TRANSTHYRETIN AMYLOIDOSIS THERAPIES: GUIDING THE FUTURE

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

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

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

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Population Pharmacokinetic-Pharmacodynamic Model of Serum Transthyretin Following Patisiran Administration

Hereditary transthyretin-mediated amyloidosis is an inherited, rapidly progressive, life-threatening disease caused by mutated transthyretin (TTR) protein. Patisiran is a small interfering RNA (siRNA) formulated in a lipid nanoparticle that inhibits hepatic TTR protein synthesis by RNA interference. We have developed an indirect-response pharmacokinetic-pharmacodynamic model relating plasma siRNA (ALN-18328) levels to serum TTR reduction across five clinical studies. A sigmoidal function described this relationship, with estimated Hill coefficient of 0.548, and half maximal inhibitory concentration (IC₅₀), IC₈₀, and IC₉₀ values of 9.45, 118.5, and 520.5 ng/mL, respectively. Following patisiran 0.3 mg/kg every 3 weeks (q3w), steady-state plasma ALN-18328 exposures were between IC₈₀ and IC₉₀, yielding average serum TTR reductions of 80%-90% from baseline. Covariate analysis indicated similar TTR reduction across evaluated intrinsic and extrinsic factors, obviating the need for dose adjustment. Modeling results support the recommended patisiran dosing schedule of 0.3 mg/kg q3w, with a maximum dose of 30 mg for patients weighing ≥100 kg.

Hereditary Transthyretin Amyloidosis: Clinical Presentation and Management Updates

Hereditary transthyretin amyloidosis, once a rare progressive neuropathy and/or cardiomyopathy, is now recognized with increasing worldwide frequency, various phenotypes, and over 130 gene mutations identified to date. This inherited disorder develops as a result of mutated transthyretin amyloid aggregation and systematic deposition throughout the body. With increasing knowledge about the pathophysiology of this disease, new disease-modifying therapies are being developed. In addition to slowing progression, these new agents were found to improve quality of life and reduce the severity of neuropathic symptoms. Two new gene-modifying therapies recently received Food and Drug Administration approval following the positive results from phase III trials. These include an antisense oligonucleotide, inotersen, and small interfering RNA, patisiran, which were reported to reduce the production of transthyretin and had promising safety profiles. Additional novel therapies are being explored with hopes to prolong survival. Therefore, early diagnosis of this treatable disorder has become increasingly important in clinical practice.

Amyloid Cardiomyopathy

Amyloid cardiomyopathy is emerging as an important and under-recognised cause of heart failure and cardiac arrhythmias, especially in older adults. This disorder is characterised by extracellular deposition of amyloid fibrils that form due to misfolding of secreted light chains (AL) or transthyretin protein (ATTR). In ATTR, amyloid aggregates typically result from excessive accumulation of wild-type transthyretin (ATTRwt) or from protein structural defects caused by TTR gene variants (ATTRv). Amyloid fibril deposition may predominantly affect the heart or show multi-system involvement. Previously considered to be rare and inexorably progressive with no specific therapy, there has been enormous recent interest in ATTR cardiomyopathy due to upwardly-revised estimates of disease prevalence together with development of disease-modifying interventions. Because of this, there is a clinical imperative to have a high index of suspicion to identify potential cases and to be aware of contemporary diagnostic methods and treatment options. Genetic testing should be offered to all patients with proven ATTR to access the benefits of new therapies specific to ATTRv and allow predictive testing of family members. With heightened awareness of amyloid cardiomyopathy and expanded use of genetic testing, a substantial rise in the numbers of asymptomatic individuals who are carriers of pathogenic variants is expected, and optimal strategies for monitoring and treatment of these individuals at risk need to be determined. Pre-emptive administration of fibril-modifying therapies provides an unprecedented opportunity for disease prevention and promises to change amyloid cardiomyopathy from being a fatal to a treatable disorder.

[Problems of diagnostics and treatment of transtiretinum amyloidosis with destruction of the heart in the elderly: Clinical experience.]

The article presents a modern understanding of the treatment of cardiac amyloidosis, provides data on the frequency of occurrence, classification and variants of clinical manifestations of transthyretin amyloidosis. This pathology is a slowly progressive disease, the symptoms of which usually appear in the elderly and senile age. This diagnosis may become more common in the future as the population ages and diagnostic methods improve. As an illustration, a description of the clinical case of transtritin amyloidosis of the heart in a 77-year-old patient, which occurred with a primary lesion of the heart and symptoms of chronic heart failure, is given. It shows the difficulties in the lifetime diagnosis of transthyretin amyloidosis.

Inotersen Treatment for Patients with Hereditary Transthyretin Amyloidosis

BACKGROUND

Hereditary transthyretin amyloidosis is caused by pathogenic single-nucleotide variants in the gene encoding transthyretin ( TTR) that induce transthyretin misfolding and systemic deposition of amyloid. Progressive amyloid accumulation leads to multiorgan dysfunction and death. Inotersen, a 2'- O-methoxyethyl-modified antisense oligonucleotide, inhibits hepatic production of transthyretin.

METHODS

We conducted an international, randomized, double-blind, placebo-controlled, 15-month, phase 3 trial of inotersen in adults with stage 1 (patient is ambulatory) or stage 2 (patient is ambulatory with assistance) hereditary transthyretin amyloidosis with polyneuropathy. Patients were randomly assigned, in a 2:1 ratio, to receive weekly subcutaneous injections of inotersen (300 mg) or placebo. The primary end points were the change in the modified Neuropathy Impairment Score+7 (mNIS+7; range, -22.3 to 346.3, with higher scores indicating poorer function; minimal clinically meaningful change, 2 points) and the change in the score on the patient-reported Norfolk Quality of Life-Diabetic Neuropathy (QOL-DN) questionnaire (range, -4 to 136, with higher scores indicating poorer quality of life). A decrease in scores indicated improvement.

