Evolving landscape in the management of transthyretin amyloidosis

Cardiac Amyloidosis Mimicking Non-ST-Segment Myocardial Infarction: A Case Report

Cardiac amyloidosis is a rare but increasingly recognized condition characterized by the deposition of amyloid fibrils in cardiac tissue, leading to structural and functional heart impairment. This infiltrative cardiomyopathy often mimics more common cardiac conditions, posing significant diagnostic challenges. Particularly deceptive is its presentation as non-ST-segment elevation myocardial infarction (NSTEMI), where the clinical overlap necessitates considering amyloidosis in differential diagnoses. A 75-year-old male presented with muscle weakness, respiratory infection symptoms, and elevated cardiac enzymes. His history included a recent hospitalization for NSTEMI, with normal coronary angiography. Initial evaluations showed elevated troponin and CRP levels. A comprehensive cardiac assessment revealed a dilated ascending aorta, moderate systolic dysfunction (left ventricular ejection fraction (LV-EF), 47%), and asymmetrical interventricular septal thickening, suggesting hypertrophic cardiomyopathy or amyloidosis. The patient improved and was referred for further specialized care. Cardiac amyloidosis can mimic acute coronary syndrome (ACS), presenting with chest pain and elevated cardiac biomarkers. Differentiation is critical as amyloidosis involves myocardial infiltration by amyloid proteins, leading to restrictive cardiomyopathy. Advanced imaging techniques like cardiac MRI and nuclear scintigraphy are essential for accurate diagnosis and appropriate management, impacting therapeutic strategies and patient outcomes.

Early diagnosis in ATTRv amyloidosis, how early is enough? How early is possible?

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) is a rare, progressive, and debilitating genetic disorder characterized by the deposition of abnormal transthyretin (TTR) protein aggregates in various tissues, leading to organ dysfunction. Early diagnosis of ATTRv amyloidosis is critical for starting timely interventions and improving patient outcomes. This review explores the concepts of "how early is enough" and "how early is possible" in the context of diagnosing ATTRv amyloidosis, highlighting the challenges and opportunities for early recognition.

Impact of Baseline Neuropathy Severity on Vutrisiran Treatment Response in the Phase 3 HELIOS-A Study

INTRODUCTION

Hereditary transthyretin (ATTRv, v for variant) amyloidosis is a rare, progressive, fatal disease with multisystem manifestations, caused by pathogenic variants in the transthyretin (TTR) gene. Vutrisiran, an RNA interference therapeutic that results in rapid TTR knockdown, improved neuropathy and quality of life (QOL) versus external placebo in patients with ATTRv amyloidosis with polyneuropathy in the phase 3 HELIOS-A study (NCT03759379). This post hoc analysis evaluates the impact of baseline neuropathy severity on response to vutrisiran treatment.

METHODS

Patients were randomized (3:1) to vutrisiran (n = 122; 25 mg subcutaneous injection once every 3 months) or patisiran (n = 42; 0.3 mg/kg intravenous infusion once every 3 weeks), which served as a reference group. In this post hoc analysis, patients were grouped into quartiles of increasing baseline Neuropathy Impairment Score (NIS): Quartile (Q)1 ≥ 5.0 to ≤ 20.5; Q2 > 20.5 to ≤ 44.1; Q3 > 44.1 to ≤ 73.1; Q4 > 73.1 to ≤ 127.0. Mean change from baseline to Month 18 was summarized by quartile for a range of efficacy endpoints.

RESULTS

Across all baseline NIS quartiles, vutrisiran demonstrated benefit versus external placebo in measures of neuropathy severity (modified NIS + 7), QOL (Norfolk Quality of Life-Diabetic Neuropathy), disability (Rasch-built Overall Disability Scale), gait speed (10-m walk test), and nutritional status (modified body mass index). Overall, patients in lower versus higher NIS quartiles (less severe neuropathy) at baseline maintained better scores at Month 18. The external placebo group progressively worsened in all measures at Month 18.

CONCLUSIONS

Vutrisiran demonstrated benefit in neurologic function and other key efficacy measures versus external placebo across all four baseline neuropathy severity quartiles. Patients initiating vutrisiran earlier in their disease course retained the highest neurologic function level after 18 months, highlighting the importance of early diagnosis and treatment.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT03759379.

Frameworks for transformational breakthroughs in RNA-based medicines

RNA has sparked a revolution in modern medicine, with the potential to transform the way we treat diseases. Recent regulatory approvals, hundreds of new clinical trials, the emergence of CRISPR gene editing, and the effectiveness of mRNA vaccines in dramatic response to the COVID-19 pandemic have converged to create tremendous momentum and expectation. However, challenges with this relatively new class of drugs persist and require specialized knowledge and expertise to overcome. This Review explores shared strategies for developing RNA drug platforms, including layering technologies, addressing common biases and identifying gaps in understanding. It discusses the potential of RNA-based therapeutics to transform medicine, as well as the challenges associated with improving applicability, efficacy and safety profiles. Insights gained from RNA modalities such as antisense oligonucleotides (ASOs) and small interfering RNAs are used to identify important next steps for mRNA and gene editing technologies.

ATTRv-V30M Type A amyloid fibrils from heart and nerves exhibit structural homogeneity

ATTR amyloidosis is a systemic disease characterized by the deposition of amyloid fibrils made of transthyretin, a protein integral to transporting retinol and thyroid hormones. Transthyretin is primarily produced by the liver and circulates in blood as a tetramer. The retinal epithelium also secretes transthyretin, which is secreted to the vitreous humor of the eye. Because of mutations or aging, transthyretin can dissociate into amyloidogenic monomers triggering amyloid fibril formation. The deposition of transthyretin amyloid fibrils in the myocardium and peripheral nerves causes cardiomyopathies and neuropathies, respectively. Using cryo-electron microscopy, here we determined the structures of amyloid fibrils extracted from cardiac and nerve tissues of an ATTRv-V30M patient. We found that fibrils from both tissues share a consistent structural conformation, similar to the previously described structure of cardiac fibrils from an individual with the same genotype, but different from the fibril structure obtained from the vitreous humor. Our study hints to a uniform fibrillar architecture across different tissues within the same individual, only when the source of transthyretin is the liver. Moreover, this study provides the first description of ATTR fibrils from the nerves of a patient and enhances our understanding of the role of deposition site and protein production site in shaping the fibril structure in ATTRv-V30M amyloidosis.

Treatment characteristics of patients with hereditary transthyretin amyloidosis: a cohort study

BACKGROUND

There are novel medications approved for the treatment of hereditary transthyretin amyloidosis (ATTRv), classified as transthyretin (TTR) stabilizers or gene silencers. While many patients may be on both classes of medications, there is no data available on the safety and efficacy of combination therapy.

OBJECTIVES

To describe ATTRv patient and TTR-targeted therapy characteristics in a US cohort, and compare outcomes with combination therapy versus monotherapy.

METHODS

We performed a retrospective cohort study with electronic health record data of patients with ATTRv seen at a single institution between January 2018 and December 2022. We collected data on symptomatology, gene mutation, disease severity, ATTRv treatment, hospitalizations, and mortality.

