Tetramer Stability Research Articles

RNA Interference Therapeutics for Hereditary Amyloidosis: A Narrative Review of Clinical Trial Outcomes and Future Directions.

Hereditary transthyretin amyloidosis (ATTR) is an autosomal dominant, life-threatening genetic disorder caused by a single-nucleotide variant in the transthyretin gene. This mutation leads to the misfolding and deposition of amyloid in various body organs. Both mutant and wild-type transthyretin contribute to the resulting polyneuropathy and cardiomyopathy, leading to significant sensorimotor disturbances and severe cardiac conditions such as heart failure and arrhythmias, thereby impacting quality of life. Despite several treatments, including orthotopic liver transplantation and transthyretin tetramer stabilizers, their limitations persisted until the introduction of RNA interference (RNAi). RNAi, a means to regulate mRNA stability and translation of targeted genes, has brought about significant changes in treatment strategies for ATTR with the introduction of patisiran in 2018. This study reviews patisiran, vutrisiran, inotersen, and eplontersen, developed for the treatment of ATTR. It provides an overview of the clinical trial outcomes, focusing mainly on quality of life, adverse reactions, and the future of RNAi-based therapies.

A Comprehensive Review on Chemistry and Biology of Tafamidis in Transthyretin Amyloidosis.

Transthyretin amyloid cardiomyopathy and Transthyretin amyloid peripheral neuropathy are progressive disease conditions caused by Transthyretin amyloidosis (ATTR) fibril infiltration in the tissue. Transthyretin (TTR) protein misfolding and amyloid fibril deposits are pathological biomarkers of ATTR-related disorders. There are various treatment strategies targeting different stages in pathophysiology. One such strategy is TTR tetramer stabilization. Recently, a new TTR tetramer stabilizer, tafamidis, has been introduced that reduces the protein misfolding and amyloidosis and, consequently, disease progression in ATTR cardiomyopathy and peripheral neuropathy. This review will provide a comprehensive overview of the literature on tafamidis discovery, development, synthetic methods, pharmacokinetics, analytical methods and clinical trials. Overall, 7 synthetic methods, 5 analytical methods and 23 clinical trials have been summarized from the literature.

Synthesis and PET Imaging Biodistribution Studies of Radiolabeled Iododiflunisal, a Transthyretin Tetramer Stabilizer, Candidate Drug for Alzheimer's Disease.

The small-molecule iododiflunisal (IDIF) is a transthyretin (TTR) tetramer stabilizer and acts as a chaperone of the TTR-Amyloid beta interaction. Oral administration of IDIF improves Alzheimer's Disease (AD)-like pathology in mice, although the mechanism of action and pharmacokinetics remain unknown. Radiolabeling IDIF with positron or gamma emitters may aid in the in vivo evaluation of IDIF using non-invasive nuclear imaging techniques. In this work, we report an isotopic exchange reaction to obtain IDIF radiolabeled with 18F. [19F/18F]exchange reaction over IDIF in dimethyl sulfoxide at 160 °C resulted in the formation of [18F]IDIF in 7 ± 3% radiochemical yield in a 20 min reaction time, with a final radiochemical purity of >99%. Biodistribution studies after intravenous administration of [18F]IDIF in wild-type mice using positron emission tomography (PET) imaging showed capacity to cross the blood-brain barrier (ca. 1% of injected dose per gram of tissue in the brain at t > 10 min post administration), rapid accumulation in the liver, long circulation time, and progressive elimination via urine. Our results open opportunities for future studies in larger animal species or human subjects.

