Amyloid neuropathies

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.

Peripheral Neuropathy

Peripheral neuropathy is a commonly encountered diagnosis in both neurology and primary care office settings. It is important for primary care providers to identify, characterize, and diagnose patients with neuropathy. This study aims to describe the clinical presentation, diagnostic work up, and treatment options for this entity, as well as the identification of atypical features that should prompt specialized laboratory testing, electrodiagnostic testing, and neurologic consultation.

Neurofilament Light Chains in Systemic Amyloidosis: A Systematic Review

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

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Dapagliflozin treatment and cardiovascular outcome in RBP4/TTRVal30Met (transthyretin cardiac amyloidosis) mice

AIMS

Whether sodium-glucose co-transporter 2 inhibitors are effective for heart failure caused by ATTR-CA (transthyretin cardiac amyloidosis) remains uncertain. The aim of this study is to investigate the cardiovascular prognosis in ATTR-CA mice model with dapagliflozin treatment.

METHODS AND RESULTS

Humanized RBP4/TTRVal50Met and RBP4/TTR mice models were constructed with clustered regularly interspaced short palindromic repeats and associated Cas9 endonuclease (CRISPR-Cas9) techniques and multiple generations breeding. A total of 6 RBP4/TTR mice received placebo treatment, when 12 RBP4/TTRVal50Met received dapagliflozin (1 mg/kg/day, 6 mice) and placebo (6 mice) treatment. Fasting glucose, intraperitoneal glucose tolerance test, and plasma brain natriuretic peptide (BNP) concentration were measured at Day 0, Week 2, and Week 4. BNP, transforming growth factor-beta (TGF-β), collagen type I alpha 1 (COL1A1) protein levels, and Cola1, TGFβ1, TNFα, IL-1β, BNP relative quantities in cardiac, along with cardiac pathology examination including right ventricular collagen percentage, ventricular septum thickness, left ventricular wall thickness, and left ventricular internal diameter were measured at Week 4 after treatment procedure. All 18 mice completed the experiment. The baseline characteristics were balanced among three treatment groups. In placebo-treated mice, the cardiac BNP relative quantity was significantly higher in RBP4/TTRVal50Met mice than RBP4/TTR mice (RBP4[KI/KI], TTR [KI/KI]: 0.72 ± 0.46, RBP4[KI/KI], TTRVal50Met [KI/KI]: 1.44 ± 0.60, P = 0.043), indicating more significant heart failure progression in ATTR-CA mice than normal mice. In ATTR-CA mice, the cardiovascular prognosis measurements including heart failure (plasma BNP concentration and relative quantities of BNP), cardiac inflammation (relative quantities of Cola1, TGFβ1, TNFα, and IL-1β), and pathological changes (right ventricular collagen percentage, ventricular septum thickness, left ventricular wall thickness, and left ventricular internal diameter) were statistically comparable between those under dapagliflozin and placebo treatment.

CONCLUSIONS

Dapagliflozin did not improve cardiovascular prognosis including the progression of heart failure, cardiac inflammation, and pathological changes in ATTR-CA mice compared with placebo. The results of this study were not in support of dapagliflozin's therapeutic effects for ATTR-CA. More pre-clinical and clinical researches to validate these findings and demonstrate the underlying mechanisms are still required.

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.

Differential Diagnosis and Therapeutic Advances in Multiple Myeloma: A Review Article

Multiple myeloma (MM) is a hematologic malignancy characterized by the abnormal clonal proliferation of plasma cells that may result in focal bone lesions, renal failure, anemia, and/or hypercalcemia. Recently, the diagnosis and treatment of MM have evolved due to a better understanding of disease pathophysiology, improved risk stratification, and new treatments. The incorporation of new drugs, including proteasome inhibitors, immunomodulatory drugs, anti-CD38 antibodies and high-dose chemotherapy followed by hematopoietic stem cell transplantation, has resulted in a significant improvement in patient outcomes and QoL. In this review, we summarize differential diagnoses and therapeutic advances in MM.

Evaluation of peripheral nerve involvements in patients with familial Mediterranean fever

Objectives

The aim of this study was to evaluate possible peripheral and autonomic nerve involvement in familial Mediterranean fever (FMF) patients with nerve conduction studies, sympathetic skin response (SSR) and RR interval variability (RRIV).

Patients and methods

The comparative case series was conducted with 76 participants between November 2017 and December 2018. Forty-six FMF patients, [12 with amyloidosis (5 males, 7 females; mean age: 44.7±13.9 years) and 34 without amyloidosis (14 males, 20 females; mean age: 35.9±8.7 years)], and 30 healthy volunteers (11 males, 19 females; mean age: 38.4±10 years) were included in this study. Nerve conduction parameters, SSR latency and amplitude from palmar and plantar responses, and RRIV at rest and deep breathing were studied in all the subjects. Neuropathic symptoms of the patient group were evaluated using the survey of autonomic symptoms scale and the neuropathy disability score.

Results

Nerve conduction studies of the patient group revealed polyneuropathy in seven (15.21%) patients and carpal tunnel syndrome in six (13.04%) patients. The mean amplitudes of SSR measured from the soles were significantly lower than the control group (p=0.041). The mean values of RRIV during rest and hyperventilation were lower in the patient group compared to the control group, but no statistically significant difference was found (p=0.484, p=0.341).

Conclusion

We detected that the prevalence of carpal tunnel syndrome in our patient population (13.04%) was higher than in the general population. Most of the changes in the range of parameters of SSR and RRIV determined in the patient group did not reach statistical significance, suggesting subclinical dysautonomia in FMF patients.

Transthyretin Variant Amyloidosis with a TTR A97D (p.A117D) Mutation Manifesting Remarkable Asymmetric Neuropathy

We herein report a 68-year-old Japanese man with sporadic variant transthyretin (ATTRv) amyloidosis harboring the novel variant A97D (p.A117D) in TTR. He had slow development of asymmetric neuropathy, unintentional weight loss, mild autonomic failure and mild cardiomyopathy. TTR amyloid deposition on the gastric duodenal mucosa was detected. In silico analyses predicted that TTR A97D (p.A117D) altered the structure and function of the TTR protein. ATTRv amyloidosis is often difficult to diagnose in non-endemic regions due to its diverse phenotypes, such as atypical peripheral nerve involvement and a rare family history.