RESULTS

One hundred sixty-two patients with ATTRv were identified. The average age at diagnosis was 65 years. 86 patients (53%) had the V122I variant. 119 patients were symptomatic, of whom 103 were started on ATTRv-specific treatment. 41 patients (40%) had cardiomyopathy only, and 53 (51%) had a mixed phenotype of cardiomyopathy and neuropathy. 38 patients (37%) received therapy with both a gene silencer and protein stabilizer. 9 patients (15%) in the monotherapy group had two or more cardiac hospitalizations after starting treatment, compared to 3 patients (9%) on combination therapy (p=0.26). The adjusted hazard ratio of all-cause mortality for the patients on combination therapy compared to monotherapy was 0.37 (0.08-1.8, p=0.21).

CONCLUSIONS

While the efficacy is unproven, over one-third of patients with ATTRv are on both a stabilizer and a silencer. There were no safety issues for combination therapy. There was a trend towards improved hospitalizations and survival in patients in the combination group but this was not statistically significant. Larger studies with longer follow-up are necessary to determine benefit of combination therapy.

Late-onset familial amyloidosis polyneuropathy associated with c.186G>C in transthyretin

INTRODUCTION

The most common form of hereditary amyloidosis is associated with variants of transthyretin (TTR). Familial amyloidosis polyneuropathy associated with variants of TTR (FAP-TTR) is an infrequent, multisystemic disease, with predominant involvement of the peripheral nervous system. More than 130 pathogenic variants have been identified so far and most of them are amyloidogenic, being Val30Met the most frequently described.

CASE REPORT

A 74 year-old male was evaluated for progressive decreased sensitivity and associated loss of strength in four limbs in the previous two years, needing assistance for walking. Areflexia, bilateral tibialis anterior and gastrocnemius atrophy, bilateral anesthesia and apalesthesia were found in lower limbs. Bilateral hypoesthesia was reported in upper limbs. No painful dysesthesia, hyperalgesia or allodynia were found. DNA sequencing of the TTR gene led to the detection of the variant c.186G>C in heterozygous state. The resulting variant (Glu62Asp), located in the critical functional domain, has not been published before.

CONCLUSION

The importance of considering late onset, sporadic FAP-TTR as a differential diagnosis of cryptogenic polyneuropathy is highlighted.

Characterization of Transthyretin Mutation G47V Associated with Hereditary Cardiac Amyloidosis

INTRODUCTION

Amyloidosis caused by TTR mutations (ATTRv) is a rare inherited and autosomal dominant disease. More than 150 mutants of TTR have been reported, whereas some of them remain to be investigated.

METHODS

A 52-year-old male presented with heart failure and clinically diagnosed ATTR cardiac amyloidosis (ATTR-CA) was recruited. Whole-exome sequencing (WES) was performed. Biochemical and biophysical experiments characterized protein stability using urea-mediated tryptophan fluorescence. Drug response was analyzed by fibril formation assay. Finally, tetramer TTR concentration in patient's serum sample was measured by ultra-performance liquid chromatography (UPLC).

RESULTS

For the proband, WES revealed a mutation (c.200G>T; p.Gly67Val and referred to as G47V) in TTR gene. Biochemical and biophysical kinetics study showed that the thermodynamic stability of G47V-TTR (Cm = 2.4 m) was significantly lower than that of WT-TTR (Cm = 3.4 m) and comparable to that of L55P-TTR (Cm = 2.3 m), an early age-of-onset mutation. G47V:WT-TTR heterozygous tetramer kinetic stability (t1/2 = 1.4 h) was further compromised compared to that of the homozygous G47V-TTR (t1/2 = 3.1 h). Among three small molecule stabilizers, AG10 exhibited the best inhibition of the fibrillation of G47V-TTR homozygous protein. Using a UPLC assay, nearly 40% of TTR in this patient was calculated to be non-tetrameric.

CONCLUSION

In this work, we reported a patient presented early onset of clinically typical ATTR-CA due to G47V-TTR mutation. Our work for the first time not only characterized the biochemical properties of G47V-TTR mutation, but also provided hints for the pathogenicity of this mutation.

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.

Targeting the Liver with Nucleic Acid Therapeutics for the Treatment of Systemic Diseases of Liver Origin

Systemic diseases of liver origin (SDLO) are complex diseases in multiple organ systems, such as cardiovascular, musculoskeletal, endocrine, renal, respiratory, and sensory organ systems, caused by irregular liver metabolism and production of functional factors. Examples of such diseases discussed in this article include primary hyperoxaluria, familial hypercholesterolemia, acute hepatic porphyria, hereditary transthyretin amyloidosis, hemophilia, atherosclerotic cardiovascular diseases, α-1 antitrypsin deficiency-associated liver disease, and complement-mediated diseases. Nucleic acid therapeutics use nucleic acids and related compounds as therapeutic agents to alter gene expression for therapeutic purposes. The two most promising, fastest-growing classes of nucleic acid therapeutics are antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs). For each listed SDLO disease, this article discusses epidemiology, symptoms, genetic causes, current treatment options, and advantages and disadvantages of nucleic acid therapeutics by either ASO or siRNA drugs approved or under development. Furthermore, challenges and future perspectives on adverse drug reactions and toxicity of ASO and siRNA drugs for the treatment of SDLO diseases are also discussed. In summary, this review article will highlight the clinical advantages of nucleic acid therapeutics in targeting the liver for the treatment of SDLO diseases. SIGNIFICANCE STATEMENT: Systemic diseases of liver origin (SDLO) contain rare and common complex diseases caused by irregular functions of the liver. Nucleic acid therapeutics have shown promising clinical advantages to treat SDLO. This article aims to provide the most updated information on targeting the liver with antisense oligonucleotides and small interfering RNA drugs. The generated knowledge may stimulate further investigations in this growing field of new therapeutic entities for the treatment of SDLO, which currently have no or limited options for treatment.

Recent Progress in the Development and Clinical Application of New Drugs for Transthyretin Cardiac Amyloidosis

ABSTRACT

Transthyretincardiac amyloidosis is a rare disease that has gained significant attention in recent years because of misfolding of transthyretin fibrils produced by the liver, leading to their deposition in the myocardium. The disease has an insidious onset, nonspecific clinical manifestations, and historically lacked effective drugs, making early diagnosis and treatment challenging. The survival time of patients largely depends on the extent of heart involvement at the time of diagnosis, and conventional treatments for cardiovascular disease do not provide significant benefits. Effective management of the disease requires treatment of its underlying cause. Orthotopic liver transplantation and combined hepato-heart transplantation have been clinically effective means of treating transthyretin cardiac amyloidosis mutants for many years. However, transplantation has many limitations in clinical practice. In recent years, the development of new drugs has brought new hope to patients. This review presents the latest advances in drug development and clinical application to provide a reference for clinicians managing transthyretin cardiac amyloidosis.

Detecting transthyretin amyloid cardiomyopathy (ATTR-CM) using machine learning: an evaluation of the performance of an algorithm in a UK setting

OBJECTIVE

The aim of this study was to evaluate the potential real-world application of a machine learning (ML) algorithm, developed and trained on heart failure (HF) cohorts in the USA, to detect patients with undiagnosed wild type cardiac amyloidosis (ATTRwt) in the UK.

DESIGN

In this retrospective observational study, anonymised, linked primary and secondary care data (Clinical Practice Research Datalink GOLD and Hospital Episode Statistics, respectively, were used to identify patients diagnosed with HF between 2009 and 2018 in the UK. International Classification of Diseases (ICD)-10 clinical modification codes were matched to equivalent Read (primary care) and ICD-10 WHO (secondary care) diagnosis codes used in the UK. In the absence of specific Read or ICD-10 WHO codes for ATTRwt, two proxy case definitions (definitive and possible cases) based on the degree of confidence that the contributing codes defined true ATTRwt cases were created using ML.

