Patisiran Treatment in Patients with Transthyretin Cardiac Amyloidosis

Radionuclide Imaging of Cardiac Amyloidosis: An Update and Future Aspects

Cardiac amyloidosis (CA) is caused by the misfolding, accumulation and aggregation of proteins into large fibrils in the extracellular compartment of the myocardium, leading to restrictive cardiomyopathy, heart failure and death. The major forms are transthyretin (ATTR) CA and light-chain (AL) CA, based on the respective precursor protein. Each of them requires early diagnosis for a timely treatment initiation that will improve patient outcomes. For this, radionuclide imaging is essentially used as single-photon emission computed tomography (SPECT) with bone-avid radiotracers or as positron emission tomography (PET) with amyloid-binding radiotracers. Both offer unprecedented specificity for the diagnostic of CA. SPECT has even revolutionized the diagnosis of ATTR-CA by making it non-invasive. Indeed, SPECT has now entered the standard diagnostic pathway to CA and has led to earlier diagnosis of the disease. SPECT also modified the epidemiology of ATTR-CA, highlighting that the disease is much more frequent than previously believed, and showing that ATTR-CA plays a substantial role in HFpEF and aortic stenosis, particularly among elderly patients. In parallel, amyloid-binding radiotracers for PET have accumulated a substantial amount of evidence, but are not approved for clinical use in CA yet. Further studies are needed to refine acquisition protocols and validate results in broader populations. Unlike bone-avid SPECT radiotracers, PET radiotracers have been specifically created to bind to amyloid fibrils. Thus, PET is the only imaging method that is truly specific for amyloid deposits and very sensitive to any amyloid type. Indeed, PET can not only detect ATTR-CA, but also AL-CA and rare hereditary forms. For both SPECT and PET, advances in quantitation of myocardial uptake have generated more granular and reproducible findings, paving the way for progress in earlier diagnosis, risk stratification and therapeutic response monitoring. Encouraging findings have shown that SPECT and PET are sensitive to early CA when other diagnostic methods are negative. Both radionuclide imaging techniques can predict adverse outcomes, but more evidence is needed to determine how to use them in conjunction with usual prognostic staging scores. Studies on follow-up imaging after therapy suggested that SPECT and PET can capture myocardial changes in CA, but again, more data are needed to meaningfully interpret such changes. Based on all these promising results, radionuclide imaging has the potential to further impact the landscape of CA in diagnosis, prognosis and follow-up, but also to substantially contribute to the assessment of novel therapies that will improve the lives of patients with CA.

Treatment of transthyretin cardiac amyloidosis

PURPOSE OF REVIEW

Tafamidis is currently the only approved disease-modifying treatment for ATTR-CM. However, there have been important developments in the treatment of ATTR-CM, as the results of two phase 3 trials were published and several other trials are in their final stages. In this review, we summarize current and future therapies for ATTR-CM.

RECENT FINDINGS

Recently, acoramidis, a TTR stabilizer has been proven to be effective in reducing mortality and morbidity compared to placebo in the ATTRibute-CM trial. Additionally, patisiran, an RNA silencer, preserved functional capacity and quality of life compared to placebo in the APOLLO-B trial. However, the FDA declined to approve patisiran for ATTR-CM. The results of phase 1 trial of ALXN2220, an antiamyloid antibody raise hope for reversal of myocardial damage by amyloid depletion. Phase 3 trials evaluating the efficacy of different RNA silencers, gene editing with CRISPR-Cas9, and other anti-amyloid antibodies are ongoing.

SUMMARY

Therapies targeting different mechanism in the pathophysiology of ATTR-CM provide new alternatives for treating patients with ATTR-CM. Future research should focus on comparing their effectiveness, the potential of combined treatment with agents from different classes and on identifying the patients who will benefit most from each class of medication.

Successes in translation

Translational research is key in advancing the diagnosis and therapy of systemic amyloidoses. This paper summarises our presentations at the ISA Workshop on Translation in Systemic Amyloidoses held in Athens on September 25-26, 2023. The critical advances made by the pioneers in the field are reviewed, with particular attention to the discoveries and developments of utmost importance to our understanding of what amyloid is and how the substance affects functions. Examples of translational research regarding the mechanisms of cardiac damage in light chain amyloidosis, the role of biomarkers in improving our understanding of the biology of the disease and patients' management, and the molecular mechanisms involved in the cytotoxicity are described. Advances in basic research continue to open new therapeutic avenues.