LncRNA PWRN1 inhibits the progression of hepatocellular carcinoma by activating PKM2 activity

Hepatocellular carcinoma (HCC) is one of the most prevalent and leading causes of cancer-related mortality worldwide. Long non-coding RNAs (lncRNAs) have been demonstrated to play vital roles in cancer development and progression. The lncRNA PWRN1 (PWRN1), acts as a tumor suppressor factor, which is low expressed in some cancers. However, the molecular mechanisms underlying the effects of PWRN1, especially the regulatory relationship with RNA binding protein in HCC remain largely unknown. In the present study, we demonstrated that PWRN1 was significantly down-regulated in HCC and correlated with better prognosis; furthermore, gain-of-function experiments showed that PWRN1 inhibited the proliferation of HCC cells. We further found that PWRN1 up-regulated pyruvate kinase activity and thus hinders the proliferation of HCC in vitro and in vivo. Mechanistically, pyruvate kinase M2 (PKM2) was bound to it and maintained the high activity state of PKM2, thereby hindering PKM2 from entering the nucleus in the form of low-activity dimers, reducing the expression of c-Myc downstream gene LDHA, leading to a decrease in lactate levels, and inhibiting the growth of tumor cells. In addition, PWRN1 was found to inhibit aerobic glycolysis. Finally, TEPP-46, a pyruvate kinase activator, appeared to inhibit HCC proliferation by maintaining tetramer stability and increasing pyruvate kinase activity. Taken together, our results provide new insights into the biology hindering HCC proliferation and indicate that PWRN1 in combination with PKM2 activators might represent a novel therapeutic target for HCC.

Tafamidis improves myocardial longitudinal strain in A97S transthyretin cardiac amyloidosis.

Transthyretin cardiomyopathy (ATTR-CM) is a debilitating disease that has received much attention since the emergence of novel treatments. The Transthyretin Cardiomyopathy Clinical Trial showed that tafamidis, a transthyretin tetramer stabilizer, effectively reduced the declines in functional capacity and quality of life. However, Ala97Ser (A97S) hereditary ATTR-CM is underrepresented in major ATTR-CM tafamidis trials. We aim to investigate the change in global longitudinal strain (GLS) of A97S ATTR-CM patients after 12 months of tafamidis treatment. We retrospectively analysed a prospective cohort of patients with A97S ATTR-CM who received tafamidis meglumine (61 mg/day) at the National Taiwan University Hospital. Echocardiography with speckle tracking strain analysis was performed at baseline and 12 months after treatment. In all, 20 patients were included in the cohort. The baseline left ventricular ejection fraction (LVEF) and interventricular septum (IVS) thickness were 59.20 ± 13.23% and 15.10 ± 3.43 mm, respectively. After 12 months of tafamidis treatment, the LVEF and IVS were 61.83 ± 15.60% (p = 0.244) and 14.59 ± 3.03 mm (p = 0.623), respectively. GLS significantly improved from -12.70 ± 3.31% to -13.72 ± 3.17% (p = 0.048), and longitudinal strain (LS) in apical and middle segments significantly improved from -16.05 ± 4.82% to -17.95 ± 3.48% (p = 0.039) and -11.89 ± 4.38% to -13.58 ± 3.12% (p = 0.039), respectively. Subgroup analysis showed that patients with LVEF < 50% had a better treatment response and improvement in GLS. The patients with an IVS ⩾ 13 mm had an improvement in two-chamber LS from -10.92 ± 4.25% to -13.15 ± 3.87% (p = 0.042) and an improvement in apical left ventricular LS from -15.30 ± 5.35% to -17.82 ± 3.99% (p = 0.031). Tafamidis significantly improved GLS, and particularly apical and middle LS in A97S ATTR-CM patients.

Abstract 18049: Mathematical Modeling Predicts Treatment Efficacy in Transthyretin Cardiac Amyloidosis