PRIMARY OUTCOME MEASURE

Algorithm performance was evaluated primarily using the area under the receiver operating curve (AUROC) by comparing the actual versus algorithm predicted case definitions at varying sensitivities and specificities.

RESULTS

The algorithm demonstrated strongest predictive ability when a combination of primary care and secondary care data were used (AUROC: 0.84 in definitive cohort and 0.86 in possible cohort). For primary care or secondary care data alone, performance ranged from 0.68 to 0.78.

CONCLUSION

The ML algorithm, despite being developed in a US population, was effective at identifying patients that may have ATTRwt in a UK setting. Its potential use in research and clinical care to aid identification of patients with undiagnosed ATTRwt, possibly enabling earlier diagnosis in the disease pathway, should be investigated.

Impact of Vutrisiran on Quality of Life and Physical Function in Patients with Hereditary Transthyretin-Mediated Amyloidosis with Polyneuropathy

INTRODUCTION

Hereditary transthyretin (ATTRv; v for variant) amyloidosis, also known as hATTR amyloidosis, is a progressive and fatal disease associated with rapid deterioration of physical function and patients' quality of life (QOL). Vutrisiran, a subcutaneously administered RNA interference (RNAi) therapeutic that reduces hepatic production of transthyretin, was assessed in patients with ATTRv amyloidosis with polyneuropathy in the pivotal HELIOS-A study.

METHODS

The phase 3 open-label HELIOS-A study investigated the efficacy and safety of vutrisiran in patients with ATTRv amyloidosis with polyneuropathy, compared with an external placebo group from the APOLLO study of the RNAi therapeutic patisiran. Measures of QOL and physical function were assessed.

RESULTS

At month 18, vutrisiran improved Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) total score (least squares mean difference [LSMD] in change from baseline [CFB]: -21.0; p = 1.84 × 10-10) and Norfolk QOL-DN domain scores, compared with external placebo. This benefit relative to external placebo was evident across all baseline polyneuropathy disability (PND) scores and most pronounced in patients with baseline PND scores I-II. Compared with external placebo, vutrisiran also demonstrated benefit in EuroQoL-Visual Analog Scale (EQ-VAS) score (LSMD in CFB: 13.7; nominal p = 2.21 × 10-7), 10-m walk test (LSMD in CFB: 0.239 m/s; p = 1.21 × 10-7), Rasch-built Overall Disability Score (LSMD in CFB: 8.4; p = 3.54 × 10-15), and modified body mass index (mBMI) (LSMD in CFB: 140.7; p = 4.16 × 10-15) at month 18. Overall, Norfolk QOL-DN, EQ-VAS, and mBMI improved from pretreatment baseline with vutrisiran, whereas all measures worsened from baseline in the external placebo group. At month 18, Karnofsky Performance Status was stable/improved from baseline in 58.2/13.1% with vutrisiran versus 34.7/8.1% with external placebo.

CONCLUSION

Vutrisiran treatment provided significant clinical benefits in multiple measures of QOL and physical function in patients with ATTRv amyloidosis with polyneuropathy. Benefits were most pronounced in patients with earlier-stage disease, highlighting the importance of early diagnosis and treatment.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT03759379.

The genetic and clinical spectrum in a cohort of 39 families with complex inherited peripheral neuropathies

With complicated conditions and a large number of potentially causative genes, the diagnosis of a patient with complex inherited peripheral neuropathies (IPNs) is challenging. To provide an overview of the genetic and clinical features of 39 families with complex IPNs from central south China and to optimize the molecular diagnosis approach to this group of heterogeneous diseases, a total of 39 index patients from unrelated families were enrolled, and detailed clinical data were collected. TTR Sanger sequencing, hereditary spastic paraplegia (HSP) gene panel, and dynamic mutation detection in spinocerebellar ataxia (SCAs) were performed according to the respective additional clinical features. Whole-exome sequencing (WES) was used in patients with negative or unclear results. Dynamic mutation detection in NOTCH2NLC and RCF1 was applied as a supplement to WES. As a result, an overall molecular diagnosis rate of 89.7% was achieved. All 21 patients with predominant autonomic dysfunction and multiple organ system involvement carried pathogenic variants in TTR, among which nine had c.349G > T (p.A97S) hotspot variants. Five out of 7 patients (71.4%) with muscle involvement harbored biallelic pathogenic variants in GNE. Five out of 6 patients (83.3%) with spasticity reached definite genetic causes in SACS, KIF5A, BSCL2, and KIAA0196, respectively. NOTCH2NLC GGC repeat expansions were identified in all three cases accompanied by chronic coughing and in one patient accompanied by cognitive impairment. The pathogenic variants, p.F284S and p.G111R in GNE, and p.K4326E in SACS, were first reported. In conclusion, transthyretin amyloidosis with polyneuropathy (ATTR-PN), GNE myopathy, and neuronal intranuclear inclusion disease (NIID) were the most common genotypes in this cohort of complex IPNs. NOTCH2NLC dynamic mutation testing should be added to the molecular diagnostic workflow. We expanded the genetic and related clinical spectrum of GNE myopathy and ARSACS by reporting novel variants.

Synthesis and clinical application of new drugs approved by FDA in 2022

The pharmaceutical industry had a glorious year in 2022, with a total of 37 new drugs including 20 new chemical entities (NCEs) and 17 new biological entities (NBEs) approved by the Food and Drug Administration (FDA). These drugs are mainly concentrated in oncology, central nervous system, antiinfection, hematology, cardiomyopathy, dermatology, digestive system, ophthalmology, MRI enhancer and other therapeutic fields. Of the 37 drugs, 25 (68%) were approved through an expedited review pathway, and 19 (51%) were approved to treat rare diseases. These newly listed drugs have unique structures and new mechanisms of action, which can serve as lead compounds for designing new drugs with similar biological targets and enhancing therapeutic efficacy. This review aims to outline the clinical applications and synthetic methods of 19 NCEs newly approved by the FDA in 2022, but excludes contrast agent (Xenon Xe-129). We believe that an in-depth understanding of the synthetic methods of drug molecules will provide innovative and practical inspiration for the development of new, more effective, and practical synthetic techniques. According to the therapeutic areas of these 2022 FDA-approved drugs, we have classified these 19 NCEs into seven categories and will introduce them in the order of their approval for marketing.

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

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

Structure restoration and aggregate inhibition of V30M mutant transthyretin protein by potential quinoline molecules

Transthyretin (TTR) is a tetrameric protein found in human plasma and cerebrospinal fluid that functions as a transporter of thyroxine (T4) and retinol. A mutation resulting in the substitution of valine to methionine at position 30 (V30M) is the most common mutation that destabilizes the tetramer structure of TTR protein resulting in a fatal neuropathy known as TTR amyloidosis. The V30M TTR-induced neuropathy can be inhibited through stabilization of the TTR tetramer by the binding of small molecules. We accessed the potential of in-house synthesized quinoline molecules to stabilize the V30M TTR structure and analyzed the impact of protein-ligand interactions through molecular docking, molecular dynamics (MD) simulations, steered MD, and umbrella sampling simulations. This study revealed that the binding of quinoline molecules reverted back the structural changes including the residual flexibility, changes in secondary structural elements, and also restored the alterations in the electrostatic surface potential induced by the V30M mutation. Further, the top-most 4G and 4R molecules were compared with an FDA-approved drug (Tafamidis) and a reference quinoline molecule 14C. Here, we intend to suggest that the quinoline molecules could revert the structural changes, cease tetramer dissociation, prevent abnormal oligomerization and therefore could be developed as an effective therapeutics against TTR amyloidosis.

