[Incidence and causes of hospitalization in patients with transthyretin (ATTR-CA) and light chain (AL-CA) cardiac amyloidosis]

INTRODUCTION AND OBJETIVES

Cardiac amyloidosis (CA) is a disorder associated with high number of hospital admissions. Given the scarce information available, we propose an analysis of the incidence and causes of hospitalization in this disease.

MATERIAL AND METHODS

One hundred and forty-three patients [128 by transthyretin (ATTR-CA) and 15 by light chains (AL-CA)] included in Registro de Amiloidosis Cardiaca de Galicia (AMIGAL) were evaluated, including all hospitalizations.

RESULTS

During a median follow-up of 959 days there were 179 unscheduled hospitalizations [incidence rate (IR) 512.6 admissions per 1000 patients-year], most common due to cardiovascular reasons (n=109, IR 312.2). Most frequent individual cause of hospitalization was heart failure (n=87, TI 249.2). AL-CA was associated with a higher IR of unscheduled hospitalizations than ATTR-CA (IR 781 vs. 483.2; HR 1.62; p=0,029) due to non-cardiovascular admissions (IR 376 vs. 181.2; HR 2.07; p=0.027). Unscheduled admission-free survival at 1 and 3 years in AL-CA was inferior than in ATTR-CA (46.7% and 20.0% vs. 73.4% and 35.2%, respectively; p=0.021).

CONCLUSIONS

CA was associated with high incidence of hospitalizations, being heart failure the most frequent individual cause; unscheduled admission-free survival in AL-CA was lower than in ATTR-CA due mostly to non-cardiovascular admissions.

Early detection of nerve involvement in presymptomatic TTR mutation carriers: exploring potential markers of disease onset

BACKGROUND

Hereditary transthyretin (ATTRv) amyloidosis is a heterogeneous, progressive, multisystemic disease with a life-threatening course if left untreated. Given the current availability of effective therapies, close follow-up of presymptomatic TTR mutation carriers is essential to recognize disease onset at the earliest sign. In addition to routine techniques, in recent years several novel tools have been proposed, although a consensus on their use has not been reached yet. In this paper, we aimed to evaluate possible markers of neuropathic disease onset intended to discriminate clinically asymptomatic carriers from early symptomatic patients, thus allowing timely treatment initiation.

METHODS

Thirty-eight presymptomatic carriers were enrolled. Clinical and electrophysiological findings at first evaluation and follow-up were collected. All carriers underwent an extensive clinical and instrumental evaluation according to the standard clinical practice. One or more non-routine investigations, whose use in this field is not yet validated (henceforth "unconventional"), were additionally assessed in a subgroup of individuals.

RESULTS

Based on the exclusive use of routine investigations, it was possible to define disease onset in 4/38 carriers during the follow-up. Employing additionally one or more "unconventional" tests, abnormal findings, indicative of a possible "conversion" to symptomatic disease, were detected in further 12 cases. More than half of our study cohort showed findings suggestive of small nerve fiber (SF) involvement at either invasive or non-invasive tests.

CONCLUSIONS

A close, multidisciplinary monitoring of presymptomatic TTR mutation carriers is fundamental, and diagnostic workup should include both routine and "unconventional" tests. Assessment of SF involvement is important also in non-endemic countries.

Patient-reported outcome measures for transthyretin cardiac amyloidosis: the ITALY study

BACKGROUND

Transthyretin cardiac amyloidosis (ATTR-CA) has a deep impact on the quality of life (QoL), yet no specific patient-reported outcome measures (PROMs) for ATTR-CA exist.

METHODS

The ITALY study involved 5 Italian referral centres (Pisa, Pavia, Ferrara, Florence, Messina) enrolling consecutive outpatients with ATTR-CA.

RESULTS

Two 30-item questionnaires were created for wild-type (wt) and variant (v) ATTR-CA. Scores ranged from 100 (best condition) to 0 (worst condition). Out of 140 patients enrolled (77% with ATTRwt-CA), 115 repeated the re-evaluation at 6 months. At baseline, only 30% of patients needed help to fill out the questionnaires. Among baseline variables, all KCCQ and SF-36 domains were univariate predictors of ITALY scores in ATTRwt-CA patients, with the KCCQ Symptom Summary score (beta coefficient 0.759), Social Limitations (0.781), and Overall summary score (0.786) being the strongest predictors. The SF-36 Emotional well-being score (0.608), the KCCQ Overall summary score (0.656), and the SF-36 Energy/fatigue score (0.669) were the strongest univariate predictors of ITALY scores in ATTRv-CA. Similar results were found at 6 months.

CONCLUSIONS

The ITALY questionnaires are the first specific PROMs for ATTRwt- and ATTRv-CA. Questionnaire completion is feasible. ITALY scores display close relationships with non-ATTR-specific measures of QoL.

Historic characteristics and mortality of patients in the Swiss Amyloidosis Registry

AIMS OF THE STUDY

Systemic amyloidoses are rare protein-folding diseases with heterogeneous, often nonspecific clinical presentations. To better understand systemic amyloidoses and to apply state-of-the-art diagnostic pathways and treatment, the interdisciplinary Amyloidosis Network was founded in 2013 at University Hospital Zurich. In this respect, a registry was implemented to study the characteristics and life expectancy of patients with amyloidosis within the area covered by the network. Patient data were collected retrospectively for the period 2005-2014 and prospectively from 2015 onwards.

METHODS

Patients aged 18 years or older diagnosed with any subtype of systemic amyloidosis were eligible for inclusion if they were treated in one of the four referring centres (Zurich, Chur, St Gallen, Bellinzona). Baseline data were captured at the time of diagnosis. Follow-up data were assessed half-yearly for the first two years, then annually.

RESULTS

Between January 2005 and March 2020, 247 patients were screened, and 155 patients with confirmed systemic amyloidosis were included in the present analysis. The most common amyloidosis type was light-chain (49.7%, n = 77), followed by transthyretin amyloidosis (40%, n = 62) and amyloid A amyloidosis (5.2%, n = 8). Most patients (61.9%, n = 96) presented with multiorgan involvement. Nevertheless, single organ involvement was seen in all types of amyloidosis, most commonly in amyloid A amyloidosis (75%, n = 6). The median observation time of the surviving patients was calculated by the reverse Kaplan-Meier method and was 3.29 years (95% confidence interval [CI] 2.33-4.87); it was 4.87 years (95% CI 3.14-7.22) in light-chain amyloidosis patients and 1.85 years (95% CI 1.48-3.66) in transthyretin amyloidosis patients, respectively. The 1-, 3- and 5-year survival rates were 87.0% (95% CI 79.4-95.3%), 68.5% (95% CI 57.4-81.7%) and 66.0% (95% CI 54.6-79.9%) respectively for light-chain amyloidosis patients and 91.2% (95% CI 83.2-99.8%), 77.0% (95% CI 63.4-93.7%) and 50.6% (95% CI 31.8-80.3%) respectively for transthyretin amyloidosis patients. There was no significant difference between the two groups (p = 0.81).