Value of troponin and NT-proBNP to screen for cardiac amyloidosis after carpal tunnel syndrome surgery

BACKGROUND

Early diagnosis of cardiac amyloidosis (CA) is crucial due to the promising effect of disease-modifying treatment. This calls for screening strategies to identify CA patients with so-called "red flags", such as carpal tunnel syndrome (CTS).

OBJECTIVES

This study aims to assess Troponin-T (TnT) and N-terminal pro-B-type natriuretic peptide (NT-ProBNP) as predictors for CA in patients with a history of surgery for bilateral carpal tunnel syndrome, a population suitable for systematic screening.

METHODS

Subjects with a history of surgery for bilateral CTS 5-15 years prior, identified using national registries were investigated for CA as per international recommendations. Sensitivity, specificity, positive and negative predictive values were assessed, and receiver operating curves were generated using logistic regression.

RESULTS

Among the 250 participants, 12 were diagnosed with CA, all with wild-type transthyretin amyloidosis. Elevated TnT levels (≥13 ng/L) were found in all CA patients and 25.6% (±2.8) of non-CA patients. The negative predictive value (NPV) of TnT <13 ng/L was 100%. For NT-ProBNP the NPV was 99.1% when age dependent cutoff levels were used. A combination of both biomarkers yielded an NPV of 99.1% and sensitivity of 99.7%. Early disease (Mayo or NAC stage 1) was found in 83% of identified patients with CA.

CONCLUSION

This study demonstrates the utility of TnT and NT-ProBNP as negative predictors to exclude CA in a screening population with a history of surgery for CTS.

Mechanisms of damage and therapies for cardiac amyloidosis: a role for inflammation?

The term cardiac amyloidosis (CA) refers to the accumulation of extracellular amyloid deposits in the heart because of different conditions often affecting multiple organs including brain, kidney and liver. Notably, cardiac involvement significantly impacts prognosis of amyloidosis, with cardiac biomarkers playing a pivotal role in prognostic stratification. Therapeutic management poses a challenge due to limited response to conventional heart failure therapies, necessitating targeted approaches aimed at preventing, halting or reversing amyloid deposition. Mechanisms underlying organ damage in CA are multifactorial, involving proteotoxicity, oxidative stress, and mechanical interference. While the role of inflammation in CA remains incompletely understood, emerging evidence suggests its potential contribution to disease progression as well as its utility as a therapeutic target. This review reports on the cardiac involvement in systemic amyloidosis, its prognostic role and how to assess it. Current and emerging therapies will be critically discussed underscoring the need for further efforts aiming at elucidating CA pathophysiology. The emerging evidence suggesting the contribution of inflammation to disease progression and its prognostic role will also be reviewed possibly offering insights into novel therapeutic avenues for CA.

RNA interference therapy in cardiology: will new targets improve therapeutic goals?

The discovery of RNA interference in 1998 opened avenues for the manipulation of gene expression, leading to the development of small interfering RNA (siRNA) drugs. Patisiran, the first FDA-approved siRNA medication, targets hereditary transthyretin amyloidosis with polyneuropathy. Givosiran, lumasiran and nedosiran further expand siRNA applications in treating rare genetic diseases, demonstrating positive outcomes. In cardiology, inclisiran, approved for hypercholesterolaemia, showcases sustained reductions in LDL cholesterol levels. However, ongoing research aims to establish its impact on cardiovascular outcomes. Lipoprotein(a), an independent risk factor for atherosclerotic cardiovascular disease, has become a focus of siRNA therapies, precipitating the development of specific siRNA drugs like olpasiran, zerlasiran and lepodisiran, with promising reductions in lipoprotein(a) levels. Research to assess the effectiveness of these medications in reducing events is currently under way. Zodasiran and plozasiran address potential risk factors for cardiovascular diseases, targeting triglyceride-rich lipoproteins. Zilebesiran, which targets hepatic angiotensinogen mRNA, has demonstrated a dose-related reduction in serum angiotensinogen levels, thereby lowering blood pressure in patients with systemic arterial hypertension. The evolving siRNA methodology presents a promising future in cardiology, with ongoing studies assessing its effectiveness in various conditions. In the future, larger studies will provide insights into improvements in cardiovascular outcomes, long-term safety and broader applications in the general population. This review highlights the historical timeline of the development of siRNA-based drugs, their clinical indications, potential side-effects and future perspectives.

