First European consensus for diagnosis, management, and treatment of transthyretin familial amyloid polyneuropathy

A Brief Review of Inherited Neuropathies: A Perspective from Saudi Arabia

Inherited neuropathies are a heterogeneous group of disorders that affect the peripheral nervous system, leading to motor, sensory, and autonomic dysfunction. These disorders are classified into various subgroups, including hereditary sensory and motor neuropathies, distal hereditary motor neuropathies, hereditary sensory and autonomic neuropathies, and more complex forms. Advances in genetic testing, particularly next-generation sequencing (NGS), have significantly improved the identification of these disorders. Emerging therapies, such as gene therapy, small molecule therapies, and antisense oligonucleotides, offer promising treatment options. However, current treatments remain limited, and their clinical benefits in humans are not yet fully established. This review provides a comprehensive overview of recent developments and evolving therapeutic options for hereditary neuropathies, focusing on gene therapy, small molecule therapies, and antisense oligonucleotides. It also highlights the current state of inherited neuropathies in Saudi Arabia, emphasizing the need for national guidelines, patient registries, and collaborative research efforts. By integrating advanced genomic technologies and fostering international collaboration, we can improve the diagnosis, management, and treatment outcomes for patients with inherited neuropathies.

Intraepineurial Fat Fraction: A Novel MR Neurography-Based Biomarker in Transthyretin Amyloidosis Polyneuropathy

INTRODUCTION

Hereditary transthyretin amyloid polyneuropathy (ATTRv-PN) is a rare and progressive neurodegenerative disorder characterized by axonal neuropathy and amyloid deposits. Early detection of disease onset and progression is crucial for timely therapeutic intervention. Quantitative MRI (qMRI) can be used to measure potential biomarkers. Intraepineurial fat fraction (ieFF) may reflect lipid droplets in amyloid deposits as described in histological studies or the replacement of nerve fiber loss with fatty-rich interfascicular epineurium. This study investigates the potential utility of ieFF as a novel imaging-related biomarker in differentiating ATTRv-PN, asymptomatic carriers (ATTRv-C), and healthy controls (HCs).

METHODS

Fifty-three patients with TTR mutations were imaged (31 ATTRv-PN patients, 22 ATTRv-C, and 24 HC) and both clinical and electrophysiological parameters were quantified. 3D volume, ieFF, and magnetization transfer ratio (MTR) were quantified in sciatic and tibial nerves using qMRI.

RESULTS

Symptomatic ATTRv-PN patients exhibited significantly higher ieFF in both sciatic (32.4% IQR [24.4-38.1]) and tibial nerves (13.7%, IQR [9.97-20.7]) compared to controls (sciatic 22.3%, IQR [16.6-28.5]; tibial 9.74%, IQR [6.36-12.5]) (p < 0.05). ieFF values were positively correlated in both uni and multivariate analyses with the main clinical scores and electrophysiological measures. ATTRv-C also showed increased ieFF values compared to controls (p < 0.05). Comparatively, MTR and nerve volumes exhibited less pronounced differences across groups.

CONCLUSION

This study demonstrates that ieFF effectively differentiates symptomatic and asymptomatic ATTRv patients from HC and correlates strongly with electrophysiological and clinical severity parameters. Furthermore, we compare ieFF with conventional qMRI biomarkers, highlighting its superior potential for monitoring nerve structural impairment.

Integrated specialty care for amyloidosis: a scoping review using the Consolidated Framework for Implementation Research

BACKGROUND

Amyloidosis is a complex and rare disease requiring specialized, multidisciplinary care to effectively manage its diverse manifestations. Existing evidence underscores the benefits of such care, linked to improved patient outcomes and clinician satisfaction. With the rising incidence of amyloidosis diagnoses and rapid advancements in treatment, the need for coordinated, expert-led care is increasing. However, implementing these centers is challenging due to resource allocation and inter-specialty collaboration. While resource allocation is a known hurdle, there has not been a comprehensive review of all the barriers and facilitators to establishing these clinics. This scoping review aims to identify the barriers and facilitators related to the implementation of coordinated, multidisciplinary specialty care clinics in amyloidosis management.

METHODS

An electronic search was conducted in Medline, Embase, and CINAHL for studies published in English from 2013 to 2023, supplemented by a grey literature search. The inclusion criteria focused on studies discussing multidisciplinary clinical environments for amyloidosis care, particularly light-chain (AL) and transthyretin amyloidosis (TTR). Exclusion criteria included books, opinion pieces, dissertations, and conference abstracts. Data were analyzed and synthesized using a narrative synthesis approach, guided by the Consolidated Framework for Implementation Research (CFIR), and reported according to PRISMA-ScR guidelines.

RESULTS

The search resulted in 1547 findings. After screening with Covidence, 7 papers were included in the final review. Independent reviewers screened and extracted the papers. Key facilitators identified include access to experts, adequate staffing, secure funding, partnerships with patient advocacy groups, and robust processes for multidisciplinary communication. Barriers primarily relate to the complexity of care, a lack of standardized protocols, difficulties in communication and coordination between providers, and challenges in training and maintaining knowledgeable care providers. The review also revealed significant gaps in existing research.

CONCLUSIONS

This review enhances understanding of the barriers and facilitators in establishing amyloidosis specialty clinics. Addressing these barriers and leveraging facilitators are crucial for shaping the future of amyloidosis care. These insights support a model for implementing integrated care for this growing patient population and highlight the need for further research to support policy development and effective implementation of these specialized clinics.

Diagnosis of hereditary transthyretin amyloidosis in patients with suspected chronic inflammatory demyelinating polyneuropathy unresponsive to intravenous immunoglobulins: results of a retrospective study

BACKGROUND AND AIMS

Hereditary transthyretin amyloidosis (ATTRv) should be considered in patients diagnosed with intravenous immunoglobulin (IVIg)-resistant chronic inflammatory demyelinating polyradiculoneuropathy (IVIg-NR CIDP). In this 1-year long, retrospective, multicentric study, an online questionnaire was sent to 1100 French healthcare professionals (HCPs) investigating: (i) how many IVIg-NR CIDP patients they followed; (ii) how many IVIg-NR CIDP patients had undergone TTR gene analysis; and (iii) how many IVIg-NR CIDP patients were eventually diagnosed with ATTRv. The questionnaire was sent every 3 months for 1 year and contained information on ATTRv clinical manifestations and diagnosis.

RESULTS

One-hundred and ten (10%) HCPs responded. A total of 2131 patients with CIDP were identified, including 315 (22.1%) with IVIg-NR CIDP. TTR gene analysis was performed in 144 patients and was positive in 43 cases (29.9%).

CONCLUSIONS

This study demonstrates that ATTRv should be investigated systematically in patients diagnosed with IVIg-NR CIDP. HCP-directed information campaigns are useful for modifying diagnostic practices.

Minimal invasive biopsies are highly sensitive for amyloid detection in hereditary transthyretin amyloidosis with polyneuropathy

OBJECTIVE

To assess the effectiveness of labial minor salivary gland biopsy (LSGB) alone or in combination with punch skin biopsy (SB) for the detection of amyloid deposits in hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN).

METHODS

In this single-center retrospective study, Congo red staining of minimal invasive LSGB (4 mm) and SB (3 mm) was assessed in ATTRv-PN patients consecutively evaluated between 2012 and 2023.

RESULTS

Histopathological data of 171 ATTRv-PN, including 49 early-onset p.Val50Met, 58 late-onset p.Val50Met, and 64 non-p.Val50Met, were reviewed. LSGB and SB identified amyloid deposits in 123/171 (72%) and 131/171 (77%) patients respectively (p = 0.2). Combining LSGB and SB increased the amyloid detection rate to 150/171 (88%), especially in late-onset p.Val50Met (48/58 [83%]) and non-p.Val50Met patients (55/64 [86%]). LSGB and SB have a similar rate of detection of amyloid depositions in early onset p.Val50Met patients (94%). Also, the LSGB/SB combination identified amyloidosis in 89% (55/62) of early-stage ATTRv-PN patients.

CONCLUSIONS

In our study, combining LSGB and SB allowed the detection of amyloid deposits in 88% of ATTRv-PN patients. LSGB/SB analysis may be of major interest to confirm entry in the disease at very early-stage ATTRv-PN, with implications in disease-modifying treatment initiation.

Diagnostic delay in patients with sporadic hereditary transthyretin-mediated amyloidosis

BACKGROUND

Hereditary transthyretin-mediated amyloidosis (ATTRv amyloidosis) is a rare progressively incapacitating condition with a wide range of genotype/phenotype presentations. It is frequently diagnosed late in its course, particularly in sporadic cases.