CONCLUSION

During registry set-up, a more comprehensive work-up of our patients suffering mainly from light-chain amyloidosis and transthyretin amyloidosis was implemented. Survival rates were remarkably high and similar between light-chain amyloidosis and transthyretin amyloidosis, a finding which was noted in similar historic registries of international centres. However, further studies are needed to depict morbidity and mortality as the amyloidosis landscape is changing rapidly.

Current and Evolving Multimodality Cardiac Imaging in Managing Transthyretin Amyloid Cardiomyopathy

Amyloid transthyretin (ATTR) amyloidosis is a protein-misfolding disease characterized by fibril accumulation in the extracellular space that can result in local tissue disruption and organ dysfunction. Cardiac involvement drives morbidity and mortality, and the heart is the major organ affected by ATTR amyloidosis. Multimodality cardiac imaging (ie, echocardiography, scintigraphy, and cardiac magnetic resonance) allows accurate diagnosis of ATTR cardiomyopathy (ATTR-CM), and this is of particular importance because ATTR-targeting therapies have become available and probably exert their greatest benefit at earlier disease stages. Apart from establishing the diagnosis, multimodality cardiac imaging may help to better understand pathogenesis, predict prognosis, and monitor treatment response. The aim of this review is to give an update on contemporary and evolving cardiac imaging methods and their role in diagnosing and managing ATTR-CM. Further, an outlook is presented on how artificial intelligence in cardiac imaging may improve future clinical decision making and patient management in the setting of ATTR-CM.

Silencing of ocular transthyretin, a gene responsible for hereditary transthyretin amyloidosis, by intravitreal injection of an siRNA conjugate into rabbit eyes

The first small interfering RNA (siRNA) therapeutic received approval for hereditary transthyretin (ATTRv) amyloidosis, and the patients' lifespan extension by specific inhibition of hepatic synthesis of transthyretin (TTR) is expected. However, ocular amyloidosis in these patients has been a crucial issue. This study aims to evaluate the efficacy and safety of intravitreal TTR siRNA conjugate injection into rabbit eyes. Rabbit (r) TTR siRNA is a screened TTR siRNA conjugate from 53 candidates. The intraocular pressure (IOP) immediately after injection was high despite the 65.9 % decrease of aqueous humor TTR protein levels in the rTTR siRNA group compared with those in the Control siRNA group 2 weeks after the 50 μL siRNA injection. The IOP spike was milder after the 30 μL siRNA injection, and aqueous humor TTR levels decreased by ∼50 % in the rTTR siRNA group, which is consistent with the mRNA levels in the retina. The parameters of dark-adapted, light-adapted, and light-adapted 30 Hz electroretinogram and the thickness of each retinal layer in histological analysis demonstrated no significant differences between the groups. In conclusion, we developed TTR siRNA conjugates for rabbit eyes, and the results indicate that intravitreal TTR siRNA conjugate injection could be a therapeutic option for ocular amyloidosis caused by ATTRv amyloidosis.

Exploring Transthyretin Amyloid Cardiomyopathy: A Comprehensive Review of the Disease and Upcoming Treatments

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a mutation-based genetic disorder due to the accumulation of unstable transthyretin protein and presents with symptoms of congestive heart failure (CHF) and numerous extracardiac symptoms like carpal tunnel syndrome and neuropathy. Two subtypes of ATTR-CM are hereditary and wild-type, both of which have different risk factors, gender prevalence and major clinical symptoms. Timely usage of imaging modalities like echocardiography, cardiac magnetic imaging resonance, and cardiac scintigraphy has made it possible to suspect ATTR-CM in patients presenting with CHF. Management of ATTR-CM includes appropriate treatment for heart failure for symptomatic relief, prevention of arrhythmias and heart transplantation for nonresponders. With the recent approval of tafamidis in the successful management of ATTR-CM, numerous potential therapeutic points have been identified to stop or delay the progression of ATTR-CM. This article aims to provide a comprehensive review of ATTR-CM and insights into its novel therapeutics and upcoming treatments.

Advances in the diagnosis and treatment of transthyretin amyloid cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underrecognized cause of heart failure (HF). ATTR-CM can lead to a number of cardiovascular manifestations including HF, rhythm disturbances, and valvular disease that ultimately limit quality of life and prognosis. Due to advances in diagnostic modalities and therapeutic options, the prevalence of ATTR-CM is rising. There are several classes of medications under active investigation, though most therapies are most efficacious if instituted early on in the disease course. As such, early clinical recognition and prompt diagnosis are crucial to improving disease related outcomes. In this review, we highlight clinical manifestations of ATTR-CM as well as contemporary diagnostic and treatment approaches to the disease.

RNA Interference and Neuromuscular Diseases: A Focus on Hereditary Transthyretin Amyloidosis

Neuromuscular diseases are severe disorders affecting the peripheral nervous system, usually driving to death in a limited time. Many new drugs, through RNA-interference technology, are revolutionizing the prognosis and quality of life for these patients. Nevertheless, given the increased life expectancy, some new issues and phenotypes are expected to be revealed. In the transthyretin-mediated hereditary amyloidosis (ATTR-v, "v" for "variant"), the RNA interference was demonstrated to effectively reduce the hepatic synthesis of transthyretin, with a significant increase in disease progression in terms of polyneuropathy and cardiomyopathy. The increased life expectancy could promote the involvement of organs where the extra-hepatic transthyretin is deposited, such as the brain and eye, which are probably not targeted by the available treatments. All these issues are discussed in this editorial.

Predictors and outcomes of pacemaker implantation in patients with cardiac amyloidosis

OBJECTIVE

We sought to investigate prevalence, incidence and prognostic implications of permanent pacemaker (PPM) implantation in patients with cardiac amyloidosis (CA), thereby identifying the predictors of time to PPM implantation.

METHODS

Seven hundred eighty-seven patients with CA (602 men, median age 74 years, 571 transthyretin amyloidosis (ATTR), 216 light-chain amyloidosis (AL)) evaluated at two European referral centres were retrospectively included. Clinical, laboratory and instrumental data were analysed. The associations between PPM implantation and mortality, heart failure (HF) or a composite endpoint of mortality, cardiac transplantation and HF were analysed.

RESULTS

81 (10.3%) patients had a PPM before initial evaluation. Over a median follow-up time of 21.7 months (IQR 9.6-45.2), 81 (10.3%) additional patients (18 with AL (22.2%) and 63 with ATTR (77.8%)) underwent PPM implantation with a median time to implantation of 15.6 months (IQR 4.2-40), complete atrioventricular block was the most common indication (49.4%). Independent predictors of PPM implantation were QRS duration (HR 1.03, 95% CI 1.02 to 1.03, p<0.001) and interventricular septum (IVS) thickness (HR 1.1, 95% CI 1.03 to 1.17, p=0.003). The model to estimate the probability of PPM at 12 months and containing both factors showed a C-statistic of 0.71 and a calibration of slope of 0.98.

