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Nucleic Acids Research Dec 2020One hallmark of trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNAs is the remarkable durability of silencing that can persist for months in preclinical species...
One hallmark of trivalent N-acetylgalactosamine (GalNAc)-conjugated siRNAs is the remarkable durability of silencing that can persist for months in preclinical species and humans. Here, we investigated the underlying biology supporting this extended duration of pharmacological activity. We found that siRNA accumulation and stability in acidic intracellular compartments is critical for long-term activity. We show that functional siRNA can be liberated from these compartments and loaded into newly generated Argonaute 2 protein complexes weeks after dosing, enabling continuous RNAi activity over time. Identical siRNAs delivered in lipid nanoparticles or as GalNAc conjugates were dose-adjusted to achieve similar knockdown, but only GalNAc-siRNAs supported an extended duration of activity, illustrating the importance of receptor-mediated siRNA trafficking in the process. Taken together, we provide several lines of evidence that acidic intracellular compartments serve as a long-term depot for GalNAc-siRNA conjugates and are the major contributor to the extended duration of activity observed in vivo.
Topics: Acetylgalactosamine; Animals; Argonaute Proteins; Asialoglycoprotein Receptor; Biological Transport; Drug Carriers; Drug Stability; Female; Gene Silencing; Glycoconjugates; Hepatocytes; Humans; Hydrogen-Ion Concentration; Liver; Mice; Mice, Inbred C57BL; Nanoparticles; Prealbumin; RNA, Small Interfering; Time Factors
PubMed: 32808038
DOI: 10.1093/nar/gkaa670 -
Circulation Jul 2020Transthyretin amyloid cardiomyopathy (ATTR-CM) results in a restrictive cardiomyopathy caused by extracellular deposition of transthyretin, normally involved in the... (Review)
Review
Transthyretin amyloid cardiomyopathy (ATTR-CM) results in a restrictive cardiomyopathy caused by extracellular deposition of transthyretin, normally involved in the transportation of the hormone thyroxine and retinol-binding protein, in the myocardium. Enthusiasm about ATTR-CM has grown as a result of 3 simultaneous areas of advancement: Imaging techniques allow accurate noninvasive diagnosis of ATTR-CM without the need for confirmatory endomyocardial biopsies; observational studies indicate that the diagnosis of ATTR-CM may be underrecognized in a significant proportion of patients with heart failure; and on the basis of elucidation of the mechanisms of amyloid formation, therapies are now approved for treatment of ATTR-CM. Because therapy for ATTR-CM may be most effective when administered before significant cardiac dysfunction, early identification of affected individuals with readily available noninvasive tests is essential. This scientific statement is intended to guide clinical practice and to facilitate management conformity by covering current diagnostic and treatment strategies, as well as unmet needs and areas of active investigation in ATTR-CM.
Topics: Algorithms; Alleles; Amyloidosis; Animals; Biomarkers; Cardiomyopathies; Clinical Decision-Making; Disease Management; Disease Susceptibility; Gene Silencing; Genetic Predisposition to Disease; Genotype; Heart Function Tests; Humans; Magnetic Resonance Imaging; Molecular Diagnostic Techniques; Prealbumin
PubMed: 32476490
DOI: 10.1161/CIR.0000000000000792 -
Journal of Neurology, Neurosurgery, and... Jun 2022Hereditary transthyretin amyloidosis (ATTRv) is a severe, adult-onset autosomal dominant inherited systemic disease predominantly affecting the peripheral and autonomic... (Review)
Review
Hereditary transthyretin amyloidosis (ATTRv) is a severe, adult-onset autosomal dominant inherited systemic disease predominantly affecting the peripheral and autonomic nervous system, heart, kidney and the eyes. ATTRv is caused by mutations of the transthyretin (TTR) gene, leading to extracellular deposition of amyloid fibrils in multiple organs including the peripheral nervous system. Typically, the neuropathy associated with ATTRv is characterised by a rapidly progressive and disabling sensorimotor axonal neuropathy with early small-fibre involvement. Carpal tunnel syndrome and cardiac dysfunction frequently coexist as part of the ATTRv phenotype. Although awareness of ATTRv polyneuropathy among neurologists has increased, the rate of misdiagnosis remains high, resulting in significant diagnostic delays and accrued disability. A timely and definitive diagnosis is important, given the emergence of effective therapies which have revolutionised the management of transthyretin amyloidosis. TTR protein stabilisers diflunisal and tafamidis can delay the progression of the disease, if treated early in the course. Additionally, TTR gene silencing medications, patisiran and inotersen, have resulted in up to 80% reduction in TTR production, leading to stabilisation or slight improvement of peripheral neuropathy and cardiac dysfunction, as well as improvement in quality of life and functional outcomes. The considerable therapeutic advances have raised additional challenges, including optimisation of diagnostic techniques and management approaches in ATTRv neuropathy. This review highlights the key advances in the diagnostic techniques, current and emerging management strategies, and biomarker development for disease progression in ATTRv.
