation (tissue saturation index (TSI)) data and BrainPAD in a cohort of older community-dwelling adults.

Methods

To calculate BrainPAD, machine learning was applied to 1,359 T1-weighted MRI brain scans from various open-access repositories, and this model was subsequently applied to MRI data acquired from the study cohort. TSI was non-invasively measured in the left frontal lobe using near-infrared spectroscopy. TSI data were acquired continuously during five minutes of supine rest and the last minute was utilized in this analysis. The complexity of TSI signals was quantified using sample entropy (SampEn). Multivariable linear regression was employed, controlling for age, sex, education, antihypertensive medications, diabetes, cardiovascular conditions, smoking, alcohol, depression, BMI, physical activity, and blood pressure.

Results

Complete data were available for 397 individuals (age: 67.9 ± 7.7 years; 53.7% female). An increase in TSI SampEn of 0.1 was associated with an increase in BrainPAD of 0.9 years (P = 0.007, 95%CIs: 0.3 to 1.6). Similar results were found with and without the inclusion of chronological age in the models.

Conclusion

This study reports significant associations between higher complexity in peripherally measured frontal lobe oxygenation concentration and accelerated brain ageing.

References

1. Boyle R. et al. Brain Imaging and Behavior. 15,327–345 (2021) https://doi.org/10.1007/s11682-020-00260-3.

2. Knight S. et al. Entropy. 23(1):4 (2021) https://doi.org/10.3390/e23010004.

1323Trends in the incidence rates of keratinocyte carcinomas from 1978 to 2018 in Tasmania, Australia

Background

Keratinocyte carcinomas (KCs), namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC), are the most common cancers in Australia. We describe trends in the incidence of KCs in the state of Tasmania over 41 years.

Methods

We identified histologically confirmed KCs within the Tasmanian Cancer Registry. Age-standardised incidence rates were calculated for first (1985-2018) and annual KCs (1978-2018). Average annual percentage changes were computed using Joinpoint regression models.

Results

A total of 83,536 people were registered with a KC between 1978 and 2018. Age-standardised incidence rates of first KCs increased on average by 3% per annum for BCCs and 4% per annum for SCCs, reaching 363/100,000 and 249/100,000 in 2018, respectively. Age-standardised incidence rates of annual KCs increased on average by 5% per annum for BCCs and 6% per annum for SCCs, up to 891/100,000 and 514/100,000 in 2018, respectively. This increase was steeper for females than males and highest during the late 1980s and early 1990s. A change in trend around 2014 suggested that incidence rates have started to decline.

Conclusions

While the incidence of KCs in Tasmania increased substantially since 1978, it has recently plateaued and started to decline. The findings may reflect changes in sun exposure behaviours due to awareness campaigns.

Key messages

Incidence of KCs has increased in 41 years and despite a recent plateau and decline, KCs still pose a substantial burden to the Tasmanian population.

Temporal trends in the incidence rates of keratinocyte carcinomas from 1978 to 2018 in Tasmania, Australia: a population-based study

OBJECTIVES

We described incidence trends of keratinocyte carcinomas (KCs)-namely basal cell carcinoma (BCC) and squamous cell carcinoma (SCC)-in the Australian state of Tasmania.

METHODS

We identified histologically confirmed KCs within the Tasmanian Cancer Registry (TCR) and conducted assessments to ensure data quality. Age-standardised incidence rates were calculated for first (1985-2018) and annual KCs (1978-2018). Average annual percentage changes were computed using Joinpoint regression models.

RESULTS

The TCR is a reliable source of KC data. A total of 83,536 people were registered with a KC between 1978 and 2018. Age-standardised incidence rates of first KCs increased on average by 3% per annum for BCCs and 4% per annum for SCCs, reaching 363/100,000 and 249/100,000 in 2018, respectively. Age-standardised incidence rates of annual KCs increased on average by 5% per annum for BCCs and 6% per annum for SCCs, up to 891/100,000 and 514/100,000 in 2018, respectively. This increase was steeper for females than males and highest during the late 1980s and early 1990s. A change in trend around 2014 suggested that incidence rates have started to decline.

CONCLUSION

While the incidence of KCs in Tasmania increased substantially over 41 years, rates have recently plateaued and started to decline. The findings may reflect changes in sun exposure behaviours due to awareness campaigns, but high incidence rates in 2018 indicate that KCs still pose a substantial burden to this population.