Peritoneal Amyloid as a Presenting Manifestation of AL Amyloid

Amyloid is a systemic disease characterized by extracellular deposition of misfolded protein. Gastrointestinal and peritoneal deposition of light chain (AL) amyloid is an under-recognized manifestation of this systemic disease, usually as a late sequela. Here we present a case of recently diagnosed AL peritoneal amyloid that presented in the context of recurrent, acute onset abdominal discomfort and was found to have bowel obstruction complicated by perforation in the setting of AL-mediated gastrointestinal tract infiltration and dysmotility.

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.

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.

Does [99mTc]-3,3-diphosphono-1,2-propanodicarboxylic acid (DPD) soft tissue uptake allow the identification of patients with the diagnosis of cardiac transthyretin-related (ATTR) amyloidosis with higher risk for polyneuropathy?

BACKGROUND

With the introduction of several drugs for the therapy of transthyretin-related amyloidosis (ATTR) which slow down the disease, early detection of polyneuropathy (PNP) is becoming increasingly of interest. [99mTc]-3,3-Diphosphono-1,2-Propanodicarboxylic Acid (DPD) bone scintigraphy, which is used for the diagnosis of cardiac (c)ATTR, can possibly make an important contribution in the identification of patients at risk for PNP.

METHODS

Fifty patients with cATTR, who underwent both planar whole-body DPD scintigraphy and nerve conduction studies (NCS) were retrospectively evaluated. A subgroup of 22 patients also underwent quantitative SPECT/CT of the thorax from which Standardized Uptake Values (SUVpeak) in the subcutaneous fat tissue of the left axillar region were evaluated.

RESULTS

The Perugini score was significantly increased in patients with cATTR and additional diagnosis of PNP compared to patients without (2.51 ± 0.51 vs 2.13 ± 0.52; P = 0.03). Quantitative SPECT/CT revealed that DPD uptake in the subcutaneous fat of the left axillar region was significantly increased in cATTR patients with compared to patients without (1.36 ± 0.60 vs 0.74 ± 0.52; P = 0.04).

CONCLUSION

This study suggests that DPD bone scintigraphy is a useful tool for identification of patients with cATTR and a risk for PNP due to increased DPD soft tissue uptake.

Role of tubulin post-translational modifications in peripheral neuropathy

Peripheral neuropathy is a common disorder that results from nerve damage in the periphery. The degeneration of sensory axon terminals leads to changes or loss of sensory functions, often manifesting as debilitating pain, weakness, numbness, tingling, and disability. The pathogenesis of most peripheral neuropathies remains to be fully elucidated. Cumulative evidence from both early and recent studies indicates that tubulin damage may provide a common underlying mechanism of axonal injury in various peripheral neuropathies. In particular, tubulin post-translational modifications have been recently implicated in both toxic and inherited forms of peripheral neuropathy through regulation of axonal transport and mitochondria dynamics. This knowledge forms a new area of investigation with the potential for developing therapeutic strategies to prevent or delay peripheral neuropathy by restoring tubulin homeostasis.

RNAi-Based Therapeutics and Novel RNA Bioengineering Technologies

RNA interference (RNAi) provides researchers with a versatile means to modulate target gene expression. The major forms of RNAi molecules, genome-derived microRNAs (miRNAs) and exogenous small interfering RNAs (siRNAs), converge into RNA-induced silencing complexes to achieve posttranscriptional gene regulation. RNAi has proven to be an adaptable and powerful therapeutic strategy where advancements in chemistry and pharmaceutics continue to bring RNAi-based drugs into the clinic. With four siRNA medications already approved by the US Food and Drug Administration (FDA), several RNAi-based therapeutics continue to advance to clinical trials with functions that closely resemble their endogenous counterparts. Although intended to enhance stability and improve efficacy, chemical modifications may increase risk of off-target effects by altering RNA structure, folding, and biologic activity away from their natural equivalents. Novel technologies in development today seek to use intact cells to yield true biologic RNAi agents that better represent the structures, stabilities, activities, and safety profiles of natural RNA molecules. In this review, we provide an examination of the mechanisms of action of endogenous miRNAs and exogenous siRNAs, the physiologic and pharmacokinetic barriers to therapeutic RNA delivery, and a summary of the chemical modifications and delivery platforms in use. We overview the pharmacology of the four FDA-approved siRNA medications (patisiran, givosiran, lumasiran, and inclisiran) as well as five siRNAs and several miRNA-based therapeutics currently in clinical trials. Furthermore, we discuss the direct expression and stable carrier-based, in vivo production of novel biologic RNAi agents for research and development. SIGNIFICANCE STATEMENT: In our review, we summarize the major concepts of RNA interference (RNAi), molecular mechanisms, and current state and challenges of RNAi drug development. We focus our discussion on the pharmacology of US Food and Drug Administration-approved RNAi medications and those siRNAs and miRNA-based therapeutics that entered the clinical investigations. Novel approaches to producing new true biological RNAi molecules for research and development are highlighted.

Characteristics of patients with autonomic dysfunction in the Transthyretin Amyloidosis Outcomes Survey (THAOS)

BACKGROUND

Autonomic dysfunction is common in transthyretin amyloidosis (ATTR amyloidosis), but its frequency, characteristics, and quality-of-life (QoL) impact are not well understood.

METHODS

The Transthyretin Amyloidosis Outcomes Survey (THAOS) is an ongoing, global, longitudinal survey of patients with ATTR amyloidosis, including patients with inherited (ATTRv) and wild-type (ATTRwt) disease and asymptomatic patients with TTR mutations (ClinicalTrials.gov: NCT00628745). In a descriptive analysis, characteristics and Norfolk QoL-DN total (TQoL) scores at enrolment were compared in patients with vs without autonomic dysfunction (analysis cut-off: 1 August 2020).

RESULTS

Autonomic dysfunction occurred in 1181/2922 (40.4%) symptomatic patients, and more commonly in ATTRv (1107/1181 [93.7%]) than ATTRwt (74/1181 [6.3%]) amyloidosis. Time (mean [SD]) from ATTR amyloidosis symptom onset to first autonomic dysfunction symptom was shorter in ATTRv (3.4 [5.7] years) than ATTRwt disease (9.7 [10.4]). In ATTRv disease, patients with vs without autonomic dysfunction had worse QoL (TQoL, 47.3 [33.2] vs 16.1 [18.1]); in ATTRwt disease, those with vs without autonomic dysfunction had similar QoL (23.0 [18.2] vs 19.9 [20.5]).