OBJECTIVES

Analysing predictors of diagnostic delay in this subpopulation should be, therefore, a priority.

METHODS

109 apparently sporadic ATTRv amyloidosis patients followed in a reference centre in Hospital de Santa Maria (ULS Santa Maria-CAML), in Lisbon, were studied. Time from symptom onset to diagnosis, age, sex, municipality of origin and initial symptoms were obtained. Diagnostic delay was compared between different decades with a Kruskal-Wallis test, and its predictors were evaluated in a univariate model followed by a binary logistic regression analysis to calculate the adjusted odds ratio.

RESULTS

The median diagnostic delay was 1262 days. There was a non-significant difference in diagnostic delay between the 80 s, 90 s, 2000s and 2010s decades. There was a non-significant trend for a longer diagnostic delay in woman and in patients having no neurologic symptoms at onset.

CONCLUSION

There is an important diagnostic delay in sporadic cases of ATTRv amyloidosis. Awareness should be spread among clinicians regarding the various manifestations of this disease, stressing the importance of family history and epidemiological data.

Transthyretin-Related Familial Amyloidosis Polyneuropathy with Spinal Cord Damage: A Case Report

Introduction

Transthyretin protein-related familial amyloidosis polyneuropathy (TTR-FAP) is an autosomal dominant genetic disease caused by mutations in the TTR gene. The disease is characterized primarily by peripheral and autonomic nerve damage. Disease progression is associated with frequent involvement of the heart, lungs, kidneys, eyes, and other organs. The most common TTR mutation is c.148G>A (p.Val50Met), although the FAP resulting from the mutation rarely involves the spinal cord.

Patient Concerns

A 68-year-old man was diagnosed with the TTR c.148G>A (p.Val50Met) mutation by ultrasound, pathological, and genetic analyses. He presented with a late-onset, complicated spinal cord injury. The diagnostic process was tortuous, and despite the administration of regular treatment (conventional drugs, cardiac pacemaker, and the specific drug clofenadifen), the patient died.

Interventions

To confirm TTR-FAP, ultrasound, MRI, pathological, and genetic tests were performed.

Outcomes

The patient ultimately died of heart failure 7.5 years after the initial onset of symptoms.

Conclusion

The patient presented with unusual symptoms of spinal cord injury, and despite a long and arduous diagnostic process and administration of standard treatment for over seven years, the outcome was poor. It is thus recommended that clinicians pay attention to the identification of rare diseases with timely imaging, pathological, and genetic testing, to avoid poor outcomes.

Quantitative muscle MRI combined with AI-based segmentation as a follow-up biomarker for ATTRv patients: A longitudinal pilot study

BACKGROUND AND OBJECTIVES

Intramuscular fat fraction (FF), assessed using quantitative MRI (qMRI), has emerged as a promising biomarker for hereditary transthyretin amyloidosis (ATTRv) patients. Currently, the main drawbacks to its use in future therapeutic trials are its sensitivity to change over a short period of time and the time-consuming manual segmentation step to extract quantitative data. This pilot study aimed to demonstrate the suitability of an Artificial Intelligence-based (AI) segmentation technique to assess disease progression in a real-life cohort of ATTRv patients over 1 year.

METHODS

Fifteen ATTRv patients were included in this monocentric, observational, prospective study. FF, magnetization transfer ratio (MTR), and quantitative T2 were extracted from patients' lower limb qMRI at two time points, 1 year apart, at thigh and leg levels. qMRI parameters were correlated with clinical and electrophysiological parameters assessed at the same time.

RESULTS

Global FF at leg level significantly progressed over 1 year: +1.28 ± 2.62% (p = 0.017). At thigh level, no significant change in global FF, MTR, or T2 was measured. The leg FF was strongly correlated with the main clinical and electrophysiological scores.

CONCLUSION

AI-based CNN network segmentation combined with qMRI can be used to obtain quantitative metrics for longitudinal studies in ATTRv patients. Global FF at the leg level seems to be the most sensitive MRI biomarker to track disease progression in a 1-year period. Larger studies with treatment-specific groups will now be necessary to determine the place of qMRI markers compared to the current clinical and electrophysiological scores.

Real-life experience with disease-modifying drugs in hereditary transthyretin amyloid polyneuropathy: A clinical and electrophysiological appraisal

INTRODUCTION

New treatments have dramatically improved the prognosis for Hereditary Transthyretin Amyloid Polyneuropathy (ATTRv-PN). However, there is a lack of routine follow-up studies outside of therapeutic trials. Our aim was to report the long-term clinical and electrophysiological evolution of a cohort of ATTRv-PN patients and to determine which biomarkers are most sensitive to change.

METHODS

We retrospectively collected neuropathy impairment scale (NIS), polyneuropathy disability scale (PND), overall neuropathy limitation scale (ONLS), rash built overall disability scale (RODS), electrodiagnostic data, motor unit number index (MUNIX), troponin and N-terminal pro-brain natriuretic peptide levels. Electrophysiological worsening was defined as a 20% decrease in previous values.

RESULTS

Thirty-five patients, with a median age of 58 (interquartile ranges 42-71) years, were followed for a median of 36 (24-48) months. All patients received a transthyretin stabiliser, gene silencer or liver transplant. Overall assessment of the cohort showed clinical, biological and electrophysiological stability. However, on an individual basis, NIS worsened in 45% of patients (14/31), ONLS in 46% (13/28), PND in 28% (9/32) and RODS in 39% (11/28) at the last follow-up. Motor amplitude sum score decreased in 33% (11/33), amplitude recorded on tibialis anterior muscle in 44% (12/27), sensory amplitude sum score in 39% (11/28) and MUNIX sum score in 27% (7/26).

CONCLUSIONS

Overall effectiveness of ATTRv-PN treatments in routine care is good. However, individual assessments show up to 40% deterioration over time. Electrophysiological measures are valuable monitoring tools but are not more sensitive to change than clinical scores. Results must be confirmed in larger cohorts.

Management of Hereditary Transthyretin Amyloidosis (ATTRv) Patients and Asymptomatic Carriers in Spain: The EMPATIa Study

Background: Hereditary transthyretin amyloidosis (ATTRv) is an autosomal-dominant systemic disease, where amyloid fibrils accumulate especially in the peripheral and autonomic nervous systems and in the heart. The aim of the present work was to outline the follow-up and type of management received by asymptomatic carriers (ACs) and Coutinho stage 1 ATTRv patients in Spain. Methods: A cross-sectional, non-interventional study was conducted throughout seven experienced hospitals in Spain. A total of 86 ACs without neurological symptoms and 19 Coutinho stage 1 ATTRv patients diagnosed 12 months before their enrollment were included. Clinical and demographic data, red flags, and neurological and cardiological evaluations were gathered. In addition, site variables were collected from four centers to describe the clinical management of ATTRv. Results: ATTRv clinical management varied depending on the center setting but was primarily overseen by neurology and internal medicine, which were responsible for the holistic follow-up of ACs and patients. Routinely, neurologists, neurophysiologists, cardiologists, and internal medicine conducted the follow-up. Specialties involved in initial AC assessment were neurophysiologists and cardiologists in 100% of cases, neurologists (75%), internists and geneticists (50%), and ophthalmologists (25%). A review of the medical tests performed proved an exhaustive management of the study population. Stable patients were followed up every 6 months, while those under evolution were monitored every 3-6 months. The frequency of monitoring of ACs was annual, and carriers classified with doubtful disease onset were visited every 3-6 months. Conclusions: The EMPATIa study provides valuable insights into the management of ATTRv in a real-world clinical setting in highly experienced hospitals in Spain. It demonstrates that multidisciplinary practice and enhanced disease awareness may lead to a reduction in diagnostic delay.