Sex Differences in Transthyretin Cardiac Amyloidosis: Unraveling the Complexities in Epidemiology, Pathophysiology, Diagnosis, and Treatment

Transthyretin cardiac amyloidosis (ATTR-CA) is characterised by the deposition of transthyretin amyloid fibrils in the heart. ATTR-CA affects both men and women although there is evidence of sex differences in prevalence and clinical presentation. PURPOSE OF REVIEW: This review paper aims to comprehensively examine and synthesise the existing literature on sex differences in ATTR-CA. RECENT FINDINGS: The prevalence of ATTR-CA is higher in males although the male predominance is more apparent in older patients in the wild type form and in TTR genetic variants that predominantly result in a cardiac phenotype in the hereditary variant. Women tend to have less left ventricular hypertrophy (LVH) and a higher ejection fraction at clinical presentation which may contribute to a later diagnosis although the prognosis appears to be similar in both sexes. Female sex is a predictor of a good response to tafamidis 20 mg in TTR polyneuropathy but otherwise there are no data on sex differences in the efficacy of other treatments for ATTR-CA. It is crucial to define specific sex differences in ATTR-CA. A lower cut-off value for LVH in women may be needed to improve diagnosis. It is necessary to increase female representation in clinical trials to better understand possible sex differences in therapeutic management.

Lymphatic endothelial cell-targeting lipid nanoparticles delivering VEGFC mRNA improve lymphatic function after injury

Dysfunction of the lymphatic system following injury, disease, or cancer treatment can lead to lymphedema, a debilitating condition with no cure. Advances in targeted therapy have shown promise for treating diseases where conventional therapies have been ineffective and lymphatic vessels have recently emerged as a new therapeutic target. Lipid nanoparticles (LNPs) have emerged as a promising strategy for tissue specific delivery of nucleic acids. Currently, there are no approaches to target LNPs to lymphatic endothelial cells, although it is well established that intradermal (ID) injection of nanoparticles will drain to lymphatics with remarkable efficiency. To design an LNP that would effectively deliver mRNA to LEC after ID delivery, we screened a library of 150 LNPs loaded with a reporter mRNA, for both self-assembly and delivery in vivo to lymphatic endothelial cells (LECs). We identified and validated several LNP formulations optimized for high LEC uptake when administered ID and compared their efficacy for delivery of functional mRNA with that of free mRNA and mRNA delivered with a commercially available MC3-based LNP (Onpattro™). The lead LEC-specific LNP was then loaded with VEGFC mRNA to test the therapeutic advantage of the LEC-specific LNP (namely, LNP7) for treating a mouse tail lymphatic injury model. A single dose of VEGFC mRNA delivered via LNP7 resulted in enhanced LEC proliferation at the site of injury, and an increase in lymphatic function up to 14-days post-surgery. Our results suggest a therapeutic potential of VEGFC mRNA lymphatic-specific targeted delivery in alleviating lymphatic dysfunction observed during lymphatic injury and could provide a promising approach for targeted, transient lymphangiogenic therapy.

Recent advances in the diagnostic methods and therapeutic strategies of transthyretin cardiac amyloidosis

Cardiac amyloidosis is a progressive disease characterized by the buildup of amyloid fibrils in the extracellular space of the heart. It is divided in 2 main types, immunoglobulin light chain amyloidosis and transthyretin amyloidosis (ATTR), and ATTR amyloidosis is further divided in 2 subtypes, non-hereditary wild type ATTR and hereditary mutant variant amyloidosis. Incidence and prevalence of ATTR cardiac amyloidosis is increasing over the last years due to the improvements in diagnostic methods. Survival rates are improving due to the development of novel therapeutic strategies. Tafamidis is the only disease-modifying approved therapy in ATTR amyloidosis so far. However, the most recent advances in medical therapies have added more options with the potential to become part of the therapeutic armamentarium of the disease. Agents including acoramidis, eplontersen, vutrisiran, patisiran and anti-monoclonal antibody NI006 are being investigated on cardiac function in large, multicenter controlled trials which are expected to be completed within the next 2-3 years, providing promising results in patients with ATTR cardiac amyloidosis. However, further and ongoing research is required in order to improve diagnostic methods that could provide an early diagnosis, as well as survival and quality of life of these patients.