RESULTS

A total of 172 patients (112 in the inotersen group and 60 in the placebo group) received at least one dose of a trial regimen, and 139 (81%) completed the intervention period. Both primary efficacy assessments favored inotersen: the difference in the least-squares mean change from baseline to week 66 between the two groups (inotersen minus placebo) was -19.7 points (95% confidence interval [CI], -26.4 to -13.0; P<0.001) for the mNIS+7 and -11.7 points (95% CI, -18.3 to -5.1; P<0.001) for the Norfolk QOL-DN score. These improvements were independent of disease stage, mutation type, or the presence of cardiomyopathy. There were five deaths in the inotersen group and none in the placebo group. The most frequent serious adverse events in the inotersen group were glomerulonephritis (in 3 patients [3%]) and thrombocytopenia (in 3 patients [3%]), with one death associated with one of the cases of grade 4 thrombocytopenia. Thereafter, all patients received enhanced monitoring.

CONCLUSIONS

Inotersen improved the course of neurologic disease and quality of life in patients with hereditary transthyretin amyloidosis. Thrombocytopenia and glomerulonephritis were managed with enhanced monitoring. (Funded by Ionis Pharmaceuticals; NEURO-TTR ClinicalTrials.gov number, NCT01737398 .).

Patisiran, an RNAi Therapeutic, for Hereditary Transthyretin Amyloidosis

BACKGROUND

Patisiran, an investigational RNA interference therapeutic agent, specifically inhibits hepatic synthesis of transthyretin.

METHODS

In this phase 3 trial, we randomly assigned patients with hereditary transthyretin amyloidosis with polyneuropathy, in a 2:1 ratio, to receive intravenous patisiran (0.3 mg per kilogram of body weight) or placebo once every 3 weeks. The primary end point was the change from baseline in the modified Neuropathy Impairment Score+7 (mNIS+7; range, 0 to 304, with higher scores indicating more impairment) at 18 months. Other assessments included the Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) questionnaire (range, -4 to 136, with higher scores indicating worse quality of life), 10-m walk test (with gait speed measured in meters per second), and modified body-mass index (modified BMI, defined as [weight in kilograms divided by square of height in meters]×albumin level in grams per liter; lower values indicated worse nutritional status).

RESULTS

A total of 225 patients underwent randomization (148 to the patisiran group and 77 to the placebo group). The mean (±SD) mNIS+7 at baseline was 80.9±41.5 in the patisiran group and 74.6±37.0 in the placebo group; the least-squares mean (±SE) change from baseline was -6.0±1.7 versus 28.0±2.6 (difference, -34.0 points; P<0.001) at 18 months. The mean (±SD) baseline Norfolk QOL-DN score was 59.6±28.2 in the patisiran group and 55.5±24.3 in the placebo group; the least-squares mean (±SE) change from baseline was -6.7±1.8 versus 14.4±2.7 (difference, -21.1 points; P<0.001) at 18 months. Patisiran also showed an effect on gait speed and modified BMI. At 18 months, the least-squares mean change from baseline in gait speed was 0.08±0.02 m per second with patisiran versus -0.24±0.04 m per second with placebo (difference, 0.31 m per second; P<0.001), and the least-squares mean change from baseline in the modified BMI was -3.7±9.6 versus -119.4±14.5 (difference, 115.7; P<0.001). Approximately 20% of the patients who received patisiran and 10% of those who received placebo had mild or moderate infusion-related reactions; the overall incidence and types of adverse events were similar in the two groups.

CONCLUSIONS

In this trial, patisiran improved multiple clinical manifestations of hereditary transthyretin amyloidosis. (Funded by Alnylam Pharmaceuticals; APOLLO ClinicalTrials.gov number, NCT01960348 .).

Cardiac amyloidosis: An update on pathophysiology, diagnosis, and treatment

The amyloidoses are a group of systemic diseases characterized by organ deposition of misfolded protein fragments of diverse origins. The natural history of the disease, involvement of other organs, and treatment options vary significantly based on the protein of origin. In AL amyloidosis, amyloid protein is derived from immunoglobulin light chains, and most often involves the kidneys and the heart. ATTR amyloidosis is categorized as mutant or wild-type depending on the genetic sequence of the transthyretin (TTR) protein produced by the liver. Wild-type ATTR amyloidosis mainly involves the heart, although the reported occurrence of bilateral carpal tunnel syndrome, spinal stenosis and biceps tendon rupture in these patients speaks to more generalized protein deposition. Mutant TTR is marked by cardiac and/or peripheral nervous system involvement. Cardiac involvement is associated with symptoms of heart failure, and dictates the clinical course of the disease. Cardiac amyloidosis can be diagnosed noninvasively by echocardiography, cardiac MRI, or nuclear scintigraphy. Endomyocardial biopsy may be needed in the case of equivocal imaging findings or discordant data. Treatment is aimed at relieving congestive symptoms and targeting the underlying amyloidogenic process. This includes anti-plasma cell therapy in AL amyloidosis, and stabilization of the TTR tetramer or inhibition of TTR protein production in ATTR amyloidosis. Cardiac transplantation can be considered in highly selected patients in tandem with therapy aimed at suppressing the amyloidogenic process, and appears associated with durable long-term survival.

Lipid Nanoparticle Systems for Enabling Gene Therapies

Genetic drugs such as small interfering RNA (siRNA), mRNA, or plasmid DNA provide potential gene therapies to treat most diseases by silencing pathological genes, expressing therapeutic proteins, or through gene-editing applications. In order for genetic drugs to be used clinically, however, sophisticated delivery systems are required. Lipid nanoparticle (LNP) systems are currently the lead non-viral delivery systems for enabling the clinical potential of genetic drugs. Application will be made to the Food and Drug Administration (FDA) in 2017 for approval of an LNP siRNA drug to treat transthyretin-induced amyloidosis, presently an untreatable disease. Here, we first review research leading to the development of LNP siRNA systems capable of silencing target genes in hepatocytes following systemic administration. Subsequently, progress made to extend LNP technology to mRNA and plasmids for protein replacement, vaccine, and gene-editing applications is summarized. Finally, we address current limitations of LNP technology as applied to genetic drugs and ways in which such limitations may be overcome. It is concluded that LNP technology, by virtue of robust and efficient formulation processes, as well as advantages in potency, payload, and design flexibility, will be a dominant non-viral technology to enable the enormous potential of gene therapy.