CONCLUSIONS

Conduction system disease requiring PPM is a common complication in CA that affects up to 20.6% of patients. QRS duration and IVS thickness are independently associated with PPM implantation. A PPM implantation at 12 months model was devised and validated to identify patients with CA at higher risk of requiring a PPM and who require closer follow-up.

Health care resource use, diagnostic delay and disease burden in transthyretin amyloid cardiomyopathy in Sweden

AIMS

To estimate healthcare resource use and direct healthcare costs of Transthyretin Amyloid Cardiomyopathy (ATTR-CM) in Sweden over 12 months across severity stages as defined by the New York Heart Association (NYHA). Secondary to investigate the current diagnostic trajectory for patients with ATTR-CM in Sweden.

METHODS

A stratified inclusion of patients with a confirmed diagnosis of ATTR-CM in different NYHA classes. Data was extracted from medical records in two cardiology clinics in Sweden. Healthcare resource use data were retrospectively collected for 12 months.

RESULTS

38 patients were included, of whom 7 were in NYHA class II, 20 in class III and 4 in class IV. The total cost of health care per patient increased from SEK 69,000 (€6800) in NYHA stage II, SEK 219,000 (€21,500) in NYHA stage III, to SEK 638,000 (€62,900) in stage IV, mainly due to an increase in inpatient stays. Mean time (standard deviation, SD) from any cardiac related diagnosis prior to ATTR-CM diagnosis was 3.5 (3.1) years.

CONCLUSIONS

Advanced ATTR-CM stages are associated with significant healthcare costs, as patients more often require resource-intensive inpatient care. The current diagnostic trajectory of ATTR-CM in this study was characterized by a diagnostic delay of several years.

Occupational practice in patients with hereditary transthyretin amyloidosis, a qualitative study

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRv) is a rare genetic disease that negatively affects patients' quality of life through the involvement of various organs and tissues. Despite a large amount of research on medical and psychosocial interventions, the impact of occupational therapy (OT) on patients with ATTRv is not well understood.

OBJECTIVE

The aim of this study was to develop an OT programme to improve the daily functioning and quality of life of patients with ATTRv.

METHODS

Fourteen patients with ATTRv were interviewed. Together they developed short- and medium-term occupational goals. Patients received the OT intervention for six months. Outcomes were measured using scores for activities of daily living and psychological well-being.

RESULTS

The study found that OT can have a positive impact as a complementary intervention to medical and other psychosocial treatments. Of the 14 patients, 12 maintained the same scores in activities of daily living. Two deteriorated and eight improved their psychological scores.

CONCLUSION

This study highlights the need for further research in this area and the importance of OT in the management of patients with ATTRv. Early intervention is of paramount importance and further research is needed to evaluate the long-term effects of OT interventions in patients with ATTRv.

Hereditary transthyretin amyloidosis in the era of RNA interference, antisense oligonucleotide, and CRISPR-Cas9 treatments

Hereditary transthyretin amyloidosis (ATTRv) is a rare autosomal dominant adult-onset disorder caused by point mutations in the transthyretin (TTR) gene encoding TTR, also known as prealbumin. ATTRv survival ranges from 3 to 10 years, and peripheral nervous system and heart are usually the 2 main tissues affected, although central nervous system and eye may also be involved. Because the liver is the main TTR protein secretor organ, it has been the main target of treatments developed these last years, including liver transplantation, which has been shown to significantly increase survival in a subset of patients carrying the so-called "early-onset Val30Met" TTR gene mutation. More recently, treatments targeting hepatic TTR RNA have been developed. Hepatic TTR RNA targeting is performed using RNA interference (RNAi) and antisense oligonucleotide (ASO) technologies involving lipid nanoparticle carriers or N-acetylgalactosamine fragments. RNAi and ASO treatments induce an 80% decrease in TTR liver production for a period of 1 to 12 weeks. ASO and RNAi phase 3 trials in patients with TTR-related polyneuropathy have shown a positive impact on neuropathy clinical scores and quality of life end points, and delayed RNAi treatment negatively affects survival. Clinical trials specifically investigating RNAi therapy in TTR cardiomyopathy are underway. Hepatic RNA targeting has revolutionized ATTRv treatment and may allow for the transforming a fatal disease into a treatable disorder. Because retina and choroid plexus secrete limited quantities of TTR protein, both tissues are now seen as the next targets for fully controlling the disease.

Hereditary transthyretin amyloid neuropathies: advances in pathophysiology, biomarkers, and treatment

Hereditary transthyretin (TTR) amyloid polyneuropathy is an autosomal dominant life-threatening disorder. TTR is produced mainly by the liver but also by the choroid plexus and retinal pigment epithelium. Detailed clinical characterisation, identification of clinical red flags for misdiagnosis, and use of biomarkers enable early diagnosis and treatment. In addition to liver transplantation and TTR stabilisers, three other disease-modifying therapies have regulatory approval: one antisense oligonucleotide (inotersen) and two small interfering RNAs (siRNAs; patisiran and vutrisiran). The siRNAs have been shown to stop progression of neuropathy and improve patients' quality of life. As none of the disease-modifying therapies can cross the blood-brain barrier, TTR deposition in the CNS, which can cause stroke and cognitive impairment, remains an important unaddressed issue. CRISPR-Cas9-based one-time TTR editing therapy is being investigated in a phase 1 clinical study. Identification of the earliest stages of pathogenesis in TTR variant carriers is a major challenge that needs addressing for optimal management.

World Heart Federation Consensus on Transthyretin Amyloidosis Cardiomyopathy (ATTR-CM)

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive and fatal condition that requires early diagnosis, management, and specific treatment. The availability of new disease-modifying therapies has made successful treatment a reality. Transthyretin amyloid cardiomyopathy can be either age-related (wild-type form) or caused by mutations in the TTR gene (genetic, hereditary forms). It is a systemic disease, and while the genetic forms may exhibit a variety of symptoms, a predominant cardiac phenotype is often present. This document aims to provide an overview of ATTR-CM amyloidosis focusing on cardiac involvement, which is the most critical factor for prognosis. It will discuss the available tools for early diagnosis and patient management, given that specific treatments are more effective in the early stages of the disease, and will highlight the importance of a multidisciplinary approach and of specialized amyloidosis centres. To accomplish these goals, the World Heart Federation assembled a panel of 18 expert clinicians specialized in TTR amyloidosis from 13 countries, along with a representative from the Amyloidosis Alliance, a patient advocacy group. This document is based on a review of published literature, expert opinions, registries data, patients' perspectives, treatment options, and ongoing developments, as well as the progress made possible via the existence of centres of excellence. From the patients' perspective, increasing disease awareness is crucial to achieving an early and accurate diagnosis. Patients also seek to receive care at specialized amyloidosis centres and be fully informed about their treatment and prognosis.

