Selection of hereditary transthyretin amyloid patients for liver transplantation: the Swedish experience

Epidemiology of hereditary transthyretin amyloidosis in the northernmost region of Sweden: a retrospective cohort study

INTRODUCTION

Epidemiological data on hereditary transthyretin (ATTRv) amyloidosis from the northernmost region of Sweden (Norrbotten) are sparse.

METHODS

We reviewed the medical records of all incident cases of ATTRv amyloidosis in Norrbotten between 2006 and 2018. Official population and mortality statistics were used to estimate incidence rates and standardised mortality ratios (SMRs).

RESULTS

Ninety-three patients were diagnosed with ATTRv amyloidosis between 2006 and 2018 (median age, 72.8 years; 68.8% men; 95.7% Val30Met [p.Val50Met] mutation). The incidence rate per 100,000 persons and year increased from 1.50 (95% confidence interval [CI], 0.84-2.47) cases in 2006-2009 to 4.92 (95%CI, 3.46-6.78) cases in 2016-2018. The SMR in the ATTRv amyloidosis cohort was 2.64 times higher than in the general population in 2006-2018 (95%CI, 1.78-3.77). However, there were indications of lower SMRs over time (2006-2012, 2.96 [95%CI, 1.73-4.74]; 2013-2018, 2.32 [95%CI, 1.23-3.96]) and by use of disease-modifying drugs (no, 3.21 [95%CI, 1.87-5.13]; yes, 2.09 [95%CI, 1.08-3.64]).

CONCLUSION

The incidence of ATTRv amyloidosis increased 3-fold in Norrbotten between 2006 and 2018, most likely due to a previous underdiagnosis - with suggestions of lowered mortality during later years, possibly due to the introduction of disease-modifying drugs.

Evaluating Prognostic Factors for Liver Transplantation Among United States Patients With Hereditary Transthyretin-Mediated (hATTR) Amyloidosis Using National Registry Data

INTRODUCTION

Orthotopic liver transplantation has been used as a treatment for hereditary transthyretin-mediated (hATTR) amyloidosis, a rare, progressive, and multisystem disease.

RESEARCH QUESTION

The objective is to evaluate survival outcomes post-liver transplantation in patients with hATTR amyloidosis in the United States and assess whether previously published prognostic factors of patient survival in hATTR amyloidosis are generalizable to the US population.

DESIGN

This cohort study examined patients with hATTR amyloidosis undergoing liver transplant in the United States (N = 168) between March 2002 and March 2016 using data reported to the Organ Procurement and Transplantation Network (UNOS)/United Network for Organ Sharing (OPTN).

RESULTS

A multivariable Cox hazards regression model showed among all factors tested, only modified body mass index (kg/m² × g/L) at the time of transplant was significantly associated with survival. Higher modified BMI was associated with lower risk of death relative to a reference population (<600) with historically poor post-transplant outcomes. Patients with modified BMI 1000 to <1200 (hazard ratio [HR] = 0.27; 95% confidence interval [CI] = 0.10-0.73), 1200 to <1400 (HR = 0.20; 95% CI = 0.06-0.75), and ≥1400 (HR = 0.15; 95% CI = 0.04-0.61) exhibited improved adjusted 5-year post-transplant survival of 74%, 80%, and 85%, respectively, versus 33% in the reference population.

DISCUSSION

The association between a higher modified BMI threshold at the time of transplant and improved post-transplant survival suggests that the previously published patient selection criterion for modified BMI may not be applicable to the US population.

Impact of genotype and phenotype on cardiac biomarkers in patients with transthyretin amyloidosis - Report from the Transthyretin Amyloidosis Outcome Survey (THAOS)

Aim

Cardiac troponins and natriuretic peptides are established for risk stratification in light-chain amyloidosis. Data on cardiac biomarkers in transthyretin amyloidosis (ATTR) are lacking.