Introduction: Increased recognition of transthyretin cardiac amyloidosis (ATTR-CA) led to the development of treatments with different therapeutic targets. Optimal patient selection, treatment choice, timing and duration remain unclear. We evaluated the efficacy and timing of common and emerging ATTR-CA treatments with a mathematical model based on therapeutic mechanisms. Methods: We developed a system of ordinary differential equations describing transthyretin amyloid (ATTR) deposition and myocardial clearance by clusterin (Figure 1A,B). Published data and equilibrium analyses determined parameters for initial maximal ATTR density. Mechanisms of four therapies were modeled and simulated at varying levels of efficacy. Complete success of the mechanism defines 100% efficacy, i.e. full stabilization of tetramer. Expected clinical efficacy (ECE) is based on studies of clinical doses. Minimum effective clearance (MEC) is the theoretical efficacy required to reduce ATTR fibrils below the threshold for complete clearance. Results: All treatments reduced ATTR fibril density, correlating with efficacy (Fig 1C). At ECE, only NI006 demonstrated complete clearance of ATTR fibrils. With other current treatment strategies, amyloid density will be lowered but never cleared. The secondary mechanism of diflusinil did not change equilibrium behavior compared to tafamidis. MEC values and time to clearance at MEC were lowest for NI006 (14.7%; 65 days) and doxycycline (16.1%; 36 months). Tetramer stabilization required almost complete efficacy (99.3%) and about a decade (119 months) for tetramer clearance. Conclusion: This mathematical model predicts ATTR clearance by four distinct mechanisms of action. The novel anti-ATTR antibody NI006 is a promising treatment with predicted faster onset and higher effectiveness for clearance of ATTR fibrils from the myocardium. This model can evaluate future treatment strategies and therapeutic targets.

Neurological manifestations of ATTR amyloidosis

Transthyretin amyloidosis (ATTR) is arare disease in which the protein transthyretin (TTR) is deposited in the form of amyloid fibrils in various tissues and organs and secondarily leads to functional impairment, especially in peripheral nerves and the heart. A differentiation is made between hereditary and sporadic forms. The hereditary variant is inherited in an autosomal dominant manner and usually occurs in the younger to middle-aged, while the sporadic form occurs in older age and has no known genetic cause. Typical signs of hereditary ATTR amyloidosis (ATTRv, v for variant) include a rapidly progressing sensorimotor and autonomic polyneuropathy (PNP), cardiac dysfunction as well as ocular and gastrointestinal symptoms. A carpal tunnel syndrome often precedes the manifestation. Various options (tafamidis, patisiran, inotersen or vutrisiran) are available for the treatment of patients with ATTRv with PNP in Germany, depending on the severity. In the sporadic variant of wild-type ATTR amyloidosis (ATTRwt), symptoms of progressive cardiomyopathy are usually prominent; however, neurological assessment of these patients often also reveals aconcomitant sensory ataxic PNP. The tetramer stabilizer tafamidis can be used for treatment. Because of this complex presentation, the management of patients with ATTR amyloidosis should be performed in interdisciplinary centers specialized in amyloidosis.

Thermodynamic stability of cytosine tetramers mediated by partially reduced silver trimers: QM/MM free energy analysis

AbstractPartially reduced silver clusters growing in a polycytosine matrix could simultaneously possess stabilizing ability and remarkable optical features. The mechanisms of this phenomenon are not fully understood so far. We examined the thermodynamic stability of a cytosine–silver associate comprising four cytosines and three silver atoms that can be considered the smallest known luminescent silver marker stabilized on DNA. Quantum and molecular mechanical representations thermodynamic integration toward the dissociation pathway of the cytosine tetramer, time‐dependent density functional theory calculations of the lowest energy excited states and quantum theory of atoms in molecules analysis of bonding showed that the reduction of two ions within the silver trimer mediating cytosine tetramer leads to the appearance of the green‐emitting silver cluster with low stabilization ability of cytosines relative to a tetramer stabilized by two silver ions.

Elucidation of novel TRAP1-Selective inhibitors that regulate mitochondrial processes

Hsp90 isoform-selective inhibitors represent a new paradigm for novel anti-cancer drugs as each of the four isoforms have specific cellular localization, function, and client proteins. The mitochondrial isoform, TRAP1, is the least understood member of the Hsp90 family due to the lack of small molecule tools to study its biological function. Herein, we report novel TRAP1-selective inhibitors used to interrogate TRAP1's biological function along with co-crystal structures of such compounds bound to the N-terminus of TRAP1. Solution of the co-crystal structure allowed for a structure-based approach that resulted in compound 36, which is a 40 nM inhibitor with >250-fold TRAP1 selectivity over Grp94, the isoform with the highest structural similarity to TRAP1 within the N-terminal ATP binding site. Lead compounds 35 and 36 were found to selectively induce TRAP1 client protein degradation without inducing the heat shock response or disrupting Hsp90-cytosolic clients. They were also shown to inhibit OXPHOS, alter cellular metabolism towards glycolysis, disrupt TRAP1 tetramer stability, and disrupt the mitochondrial membrane potential.