The cross-sectional association between diabetes and orthostatic hypotension in community-dwelling older people

AIMS

Orthostatic hypotension is a recognized complication of diabetes, but studies examining prevalence in diabetes are limited. The aim of this study was to ascertain the prevalence of orthostatic hypotension and the pattern of orthostatic BP response in a cohort of people with diabetes aged ≥ 50 years, embedded within the Irish Longitudinal Study of Ageing.

METHODS

Orthostatic hypotension was defined as a drop in systolic blood pressure (SBP) ≥ 20 mmHg or drop in diastolic blood pressure (DBP) ≥ 10 mmHg at 30 s after standing. Diabetes was defined by self-report but cross-checked against HbA_1c and medication records. Multilevel mixed effects linear regression models were used to compare orthostatic BP in people with and without diabetes.

RESULTS

Some 3222 people were included, 7% (213 of 3222) of whom had diabetes. Prevalence of orthostatic hypotension in the group with diabetes was 22% (46 of 213) vs. 13% in those without diabetes; χ² = 12.43; P < 0.001. Multilevel models demonstrated prolonged recovery of DBP in people with diabetes, with only 41% (87 of 213) returning to baseline by 60 s. Logistic regression models demonstrated that diabetes was associated with a significantly increased likelihood of orthostatic hypotension (odds ratio 1.84, 95% confidence interval 1.30-2.59; P = 0.001) and this remained robust after controlling for covariates.

CONCLUSION

Over one-fifth of older people with diabetes had orthostatic hypotension. Recovery of DBP is related to dynamic changes in total peripheral resistance and impairment of this baroreflex-mediated response may explain the higher prevalence in diabetes. Given the prognostic implications when co-existing with diabetes, orthostatic hypotension may represent a potentially modifiable risk factor for adverse outcomes in late-life diabetes.

Genetic associations with clozapine-induced myocarditis in patients with schizophrenia

Clozapine is the most effective antipsychotic drug for schizophrenia, yet it can cause life-threatening adverse drug reactions, including myocarditis. The aim of this study was to determine whether schizophrenia patients with clozapine-induced myocarditis have a genetic predisposition compared with clozapine-tolerant controls. We measured different types of genetic variation, including genome-wide single-nucleotide polymorphisms (SNPs), coding variants that alter protein expression, and variable forms of human leucocyte antigen (HLA) genes, alongside traditional clinical risk factors in 42 cases and 67 controls. We calculated a polygenic risk score (PRS) based on variation at 96 different genetic sites, to estimate the genetic liability to clozapine-induced myocarditis. Our genome-wide association analysis identified four SNPs suggestive of increased myocarditis risk (P < 1 × 10^-6), with odds ratios ranging 5.5-13.7. The SNP with the lowest P value was rs74675399 (chr19p13.3, P = 1.21 × 10^-7; OR = 6.36), located in the GNA15 gene, previously associated with heart failure. The HLA-C*07:01 allele was identified as potentially predisposing to clozapine-induced myocarditis (OR = 2.89, 95% CI: 1.11-7.53), consistent with a previous report of association of the same allele with clozapine-induced agranulocytosis. Another seven HLA alleles, including HLA-B*07:02 (OR = 0.25, 95% CI: 0.05-1.2) were found to be putatively protective. Long-read DNA sequencing provided increased resolution of HLA typing and validated the HLA associations. The PRS explained 66% of liability (P value = 9.7 × 10^-5). Combining clinical and genetic factors together increased the proportion of variability accounted for (r² 0.73, P = 9.8 × 10^-9). However, due to the limited sample size, individual genetic associations were not statistically significant after correction for multiple testing. We report novel candidate genetic associations with clozapine-induced myocarditis, which may have potential clinical utility, but larger cohorts are required for replication.

A comparison of immunoglobulin IGHV, IGHD and IGHJ genes in wild-derived and classical inbred mouse strains

