Diagnosis and Screening of Patients with Hereditary Transthyretin Amyloidosis (hATTR): Current Strategies and Guidelines

Prevalence of valvular heart disease in cardiac amyloidosis and impact on survival

BACKGROUND

Limited data exists on the prognostic impact of valvular heart disease in cardiac amyloidosis (CA). We therefore sought to define the prevalence of valvular disease in patients with CA and assess the effects of significant valve disease on survival.

METHODS

This multi-center retrospective cohort study included consecutive patients with confirmed transthyretin (TTR) or light chain (AL) amyloidosis. Echocardiographic data closest to the date of amyloid diagnosis was reviewed, and severity was graded according to ASE guidelines. Kaplan-Meier survival analysis was performed to compare survival between patients with moderate or greater valve disease against those with mild or less disease.

RESULTS

We included 345 patients (median age 76 years; 73 % men; 110 AL, 235TTR). The median survival for the total patient cohort with cardiac amyloidosis was 2.92 years, with 30 % of patients surviving at five years after their diagnosis. Median survival comparing AL vs ATTR was 2.58 years vs 2.82 years (p = 0.67) The most common valvular abnormalities in the total cohort were mitral (62 %) and tricuspid (66 %).regurgitation There was a statistically significant difference in median survival between patients with no or mild MR compared to those with moderate or severe MR (2.92 years vs 3.35 years, p = 0.0047) (Fig. 5). There was a statistically significant difference in median survival in patients with no or mild TR compared to those with moderate or severe TR (3.35 years vs 2.3 years, p = 0.015).

CONCLUSION

Our study demonstrates a significant prevalence of mitral and tricuspid regurgitation in CA, with patients with moderate to severe MR and TR having a poorer prognosis.

Consensus recommendations on holistic care in hereditary ATTR amyloidosis: an international Delphi survey of patient advocates and multidisciplinary healthcare professionals

BACKGROUND

Hereditary transthyretin-mediated amyloidosis is a rare, progressive and potentially life-limiting multisystem disease, affecting every aspect of a patient's life.

OBJECTIVES

This online international Delphi survey aimed to evolve clinical-patient-led practical guidance, to inspire and encourage a holistic approach to care that is managed in specialist settings by multidisciplinary teams and supported by allied healthcare professionals (HCPs) and patient advocacy groups (PAGs).

DESIGN

A 14-member joint patient advocate-HCP primary panel was convened including representation from PAGs and key clinical specialties (neurology, cardiology, internal medicine, physiotherapy, clinical psychology, dietetics and specialist nursing). Guidance evolved on the care provision needed to support seven core goals: early diagnosis and treatment; disease monitoring and organisation of care; maintenance of physical and mental health; family-centred care and caregiver support; patient-doctor dialogue; access to social support and social networking.

PARTICIPANTS

From June to October 2022, 252 HCPs and 51 PAG representatives from 27 countries were invited to participate in a Delphi survey. Of the 122 respondents who answered at least one survey question, most were HCPs (100, 82%) from specialist centres; the remainder were PAG representatives (22, 18%).

MAIN OUTCOME MEASURE

Both level of agreement and feasibility in practice of each recommendation was tested by two anonymised online Delphi voting rounds.

RESULTS

Based on an a priori threshold for consensus of ≥75% agreement, the clinical-patient community endorsed all but one recommendation. However, only 17/49 (35%) recommendations were identified by most HCPs as a core part of routine care; the remainder (32/49 (65%)) were identified as part of core care by <50% of HCPs respondents, or as largely achievable by 30%-45% of HCPs. By comparison, PAGs recorded lower implementation levels.

CONCLUSIONS

Further consideration is needed on how to evolve multidisciplinary services (supported by allied HCPs and PAGs) to address the complex needs of those affected by this disease.

A narrative review and expert recommendations on the assessment of the clinical manifestations, follow-up, and management of post-OLT patients with ATTRv amyloidosis

Orthotopic liver transplantation (OLT) was the first treatment able to modify the natural course of hereditary transthyretin (ATTRv) amyloidosis, which is a rare and fatal disorder caused by the accumulation of misfolded transthyretin (TTR) variants in different organs and tissues and which leads to a progressive and multisystem dysfunction. Because the liver is the main source of TTR, OLT dramatically reduces the production of the pathogenic TTR variant, which should prevent amyloid formation and halt disease progression. However, amyloidosis progression may occur after OLT due to wild-type TTR deposition, especially in the nerves and heart. In this review, we discuss the disease features influencing OLT outcomes and the clinical manifestations of ATTRv amyloidosis progression post-OLT to improve our understanding of disease worsening after OLT and optimize the follow-up and clinical management of these patients. By conducting a literature review on the PubMed database, we identified patient characteristics that have been associated with worse post-OLT outcomes, including late-onset V50M and non-V50M variants, age >40 years, long disease duration, advanced neuropathy and autonomic dysfunction, and malnutrition. Regarding post-OLT mortality, deaths occurring within the first year after OLT were mainly associated with fatal graft complications and infectious diseases, whereas cardiovascular-related deaths usually occurred later. Considering the diverse clinical manifestations of ATTRv amyloidosis progression post-OLT, including worsening neuropathy and/or cardiomyopathy, autonomic dysfunction, and oculoleptomeningeal involvement, we present advice on the most relevant tests for assessing disease progression post-OLT. Finally, we discuss the use of new therapies based on TTR stabilizers and TTR mRNA silencers for the treatment of ATTRv amyloidosis patients post-OLT.