Severe chronic diarrhoea caused by hereditary transthyretin amyloidosis

Amyloidosis includes a heterogeneous group of diseases caused by the extracellular deposition of insoluble fibrillar proteins, leading to multiple organ dysfunction and a poor life expectancy. In the early stages of amyloidosis, gastrointestinal (GI) symptoms are uncommon. We describe a rare case of hereditary transthyretin amyloidosis (ATTRv) with involvement of the heart, nervous system and GI tract. A man in his 60s was hospitalised due to chronic diarrhoea, orthostatic hypotension, malabsorption and weight loss. An organic origin for the diarrhoea was suspected, but the most common causes were ruled out. The review of GI biopsies and an abdominal fat aspirate confirmed the diagnosis of amyloidosis. The diagnosis of ATTRv amyloidosis with GI presentation is challenging, especially in the early stages, and misdiagnosis is common. The recent approval of therapies emphasises the importance of early diagnosis to prevent irreversible organ damage.

Optimal practices for the management of hereditary transthyretin amyloidosis: real-world experience from Japan, Brazil, and Portugal

Hereditary transthyretin (ATTRv) amyloidosis is a rare and autosomal dominant disorder associated with mutations in the transthyretin gene. Patients present with diverse symptoms related to sensory, motor, and autonomic neuropathy, as well as gastrointestinal, ocular, cardiac, renal and orthopedic symptoms, resulting from the deposition of transthyretin amyloid fibrils in multiple organs. The progressive nature of ATTRv amyloidosis necessitates pre- and post-onset monitoring of the disease. This review article is primarily based on a collation of discussions from a medical advisory board meeting in August 2021. In this article, we summarize the best practices in amyloidosis centers in three major endemic countries for ATTRv amyloidosis (Japan, Brazil, and Portugal), where most patients carry the Val30Met mutation in the transthyretin gene and the patients' genetic background was proven to be the same. The discussions highlighted the similarities and differences in the management of asymptomatic gene mutation carriers among the three countries in terms of the use of noninvasive tests and tissue biopsies and timing of starting the investigations. In addition, this article discusses a set of practical tests and examinations for monitoring disease progression applicable to neurologists working in diverse medical settings and generalizable in non-endemic countries and areas. This set of assessments consists of periodic (every 6 to 12 months) evaluations of patients' nutritional status and autonomic, renal, cardiac, ophthalmologic, and neurological functions. Physical examinations and patient-reported outcome assessments should be also scheduled every 6 to 12 months. Programs for monitoring gene mutation carriers and robust referral networks can aid in appropriate patient management in pre- to post-onset stages. For pre- and post-symptom onset testing for ATTRv amyloidosis, various noninvasive techniques are available; however, their applicability differs depending on the medical setting in each country and region, and the optimal option should be selected in view of the clinical settings, medical environment, and available healthcare resources in each region.

Diagnosis and treatment of transthyretin amyloidosis cardiomyopathy: A position statement of the Polish Cardiac Society

Considering the rare incidence of transthyretin amyloidosis cardiomyopathy (ATTR-CM) in Poland, patients encounter difficulties at the stages of diagnosis and treatment. For successful diagnosis, it is vital to raise the suspicion of ATTR-CM, that is, to identify typical clinical scenarios such as heart failure with preserved ejection fraction or the red flags of amyloidosis. In most cases, it is possible to establish the diagnosis on the basis of noninvasive tests. This article presents the recommended diagnostic algorithms including laboratory workup, imaging tests (in particular, isotope scanning), and genetic tests. Since ATTR-CM should be differentiated from light chain amyloidosis, we also discuss aspects related to hematological manifestations and invasive diagnosis. We describe neurological signs and symptoms in patients with amyloidosis and present therapeutic options, including the causative treatment of ATTR-CM with the only currently approved drug, tafamidis. We also discuss drugs that are being assessed in ongoing clinical trials. We outline differences in the symptomatic treatment of heart failure in ATTR-CM and recommendations for nonpharmacological treatment and monitoring of the disease. Finally, we underline the need for providing access to the causative treatment with tafamidis as part of a drug program, as in other rare diseases, so that patients with ATTR-CM can be treated according to the European Society of Cardiology guidelines on heart failure and cardiomyopathy.

The patient pathway in ATTR-CM in Greece and how to improve it: A multidisciplinary perspective

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underdiagnosed disease associated with high mortality rates and the patient journey is characterized by increased complexities. Accurate and timely diagnosis and prompt initiation of disease-modifying treatment constitute the contemporary unmet need in ATTR-CM. ATTR-CM diagnosis is characterized by considerable delays and high rates of misdiagnosis. The majority of patients present themselves to primary care physicians, internists, and cardiologists, and many have undergone repeated medical evaluations before an accurate diagnosis has been made. The disease is diagnosed mainly after the development of heart failure symptoms, reflecting a long course of missed opportunities before diagnosis and disease-modifying treatment initiation. Early referral to experienced centers ensures prompt diagnosis and therapy. Early diagnosis, better care coordination, acceleration of digital transformation and reference networks, encouragement of patient engagement, and implementation of rare disease registries are the key pillars to improve the ATTR-CM patient pathway and achieve important benefits in ATTR-CM outcomes.

A Comprehensive Multidisciplinary Diagnostic Algorithm for the Early and Efficient Detection of Amyloidosis

Amyloidosis is a rare protein misfolding disease caused by the accumulation of amyloid fibrils in various tissues and organs. There are different subtypes of amyloidosis, with light chain (AL) amyloidosis being the most common. Amyloidosis is notoriously difficult to diagnose because it is clinically heterogeneous, no single test is diagnostic for the disease, and diagnosis typically involves multiple specialists. Here, we propose an integrated, multidisciplinary algorithm for efficiently diagnosing amyloidosis. Drawing on research from several medical disciplines, we have combined clinical decisions and best practices into a comprehensive algorithm to facilitate the early detection of amyloidosis. Currently, many patients are diagnosed more than 6 months after symptom onset, yet early diagnosis is the major predictor of survival. Our algorithm aims to shorten the time to diagnosis with efficient sequencing of tests and minimizing uninformative investigations. We also recommend typing and staging of confirmed amyloidosis to guide treatment. By reducing time to diagnosis, our algorithm could lead to earlier and more targeted treatment, ultimately improving prognosis and survival.