A Comparative Study of the Electroneurographic Findings in Amyloidotic Polyneuropathy in Patients with Light-Chain Amyloidosis and Glu54Gln Transthyretin Amyloidosis

Background and Objectives: Amyloidosis is a disorder characterized by the abnormal folding of proteins, forming insoluble fibrils that accumulate in tissues and organs. This accumulation disrupts normal tissue architecture and organ function, often with serious consequences, including death if left untreated. Light-chain amyloidosis (AL) and hereditary transthyretin-type amyloidosis (hATTR) are two of the most common types. In amyloidosis, peripheral nervous system involvement is a significant diagnostic feature, particularly when it manifests as polyneuropathy, carpal tunnel syndrome (CTS), and dysautonomia. These neurological symptoms often point to the involvement of amyloid deposits in the peripheral and autonomic nervous systems, which can help identify and differentiate between the various types of amyloidosis. Materials and Methods: This retrospective study focused on the evolution of electrophysiological parameters in two groups: AL (n = 22) and hATTR-Glu54Gln patients (n = 14), with mixed axonal polyneuropathy. Patients were followed for two consecutive years to assess disease progression. The PND scale (polyneuropathy disability) was also used to assess motor impairment for each patient. Results: In our study AL amyloidosis patients presented with mixed, axonal polyneuropathy associated with CTS in 63.6% of cases and cardiomyopathy (45.5%). Serial EMGs (electromyography) showed decreased motor amplitudes of the common peroneal and tibial nerves and sensory amplitude of the superficial peroneal nerve, with mostly preserved conduction velocities. The patients maintained stage I PND throughout the monitoring period. The entire hATTR group displayed mixed, axonal polyneuropathy and cardiomyopathy; 85.7% of them had CTS, and 42.9% had orthostatic hypotension. EMG data showed decreased motor amplitudes of the tibial and common peroneal nerves, decreased sensory amplitudes of the superficial peroneal nerve, and mildly reduced conduction velocities, with significant progression at 12 and 24 months. The patients displayed additional reduced muscle strength, some reaching stage 3A and 3B-PND at the end of the study. Conclusions: The amyloidotic polyneuropathy found in the groups was similar in its axonal, sensory-motor, and length-dependent characteristics, but the study showed significant differences in its progression, with more abrupt changes in the hATTR-Glu54Gln group. The amyloidosis AL patients remained in stage 1 PND, while the hATTR-Glu54Gln patients progressed to stage 3 PND at 24 months.

Neck triangle nerve enlargement in hereditary transthyretin amyloidosis correlates with changes in the autonomic, cardiac, and gastrointestinal systems

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRv) is a hereditary disease that affects multiple bodily systems. Although sonography generally reveals enlargement of nerves in the limbs, the brachial plexus, and vagus nerve, the clinical significance of these findings remains unclear.

METHODS

We performed sonographic measurements of the median nerve, cervical spinal nerves at the C5-C7 level, and the vagus nerve in patients with ATTRv and healthy controls. Clinical profiles and cardiac and gastrointestinal examination results were also collected for linear regression analysis.

RESULTS

We recruited 47 patients with ATTRv (males/females: 34/13, age: 65.6 ± 5.3 years). The sampled segments were all significantly larger than those of the controls. In the clinical profiles, the sum of the Z scores of the neck triangle nerves (cervical spinal nerves and vagus nerve) and of all nerves (cervical spinal nerves, vagus nerve, and median nerve at the wrist) significantly correlated with the familial amyloid polyneuropathy stage, onset of autonomic nervous system (ANS) symptoms, and autonomic symptom scores. On cardiac examinations, several ultrasonography and magnetic resonance imaging parameters (primarily those that reflect heart volume) were found to be significantly correlated with the sum of the Z scores of the cervical spinal nerves but not with the Z score of the vagus nerve. In gastrointestinal evaluation, the cross-sectional area of the vagus nerve was correlated with gastric emptying time parameters on scintigraphy.

CONCLUSIONS

Neck triangle nerve enlargement on sonography correlated with parameters related to ANS dysfunction, indicating that nerve enlargement observed on ultrasonography may serve as a potential surrogate biomarker of ATTRv.

Hereditary transthyretin amyloidosis presenting with prominent autonomic dysfunction

A 56-year-old man reported 2 years of slowly progressive exertional fatigue, presyncope, paraesthesia, generalised weakness and nocturnal bowel frequency. He had an abnormal Valsalva ratio and significant postural hypotension. Serum N-terminal pro-B-type natriuretic peptide and troponin T were elevated. Transthoracic echocardiogram identified thickening of the biventricular walls, interatrial septum and atrioventricular valve leaflets. Global longitudinal strain was reduced with relative apical sparing, suspicious for cardiac amyloidosis. Technetium-99m and 3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy supported a diagnosis of transthyretin amyloidosis (ATTR). However, urinary Bence Jones protein (kappa) was identified despite a normal kappa/lambda light chain ratio and no serum paraprotein. Bone marrow and buccal biopsy provided histological confirmation of amyloid. The bone marrow had no evidence of plasma cell dyscrasia but positive TTR immunohistochemistry. The patient had a T60A genetic mutation for hereditary ATTR. Overlapping cardiac and autonomic symptoms prompt an amyloid workup, which then must distinguish AL amyloid from ATTR pathology.

A description of variant transthyretin amyloidosis (ATTRv) stage 1 patients and asymptomatic carriers in Spain: the EMPATIa study

BACKGROUND

Variant transthyretin amyloidosis (ATTRv) is a rare multisystemic disorder caused by mutations in the transthyretin (TTR) gene. The aim of the present work was to describe the clinical profile of asymptomatic carriers (AC) and Coutinho stage 1 ATTRv patients in Spain.

METHODS

National, multicentre, cross-sectional study that included 86 AC and 19 patients diagnosed in the previous 12 months to enrolment. Clinical and demographical data, TTR gene mutations, red flags anamnesis, neurological and cardiological assessments were collected.

RESULTS

The mean age of patients was 56.8 years at onset and 58.6 years at diagnosis; 53% of patients and 51% of AC were from non-endemic areas. Val50Met was the most frequent mutation in both groups. Neuropathy impairment score data (mean 17.7 ± 20.5) and small-fibre function in lower limbs assessed with SUDOSCAN revealed that patients were diagnosed at early stages of neurological impairment. Peripheral polyneuropathy (84.2%), autonomic neuropathy (73.7%), cardiac (63.2%) and gastrointestinal (47.4%) alterations were the most common symptoms in patients. Autonomic neuropathy, gastrointestinal impairment, carpal tunnel syndrome, cardiac and ocular alterations were potentially related to ATTRv in the AC group.

CONCLUSIONS

The EMPATIa study provides a detailed description of AC and Coutinho stage 1 ATTRv patients across Spain, confirming the multisystemic clinical profile of the disease. This study reveals a diagnosis delay around 1.8 years, highlighting the importance of a profound disease awareness to reach a diagnose in earlier stages of neurological impairment.

Transthyretin amyloid polyneuropathy in France: A cross-sectional study with 413 patients and real-world tafamidis meglumine use (2009-2019)

OBJECTIVE

We aimed to describe characteristics of patients with ATTR variant polyneuropathy (ATTRv-PN) and ATTRv-mixed and assess the real-world use and safety profile of tafamidis meglumine 20mg.

METHODS

Thirty-eight French hospitals were invited. Patient files were reviewed to identify clinical manifestations, diagnostic methods, and treatment compliance.

RESULTS

Four hundred and thirteen patients (296 ATTRv-PN, 117 ATTRv-mixed) were analyzed. Patients were predominantly male (68.0%) with a mean age of 57.2±17.2 years. Interval between first symptom(s) and diagnosis was 3.4±4.3 years. First symptoms included sensory complaints (85.9%), dysautonomia (38.5%), motor deficits (26.4%), carpal tunnel syndrome (31.5%), shortness of breath (13.3%), and unexplained weight loss (16.0%). Mini-invasive accessory salivary gland or punch skin and nerve biopsies were most common, with a performance of 78.8-100%. TTR genetic sequencing, performed in all patients, revealed 31 TTR variants. Tafamidis meglumine was initiated in 156/214 (72.9%) ATTRv-PN patients at an early disease stage. Median treatment duration was 6.00 years in ATTRv-PN and 3.42 years in ATTRv-mixed patients. Tafamidis was well tolerated, with 20 adverse events likely related to study drug among the 336 patients.

CONCLUSION

In France, ATTRv patients are usually identified early thanks to the national network and the help of diagnosis combining genetic testing and mini-invasive biopsies.

Patisiran, an RNAi therapeutic for hereditary transthyretin-mediated amyloidosis: Sub-analysis in Taiwanese patients from the APOLLO study

BACKGROUND

To examine the efficacy and safety of patisiran, an RNA interference therapeutic, in patients from Taiwan with hereditary transthyretin-mediated (hATTR) amyloidosis with polyneuropathy.

METHODS

The APOLLO phase 3 trial included patients from Taiwan who received patisiran 0.3 mg/kg intravenously or placebo once every 3 weeks (q3w) for 18 months (18 M), followed by patisiran 0.3 mg/kg q3w in an ongoing global open-label extension (OLE) study. The primary endpoint was change from baseline in modified Neuropathy Impairment Score +7 (mNIS+7) at 18 M.