The genomes of classical inbred mouse strains include genes derived from all three major subspecies of the house mouse, Mus musculus. We recently posited that genetic diversity in the immunoglobulin heavy chain (IGH) gene loci of C57BL/6 and BALB/c mice reflects differences in subspecies origin. To investigate this hypothesis, we conducted high-throughput sequencing of IGH gene rearrangements to document IGH variable (IGHV), joining (IGHJ) and diversity (IGHD) genes in four inbred wild-derived mouse strains (CAST/EiJ, LEWES/EiJ, MSM/MsJ and PWD/PhJ) and a single disease model strain (NOD/ShiLtJ), collectively representing genetic backgrounds of several major mouse subspecies. A total of 341 germline IGHV sequences were inferred in the wild-derived strains, including 247 not curated in the international ImMunoGeneTics information system. By contrast, 83/84 inferred NOD IGHV genes had previously been observed in C57BL/6 mice. Variability among the strains examined was observed for only a single IGHJ gene, involving a description of a novel allele. By contrast, unexpected variation was found in the IGHD gene loci, with four previously unreported IGHD gene sequences being documented. Very few IGHV sequences of C57BL/6 and BALB/c mice were shared with strains representing major subspecies, suggesting that their IGH loci may be complex mosaics of genes of disparate origins. This suggests a similar level of diversity is likely present in the IGH loci of other classical inbred strains. This must now be documented if we are to properly understand interstrain variation in models of antibody-mediated disease.

Creating Models to Identify New Therapeutic Options for Aggressive African Breast Cancers

Background: Population-based incidence rates of breast cancer (BC) that does not express the estrogen receptor (ER), progesterone receptor (PR) or overexpress the human epidermal growth factor 2 HER2/ neu (triple negative breast cancer, TNBC) are higher among Africans compared with white women. However the underlying biologic and genetic differences among different ethnicities are poorly understood and there are currently very few ethnically diverse BC models available for identifying new therapeutic options. Aim: Establish an international collaboration to: i, characterize African breast tumors ii, create models for studying these tumors and iii, identify biomarkers for early detection and treatment personalization. Methods: We have collected tumors from 154 white Americans WA, 76 African Americans, AA, 190 Ethiopians, Eth, and 286 Ghanaian (Gh) BC patients. We then established a unique resource of patient derived xenografts (PDX) from these tumors. The PDXs were then fully characterized using whole exome and RNA sequencing for the primary tumor, matched normal DNA, and corresponding low passage PDXs. Using immunohistochemistry, we evaluated the ER, PR, HER2/ neu, androgen receptor (AR), and ALDH1 (cancer stem cell marker) expression among these tumors. Based on biomarker expression the PDXs were then tested against a panel of IND drugs, either alone or in combinations, in an ex vivo organoid culture system to discover potential new therapeutic options. Results: Mean age at BC diagnosis was 43; 49; 60; and 57 years for the Eth; Gh; AA; and WA patients, respectively. The proportion of TNBC was significantly higher for the AA and Gh patients (41% and 54%, respectively) compared with the WA and Eth patients (23% and 15%, respectively); P < 0.001. Significant differences were observed for distribution of AR positivity, which was 71%; 55%; 42% and 50% for the WA; AA; Gh; and Eth cases, respectively ( P = 0.008). The Gh breast tumors exhibited the highest number of loss of function and missense mutations that are likely to impact therapy with a high frequency of P53, APC, and FGFR mutations. These mutations were maintained in the corresponding PDXs that were developed, and were thus used as biomarkers for drug screening. These tumors exhibited a gene expression signature based on the ethnicity of the patients with 2385 genes differentially expressed between Gh and AA, 1573 between AA and CA and 1317 between GH and CA. Results from our ongoing drug screening and biomarker identification will be available soon. Conclusions: Establishing the molecular and genetic platform of aggressive breast cancers occurring in women with African ancestry will help in identifying biomarkers for early cancer detection and targeted treatment stratification for optimum patient outcome. The availability of tumor models based on tumors from diverse African populations is the important missing pieces that have to be incorporated into current drug discovery efforts.

Single-cell profiling of peanut-responsive T cells in patients with peanut allergy reveals heterogeneous effector TH2 subsets

BACKGROUND

The contribution of phenotypic variation of peanut-specific T cells to clinical allergy or tolerance to peanut is not well understood.

OBJECTIVES

Our objective was to comprehensively phenotype peanut-specific T cells in the peripheral blood of subjects with and without peanut allergy (PA).

METHODS

We obtained samples from patients with PA, including a cohort undergoing baseline peanut challenges for an immunotherapy trial (Consortium of Food Allergy Research [CoFAR] 6). Subjects were confirmed as having PA, or if they passed a 1-g peanut challenge, they were termed high-threshold subjects. Healthy control (HC) subjects were also recruited. Peanut-responsive T cells were identified based on CD154 expression after 6 to 18 hours of stimulation with peanut extract. Cells were analyzed by using flow cytometry and single-cell RNA sequencing.