Drug and Gene Therapy for Treating Variant Transthyretin Amyloidosis (ATTRv) Neuropathy

Variant Transthyretin Amyloidosis (ATTRv) neuropathy is an adult-onset, autosomal dominant, lethal, multisystemic disease due to the deposition of mutated transthyretin (TTR) in various organs, commonly involving the peripheral nerves and the heart. Circulating TTR tetramers are unstable due to the presence of mutated TTR and dissociate into monomers, which misfold and form amyloid fibrils. Although there are more than 140 mutations in the TTR gene, the p.Val50Met mutation is by far the commonest. In the typical, early-onset cases, it presents with a small sensory fibre and autonomic, length-dependent, axonal neuropathy, while in late-onset cases, it presents with a lengthdependent sensorimotor axonal neuropathy involving all fibre sizes. Treatment is now available and includes TTR stabilizers, TTR amyloid removal as well as gene silencing, while gene editing therapies are on the way. Its timely diagnosis is of paramount importance for a better prognosis.

RNA-targeting and gene editing therapies for transthyretin amyloidosis

Transthyretin (TTR) is a tetrameric protein synthesized mostly by the liver and secreted into the plasma. TTR molecules can misfold and form amyloid fibrils in the heart and peripheral nerves, either as a result of gene variants in TTR or as an ageing-related phenomenon, which can lead to amyloid TTR (ATTR) amyloidosis. Some of the proposed strategies to treat ATTR amyloidosis include blocking TTR synthesis in the liver, stabilizing TTR tetramers or disrupting TTR fibrils. Small interfering RNA (siRNA) or antisense oligonucleotide (ASO) technologies have been shown to be highly effective for the blockade of TTR expression in the liver in humans. The siRNA patisiran and the ASO inotersen have been approved for the treatment of patients with ATTR variant polyneuropathy, regardless of the presence and severity of ATTR cardiomyopathy. Preliminary data show that therapy with patisiran improves the cardiac phenotype rather than only inducing disease stabilization in patients with ATTR variant polyneuropathy and concomitant ATTR cardiomyopathy, and this drug is being evaluated in a phase III clinical trial in patients with ATTR cardiomyopathy. Furthermore, ongoing phase III clinical trials will evaluate another siRNA, vutrisiran, and a novel ASO formulation, eplontersen, in patients with ATTR variant polyneuropathy or ATTR cardiomyopathy. In this Review, we discuss these approaches for TTR silencing in the treatment of ATTR amyloidosis as well as the latest strategy of genome editing with CRISPR-Cas9 to reduce TTR gene expression.

[Ten questions about transthyretin amyloidosis]

Systemic amyloidosis is a hereditary or acquired disease characterized by deposition of amyloid insoluble fibrils into body organs and tissues, causing structural abnormalities and organ dysfunction, i.e. heart failure. This disease is classified according to the precursor protein involved; immunoglobulin light chains, transthyretin and apolipoprotein A1 underlie the cardiac involvement. Amyloid cardiomyopathy is characterized by symmetric biventricular hypertrophy, preserved systolic function, and pronounced diastolic dysfunction. Although transthyretin-related cardiac amyloidosis has always been considered a rare disease, in the last few years it has been found to be one of the most common causes of hypertrophic cardiomyopathy, thanks to better diagnostic algorithms and considerable improvements in cardiac imaging. Achieving an early diagnosis is a challenge for the modern cardiologist since new disease-modifying therapies have been developed in recent years. This article aims to answer to the main questions about transthyretin-related cardiac amyloidosis: when to suspect it, how to diagnose it and how to treat it.

[Hereditary transthyretin amyloidosis - from symptomatic to curative treatment?]

Hereditary transthyretin (ATTRv) amyloidosis is a rare but life-threatening multi-systemic disease with clustering areas in, for example, northern Sweden. Until the 1990s, only symptomatic treatments were available but liver transplantation has, in selected patients, been a good therapeutic option since. The first disease-modifying drug for ATTRv amyloidosis was approved in 2011 and since then, the development of new therapeutic drugs has been rapid and successful. Two gene silencing therapies were approved for the disease in 2018, both showing a robust reduction in serum transthyretin levels and a satisfactory safety profile. Recently, CRISPR-Cas9 gene editing has also shown promising results in patients with ATTRv amyloidosis. The recent developments have had a paramount effect on the management of these patients, and will probably also have a significant positive effect on their life expectancy. However, treatment costs have skyrocketed, which implies future challenges.

[Treating hereditary neuropathies : a dream come true?]

Hereditary neuropathies have been the subject of recent major therapeutic advances. Treatments based on antisense oligonucleotides (ASO) and small interfering RNA (siRNA) have been developed and are now commercially available to treat hereditary transthyretin amyloidosis (hTTR) and porphyria. More recently, a CRISPR-Cas9 genomic editing treatment targeting the TTR gene has been developed and is being tested in patients with hTTR. Based on their success in hTTR and porphyria, innovative treatments targeting mRNA and DNA are being evaluated in other hereditary neuropathies, including Charcot-Marie-Tooth disease (CMT).

Accessibility to Occupational Therapy Services for Hereditary Transthyretin Amyloidosis

This study was designed to investigate the global utilization of occupational therapy (OT) services by patients with hereditary transthyretin amyloidosis (ATTRv) in Spain. The main objective was to find out whether these patients have access to OT services and the types of interventions being offered to them, together with their satisfaction and real benefits as users. We developed an online questionnaire which was distributed to patients with ATTRv in Spain through patient associations. Seventy-four patients with a diagnosis of ATTRv residing in Spain participated in the study. Thirteen had already used OT services at least once, felt that OT interventions improved their quality of life, would recommend OT services to others, and would return to see an occupational therapist. However, 61 had never used this type of service before. Of these, 35 knew what OT is and 13 declared that they considered that OT interventions in ATTRv could be positive for them. The results suggest that the use of OT services by ATTRv patients is low, mainly because of the lack of information about the occupational profile of individuals with this disease. The low response rate obtained for the survey limits generalization, and thus further research to confirm these preliminary findings is needed.

Evaluation and Management Strategies for GI Involvement with Amyloidosis

Amyloidosis is a heterogeneous disease that can cause a wide array of nonspecific symptoms when the gastrointestinal (GI) tract is involved, including weight loss, early satiety, change in bowel habits with diarrhea, constipation, or alternating bowel pattern. Endoscopy with biopsy for Congo red staining establishes the diagnosis and fibril subtyping helps to guide targeted treatment options. Light chain amyloidosis is the most frequent subtype found throughout the GI tract. Transthyretin amyloidosis is most likely to be found on rectal biopsy. Management of the symptoms of GI tract involvement with amyloidosis relate to addressing the underlying symptom complex that is produced and generally abstracted from the management of severe forms of functional GI disorders. Attention to improving symptom management and nutrition status can improve quality of life in these patients.