RESULTS

Eighteen Taiwanese patients were enrolled in APOLLO (patisiran, n = 8; placebo, n = 10; all A97S gene variant) and 14 continued in the global OLE. In this Taiwanese sub-population, beneficial treatment effects at 18 M were observed in mNIS+7 (least squares mean difference in change from baseline [patisiran-placebo], -26.5 points; 95% confidence interval: -45.5, -7.5). Patients who switched from placebo to patisiran demonstrated slowing of polyneuropathy progression at month 12 in the global OLE, while those who received patisiran in APOLLO maintained the beneficial treatment effects. Patisiran had an acceptable safety profile in the Taiwanese sub-population.

CONCLUSION

This analysis suggests that patisiran is well tolerated and may provide a substantial clinical benefit for Taiwanese patients with hATTR amyloidosis with polyneuropathy.

TRIAL REGISTRATION INFORMATION

The studies were registered on the ClinicalTrials.gov. The APOLLO study ClinicalTrials.gov identifier is NCT01960348 (https://clinicaltrials.gov/ct2/show/NCT01960348), with the registration date of October 10, 2013, and the first patient was enrolled on December 13, 2013. For the global OLE, the ClinicalTrials.gov identifier is NCT02510261 (https://clinicaltrials.gov/ct2/show/NCT02510261) with the registration date of July 29, 2015, and the first patient was enrolled on July 13, 2015.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that treatment with patisiran is safe and efficacious in Taiwanese patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy.

Transthyretin monomers: a new plasma biomarker for pre-symptomatic transthyretin-related amyloidosis

BACKGROUND

Genotyping and amyloid fibril detection in tissues are generally considered the diagnostic gold standard in transthyretin-related amyloidosis. Patients carry less stable TTR homotetramers prone to dissociation into non-native monomers, which rapidly self-assemble into oligomers and, ultimately, amyloid fibrils. Thus, the initial event of the amyloid cascade produces the smallest transthyretin species: the monomers. This creates engineering opportunities for diagnosis that remain unexplored.

METHODS

We hypothesise that molecular sieving represents a promising method for isolating and concentrating trace TTR monomers from the tetramers present in plasma samples. Subsequently, immunodetection can be utilised to distinguish monomeric TTR from other low molecular weight proteins within the adsorbed fraction. A two-step assay was devised (ImmunoSieve assay), combining molecular sieving and immunodetection for sensing monomeric transthyretin. This assay was employed to analyse plasma microsamples from 10 individuals, including 5 pre-symptomatic carriers of TTR-V30M, the most prevalent amyloidosis-associated TTR variant worldwide, and 5 healthy controls.

RESULTS

The ImmunoSieve assay enable sensitive detection of monomeric transthyretin in plasma microsamples. Moreover, the circulating monomeric TTR levels were significantly higher in carriers of amyloidogenic TTR mutation.

CONCLUSIONS

Monomeric TTR can function as a biomarker for evaluating disease progression and assessing responses to therapies targeted at stabilising native TTR.

Longitudinal analysis of serum neurofilament light chain levels as marker for neuronal damage in hereditary transthyretin amyloidosis

OBJECTIVE

To evaluate serum neurofilament light chain (sNfL) as biomarker of disease onset, progression and treatment effect in hereditary transthyretin (ATTRv) amyloidosis patients and TTR variant (TTRv) carriers.

METHODS

sNfL levels were assessed longitudinally in persistently asymptomatic TTRv carriers (N = 12), persistently asymptomatic ATTRv amyloidosis patients (defined as asymptomatic patients but with amyloid detectable in subcutaneous abdominal fat tissue) (N = 8), in TTRv carriers who developed polyneuropathy (N = 7) and in ATTRv amyloidosis patients with polyneuropathy on treatment (TTR-stabiliser (N = 20) or TTR-silencer (N = 18)). Polyneuropathy was confirmed by nerve conduction studies or quantitative sensory testing. sNfL was analysed using a single-molecule array assay.

RESULTS

sNfL increased over 2 years in persistently asymptomatic ATTRv amyloidosis patients, but did not change in persistently asymptomatic TTRv carriers. In all TTRv carriers who developed polyneuropathy, sNfL increased from 8.4 to 49.8 pg/mL before the onset of symptoms and before polyneuropathy could be confirmed neurophysiologically. In symptomatic ATTRv amyloidosis patients on a TTR-stabiliser, sNfL remained stable over 2 years. In patients on a TTR-silencer, sNfL decreased after 1 year of treatment.

CONCLUSION

sNfL is a biomarker of early neuronal damage in ATTRv amyloidosis already before the onset of polyneuropathy. Current data support the use of sNfL in screening asymptomatic TTRv carriers and in monitoring of disease progression and treatment effect.

Identification and management of gastrointestinal manifestations of hereditary transthyretin amyloidosis: Recommendations from an Italian group of experts

Gastrointestinal manifestations are common across all hereditary transthyretin amyloidosis (ATTRv) genotypes. However, they are poorly specific, and their recognition as part of ATTRv is difficult, resulting in misdiagnosis with more common conditions. Moreover, delays in diagnosis occur because of fragmented knowledge, a shortage of centers of excellence and specialists dedicated to ATTRv management, and the scarce involvement of gastroenterologists in multidisciplinary teams. A group of Italian gastroenterologists with experience in the management of ATTRv took part in a project aimed at assessing the awareness of ATTRv among the community of Italian gastroenterologists through an online survey and providing education about practical aspects of ATTRv management. Survey results reported low participation, and very few patients with ATTRv were cared for by gastroenterologists. This highlights the need for greater attention to rare diseases in gastroenterology and emphasizes increasing awareness of ATTRv and diagnostic suspicion. Based on the experts' recommendations, a diagnosis of ATTRv should be suspected when at least one of the 'red flags' is detected. Subsequently, it is suggested to promptly ask for genetic testing and exclude a serum and urinary monoclonal protein, even before the detection of amyloid in biopsy samples, particularly in non-endemic areas.

Neurosurgical Intervention for Nerve and Muscle Biopsies

(1) Background: Neurologic and musculoskeletal diseases represent a considerable portion of the underlying etiologies responsible for the widely prevalent symptoms of pain, weakness, numbness, and paresthesia. Because of the subjective and often nonspecific nature of these symptoms, different diagnostic modalities have been explored and utilized. (2) Methods: Literature review. (3) Results: Nerve and muscle biopsy remains the gold standard for diagnosing many of the responsible neurological and musculoskeletal conditions. However, the need for invasive tissue sampling is diminishing as more investigations explore alternative diagnostic modalities. Because of this, it is important to explore the current role of neurosurgical intervention for nerve and muscle biopsies and its current relevance in the diagnostic landscape of neurological and musculoskeletal disorders. With consideration of the role of nerve and muscle biopsy, it is also important to explore innovations and emerging techniques for conducting these procedures. This review explores the indications and emerging techniques for neurological intervention for nerve and muscle biopsies. (4) Conclusions: The role of neurosurgical intervention for nerve and muscle biopsy remains relevant in diagnosing many neurological and musculoskeletal disorders. Biopsy is especially relevant as a supportive point of evidence for diagnosis in atypical cases. Additionally, emerging techniques have been explored to guide diagnostics and biopsy, conduct less invasive biopsies, and reduce risks of worsening neurologic function and other symptoms secondary to biopsy.

Neurofilament Light Chains in Systemic Amyloidosis: A Systematic Review

Peripheral and autonomic neuropathy are common disease manifestations in systemic amyloidosis. The neurofilament light chain (NfL), a neuron-specific biomarker, is released into the blood and cerebrospinal fluid after neuronal damage. There is a need for an early and sensitive blood biomarker for polyneuropathy, and this systematic review provides an overview on the value of NfL in the early detection of neuropathy, central nervous system involvement, the monitoring of neuropathy progression, and treatment effects in systemic amyloidosis. A literature search in PubMed, Embase, and Web of Science was performed on 14 February 2024 for studies investigating NfL levels in patients with systemic amyloidosis and transthyretin gene-variant (TTRv) carriers. Only studies containing original data were included. Included were thirteen full-text articles and five abstracts describing 1604 participants: 298 controls and 1306 TTRv carriers or patients with or without polyneuropathy. Patients with polyneuropathy demonstrated higher NfL levels compared to healthy controls and asymptomatic carriers. Disease onset was marked by rising NfL levels. Following the initiation of transthyretin gene-silencer treatment, NfL levels decreased and remained stable over an extended period. NfL is not an outcome biomarker, but an early and sensitive disease-process biomarker for neuropathy in systemic amyloidosis. Therefore, NfL has the potential to be used for the early detection of neuropathy, monitoring treatment effects, and monitoring disease progression in patients with systemic amyloidosis.