Methods and results

Patients (n = 1617) with any of the following cardiac biomarkers, BNP (n = 1079), NT-proBNP (n = 550), troponin T (n = 274), and troponin I (n = 108), available at baseline in the Transthyretin Amyloidosis Outcomes Survey (THAOS) were analyzed for differences between genotypes and phenotypes and their association with survival. Median level of BNP was 68.0 pg/mL (IQR 30.5–194.9), NT-proBNP 337.9 pg/mL (IQR 73.0–2584.0), troponin T 0.03 μg/L (IQR 0.01–0.05), and troponin I 0.08 μg/L (IQR 0.04–0.13). NT-proBNP and BNP were higher in wild-type than mutant-type ATTR, troponin T and I did not differ, respectively. Non-Val30Met patients had higher BNP, NT-proBNP and troponin T levels than Val30Met patients, but not troponin I. Late-onset Val30Met was associated with higher levels of troponin I and troponin T compared with early-onset. 115 patients died during a median follow-up of 1.2 years. Mortality increased with increasing quartiles (BNP/NT-proBNP Q1 = 1.7%, Q2 = 5.2%, Q3 = 21.7%, Q4 = 71.3%; troponin T/I Q1 = 6.5%, Q2 = 14.5%, Q3 = 33.9%, Q4 = 45.2%). Three-year overall-survival estimates for BNP/NT-proBNP and troponin T/I quartiles differed significantly (p<0.001). Stepwise risk stratification was achieved by combining NT-proBNP/BNP and troponin T/I. From Cox proportional hazards model, age, modified body mass index, mutation (Val30Met vs. Non-Val30Met) and BNP/NT-proBNP (Q1–Q3 pooled vs. Q4) were identified as independent predictors of survival in patients with mutant-type ATTR.

Conclusions

In this ATTR patient cohort, cardiac biomarkers were abnormal in a substantial percentage of patients irrespective of genotype. Along with age, mBMI, and mutation (Val30Met vs. Non-Val30Met), cardiac biomarkers were associated with surrogates of disease severity with BNP/NT-proBNP identified as an independent predictor of survival in ATTR.

Trial registration

ClinicalTrials.gov NCT00628745

Peripheral Blood Cell Gene Expression Diagnostic for Identifying Symptomatic Transthyretin Amyloidosis Patients: Male and Female Specific Signatures

Background: Early diagnosis of familial transthyretin (TTR) amyloid diseases remains challenging because of variable disease penetrance. Currently, patients must have an amyloid positive tissue biopsy to be eligible for disease-modifying therapies. Endomyocardial biopsies are typically amyloid positive when cardiomyopathy is suspected, but this disease manifestation is generally diagnosed late. Early diagnosis is often difficult because patients exhibit apparent symptoms of polyneuropathy, but have a negative amyloid biopsy. Thus, there is a pressing need for an additional early diagnostic strategy for TTR-aggregation-associated polyneuropathy and cardiomyopathy.

Methods and Findings: Global peripheral blood cell mRNA expression profiles from 263 tafamidis-treated and untreated V30M Familiar Amyloid Neuropathy patients, asymptomatic V30M carriers, and healthy, age- and sex-matched controls without TTR mutations were used to differentiate symptomatic from asymptomatic patients. We demonstrate that blood cell gene expression patterns reveal sex-independent, as well as male- and female-specific inflammatory signatures in symptomatic FAP patients, but not in asymptomatic carriers. These signatures differentiated symptomatic patients from asymptomatic V30M carriers with >80% accuracy. There was a global downregulation of the eIF2 pathway and its associated genes in all symptomatic FAP patients. We also demonstrated that the molecular scores based on these signatures significantly trended toward normalized values in an independent cohort of 46 FAP patients after only 3 months of tafamidis treatment.

Conclusions: This study identifies novel molecular signatures that differentiate symptomatic FAP patients from asymptomatic V30M carriers as well as affected males and females. We envision using this approach, initially in parallel with amyloid biopsies, to identify individuals who are asymptomatic gene carriers that may convert to FAP patients. Upon further validation, peripheral blood cell mRNA expression profiling could become an independent early diagnostic. This quantitative gene expression signature for symptomatic FAP could also become a biomarker to demonstrate significant disease-modifying effects of drugs and drug candidates. For example, when new disease modifiers are being evaluated in a FAP clinical trial, such surrogate biomarkers have the potential to provide an objective, quantitative and mechanistic molecular diagnostic of disease response to therapy.