RESULTS

Patients with PA had tissue- and follicle-homing peanut-responsive CD4+ T cells with a heterogeneous pattern of TH2 differentiation, whereas control subjects had undetectable T-cell responses to peanut. The PA group had a delayed and IL-2-dependent upregulation of CD154 on cells expressing regulatory T (Treg) cell markers, which was absent in HC or high-threshold subjects. Depletion of Treg cells enhanced cytokine production in HC subjects and patients with PA in vitro, but cytokines associated with highly differentiated TH2 cells were more resistant to Treg cell suppression in patients with PA. Analysis of gene expression by means of single-cell RNA sequencing identified T cells with highly correlated expression of IL4, IL5, IL9, IL13, and the IL-25 receptor IL17RB.

CONCLUSIONS

These results demonstrate the presence of highly differentiated TH2 cells producing TH2-associated cytokines with functions beyond IgE class-switching in patients with PA. A multifunctional TH2 response was more evident than a Treg cell deficit among peanut-responsive T cells.

Homologous recombination deficiency and host anti-tumor immunity in triple-negative breast cancer

PURPOSE

Triple-negative breast cancer (TNBC) is associated with worse outcomes relative to other breast cancer subtypes. Chemotherapy remains the standard-of-care systemic therapy for patients with localized or metastatic disease, with few biomarkers to guide benefit.

METHODS

We will discuss recent advances in our understanding of two key biological processes in TNBC, homologous recombination (HR) DNA repair deficiency and host anti-tumor immunity, and their intersection.

RESULTS

Recent advances in our understanding of homologous recombination (HR) deficiency, including FDA approval of PARP inhibitor olaparib for BRCA1 or BRCA2 mutation carriers, and host anti-tumor immunity in TNBC offer potential for new and biomarker-driven approaches to treat TNBC. Assays interrogating HR DNA repair capacity may guide treatment with agents inducing or targeting DNA damage repair. Tumor infiltrating lymphocytes (TILs) are associated with improved prognosis in TNBC and recent efforts to characterize infiltrating immune cell subsets and activate host anti-tumor immunity offer promise, yet challenges remain particularly in tumors lacking pre-existing immune infiltrates. Advances in these fields provide potential biomarkers to stratify patients with TNBC and guide therapy: induction of DNA damage in HR-deficient tumors and activation of existing or recruitment of host anti-tumor immune cells. Importantly, these advances provide an opportunity to guide use of existing therapies and development of novel therapies for TNBC. Efforts to combine therapies that exploit HR deficiency to enhance the activity of immune-directed therapies offer promise.

CONCLUSIONS

HR deficiency remains an important biomarker target and potentially effective adjunct to enhance immunogenicity of 'immune cold' TNBCs.

Abstract P6-07-01: Withdrawn

This abstract was withdrawn by the authors.

Inflammatory pseudotumour of the maxilla

Inflammatory pseudotumour (IP), also known as inflammatory myofibroblastic tumour (IMT), is a rare lesion of the maxillofacial skeleton and a diagnosis by exclusion. We describe three cases which affected the maxilla, two women and one man of ages 67, 56 and 70 years at presentation. All showed the typical, rather non-specific histopathological features. IgG4-positive plasma cells varied greatly in prominence, and none of the three lesions expressed ALK-1. Both women responded to steroids and radiotherapy, though one also required azathioprine. Despite maxillectomy, radiotherapy, steroids and cyclophosphamide, the man suffered intracranial spread and succumbed to persistent disease. The cases described here demonstrate the clinicopathological difficulties presented by this entity and its aggressive, unpredictable behaviour.

Current Concepts in Osteoradionecrosis after Head and Neck Radiotherapy

Osteoradionecrosis (ORN) of the jaws is a feared complication of head and neck radiotherapy. ORN causes significant morbidity for patients and controversy among clinicians. This overview considers the variations in definition and classification of the condition that affect estimates of incidence and also the interpretation of evidence. The influence of newer radiotherapy techniques in reducing ORN through reduced dose and xerostomia is balanced against a probable increase in a vulnerable population through a rising head and neck cancer incidence. Theories of pathophysiology of ORN include radiation-induced osteomyelitis, hypoxic and hypovascular theory and fibroatrophic theory. Prevention strategies include restorative dentistry and radiation planning techniques. Treatments range from conservative 'watch and wait' through to more radical surgical strategies. Newer medical management strategies are available with a limited evidence base. The use of hyperbaric oxygen therapy remains controversial and the background and need for newer hyperbaric oxygen trials is discussed.