Diagnosis and treatment of hereditary transthyretin amyloidosis with polyneuropathy in the United States: Recommendations from a panel of experts

Hereditary transthyretin (ATTRv; v for variant) amyloidosis is a rare, multisystem, progressive, and fatal disease in which polyneuropathy is a cardinal manifestation. Due to a lack of United States (US)-specific guidance on ATTRv amyloidosis with polyneuropathy, a panel of US-based expert clinicians convened to address identification, monitoring, and treatment of this disease. ATTRv amyloidosis with polyneuropathy should be suspected in unexplained progressive neuropathy, especially if associated with systemic symptoms or family history. The diagnosis is confirmed through genetic testing, biopsy, or cardiac technetium-based scintigraphy. Treatment should be initiated as soon as possible after diagnosis, with gene-silencing therapeutics recommended as a first-line option. Consensus is lacking on what represents "disease progression" during treatment; however, the aggressive natural history of this disease should be considered when evaluating the effectiveness of any therapy.

Treatment response and neurofilament light chain levels with long-term patisiran in hereditary transthyretin-mediated amyloidosis with polyneuropathy: 24-month results of an open-label extension study

BACKGROUND

Longitudinal changes in neurofilament light chain (NfL) levels were evaluated alongside prespecified clinical assessments 24 months into the patisiran Global open-label extension (OLE) study in patients with ATTRv amyloidosis with polyneuropathy.

METHODS

All patients enrolled in the Global OLE, from phase III APOLLO and phase II OLE parent studies, received patisiran. Assessments included measures of polyneuropathy (modified Neuropathy Impairment Score+7 (mNIS+7)), quality of life (QOL; Norfolk QOL-Diabetic Neuropathy questionnaire (Norfolk QOL-DN)), and plasma NfL.

RESULTS

Patients receiving patisiran in the parent study (APOLLO-patisiran, n = 137; phase II OLE-patisiran, n = 25) demonstrated sustained improvements in mNIS+7 (mean change from parent study baseline (95% confidence interval): APOLLO-patisiran -4.8 (-8.9, -0.6); phase II OLE-patisiran -5.8 (-10.5, -1.2)) and Norfolk QOL-DN (APOLLO-patisiran -2.4 (-7.2, 2.3)), and maintained reduced NfL levels at Global OLE 24 months. After initiating patisiran in the Global OLE, APOLLO-placebo patients (n = 49) demonstrated stabilized mNIS+7, improved Norfolk QOL-DN, and significantly reduced NfL levels. Patisiran continued to demonstrate an acceptable safety profile. Earlier patisiran initiation was associated with a lower exposure-adjusted mortality rate.

CONCLUSIONS

Long-term patisiran treatment led to sustained improvements in neuropathy and QOL, with NfL demonstrating potential as a biomarker for disease progression and treatment response in ATTRv amyloidosis with polyneuropathy.

Current barriers and recommendations on the diagnosis of transthyretin amyloid cardiomyopathy: a Delphi study

Objectives

This study has been conducted to investigate the non-invasive diagnostic journey of patients with a transthyretin amyloid cardiomyopathy (aTTR-CM) in Turkey, identify the challenges and uncertainties encountered on the path to diagnosis from the perspectives of expert physicians, and develop recommendations that can be applied in such cases.

Methods

This study employed a three-round modified Delphi method and included 10 cardiologists and five nuclear medicine specialists. Two hematologists also shared their expert opinions on the survey results related to hematological tests during a final face-to-face discussion. A consensus was reached when 80% or more of the panel members marked the "agree/strongly agree" or "disagree/strongly disagree" option.

Results

The panelists unanimously agreed that the aTTR-CM diagnosis could be established through scintigraphy (using either 99mTc-PYP, 99mTc-DPD, or 99mTc-HMPD) in a patient with suspected cardiac amyloidosis (CA) without a further investigation if AL amyloidosis is ruled out (by sFLC, SPIE and UPIE). In addition, scintigraphy imaging performed by SPECT or SPECT-CT should reveal a myocardial uptake of Grade ≥2 with a heart-to-contralateral (H/CL) ratio of ≥1.5. The cardiology panelists recommended using cardiovascular magnetic resonance (CMR) and a detailed echocardiographic scoring as a last resort before considering an endomyocardial biopsy in patients with suspected CA whose scintigraphy results were discordant/inconclusive or negative but still carried a high clinical suspicion of aTTR-CM.

Conclusion

The diagnostic approach for aTTR-CM should be customized based on the availability of diagnostic tools/methods in each expert clinic to achieve a timely and definitive diagnosis.

Biomarkers of axonal damage to favor early diagnosis in variant transthyretin amyloidosis (A-ATTRv)

Early identification of ATTRv amyloidosis disease onset is still often delayed due to the lack of validated biomarkers of this disease. Light chain neurofilament (NfL) have shown promising results in early diagnosis in this disease, but data is still needed, including with alternative measuring methods. Our aim was to study the levels of NfL measured by ELISA. Furthermore, interstitial matrix metalloproteinase type 1 (MMP-1) serum levels were measured as a potential new biomarker in ATTRv. Serum NfL and MMP-1 were measured using ELISA assays in 90 participants (29 ATTR-V30M patients, 31 asymptomatic V30M-TTR variant carriers and 30 healthy controls). Median NfL levels among ATTRv amyloidosis patients were significantly higher (116 pg/mL vs 0 pg/mL in both comparison groups). The AUC comparing ATTRv amyloidosis patients and asymptomatic carriers was 0.90 and the NfL concentration of 93.55 pg/mL yielded a sensitivity of 79% and a specificity of 87%. NfL levels had a significant positive correlation with NIS values among patients. We found a negative significant correlation between eGFR and NfL levels. Finally, MMP1 levels were not different between groups. Evidence of NfL use for early diagnosis of ATTR-PN amyloidosis is growing. ELISA seems a reliable and available technique for it quantification. Decreased GFR could influence NfL plasma levels.

Nerve pathology of microangiopathy and thromboinflammation in hereditary transthyretin amyloidosis

OBJECTIVE

Despite amyloid deposition as a hallmark of hereditary transthyretin amyloidosis (ATTRv) with polyneuropathy, this pathology could not completely account for nerve degeneration. ATTRv patients frequently have vasomotor symptoms, but microangiopathy hypothesis in ATTRv was not systemically clarified.

METHODS

This study examined the vascular pathology of sural nerves in ATTRv patients with transthyretin (TTR) mutation of p.Ala117Ser (TTR-A97S), focusing on morphometry and patterns of molecular expression in relation to nerve degeneration. We further applied human microvascular endothelial cell (HMEC-1) culture to examine the direct effect of TTR-A97S protein on endothelial cells.

RESULTS

In ATTRv nerves, there was characteristic microangiopathy compared to controls: increased vessel wall thickness and decreased luminal area; both were correlated with the reduction of myelinated fiber density. Among the components of vascular wall, the area of collagen IV in ATTRv nerves was larger than that of controls. This finding was validated in a cell model of HMEC-1 culture in which the expression of collagen IV was upregulated after exposure to TTR-A97S. Apoptosis contributed to the endothelial cell degeneration of microvasculatures in ATTRv endoneurium. ATTRv showed prothrombotic status with intravascular fibrin deposition, which was correlated with (1) increased tissue factor and coagulation factor XIIIA and (2) reduced tissue plasminogen activator. This cascade led to intravascular thrombin deposition, which was colocalized with upregulated p-selectin and thrombomodulin, accompanied by complement deposition and macrophages infiltration, indicating thromboinflammation in ATTRv.

INTERPRETATION

Microangiopathy with thromboinflammation is characteristic of advanced-stage ATTRv nerves, which provides an add-on mechanism and therapeutic target for nerve degeneration.

[Difficulties in differential diagnosis of the AL- and ATTR-cardiac amyloidosis. Case report]

The article presents a clinical case describing a complex differential diagnosis of cardiac amyloidosis types and verification of the diagnosis of AL-amyloidosis.

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.

Quantification of muscle involvement in familial amyloid polyneuropathy using MRI

BACKGROUND AND PURPOSE

Transthyretin familial amyloid polyneuropathy (TTR-FAP) is a rare genetic disease with autosomal-dominant inheritance. In this study, we aimed to quantify fatty infiltration (fat fraction [FF]) and magnetization transfer ratio (MTR) in individual muscles of patients with symptomatic and asymptomatic TTR-FAP using magnetic resonance imaging. Secondarily, we aimed to assess correlations with clinical and electrophysiological variables.