Attenuation of reverse transcriptase facilitates SAMHD1 restriction of HIV-1 in cycling cells

BackgroundSAMHD1 is a deoxynucleotide triphosphohydrolase that restricts replication of HIV-1 in differentiated leucocytes. HIV-1 is not restricted in cycling cells and it has been proposed that this is due to phosphorylation of SAMHD1 at T592 in these cells inactivating the enzymatic activity. To distinguish between theories for how SAMHD1 restricts HIV-1 in differentiated but not cycling cells, we analysed the effects of substitutions at T592 on restriction and dNTP levels in both cycling and differentiated cells as well as tetramer stability and enzymatic activity in vitro.ResultsWe first showed that HIV-1 restriction was not due to SAMHD1 nuclease activity. We then characterised a panel of SAMHD1 T592 mutants and divided them into three classes. We found that a subset of mutants lost their ability to restrict HIV-1 in differentiated cells which generally corresponded with a decrease in triphosphohydrolase activity and/or tetramer stability in vitro. Interestingly, no T592 mutants were able to restrict WT HIV-1 in cycling cells, despite not being regulated by phosphorylation and retaining their ability to hydrolyse dNTPs. Lowering dNTP levels by addition of hydroxyurea did not give rise to restriction. Compellingly however, HIV-1 RT mutants with reduced affinity for dNTPs were significantly restricted by wild-type and T592 mutant SAMHD1 in both cycling U937 cells and Jurkat T-cells. Restriction correlated with reverse transcription levels.ConclusionsAltogether, we found that the amino acid at residue 592 has a strong effect on tetramer formation and, although this is not a simple “on/off” switch, this does correlate with the ability of SAMHD1 to restrict HIV-1 replication in differentiated cells. However, preventing phosphorylation of SAMHD1 and/or lowering dNTP levels by adding hydroxyurea was not enough to restore restriction in cycling cells. Nonetheless, lowering the affinity of HIV-1 RT for dNTPs, showed that restriction is mediated by dNTP levels and we were able to observe for the first time that SAMHD1 is active and capable of inhibiting HIV-1 replication in cycling cells, if the affinity of RT for dNTPs is reduced. This suggests that the very high affinity of HIV-1 RT for dNTPs prevents HIV-1 restriction by SAMHD1 in cycling cells.

Therapeutic Strategies for Hereditary Transthyretin Amyloidosis

Disease-modifying therapies such as transthyretin (TTR) gene-silencing drugs and TTR tetramer stabilizers have been developed for hereditary transthyretin (ATTR) amyloidosis, a major type of autosomal dominant hereditary amyloidosis. Recently, a second-generation TTR gene-silencing drug, vutrisiran, was approved for treating patients with hereditary ATTR amyloidosis in Japan. This new drug significantly reduced the patient's physical burden.

Microwave-Assisted Extraction Optimization and Effect of Drying Temperature on Catechins, Procyanidins and Theobromine in Cocoa Beans.

Cocoa beans (Theobroma cacao L.) are an important source of polyphenols. Nevertheless, the content of these compounds is influenced by post-harvest processes. In this sense, the concentration of polyphenols can decrease by more than 50% during drying. In this study, the process of procyanidins extraction was optimized and the stability of catechins, procyanidins, and theobromine to different drying temperatures was evaluated. First, the effectiveness of methanol, ethanol, acetone, and water as extract solvents was determined. A Box-Behnken design and response surface methodology were used to optimize the Microwave-Assisted Extraction (MAE) process. The ratios of methanol-water, time, and temperature of extraction were selected as independent variables, whereas the concentration of procyanidins was used as a response variable. Concerning the drying, the samples were dried using five temperatures, and a sample freeze-dried was used as a control. The quantitative analyses were carried out by HPLC-DAD-ESI-IT-MS. The optimal MAE conditions were 67 °C, 56 min, and 73% methanol. Regarding the drying, the maximum contents of procyanidins were obtained at 40 °C. To our knowledge, this is the first time that the stability of dimers, trimers, and tetramers of procyanidins on drying temperature was evaluated. In conclusion, drying at 40 °C presented better results than the freeze-drying method.