CONCLUSIONS

Autonomic dysfunction was more common and presented earlier in symptomatic ATTRv than ATTRwt amyloidosis and adversely affected QoL in ATTRv disease. These THAOS findings may aid clinicians in diagnosing and treating patients with ATTR amyloidosis. Trial registration: ClinicalTrials.gov: NCT00628745.

A Study of Familial Amyloid Polyneuropathy Induced by the TTR Val30Leu Mutation in China

INTRODUCTION

Familial amyloid polyneuropathy is currently prevalent worldwide as the transthyretin (TTR) Val30Met mutation, and there are other types of mutations. The purpose of this study was to understand the clinical manifestations, electrophysiological characteristics, and outcomes of hormone-related therapy in patients with the TTR Val30Leu mutation in China.

METHODS

Clinical data were collected from 9 members of a family with the TTR Val30Leu mutation in China, and blood samples of 7 members of the family were sequenced. The electrophysiological examinations of 4 of them were collected and analysed.

RESULTS

A total of 7 people had the TTR gene c.148G>T missense mutation and the TTR protein Val30Leu mutation in this family, and the positive members all had similar symptoms, such as limb paraesthesia and gastrointestinal symptoms. In addition, electrophysiological examination showed abnormal nerve conduction velocity in all 4 patients.

CONCLUSIONS

The clinical manifestations of this mutation involve mainly limb sensory or motor disorders or gastrointestinal symptoms or both, and the electrophysiological examination shows neurogenic damage.

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).

Three patients of transthyretin amyloidosis in a Japanese family with amyloidogenic transthyretin Thr49Ser (p.Thr69Ser) variant

Transthyretin (TTR)-related hereditary amyloidosis (ATTRv) is a rare autosomal dominant disorder that is caused by pathogenic missense mutation of the TTR gene. As of today, more than 150 TTR gene variants have been reported to occur as causal mutations. Herein, we present three familial patients of ATTRv caused by the Thr49Ser (p.Thr69Ser) variant, including their phenotypes and penetrance. The first patient was a 68-year-old woman with a history of carpal tunnel syndrome, who was referred to our department with heart failure symptoms. Echocardiography, ^99mTechnetium (Tc)-pyrophosphate scintigraphy, and myocardial biopsy confirmed her diagnosis as TTR-related amyloidosis. Genetic testing for the TTR gene was performed, which confirmed the presence of a Thr49Ser (p.Thr69Ser) variant. The second patient, a 45-year-old woman, who was the niece of the first patient, presented with dyspnea on exertion. Her clinical manifestations included cardiac symptoms in addition to polyneuropathy. Similarly, myocardial biopsy showed TTR amyloid deposition within cardiac tissues, and TTR gene sequencing detected the presence of a Thr49Ser (p.Thr69Ser) variant. The final patient was a 42-year-old man, who was the nephew of the first patient, presented with numbness in his hands. Abdominal wall fat pad biopsy showed TTR amyloid deposition, and TTR gene sequencing was performed considering the familial history to confirm the presence of Thr49Ser (p.Thr69Ser) variant. No cardiac symptoms or dysfunctions have been observed yet, but imaging has detected TTR amyloid deposition in the heart. The present three patients with Thr49Ser (p.Thr69Ser) variant showed variation in phenotypes including cardiac and neurological manifestations at a fairly young age. In addition, the familial relationship in this report suggested that this variant is highly penetrant. Early genetic diagnosis due to collecting the genetic information from family medical history may be beneficial to improve patient prognosis via early therapeutic intervention.

Facial Palsy, Radiographic and Other Workup Negative: FROWN

Objectives

Slow-onset peripheral facial palsy is far less common than acute-onset peripheral facial palsy and necessitates diagnostic evaluation for benign or malignant tumors or other less common etiologies. In the rare scenario in which no clarifying etiology is discovered following long-term evaluation (no radiographic or hematologic abnormalities and an otherwise unremarkable evaluation), a diagnostic and management dilemma occurs. We present a series of patients with this possible new clinical entity: Facial palsy, Radiographic and Other Workup Negative (FROWN) and propose a management strategy for this diagnosis of exclusion.

Methods

A series of 3,849 patients presenting with facial palsy to a tertiary facial nerve center was retrospectively assessed to identify those with progressive loss of facial function over at least 1 month. Exclusion criteria were history, physical or hematologic findings indicative of known diseases associated with facial palsy, and radiographic studies demonstrating a benign or malignant tumor.

Results

Patients with slow-onset facial palsy constituted 5% (190 patients) of the cohort and were ultimately diagnosed with either a benign or malignant neoplasm or other facial nerve pathology. Fourteen patients with slow-onset facial palsy remained without a diagnosis following long-term evaluation and serial imaging. Eleven patients underwent dynamic facial reanimation surgery and facial nerve and muscle biopsy, with no clear histopathologic diagnosis.

Conclusion

Patients with slow-onset facial palsy with negative radiographic and medical evaluations over several years may be characterized as having FROWN, an idiopathic and as yet poorly understood condition, which appears to be amenable to facial reanimation but requires further investigation as to its pathophysiology.

Hereditary transthyretin-mediated amyloidosis with polyneuropathy: baseline anthropometric, demographic and disease characteristics of patients from a reference center

BACKGROUND

Hereditary transthyretin-mediated (hATTR) amyloidosis with polyneuropathy is a rare, inherited, multisystem, and often fatal disease caused by a variant in transthyretin (TTR) gene. Baseline characteristics of patients, especially anthropometric data, are scarce in the literature, and they are relevant to define effective treatment strategies.

OBJECTIVE

This study aimed to describe baseline demographic, anthropometric, and disease characteristics in a cohort of patients from a reference center in Brazil.

METHODS

Symptomatic patients not previously included in clinical trials and eligible for treatment were enrolled. Ethnicity, state of residence, age, sex, weight, height, body mass index (BMI), TTR variant, and Polyneuropathy Disability Score (PND) at diagnosis were analyzed.

RESULTS

Among the 108 patients enrolled, 58.33% were male, 60.19% were Caucasian, and 83.33% lived in the Southeast region. Mean age was 51.61 (±16.37) years, mean weight was 65.76 (±15.16) kg, mean height was 168.33 (±10.26) cm, and mean BMI was 23.11 (±4.45) kg/m2. The most prevalent variant was V30M (86.11%). Patients with PND score 0 presenting autonomic neuropathy were 14.81%. Patients with PND score I-II and III-IV were 52.78 and 32.41%, respectively. Mean weight and BMI were significantly lower in patients with sensory-motor manifestations.