METHODS

A total of 39 patients with a confirmed mutation in the TTR gene (25 symptomatic and 14 asymptomatic) and 14 healthy volunteers were included. A total of 16 muscles were manually delineated in the nondominant lower limb from T1-weighted anatomical images. The corresponding masks were propagated on the MTR and FF maps. Detailed neurological and electrophysiological examinations were conducted in each group.

RESULTS

The MTR was decreased (42.6 AU; p = 0.001) and FF was elevated (14%; p = 0.003) in the lower limbs of the symptomatic group, with preferential posterior and lateral involvement. In the asymptomatic group, elevated FF was quantified in the gastrocnemius lateralis muscle (11%; p = 0.021). FF was significantly correlated with disease duration (r = 0.49, p = 0.015), neuropathy impairment score for the lower limb (r = 0.42, p = 0.041), Overall Neuropathy Limitations Scale score (r = 0.49, p = 0.013), polyneuropathy disability score (r = 0.57, p = 0.03) and the sum of compound muscle action potential (r = 0.52, p = 0.009). MTR was strongly correlated to FF (r = 0.78, p < 0.0001), and a few muscles with an FF within the normal range had a reduced MTR.

CONCLUSION

These observations suggest that FF and MTR could be interesting biomarkers in TTR-FAP. In asymptomatic patients, FF in the gastrocnemius lateralis muscle could be a good indicator of the transition from an asymptomatic to a symptomatic form of the disease. MTR could be an early biomarker of muscle alterations.

Vutrisiran: A Review in Polyneuropathy of Hereditary Transthyretin-Mediated Amyloidosis

Silencing the transthyretin (TTR) gene is an effective strategy in the treatment of hereditary transthyretin-mediated (hATTR) amyloidosis. Vutrisiran (Amvuttra®), an RNA interference (RNAi) therapeutic targeting TTR mRNA, is approved in the USA and EU for the treatment of adults with polyneuropathy of hATTR amyloidosis. N-acetylgalactosamine conjugation and enhanced stabilisation chemistry are utilised to target vutrisiran to the liver and increase stability, respectively, allowing for subcutaneous administration once every 3 months. In a pivotal phase 3 study in patients with hATTR amyloidosis with polyneuropathy, subcutaneous vutrisiran 25 mg every 3 months significantly reduced neuropathy impairment versus external placebo. Vutrisiran was also associated with significant improvements in neuropathy-specific quality of life, gait speed, nutritional status and disability scores. Vutrisiran was generally well tolerated; the only common adverse events to occur at a greater incidence than with external placebo were pain in extremity and arthralgia. Vutrisiran reduces serum vitamin A levels and vitamin A supplementation is recommended. In conclusion, vutrisiran is an efficacious and generally well-tolerated alternative option for the treatment of polyneuropathy of hATTR amyloidosis, which has the potential advantage of infrequent subcutaneous dosage.

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.

Comparison between tafamidis and liver transplantation as first-line therapy for hereditary transthyretin amyloidosis

BACKGROUND

By stabilizing transthyretin, tafamidis delays progression of amyloidosis due to transthyretin variant (ATTRv) and replaced liver transplantation (LT) as the first-line therapy. No study compared these two therapeutic strategies.

METHODS

In a monocentric retrospective cohort analysis, patients with ATTRv amyloidosis treated with either tafamidis or LT were compared using a propensity score and a competing risk analysis for three endpoints: all-cause mortality, cardiac worsening (heart failure or cardiovascular death) and neurological worsening (worsening in PolyNeuropathy Disability score).

RESULTS

345 patients treated with tafamidis (n = 129) or LT (n = 216) were analyzed, and 144 patients were matched (72 patients in each group, median age 54 years, 60% carrying the V30M mutation, 81% of stage I, 69% with cardiac involvement, median follow-up: 68 months). Patients treated with tafamidis had longer survival than LT patients (HR: 0.35; p = .032). Conversely, they also presented a 3.0-fold higher risk of cardiac worsening and a 7.1-fold higher risk of neurological worsening (p = .0071 and p < .0001 respectively).

CONCLUSIONS

ATTRv amyloidosis patients treated with tafamidis would present a better survival but also a faster deterioration of their cardiac and neurological statuses as compared with LT. Further studies are needed to clarify the therapeutic strategy in ATTRv amyloidosis.

Pediatric vascular anomalies in Austria. Where are we at? A survey among primary care pediatricians

Introduction

Vascular anomalies (VAs) are rare conditions and affected patients often experience a difficult patient journey. Timely diagnosis is only possible if primary caregivers are aware of the anomalies and are connected with dedicated specialists. Aim of our survey was to investigate the knowledge about diagnostic and therapeutic possibilities for children with VAs, and the existing networking among primary pediatric caregivers in Austria.

Methods

Primary care pediatricians in Austria were invited to complete an online questionnaire consisting of 28 questions focusing on pediatric VAs.

Results

Out of 373 invited pediatricians 93 (25%) returned the questionnaires, 86 of which were complete. Most physicians (39/93 42%) answered that they see between 15 and 30 patients with infantile hemangiomas per year. Vascular malformations are rarely treated in the primary care setting; most primary care pediatricians (58/86, 67%) reported that they currently treat fewer than 5 patients with such type of VAs. There was unequivocal agreement among the participants (84/86, 98%) on the need to establish a network of specialists and a registry dedicated to pediatric VAs.

Conclusions

This survey represents the first study shedding light on the awareness of VAs among Austrian pediatricians and can serve as a basis for future investigations and advances in the management of these conditions in Austria and other countries with a similar healthcare setting.

Corneal confocal microscopy identifies corneal nerve loss and increased Langerhans cells in presymptomatic carriers and patients with hereditary transthyretin amyloidosis

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is a rare, but life-threatening protein misfolding disorder due to TTR gene mutations. Cardiomyopathy (ATTRv-CM) and polyneuropathy (ATTRv-PN) with early small nerve fibre involvement are the most common manifestations. Timely diagnosis and treatment initiation are key to limiting progression of disease. Corneal confocal microscopy (CCM) is a non-invasive method to quantify corneal small nerve fibres and immune cell infiltrates in vivo.

METHODS

This cross-sectional study investigated the utility of CCM in 20 patients with ATTRv amyloidosis (ATTRv-CM, n = 6; ATTRv-PN, n = 14) and presymptomatic carriers (n = 5) compared to 20 age- and sex-matched healthy controls. Corneal nerve fibre density, corneal nerve fibre length, corneal nerve branch density, and cell infiltrates were assessed.

RESULTS

Corneal nerve fibre density and nerve fibre length were significantly lower in patients with ATTRv amyloidosis compared to healthy controls regardless of the clinical phenotype (ATTRv-CM, ATTRv-PN) and corneal nerve fibre density was significantly lower in presymptomatic carriers. Immune cell infiltrates were only evident in patients with ATTRv amyloidosis, which correlated with reduced corneal nerve fibre density.

CONCLUSIONS

CCM identifies small nerve fibre damage in presymptomatic carriers and symptomatic patients with ATTRv amyloidosis and may serve as a predictive surrogate marker to identify individuals at risk of developing symptomatic amyloidosis. Furthermore, increased corneal cell infiltration suggests an immune-mediated mechanism in the pathogenesis of amyloid neuropathy.

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.

Efficacy and safety of vutrisiran for patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy: a randomized clinical trial

BACKGROUND

The study objective was to assess the effect of vutrisiran, an RNA interference therapeutic that reduces transthyretin (TTR) production, in patients with hereditary transthyretin (ATTRv) amyloidosis with polyneuropathy.

METHODS

HELIOS-A was a phase 3, global, open-label study comparing the efficacy and safety of vutrisiran with an external placebo group (APOLLO study). Patients were randomized 3:1 to subcutaneous vutrisiran 25 mg every 3 months (Q3M) or intravenous patisiran 0.3 mg/kg every 3 weeks (Q3W) for 18 months.

RESULTS

HELIOS-A enrolled 164 patients (vutrisiran, n = 122; patisiran reference group, n = 42); external placebo, n = 77. Vutrisiran met the primary endpoint of change from baseline in modified Neuropathy Impairment Score +7 (mNIS+7) at 9 months (p = 3.54 × 10^-12), and all secondary efficacy endpoints; significant improvements versus external placebo were observed in Norfolk Quality of Life-Diabetic Neuropathy, 10-meter walk test (both at 9 and 18 months), mNIS+7, modified body-mass index, and Rasch-built Overall Disability Scale (all at 18 months). TTR reduction with vutrisiran Q3M was non-inferior to within-study patisiran Q3W. Most adverse events were mild or moderate in severity, and consistent with ATTRv amyloidosis natural history. There were no drug-related discontinuations or deaths.