Transthyretin Cardiac Amyloidosis in Older Americans

Wild-type transthyretin cardiac amyloidosis (ATTRwt), formerly called senile cardiac amyloidosis (SCA), is almost exclusively a disorder of older adults. As the population ages, the diagnosis of ATTRwt will increase, making it the most common form of cardiac amyloidosis. An important precondition to reduce underdiagnosis and misdiagnosis is to maintain a high index of suspicion for cardiac amyloidosis. Several clues can be gleaned from the clinical history, physical exam, electrocardiography, and noninvasive imaging techniques. Nuclear scintigraphy agents using 99mTc-phosphate derivatives combined with assessment for monoclonal proteins are eliminating the need for tissue confirmation in ATTR. Morbidity and mortality from ATTRwt cardiac amyloid is high and the emergence of numerous therapies based on a biologic understanding of the pathophysiology of this condition, including drugs to inhibit the synthesis of TTR, stabilize TTR, and degrade or extract amyloid, provides new hope for those afflicted. This review briefly covers the epidemiology, pathophysiology, and clinical manifestations, as well as diagnostic strategies and treatment, of ATTR in older adults.

Involvement of Macrophages in the Pathogenesis of Familial Amyloid Polyneuropathy and Efficacy of Human iPS Cell-Derived Macrophages in Its Treatment

We hypothesized that tissue-resident macrophages in familial amyloid polyneuropathy (FAP) patients will exhibit qualitative or quantitative abnormalities, that may accelerate transthyretin (TTR)-derived amyloid deposition. To evaluate this, we examined the number and subset of tissue-resident macrophages in heart tissue from amyloid-deposited FAP and control patients. In both FAP and control patients, tissue-resident macrophages in heart tissue were all Iba⁺/CD163⁺/CD206⁺ macrophages. However, the number of macrophages was significantly decreased in FAP patients compared with control patients. Furthermore, the proportion of intracellular TTR in CD14⁺ monocytes was reduced in peripheral blood compared with healthy donors. Based on these results, we next examined degradation and endocytosis of TTR in human induced pluripotent stem (iPS) cell-derived myeloid lineage cells (MLs), which function like macrophages. iPS-MLs express CD163 and CD206, and belong to the inhibitory macrophage category. In addition, iPS-MLs degrade both native and aggregated TTR in a cell-dependent manner in vitro. Further, iPS-MLs endocytose aggregated, and especially polymerized, TTR. These results suggest that decreased tissue-localized macrophages disrupt clearance of TTR-derived amyloid deposits, leading to progression of a pathological condition in FAP patients. To improve this situation, clinical application of pluripotent stem cell-derived MLs may be useful as an approach for FAP therapy.

[Presentations of transthyretin associated familial amyloid polyneuropathy in Argentina]

Transthyretin-related familial amyloid polyneuropathy (TTR-FAP) is a hereditary disease with variable geographical distribution. The aim of this study was to present our experience with TTR-FAP patients. We retrospectively analyzed nine cases belonging to different families. Diagnostic criteria were based on the combination of compatible clinical picture, histopathological findings and genetic confirmation. Five cases showed the classic presentation and other 4 the late onset variant. The p.Val30Met mutation in the TTR gene was found in 6 cases and p.Ala36Pro, p.Thr60Ala and p.Tyr114Cys in the remaining 3, respectively. The median age of symptom onset was 35 years (26-60 range). Mean time to diagnosis was 4.2 ± 1.5 years. Our patient series showed the heterogeneity in clinical presentation of TTR-FAP in a non-endemic region of South America.

Evolving landscape in the management of transthyretin amyloidosis

Transthyretin (TTR) amyloidosis (ATTR amyloidosis) is a multisystemic, multigenotypic disease resulting from deposition of insoluble ATTR amyloid fibrils in various organs and tissues. Although considered rare, the prevalence of this serious disease is likely underestimated because symptoms can be non-specific and diagnosis largely relies on amyloid detection in tissue biopsies. Treatment is guided by which tissues/organs are involved, although therapeutic options are limited for patients with late-stage disease. Indeed, enthusiasm for liver transplantation for familial ATTR amyloidosis with polyneuropathy was dampened by poor outcomes among patients with significant neurological deficits or cardiac involvement. Hence, there remains an unmet medical need for new therapies. The TTR stabilizers tafamidis and diflunisal slow disease progression in some patients with ATTR amyloidosis with polyneuropathy, and the postulated synergistic effect of doxycycline and tauroursodeoxycholic acid on dissolution of amyloid is under investigation. Another therapeutic approach is to reduce production of the amyloidogenic protein, TTR. Plasma TTR concentration can be significantly reduced with ISIS-TTR(Rx), an investigational antisense oligonucleotide-based drug, or with patisiran and revusiran, which are investigational RNA interference-based therapeutics that target the liver. The evolving treatment landscape for ATTR amyloidosis brings hope for further improvements in clinical outcomes for patients with this debilitating disease.

Clinical features and outcomes of systemic amyloidosis with gastrointestinal involvement: a single-center experience

BACKGROUND/AIMS

The gastrointestinal (GI) tract often becomes involved in patients with systemic amyloidosis. As few GI amyloidosis data have been reported, we describe the clinical features and outcomes of patients with pathologically proven GI amyloidosis.

METHODS

We identified 155 patients diagnosed with systemic amyloidosis between April 1995 and April 2013. Twenty-four patients (15.5%) were diagnosed with GI amyloidosis using associated symptoms, and the diagnoses were confirmed by direct biopsy.

RESULTS

Among the 24 patients, 20 (83.3%) had amyloidosis light chain (AL), three (12.5%) had amyloid A, and one (4.2%) had transthyretin-related type amyloidosis. Their median age was 57 years (range, 37 to 72), and 10 patients were female (41.7%). The most common symptoms of GI amyloidosis were diarrhea (11 patients, 45.8%), followed by anorexia (nine patients, 37.5%), weight loss, and nausea and/or vomiting (seven patients, 29.2%). The histologically confirmed GI tract site in AL amyloidosis was the stomach in 11 patients (55.0%), the colon in nine (45.0%), the rectum in seven (35.0%), and the small bowel in one (5.0%). Patients with GI involvement had a greater frequency of organ involvement (p = 0.014). Median overall survival (OS) in patients with GI involvement was shorter (7.95 months; range, 0.3 to 40.54) than in those without GI involvement (15.84 months; range, 0.0 to 114.53; p = 0.069) in a univariate analysis. A multivariate analysis of prognostic factors for AL amyloidosis revealed that GI involvement was not a significant predictor of OS (p = 0.447).