Neoplasms in Galagos

Two of 26 adult galagos (Galago crassicaudatus panengiensis) at the California Primate Research Center developed neoplasms. One had a fibrosarcoma of the skin that metastasized to mesenteric lymph nodes. The other had a benign apocrine cystadenoma and lipomas in the skin.

Fractalkine (CX3CL1) and fractalkine receptor (CX3CR1) in squamous cell carcinoma of the tongue: markers of nerve invasion?

PURPOSE

Perineural invasion (PNI) in oral squamous cell carcinoma (SCC) is an independent predictor of poor prognosis. As PNI is not always identified with routine histology, a surrogate marker of PNI would improve detection and better inform treatment planning. The chemokines fractalkine (CX3CL1) and its receptor (CX3CR1) have shown such potential in other cancers, but have yet to be investigated with respect to PNI in oral SCC.

METHODS

Thirty SCCs of the tongue in which PNI was identified histologically, and 30 in which it was not, were stained for fractalkine and fractalkine receptor using polyclonal antibodies and an immunoperoxidase technique. Tumours were assessed as either positive or negative; no attempt was made to subjectively assess staining intensity or extent.

RESULTS

Both markers labelled myofibroblasts in the stroma surrounding the tumour, various neural components, leucocytes, endothelium and salivary myoepithelial cells. Fractalkine also labelled salivary ductal epithelium, vascular smooth muscle and 12/30 SCC which showed PNI. Eight of 30 positive SCCs in which PNI was not identified were also positive for this marker. There was no statistically significant association between fractalkine staining and PNI (p = 0.273). No SCC was positive for fractalkine receptor, but immune dendritic cells within tumour islands were strongly positive, as was striated muscle.

CONCLUSIONS

Neither fractalkine nor fractalkine receptor is a reliable surrogate marker of PNI in lingual SCC.

Biodegradation of Polychlorinated Dibenzo--Dioxins by Strain NSYSU

The dioxin-degrading bacterium strain NSYSU (NSYSU strain) has been isolated from dioxin-contaminated soil by selective enrichment techniques. In the present study, the NSYSU strain was investigated for its capability to biodegrade polychlorinated dibenzo--dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) under aerobic and anaerobic conditions. High-resolution gas chromatography-mass spectrometry and a chemically activated luciferase gene expression bioassay were performed to determine the presence of dioxin compounds. The results indicate that the NSYSU strain could degrade PCDDs and PCDFs under anaerobic conditions in liquid cultures. The main intermediates of the dechlorination process were identified. The results of the bioreactor test indicate that the NSYSU strain could also degrade PCDDs and PCDFs effectively in soil slurries under aerobic conditions. Results from the bioreactor experiment show that approximately 98 and 97% of octachlorodibenzofuran and OCDD were degraded, respectively. The dioxin concentrations in soil slurry decreased from 5823 to 1198 pg toxic equivalency g, resulting in total dioxin removal of 79%. These first findings suggest that the NSYSU strain has the potential to be an effective tool for the bioremediation of soils contaminated with highly recalcitrant organic compounds.

'I could never do that before': effectiveness of a tailored Internet support intervention to increase the social participation of youth with disabilities

BACKGROUND

Youth use the Internet for a variety of purposes including social networking. Youth with disabilities are limited in their social networks and friendships with peers. The aim was to investigate the effectiveness of tailored one-on-one support strategies designed to facilitate social participation of youth with disabilities through the use of the Internet for social networking.

METHODS

Eighteen youth aged 10-18 years with cerebral palsy, physical disability or acquired brain injury received support, training and assistive technology at their home to learn to use the Internet for building social networks. The Canadian Occupational Performance Measure (COPM) and Goal Attainment Scale (GAS) were used to evaluate objective changes in performance and satisfaction. Interviews with the youth identified subjective changes they experienced through participation in the programme and to determine whether and how the intervention influenced their social participation.

RESULTS

Youth showed an increase in performance and satisfaction with performance on identified goals concerning social networking on the COPM; Paired T-test showed that these differences were statistically significant at P < 0.001. GAS T-scores demonstrated successful outcomes (>50) for 78% of the youth. Interviews showed that youth were positive about the benefits of hands-on training at home leading to increased use of the Internet for social networking.

CONCLUSIONS

The Internet could be a viable method to facilitate social participation for youth with disabilities. Youth identified the benefits of one-to-one support at home and training of the family compared with typical group training at school. Despite its success with this group of youth, the time and effort intensive nature of this approach may limit the viability of such programmes. Further longitudinal research should investigate whether Internet use is sustained post intervention, and to identify the factors that best support ongoing successful and safe use.