Impact of baseline polyneuropathy severity on patisiran treatment outcomes in the APOLLO trial

OBJECTIVE

Assess how baseline polyneuropathy severity impacts response to patisiran regarding neurologic impairment and quality of life (QOL) in patients with hereditary transthyretin-mediated amyloidosis (ATTRv amyloidosis).

METHODS

This post hoc analysis grouped patients from the Phase 3 APOLLO study (n = 225) by baseline Neuropathy Impairment Score (NIS) into quartiles: 6-<31; 31-<57; 57-<85.5; 85.5-141.6. Neurologic impairment (modified NIS+7 [mNIS+7], NIS total score), disability (Rasch-built Overall Disability Scale [R-ODS]), gait speed (10-meter walk test [10-MWT]), grip strength, and QOL (Norfolk Quality of Life-Diabetic Neuropathy [Norfolk QOL-DN] questionnaire) were assessed.

RESULTS

Across all baseline NIS quartiles, patisiran improved several clinical markers of disease compared with placebo at 18 months. Patients in lower NIS quartiles, treated with patisiran earlier in the disease course, maintained better scores in mNIS+7, NIS total score, R-ODS, 10-MWT, grip strength, and Norfolk QOL-DN versus those in higher NIS quartiles, while placebo-treated patients experienced worsening of all functional measures after 18 months across all quartiles.

CONCLUSIONS

Patisiran treatment improved neurologic function and QOL across a wide range of baseline polyneuropathy severities versus placebo. Timing of treatment initiation in patients with ATTRv amyloidosis remains critical for the preservation of function.(ClinicalTrials.gov number, NCT01960348).

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.

A retrospective survey of patients with hereditary transthyretin-mediated (hATTR) amyloidosis treated with patisiran in real-world clinical practice in Belgium

INTRODUCTION

Hereditary transthyretin-mediated (hATTR) amyloidosis, a genetic disease caused by mutations in the transthyretin gene, leads to progressive sensory and autonomic neuropathy and/or cardiomyopathy and is associated with renal and ophthalmologic manifestations and a poor prognosis.

METHODS

This is a retrospective study based on data collected from the medical records of patients with hATTR amyloidosis treated with patisiran between 01 July 2018 and 01 February 2021. Six Belgian neuromuscular reference centers participated, covering all patisiran-treated hATTR amyloidosis patients at the study time. This study was conducted to collect data requested in the context of the reimbursement of patisiran in Belgium.

RESULTS

Thirty-one patients were diagnosed with hATTR amyloidosis with polyneuropathy, Coutinho stage 1 or 2, and eligible for active treatment during the data collection period. Of the hATTR amyloidosis patients treated with patisiran (n = 12), seven and five had polyneuropathy stages 1 and 2, respectively. Six patients had cardiac symptoms (New York Heart Association class 2 or above). Follow-up information was available for nine patients. Following patisiran treatment, eight patients showed stable or improved assessments for most neurological or cardiological parameters. Only one patient presented with worsening statuses at the end of the data collection period.

CONCLUSIONS

The patients with hATTR amyloidosis in Belgium have similar baseline demographics and disease characteristics to those studied in the patisiran APOLLO study and show a similar therapeutic response in the real-world, altering the expected disease progression in most patients.

Research trends and hotspots evolution of cardiac amyloidosis: a bibliometric analysis from 2000 to 2022

In the new century, cardiac amyloidosis has received more attention from many countries and institutions, leading to innovations in the essence of the pathology, biological markers, noninvasive tests, and staging diagnoses and treatments for this disease. However, few reviews have summarized the research trends and hotspots in cardiac amyloidosis. Bibliometrics analysis is a statistically based approach to research that visualizes the contributions of academic institutions and changes in research hotspots. Therefore, in this paper, we used Citespace and VOSviewer software to conduct co-occurrence analysis and collaborative network analysis on the countries, institutions, and authors in the articles related to cardiac amyloidosis since the new century. And further find out burst keywords and references to obtain the research history, disciplinary development, and new hotspots and topics.

Inotersen to Treat Polyneuropathy Associated with Hereditary Transthyretin (hATTR) Amyloidosis

Background

Amyloidosis is a group of diseases with the common pathophysiology of protein misfolding and aberrant deposition in tissue. There are both acquired and hereditary forms of this disease, and this review focuses on the latter hereditary transthyretin-mediated (hATTR). hATTR affects about 50,000 individuals globally and mostly appears as one of three syndromes - cardiac, polyneuropathy, and oculoleptomeningeal. Polyneuropathy is the most common form, and there is usually some overlap in individual patients.

Results

Recently, novel therapeutic options emerged in the form of groundbreaking drugs, Patisiran and Inotersen, small interfering RNA molecules that target TTR and reduce the production of this protein. By targeting TTR mRNA transcripts, Inotersen decreases protein translation and production, reducing the deposition of misfolded proteins. It was shown to be both effective and safe for use and specifically formulated to concentrate in the liver - where protein production takes place.

Conclusion

hATTR is a rare, progressive, and debilitating disease. Its most common presentation is that of polyneuropathy, and it carries a very poor prognosis and a natural history conveying a median survival of < 12 years. Novel therapeutic options are groundbreaking by providing disease-modifying specific, targeted therapies against TTR production and deposition. The use of RNA interference (RNAi) opens the door to the treatment of hereditary diseases by targeting them at the genetic level.

Lessons from the first-in-human in vivo CRISPR/Cas9 editing of the TTR gene by NTLA-2001 trial in patients with transthyretin amyloidosis with cardiomyopathy

Introduction: Transthyretin amyloidosis (ATTR amyloidosis) is a progressive fatal disease characterized by accumulation of amyloid fibrils composed of misfolded transthyretin (TTR) protein in tissues, resulting in cardiomyopathy and heart failure. Approximately 50,000 people have hereditary ATTR amyloidosis, and up to 500,000 have wild-type ATTR amyloidosis globally, leading to poor quality of life and high morbidity, resulting in death within a median of 2 to 6 years after diagnosis. However, data on the prevalence of ATTR-CM is limited and poorly characterized. NTLA-2001, an in vivo gene-editing therapeutic agent designed to treat ATTR amyloidosis by reducing the concentration of TTR in serum by knocking out the TTR gene, has been shown to be effective, presenting a new therapeutic strategy. However, the safety, tolerability, and pharmacodynamic response to IV NTLA-2001 administration has not been yet demonstrated. Study and results: The first-in-human in vivo CRISPR/Cas9 trial of TTR Gene editing by NTLA-2001 in patients with Transthyretin Amyloidosis and cardiomyopathy was designed to evaluate the safety, tolerability, efficacy, and pharmacokinetic and pharmacodynamic responses to IV NTLA-2001 administration and its effect on serum transthyretin (TTR) levels in patients with ATTR amyloidosis and cardiomyopathy. Twelve subjects received NTLA-2001 (three NYHA I/II subjects at 0.7 mg/kg, three subjects at 1.0 mg/kg, and six NYHA III subjects at 0.7 mg/kg). Serum TTR levels were reduced from the baseline in all subjects (mean>90% after 28 days). Mean % reductions (+/-SEM) from baseline to day 28 were: NYHA I/II at 0.7 mg/kg = 92% (1%), at 1.0 mg/kg = 92% (2%), and for NYHA III at 0.7 mg/kg = 94% (1%) maintained through 4-6 months. Two of the 12 patients (16.7%) reported a transient infusion reaction. One patient experienced a grade 3 infusion-related reaction that resolved without any clinical sequelae. Lessons learned: This study showed a significant and consistent reduction in serum TTR protein levels after a single admission, while being generally well tolerated, representing a potential new option for the treatment and improvement of the prognosis of cardiac ATTR amyloidosis. Further research into the long-term safety and efficacy of NTLA-2001, particularly in higher-risk patients, including continued monitoring of whether knockout of the TTR gene results in sustained TTR reduction over the long term, is essential. Evaluation of the potential effects of markedly reduced TTR levels on patients' clinical outcomes, with a focus on functional capacity, quality of life, and mortality benefits are essential. The analysis of the use of this technology for an array of other diseases is vital.