CONCLUSIONS

Vutrisiran significantly improved multiple disease-relevant outcomes for ATTRv amyloidosis versus external placebo, with an acceptable safety profile.

CLINICALTRIALS.GOV

NCT03759379.

Updated Evaluation of the Safety, Efficacy and Tolerability of Tafamidis in the Treatment of Hereditary Transthyretin Amyloid Polyneuropathy

Hereditary amyloid transthyretin (ATTRv) amyloidosis is a devastating hereditary multisystemic disease affecting predominantly the peripheral and autonomic nervous systems and the heart. ATTRv is caused by mutations in the transthyretin (TTR) gene, leading to extracellular deposition of amyloid fibrils in multiple organs including the peripheral nervous system. If untreated, it is associated with a fatal outcome 10-12 years after disease onset. Different treatments are available for patients with ATTRv polyneuropathy. Tafamidis 20 mg is approved in Europe since 2011 for early stages of ATTRv polyneuropathy (stage I - able to walk without support) and it is recommended as first-line therapy in these patients. Tafamidis is a TTR stabilizer that selectively binds to TTR and kinetically stabilizes both wild-type native TTR and mutant TTR. Consequently, it has the potential to prevent the amyloidogenic cascade initiated by TTR tetramer dissociation into its monomers and subsequent misfolding and aggregation. Tafamidis is an oral drug, taken once per day, with proved efficacy, safety and tolerability in ATTRv-PN patients as demonstrated in different clinical trials and open-label extension studies as well in clinical practice setting with around 10 years of experience. Tafamidis treatment started in the earliest stages of the disease is associated with better neurological outcomes. A multidisciplinary approach in referral centres is also fundamental for monitoring patients to assess individual response to treatment.

Ser77Tyr transthyretin amyloidosis in Israel: Initial manifestations and diagnostic features

OBJECTIVE

Amyloidosis due to the transthyretin Ser77Tyr mutation (ATTRS77Y) is a rare autosomal-dominant disorder, characterized by carpal-tunnel syndrome, poly- and autonomic-neuropathy, and cardiomyopathy. However, related symptoms and signs are often nonspecific and confirmatory tests are required. We describe the age and frequency of early symptoms and diagnostic features among individuals of Jewish Yemenite descent in Israel.

METHODS

Records of mutation carriers were retrospectively reviewed. ATTRS77Y diagnosis was defined by the presence of amyloid in tissue and/or amyloid-related cardiomyopathy.

RESULTS

We identified the Ser77Tyr mutation at the heterozygous state in 19 amyloidosis patients (mean age at diagnosis: 62 ± 5.7 years, range 49-70) and 30 amyloid-negative carriers. The probability for disease diagnosis increased from 4.4% at age 49 to 100% at 70 and occurred earlier in males. Initial symptoms preceded diagnosis by 5 ± 3.8 years (range 0-12) and were commonly sensory changes in the extremities. Erectile dysfunction predated these in 8/13 (62%) males. In two patients cardiac preceded neurological symptoms. Two patients declined symptoms. Electrophysiological studies near the time of diagnosis indicated a median neuropathy at the wrist in 18/19 (95%) and polyneuropathy in 13/19 (68%). Skin biopsy revealed epidermal denervation in 15/16 (94%) patients. Cardiomyopathy was identified in 16/19 (84%). Sensory complaints or epidermal denervations were present in 17/30 (57%) of amyloid-negative carriers and co-occurred in 10/30 (33%).

INTERPRETATION

ATTRS77Y symptoms commonly occur after age 50, but may begin earlier. Median neuropathy, skin denervation and cardiomyopathy are frequently identified. Symptoms may be absent in patients and common in amyloid-negative carriers.

Implications of Extra-cardiac Disease in Patient Selection for Heart Transplantation: Considerations in Cardiac Amyloidosis

Disease-modifying therapies in both light chain and transthyretin amyloidosis have improved patient functional status and survival. Conceivably, as heart failure may progress despite amyloid therapies, more patients may be considered for heart transplantation. In earlier eras, extra-cardiac amyloid deposits significantly reduced post-heart transplant patient survival and functional status compared to the non-amyloid population. In the modern era, transplant centres have reported improved outcomes in amyloidosis as patient selection has grown more stringent. Importantly, systematic candidate evaluation should assess the degree of extra-cardiac involvement, the effectiveness of disease-modifying therapies and downstream effects on patients' nutrition and frailty. This review outlines such an overall approach while also considering that organ-specific selection criteria may vary between individual transplant centres. A methodical approach to patient evaluation will promote better understanding of the prevalence and severity of extra-cardiac disease in amyloidosis patients referred for heart transplantation and of any disparities in decision outcomes in this population.

Prevalence estimation of ATTRv in China based on genetic databases

Introduction: Amyloid transthyretin (ATTR) is divided into either hereditary (ATTRv) or sporadic (ATTRwt) and ATTRv is a rare hereditary disease transmitted as an autosomal dominant manner. Its global prevalence is traditionally estimated as 5,000 to 10,000 persons. However, it may be underestimated and the exact prevalence of ATTRv in China mainland remains unknown. Methods: The Genome Aggregation database (gnomAD) database (containing 125,748 exomes) and two genomic sequencing databases--China Metabolic Analytics Project (ChinaMAP) (containing 10588 individuals) and Amcarelab gene database (containing 45392 exomes), were integrated to estimate the prevalence of ATTRv in the world and mainland Chinese populations. Pathogenic variants allele frequency and the prevalence of ATTRv was calculated. Results: Six variants, counting 470 alleles, were defined as pathogenic variants in gnomAD. The prevalence of ATTRv in the world population was 57.4/100,000. Two variants (2 allele counts) and 15 variants (34 individuals) were defined as pathogenic variants in the ChinaMAP database and the Amcarelab exome database, respectively. Thus, the estimated prevalence interval of ATTRv in mainland China was 18.9/100,000-74,9/100,000. Conclusion: The present study demonstrated that the previous prevalence was greatly underestimated using traditional methods. Therefore, raising awareness of the disease is essential for recognizing ATTRv in its early stage.

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.

Current approaches to the diagnosis and management of amyloidosis

Amyloidosis is a collection of diseases caused by the misfolding of proteins that aggregate into insoluble amyloid fibrils and deposit in tissues. While these fibrils may aggregate to form insignificant localised deposits, they can also accumulate in multiple organs to the extent that amyloidosis can be an immediately life-threatening disease, requiring urgent treatment. Recent advances in diagnostic techniques and therapies are dramatically changing the disease landscape and patient prognosis. Delays in diagnosis and treatment remain the greatest challenge, necessitating physician awareness of the common clinical presentations that suggest amyloidosis. The most common types are transthyretin (ATTR) amyloidosis followed by immunoglobulin light-chain (AL) amyloidosis. While systemic AL amyloidosis was previously considered a death sentence with no effective therapies, significant improvement in patient survival has occurred over the past 2 decades, driven by greater understanding of the disease process, risk-adapted adoption of myeloma therapies such as proteosome inhibitors (bortezomib) and monoclonal antibodies (daratumumab) and improved supportive care. ATTR amyloidosis is an underdiagnosed cause of heart failure. Technetium scintigraphy has made noninvasive diagnosis much easier, and ATTR is now recognised as the most common type of amyloidosis because of the increased identification of age-related ATTR. There are emerging ATTR treatments that slow disease progression, decrease patient hospitalisations and improve patient quality of life and survival. This review aims to update physicians on recent developments in amyloidosis diagnosis and management and to provide a diagnostic and treatment framework to improve the management of patients with all forms of amyloidosis.

Three Newly Recognized Likely Pathogenic Gene Variants Associated with Hereditary Transthyretin Amyloidosis

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTRv [variant]) is a clinically heterogeneous, progressively debilitating, fatal disease resulting from the deposition of insoluble amyloid fibrils in various organs and tissues. Early diagnosis of ATTRv can be facilitated with genetic testing; however, such testing of the TTR gene identifies variants of uncertain significance (VUS) in a minority of cases, a small percentage of which have the potential to be pathogenic. The Akcea/Ambry VUS Initiative is dedicated to gathering molecular, clinical, and inheritance data for each TTR VUS identified by genetic testing programs to reclassify TTR variants to a clinically actionable status (e.g., variant likely pathogenic [VLP]) where appropriate.

