Modelling rheumatic heart disease progression in australia using disease register data linked to administrative records

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Australian Government National Health and Medical Research Council

OnBehalf

ERASE project

Background

Rheumatic Heart Disease (RHD) is a major contributor to morbidity and mortality globally, and is endemic among Indigenous Australians. The RHD Endgame strategy was recently launched, outlining comprehensive methods for eliminating RHD in Australia by 2031. However, there is currently limited information on national rates of RHD and progression to severe or complicated RHD.

Purpose

This study provides current estimates of RHD progression prior to RHD Endgame Strategy implementation. We estimate the probability and predictors of progressing from RHD diagnosis to cardiovascular complications, death, or need for surgical intervention in the Australian population from expanded data sources, addressing methodological shortcomings in existing evidence by using cross-jurisdictional administrative datasets and a competing risks approach.

Methods

This retrospective cohort study used linked RHD register, hospital and death data from five Australian jurisdictions (>70% Australians). Progression from RHD diagnosis to all-cause mortality, non-fatal cardiovascular complications (heart failure, stroke, endocarditis, atrial fibrillation), or need for surgical intervention were estimated for people aged <35years diagnosed with first-ever RHD between 2010 and 2018. A minimum 8.5-year look-back excluded prevalent cases; maximum follow-up was 8 years. Proportional cause-specific hazard regression modelling investigated independent predictors of outcomes, with death treated as a competing risk.  Sensitivity analyses compared results between all-sources and register-only cohorts.

Results

We identified 1714 first-ever RHD cases aged <35years in the all-sources cohort (84% Indigenous, 11% migrant, 63% women, 40% age 5-14years, 85% non-metropolitan). Six months after diagnosis, 8.1% (95%CI:6.9-9.5%) had experienced heart failure, other cardiovascular complications or surgical intervention and 23.6% (95%CI:20.2-27.5%) progressed to these outcomes within 8 years. The register-only cohort experienced less disease progression with estimated composite event rates of 5.6% (95%CI:4.7-6.6%) and 18.4% (95%CI:16.6-20.5%) at 6 month and 8 years respectively. Death rate in the all-sources cohort was 0.5% at 6 months and 3.2% at 8 years. Older age, Metropolitan residence, and history of acute rheumatic fever, but not sex or Indigenous status, were independent predictors of major cardiovascular outcomes.

Conclusions

This study provides the most definitive and contemporary estimates of RHD disease progression in young Australians. Despite Australia"s excellent healthcare system infrastructure, RHD complication rates remain high.  Improvements in healthcare systems for diagnosis, monitoring, and management of RHD cases will need to be implemented in both Metropolitan and remote settings as Australia implements its Endgame strategy against RHD. However, primordial and primary prevention provides the best potential to reduce the burden of RHD in Australia and beyond.

Abstract P5-04-06: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Katzenellenbogen JA, Min J, Kim SH, Laws MJ, Zhao Y, Ziegler Y, Nelson ER, Shahoei SH, Chu D, Park BH, Katzenellenbogen BS. 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 P5-04-06.

Abstract P5-04-11: Non-canonical, clinical ESR1 mutations promote resistance to antiestrogen therapies

ESR1 hotspot mutations have been identified in 30-40% of patients with ER+ MBC and promote resistance to aromatase inhibitors (AIs). Identification of these mutations has been aided by the use of plasma DNA for their detection, however many such tests only survey for hotspot mutations. In this study, we examined the prevalence, biologic and clinical significance of mutations in ESR1 that lie outside previously described hotspots (E380Q, Y537, D538G). Using next generation sequencing of tumor DNA from over 4000 patients with breast cancer, we have identified numerous somatic alterations in ESR1. Among the somatic alterations were mutations detected in the transcription activation function-1 (AF-1), DNA binding domain, dimerization interface and C-terminus of ER.

We characterized the functional significance of these non-canonical mutations alongside hotspot mutations, starting with assays of ER driven transcription and deduced several classes of mutations: (1) mutations that weakly promote ligand-independent activity, (2) mutations that led to ligand-independent activity comparable to estradiol stimulation, and (3) mutations that resulted in impaired transcriptional activity. Class 2 mutations remain localized at amino acids 536-538, while the class 1 mutations are observed in various domains of ESR1, including the DNA binding domain and dimerization interface. Several Class 3 mutations were found in proximal to Helix 12, highlighting the critical role of this region.