Stimulus-Responsive Nanodelivery and Release Systems for Cancer Gene Therapy: Efficacy Improvement Strategies

Introduction of exogenous genes into target cells to overcome various tumor diseases caused by genetic defects or abnormalities and gene therapy, a new treatment method, provides a promising strategy for tumor treatment. Over the past decade, gene therapy has made exciting progress; however, it still faces the challenge of low nucleic acid delivery and release efficiencies. The emergence of nonviral vectors, primarily nanodelivery and release systems (NDRS), has resulted in a historic breakthrough in the application of gene therapy. NDRS, especially stimulus-responsive NDRS that can respond in a timely manner to changes in the internal and external microenvironment (eg, low pH, high concentration of glutathione/reactive oxygen species, overexpressed enzymes, temperature, light, ultrasound, and magnetic field), has shown excellent loading and release advantages in the precision and efficiency of tumor gene therapy and has been widely applied. The only disadvantage is that poor transfection efficiency limits the in-depth application of gene therapy in clinical practice, owing to the presence of biological barriers in the body. Therefore, this review first introduces the development history of gene therapy, the current obstacles faced by gene delivery, strategies to overcome these obstacles, and conventional vectors, and then focuses on the latest research progress in various stimulus-responsive NDRS for improving gene delivery efficiency. Finally, the future challenges and prospects that stimulus-responsive NDRS may face in clinical application and transformation are discussed to provide references for enhancing in-depth research on tumor gene therapy.

Tafamidis therapy in transthyretin amyloid cardiomyopathy: a narrative review from clinical trials and real-world evidence

BACKGROUND

Amyloidosis is a heterogeneous group of disorders caused by the extracellular deposition of insoluble misfolded proteins, leading to end-organ damage. Transthyretin amyloid cardiomyopathy (ATTR-CM) is a subtype in which a protein known as transthyretin accumulates within the heart tissue, progressively resulting in restrictive cardiomyopathy and heart failure. Due to the progressive nature of ATTR-CM, clinical management requires efficacious regimens to manage the debilitating condition and Tafamidis shows promising results in this regard.

MAIN BODY

ATTR-CM poses a significant challenge due to its nature and limited therapeutic options. Tafamidis is a novel therapy designed to stabilize the transthyretin tetramers, inhibiting the formation of amyloid fibrils. It has emerged as a promising treatment and the only FDA-approved drug for ATTR-CM. Tafamidis' role in slowing disease progression and improving outcomes in patients with ATTR-CM has been demonstrated in the major randomized control trial ATTR-ACT with promising open-label extension studies, some still ongoing. Additionally, real-world evidence supports its use in clinical practice, showing its role in reducing morbidity and mortality associated with this condition. Clinical evidence shows its efficacy in improving symptoms and cardiac function in patients. Case studies also reveal significant benefits to patients like reducing myocardial damage, reversal of atrial fibrillation, and resolution of heart failure symptoms. Real-world outcomes and clinical trials show a consistent reduction in amyloid deposition, cardiovascular-related hospitalizations, and all-cause mortality with Tafamidis therapy.

CONCLUSION

Tafamidis is an essential component of the treatment of ATTR-CM and this narrative review synthesizes the current evidence regarding safety, efficacy, and utilization in real practice. While it shows promising effects, its effectiveness may also vary and high cost precludes real-world large-scale studies. Overall, Tafamidis emerges as a valuable therapeutic option for managing ATTR-CM.

Prognostic Value of a 6-Minute Walk Test in Patients With Transthyretin Cardiac Amyloidosis

BACKGROUND

The 6-minute walk test (6MWT) represents a comprehensive functional assessment that is commonly used in patients with heart failure; however, data are lacking in patients with transthyretin cardiac amyloidosis (ATTR-CA).

OBJECTIVES

This study aimed to assess the prognostic importance of the 6MWT in patients with ATTR-CA.

METHODS

A retrospective analysis of patients diagnosed with ATTR-CA at the National Amyloidosis Centre who underwent a baseline 6MWT between 2011 and 2023 identified 2,141 patients, of whom 1,118 had follow-up at 1 year.