CONCLUSIONS

This is the largest cohort of patients in Brazil for whom anthropometric characteristics have been described. Baseline demographic, anthropometric, and disease data indicate that delay in diagnosis of hATTR amyloidosis with polyneuropathy is still a problem and that efforts must be made to expedite diagnosis and maximize opportunities for new disease-modifying treatments.

[State of corneal nerve fibers in systemic amyloidosis]

The term systemic amyloidosis unites a group of diseases with a single pathogenetic mechanism involving diffuse deposition of a pathological fibrillar protein (amyloid) in the intercellular space of various organs. Among the systemic forms of amyloidosis, light chain amyloidosis (AL-amyloidosis) occurs most often in clinical practice, while transthyretin amyloidosis (TTR-amyloidosis) is its most common hereditary form. Laser corneal confocal microscopy (CCM) allows for in vivo and non-invasive assessment of the state of corneal nerve fibers (CNF).

PURPOSE

To assess the state of CNF in systemic amyloidosis by confocal microscopy data obtained in vivo.

MATERIAL AND METHODS

The main study group included 16 patients (6 men and 10 women, mean age 60.5±11.6 years) with morphologically confirmed primary AL-amyloidosis, and 14 patients (5 men and 9 women, mean age 59.4±11.3 years) with genetically and morphologically confirmed hereditary TTR-amyloidosis. The control group included 23 healthy volunteers of the same age range without any neurological pathologies. The state of CNF was assessed by in vivo CCM data recorded on the HRT III system and its consequently processing using authors' self-developed program Liner 1.2. The criteria for neuropathy intensity was the degree of CNF tortuosity characterized by coefficients of anisotropy (K_ΔL) and symmetry (K_sym) of CNF orientation.

RESULTS

According to the NIS scale, the manifestations of neuropathy in the subgroup of patients with TTR-amyloidosis were significantly more pronounced compared to AL-amyloidosis patients. The severity of clinical manifestations of neuropathy did not depend on the duration of TTR-amyloidosis and AL-amyloidosis (Spearman R r_s=0.21, p=0.58 and r_s= -0.49, p=0.055, respectively). Changes in the quantitative indicators (a decrease in the anisotropy coefficient and an increase in the symmetry coefficient of the fibers orientation) confirm increased tortuosity of CNF in systemic amyloidosis.

CONCLUSION

The clinical picture of systemic amyloidosis is characterized by polymorphism of neurological manifestations that include various symptoms of damage to the peripheral somatic and autonomic nervous system. In vivo CCM can be used to reveal qualitative and quantitative changes in CNF in patients with systemic amyloidosis. However, statistical unreliability of the identified quantitative changes allows considering the state of CNF in amyloidosis only as a component of the disease monitoring algorithm, but not as a biomarker of the disease.

Expert opinion on monitoring symptomatic hereditary transthyretin-mediated amyloidosis and assessment of disease progression

BACKGROUND

Hereditary transthyretin-mediated amyloidosis, also known as ATTRv amyloidosis (v for variant), is a rare, autosomal dominant, fatal disease, in which systemic amyloid progressively impairs multiple organs, leading to disability and death. The recent approval of disease-modifying therapies offers the hope of stabilization or eventual reversal of disease progression, and yet highlights a lack of disease-management guidance. A multidisciplinary panel of expert clinicians from France and the US came to consensus on monitoring the disease and identifying progression through a clinical opinion questionnaire, a roundtable meeting, and multiple rounds of feedback.

MONITORING DISEASE AND PROGRESSION

A multidisciplinary team should monitor ATTRv amyloidosis disease course by assessing potential target organs at baseline and during follow-up for signs and symptoms of somatic and autonomic neuropathy, cardiac dysfunction and restrictive cardiomyopathy, and other manifestations. Variability in penetrance, symptoms, and course of ATTRv amyloidosis requires that all patients, regardless of variant status, undergo regular and standardized assessment in all these categories. Progression in ATTRv amyloidosis may be indicated by: worsening of several existing quantifiable symptoms or signs; the appearance of a new symptom; or the worsening of a single symptom that results in a meaningful functional impairment.

CONCLUSIONS

We suggest that a multisystem approach to monitoring the signs and symptoms of ATTRv amyloidosis best captures the course of the disease. We hope this work will help form the basis of further, consensus-based guidance for the treatment of ATTRv amyloidosis.

Different phenotypes of transthyretin-associated familial amyloid polyneuropathy due to a mutation in p.Glu109Gln in members of the same family

Transthyretin-associated familial amyloid polyneuropathy (TTR-FAP) is an unusual but life-threatening disease that is autosomal dominant inherited and involves the mutation of the transthyretin (TTR) gene. A total of 26 patients with TTR-FAP and different mutations, including the p.Glu 109Gln mutation (previously annotated p. Glu89Gln), were previously reported in Turkey. Herein, we reported two patients from the same family who had the same p.Glu 109Gln mutation but had different clinical phenotypes. The clinical picture mainly involved polyneuropathy in one patient and cardiac involvement in the other patient. This case report mentions that TTR-FAP can cause different clinical phenotypes, even due to the same mutation and even in the same family.

Neuropathies périphériques associées aux syndromes lymphoprolifératifs : spectre clinique et démarche diagnostique

Lymphoproliferative syndromes (multiple myeloma, Waldenström's disease, chronic lymphocytic leukemia, lymphomas) may be associated with peripheral neuropathies. The mechanism can be dysimmune, associated or not with monoclonal gammopathies; paraneoplastic; infiltrative; or more commonly, iatrogenic or due to vitamin deficiency. The diagnosis can be complex, especially when the neuropathy is the presenting manifestation, requiring a close cooperation between internists and neurologists. The positive diagnosis of the neuropathy is based on a systematic electro-clinical investigation, which specifies the topography and the mechanism of the nerve damage, sometimes reinforced by imaging examinations, in particular, nerve and/or plexus MRI. The imputability of the neuropathy to a lymphoproliferative syndrome is based on a set of arguments including the clinical context (B signs, tumour syndrome), first-line laboratory tests (hemogram, protein electrophoresis, viral serologies, complement), auto-antibodies discussed according to the neuropathy (anti-MAG, anti-gangliosides) and sometimes more invasive examinations (bone marrow or neuro-muscular biopsies).