Outcome in patients treated with isolated liver transplantation for familial transthyretin amyloidosis to prevent cardiomyopathy

BACKGROUND

Familial transthyretin (TTR) amyloidosis is caused by different TTR mutations resulting in different clinical phenotypes of the disease. The Leu111Met mutation causes severe restrictive cardiomyopathy. Liver transplantation (LTx) is an established treatment option for patients with TTR amyloidosis; however, information on outcome after isolated LTx in patients with Leu111Met mutation amyloidosis is limited.

METHODS

Between 2005 and 2012, six patients with TTR Leu111Met amyloidosis underwent isolated orthotopic LTx. None suffered from neuropathy. Prior to LTx, patients presented with echocardiographic manifestations of early cardiac amyloid involvement and in five endomyocardial biopsy was positive for TTR amyloid.

RESULTS

Median age at LTx was 45.5 yr (range 39-54), and four were male (67%). All patients were alive at a median follow-up of 56.6 months (range 18-104). No surgical complications occurred. Two patients (33%) underwent cardiac transplantation during follow-up due to progressive cardiomyopathy. The remaining four patients experienced no echocardiographic or clinical deterioration of cardiac function following LTx.

CONCLUSION

Isolated LTx appears to be a valuable treatment option for patients with familial TTR amyloidosis due to Leu111Met mutation. Appropriate timing of LTx is of utmost importance to avoid development of severe amyloid cardiomyopathy and the need for combined heart and liver transplantation.

Outcome of gastric emptying and gastrointestinal symptoms after liver transplantation for hereditary transthyretin amyloidosis

Background

Hereditary transthyretin amyloid (ATTR) amyloidosis is a rare but fatal autosomal dominant condition that is present all over the world. A liver transplantation has been shown to halt the progress of the disease in selected patients and is currently considered to be the standard treatment. Gastrointestinal manifestations are common in hereditary ATTR amyloidosis and are important for the patients’ morbidity and mortality. The aim of this study was to evaluate the long-term outcome of gastric emptying, gastrointestinal symptoms and nutritional status after liver transplantation for the disease.

Methods

Swedish patients with hereditary ATTR amyloidosis transplanted between 1990 and 2012 were included. A standardized method for measuring gastric emptying with a Tc^99m-labelled meal followed by scintigraphy was utilized. Validated questionnaires were used to assess gastrointestinal symptoms and the modified body mass index (mBMI), in which BMI is multiplied by s-albumin, was used to evaluate nutritional status. Non-parametrical statistical tests were used.

Results

Gastric emptying rates and nutritional statuses were evaluated approximately eight months before and two and five years after liver transplantation, whereas gastrointestinal symptoms were assessed in median nine months before and two and nine years after transplantation. No significant change was found in gastric emptying (median half-time 137 vs. 132 vs. 125 min, p = 0.52) or nutritional status (median mBMI 975 vs. 991 vs. 973, p = 0.75) after transplantation. Gastrointestinal symptom scores, however, had increased significantly over time (median score 7 vs. 10 vs. 13, p < 0.01).

Conclusions

Gastric emptying and nutritional status were maintained after liver transplantation for hereditary ATTR amyloidosis, although gastrointestinal symptom scores had increased over time.

Electronic supplementary material

The online version of this article (doi:10.1186/s12876-015-0284-4) contains supplementary material, which is available to authorized users.