Current Understanding of Systemic Amyloidosis and Underlying Disease Mechanisms

Amyloidosis is a group of diverse disorders caused by misfolded proteins that aggregate into insoluble fibrils and ultimately cause organ damage. In medical practice, amyloidosis classification is based on the amyloid precursor protein type, of which amyloid immunoglobulin light chain, amyloid transthyretin, amyloid leukocyte chemotactic factor 2, and amyloid derived from serum amyloid A protein are the most common. Distinct mechanisms appear to be predominantly operational in the pathogenesis of particular types of amyloidosis, including increased protein precursor synthesis, somatic or germ line mutations, and inherent instability in the precursor protein in its wild form. An increased supply of misfolded proteins and/or a decreased capacity of the protein quality control systems can result in an imbalance that leads to increased circulation of misfolded proteins. Although the detection of mature fibrils is the basis for diagnosis of amyloidosis, a growing body of evidence has implicated the prefibrillar species as proteotoxic and key contributors to the development of the disease.

A natural history analysis of asymptomatic TTR gene carriers as they develop symptomatic transthyretin amyloidosis in the Transthyretin Amyloidosis Outcomes Survey (THAOS)

BACKGROUND

Hereditary transthyretin amyloidosis (ATTRv amyloidosis) results from pathogenic mutations in the transthyretin (TTR) gene. This analysis aimed to better understand ATTRv amyloidosis development in asymptomatic TTR gene carriers.

METHODS

The Transthyretin Amyloidosis Outcomes Survey (THAOS) is an ongoing, global, longitudinal, observational survey of patients with transthyretin amyloidosis, including both inherited and wild-type disease, and asymptomatic TTR gene carriers. Asymptomatic TTR gene carriers were assessed longitudinally to identify those who developed ATTRv amyloidosis after enrolment in THAOS (data cut-off: 1 August 2021).

RESULTS

Of 740 asymptomatic TTR gene carriers, 268 (36.2%) (Val30Met, 212/613 [34.6%]; non-Val30Met, 48/111 [43.2%]) developed ATTRv amyloidosis within a median 2.2 years after enrolment. The most common first symptoms were sensory (49.5%) and autonomic (37.3%) neuropathy in Val30Met patients, and sensory neuropathy (45.8%) and cardiac disorder (22.9%) in non-Val30Met patients. Most patients first presented with a predominantly neurologic phenotype (Val30Met, 77.8%; non-Val30Met, 70.8%).

CONCLUSIONS

More than one-third of asymptomatic TTR gene carriers in THAOS developed ATTRv amyloidosis within a median 2 years of enrolment. Val30Met versus non-Val30Met patients had a lower transition rate. Given the importance of early treatment, these findings underscore the need for identification and careful monitoring of at-risk TTR gene carriers to enable prompt treatment.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00628745.

Petits ARN interférents : applications potentielles pour les néphrologues Small interfering RNA: potential applications for nephrologists

Small interfering RNA (siRNAs) are double-stranded RNAs of around 20 base pairs in length that trigger RNAi machinery, which promotes degradation of a target mRNA avoiding protein translation. SiRNAs are liver-targeted, using tris N-acetylgalactosamine (GalNAc) as the targeting ligand. This discovery received the Nobel Prize for medicine and physiology in 2006 and lead to substantial therapeutic advances. Application field and development of these siRNA has been very fast. Indeed, patisiran has been released in 2018 for hereditary transthyretin amyloidosis. This first treatment showed the security and efficacy of such a product. Since, treatments have been developed for acute hepatic porphyria and primary hyperoxaluria. The current pipeline for new siRNA development is ambitious; clinical trial are ongoing in nephrology, as in the IgA nephropathy. Frequent diseases are also targeted such as hypertension or hypercholesterolemia. © 2022 Published by Elsevier Masson SAS on behalf of Société francophone de néphrologie, dialyse et transplantation.

Biochemical and biophysical properties of an unreported T96R mutation causing transthyretin cardiac amyloidosis

OBJECTIVES

We presented an unreported T96R mutation induced transthyretin cardiac amyloidosis (ATTR). The biochemical and biophysical properties were explored to support its pathogenicity.

BACKGROUND

Understanding the biochemical and biophysical nature of genetically mutated transthyretin (TTR) proteins is key to provide precise medical cares for ATTR patients.

RESULTS

Genetic testing showed heterozygosity for the T96R pathogenic variant c.347C > G (ATTR p.T116R) after myocardial biopsy confirmed amyloid deposition. Biochemical characterizations revealed slight perturbation of its thermodynamic stability (C_m=3.7 M for T96R, 3.4 M for WT and 2.3 M for L55P (commonly studied TTR mutant)) and kinetic stability (t_1/2=39.8 h for T96R, 42 h for WT and 4.4 h in L55P). Crosslinking experiment demonstrated heterozygous subunit exchange between wild-type and TTR T96R protein destabilized the tetramer. Inhibitory effect of tafamidis and diflunisal on TTR T96R fibril formation was slightly less effective compared to WT and L55P.

CONCLUSIONS

A novel T96R mutation was identified for TTR protein. Biochemical and biophysical analyses revealed slightly destabilized kinetic stability. T96R mutation destabilized heterozygous protein but not proteolytic degradation, explaining its pathogenicity. Inhibitory effect of small molecule drugs on T96R mutation was different, suggesting personalized treatment may be required.

Liposomes and liposome-like nanoparticles: From anti-fungal infection to the COVID-19 pandemic treatment

The liposome is the first nanomedicine transformed into the market and applied to human patients. Since then, such phospholipid bilayer vesicles have undergone technological advancements in delivering small molecular-weight compounds and biological drugs. Numerous investigations about liposome uses were conducted in different treatment fields, including anti-tumor, anti-fungal, anti-bacterial, and clinical analgesia, owing to liposome's ability to reduce drug cytotoxicity and improve the therapeutic efficacy and combinatorial delivery. In particular, two liposomal vaccines were approved in 2021 to combat COVID-19. Herein, the clinically used liposomes are reviewed by introducing various liposomal preparations in detail that are currently proceeding in the clinic or on the market. Finally, we discuss the challenges of developing liposomes and cutting-edge liposomal delivery for biological drugs and combination therapy.