Advances in Diagnosis and Treatment of Cardiac and Renal Amyloidosis

Diagnoses of amyloidosis are increasing annually, and advances in bone scintigraphy and cardiac MRI accompanied by development of nonbiopsy diagnostic criteria have specifically led to a huge increase in transthyretin amyloidosis cardiomyopathy (ATTR-CM) diagnoses worldwide. Tafamidis use is increasing, and there are several ongoing phase III clinical trials of novel agents that promise to transform the treatment landscape for patients with ATTR-CM. In systemic light chain (AL) amyloidosis, more effective chemotherapeutic agents continue to improve patient outcomes. Accelerating the removal of amyloid deposits to accompany these therapies remains the holy grail. However, in the meantime, early diagnosis is undoubtedly key in improving patient outcomes.

Disease Modifying Treatments for Transthyretin Amyloidosis

ABSTRACT

The transthyretin (TTR) amyloidoses result from misfolding of the protein leading to fibril formation and aggregation as amyloid deposits in predominantly the cardiovascular and nervous systems. Cardiac involvement can manifest as heart failure, arrhythmias, and valvular disease. Neurologic involvement can cause sensorimotor polyneuropathies, mononeuropathies, and dysautonomia. Previously, treatment has focused on management of these symptoms and disease sequelae, with a high rate of mortality due to the absence of disease modifying therapies. In this manuscript, we review novel treatments focusing on three mechanistic pathways: (1) silencing of the TTR gene to suppress production, (2) stabilizing of TTR tetramers to prevent misfolding, or (3) disrupting of existing TTR amyloid fibrils to promote reabsorption.

The Conspicuous Link between Ear, Brain and Heart-Could Neurotrophin-Treatment of Age-Related Hearing Loss Help Prevent Alzheimer's Disease and Associated Amyloid Cardiomyopathy?

Alzheimer's disease (AD), the most common cause of dementia in the elderly, is a neurodegenerative disorder associated with neurovascular dysfunction and cognitive decline. While the deposition of amyloid β peptide (Aβ) and the formation of neurofibrillary tangles (NFTs) are the pathological hallmarks of AD-affected brains, the majority of cases exhibits a combination of comorbidities that ultimately lead to multi-organ failure. Of particular interest, it can be demonstrated that Aβ pathology is present in the hearts of patients with AD, while the formation of NFT in the auditory system can be detected much earlier than the onset of symptoms. Progressive hearing impairment may beget social isolation and accelerate cognitive decline and increase the risk of developing dementia. The current review discusses the concept of a brain-ear-heart axis by which Aβ and NFT inhibition could be achieved through targeted supplementation of neurotrophic factors to the cochlea and the brain. Such amyloid inhibition might also indirectly affect amyloid accumulation in the heart, thus reducing the risk of developing AD-associated amyloid cardiomyopathy and cardiovascular disease.

Feasibility of assessing progression of transthyretin amyloid polyneuropathy using nerve conduction studies: Findings from the Transthyretin Amyloidosis Outcomes Survey (THAOS)

Patients with transthyretin amyloid polyneuropathy (ATTR‐PN) show decreased motor and sensory nerve amplitudes and conduction. Electrophysiological changes over time may be sensitive indicators of progression. This analysis from the Transthyretin Amyloidosis Outcomes Survey (THAOS) assessed longitudinal changes in nerve conduction as signals of neurologic disease progression in patients with hereditary ATTR (ATTRv) amyloidosis. Patients with ATTRv in THAOS with recorded nerve conduction values were included (data cut‐off: January 6, 2020); changes in nerve amplitude and velocity over time were assessed. Patients (n = 1389) were 45.0% male; 80.4% were the Val30Met (p.Val50Met) genotype. Mean (SD) age at enrollment was 43.6 (14.5) years; duration of symptoms was 9.3 (6.4) years. Median (10th, 90th percentile) sural nerve amplitude and velocity was 18.0 (4.9, 35.0) μV and 50.7 (41.0, 57.9) m/s; peroneal conduction was 13.0 (4.4, 27.0) μV and 51.0 (41.7, 59.7) m/s, respectively. Median (10th, 90th percentile) percentage change from baseline in sural nerve amplitude was variable, but generally decreased over time from −7.4 (−43.2, 52.4) at year 1 to −14.4 (−76.9, 46.7) at year 8. Percent change from baseline in sural nerve velocity declined similarly: −0.1 (−14.5, 15.3) at year 1 and − 6.4 (−21.3, 10.5) at year 8. The decline was more pronounced in patients with greater disability at baseline. Similar patterns were observed for the peroneal nerve. These data show an association between nerve amplitudes and velocities and disease severity, suggesting progressive deterioration in nerve conduction may be an indicator of ATTRv amyloidosis disease progression.

Hereditary transthyretin amyloidosis in mainland China: a unicentric retrospective study

OBJECTIVE

This study aims to report the genotypes and phenotypes of hereditary transthyretin amyloidosis (ATTR) in a large Chinese cohort, yet the clinical and genetic profiles of ATTR remain elusive in mainland China.

METHODS

Fifty-four patients with molecularly confirmed ATTR from 39 unrelated families were identified by sequencing the TTR gene. Sural nerve biopsies were performed in 40 of these cases. The clinical and electrophysiological data were retrospectively collected and analyzed.

RESULTS

The male/female ratio was 42:12. The average age of patients at the onset of the disease was 47.8 ± 13.0 years. The late-onset type occurred in 29 cases (53.7%). Twenty-two probands (56.4%) had a family history with ATTR. The initial symptoms were limb paresthesia in 33 cases (61.1%), autonomic dysfunction in 15 cases (27.8%), and blurred vision in 6 cases (11.1%). A total of 22 different TTR mutations were identified, including Val30Met (25.6%) in 10 families in North China and Ala97Ser in 4 families (10.3%) in South China. Electrophysiological studies revealed general sensorimotor axonal polyneuropathy in 33/44 cases (75.0%), mixed neuropathy with axonal and demyelinating impairment features in 9/44 cases (20.5%) and isolated carpal tunnel syndrome in two cases. Sural nerve biopsies revealed positive Congo red staining in 16/40 cases (40.0%).

CONCLUSION

Chinese patients with ATTR exhibited heterogeneous TTR genotypes and clinical phenotypes. Val30Met remains the most common mutation type in mainland China.

Transthyretin Amyloid Cardiomyopathy-Current and Future Therapies

OBJECTIVE

To describe the clinical presentation of transthyretin amyloid cardiomyopathy (ATTR-CM) and discuss current treatments and investigational products and their effect on patient outcomes.