Topics: Amyloid Neuropathies, Familial; Heart Diseases; Humans; Polyneuropathies; Prealbumin; Quality of Life
PubMed: 35256455
DOI: 10.1136/jnnp-2021-327909 -
ESC Heart Failure Dec 2019Transthyretin cardiac amyloidosis (ATTR-CA) demonstrates progressive, potentially fatal, and infiltrative cardiomyopathy caused by extracellular deposition of... (Review)
Review
Transthyretin cardiac amyloidosis (ATTR-CA) demonstrates progressive, potentially fatal, and infiltrative cardiomyopathy caused by extracellular deposition of transthyretin-derived insoluble amyloid fibrils in the myocardium. Two distinct types of transthyretin (wild type or variant) become unstable, and misfolding forms aggregate, resulting in amyloid fibrils. ATTR-CA, which has previously been underrecognized and considered to be rare, has been increasingly recognized as a cause of heart failure with preserved ejection fraction among elderly persons. With the advanced technology, the diagnostic tools have been improving for cardiac amyloidosis. Recently, the efficacy of several disease-modifying agents focusing on the amyloidogenic process has been demonstrated. ATTR-CA has been changing from incurable to treatable. Nevertheless, there are still no prognostic improvements due to diagnostic delay or misdiagnosis because of phenotypic heterogeneity and co-morbidities. Thus, it is crucial for clinicians to be aware of this clinical entity for early diagnosis and proper treatment. In this mini-review, we focus on recent advances in diagnosis and treatment of ATTR-CA.
Topics: Aged; Amyloid; Amyloidosis; Cardiomyopathies; Female; Heart; Heart Failure; Humans; Male; Middle Aged; Myocardium; Prealbumin
PubMed: 31553132
DOI: 10.1002/ehf2.12518 -
European Journal of Heart Failure Feb 2021Tafamidis is an effective treatment for transthyretin amyloid cardiomyopathy (ATTR-CM) in the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT). While... (Randomized Controlled Trial)
Randomized Controlled Trial
AIMS
Tafamidis is an effective treatment for transthyretin amyloid cardiomyopathy (ATTR-CM) in the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT). While ATTR-ACT was not designed for a dose-specific assessment, further analysis from ATTR-ACT and its long-term extension study (LTE) can guide determination of the optimal dose.
METHODS AND RESULTS
In ATTR-ACT, patients were randomized (2:1:2) to tafamidis 80 mg, 20 mg, or placebo for 30 months. Patients completing ATTR-ACT could enrol in the LTE (with placebo-treated patients randomized to tafamidis 80 or 20 mg; 2:1) and all patients were subsequently switched to high-dose tafamidis. All-cause mortality was assessed in ATTR-ACT combined with the LTE (median follow-up 51 months). In ATTR-ACT, the combination of all-cause mortality and cardiovascular-related hospitalizations over 30 months was significantly reduced with tafamidis 80 mg (P = 0.0030) and 20 mg (P = 0.0048) vs. placebo. All-cause mortality vs. placebo was reduced with tafamidis 80 mg [Cox hazards model (95% confidence interval): 0.690 (0.487-0.979), P = 0.0378] and 20 mg [0.715 (0.450-1.137), P = 0.1564]. The mean (standard error) change in N-terminal pro-B-type natriuretic peptide from baseline to Month 30 was -1170.51 (587.31) (P = 0.0468) with tafamidis 80 vs. 20 mg. In ATTR-ACT combined with the LTE there was a significantly greater survival benefit with tafamidis 80 vs. 20 mg [0.700 (0.501-0.979), P = 0.0374]. Incidence of adverse events in both tafamidis doses were comparable to placebo.