Treating Transthyretin Amyloidosis via Adeno-Associated Virus Vector Delivery of Meganucleases

Transthyretin amyloidosis (ATTR) is a progressive and fatal disease caused by transthyretin (TTR) amyloid fibril accumulation in tissues, which disrupts organ function. As the TTR protein is primarily synthesized by the liver, liver transplantation can cure familial ATTR but is not an option for the predominant age-related wild-type ATTR. Approved treatment approaches include TTR stabilizers and an RNA-interference therapeutic, but these require regular re-administration. Gene editing could represent an effective one-time treatment. We evaluated adeno-associated virus (AAV) vector-delivered, gene-editing meganucleases to reduce TTR levels. We used engineered meganucleases targeting two different sites within the TTR gene. AAV vectors expressing TTR meganuclease transgenes were first tested in immunodeficient mice expressing the human TTR sequence delivered using an AAV vector and then against the endogenous TTR gene in rhesus macaques. Following a dose of 3 × 10¹³ genome copies per kilogram, we detected on-target editing efficiency of up to 45% insertions and deletions (indels) in the TTR genomic DNA locus and >80% indels in TTR RNA, with a concomitant decrease in serum TTR levels of >95% in macaques. The significant reduction in serum TTR levels following TTR gene editing indicates that this approach could be an effective treatment for ATTR.

Guidelines and new directions in the therapy and monitoring of ATTRv amyloidosis

The recent approval of three drugs for the treatment of amyloid transthyretin (ATTR) amyloidosis, both hereditary and wild-type, has opened a new era in the care of these diseases. ATTR amyloidosis is embedded in its pathophysiology, and the drugs target critical steps of the amyloid cascade. In addition to liver transplant, which removes the pathogenic variants, the introduction of gene silencers has allowed the suppression of both wild type and mutant transthyretin (TTR), thus extending the potential therapeutic range to wild-type cardiac amyloidosis. The kinetic stabilisation of TTR using small molecules has proved to be clinically effective both for amyloid neuropathy and cardiomyopathy. Gene silencers and kinetic stabilizers were recently approved on the basis of the outcome of phase III trials; however, comparative trials have not been performed, making it difficult to draw recommendations. Indications for liver transplantation have narrowed considerably. Here, guidelines for therapy are proposed based on expert consensus, acknowledging that the several drugs currently undergoing clinical trials will probably change in the near future the therapeutic armamentarium and, consequently, the therapeutic strategy. Indications for monitoring disease progression and drug efficacy are also provided for the management of these complexes, but now very treatable, diseases.

Urinary Transthyretin as a Biomarker in ATTRv Val50Met Amyloidosis

Transthyretin (TTR), the precursor protein for amyloidogenic TTR (ATTR) amyloidosis, forms tetramers and escapes glomerular filtration by binding with thyroxine and retinol-binding protein. However, variant TTRs are unstable as tetramers, so monomeric TTR has become the precursor protein of amyloid deposits, via protein misfolding. The aim of the study was to evaluate the utility of urinary TTR in the diagnosis of ATTRv amyloidosis. Urinary samples from healthy volunteers, ATTRv V50M amyloidosis patients, and asymptomatic carriers of the ATTRv V50M gene were analysed using ELISA. To analyse the different forms of TTR secreted to the urine, we performed Western blotting and mass spectrometry. Urinary TTR concentrations were significantly higher in the ATTRv V50M amyloidosis patients than they were in the healthy volunteers and asymptomatic carriers of the gene. Although the TTR concentrations were negligible in the healthy volunteers, they were correlated with disease progression and urinary albumin concentrations in the ATTRv V50M amyloidosis patients. The Western blotting and mass spectrometry revealed the presence of monomeric wild-type and variant TTRs in the urine. Urinary TTR concentrations may become a more sensitive biomarker of ATTRv progression than albumin.

Cardiac amyloidosis-interdisciplinary approach to diagnosis and therapy

The vast majority of cardiac amyloidosis (CA) cases are caused by light chain (AL) or transthyretin (ATTR) amyloidosis. The latter is divided into hereditary (ATTRv) and wild-type forms (ATTRwt). The incidence of ATTRwt amyloidosis has significantly increased, particularly due to the improved diagnosis of cardiac manifestations, with relevant proportions in patient populations with heart failure (HF) and preserved ejection fraction (HFpEF). Cardiac amyloidosis should be suspected in HF with indicative clinical scenarios/"red flags" with typical signs of CA in echocardiography. Further noninvasive imaging (cardiovascular magnetic resonance imaging, scintigraphy) and specific laboratory diagnostics are important for the diagnosis and typing of CA into the underlying main forms of ATTR and AL amyloidosis. The histopathologic analysis of an endomyocardial biopsy is necessary if noninvasive diagnostic methods do not enable reliable typing of CA. This is crucial for initiating specific therapy. Therapy of HF in CA is largely limited to the use of diuretics in the absence of evidence on the benefit of classic HF therapy with neurohormonal modulators. Innovative therapies have been developed for amyloidosis with improvement in organ protection, prognosis, and quality of life. These include specific cytoreductive therapies for monoclonal light-chain disease in AL amyloidosis and pharmacologic stabilization or inhibition of transthyretin expression in ATTR amyloidosis. Since the CA underlying amyloidosis is a systemic disease also affecting other organ systems, close interdisciplinary cooperation is crucial for rapid and effective diagnosis and therapy.

Patisiran treatment in patients with hereditary transthyretin-mediated amyloidosis with polyneuropathy after liver transplantation

Hereditary transthyretin-mediated (hATTR) amyloidosis, or ATTRv amyloidosis, is a progressive disease, for which liver transplantation (LT) has been a long-standing treatment. However, disease progression continues post-LT. This Phase 3b, open-label trial evaluated efficacy and safety of patisiran in patients with ATTRv amyloidosis with polyneuropathy progression post-LT. Primary endpoint was median transthyretin (TTR) reduction from baseline. Twenty-three patients received patisiran for 12 months alongside immunosuppression regimens. Patisiran elicited a rapid, sustained TTR reduction (median reduction [Months 6 and 12 average], 91.0%; 95% CI: 86.1%-92.3%); improved neuropathy, quality of life, and autonomic symptoms from baseline to Month 12 (mean change [SEM], Neuropathy Impairment Score, -3.7 [2.7]; Norfolk Quality of Life-Diabetic Neuropathy questionnaire, -6.5 [4.9]; least-squares mean [SEM], Composite Autonomic Symptom Score-31, -5.0 [2.6]); and stabilized disability (Rasch-built Overall Disability Scale) and nutritional status (modified body mass index). Adverse events were mild or moderate; five patients experienced ≥1 serious adverse event. Most patients had normal liver function tests. One patient experienced transplant rejection consistent with inadequate immunosuppression, remained on patisiran, and completed the study. In conclusion, patisiran reduced serum TTR, was well tolerated, and improved or stabilized key disease impairment measures in patients with ATTRv amyloidosis with polyneuropathy progression post-LT (www.clinicaltrials.gov NCT03862807).

Circulating biomarkers in diagnosis and management of cardiac amyloidosis: a review for internist

Cardiac amyloidosis (CA) is due to extracellular myocardial deposition of misfolded proteins resulting in severe cardiac dysfunction and death. The precursors of amyloid fibrils, able of determining a relevant cardiac infiltration, are immunoglobulin-free light chains (AL amyloidosis) and transthyretin (TTR) (both wild and mutated types). The diagnosis of amyloidosis represents a challenge for the clinician given its rarity and its protean clinical presentation, thus an early diagnosis remains a cornerstone for the prognosis of these patients, also in light of the growing available treatments. There is great interest in identifying and applying biomarkers to help diagnose, inform prognosis, guide therapy, and serve as surrogate endpoints in these patients. In AL amyloidosis, biomarkers such as free light chains, natriuretic peptides and troponins are the most extensively studied and validated; they have proved useful in risk stratification, guiding treatment choice and monitoring hematological and organ response. A similar biomarker-based prognostic score is also proposed for ATTR amyloidosis, although studies are small and need to be validated for wild-type and mutant forms.