DATA SOURCES

A literature search was performed in PubMed (September 2018 to December 2020) using the following keywords: transthyretin amyloidosis, cardiomyopathy, polyneuropathy and transthyretin amyloid cardiomyopathy, monoclonal light-chain, tafamidis, cardiac amyloidosis, ATTR cardiomyopathy, green tea and inhibition of cardiac amyloidosis, AG10, tolcapone, tolcapone and leptomeningeal ATTR, PRX004, NI006, patisiran, inotersen, vutrisiran, AKCEA-TTR-LRx, and NTLA-2001.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials were evaluated for evidence supporting pharmacology, safety, efficacy, and measured outcomes.

DATA SYNTHESIS

Until 2019, there were no approved treatments for ATTR-CM. Treatment consisted of symptom management and organ transplant. Nonpharmacological and pharmacological treatments focused on the symptoms of heart failure (HF) associated with ATTR-CM. However, there are several emerging therapies recently approved or in development to address the underlying pathophysiology. Treatment classes for ATTR-CM include transthyretin stabilizers, human monoclonal antibodies, gene silencers, and CRISPR/Cas9 gene editing.

RELEVANCE TO PATIENT CARE AND CLINICAL PRACTICE

ATTR-CM is a complex disease in which amyloidosis causes cardiomyopathy. Underdiagnosis is attributed to the clinical presentation being heterogeneous, indistinguishable from HF caused by other etiologies, and the need for invasive testing modalities, including endomyocardial biopsy. Improved diagnostic approaches along with targeted therapies can slow disease progression and enhance patient quality of life.

CONCLUSION

Diagnostic modalities along with biomarker and genetic testing could detect disease earlier and target therapy more accurately. Novel therapies demonstrate potential treatment benefits and can help shape the standard of care for these patients.

Neurofilament light chain, a biomarker for polyneuropathy in systemic amyloidosis

OBJECTIVE

To study serum neurofilament light chain (sNfL) in amyloid light chain (AL) amyloidosis patients with and without polyneuropathy (PNP) and to corroborate previous observations that sNfL is increased in hereditary transthyretin-related (ATTRv) amyloidosis patients with PNP.

METHODS

sNfL levels were assessed retrospectively in patients with AL amyloidosis with and without PNP (AL/PNP+ and AL/PNP-, respectively), patients with ATTRv amyloidosis and PNP (ATTRv/PNP+), asymptomatic transthyretin (TTR) gene mutation carriers (TTRv carriers) and healthy controls. Healthy controls (HC) were age- and sex-matched to both AL/PNP- (HC/AL) and TTRv carriers (HC/TTRv). The single-molecule array (Simoa) assay was used to assess sNfL levels.

RESULTS

sNfL levels were increased both in 10 AL/PNP+ patients (p < .001) and in 10 AL/PNP- patients (p < .005) compared to 10 HC/AL individuals. sNfL levels were higher in AL/PNP+ patients than in AL/PNP- patients (p < .005). sNfL levels were also increased in 15 ATTRv/PNP+ patients, compared to both 15 HC/TTRv (p < .0001) and 15 TTRv carriers (p < .0001). ATTRv/PNP+ patients with progressive PNP (PND-score > I) had the highest sNfL levels compared to patients with early PNP (PND-score I) (p = .05). sNfL levels did not differ between TTRv carriers and HC/TTRv individuals. In the group comprising all healthy controls and in the group of TTRv carriers, sNfL levels correlated with age.

CONCLUSION

sNfL levels are increased in patients with PNP in both AL and ATTRv amyloidosis and are related to severity of PNP in ATTRv amyloidosis. sNfL is a promising biomarker to detect PNP, not only in ATTRv but also in AL amyloidosis.

Pupillometry: An objective test to assess endocular hereditary transthyretin amyloidosis

OBJECTIVE

To automatically study the pupillary light reflex in patients with hereditary transthyretin-associated amyloidosis (hATTR).

METHODS

Prospective cross-sectional observational study in patients with hATTR with unilateral scalloped iris. Pupillary light reflex of scalloped iris eyes (21 eyes) were compared with non-scalloped iris eyes (21 eyes, paired eyes of the same patients) and also with a control group of 20 healthy eyes, using static and dynamic pupillometry with the Metrovision^® MonPack One.

RESULTS

No patient presented evident neurological involvment of the cranial nerves. No significant differences were found in the pupillary diameters under standardized lighting conditions (static pupillometry) among groups. In dynamic pupillometry, the amplitude of contraction, the velocity of contraction and the velocity of dilation were statistically significantly lower in eyes with scalloped iris, comparing both with the contralateral non-scalloped iris eyes (p < 0.001 for all) and with eyes from healthy subjects (p < 0.05 for all).

CONCLUSION

A scalloped iris reflects a more advanced endocular hATTR and it is associated with an altered pupillary light reflex. Pupillometry may be a quick, simple, and portable test to objectively evaluate ocular amyloid deposition in hATTR eyes. Pupillary light reflex may not be reliable to evaluate neurological dysfunction in these patients.

Patient and family experience with transthyretin amyloid cardiomyopathy (ATTR-CM) and polyneuropathy (ATTR-PN) amyloidosis: results of two focus groups

BACKGROUND

Transthyretin amyloidosis, or ATTR, is a progressive and debilitating rare proteopathy generally manifested as either transthyretin amyloid polyneuropathy (ATTR-PN) or transthyretin amyloid cardiomyopathy (ATTR-CM). Irrespective of the clinical presentation, affected patients manage a chronic and life-threatening condition that severely impacts their quality of life. Although the primary symptoms and diagnostic criteria for ATTR are increasingly being discussed in the medical literature, due in large part by continual advances in uncovering disease pathophysiology, there exists a surprising paucity of published data on the patient journey and family experience. In order to address this disparity, two focus groups, one for ATTR-CM and one for ATTR-PN, were convened and asked to describe the diagnostic process, symptoms, and impact on their own quality of life that was experienced from these rare and typically misdiagnosed illnesses.

RESULTS

Patients in both ATTR groups often underwent a long and difficult diagnostic odyssey characterized by seemingly nonspecific physical manifestations resulting in mismanagement and suboptimal care, inadequate interventions, and delays in establishing the correct diagnosis, which was integral to determining the specialized treatment they needed. Collectively, patients with ATTR-CM and patients with ATTR-PN reported a similar number of symptoms, but the type of symptoms varied. The ATTR-CM group identified intolerance to activity, inability to exercise, insomnia and fatigue as the most challenging symptoms. The ATTR-PN group identified fatigue, diarrhea/constipation and sensory deficits as the most difficult symptoms. In general, ATTR was reported to be highly stressful for both patients and their families. Spouses of patients with ATTR-CM were often in a caregiver role and reported experiencing considerable anxiety. Patients with ATTR-PN were stressed not only by the physical consequences of their illness, but also by its effects on their parents and other relatives, as well as concerns about children and grandchildren inheriting the disease-causing mutations associated with ATTR. Despite such challenges, family members are identified as an important resource of coping, motivation, inspiration and support.