Liver transplantation in transthyretin amyloidosis: issues and challenges

Hereditary transthyretin amyloidosis (ATTR) is a rare worldwide autosomal dominant disease caused by the systemic deposition of an amyloidogenic variant of transthyretin (TTR), which is usually derived from a single amino acid substitution in the TTR gene. More than 100 mutations have been described, with V30M being the most prevalent. Each variant has a different involvement, although peripheral neuropathy and cardiomyopathy are the most common. Orthotopic liver transplantation (OLT) was implemented as the inaugural disease-modifying therapy because the liver produces the circulating unstable TTR. In this review, we focus on the results and long-term outcomes of OLT for ATTR after more than 2063 procedures and 23 years of experience. After successful OLT, neuropathy and organ impairment are not usually reversed, and in some cases, the disease progresses. The overall 5-year survival rate is approximately 100% for V30M patients and 59% for non-ATTR V30M patients. Cardiac-related death and septicemia are the main causes of mortality. Lower survival is related to malnutrition, a longer duration of disease, cardiomyopathy, and a later onset (particularly for males). Deposits, which are composed of a mixture of truncated and full-length TTR (type A) fibrils, have been associated with posttransplant myocardial dysfunction. A higher incidence of early hepatic artery thrombosis of the graft has also been documented for these patients. Liver-kidney/heart transplantation is an alternative for patients with advanced renal disease or heart failure. The sequential procedure, in which ATTR livers are reused in patients with liver disease, reveals that neuropathy in the recipient may appear as soon as 6 years after OLT, and ATTR deposits may appear even earlier. Long-term results of trials with amyloid protein stabilizers or disrupters, silencing RNA, and antisense oligonucleotides will highlight the value and limitations of liver transplantation.

Gene expression profile in hereditary transthyretin amyloidosis: differences in targeted and source organs

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTR) is a genetic disease caused by a point mutation in the TTR gene that causes the liver to produce an unstable TTR protein. The most effective treatment has been liver transplantation in order to replace the variant TTR producing liver with one that produces only wild-type TTR. ATTR amyloidosis patients' livers are reused for liver sick patients, i.e. the Domino procedure. However, recent findings have demonstrated that ATTR amyloidosis can develop in the recipients within 7-8 years. The aim of this study was to elucidate how the genetic profile of the liver is affected by the disease, and how amyloid deposits affect target tissue.

METHODS

Gene expression analysis was used to unravel the genetic profiles of Swedish ATTR V30M patients and controls. Biopsies from adipose tissue and liver were examined.

RESULTS AND CONCLUSIONS

ATTR amyloid patients' gene expression profile of the main source organ, the liver, differed markedly from that of the controls, whereas the target organs' gene expression profiles were not markedly altered in the ATTR amyloid patients compared to those of the controls. An impaired ER/protein folding pathway might suggest ER overload due to mutated TTR protein.

Noninvasive risk stratification of patients with transthyretin amyloidosis

OBJECTIVES

We sought to evaluate noninvasive parameters by electrocardiography, echocardiography, technetium-99m-3,3-diphosphono-1,2-propanodicarboxylic acid ((99m)Tc-DPD) scintigraphy, and cardiac magnetic resonance for the prediction of all-cause mortality in patients with cardiac transthyretin amyloidosis (ATTR).

BACKGROUND

ATTR may present with highly variable symptoms, including polyneuropathy and cardiomyopathy, the latter being associated with a poor outcome. However, data on noninvasive risk stratification of ATTR are limited.

METHODS

A total of 70 patients with ATTR were evaluated by echocardiography, cardiac biomarkers, and (99m)Tc-DPD scintigraphy. Cardiac magnetic resonance was performed in 30 patients. Echocardiographic findings and plasma levels of biomarkers were correlated with results of quantitative analysis of scintigraphy using a region-of-interest technique (whole-body as well as heart tracer retention). Receiver-operating characteristic (ROC) analysis was performed to calculate a cutoff value of (99m)Tc-DPD scintigraphy for heart retention for the diagnosis of cardiac amyloid involvement with the highest sensitivity and specificity. Univariate and multivariate analyses were performed in patients with cardiac involvement (n = 60) to determine noninvasive predictors of all-cause mortality.

RESULTS

Scintigraphy findings correlated with morphological (interventricular septum thickness, left ventricular hypertrophy index) as well as functional (mitral annular systolic velocity, mitral/tricuspid annular plane systolic excursion) findings, cardiac biomarkers, renal function, and late gadolinium enhancement. The ROC-derived cutoff for the detection of cardiac amyloidosis by scintigraphic heart tracer retention was 4.8%. Univariate Cox regression revealed N-terminal pro-B-type natriuretic peptide, troponin T, mitral annular plane systolic excursion, and left ventricular hypertrophy index as predictors of all-cause mortality. However, on multivariate analysis, troponin T remained the only independent predictor of survival. The ROC-derived cutoff value of troponin T predicting all-cause mortality with the highest sensitivity (80.0%) and specificity (68.7%) was 0.0375 ng/l.