Cardiac Amyloidosis Treatment

Cardiac amyloidosis (CA) is a restrictive cardiomyopathy with a traditionally poor prognosis. Until recently, CA treatment options were limited and consisted predominantly of managing symptoms and disease-related complications. However, the last decade has seen significant advances in disease-modifying therapies, increased awareness of CA, and improved diagnostic methods resulting in earlier diagnoses. In this review, we provide an overview of current and experimental treatments for the predominant types of CA: transthyretin cardiac amyloidosis (ATTR-CA) and immunoglobulin light chain (AL)-mediated CA (AL-CA).

The mainstay of AL-CA treatment is proteasome inhibitor-based chemotherapy with daratumumab and, when feasible, autologous stem cell transplantation. For ATTR-CA, the stabilizer tafamidis is the only US Food and Drug Administration (FDA)-approved treatment. However, promising novel therapies on the horizon target various points in the ATTR-CA amyloidogenic cascade. These include transthyretin gene (TTR) silencing agents to prevent TTR formation, TTR tetramer stabilization and inhibition of oligomer aggregation to prevent fibril formation, anti-TTR fiber antibodies, and amyloid degradation. For end-stage CA, advanced interventions may need to be considered, including heart, heart-kidney, and, for hereditary ATTR-CA, heart-liver transplantation. Despite the evolution of treatment options, CA management remains complex due to patient frailty and therapeutic side effects or intolerance with advanced cardiac disease. This is particularly relevant for those with AL-CA, when active teamwork between the hematologist-oncologist and the cardiologist is critical for treatment success. Often, referral to an expert center is necessary for timely diagnosis, initiation of treatment, and participation in clinical trials.

Future Directions in Cardiac Amyloidosis

Just a few years ago, cardiac amyloidosis (CA) was rarely diagnosed. With poor treatment options and delayed and infrequent diagnoses, most patients who were eventually recognized to have CA were referred for hospice care. Now, the availability of sponsored genetic testing, increased use of nuclear scintigraphy, and widespread recognition have contributed to an increasing number of patients being diagnosed with transthyretin amyloid cardiomyopathy (ATTR-CM). Concomitantly, with the increased recognition of concurrent conditions (eg, carpal tunnel syndrome, lumbar stenosis, and low-flow, low-gradient aortic stenosis), specialists such as orthopedic surgeons and structural cardiologists are increasingly involved in diagnosing ATTR-CM.

Although the majority of patients are still being diagnosed either too late or having their diagnosis missed altogether, we have entered an exciting new era in the treatment of cardiac amyloidosis with improved diagnostic tools, disease recognition, and different therapeutic options for both ATTR and light-chain amyloidosis (AL). As a result, survival is improving, and we are no longer faced with a dualistic choice between hospice or organ transplant. The future goal is to develop anti-fibril therapies that will be safe and effective at removing deposited amyloid fibrils and restoring organs to their pre-amyloid state. For the millions of carriers of variant ATTR, enhanced testing followed by genetic editing may allow a cure even before patients develop clinical signs of the disease.

Cardiac amyloidosis: Description of a series of 143 cases

INTRODUCTION AND OBJECTIVES

Recently, there have been important advances in the diagnosis and treatment of cardiac amyloidosis (CA). Our aim was to provide an updated description of its 2 most frequent types: the transthyretin CA (ATTR-CA) and the light chain CA (AL-CA).

METHODS

Prospective registry of patients with CA diagnosed in 7 institutions in Galicia (Spain) between January 1, 2018 and June 30, 2020. Variables related to clinical characteristics, complementary tests, survival and causes of death were collected.

RESULTS

One hundred and forty-three patients with CA were consecutively included, 128 ATTR-CA (89.5%) and 15 AL-CA (10.5%). Mean age was 79.6±7.7 years and 23.8% were women. Most patients with ATTR-CA were diagnosed non-invasively (87.5%). On physical examination, 35.7, 35 and 7% had Popeye's sign, Dupuytren's contracture and macroglossia, respectively. Twelve-month and 24-month survival was 92.1 and 76.2% in the ATTR-CA group, and 78.6 and 61.1% in the AL-CA group (P=.152). The cause of death was cardiovascular in 80.8% of the cohort.

CONCLUSIONS

ATTR-CA can be diagnosed non-invasively in most cases and it is the most common type of CA in routine clinical practice. Furthermore, an increase in the short-term survival of CA appears to be observed, which could be due to advances related to its diagnosis and treatment.

Misconceptions and Facts About Cardiac Amyloidosis

Cardiac amyloidosis is an important clinical entity associated with significant morbidity and mortality. Although the signs and symptoms can be apparent early in the disease course, diagnoses are often made late because of inadequate recognition. A diagnosis of cardiac amyloidosis requires careful scrutiny of a patient's symptoms, an electrocardiogram, and imaging studies, including echocardiography and magnetic resonance imaging. Further evaluation is required through the measurement of serum and urine light chains and the use of bone scintigraphy imaging to differentiate transthyretin amyloidosis from light-chain cardiac amyloidosis. The available treatments have expanded tremendously in recent years and have improved outcomes in the population with this disorder. Thus, it has become increasingly important to diagnose cardiac amyloidosis and provide timely therapies. This article will clarify the various misconceptions about cardiac amyloidosis and provide a framework for primary care providers to better identify this disease in their practice.

Current and Emerging Therapies for Hereditary Transthyretin Amyloidosis: Strides Towards a Brighter Future

The past few years have witnessed an unprecedented acceleration in the clinical development of novel therapeutic options for hereditary transthyretin amyloidosis. Recently approved agents and drugs currently under investigation not only represent a major breakthrough in this field but also provide validation of the therapeutic potential of innovative approaches, like RNA interference and CRISPR-Cas9-mediated gene editing, in rare inherited disorders. In this review, we describe the evolving therapeutic landscape for hereditary transthyretin amyloidosis and discuss how this highly disabling and fatal condition is turning into a treatable disease. We also provide an overview of the molecular mechanisms involved in transthyretin (TTR) amyloid formation and regression, to highlight how a deeper understanding of these processes has contributed to the identification of novel treatment targets. Finally, we focus on major areas of uncertainty and unmet needs that deserve further efforts to improve long-term patients' outcomes and allow for a brighter future.

CRISPR-Cas9 In Vivo Gene Editing for Transthyretin Amyloidosis

BACKGROUND

Transthyretin amyloidosis, also called ATTR amyloidosis, is a life-threatening disease characterized by progressive accumulation of misfolded transthyretin (TTR) protein in tissues, predominantly the nerves and heart. NTLA-2001 is an in vivo gene-editing therapeutic agent that is designed to treat ATTR amyloidosis by reducing the concentration of TTR in serum. It is based on the clustered regularly interspaced short palindromic repeats and associated Cas9 endonuclease (CRISPR-Cas9) system and comprises a lipid nanoparticle encapsulating messenger RNA for Cas9 protein and a single guide RNA targeting TTR.