METHODS

Classification criteria used here, based on recommendations from the American College of Medical Genetics and Genomics, are stringent and comprehensive, requiring distinct lines of evidence supporting pathogenesis.

RESULTS

Three TTR variants have been reclassified from VUS to VLP, including c.194C>T (p.A65V), c.172G>C (p.D58H), and c.239C>T (p.T80I). In each case, the totality of genetic, structural, and clinical evidence provided strong support for pathogenicity.

CONCLUSIONS

Based on several lines of evidence, three TTR VUS were reclassified as VLP, resulting in a high likelihood of disease diagnosis for those and subsequent patients as well as at-risk family members.

Hereditary transthyretin amyloidosis in Sweden: Comparisons between a non-endemic and an endemic region

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTRv) is endemic in northern Sweden (Västerbotten). The awareness of ATTRv amyloidosis is lower in Stockholm, a non-endemic region in Sweden. The aim of this study was to compare the possible differences in diagnostic delay, disease phenotypes, treatment and survival between a non-endemic and an endemic region in Sweden.

METHODS

The in- and outpatient diagnosis registry at the Department of Neurology at Karolinska University Hospital and the Amyloidosis Centre at University Hospital of Umeå were used to identify patients between January 2006 and November 2017.

RESULTS

In total, 21 patients in Stockholm and 134 patients in Västerbotten were included. The time between symptom onset to time-point of diagnosis was significantly longer in Stockholm vs Västerbotten. This corresponded to a longer median time between first visit at amyloidosis centre to time-point of diagnosis in Stockholm vs in Västerbotten. The most common reason for a diagnostic delay was negative tissue biopsies.

CONCLUSION

There was a diagnostic-, but no patient-delay in non-endemic Stockholm vs endemic Västerbotten. Despite a more severe neuropathic phenotype in Stockholm at the onset, the systemic affection over the course of disease and of survival seems not to be influenced by the diagnosis delay in Stockholm.

Nerve Conduction Studies of Dorsal Sural Nerve: Normative Data and Its Potential Application in ATTRv Pre-Symptomatic Subjects

The objective of the study is to provide age-related normative values for dorsal sural nerve (DSN) and to analyse its application during follow-up of hereditary transthyretin amyloidosis (ATTRv) pre-symptomatic subjects. We consecutively recruited ATTRv pre-symptomatic carriers in which clinical examination, cardiological evaluation, and nerve conduction studies of the sural nerve and DSN were performed. To provide normative data of DSN, neurophysiologic parameters from healthy controls referred to our service were entered into linear regression analyses to check the relative influence of age and height. A correction grid was then derived. We collected 231 healthy subjects: the mean DSN sensory nerve action potential (SNAP) amplitude was 9.99 ± 5.48 μV; the mean conduction velocity was 49.01 ± 5.31 m/s. Significant correlations were found between age and height with DSN SNAP amplitude. Fifteen ATTRv pre-symptomatic carriers were examined. Sural nerve NCS were normal in 12/15 and revealed low/borderline values in three subjects. Considering our correction grid, we found an abnormal DNS amplitude in 9/15 subjects and low/borderline values in 2/15. In ATTRv, early detection of peripheral nerve damage is crucial to start a disease-modifying treatment. DSN may be easily and reliably included in the routine neurophysiological follow-up of ATTRv pre-symptomatic subjects.

Long-term efficacy and safety of inotersen for hereditary transthyretin amyloidosis: NEURO-TTR open-label extension 3-year update

Background

Hereditary transthyretin amyloidosis (hATTR/ATTRv) results from the deposition of misfolded transthyretin (TTR) throughout the body, including peripheral nerves. Inotersen, an antisense oligonucleotide inhibitor of hepatic TTR production, demonstrated a favorable efficacy and safety profile in patients with the polyneuropathy associated with hATTR in the NEURO-TTR (NCT01737398) study. We report longer-term efficacy and safety data for inotersen, with a median treatment exposure of 3 years.

Methods

Patients who satisfactorily completed NEURO-TTR were enrolled in its open-label extension (OLE) study. Efficacy assessments included the modified Neuropathy Impairment Score + 7 (mNIS + 7), Norfolk Quality of Life–Diabetic Neuropathy (Norfolk QoL-DN) questionnaire total score, and the Short Form 36 (SF-36v2) Health Survey Physical Component Summary score. Safety and tolerability were also assessed. Efficacy is reported for patients living in Europe and North America (this cohort completed the study approximately 9 months before the remaining group of patients outside these regions); safety is reported for the full safety dataset, comprising patients living in Europe, North America, and Latin America/Australasia. This study is registered with ClinicalTrials.gov, identifier NCT02175004.

Results

In the Europe and North America cohort of the NEURO-TTR study, 113/141 patients (80.1%) completed the study, and 109 patients participated in the OLE study. A total of 70 patients continued to receive inotersen (inotersen–inotersen) and 39 switched from placebo to inotersen (placebo–inotersen). The placebo–inotersen group demonstrated sustained improvement in neurological disease progression as measured by mNIS + 7, compared with predicted worsening based on projection of the NEURO-TTR placebo data (estimated natural history). The inotersen–inotersen group demonstrated sustained benefit, as measured by mNIS + 7, Norfolk QoL-DN, and SF-36v2, compared with estimated natural history as well as compared with the placebo–inotersen group. With a maximum exposure of 6.2 years, inotersen was not associated with any additional safety concerns or increased toxicity in the OLE study. Platelet and renal monitoring were effective in reducing the risk of severe adverse events in the OLE study.

Conclusion

Inotersen treatment for > 3 years slowed progression of the polyneuropathy associated with hATTR, and no new safety signals were observed.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11276-8.

Gait Characterization and Analysis of Hereditary Amyloidosis Associated with Transthyretin Patients: A Case Series

Hereditary amyloidosis associated with transthyretin (ATTRv), is a rare autosomal dominant disease characterized by length-dependent symmetric polyneuropathy that has gait impairment as one of its consequences. The gait pattern of V30M ATTRv amyloidosis patients has been described as similar to that of diabetic neuropathy, associated with steppage, but has never been quantitatively characterized. In this study we aim to characterize the gait pattern of patients with V30M ATTRv amyloidosis, thus providing information for a better understanding and potential for supporting diagnosis and disease progression evaluation. We present a case series in which we conducted two gait analyses, 18 months apart, of five V30M ATTRv amyloidosis patients using a 12-camera, marker based, optical system as well as six force platforms. Linear kinematics, ground reaction forces, and angular kinematics results are analyzed for all patients. All patients, except one, showed a delayed toe-off in the second assessment, as well as excessive pelvic rotation, hip extension and external transverse rotation and knee flexion (in stance and swing phases), along with reduced vertical and mediolateral ground reaction forces. The described gait anomalies are not clinically quantified; thus, gait analysis may contribute to the assessment of possible disease progression along with the clinical evaluation.

[Gene therapy options for hereditary transthyretin-related amyloidosis]

Hereditary transthyretin-related amyloidosis (ATTRv) is a rare autosomal dominant disease and is fatal if left untreated. It is caused by mutations in the transthyretin gene. All known mutations induce misfolding of the tetrameric transthyretin molecule and protein deposits in multiple organs. In peripheral nerves this result in sensorimotor and autonomic polyneuropathy and in cardiac muscle it causes cardiomyopathy. Untreated ATTRv is characterized by an irreversible and progressive course and death 7-11 years after symptom onset. Treatment options consist of TTR stabilizing drugs, such as tafamidis and active agents that selectively interfere at the mRNA level, the so-called gene silencers patisiran and inotersen. All forms of treatment aim to prevent amyloid tissue deposition in tissues and organ dysfunction. Patisiran works by RNA interference on endogenous mechanisms of gene expression. It results in the cleavage of TTR-mRNA using the cytoplasmatic RNA-induced silencing complex. Inotersen, an antisense oligonucleotide, degrades TTR-mRNA via activation of nuclear RNase H. Both mechanisms result in a significant reduction of TTR protein serum levels. The efficacy could be demonstrated by slowing or improving neuropathy progression in the phase III study APOLLO (patisiran) or the NEURO-TTR study (inotersen). Furthermore, the use of both agents led to an improvement in the quality of life in patients with ATTRv. Both forms of treatment are approved in Germany since August 2018 for polyneuropathy stages 1 and 2 according to Coutinho. The choice of treatment should be carried out individually considering drug formulation, contraindications and the necessary safety monitoring controls.