CONCLUSION
Tafamidis, both 80 and 20 mg, effectively reduced mortality and cardiovascular-related hospitalizations in patients with ATTR-CM. The longer-term survival data and the lack of dose-related safety concerns support tafamidis 80 mg as the optimal dose.
CLINICAL TRIAL REGISTRATION
ClinicalTrials.gov NCT01994889; NCT02791230.
Topics: Amyloid Neuropathies, Familial; Benzoxazoles; Cardiomyopathies; Heart Failure; Humans; Prealbumin
PubMed: 33070419
DOI: 10.1002/ejhf.2027 -
Advances in Clinical and Experimental... Oct 2022Heart failure with preserved ejection fraction (HFpEF) is an increasingly widespread medical condition, with excessive morbidity and mortality. Recently, for the first... (Review)
Review
Heart failure with preserved ejection fraction (HFpEF) is an increasingly widespread medical condition, with excessive morbidity and mortality. Recently, for the first time in HFpEF, a reduction in the primary composite outcome of cardiovascular death or HF hospitalization was shown with empagliflozin. The failure of previous clinical trials in HFpEF might have resulted from suboptimal patient selection and inclusion of patients without "true" or clinically significant HFpEF. Another important factor might be the heterogeneity of HFpEF, and thus there is a growing interest in HFpEF phenotyping. This phenotyping can be based on clinical presentation (e.g., subtypes with predominant atrial fibrillation, obesity, pulmonary hypertension and right ventricular failure, coronary artery disease (CAD), or noncardiac comorbidities), but also on HFpEF etiology. Specific therapies, such as tafamidis in transthyretin-related amyloidosis (ATTR) or mavacamten in hypertrophic cardiomyopathy, have demonstrated their efficacy. However, pathomechanisms leading to the development of different phenotypes of HFpEF seem more complex and subtle. Machine learning and neural network models might help identify specific subgroups within the HFpEF population that either cluster patients with similar genetic, biochemical, echocardiographic or clinical characteristics, or respond similarly to a given treatment. Herein, we review different approaches to HFpEF phenotyping and present some distinct HFpEF subtypes.
Topics: Humans; Heart Failure; Stroke Volume; Prealbumin; Prognosis; Echocardiography; Ventricular Function, Left
PubMed: 35581935
DOI: 10.17219/acem/149728 -
The New England Journal of Medicine Oct 2023Transthyretin amyloidosis, also called ATTR amyloidosis, is associated with accumulation of ATTR amyloid deposits in the heart and commonly manifests as progressive... (Randomized Controlled Trial)
Randomized Controlled Trial
BACKGROUND
Transthyretin amyloidosis, also called ATTR amyloidosis, is associated with accumulation of ATTR amyloid deposits in the heart and commonly manifests as progressive cardiomyopathy. Patisiran, an RNA interference therapeutic agent, inhibits the production of hepatic transthyretin.
METHODS
In this phase 3, double-blind, randomized trial, we assigned patients with hereditary, also known as variant, or wild-type ATTR cardiac amyloidosis, in a 1:1 ratio, to receive patisiran (0.3 mg per kilogram of body weight) or placebo once every 3 weeks for 12 months. A hierarchical procedure was used to test the primary and three secondary end points. The primary end point was the change from baseline in the distance covered on the 6-minute walk test at 12 months. The first secondary end point was the change from baseline to month 12 in the Kansas City Cardiomyopathy Questionnaire-Overall Summary (KCCQ-OS) score (with higher scores indicating better health status). The second secondary end point was a composite of death from any cause, cardiovascular events, and change from baseline in the 6-minute walk test distance over 12 months. The third secondary end point was a composite of death from any cause, hospitalizations for any cause, and urgent heart failure visits over 12 months.