Brazilian consensus for diagnosis, management and treatment of hereditary transthyretin amyloidosis with peripheral neuropathy: second edition

Hereditary transthyretin amyloidosis with peripheral neuropathy (ATTRv-PN) is an autosomal dominant inherited sensorimotor and autonomic polyneuropathy with over 130 pathogenic variants identified in the TTR gene. Hereditary transthyretin amyloidosis with peripheral neuropathy is a disabling, progressive and life-threatening genetic condition that leads to death in ∼ 10 years if untreated. The prospects for ATTRv-PN have changed in the last decades, as it has become a treatable neuropathy. In addition to liver transplantation, initiated in 1990, there are now at least 3 drugs approved in many countries, including Brazil, and many more are being developed. The first Brazilian consensus on ATTRv-PN was held in the city of Fortaleza, Brazil, in June 2017. Given the new advances in the area over the last 5 years, the Peripheral Neuropathy Scientific Department of the Brazilian Academy of Neurology organized a second edition of the consensus. Each panelist was responsible for reviewing the literature and updating a section of the previous paper. Thereafter, the 18 panelists got together virtually after careful review of the draft, discussed each section of the text, and reached a consensus for the final version of the manuscript.

Predictors of cognitive dysfunction in hereditary transthyretin amyloidosis with liver transplant

BACKGROUND

Cognitive dysfunction is part of the broad spectrum of clinical manifestations in older untreated hereditary transthyretin amyloidosis patients with peripheral polyneuropathy.

OBJECTIVE

The objective of this study is to systematically explore cognitive dysfunction in ATTRV30M amyloidosis patients whose disease course was modified by liver transplant (LT).

METHODS

A series of 269 carriers of TTRVal30Met mutation treated with LT underwent a neuropsychological assessment. Clinical charts were reviewed to identify focal neurological episodes (FNEs), cognitive complaints and laboratory results. Chi-square and Mann-Whitney tests explored potential predictors of cognitive dysfunction.

RESULTS

Cognitive dysfunction was identified in 35 patients (13%)-14 (5%) had mild and 21 (8%) had moderate dysfunction. In comparison to normal cognition, both mild and moderate cognitive dysfunction patients had older age, higher mPND score and elevated NT-proBNP and Cystatin C values. Mild cognitive dysfunction was associated with longer disease duration and history of FNEs, whereas moderate dysfunction was related to older age at disease onset and more cognitive complaints and depression symptoms.

CONCLUSIONS

Consistent with the natural history of the disease, older age and higher severity of the disease are significantly associated and potentially predictors of cognitive dysfunction in ATTRV30M patients treated with LT. The level of cognitive dysfunction may depend on some clinical variables.

Liver-directed drugs for transthyretin-mediated amyloidosis

Transthyretin-mediated amyloidosis (ATTR) is a rare, under-recognized, progressively debilitating, fatal disease caused by the aggregation and extracellular deposition of amyloid transthyretin (TTR) fibrils in multiple organs and tissues throughout the body. TTR is predominantly synthesized by the liver and normally circulates as a homotetramer, while misfolded monomers aggregate to form amyloid fibrils. One strategy to treat ATTR amyloidosis is to reduce the amount of TTR produced by the liver using drugs that directly target the TTR mRNA or gene. This narrative review focuses on how TTR gene silencing tools act to reduce TTR production, describing strategies for improved targeted delivery of these agents to hepatocytes where TTR is preferentially expressed. Antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs), termed RNA silencers, cause selective degradation of TTR mRNA, while a TTR gene editing tool reduces TTR expression by introducing nonsense mutations into the TTR gene. Two strategies to facilitate tissue-specific delivery of these nucleic acid-based drugs employ endogenous receptors expressed by hepatocytes. Lipid nanoparticles (LNPs) that recruit apolipoprotein E support low-density lipoprotein receptor-mediated uptake of unconjugated siRNA and are now used for CRISPR gene editing tools. Additionally, conjugating N-acetylgalactosamine (GalNAc) moieties to ASOs or siRNAs facilitates receptor-mediated uptake by the asialoglycoprotein receptor. In summary, ATTR is a progressive disease with various clinical manifestations due to TTR aggregation, deposition, and amyloid formation. Receptor-targeted ligands (eg, GalNAc) and nanoparticle encapsulation (eg, LNPs) are technologies to deliver ASOs, siRNAs, and gene editing tools to hepatocytes, the primary location of TTR synthesis.