[de novo hATTR amyloidosis after domino transplantation of a donor's liver: a case report for the use of Patisiran]

Hereditary transthyretin-mediated (hATTR) amyloidosis is a rare, rapidly progressing, and potentially life-threatening disease caused by one of more than 120 mutations in the transthyretin (TTR) gene. As a result of the cumulative amyloid deposits, especially in the peripheral nerves and the heart, the majority of patients develop progressive, peripheral sensorimotor polyneuropathy and biventricular cardiomyopathy over time.Since TTR - and its amyloidogenic variants too - is predominantly synthesized in the liver, early, orthotopic liver transplantation (LTx) is a treatment option that can be used to potentially stop the progression of hATTR amyloidosis.The actual case shows a patient with hepatocellular carcinoma who received the organ of a patient with hATTR as part of a domino liver transplantation. After approximately 10 years, the patient started to develop the characteristic symptoms of the metabolic disorder. Because of a further progression of the amyloidosis, therapy with the RNA interference therapeutic patisiran was initiated, which temporarily halted the progression.

A Rare Case of I127V Heterozygous Transthyretin Amyloidosis With Atypical Transthoracic Echocardiogram Findings Presenting As Upper Extremity Sensorimotor Polyneuropathy

Hereditary transthyretin amyloidosis (hATTR) is a class of disorders with various systemic clinical manifestations, most often cardiac and neurologic in origin. The I127V mutation is a known but uncommon type of hATTR that typically affects males in their sixth or seventh decade of life. We present a case of this rare genetic variant with an atypical presentation of upper, followed by lower extremity sensorimotor polyneuropathy, with an uncharacteristic transthoracic echocardiogram (TTE) pattern but strongly positive pyrophosphate (PYP) scan, confirming the amyloidosis (AL) diagnosis.

Signaling cascades in the failing heart and emerging therapeutic strategies

Chronic heart failure is the end stage of cardiac diseases. With a high prevalence and a high mortality rate worldwide, chronic heart failure is one of the heaviest health-related burdens. In addition to the standard neurohormonal blockade therapy, several medications have been developed for chronic heart failure treatment, but the population-wide improvement in chronic heart failure prognosis over time has been modest, and novel therapies are still needed. Mechanistic discovery and technical innovation are powerful driving forces for therapeutic development. On the one hand, the past decades have witnessed great progress in understanding the mechanism of chronic heart failure. It is now known that chronic heart failure is not only a matter involving cardiomyocytes. Instead, chronic heart failure involves numerous signaling pathways in noncardiomyocytes, including fibroblasts, immune cells, vascular cells, and lymphatic endothelial cells, and crosstalk among these cells. The complex regulatory network includes protein-protein, protein-RNA, and RNA-RNA interactions. These achievements in mechanistic studies provide novel insights for future therapeutic targets. On the other hand, with the development of modern biological techniques, targeting a protein pharmacologically is no longer the sole option for treating chronic heart failure. Gene therapy can directly manipulate the expression level of genes; gene editing techniques provide hope for curing hereditary cardiomyopathy; cell therapy aims to replace dysfunctional cardiomyocytes; and xenotransplantation may solve the problem of donor heart shortages. In this paper, we reviewed these two aspects in the field of failing heart signaling cascades and emerging therapeutic strategies based on modern biological techniques.

Advances in siRNA therapeutics and synergistic effect on siRNA activity using emerging dual ribose modifications

Nucleic acid-based therapeutics that control gene expression have been steadily progressing towards achieving their full clinical potential throughout the last few decades. Rapid progress has been achieved in RNAi-based therapy by optimizing high specificity and gene silencing efficiency using chemically modified siRNAs. Since 2018, four siRNA drugs – patisiran, givosiran, lumasiran, and inclisiran, were approved by the US FDA, providing a testament to the promise of RNAi therapeutics. Despite these promising results, safe and efficient siRNA delivery at the target site remains a major obstacle for efficient siRNA-based therapeutics. In this review, we have outlined the synergistic effects of emerging dual ribose modifications, including 2’,4’- and 2’,5’-modifications, 5’-E/Z-vinylphosphonate, and northern methanocarbacyclic (NMC) modifications that have contributed to drug-like effects in siRNA. These modifications enhance nuclease stability, prolong gene silencing efficiency, improve thermal stability, and exhibit high tissue accumulation. We also highlight the current progress in siRNA clinical trials. This review will help to understand the potential effects of dual ribose modifications and provides alternative ways to use extensive 2’-modifications in siRNA drugs. Moreover, the minimal number of these dual ribose modifications could be sufficient to achieve the desired therapeutic effect. In future, detailed in vivo studies using these dual ribose modifications could help to improve the therapeutic effects of siRNA. Rational design could further open doors for the rapid progress in siRNA therapeutics.

Healthcare resource use associated with the diagnosis of transthyretin amyloidosis cardiomyopathy

OBJECTIVES

Our primary aim was to evaluate the healthcare resource use associated with the diagnosis of transthyretin amyloidosis cardiomyopathy. Second, we aim to assess the effect of the number of diagnostic tests and clinical contact points on the total time and costs between symptom onset and diagnosis defining a quantitative hypothetical optimized diagnostic pathway.

SETTING

Clinical and cost data were collected from patients presenting between 2010 and 2018 in a tertiary referral institution in South London involving two participating hospitals.

PARTICIPANTS

Thirty-eight adult patients with a definite diagnosis of transthyretin amyloidosis cardiomyopathy were included, mostly male (n = 28, 74%) and of African-Caribbean descent (n = 23, 64%). We excluded patients without a confirmed transthyretin amyloidosis cardiomyopathy or those on inotersen, patisiran, or diflunisal at point of referral.

PRIMARY AND SECONDARY OUTCOME MEASURES

The average time between first presentation and final diagnosis, and the cost per patient per month. By comparing to a more optimal clinical pathway towards diagnosis, we considered what could be the theoretical gain in terms of time to diagnosis and financial savings.

RESULTS

The average time between first presentation and final diagnosis was 2.74 years. The average cost per patient per month was higher with progressive heart failure symptoms. A hypothetical optimal pathway reduces time to diagnosis of 1.65 to 1.74 years per patient. The potential financial savings are estimated within the range of £3000 to £4800 per patient.

CONCLUSIONS

Patients diagnosed with transthyretin amyloidosis cardiomyopathy have substantial healthcare resource utilization and costs starting from symptom onset. Higher costs were observed with progression in symptoms and appear linked to a delayed diagnosis. The number of additional diagnostic tests and clinical contact points may contribute to this and could represent a path to explore further for important health and cost savings, with more efficient pathways for these patients to be managed.

An evaluation of the pharmacokinetics of inclisiran in the treatment of atherosclerotic cardiovascular disease

INTRODUCTION

Inclisiran is a small interfering RNA that inhibits hepatic production of proprotein convertase subtilisin/kexin type 9 (PCSK9) which results in reduction of circulating low-density lipoprotein cholesterol (LDL-C). It can be used alone or in combination with statins or other lipid-lowering therapy.