CONCLUSIONS

The prognosis of patients with AL amyloidosis and GI involvement was poorer than those without GI involvement, and they presented with more organ involvement and more advanced disease than those without organ involvement.

[Transthyretin-related amyloidotic cardiomyopathy: looking for the etiological treatment]

Transthyretin (TTR)-related amyloidosis is a disease caused by the deposition of insoluble fibrils deriving from the misfolding of TTR, a protein mainly produced by the liver. In the hereditary form of the disease (ATTRm), protein misfolding is secondary to a mutation in the TTR gene. ATTRm can manifest with different phenotypes: mainly neurological, mainly cardiac, or mixed. In the senile form of the disease (wild-type TTR or SSA), the deposition of non-mutated TTR occurs and, clinically, cardiomyopathy is predominant. Cardiac amyloidosis is still an underdiagnosed disease and clinical heterogeneity makes the diagnosis challenging. Until recently, no specific pharmacological treatment was available, liver transplantation being the only therapeutic option aimed at slowing disease progression in ATTRm and treatment was based on symptom relief. This review focuses on the emerging pharmacological treatments for TTR-related amyloidosis targeting different steps of the amyloidogenic process (blocking hepatic TTR synthesis, TTR tetramer stabilization and promotion of TTR amyloid fibril clearance).

Safety and efficacy of RNAi therapy for transthyretin amyloidosis

BACKGROUND

Transthyretin amyloidosis is caused by the deposition of hepatocyte-derived transthyretin amyloid in peripheral nerves and the heart. A therapeutic approach mediated by RNA interference (RNAi) could reduce the production of transthyretin.

METHODS

We identified a potent antitransthyretin small interfering RNA, which was encapsulated in two distinct first- and second-generation formulations of lipid nanoparticles, generating ALN-TTR01 and ALN-TTR02, respectively. Each formulation was studied in a single-dose, placebo-controlled phase 1 trial to assess safety and effect on transthyretin levels. We first evaluated ALN-TTR01 (at doses of 0.01 to 1.0 mg per kilogram of body weight) in 32 patients with transthyretin amyloidosis and then evaluated ALN-TTR02 (at doses of 0.01 to 0.5 mg per kilogram) in 17 healthy volunteers.

RESULTS

Rapid, dose-dependent, and durable lowering of transthyretin levels was observed in the two trials. At a dose of 1.0 mg per kilogram, ALN-TTR01 suppressed transthyretin, with a mean reduction at day 7 of 38%, as compared with placebo (P=0.01); levels of mutant and nonmutant forms of transthyretin were lowered to a similar extent. For ALN-TTR02, the mean reductions in transthyretin levels at doses of 0.15 to 0.3 mg per kilogram ranged from 82.3 to 86.8%, with reductions of 56.6 to 67.1% at 28 days (P<0.001 for all comparisons). These reductions were shown to be RNAi-mediated. Mild-to-moderate infusion-related reactions occurred in 20.8% and 7.7% of participants receiving ALN-TTR01 and ALN-TTR02, respectively.

CONCLUSIONS

ALN-TTR01 and ALN-TTR02 suppressed the production of both mutant and nonmutant forms of transthyretin, establishing proof of concept for RNAi therapy targeting messenger RNA transcribed from a disease-causing gene. (Funded by Alnylam Pharmaceuticals; ClinicalTrials.gov numbers, NCT01148953 and NCT01559077.).

Reduced myocardial 123-iodine metaiodobenzylguanidine uptake: a prognostic marker in familial amyloid polyneuropathy

BACKGROUND

Transthyretin familial amyloid polyneuropathy is a hereditary form of amyloidosis characterized by sensorimotor and autonomic neuropathy, cardiac conduction defects, and infiltrative cardiomyopathy. Previous studies have suggested that myocardial sympathetic denervation assessed by 123-iodine metaiodobenzylguanidine (MIBG) imaging occurs early in disease progression. However, its prognostic significance was never evaluated. We aimed to study the long-term prognostic value of myocardial sympathetic denervation detected by MIBG imaging in transthyretin familial amyloid polyneuropathy.

METHODS AND RESULTS

A total of 143 individuals with V30M transthyretin mutation underwent Holter, ambulatory blood pressure monitoring, echocardiography, and MIBG imaging. Time to all-cause death was compared with late heart-to-mediastinum MIBG uptake ratio (H/M; either in relation to the estimated lower limit of normal [1.60] or as a continuous variable) using Cox proportional hazards regression. Multivariable analyses were performed to test the prognostic accuracy of clinical, neurological, and cardiovascular parameters. During a median follow-up of 5.5 years, 32 (22%) patients died. Five-year mortality rate was 42% for late H/M <1.60 and 7% for late H/M ≥1.60 (hazard ratio, 7.19; P<0.001). Late H/M was identified as an independent prognostic predictor. Fifty-three patients were submitted to liver transplantation. In comparison with neurophysiological score-matched controls, transplanted patients had lower long-term mortality (hazard ratio, 0.32; P=0.012). Patients with late H/M<1.60 were at higher risk of unfavorable outcome but seemed to have benefited from liver transplantation.

CONCLUSIONS

Cardiac sympathetic denervation as assessed by MIBG imaging is a useful prognostic marker in transthyretin familial amyloid polyneuropathy.