Toxic Misfolded Transthyretin Oligomers with Different Molecular Conformations Formed through Distinct Oligomerization Pathways

Protein aggregation is initiated by structural changes from native polypeptides to cytotoxic oligomers, which form cross-β structured amyloid. Identification and characterization of oligomeric intermediates are critically important for understanding not only the molecular mechanism of aggregation but also the cytotoxic nature of amyloid oligomers. Preparation of misfolded oligomers for structural characterization is, however, challenging because of their transient, heterogeneous nature. Here, we report two distinct misfolded transthyretin (TTR) oligomers formed through different oligomerization pathways. A pathogenic TTR variant with a strong aggregation propensity (L55P) was used to prepare misfolded oligomers at physiological pH. Our mechanistic studies showed that the full-length TTR initially forms small oligomers, which self-assemble into short protofibrils at later stages. Enzymatic cleavage of the CD loop was also used to induce the formation of N-terminally truncated oligomers, which was detected in ex vivo cardiac TTR aggregates extracted from the tissues of patients. Structural characterization of the oligomers using solid-state nuclear magnetic resonance and circular dichroism revealed that the two TTR misfolded oligomers have distinct molecular conformations. In addition, the proteolytically cleaved TTR oligomers exhibit a higher surface hydrophobicity, suggesting the presence of distinct oligomerization pathways for TTR oligomer formation. Cytotoxicity assays also revealed that the cytotoxicity of cleaved oligomers is stronger than that of the full-length TTR oligomers, indicating that hydrophobicity might be an important property of toxic oligomers. These comparative biophysical analyses suggest that the toxic cleaved TTR oligomers formed through a different misfoling pathway may adopt distinct structural features that produce higher surface hydrophobicity, leading to the stronger cytotoxic activities.

Long-Term Treatment Effects of Inotersen on Health-Related Quality of Life in Patients with hATTR Amyloidosis with Polyneuropathy: Analysis of the Open-Label Extension of the NEURO-TTR Trial

INTRODUCTION/AIMS

Hereditary transthyretin-mediated amyloidosis with polyneuropathy (hATTR-PN) progressively affects patients' functionality and compromises health-related quality of life (HRQL). The aim of this study was to quantify the projected long-term treatment effects of inotersen versus placebo on HRQL measures.

METHODS

The inotersen phase 2/3 randomized, double-blind, placebo-controlled trial NEURO-TTR (NCT01737398, 66 weeks) and subsequent open-label extension (OLE; NCT02175004, 104 weeks) included 172 patients (inotersen = 112; placebo = 60). Placebo double-blind period and overall inotersen-inotersen (double-blind/OLE) treatment period (170 weeks) data were used to extrapolate long-term placebo-placebo effect using mixed-effects models with repeated measures. Changes from baseline in the Norfolk Quality of Life-Diabetic Neuropathy (QoL-DN) and Short-Form 36 Health Survey (SF-36v2) in hATTR-PN were estimated. Differences in changes were compared between the inotersen/inotersen and extrapolated placebo/placebo arms.

RESULTS

Inotersen-inotersen patients maintained their HRQL with an observed change ranging from 10.3% improvement (Norfolk QoL-DN item "Pain Kept You Awake at Night") to 11.6% deterioration (SF-36v2 Activities of Daily Living subdomain). The extrapolated placebo-placebo results suggest greater deterioration over time compared to inotersen-inotersen treatment on Norfolk QoL-DN total score (23.6, [95% CI: 8.9-38.3], p < 0.01), Activities of Daily Living (4.6, [2.0-7.3], p < 0.001), and item "Pain Kept You Awake at Night" (1.2, [0.4-1.9], p < 0.01). Similarly, greater deterioration was expected for SF-36v2 Physical Component Summary (8.0, [3.2-12.8], p < 0.01), Bodily Pain (7.8, [2.0-13.5], p < 0.01), and Physical Functioning domain (10.6, [5.5-15.6], p < 0.0001).

DISCUSSION

Long-term (>3 years) inotersen treatment was associated with slowing, and in some domains halting, of deterioration in key HRQL outcomes, particularly physical functioning and pain measures. This article is protected by copyright. All rights reserved.