RESULTS

The median baseline 6MWT distance was 347 m (Q1-Q3: 250-428 m) and analysis by quartiles demonstrated an increased death rate with each distance reduction (deaths per 100 person-years: 6.3 vs 9.2 vs 13.6 vs 19.0; log-rank P < 0.001). A 6MWT distance of <350 m was associated with a 2.2-fold higher risk of mortality (HR: 2.15; 95% CI: 1.85-2.50; P < 0.001), with a similar increased risk across National Amyloidosis Centre disease stages (P for interaction = 0.761) and genotypes (P for interaction = 0.172). An absolute (reduction of >35 m) and relative worsening (reduction of >5%) of 6MWT at 1 year was associated with an increased risk of mortality (HR: 1.80; 95% CI: 1.51-2.15; P < 0.001 and HR: 1.89; 95% CI: 1.59-2.24; P < 0.001, respectively), which was similar across the aforementioned subgroups. When combined with established measures of disease progression (N-terminal pro-B-type natriuretic peptide progression and outpatient diuretic intensification), each incremental increase in progression markers was associated with an increased death rate (deaths per 100 person-years: 7.6 vs 13.9 vs 22.4 vs 32.9; log-rank P < 0.001).

CONCLUSIONS

The baseline 6MWT distance can refine risk stratification beyond traditional prognosticators. A worsening 6MWT distance can stratify disease progression and, when combined with established markers, identifies patients at the highest risk of mortality.

Advancing Transthyretin Amyloidosis Drug Development in an Evolving Treatment Landscape: Amyloidosis Forum Meeting Proceedings

INTRODUCTION

Hereditary transthyretin amyloidosis (ATTRv, also referred to as hATTR; ORPHA 271861) and wild-type ATTR amyloidosis (ATTRwt; ORPHA 330001) are rare, progressive, systemic protein misfolding disorders with heterogeneous clinical presentations. ATTRv and ATTRwt amyloidosis are characterized by the deposition of amyloid fibrils in multiple organs including the heart, nerves, eyes, and soft tissues. The management of ATTR amyloidosis is complex because of its multisystemic nature and progression despite available treatment options. Morbidity is high and there are many unmet medical needs for patients. While contemporary ATTR amyloidosis cohorts are diagnosed earlier, have lower risk disease and lower mortality compared with the previous era, these advances coupled with the emergence of effective disease-modifying therapies have confounded the design of future prospective clinical trials and interpretation of historical control data.

MAIN BODY

The Amyloidosis Forum is a public-private partnership between the US Food and Drug Administration Center for Drug Evaluation and Research and the nonprofit Amyloidosis Research Consortium ( www.arci.org ). This article summarizes proceedings from the 21 June 2023 Amyloidosis Forum on advancing drug development in ATTR amyloidosis in an evolving treatment landscape. The Forum focused on elements of clinical trial design to address these challenges and discussed their strengths and weaknesses from multiple stakeholder perspectives (i.e., patient, sponsor, statistician, clinician, and regulatory authorities).

CONCLUSION

Given rapid evolution of natural history in ATTR amyloidosis, the utility of historical control data is limited. Leveraging contemporary real-world data is essential for clinical trial design. Evidence generation from clinical trials should address clinically relevant questions. Key factors in successful trial design must be informed by up-to-date data on natural history, prognostic factors, clinically meaningful thresholds, and sharing available clinical trial data. The Amyloidosis Forum includes the community of patients with ATTR amyloidosis, the physicians who treat them, and the sponsors and regulators who collectively stand ready to support further studies in order to develop novel effective therapies.

Recent updates on therapeutic targeting of lipoprotein(a) with RNA interference

PURPOSE OF REVIEW

RNA interference (RNAi)-based therapies that target specific gene products have impacted clinical medicine with 16 FDA approved drugs. RNAi therapy focused on reducing plasma lipoprotein(a) [Lp(a)] levels are under evaluation.

RECENT FINDINGS

RNAi-based therapies have made significant progress over the past 2 decades and currently consist of antisense oligonucleotides (ASO) and small interfering RNA (siRNA). Chemical modification of the RNA backbone and conjugation of siRNA enables efficient gene silencing in hepatocytes allowing development of effective cholesterol lowering therapies. Multiple lines of evidence suggest a causative role for Lp(a) in atherosclerotic cardiovascular disease, and recent analyses indicate that Lp(a) is more atherogenic than low density lipoprotein- cholesterol (LDL-C). These findings have led to the 'Lp(a) hypothesis' that lowering Lp(a) may significantly improve cardiovascular outcomes. Four RNAi-based drugs have completed early phase clinical trials demonstrating >80% reduction in plasma Lp(a) levels. Phase 3 clinical trials examining clinical outcomes with these agents are currently underway.