Clinically, non-canonical mutations were not exclusively observed among patients treated with AI, as there were several mutations from SERM/SERD treated patients. We thus examined the effects of different mutants on their sensitivity to ER antagonists, such as fulvestrant or tamoxifen. The data revealed key differences between the different classes of mutants; with majority of the class 2 mutants exhibiting reduced sensitivity to the antagonists compared to wild type. This also correlated with the relative binding affinities (RBA) of the mutants to fulvestrant and 4-hydroxytamoxifen, in which the RBA of class 2 mutants (Y537S and D538G) were significantly lower than wild type, perhaps accounting for their reduced sensitivities. Nevertheless, it appeared that all mutants could be effectively inhibited either by higher concentrations or more potent ER antagonists, implying a continued ability to distort ER into the antagonist conformation. Interestingly, several Class 1 mutants showed weak agonism in response to specific antagonists raising the possibility of their role in SERM/SERD resistance. Taken together, the data demonstrated that not all ESR1 mutations affect receptor function or respond to antiestrogen therapies similarly. These data also imply the importance of more broad sequencing coverage of ESR1 in the clinic to effectively capture the spectrum of biologically relevant alleles.

Citation Format: Toy W, Carlson KE, Martin TA, Razavi P, Berger M, Baselga J, Greene G, Katzenellenbogen J, Chandarlapaty S. Non-canonical, clinical ESR1 mutations promote resistance to antiestrogen therapies [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 P5-04-11.

Abstract P4-07-02: Withdrawn

This abstract was withdrawn by the authors.

Citation Format: Katzenellenbogen BS, Guillen VS, Ziegler Y, Kim SH, Laws MJ, Zhao Y, Yasuda MA, Li Z, El-Ashry D, Katzenellenbogen JA. 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 P4-07-02.

Abstract P2-08-07: Anti-proliferative and anti-inflammatory estrogen receptor agents for treatment of endocrine-resistant breast cancer

This abstract was not presented at the symposium.

Extra-nuclear effects of estrogen on cortical bone in males require ERαAF-1

Estradiol (E2) signaling via estrogen receptor alpha (ERα) is important for the male skeleton as demonstrated by ERα inactivation in both mice and man. ERα mediates estrogenic effects not only by translocating to the nucleus and affecting gene transcription but also by extra-nuclear actions e.g., triggering cytoplasmic signaling cascades. ERα contains various domains, and the role of activation function 1 (ERαAF-1) is known to be tissue specific. The aim of this study was to determine the importance of extra-nuclear estrogen effects for the skeleton in males and to determine the role of ERαAF-1 for mediating these effects. Five-month-old male wild-type (WT) and ERαAF-1-inactivated (ERαAF-1⁰) mice were orchidectomized and treated with equimolar doses of 17β-estradiol (E2) or an estrogen dendrimer conjugate (EDC), which is incapable of entering the nucleus and thereby only initiates extra-nuclear ER actions or their corresponding vehicles for 3.5 weeks. As expected, E2 treatment increased cortical thickness and trabecular bone volume per total volume (BV/TV) in WT males. EDC treatment increased cortical thickness in WT males, whereas no effect was detected in trabecular bone. In ERαAF-1⁰ males, E2 treatment increased cortical thickness, but did not affect trabecular bone. Interestingly, the effect of EDC on cortical bone was abolished in ERαAF-1⁰ mice. In conclusion, extra-nuclear estrogen signaling affects cortical bone mass in males, and this effect is dependent on a functional ERαAF-1. Increased knowledge regarding estrogen signaling mechanisms in the regulation of the male skeleton may aid the development of new treatment options for male osteoporosis.

Abstract P3-05-07: RAD1901, a novel oral, selective estrogen receptor degrader (SERD) with single agent efficacy in an ER+ primary patent derived ESR1 mutant xenograft model

Despite advances in the treatment of metastatic breast cancer, many women eventually relapse with more aggressive forms of endocrine-resistant disease. Mutations in the ESR1 gene encoding the estrogen receptor (ER) have recently emerged as a potential mechanism for the development of clinical resistance to conventional anti-estrogen therapies, such as fulvestrant. To overcome some of the pharmacokinetic limitations and intramuscular administration challenges associated with fulvestrant endocrine therapy and to combat the development of resistance, there is a significant need for the development of more durable and more effective ER-targeted therapies. Here, we begin to describe and characterize the preclinical efficacy of RAD1901, a novel, orally bioavailable small-molecule SERD, with significant therapeutic potential for treatment of breast cancer. RAD1901 selectively binds to and degrades the ER and is a potent antagonist of ER-positive breast cancer cell proliferation. Importantly, RAD1901 demonstrated profound tumor growth inhibition in MCF-7 xenograft models when compared to fulvestrant and tamoxifen. Importantly, RAD1901 also demonstrated marked single agent efficacy in a primary patient-derived xenograft (PDx) model harboring the ESR1 Y537S mutation indicating the utility of this SERD against clinically relevant ER mutants. Further biochemical binding studies and co-crystallization experiments of RAD1901 bound to the ER further confirms the ability of RAD1901 to bind to both mutant and wild type forms of the ER. RAD1901 is currently undergoing clinical testing in postmenopausal women with ER-positive advanced breast cancer.