[Cerebral amyloid angiopathy with familial transthyretin-derived oculoleptomeningeal amyloidosis]

Cerebral amyloid angiopathy (CAA) is caused by the accumulation of amyloid fibrils on vascular walls and is a well-known cause of cerebral hemorrhages in the elderly. This disease manifests as recurrent or multiple simultaneous subcortical hematomas, occasionally leading to fatal hemorrhages. Additionally, it is noteworthy that CAA-related hemorrhages can develop in individuals aged around 50 years. Although a few different amyloid fibril proteins have been isolated from patients with CAA, the most common protein is Aβ, which is also the main component of senile plaques in Alzheimer's disease. Recent studies have suggested that corticosteroid therapy is effective for preventing the recurrence of CAA-related hemorrhages. Hereditary generalized amyloidosis usually manifests as familial amyloid polyneuropathy (FAP), showing severe involvement of peripheral somatic and autonomic nerves. Many variant forms of transthyretin (TTR) with a single amino acid substitution have been identified as causative amyloid precursor proteins in FAP. Moreover, a small number of TTR gene mutations causes a rare phenotype of systemic amyloidosis characterized by preferential deposition of TTR-derived amyloid proteins in the vitreous body in the eye, as well as the leptomeninges and subarachnoidal vessels in the central nervous system (CNS). This disorder is called familial oculoleptomeningeal or leptomeningeal amyloidosis and is characterized clinically by CNS symptoms, including progressive dementia, seizures, ataxia, spastic paresis, and stroke-like episodes. Since the variant forms of TTR in this amyloidosis are derived from the retinal epithelium or choroid plexus, liver transplantation-an effective treatment for FAP-is considered less effective for treating this rare form of TTR-related systemic amyloidosis.

Transthyretin familial amyloid polyneuropathy

TTR FAP is characterized by phenotypic and genotypic heterogeneity. The severity of polyneuropathy along with autonomic dysfunction and heart involvement makes it a life-threatening disease. This protein is mainly produced by the liver. Molecular genetic testing is essential in the diagnostic strategy. TTR-Val30Met is the most frequent substitution, resulting in a guanine to cytosine mutation in exon 2 of the gene. It is virtually the only variant detected in Portugal, Brazil, and Sweden. By contrast, as many as 30 different TTR variants are reported in Japan and in other European countries. A less severe phenotype with late onset has been reported. Diagnosis should be performed as early as possible since upcoming pharmacological therapeutic approaches are now available, in addition to liver transplantation.

Amyloid neuropathies

Peripheral neuropathy is a common complication of many of the systemic amyloidoses. Although the cause of neuropathy is not entirely clear, it is likely related to amyloid deposition within the nerve. This may lead to focal, multifocal, or diffuse neuropathies involving sensory, motor and/or autonomic fibers. The presenting symptoms depend on the distribution of nerves affected. One of the most common phenotypes is sensorimotor polyneuropathy, which is characterized by symptoms of neuropathic pain, numbness, and in advanced cases weakness. Symptoms begin in the feet and ultimately progress to the proximal legs and hands. The most common focal neuropathy is a median neuropathy at the wrist, clinically known as carpal tunnel syndrome. Carpal tunnel symptoms may include pain and sensory disturbances in the lateral palm and fingers; hand weakness may ensue if the focal neuropathy is severe. Autonomic neuropathy may affect a variety of organ systems such as the cardiovascular, gastrointestinal, and genitourinary systems. Symptoms may be non-specific making the diagnosis of autonomic neuropathy more difficult to identify. However, it is important to recognize and distinguish autonomic neuropathy from diseases of the end-organs themselves. This article reviews the inherited and acquired amyloidoses that affect the peripheral nervous system including familial amyloid polyneuropathy, and primary, secondary and senile amyloidosis. We emphasize the clinical presentation of the neurologic aspects of these diseases, physical examination findings, appropriate diagnostic evaluation, treatment and prognosis.

[Familial amyloid polyneuropathies: therapeutic issues]

Patients with familial amyloidpolyneuropathies (FAP) require multidisciplinary neurologic and cardiologic management, including specific treatments to control the progression of systemic amyloidogenesis, symptomatic treatment of peripheral and autonomic neuropathies, and management of severe organ involvement (heart, eyes, kidneys). The first-line specific treatment of choice for met30 TTR-FAP is liver transplantation (LT) which suppresses the main source of mutant TTR, halts the progression of neuropathy in 70% of cases, and doubles the median survival time. Dual kidney-liver or heart-liver transplantation may be appropriate for patients with severe renal or cardiac failure. Tafamidis (Vyndaqel(R), Pfizer), a novel stabilizer of tetrameric TTR, has shown short-term effectiveness in slowing the progression of peripheral neuropathy in very early stages of met30 TTR-FAP This drug should thus be proposed for stage 1 symptomatic polyneuropathy. Other innovative medicines (RNA interference, antisense oligonucleotides) have been developed to block hepatic production of both mutant and wildtype TTR (noxious in late-onset forms of NAH after age 50 years), and to remove amyloid deposits (monoclonal anti-SAP). Clinical trials should first include patients with late-onset FAP or non-met30 TTR-FAP who are less responsive to LT7 and patients in whom Vyndaqel(R) is ineffective or inappropriate. Initial and periodic cardiac assessment is necessary, as cardiac impairment is inevitable and largely responsible for mortality. Symptomatic treatment is crucial to improve these patients' quality of life. Familial screening for carriers of the TTR gene mutation and regular clinical examination are essential to detect disease onset and to start specific therapy in a timely manner.

Familial amyloidotic polyneuropathy and transthyretin

There has been much progress in our understanding of transthyretin (TTR)-related amyloidosis including familial amyloidotic polyneuropathy (FAP), senile systemic amyloidosis and its related disorders from many clinical and experimental aspects. FAP is an inherited severe systemic amyloidosis caused by mutated TTR, and characterized by amyloid deposition mainly in the peripheral nervous system and the heart. Liver transplantation is the only available treatment for the disease. FAP is now recognized not to be a rare disease, and to have many variations based on genetical and biochemical variations of TTR. This chapter covers the recent advances in the clinical and pathological aspects of, and therapeutic approaches to FAP, and the trend as to the molecular pathogenesis of TTR.

[Metabolic turn over of amyloid fibrils and post-treatment regression of amyloid deposits in systemic amyloidosis with polyneuropathy]

Systemic amyloidosis that includes familial transthyretin (TTR)-related amyloid polyneuropathy (FAP) and primary systemic immunoglobulin light chain (AL)-derived amyloidosis was long considered to be an incurable disease, but effective therapeutic approaches developed during 20 years ago: liver transplantation for FAP and high dose melphalan with autologous peripheral blood stem cell transplantation (Auto-PBSCT). Systemic amyloidosis is characterized by the presence of an amyloid precursor protein in serum and both treatments can cease the production of amyloid precursor proteins in serum. After transplantation the progression of FAP symptoms certainly stopped, and the patients who were in an early stage of the disease and underwent successful operation showed considerable improvement in their quality of life. Similar clinical recovery was seen in primary systemic AL amyloidosis patients with polyneuropathy after high dose melphalan with auto-PBSCT. Histopathological regression of amyloid deposits on aspirated abdominal fat tissues and/or gastroduodenal mucosa was demonstrated in the patients with long post-treatment courses, indicating that an amyloid precursor protein is dynamically turned over in the lesions with amyloid deposits.