AREAS COVERED

In this article we review the pharmacokinetics, pharmacodynamics and clinical efficacy of inclisiran based on the published literature.

EXPERT OPINION

Inclisiran is a chemically stabilized duplex RNA conjugated with triantennary N-acetylgalactosamine which facilitates rapid and selective liver uptake and the drug is almost entirely removed from the circulation within 24 hours after subcutaneous injection. The duration of action is impressively prolonged and after doses of 300 mg on days one and 90, the dose can be repeated every six months to maintain a durable reduction of LDL-C by about 50%. The efficacy and safety are similar to the monoclonal antibodies targeting PCSK9, evolocumab and alirocumab, and injection site reactions are infrequent and generally mild. The cardiovascular outcome study with inclisiran is ongoing and other long term safety data are keenly awaited. The infrequent dosing regimen offers a major advantage to improve long term compliance and inclisiran may be extensively adopted depending on the cost.

Recent Advances in RNA Therapy and Its Carriers to Treat the Single-Gene Neurological Disorders

The development of new sequencing technologies in the post-genomic era has accelerated the identification of causative mutations of several single gene disorders. Advances in cell and animal models provide insights into the underlining pathogenesis, which facilitates the development and maturation of new treatment strategies. The progress in biochemistry and molecular biology has established a new class of therapeutics—the short RNAs and expressible long RNAs. The sequences of therapeutic RNAs can be optimized to enhance their stability and translatability with reduced immunogenicity. The chemically-modified RNAs can also increase their stability during intracellular trafficking. In addition, the development of safe and high efficiency carriers that preserves the integrity of therapeutic RNA molecules also accelerates the transition of RNA therapeutics into the clinic. For example, for diseases that are caused by genetic defects in a specific protein, an effective approach termed “protein replacement therapy” can provide treatment through the delivery of modified translatable mRNAs. Short interference RNAs can also be used to treat diseases caused by gain of function mutations or restore the splicing aberration defects. Here we review the applications of newly developed RNA-based therapeutics and its delivery and discuss the clinical evidence supporting the potential of RNA-based therapy in single-gene neurological disorders.

Responder analysis for neuropathic impairment and quality-of-life assessment in patients with hereditary transthyretin amyloidosis with polyneuropathy in the NEURO-TTR study

OBJECTIVE

Hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) is a rare disease characterized by rapid neuropathic progression. In pivotal studies of gene-silencing treatments, the modified Neuropathy Impairment Score + 7 tests (mNIS + 7) and Norfolk-Quality of Life (QOL)-Diabetic Neuropathy (DN) questionnaire assessed treatment impact on neuropathic progression. Establishing responder definition (RD) thresholds for these measures would enable evaluation of clinically meaningful treatment benefit.

METHODS

mNIS + 7 and Norfolk-QOL-DN were administered at baseline and week 65 to 165 adults with ATTRv-PN receiving inotersen (n = 106) or placebo (n = 59) in the NEURO-TTR study. Anchor-based approaches for estimating RD thresholds were used for Norfolk QOL-DN, while distribution-based approaches were used for both measures. Responders were patients with a score change < RD, indicating improvement or stabilization (i.e., no clinically meaningful progression). Odds ratios (ORs) and Fisher's exact tests compared proportions of responders by treatment.

RESULTS

The mean RD estimates were 12.2 points and 8.8 points for mNIS + 7 and Norfolk QOL-DN, respectively. The proportions of patients whose change in score indicated improvement or stabilization were statistically significantly larger for inotersen than placebo for all estimated RD thresholds for mNIS + 7 (64-86% responders for inotersen vs. 27-46% for placebo, ORs = 3.8-7.2, ps < 0.001) and Norfolk QOL-DN (66-81% vs. 35-56%, ORs = 2.4-3.6, ps < 0.05).

DISCUSSION

Establishing RD thresholds for these instruments enables evaluation of clinically relevant and individual-level treatment benefit on neuropathic progression. Across RDs estimated using multiple methods, a higher proportion of patients receiving inotersen than placebo showed improved or stabilized neuropathic progression at week 65.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01737398; Date of registration: November 29, 2012.

Suspecting and diagnosing transthyretin amyloid cardiomyopathy (ATTR-CM) in India: An Indian expert consensus

Transthyretin cardiac amyloidosis (ATTR-CM) is a rare and under-recognized disorder characterized by the aggregation of transthyretin-derived insoluble amyloid fibrils in the myocardium. Heterogeneity of symptoms at presentation, makes its diagnosis often delayed. An expert panel gathered on a virtual platform across India to conduct a meeting for developing a guiding tool for ATTR-CM diagnosis. The panel recommended younger age (≥40 years) for suspecting ATTR-CM and thick-walled non-dilated hypokinetic ventricle was considered as one of the important red flags. Electrocardiogram (ECG) and echocardiography (ECHO) findings were recommended as primary tests to raise the suspicion while nuclear scintigraphy and hematological tests were recommended to confirm the diagnosis and rule out amyloid light-chain (AL) amyloidosis. Cardiac magnetic resonance (CMR) and biopsy were recommended in case of ambiguity in the presence of red flags. Considering the lack of expert guidelines in the Indian scenario, a standardized diagnostic algorithm was also proposed.

Future Impact of mRNA Therapy on Cardiovascular Diseases

The silver lining of the recent pandemic was that it accelerated the emergence of messenger ribonucleic acid (mRNA) therapeutics. The great promise of mRNA therapeutics was highlighted by the speed at which the vaccines were created, tested, and proven to be relatively safe and highly effective. There are a wide variety of mRNA therapeutics now under development, and dozens of these are in clinical trials. These therapeutics are generating a major paradigm shift in medical therapy, including the treatment of cardiovascular disease. Most of the cardiovascular mRNA therapies are still in preclinical development, although a phase 2a trial of mRNA therapy for myocardial ischemia has been completed with promising results.¹ The application of mRNA therapies to cardiovascular diseases is virtually limitless, and ongoing work includes mRNA therapies for myocardial ischemia, heart failure, arrhythmias, hypercholesterolemia, and arterial occlusive diseases. In addition, mRNA may be used to enhance cell therapies. In the future, mRNA therapies for cardiovascular disease are destined to supplant some of our current biologics and pharmacotherapies and will be used to treat previously untreatable cardiovascular diseases. Furthermore, mRNA therapies can be personalized, and they can be rapidly generated in current Good Manufacturing Practice facilities with a modest footprint, facilitating the rise of hospital-based regional centers of RNA therapeutics.

Modern Approaches To Cardiovascular Amyloidosis Treatment

Cardiovascular (cardiac) amyloidosis (CA) is a clinical pathology, usually of a geneticallymediated nature, initiated by the precipitation process of the insoluble fibrous protein with β-pleated sheet secondary structure. Such anomalous changes lead to the formation of amyloid fibrils, which may give rise to various forms of amyloidosis. Amyloid formation can be found in various organs and systems, such as cardiovascular system, central and peripheral nervous systems, liver, urinary tract, etc. CA is a rare degenerative disease resulting in congestive cardiac failure and heart arrhythmia with subsequent untimely death. Unfortunately, up to date, the choice of medications for treating amyloidosis is very limited. In this paper, we review clinically used pharmaceutical drugs for CA treatment, along with some delivery systems for such compounds.