Citation Format: Garner F, Brown J, Katzenellenbogen J, Lyttle CR, Hattersley G. RAD1901, a novel oral, selective estrogen receptor degrader (SERD) with single agent efficacy in an ER+ primary patent derived ESR1 mutant xenograft model. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P3-05-07.

ESR1 and ESR2 differentially regulate daily and circadian activity rhythms in female mice

Estrogenic signaling shapes and modifies daily and circadian rhythms, the disruption of which has been implicated in psychiatric, neurologic, cardiovascular, and metabolic disease, among others. However, the activational mechanisms contributing to these effects remain poorly characterized. To determine the activational impact of estrogen on daily behavior patterns and differentiate between the contributions of the estrogen receptors ESR1 and ESR2, ovariectomized adult female mice were administered estradiol, the ESR1 agonist propylpyrazole triol, the ESR2 agonist diarylpropionitrile, or cholesterol (control). Animals were singly housed with running wheels in a 12-hour light, 12-hour dark cycle or total darkness. Estradiol increased total activity and amplitude, consolidated activity to the dark phase, delayed the time of peak activity (acrophase of wheel running), advanced the time of activity onset, and shortened the free running period (τ), but did not alter the duration of activity (α). Importantly, activation of ESR1 or ESR2 differentially impacted daily and circadian rhythms. ESR1 stimulation increased total wheel running and amplitude and reduced the proportion of activity in the light vs the dark. Conversely, ESR2 activation modified the distribution of activity across the day, delayed acrophase of wheel running, and advanced the time of activity onset. Interestingly, τ was shortened by estradiol or either estrogen receptor agonist. Finally, estradiol-treated animals administered a light pulse in the early subjective night, but no other time, had an attenuated response compared with controls. This decreased phase response was mirrored by animals treated with diarylpropionitrile, but not propylpyrazole triol. To conclude, estradiol has strong activational effects on the temporal patterning and expression of daily and circadian behavior, and these effects are due to distinct mechanisms elicited by ESR1 and ESR2 activation.

The effects of the phytoestrogen, coumestrol, on gonadotropin-releasing hormone (GnRH) mRNA expression in GT1-7 GnRH neurones

Phytoestrogens can produce inhibitory effects on gonadotropin secretion in both animals and humans, although little is known about the mechanisms and the role of direct action on oestrogen receptors (ER) in this process. We examined the effect of coumestrol, alone and combined with ER antagonists, on gonadotropin-releasing hormone (GnRH) mRNA expression in GT1-7 cells. Coumestrol was found to have an inhibitory effect compared to controls, which was blocked by R,R-THC, a selective ER beta antagonist. These results suggest that ER beta is involved in the suppression of GnRH mRNA expression by coumestrol.

Hospital utilisation expectancies in New Zealand, 1980-98

The need to synthesise mortality and morbidity information to achieve a more global and relevant measure of population health status is well recognised, with health expectancy indices being the most common approach used to date. Using New Zealand hospital discharge and mortality data over the 1980-98 period, we introduce readers to a newly developed health index, the Hospital Utilisation Expectancy (HUE). We describe how HUE changes with age and over time. New Zealand national and regional trends are described. The methodological strengths of the measure and its applications in the health sector are discussed.

Fluorine-substituted ligands for the peroxisome proliferator-activated receptor gamma (PPARgamma): potential imaging agents for metastatic tumors

The peroxisome proliferator-activated receptor gamma (PPARgamma), a primary regulator of lipid metabolism, is present in many tumor cell lines and animal tumor systems and, in some cases, can mediate effective antitumor therapy with potent synthetic ligands. In an approach to image tumors with positron-emission tomography (PET) based on their content of PPARgamma, we have synthesized two fluorine-substituted analogues of a high affinity ligand from the phenylpropanoic acid class. The analogue having the highest affinity for PPARgamma was labeled with the positron-emitting radionuclide fluorine-18. In tissue distribution studies in normal rats and in SCID mice bearing human breast tumor xenografts, this compound did not show evidence of receptor-mediated uptake. The prospects for using PPARgamma as a target for imaging tumors may be limited by the low receptor concentrations in tumors and by the pharmacokinetic behavior of this class of ligands, which appears to be more favorable for therapy than for imaging.

Structure-function relationships in estrogen receptors and the characterization of novel selective estrogen receptor modulators with unique pharmacological profiles

This article summarizes recent research on the development of estrogen receptor alpha (ER alpha) and estrogen receptor beta (ER beta) subtype-selective ligands based on our understanding of structure-activity relationships in these two estrogen receptors and differences in their ligand binding domains and activation function domains. The use of these ligands should enable greater understanding of the unique biologies mediated by ER alpha versus ER beta and may, as well, provide selective estrogen receptor modulators having unique biological and pharmacological profiles optimal for prevention and treatment of breast cancer, for menopausal hormone replacement, for prevention of osteoporosis, and for potential cardiovascular benefit.