Treatment of amyloidosis: present and future.

Cardiac amyloidosis (CA) is an infiltrative heart disease resulting from the deposition of amyloid fibrils in the interstitial spaces of the myocardium. The two main forms of CA are represented by light chain amyloidosis (AL) and transthyretin amyloidosis (ATTR) in the two forms familial or variant or wild-type or senile. Although considered a rare disease, CA is an underdiagnosed disease. Delay in diagnosis has a negative impact on the prognosis, delaying the initiation of specific therapy. The treatment of both forms of CA is based on: (i) prevention and slowing of the generation and deposition of amyloid fibrils and (ii) supportive care of complications. The main success of recent years has been the development of effective therapies that have been possible thanks to the understanding of the pathophysiology of amyloidosis. For the AL form, new therapeutic combinations between a proteasome inhibitor and a monoclonal antibody have been developed. For ATTR forms, the main strategies are transthyretin (TTR) production 'silencers' and TTR tetramer stabilizers. Supportive care of patients with CA involves various clinical aspects including treatment of heart failure, arrhythmias, conduction disturbances, thrombo-embolism, and the concomitant presence of aortic stenosis.

Emerging Therapies for Transthyretin Amyloidosis

This review provides an overview of the available therapies for treating neuropathic and/or cardiac manifestations of transthyretin amyloidosis (ATTR), as well as investigational therapeutic agents in ongoing clinical trials. We discuss additional emergent approaches towards thwarting this life-threatening disease that until recently was considered virtually untreatable. Advances in noninvasive diagnostic methods for detecting ATTR have facilitated easier diagnosis and detection at an earlier stage of disease when therapeutic interventions are likely to be more effective. There are now several ATTR-directed treatments that are clinically available, as well as investigational agents that are being studied in clinical trials. Therapeutic strategies include tetramer stabilization, gene silencing, and fibril disruption. ATTR has been historically underdiagnosed. With advances in diagnostic methods and the advent of disease-modifying treatments, early diagnosis and initiation of treatment is revolutionizing management of this disease.

Lack of STAT1 co-operative DNA binding protects against adverse cardiac remodelling in acute myocardial infarction.

In this study, we addressed the functional significance of co-operative DNA binding of the cytokine-driven transcription factor STAT1 (signal transducer and activator of transcription 1) in an experimental murine model of acute myocardial infarction (MI). STAT1 knock-in mice expressing a phenylalanine-to-alanine substitution at position 77 in the STAT1 amino-terminal domain were examined for the early clinical effects produced by ligation of the left anterior descending coronary artery (LAD), an established model for MI. The F77A mutation has been previously reported to disrupt amino-terminal interactions between adjacent STAT1 dimers resulting in impaired tetramerization and defective co-operative binding on DNA, while leaving other protein functions unaffected. Our results demonstrate that a loss of STAT1 tetramer stabilization improves survival of adult male mice and ameliorates left ventricular dysfunction in female mice, as determined echocardiographically by an increased ejection fraction and a reduced left intra-ventricular diameter. We found that the ratio of STAT3 to STAT1 protein level was higher in the infarcted tissue in knock-in mice as compared to wild-type (WT) mice, which was accompanied by an enhanced infiltration of immune cells in the infarcted area, as determined by histology. Additionally, RNA sequencing of the infarcted tissue 24 h after LAD ligation revealed an upregulation of inflammatory genes in the knock-in mice, as compared to their WT littermates. Concomitantly, genes involved in oxidative phosphorylation and other metabolic pathways showed a significantly more pronounced downregulation in the infarcted tissue from STAT1F77A/F77A mice than in WT animals. Based on these results, we propose that dysfunctional STAT1 signalling owing to a lack of oligomerisation results in a compensatory increase in STAT3 expression and promotes early infiltration of immune cells in the infarcted area, which has beneficial effects on left ventricular remodelling in early MI following LAD ligation.