CONCLUSIONS

Quantitative analysis of tracer retention is capable of characterizing the severity of cardiac involvement in ATTR. By multivariate analysis, troponin T remained the only independent predictor of survival.

Diagnostic hallmarks and pitfalls in late-onset progressive transthyretin-related amyloid-neuropathy

Familial amyloid polyneuropathy (FAP) is a progressive systemic autosomal dominant disease caused by pathogenic mutations in the transthyretin (TTR) gene. We studied clinical, electrophysiological, histopathological, and genetic characteristics in 15 (13 late-onset and two early-onset) patients belonging to 14 families with polyneuropathy and mutations in TTR. In comparison, we analysed the features of nine unrelated patients with an idiopathic polyneuropathy, in whom TTR mutations have been excluded. Disease occurrence was familial in 36 % of the patients with TTR-associated polyneuropathy and the late-onset type was observed in 86 % (mean age at onset 65.5 years). Clinically, all late-onset TTR-mutant patients presented with distal weakness, pansensory loss, absence of deep tendon reflexes, and sensorimotor hand involvement. Afferent-ataxic gait was present in 92 % leading to wheelchair dependence in 60 % after a mean duration of 4.6 years. Autonomic involvement was observed in 60 %, and ankle edema in 92 %. The sensorimotor polyneuropathy was from an axonal type in 82 %, demyelinating or mixed type in 9 % each. Compared to the TTR-unmutated idiopathic polyneuropathy patients, we identified rapid progression, early ambulatory loss, and autonomic disturbances, associated with a severe polyneuropathy as red flags for TTR-FAP. In 18 % of the late-onset TTR-FAP patients, no amyloid was found in nerve biopsies. Further diagnostic pitfalls were unspecific electrophysiology, and coincident diabetes mellitus (23 %) or monoclonal gammopathy (7 %). We conclude that a rapid disease course, severely ataxic gait, hand involvement, and autonomic dysfunction are diagnostic hallmarks of late-onset TTR-FAP. Genetic analysis should be performed even when amyloid deposits are lacking or when polyneuropathy-causing comorbidities are concomitant.

The Transthyretin Amyloidosis Outcomes Survey (THAOS) registry: design and methodology

Abstract Background: Transthyretin (TTR) amyloidosis - the most common type of hereditary amyloidosis - also has an acquired form and is observed in geographically dispersed populations. TTR amyloidosis is marked by considerable clinical heterogeneity, and the main phenotypes are neurologic and cardiovascular.

METHODS

THAOS is an international, noninterventional, longitudinal, observational registry designed to evaluate overall survival in patients, better understand genotype-phenotype relationships and the natural history of TTR amyloidosis, and evaluate the effects of liver transplantation and other treatments on disease progression in TTR amyloidosis. All individuals with a confirmed TTR mutation with or without a diagnosis of TTR amyloidosis and patients with wild-type TTR amyloidosis are eligible to be enrolled in the registry.

PURPOSE

To describe the design and methodology of the recently established registry. Procedures for data collection are outlined and a minimum set of assessments for the standard evaluation of all subjects with TTR amyloidosis is described. Demographic information, TTR genotype, medical history, family history of the disease, and transplant history are assessed at baseline. On return visits, signs and symptoms of the disease are evaluated, general examinations are conducted, and laboratory data, measures of neurologic and cardiovascular function, and quality of life are assessed according to the standard of care for patients. Visits on at least a biannual basis are recommended. The registry will remain open for a period of at least 10 years.

RESULTS

The initial experience suggests that the registry is characterized by a comprehensive set of data elements which can be completed by providers from the various clinical backgrounds who administer care to individuals with TTR amyloidosis.

CONCLUSION

As of September 2011, 30 centers in 15 of the 19 countries participating in the THAOS registry have enrolled 975 patients. Such data provide a representative sample of the global TTR amyloidosis patient population, including asymptomatic TTR variant carriers, which can inform the natural history of the disease and offer the potential to evaluate novel therapeutic modalities in diverse patient subpopulations.