Addressing the routine failure to clinically identify monogenic cases of common disease

Changes in medical practice are needed to improve the diagnosis of monogenic forms of selected common diseases. This article seeks to focus attention on the need for universal genetic testing in common diseases for which the recommended clinical management of patients with specific monogenic forms of disease diverges from standard management and has evidence for improved outcomes.We review evidence from genomic screening of large patient cohorts, which has confirmed that important monogenic case identification failures are commonplace in routine clinical care. These case identification failures constitute diagnostic misattributions, where the care of individuals with monogenic disease defaults to the treatment plan offered to those with polygenic or non-genetic forms of the disease.The number of identifiable and actionable monogenic forms of common diseases is increasing with time. Here, we provide six examples of common diseases for which universal genetic test implementation would drive improved care. We examine the evidence to support genetic testing for common diseases, and discuss barriers to widespread implementation. Finally, we propose recommendations for changes to genetic testing and care delivery aimed at reducing diagnostic misattributions, to serve as a starting point for further evaluation and development of evidence-based guidelines for implementation.

Changes in nerve conduction studies predate clinical symptoms onset in early onset Val30Met hereditary ATTR amyloidosis

BACKGROUND AND PURPOSE

Hereditary amyloidosis related to transthyretin (ATTR) is a rare and progressive disease that, despite the phenotypic heterogeneity, a length-dependent sensorimotor axonal neuropathy (ATTR-PN) is the classic hallmark. Timely diagnosis is paramount for early treatment implementation.

METHODS

Sixty-nine asymptomatic gene carriers (Val30Met) were assessed during a 4-year period to identify those remaining asymptomatic versus those converting to ATTRV30M-PN. Conversion to symptomatic was defined as presenting with two definite symptoms of ATTRV30M-PN. Composite neurophysiological scores of sensory (SNS), motor (MNS), and sympathetic skin response (SSRS) amplitudes were used to assess neuropathy progression. We used mixed-effects modeling and ordinal logistic regression to assess neurophysiological evolution over time.

RESULTS

Of all asymptomatic gene carriers, 55.1% (n = 38/69) converted over the period of this analysis. The progression of the SNS relative to baseline was different between groups (asymptomatic gene carriers vs. converters), the decline being greater in the converter group (time × group interaction p = 0.040), starting about 2 years before symptom onset. No significant change occurred regarding MNS or SSRS. Moreover, the percentage of cases with an annual decline on the SNS of at least 25%, gradually and significantly increased in the converter group, representing a 1.92 increase in risk of developing symptoms for those with such reduction on the last evaluation.

CONCLUSIONS

A simple composite neurophysiological sum score can predict the onset of ATTRV30M-PN symptoms by as much as 2 years, highlighting the importance of a systematic follow-up of asymptomatic gene carriers, allowing a timely diagnosis, and management of symptomatic disease.

Multidisciplinary Approaches for Transthyretin Amyloidosis

Amyloidosis caused by systemic deposition of transthyretin (TTR) is called ATTR amyloidosis and mainly includes hereditary ATTR (ATTRv) amyloidosis and wild-type ATTR (ATTRwt) amyloidosis. Until recently, ATTRv amyloidosis had been considered a disease in the field of neurology because neuropathic symptoms predominated in patients described in early reports, whereas advances in diagnostic techniques and increased recognition of this disease revealed the presence of patients with cardiomyopathy as a predominant feature. In contrast, ATTRwt amyloidosis has been considered a disease in the field of cardiology. However, recent studies have suggested that some of the patients with ATTRwt amyloidosis present tenosynovial tissue complications, particularly carpal tunnel syndrome, as an initial manifestation of amyloidosis, necessitating an awareness of this disease among neurologists and orthopedists. Although histopathological confirmation of amyloid deposits has traditionally been considered mandatory for the diagnosis of ATTR amyloidosis, the development of noninvasive imaging techniques in the field of cardiology, such as echocardiography, magnetic resonance imaging, and nuclear imaging, enabled nonbiopsy diagnosis of this disease. The mechanisms underlying characteristic cardiac imaging findings have been deciphered by histopathological studies. Novel disease-modifying therapies for ATTR amyloidosis, such as TTR stabilizers, short interfering RNA, and antisense oligonucleotides, were initially approved for ATTRv amyloidosis patients with polyneuropathy. However, the indications for the use of these disease-modifying therapies gradually widened to include ATTRv and ATTRwt amyloidosis patients with cardiomyopathy. Since the coronavirus disease 2019 (COVID-19) pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, occurred, the minimization of hospital visits and telemedicine have become increasingly important. As older age and cardiovascular disease are major factors associated with increased disease severity and mortality of COVID-19, many ATTR amyloidosis patients are at increased risk of disease aggravation when they are infected with SARS-CoV-2. From this viewpoint, close interspecialty communication to determine the optimal interval of evaluation is needed for the management of patients with ATTR amyloidosis.