RESULTS
A total of 360 patients were randomly assigned to receive patisiran (181 patients) or placebo (179 patients). At month 12, the decline in the 6-minute walk distance was lower in the patisiran group than in the placebo group (Hodges-Lehmann estimate of median difference, 14.69 m; 95% confidence interval [CI], 0.69 to 28.69; P = 0.02); the KCCQ-OS score increased in the patisiran group and declined in the placebo group (least-squares mean difference, 3.7 points; 95% CI, 0.2 to 7.2; P = 0.04). Significant benefits were not observed for the second secondary end point. Infusion-related reactions, arthralgia, and muscle spasms occurred more often among patients in the patisiran group than among those in the placebo group.
CONCLUSIONS
In this trial, administration of patisiran over a period of 12 months resulted in preserved functional capacity in patients with ATTR cardiac amyloidosis. (Funded by Alnylam Pharmaceuticals; APOLLO-B ClinicalTrials.gov number, NCT03997383.).
Topics: Humans; Cardiomyopathies; Prealbumin; RNA, Small Interfering; Amyloidosis, Familial; Liver; Double-Blind Method; Amyloidosis
PubMed: 37888916
DOI: 10.1056/NEJMoa2300757 -
Circulation Nov 2022Diagnostic and therapeutic advances have led to much greater awareness of transthyretin cardiac amyloidosis (ATTR-CA). We aimed to characterize changes in the clinical... (Observational Study)
Observational Study
BACKGROUND
Diagnostic and therapeutic advances have led to much greater awareness of transthyretin cardiac amyloidosis (ATTR-CA). We aimed to characterize changes in the clinical phenotype of patients diagnosed with ATTR-CA over the past 20 years.
METHODS
This is a retrospective observational cohort study of all patients referred to the National Amyloidosis Centre (2002-2021) in whom ATTR-CA was a differential diagnosis.
RESULTS
We identified 2995 patients referred with suspected ATTR-CA, of whom 1967 had a diagnosis of ATTR-CA confirmed. Analysis by 5-year periods revealed an incremental increase in referrals, with higher proportions of patients having been referred after bone scintigraphy and cardiac magnetic resonance imaging (2% versus 34% versus 51% versus 55%, chi-square <0.001). This was accompanied by a greater number of ATTR-CA diagnoses, predominantly of the wild-type nonhereditary form, which is now the most commonly diagnosed form of ATTR-CA (0% versus 54% versus 67% versus 66%, chi-square <0.001). Over time, the median duration of associated symptoms before diagnosis fell from 36 months between 2002 and 2006 to 12 months between 2017 and 2021 (Mann-Whitney <0.001), and a greater proportion of patients had early-stage disease at diagnosis across the 5-year periods (National Amyloidosis Centre stage 1: 34% versus 42% versus 44% versus 53%, chi-square <0.001). This was associated with more favorable echocardiographic parameters of structure and function, including lesser interventricular septal thickness (18.0±3.8 mm versus 17.2±2.6 mm versus 16.9±2.3 mm versus 16.6±2.4 mm, =0.01) and higher left ventricular ejection fraction (46.0%±8.9% versus 46.8%±11.0% versus 47.8%±11.0% versus 49.5%±11.1%, <0.001). Mortality decreased progressively during the study period (2007-2011 versus 2012-2016: hazard ratio, 1.57 [95% CI, 1.31-1.89], <0.001; and 2012-2016 versus 2017-2021: hazard ratio, 1.89 [95% CI, 1.55-2.30], <0.001). The proportion of patients enrolled into clinical trials and prescribed disease-modifying therapy increased over the 20-year period, but even when censoring at the trial or medication start date, year of diagnosis remained a significant predictor of mortality (2012-2016 versus 2017-2021: hazard ratio, 1.05 [95% CI, 1.03-1.07], <0.001).
CONCLUSIONS
There has been a substantial increase in ATTR-CA diagnoses, with more patients being referred after local advanced cardiac imaging. Patients are now more often diagnosed at an earlier stage of the disease, with substantially lower mortality. These changes may have important implications for initiation and outcome of therapy and urgently need to be factored into clinical trial design.
Topics: Humans; Amyloid Neuropathies, Familial; Cardiomyopathies; Stroke Volume; Cohort Studies; Ventricular Function, Left; Prealbumin
PubMed: 36325894
DOI: 10.1161/CIRCULATIONAHA.122.060852 -
ESC Heart Failure Aug 2023Tafamidis improves prognosis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). However, real-world data on the therapeutic effect of tafamidis are... (Observational Study)
Observational Study
AIMS
Tafamidis improves prognosis in patients with transthyretin amyloid cardiomyopathy (ATTR-CM). However, real-world data on the therapeutic effect of tafamidis are lacking. This study aimed to evaluate the clinical course, outcomes, and effectivity monitoring of the therapeutic effect of tafamidis in patients with ATTR-CM.