CONCLUSIONS

Several steps can be taken to reduce the challenges and burdens of living with ATTR, including increased education for primary care physicians and specialists who unknowingly encounter ATTR, increased access to and ready availability of mental health services and support, and increased engagement with support groups and advocacy organizations. Input from patients and their representatives should guide clinical trials, increase the availability of genetic testing, and generate natural history and qualitative studies detailing patients' experience. Although each recommendation is impactful in itself, taken together they would jointly facilitate a shortened and ameliorated patient journey through more timely diagnosis and greater access to personalized medical care.

Updates in the Diagnosis and Management of AL Amyloidosis

PURPOSE OF REVIEW

Light chain (AL) amyloidosis is an insidious progressive disease which results in significant morbidity and inevitable mortality if not diagnosed and treated promptly. This review will highlight recent developments and summarize critical clinical points and updated practice changes for the clinician in 2020.

RECENT FINDINGS

Comparative analyses of staging systems, updated prognostic tools, and treatment response criteria now allow for improved patient stratification and treatment decisions; the role of minimal residual disease in response assessment is still being assessed. Clinical and genetic predictors for long-term survivors have been highlighted. Standard-of-care front-line bortezomib and the integration of anti-CD38 monoclonal antibodies in the relapsed disease have transformed treatment approach in recent years. Various clinical trials in the pipeline include novel anti-plasma cell therapies and therapies directed against amyloid deposits which promise to further advance the treatment landscape. Diagnosis, response assessment, and treatment paradigms for AL amyloidosis have evolved significantly in the past 15 years, translating into superior outcomes and increased chances of long-term survival for AL amyloidosis.

DISCOVERY: prevalence of transthyretin (TTR) mutations in a US-centric patient population suspected of having cardiac amyloidosis

BACKGROUND

Hereditary transthyretin-mediated amyloidosis (hATTR amyloidosis) is a multisystem disease that presents with polyneuropathy and/or cardiomyopathy.

METHODS

DISCOVERY, a multicenter screening study, enrolled patients with clinically suspected cardiac amyloidosis to determine the frequency of transthyretin (TTR) mutations and assess disease characteristics.

RESULTS

Of 1007 patients, the majority were from the US (84%), Black/African American (56%), male (63%), and with a mean (standard deviation) age of 65 (13) years. Among 1001 patients with genotyping results, 74 (7%) had a pathogenic TTR mutation (71/836 [8%] from the US). Val122Ile was the most common mutation, found in 11% of Black/African American patients overall; Black/African American ethnicity was an independent predictor of having a pathogenic TTR mutation. Additional independent predictors of such mutations in the total population and Black/African American group were interventricular septum thickness, low electrocardiogram voltage, and age.

CONCLUSIONS

Pathogenic TTR mutations occurred in 8% of US patients with suspected cardiac amyloidosis. Most mutations were Val122Ile, almost exclusively found in Black/African American patients. Disease often remains undetected until advanced and difficult to treat, therefore, clinicians should assess at-risk patients for hATTR amyloidosis as early as possible.

Neurofilament Light Chain as a Biomarker of Hereditary Transthyretin-Mediated Amyloidosis

OBJECTIVE

To identify changes in the proteome associated with onset and progression of hereditary transthyretin-mediated (hATTR) amyloidosis, also known as ATTRv amyloidosis, we performed an observational, case-controlled study that compared proteomes of patients with ATTRv amyloidosis and healthy controls.

METHODS

Plasma levels of >1,000 proteins were measured in patients with ATTRv amyloidosis with polyneuropathy who received either placebo or patisiran in a Phase 3 study of patisiran (APOLLO), and in healthy controls. The effect of patisiran on the time profile of each protein was determined by linear mixed model at 0, 9, and 18 months. Neurofilament light chain (NfL) was further assessed with an orthogonal quantitative approach.

RESULTS

Levels of 66 proteins were significantly changed with patisiran vs placebo, with NfL change most significant (p < 10^-20). Analysis of changes in protein levels demonstrated that the proteome of patients treated with patisiran trended toward that of healthy controls at 18 months. Healthy controls' NfL levels were 4-fold lower than in patients with ATTRv amyloidosis with polyneuropathy (16.3 pg/mL vs 69.4 pg/mL, effect -53.1 pg/mL [95% confidence interval -60.5 to -45.9]). NfL levels at 18 months increased with placebo (99.5 pg/mL vs 63.2 pg/mL, effect 36.3 pg/mL [16.5-56.1]) and decreased with patisiran treatment (48.8 pg/mL vs 72.1 pg/mL, effect -23.3 pg/mL [-33.4 to -13.1]) from baseline. At 18 months, improvement in modified Neuropathy Impairment Score +7 score after patisiran treatment significantly correlated with reduced NfL (R = 0.43 [0.29-0.55]).

CONCLUSIONS

Findings suggest that NfL may serve as a biomarker of nerve damage and polyneuropathy in ATTRv amyloidosis, enable earlier diagnosis of patients with ATTRv amyloidosis, and facilitate monitoring of disease progression.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that NfL levels may enable earlier diagnosis of polyneuropathy in patients with ATTRv amyloidosis and facilitate monitoring of disease progression.

The Bioequivalence of Tafamidis 61-mg Free Acid Capsules and Tafamidis Meglumine 4 × 20-mg Capsules in Healthy Volunteers

Tafamidis, a non-nonsteroidal anti-inflammatory benzoxazole derivative, acts as a transthyretin (TTR) stabilizer to slow progression of TTR amyloidosis (ATTR). Tafamidis meglumine, available as 20-mg capsules, is approved in more than 40 countries worldwide for the treatment of adults with early-stage symptomatic ATTR polyneuropathy. This agent, administered as an 80-mg, once-daily dose (4 × 20-mg capsules), is approved in the United States, Japan, Canada, and Brazil for the treatment of hereditary and wild-type ATTR cardiomyopathy in adults. An alternative single solid oral dosage formulation (tafamidis 61-mg free acid capsules) was developed and introduced for patient convenience (approved in the United States, United Arab Emirates, and European Union). In this single-center, open-label, randomized, 2-period, 2-sequence, crossover, multiple-dose phase 1 study, the rate and extent of absorption were compared between tafamidis 61-mg free acid capsules (test) and tafamidis meglumine 80-mg (4 × 20-mg) capsules (reference) after 7 days of repeated oral dosing under fasted conditions in 30 healthy volunteers. Ratios of adjusted geometric means (90%CI) for the test/reference formulations were 102.3 (98.0-106.8) for area under the concentration-time profile over the dosing interval and 94.1 (89.1-99.4) for the maximum observed concentration, satisfying prespecified bioequivalence acceptance criteria (90%CI, 80-125). Both tafamidis regimens had an acceptable safety/tolerability profile in this population.