Early diagnosis and management of patients with familial ATTR amyloidosis receiving livers from asymptomatic variant TTR carriers

The possibility of a patient with familial ATTR amyloidosis receiving a liver from an asymptomatic variant TTR carrier is remote [corrected].However, in 2008, it was reported that this unlikely event occurred in a patient in Portugal. We report our protocol for early diagnosis and management of this entity.

[Familial amyloid polyneuropathy]

Familial amyloid polyneuropathy (FAP), a fatal disorder inherited in an autosomal dominant fashion, is characterized by systemic accumulation of polymerized transthyretin (TTR) in the peripheral nerves and systemic organs. Polyneuropathy is often a major manifestation of FAP. Although FAP was considered to be an endemic disorder, the advanced biochemical and molecular genetic analyses have shown worldwide occurrence. More than 100 different points of single or double mutations, or a deletion in the TTR gene, have been reported, and several different phenotypes of FAP have been documented, even for the same mutation in the TTR gene. Liver transplantation, which stops the production of amyloidogenic TTR in blood and replaces it with normal TTR, has been considered as an acceptable treatment for FAP. However, continuous amyloid deposition can occur from wild-type (normal) TTR in some patients. Currently, research an the inhibition of amyloid deposition by small organic molecules that are hypothesized to affect the fibril-forming ability of TTR is underway.

Combined heart-liver transplantation with extended cardiopulmonary bypass

We report a case of combined heart and liver transplantation for familial amyloid polyneuropathy. This is the first such combined transplant performed in Asia, and differs from previously described cases, in that cardiopulmonary bypass was continued at partial flow during liver transplantation in our case. This was done in order to provide haemodynamic support to the cardiac graft and to protect it from the impending reperfusion insult that frequently accompanies liver transplantation. The utility of this management course is discussed, along with its actual and potential complications. We also describe the impact of a lung-protective ventilation strategy employed during cardiac transplantation.

Transthyretin-related familial amyloidotic polyneuropathy-Progress in Kumamoto, Japan (1967-2010)-

The authors reviewed contribution of Kumamoto University group to the progress of the studies on transthyretin (TTR)-related familial amyloidotic polyneuropathy (TTR-related FAP) for 42 years (from 1967 to 2009). Andrade (1952) first described a large group of patients with FAP in Portugal and Araki et al. (1967) in second discovered similar FAP patients in Arao, Kumamoto, Japan. Owing to progress in biochemical and molecular genetic analyses, FAP is now believed to occur worldwide. As of today, reports of about 100 different points of single or two mutations, or a deletion in the transthyretin (TTR) gene, have been published. The authors' group has made pioneer works for study of FAP in the world. The focus on therapy in amylodosis will increase sharply as an impetus in near future, and successful treatments are expected.

[Pathogenesis and therapy for transthyretin related amyloidosis]

Transthyretin (TTR) is a beta-sheet rich protein whose plasma half life is 1.9 days. It behaves as a tetramer and binds to retinol binding protein (RBP) and thyroxin in plasma. Since TTR is a tryptophan-rich-protein, the protein is used as a useful marker protein for nutrition supporting team (NST). However, TTR is also an anti-acute phase protein, and its concentration is influenced by various conditions, such as inflammation and infection. Mutated forms of TTR are the precursor protein of familial amyloidotic polyneuropathy (FAP). Since plasma TTR is predominantly synthesized by the liver, liver transplantation has been performed as an effective therapy for FAP. However, the surgery has several problems, so we must develop novel essential therapies for FAP. Single stranded oligonucleotides (SSOs) or short interference RNA (SiRNA) is a promising option for an essential therapy for FAP. In mutated TTR, instability of tetrameric form of TTR occurs, resulting in misfolding of TTR molecule, which lead to amyloid fibril formation. Since mutated TTR exposes criptic epitopes on the surface of TTR molecule, induction of an antibody for the epitopes was thought to be effective. We synthesized ATTR Y78P, a spontaneously misfolded TTR, and injected it to amyloid laden transgenic mice having human ATTR V30M to induce the antibody for amyloid fibrils. As we expected, amyloid deposition was significantly reduced by the injection of ATTR Y78P to the mice. These therapies may become novel strategies for essential FAP therapy instead of liver transplantation.

[The diagnosis and management of familial amyloid polyneuropathy]

INTRODUCTION

Familial amyloid polyneuropathy designates a group of dominantly inherited neuropathies, with extracellular deposition of amyloid substance in various tissues.

BACKGROUND

The 3 main precursor proteins encountered in these disorders are transthyretin, apolipoprotein A1 or gelsolin. Among them, transthyretin neuropathies are by far the most frequent type with a severe sensori-motor and autonomic neuropathy as the hallmark of the disease, most often associated with cardiac manifestations. First described in Portugal, the affection was subsequently reported across the world, although Portugal, Japan and Sweden are the 3 main areas of prevalence. In the past years, an increasing number of mutations have been identified in the TTR gene, along with a larger clinical spectrum than initially thought. Variable age of onset and penetrance are also largely reported with unclear phenotypic-genotypic correlations. Indeed, the contribution of the molecular genetics is important to ensure the diagnosis at an early stage, but also for predictive diagnosis, in the setting of genetic counselling.

PERSPECTIVES

Over the last 15 years, liver transplantation (LT) has enabled improved prognosis of this devastating condition.

FUTURE PROSPECTS

at present, such procedure should be performed in Val30Met patients, as early as possible in the course of the disease. Experience with such procedure in patients with other TTR variants remains scarce. Other therapeutic strategies are awaited.

CONCLUSION

This review summarizes the recent data on the diagnosis and management of patients and families affected with TTR amyloid neuropathy.