METHODS AND RESULTS
This is a single-centre, retrospective observational study. We evaluated the clinical characteristics and outcomes in 125 consecutive patients with wild-type ATTR-CM (ATTRwt-CM) treated with tafamidis (treatment group) and 55 untreated patients (treatment-naïve group). We monitored the therapeutic effect of tafamidis for 12 months by evaluating serial cardiac biomarker and imaging findings. The treatment group had significantly more favourable outcome in all-cause mortality and hospitalization due to heart failure than the treatment-naïve group in both the entire cohort (P < 0.01) and the propensity score-matched cohort (P < 0.05). Kaplan-Meier survival curves showed that tafamidis treatment significantly reduced all-cause mortality (P = 0.03, log-rank test), with the curves diverging after approximately 18 months of treatment in the propensity score-matched cohort. On inverse probability of treatment weighting analysis, tafamidis treatment showed a reduced all-cause mortality [hazard ratio (HR), 0.31; 95% confidence interval (CI), 0.11-0.93; P = 0.04]. High-sensitivity cardiac troponin T (hs-cTnT) > 0.05 ng/mL, B-type natriuretic peptide (BNP) > 250 pg/mL, and estimated glomerular filtration rate (eGFR) < 45 mL/min/1.73 m scored 1 point each. Multivariate logistic regression analysis revealed that a high score (2-3 points) was a significantly poor prognostic factor of composite clinical outcomes, including all-cause death and hospitalization for heart failure (HR, 1.55; 95% CI, 1.22-1.98; P < 0.01) for patients in the treatment group. After 12 months of tafamidis treatment, hs-cTnT levels decreased significantly [0.054 (0.036-0.082) vs. 0.044 (0.033-0.076); P = 0.002], with no significant changes in BNP levels, echocardiographic parameters, native T1 value, and extracellular volume fraction on cardiac magnetic resonance imaging.
CONCLUSIONS
The prognosis of patients with ATTRwt-CM treated with tafamidis was more favourable than that of untreated patients. Patient stratification combined with biomarkers (hs-cTnT, BNP, and eGFR) predicted clinical outcomes. hs-cTnT may be a useful biomarker for evaluating the therapeutic effect of tafamidis.
Topics: Humans; Prealbumin; Amyloidosis; Heart Failure; Biomarkers; Cardiomyopathies
PubMed: 37073415
DOI: 10.1002/ehf2.14380 -
Drugs Apr 2024Eplontersen (Wainua™) is a ligand-conjugated antisense oligonucleotide directed to TTR, which is being developed by Ionis Pharmaceuticals and AstraZeneca for the... (Review)
Review
Eplontersen (Wainua™) is a ligand-conjugated antisense oligonucleotide directed to TTR, which is being developed by Ionis Pharmaceuticals and AstraZeneca for the treatment of TTR-mediated amyloidosis (ATTR). Eplontersen, which is targeted to the liver by a ligand containing three N-acetyl galactosamine residues, binds to wild-type and variant TTR mRNA, thus reducing the levels of circulating TTR protein and amyloid deposition. Subcutaneous eplontersen reduced serum TTR levels, inhibited neuropathy progression and improved health-related quality of life in patients with polyneuropathy of hereditary ATTR (ATTRv-PN; v for variant) in a phase III trial. Based on these results, eplontersen was approved in the USA for the treatment of ATTRv-PN on 21 December 2023 and is currently undergoing regulatory review for a similar indication in the EU, the UK, Switzerland and Canada. Eplontersen is also undergoing phase III development for ATTR cardiomyopathy. This article summarizes the milestones in the development of eplontersen leading to this first approval for ATTRv-PN.
Topics: Humans; Amyloid Neuropathies, Familial; Prealbumin; Drug Approval; Oligonucleotides; Oligonucleotides, Antisense; Quality of Life; Clinical Trials, Phase III as Topic
PubMed: 38413492
DOI: 10.1007/s40265-024-02008-5