METHODS

After conducting preclinical in vitro and in vivo studies, we evaluated the safety and pharmacodynamic effects of single escalating doses of NTLA-2001 in six patients with hereditary ATTR amyloidosis with polyneuropathy, three in each of the two initial dose groups (0.1 mg per kilogram and 0.3 mg per kilogram), within an ongoing phase 1 clinical study.

RESULTS

Preclinical studies showed durable knockout of TTR after a single dose. Serial assessments of safety during the first 28 days after infusion in patients revealed few adverse events, and those that did occur were mild in grade. Dose-dependent pharmacodynamic effects were observed. At day 28, the mean reduction from baseline in serum TTR protein concentration was 52% (range, 47 to 56) in the group that received a dose of 0.1 mg per kilogram and was 87% (range, 80 to 96) in the group that received a dose of 0.3 mg per kilogram.

CONCLUSIONS

In a small group of patients with hereditary ATTR amyloidosis with polyneuropathy, administration of NTLA-2001 was associated with only mild adverse events and led to decreases in serum TTR protein concentrations through targeted knockout of TTR. (Funded by Intellia Therapeutics and Regeneron Pharmaceuticals; ClinicalTrials.gov number, NCT04601051.).

Progress and challenges in the treatment of cardiac amyloidosis: a review of the literature

Cardiac amyloidosis is a restrictive cardiomyopathy determined by the accumulation of amyloid, which is represented by misfolded protein fragments in the cardiac extracellular space. The main classification of systemic amyloidosis is determined by the amyloid precursor proteins causing a very heterogeneous disease spectrum, but the main types of amyloidosis involving the heart are light chain (AL) and transthyretin amyloidosis (ATTR). AL, in which the amyloid precursor is represented by misfolded immunoglobulin light chains, can involve almost any system carrying the worst prognosis among amyloidosis patients. This has however dramatically improved in the last few years with the increased usage of the novel therapies such as proteasome inhibitors and haematopoietic cell transplantation, in the case of timely diagnosis and initiation of treatment. The treatment for AL is directed by the haematologist working closely with the cardiologist when there is a significant cardiac involvement. Transthyretin (TTR) is a protein that is produced by the liver and is involved in the transportation of thyroid hormones, especially thyroxine and retinol binding protein. ATTR results from the accumulation of transthyretin amyloid in the extracellular space of different organs and systems, especially the heart and the nervous system. Specific therapies for ATTR act at various levels of TTR, from synthesis to deposition: TTR tetramer stabilization, oligomer aggregation inhibition, genetic therapy, amyloid fibre degradation, antiserum amyloid P antibodies, and antiserum TTR antibodies. Treatment of systemic amyloidosis has dramatically evolved over the last few years in both AL and ATTR, improving disease prognosis. Moreover, recent studies revealed that timely treatment can lead to an improvement in clinical status and in a regression of amyloid myocardial infiltration showed by imaging, especially by cardiac magnetic resonance, in both AL and ATTR. However, treating cardiac amyloidosis is a complex task due to the frequent association between systemic congestion and low blood pressure, thrombo-embolic and haemorrhagic risk balance, patient frailty, and generally poor prognosis. The aim of this review is to describe the current state of knowledge regarding cardiac amyloidosis therapy in this constantly evolving field, classified as treatment of the cardiac complications of amyloidosis (heart failure, rhythm and conduction disturbances, and thrombo-embolic risk) and the disease-modifying therapy.

Recommendations for the diagnosis and management of transthyretin amyloidosis with gastrointestinal manifestations

Transthyretin amyloid (ATTR) amyloidosis is an adult-onset, rare systemic disorder characterized by the accumulation of misfolded fibrils in the body, including the peripheral nerves, the heart and the gastrointestinal tract. Gastrointestinal manifestations are common in hereditary (ATTRv) amyloidosis and are present even before the onset of the polyneuropathy in some cases. Delays in diagnosis of ATTRv amyloidosis with gastrointestinal manifestations commonly occur because of fragmented knowledge among gastroenterologists and general practitioners, as well as a shortage of centers of excellence and specialists dedicated to disease management. Although the disease is becoming well-recognized in the societies of Neurology and Cardiology, it is still unknown for most gastroenterologists. This review presents the recommendations for ATTRv amyloidosis with gastrointestinal manifestations elaborated by a working group of European gastroenterologists and neurologists, and aims to provide digestive health specialists with an overview of crucial aspects of ATTRv amyloidosis diagnosis to help facilitate rapid and accurate identification of the disease by focusing on disease presentation, misdiagnosis and management of gastrointestinal symptoms.

Emerging therapy in light-chain and acquired transthyretin-related amyloidosis: an Italian single-centre experience in heart transplantation

AIMS

The prognosis for patients affected by light-chain cardiac amyloidosis and acquired transthyretin-related (TTR) amyloidosis is poor. Heart transplantation (HTx) could improve prognosis also enabling autologous stem cell transplantation (ASCT) in the first group.

METHODS AND RESULTS

A total of 36 patients affected by systemic amyloidosis have been referred to our centre from 2009 to 2019. Of these, nine had cardiac involvement: seven by light-chain amyloidosis and two by acquired TTR amyloidosis. None died while waiting for HTx. A specific internal protocol useful to select candidates and to monitor the organ involvement after HTx was developed. Median age at diagnosis was 54 years and 66% were male. The most common short-term complication after HTx was renal failure (44%), followed by acute cardiac rejection more than 2R (22%). ASCT was performed in six out of seven light-chain cardiac amyloidosis patients, with a median time of 6 months after HTx. Two patients affected by light-chain cardiac amyloidosis died due to amyloidosis relapse: one before undergoing ASCT. After a median follow-up of 31 (7-124) months, 1- and 5-year survival was 88 and 66% in the cardiac light-chain amyloidosis group. Conversely, 1- and 5-year survival was 100% in the acquired TTR amyloidosis group.

CONCLUSION

HTx may represent a valuable option in carefully selected patients. ASCT after HTx is an effective treatment that could decrease amyloidosis relapse in light-chain cardiac amyloidosis patients. A multidisciplinary approach is mandatory to select the best candidates and to obtain the most effective results with a specific surveillance follow-up protocol.