[Autonomic dysfunction in FAP: its therapeutic effect by liver transplantation]

FAP is characterized by progressive polyneuropathy and autonomic dysfunction and the latter consists of marked orthostatic hypotension, disturbed bowel movement, impotence and urinary incontinence. All these autonomic symptoms severely affect patient's daily activity. The precursor protein of amyloid fibrils in this disease is a variant form of transthyretin (TTR) in serum. Since TTR is produced mainly in the liver, liver transplantation has been employed for FAP patients as only one curative treatment. During the past 12 years more than 50 FAP patients underwent liver transplantation in Japan and the five-year survival rate of them was 77%. Early intervention (less than 5 years after onset) can provide a better chance of improving patients' condition after transplantation and gastrointestinal autonomic symptoms that include severe episodic nausea, vomiting, and alternating constipation and diarrhea significantly relieve shortly after operation. Preoperative clinical severity and the nutritional status of patients are correlated with their outcome after liver transplantation. Among them the presence of an autonomic failure in FAP patients seems to be contraindication for this challenging operation.

Liver transplantation and new therapeutic approaches for familial amyloidotic polyneuropathy (FAP)

Liver transplantation has been considered as a promising therapy to halt the progression of clinical symptoms in familial amyloidotic polyneuropathy (FAP) because most transthyretin (TTR) is produced by the liver. In addition, domino liver transplantation using an FAP patient's liver has been performed because of a shortage of donor livers. However, because the use of liver transplantation as therapy for FAP has given rise to several problems, an alternative treatment is needed. We have tried several other approaches. Recent studies suggested that certain metal ions affect amyloidogenesis. Among metal ions tested in an in vitro amyloid formation study, Cr3+ increased stability of both normal and mutant TTR tetramers and suppressed TTR amyloidogenesis induced by low pH. Our findings indicate that Cr3+ acts to suppress TTR amyloidogenesis. BSB, a Congo red derivative that binds to amyloid fibrils in FAP as well as to those in senile plaques in Alzheimer's disease, effectively suppressed TTR amyloid formation in vitro. BSB may thus be useful for preventing amyloid formation. Free radical scavenger therapy was also tried in FAP patients but yielded no conclusive results. Immunization for transgenic mice having the ATTR V30M gene using ATTR Y78P resulted in suppression of amyloid deposits. Finally, an RNA/DNA chimera and single-stranded oligonucleotides (SSOs) were tested in vitro and in vivo in an attempt to repair the amyloidogenic TTR gene in the liver and retina. On the basis of results achieved so far, SSO is a promising tool for gene therapy.

Cutaneous manifestations of familial amyloidotic polyneuropathy

Familial amyloidotic polyneuropathy is an autosomal dominant amyloidosis, characterized by the systemic deposition of amyloid with a particular involvement of the peripheral nerves. The disease generally manifests as a severe sensory, motor and autonomic neuropathy. Cardiomyopathy, nephropathy, vitreous opacities and carpal tunnel syndrome may occur in a variable association with the neuropathy. Trophic dermatological lesions are frequent in the more advanced stages of the disease. We examined the skin of 142 patients. The cutaneous manifestations more frequently observed were: xerosis (81.6%), seborrheic dermatitis (21.8%), traumatic and burn lesions (19.7%), acne (18.3%), neurotrophic ulcers (14%) and onychomycosis (10.5%). Among the hepatic transplanted patients (31%), seborrheic dermatitis and acne were the most frequent diagnoses.

Applications of gene therapy for familial amyloidotic polyneuropathy

Familial amyloidotic polyneuropathy (FAP), caused by mutated transthyretin (TTR), is the common form of hereditary generalised amyloidosis. As TTR is predominantly synthesised in the liver, liver transplantation is now considered an effective treatment for FAP to halt the production of variant TTR. However, this invasive therapy has several problems, leading to a requirement for a non-invasive treatment to be developed. At present, gene therapy for FAP has focused on two therapeutic strategies for suppressing variant TTR gene expression. The first is inhibition of variant TTR mRNA expression by antisense or ribozymes, and the other is the repair of mutated TTR gene by chimaeraplasts or single-stranded oligonucleotides. In particular, targeted gene repair is considered to be a promising tool for gene therapy because the effect can last permanently and the method is more suitable for proteins with a short plasma half-life. This article summarises the general concept of gene therapy and reviews the recent data on gene therapy for FAP.

[Gene therapy in familial amyloidotic polyneuropathy by single-stranded oligonucleotides (SSOs)]

Transthyretin (TTR) related familial amyloidotic polyneuropathy (FAP) is the common form of hereditary generalized amyloidosis and is characterized by the accumulation of amyloid deposits in the peripheral nerves and other organs. Liver transplantation has been utilized as therapy for FAP, because the variant TTR is predominantly synthesized by the liver, but this therapy is associated with several problems. Since we need to develop a new treatment, we examined the feasibility of gene therapy in FAP to prevent the production of variant TTR in the liver by using single-stranded oligonucleotides (SSOs). To examine in vitro and in vivo conversion of the TTR gene by SSOs embedded in atelocollagen, we used HepG2 cells and liver from transgenic mice whose intrinsic wild-type TTR gene was replaced by the mouse TTR V30M gene. The level of gene conversion was determined by real-time RCR combined with mutant-allele-specific amplification. The level of gene conversion was approximately 11% and 9% of the total TTR gene in HepG2 cells and liver from transgenic mice, respectively. Therefore, gene therapy via this method may be a promising alternative to liver transplantation for treatment of FAP.

Liver transplantation in transthyretin-related familial amyloid polyneuropathy

PURPOSE OF REVIEW

Familial amyloid polyneuropathy (FAP) associated with mutations in the gene for transthyretin is a rare, progressively disabling and ultimately fatal inherited disease. Transthyretin is produced predominantly in the liver, and orthotopic liver transplantation (OLT) eliminates more than 95% of variant amyloidogenic transthyretin from the circulation. Liver transplantation remains the only potentially curative treatment in this disorder, but many recent studies have suggested that outcome following transplantation may be poorer than previously considered in some groups of FAP patients.