Omega-3 PUFAs as a Dietary Supplement in Senile Systemic Amyloidosis.

Eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6), two omega-3 poly-unsaturated fatty acids (PUFAs), are the main components in oil derived from fish and other marine organisms. EPA and DHA are commercially available as dietary supplements and are considered to be very safe and contribute to guaranteeing human health. Studies report that PUFAs have a role in contrasting neurodegenerative processes related to amyloidogenic proteins, such as β-amyloid for AD, α-synuclein in PD, and transthyretin (TTR) in TTR amyloidosis. In this context, we investigated if EPA and DHA can interact directly with TTR, binding inside the thyroxin-binding pockets (T4BP) that contribute to the tetramer stabilization. The data obtained showed that EPA and DHA can contribute to stabilizing the TTR tetramer through interactions with T4BP.

ANMCO Position paper: Amyloidosis for the clinical cardiologist. A "clinical primer" from the ANMCO Rare Disease Working Group

Cardiac amyloidosis, in the three forms of immunoglobulin light chain (AL), transthyretin (ATTR) wild type (ATTRwt) and mutated (ATTRv) amyloidosis, is an increasingly known and recognized disease in the cardiovascular setting. The first stage of the patient's journey is the clinical suspicion of the disease, which is placed, in presence of a hypertrophic phenotype, by the identification of red flags, both extracardiac and cardiac clues whose presence increase the probability of being faced with a patient with this disease. The second stage is represented by diagnosis, which occurs with certainty through the identification of amyloid substance in cardiac tissue. This stage is spotted in wo parts, i.e. disease confirmation and disease etiology definition (AL vs ATTRwt vs ATTRv). However, it is possible in some selected cases to make a diagnosis of ATTR without the need for tissue assessment, in presence of a positive grade 2-3 bisphosphonate scintigraphy and absence of monoclonal component. Once the diagnosis has been made, the third stage is the assessment of prognosis, the fourth is the patient therapy pathway and fifth is the follow-up plan. Prognosis evaluation is based on different staging systems at the onset of the disease, whose applicability in the era of new effective therapies is still to be defined. To date, the transthyretin tetramer stabilizer tafamidis is the only approved treatment for both wild-type and mutant ATTR cardiomyopathy without polyneuropathy, while ATTRv with associated neuropathy can benefit from treatment with patisiran, an inhibitor of hepatic protein synthesis. Therapies for complications and comorbidities, must be addressed individually, due to the lack of specific clinical trials on this category of patients. In fact, it is important to take into consideration the risks linked to the use of some drugs due to the infiltration of the conduction tissue by the amyloid substance, which increases the risk of bradycardia and heart blocks, the tendency towards hypotension and the increased thromboembolic risk. It is also essential to follow the course of the disease and the efficacy of the treatment in affected patients with a standardized follow-up, and to identify early the signs/symptoms of the disease in asymptomatic TTR mutation carriers.This ANMCO position paper on amyloidosis aims to provide the clinical cardiologist with a practical summary of the disease, to accompany the patient with amyloidosis in the various stages of his journey.

Oxidative dehydrogenation of cyclohexene on atomically precise subnanometer Cu4-nPdn (0 ≤ n ≤ 4) tetramer clusters: the effect of cluster composition and support on performance.