Inotersen for the Treatment of Hereditary Transthyretin Amyloidosis

Hereditary transthyretin amyloidosis (hATTR) is a rare autosomal dominant condition in which mutations in the transthyretin gene cause amyloid fibrils to develop and deposit into tissues, affecting primarily the nerves and heart causing polyneuropathy and cardiomyopathy respectively. Standard treatment has been liver transplants to try and eliminate the mutated transthyretin products as the liver is the main source of transthyretin production. A new drug named inotersen (brand name Tagsedi), also known as IONIS-TTR_RX, has been approved by the United States Food and Drug Agency, Health Canada, and European Commission in 2018, and introduced to the market for patients in stage 1 and stage 2 hATTR polyneuropathy. Inotersen is a second-generation antisense oligonucleotide with 2'-O-methoxyethyl modification designed to bind to the 3' untranslated region of the transthyretin mRNA in the nucleus of the liver cells. By doing so, it prevents the production of the mutant and wild-type forms of transthyretin, impeding the progression of the disease. In this article, the mechanism of action and safety profile of inotersen will be discussed along with some future directions following its approval.

Development of siRNA Therapeutics for the Treatment of Liver Diseases

Small interfering RNA (siRNA)-based therapeutics holds the promise to treat a wide range of human diseases that are currently incurable using conventional therapies. Most siRNA therapeutic efforts to date have focused on the treatment of liver diseases due to major breakthroughs in the development of efficient strategies for delivering siRNA drugs to the liver. Indeed, the development of lipid nanoparticle-formulated and GalNAc-conjugated siRNA therapeutics has resulted in recent FDA approvals of the first siRNA-based drugs, patisiran for the treatment of hereditary transthyretin amyloidosis and givosiran for the treatment of acute hepatic porphyria, respectively. Here, we describe the current strategies for delivering siRNA drugs to the liver and summarize recent advances in clinical development of siRNA therapeutics for the treatment of liver diseases.

TRANSTHYRETIN AMYLOIDOSIS THERAPIES: GUIDING THE FUTURE

Transthyretin (TTR) amyloidosis (ATTR) is a progressive condition characterized by multiorgan accumulation of amyloid deposits composed of transthyretin (TTR) fibrils. Over the past decades, despite being a rare disease, ATTR amyloidosis has enabled top-tier therapeutics. In the 90s, organ transplantation was the mainstream therapeutic option and fostered distinct approaches, such as combined liver-heart transplant and domino (sequential) liver transplantation. Likewise, several TTR molecule stabilizers were developed successfully. Over the past decade, oriented genetic therapies emerged to prevent, control, and, surprisingly, reverse amyloid deposition. Silencing the TTR gene using different strategies is flourishing, and ongoing trials continue to evaluate diverse approaches to optimize their application. The following perspective describes the currently available treatments for ATTR amyloidosis and the prospects on the potential application of these strategies in other medical fields.

Transthyretin Stabilization: An Emerging Strategy for the Treatment of Alzheimer's Disease?

Transthyretin (TTR), previously named prealbumin is a plasma protein secreted mainly by the liver and choroid plexus (CP) that is a carrier for thyroid hormones (THs) and retinol (vitamin A). The structure of TTR, with four monomers rich in β-chains in a globular tetrameric protein, accounts for the predisposition of the protein to aggregate in fibrils, leading to a rare and severe disease, namely transthyretin amyloidosis (ATTR). Much effort has been made and still is required to find new therapeutic compounds that can stabilize TTR ("kinetic stabilization") and prevent the amyloid genetic process. Moreover, TTR is an interesting therapeutic target for neurodegenerative diseases due to its recognized neuroprotective properties in the cognitive impairment context and interestingly in Alzheimer's disease (AD). Much evidence has been collected regarding the neuroprotective effects in AD, including through in vitro and in vivo studies as well as a wide range of clinical series. Despite this supported hypothesis of neuroprotection for TTR, the mechanisms are still not completely clear. The aim of this review is to highlight the most relevant findings on the neuroprotective role of TTR, and to summarize the recent progress on the development of TTR tetramer stabilizers.

Overview of treatments used in transthyretin-related hereditary amyloidosis: a systematic review

OBJECTIVE

To carry out a systematic review of the literature to analyse the efficacy and safety of treatments available or under investigation for amyloidosis due to mutations in the transthyretin gene (ATTR).

METHODS

A bibliographic search was carried out in the following electronic databases up to September 2017: PubMed, Cochrane Library and EMBASE. The inclusion criteria were: efficacy and/or safety studies conducted in humans, studies that included treatments, including treatments in the research phase, and studies that included 10 or more patients.

RESULTS

A total of 21 articles were included; 16 were clinical trials, eight of them (50%) phase III trials, and five were observational studies. Of the total number of studies selected, 11 were on tafamidis, four on diflunisal, two on liver transplantation, two on patisiran and two on other therapeutic alternatives. Of the 11 studies related to the drug, the pivotal trial, the results of its two extension studies and an additional post hoc analysis were selected. In addition, two phase III trials were included in specific populations, two phase II studies, one safety study and two observational studies. Regarding the four included studies related to the drug, one was the pivotal trial that gave the indication to diflunisal, another a safety summary of the pivotal trial, and the other two trials were carried out in specific populations, one in a Japanese population and another phase I trial in cardiac amyloidosis in the USA. As far as other alternatives are concerned, of the six studies included in this section, two were related to liver transplantation, two to patisiran and two to different therapeutic alternatives.

CONCLUSIONS

Sufficient evidence has not been found that demonstrates superiority among the available oral alternatives, diflunisal or tafamidis, in the treatment of ATTR. Direct comparisons between both drugs and pharmacoeconomic studies would be necessary to select the most efficient treatment.

Chance or challenge, spoilt for choice? New recommendations on diagnostic and therapeutic considerations in hereditary transthyretin amyloidosis with polyneuropathy: the German/Austrian position and review of the literature

Hereditary transthyretin amyloidosis is caused by pathogenic variants (ATTR_v) in the TTR gene. Alongside cardiac dysfunction, the disease typically manifests with a severely progressive sensorimotor and autonomic polyneuropathy. Three different drugs, tafamidis, patisiran, and inotersen, are approved in several countries, including the European Union and the United States of America. By stabilizing the TTR protein or degrading its mRNA, all types of treatment aim at preventing amyloid deposition and stopping the otherwise fatal course. Therefore, it is of utmost importance to recognize both onset and progression of neuropathy as early as possible. To establish recommendations for diagnostic and therapeutic procedures in the follow-up of both pre-symptomatic mutation carriers and patients with manifest ATTR_v amyloidosis with polyneuropathy, German and Austrian experts elaborated a harmonized position. This paper is further based on a systematic review of the literature. Potential challenges in the early recognition of disease onset and progression are the clinical heterogeneity and the subjectivity of sensory and autonomic symptoms. Progression cannot be defined by a single test or score alone but has to be evaluated considering various disease aspects and their dynamics over time. The first-line therapy should be chosen based on individual symptom constellations and contra-indications. If symptoms worsen, this should promptly implicate to consider optimizing treatment. Due to the rareness and variability of ATTR_v amyloidosis, the clinical course is most importantly directive in doubtful cases. Therefore, a systematic follow-up at an experienced center is crucial to identify progression and reassure patients and carriers.