Toxin-Induced Neuropathies

Peripheral neuropathies secondary to neurotoxicants are frequently considered but can be difficult to diagnose. Accurate diagnosis is important to avoid unnecessary testing, prevent further exposure, and initiate treatment when available. This article reviews key features of some of the more common or representative toxic neuropathies, including those caused by occupational and environmental exposure, medications, and chemotherapeutic agents.

Proliferative and Nonproliferative Lesions of the Rat and Mouse Central and Peripheral Nervous Systems: New and Revised INHAND Terms

Harmonization of diagnostic terminology used during the histopathologic analysis of rodent tissue sections from nonclinical toxicity studies will improve the consistency of data sets produced by laboratories located around the world. The INHAND Project (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) is a cooperative enterprise of 4 major societies of toxicologic pathology to develop a globally accepted standard vocabulary for proliferative and nonproliferative lesions in rodents. A prior manuscript (Toxicol Pathol 2012;40[4 Suppl]:87S-157S) defined multiple diagnostic terms for toxicant-induced lesions, common spontaneous and age-related changes, and principal confounding artifacts in the rat and mouse central nervous system (CNS) and peripheral nervous system (PNS). The current article defines 9 new diagnostic terms and updates 2 previous terms for findings in the rodent CNS and PNS, the need for which has become evident in the years since the publication of the initial INHAND nomenclature for findings in rodent neural tissues. The nomenclature presented in this document is also available electronically on the Internet at the goRENI website (http://www.goreni.org/).

Transthyretin-stabilising mutation T119M is not associated with protection against vascular disease or death in the UK Biobank

Background: Destabilised transthyretin (TTR) can result in the progressive, fatal disease transthyretin-mediated (ATTR) amyloidosis. A stabilising TTR mutation, T119M, is the basis for a therapeutic strategy to reduce destabilised TTR. Recently, T119M was associated with extended lifespan and lower risk of cerebrovascular disease in a Danish cohort. We aimed to determine whether this finding could be replicated in the UK Biobank.Methods: TTR T119M carriers were identified in the UK Biobank, a large prospective cohort of ∼500,000 individuals. Association between T119M genotype and inpatient diagnosis of vascular disease, cardiovascular disease, cerebrovascular disease, and mortality was analysed.Results: Frequency of T119M within the white UK Biobank population (n = 337,148) was 0.4%. Logistic regression comparing T119M carriers to non-carriers found no association between T119M and vascular disease (odds ratio [OR] = 1.08; p = .27), cardiovascular disease (OR = 1.08; p = .31), cerebrovascular disease (OR = 1.1; p = .42), or death (OR = 1.2; p = .06). Cox proportional hazards regression showed similar results (hazard ratio >1, p>.05). Age at death and vascular disease diagnosis were similar between T119M carriers and non-carriers (p = .12 and p = .38, respectively).Conclusions: There was no association between the TTR T119M genotype and risk of vascular disease or death in a large prospective cohort study, indicating that TTR tetramer stabilisation through T119M is not protective in this setting.

Quality of life outcomes in APOLLO, the phase 3 trial of the RNAi therapeutic patisiran in patients with hereditary transthyretin-mediated amyloidosis

Introduction: Hereditary transthyretin-mediated (hATTR) amyloidosis is a rare, fatal, multisystem disease leading to deteriorating quality of life (QOL). The impact of patisiran on QOL in patients with hATTR amyloidosis with polyneuropathy from the phase 3 APOLLO study (NCT01960348) is evaluated.Methods: Patients received either patisiran 0.3 mg/kg (n = 148) or placebo (n = 77) intravenously once every three weeks for 18 months. Multiple measures were used to assess varying aspects of QOL.Results: At 18 months, compared with placebo, patisiran improved Norfolk Quality of Life-Diabetic Neuropathy (Norfolk QOL-DN) score; (least squares [LS] mean difference: -21.1; p = 1.10 × 10^-10; improved across all domains), EuroQoL 5-dimensions 5-levels (LS mean difference: 0.2; p = 1.4 × 10^-12), EuroQoL-visual analog scale (LS mean difference: 9.5; p=.0004), Rasch-built Overall Disability Scale (LS mean difference: 9.0; p = 4.07 × 10^-16) and Composite Autonomic Symptom Score-31(COMPASS-31; LS mean difference: -7.5; p=.0008). Placebo-treated patients experienced rapid QOL deterioration; treatment effects for patisiran were observed as early as 9 months. At 18 months, patisiran improved Norfolk QOL-DN total score and three individual domains as well as COMPASS-31 total scores relative to baseline. Consistent benefits were also observed in the cardiac subpopulation.Conclusion: The benefits of patisiran across all QOL measures and the rapid deterioration observed with placebo, highlight the urgency in early treatment for patients with hATTR amyloidosis with polyneuropathy.

Neuromuscular Mimics of Entrapment Neuropathies of Upper Extremities

Introduction: Carpal tunnel syndrome and ulnar neuropathy are such common maladies affecting the upper extremties that they often become the default diagnosis when patients complain of numbness, pain, or weakness of the hands. While often correct, there are a number of other conditions that can also cause sensory or motor loss of the hands, which should be considered when appropriate, as they can mimic upper extremity entrapment syndromes. Methods: In this review, we will discuss such mimics, including Charcot-Marie-Tooth disease, multifocal motor neuropathy, hereditary neuropathy with pressure palsies, mononeuropathy multiplex, Lewis-Sumner syndrome, brachial plexitis (Parsonage-Turner syndrome), myotonic dystrophy, inclusion body myopathy, and distal myopathy of Welander. We will discuss the clinical presentation, as well as diagnostic testing, treatment (if available), and prognosis. Conclusion: The objective is to provide a differential diagnosis for those patients who do not fit well clinically or respond to usual therapy for entrapment neuropathy of the upper extremities.