RECENT FINDINGS

We review here the available data on the use and clinical outcome of OLT in patients with FAP, and consider the significance of particular mutations and cardiac amyloid involvement. The practice of combined organ transplants and domino liver transplantation is also reviewed.

SUMMARY

Published data generally support OLT as a treatment for FAP, particularly in younger patients with the most prevalent transthyretin (TTR) Met30 variant, who have mild symptoms. Although excellent outcomes have been reported, including improvement in autonomic and to a lesser extent peripheral nerve function coupled with regression of visceral amyloid deposits, the results of OLT are influenced by many factors that include properties of particular transthyretin variants, nutritional status, age, severity of neuropathy and cardiac amyloid involvement. Paradoxical acceleration of transthyretin amyloid deposition following OLT may occur in the heart and certain other sites in some patients. The combination of kidney or heart transplantation with OLT may occasionally be appropriate. The long-term outcome of patients with FAP who have undergone OLT, and recipients of FAP domino liver transplants, remain to be determined.

Outcome of exercise electrocardiography in familial amyloidotic polyneuropathy patients, Portuguese type, under evaluation for liver transplantation

Familial amyloidotic polyneuropathy (FAP) is a dominantly inherited systemic amyloidosis caused by mutated transthyretin (TTR). Liver transplantation is currently the only available treatment that halts the progress of the disease. Cardiovascular complications are common in FAP, and cardiac arrhythmias are typical complications in FAP Val30Met. For patients with late onset FAP, as the Swedish patients, coronary heart disease has been found in several patients, and a QS complex is not an uncommon finding in FAP-patients ECG raising the suspicion of coronary heart disease. The aim of this study was to evaluate exercise ECG in FAP patients before transplantation with regard to mortality and morbidity. Thirty-eight FAP patients who underwent examination by exercise ECG, as part of the evaluation for liver transplantation were included in the study. Of these, 30 patients were transplanted, and the surviving patients were followed for at least 2 years. Exercise ECG was performed on bicycles with standard 12 leads. Non-parametric statistical analyses were used in all calculations. Six patients died 0-5.5 years after transplantation. They were older than the survivors (p < 0.01), but their duration of disease did not deviate from that of survivors (p = 0.8). They were also less able to increase their heart rates during exercise than the survivors (p < 0.05). For all transplanted patients, a significant relationship was found between patients' increase of heart rate, blood pressure and maximal workload, and the duration of disease and also for the PND-score, signifying that the outcome of exercise ECG predominantly was related to the patients autonomic and motor function, and not to their heart function.

End-stage renal disease and dialysis in hereditary amyloidosis TTR V30M: presentation, survival and prognostic factors

Classical familial amyloid polyneuropathy may have a course with progressive renal impairment. We studied 62 patients (24 males, 38 females) with FAP, transthyretin variant V30M, and end-stage renal disease (ESRD) treated with hemodialysis, all referred to a single center over a period of 11 years. Clinical course, morbidity and survival after dialysis were analyzed. Patient's mean age at first dialysis was 51.5 +/- 10.7 years, and mean duration of neuropathy was 10.2 +/- 3.8 years. The most frequent form of presentation of FAP nephropathy was nephrotic proteinuria with renal dysfunction. In the year prior to dialysis, renal function declined rapidly, and fluid overload was the main indication to initiate treatment. The presence of decubitus ulcers, significant disability, venous catheter for definitive vascular access for long-term treatment, and permanent bladder catheter, were related to death during the first year of dialysis. The mean duration of renal replacement therapy was 21 months, with a 54.5% one year, and 38.4% two year treatment survival. However, when the duration of neurological symptoms at first dialysis exceeded 10 years, survival was significantly lower. Infections, (41% were decubitus ulcers with sepsis) were the cause of early, as well as late mortality. Early creation of vascular access for hemodialysis, surveillance of skin wounds, and intervention on neurogenic bladder are essential to improve the prognosis of ESRD in FAP.

Familial amyloidotic polyneuropathy with severe renal involvement in association with transthyretin Gly47Glu in Dutch, British and American-Finnish families

Familial amyloidotic polyneuropathy (FAP) is an autosomal dominant disorder associated with more than 80 different transthyretin (TTR) mutations. The clinical features of FAP are broad and variable, but knowledge of the pattern and natural history of disease associated with particular mutations nevertheless offers the best guidance for management of individual patients, including the role and timming of treatment by orthotopic liver transplantation. FAP in association with TTR Gly47Glu has been described previously in an Italian kindred, and we report here its phenotype in 7 additional patients from Dutch, British, and American (Finnish) families. Characteristic clinical features included amyloid cardiomyopathy and autonomic failure but, unusually, moderate to severe renal failure was present in more than half of the cases. Only four patients were deemed to be sufficiently fit to undergo orthotopic liver transplantation, and clinical deterioration was generally rapid. These observations support early intervention with orthotopic liver transplantation in patients with FAP associated with TTR Gly47Glu.

Report from the Familial Amyloidotic Polyneuropathy World Transplant Registry (FAPWTR) and the Domino Liver Transplant Registry (DLTR)

Familial amyloidotic polyneuropathy (FAP) is a fatal disease, belonging to a group of systemic disorders caused by an amyloidogenic transthyretin (TTR) variant. Orthotopic liver transplantation (OLT) eliminates the source of the variant TTR molecule, and is presently the only known curative treatment. A fascinating consequence of this treatment is the possibility of retransplanting the removed FAP liver into another non-FAP patient, which created the so-called domino liver transplantation (DLT) procedure. The Familial Amyloidotic Polyneuropathy World Transplant Registry (FAPWTR) was initiated in 1995, and in 1999 a Domino Liver Transplantation Registry (DLTR) was created. Herein data from these Registries are presented. A total number of 56 centers in 16 countries have performed OLT for FAP, and, today, approximately 65-70 OLTs are performed annually worldwide. During the last decade, a total of 623 patients have undergone 660 OLTs. Patient survival is excellent and comparable to the survival with OLT performed for other chronic liver disorders. Twenty-six centers in 12 countries have reported recipients of DLT grafts and presently 30-35 DLTs are performed annually. The FAPWTR and DLTR have become useful tools in evaluating the potential risks and benefits of these relatively new therapeutic options, in addition to encouraging a rewarding collaboration between centers involved in the management of these patients.