The pronounced effects of the composition of four-atom monometallic Cu and Pd and bimetallic CuPd clusters and the support on the catalytic activity and selectivity in the oxidative dehydrogenation of cyclohexene are reported. The ultra-nanocrystalline diamond supported clusters are highly active and dominantly produce benzene; some of the mixed clusters also produce cyclohexadiene, which are all clusters with a much suppressed combustion channel. The also highly active TiO2-supported tetramers solely produce benzene, without any combustion to CO2. The selectivity of the zirconia-supported mixed CuPd clusters and the monometallic Cu cluster is entirely different; though they are less active in comparison to clusters with other supports, these clusters produce significant fractions of cyclohexadiene, with their selectivity towards cyclohexadiene gradually increasing with the increasing number of copper atoms in the cluster, reaching about 50% for Cu3Pd1. The zirconia-supported copper tetramer stands out from among all the other tetramers in this reaction, with a selectivity towards cyclohexadiene of 70%, which far exceeds those of all the other cluster-support combinations. The findings from this study indicate a positive effect of copper on the stability of the mixed tetramers and potential new ways of fine-tuning catalyst performance by controlling the composition of the active site and via cluster-support interactions in complex oxidative reactions under the suppression of the undesired combustion of the feed.

Abstract 14613: Amyloidosis-Related Orthopedic Events, Low Plasma Transthyretin, and Risk of Cardiac Events

Introduction: Carpal tunnel syndrome, spinal stenosis, and biceps tendon rupture may precede cardiac transthyretin amyloidosis (ATTR-CA). Hypothesis: We tested the hypothesis that amyloidosis-related orthopedic events herald amyloidosis and cardiac events consistent with ATTR-CA through transthyretin destabilization. Methods: In observational analysis in the Copenhagen General Population Study (CGPS; n=93,637), we first tested whether amyloidosis-related orthopedic events at baseline were associated with amyloidosis and incident cardiac events consistent with ATTR-CA (heart failure, atrial fibrillation, myocardial infarction, or death), and whether a low plasma transthyretin was associated with a higher risk. In genetic analysis, in CGPS and the Copenhagen City Heart Study(CCHS) combined (n=102,496), we tested whether TTR genotypes associated with stepwise lower plasma transthyretin, marking lower transthyretin tetramer stability and higher amyloidogenic potential, was associated with both orthopedic and incident cardiac events, implying a common mechanistic background through transthyretin destabilization. Results: In individuals with versus without orthopedic events at baseline, hazard ratios (HRs) were 10.7 (95% CI: 3.9-29.3) for amyloidosis, and 1.3(1.1-1.4) for cardiac events. Furthermore, in individuals with orthopedic events at baseline, HRs for cardiac events were 3.8(1.9-7.6) in those with transthyretin &lt;20 mg/dL versus ≥20 mg/dL (Figure 1). Finally, HRs as a function of TTR genotype increased with lower transthyretin and lower transthyretin tetramer stability up to 3.0(1.4-6.6) for orthopedic events and 1.6(95% CI: 1.0-2.6) for cardiac events. Conclusion: Amyloidosis-related orthopedic events are associated with increased risk of incident cardiac events, with the highest risk in those with low transthyretin levels. Orthopedic and cardiac events are linked through transthyretin tetramer destabilization.

Development of a Highly Potent Transthyretin Amyloidogenesis Inhibitor: Design, Synthesis, and Evaluation.

Transthyretin amyloidosis (ATTR) is a group of fatal diseases described by the misfolding and amyloid deposition of transthyretin (TTR). Discovering small molecules that bind and stabilize the TTR tetramer, preventing its dissociation and subsequent aggregation, is a therapeutic strategy for these pathologies. Departing from the crystal structure of TTR in complex with tolcapone, a potent binder in clinical trials for ATTR, we combined rational design and molecular dynamics (MD) simulations to generate a series of novel halogenated kinetic stabilizers. Among them, M-23 displays one of the highest affinities for TTR described so far. The TTR/M-23 crystal structure confirmed the formation of unprecedented protein-ligand contacts, as predicted by MD simulations, leading to an enhanced tetramer stability both in vitro and in whole serum. We demonstrate that MD-assisted design of TTR ligands constitutes a new avenue for discovering molecules that, like M-23, hold the potential to become highly potent drugs to treat ATTR.