SUMMARY

Currently, four RNAi-based drugs have been shown to be effective in significantly lowering plasma Lp(a) levels. Clinical outcome data from phase 3 trials will evaluate the Lp(a) hypothesis.

Deep Learning-Enabled Quantification of 99mTc-Pyrophosphate SPECT/CT for Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR CA) is increasingly recognized as a cause of heart failure in older patients, with 99mTc-pyrophosphate imaging frequently used to establish the diagnosis. Visual interpretation of SPECT images is the gold standard for interpretation but is inherently subjective. Manual quantitation of SPECT myocardial 99mTc-pyrophosphate activity is time-consuming and not performed clinically. We evaluated a deep learning approach for fully automated volumetric quantitation of 99mTc-pyrophosphate using segmentation of coregistered anatomic structures from CT attenuation maps. Methods: Patients who underwent SPECT/CT 99mTc-pyrophosphate imaging for suspected ATTR CA were included. Diagnosis of ATTR CA was determined using standard criteria. Cardiac chambers and myocardium were segmented from CT attenuation maps using a foundational deep learning model and then applied to attenuation-corrected SPECT images to quantify radiotracer activity. We evaluated the diagnostic accuracy of target-to-background ratio (TBR), cardiac pyrophosphate activity (CPA), and volume of involvement (VOI) using the area under the receiver operating characteristic curve (AUC). We then evaluated associations with the composite outcome of cardiovascular death or heart failure hospitalization. Results: In total, 299 patients were included (median age, 76 y), with ATTR CA diagnosed in 83 (27.8%) patients. CPA (AUC, 0.989; 95% CI, 0.974-1.00) and VOI (AUC, 0.988; 95% CI, 0.973-1.00) had the highest prediction performance for ATTR CA. The next highest AUC was for TBR (AUC, 0.979; 95% CI, 0.964-0.995). The AUC for CPA was significantly higher than that for heart-to-contralateral ratio (AUC, 0.975; 95% CI, 0.952-0.998; P = 0.046). Twenty-three patients with ATTR CA experienced cardiovascular death or heart failure hospitalization. All methods for establishing TBR, CPA, and VOI were associated with an increased risk of events after adjustment for age, with hazard ratios ranging from 1.41 to 1.84 per SD increase. Conclusion: Deep learning segmentation of coregistered CT attenuation maps is not affected by the pattern of radiotracer uptake and allows for fully automatic quantification of hot-spot SPECT imaging such as 99mTc-pyrophosphate. This approach can be used to accurately identify patients with ATTR CA and may play a role in risk prediction.

Evolution of Disease-modifying Therapy for Transthyretin Cardiac Amyloidosis

Transthyretin cardiac amyloidosis (ATTR-CA) represents an inexorably progressive and fatal cardiomyopathy. Increased understanding of the underlying pathogenesis responsible for the misfolding of transthyretin and the subsequent accumulation of amyloid fibrils within the myocardium has led to the development of several disease-modifying therapies that act on different stages of the disease pathway. Tafamidis is the first, and to date remains the only, therapy approved for the treatment of ATTR-CA, which, alongside acoramidis, stabilizes the transthyretin tetramer, preventing disaggregation, misfolding and formation of amyloid fibrils. Gene-silencing agents, such as patisiran, vutrisian and eplontersen, and novel gene-editing therapies, such as NTLA-2001, act to reduce the hepatic synthesis of transthyretin. Anti-amyloid therapies represent another strategy in the treatment of ATTR-CA and are designed to bind amyloid fibril epitopes and stimulate macrophage-mediated removal of amyloid fibrils from the myocardium. Many of these treatments are at an early investigational stage but represent an important area of unmet clinical need and could potentially reverse disease and restore cardiac functions even in patients with advanced disease.

Expansion of the National Amyloidosis Centre staging system to detect early mortality in transthyretin cardiac amyloidosis

AIMS

Transthyretin cardiac amyloidosis (ATTR-CA) is stratified into prognostic categories using the National Amyloidosis Centre (NAC) staging system. The aims of this study were to further expand the existing NAC staging system to incorporate an additional disease stage that would identify patients at high risk of early mortality.

METHODS AND RESULTS

The traditional NAC staging system (stage 1: N-terminal pro-B-type natriuretic peptide [NT-proBNP] ≤3000 ng/L and estimated glomerular filtration rate [eGFR] ≥45 ml/min; stage 3: NT-proBNP >3000 ng/L and eGFR <45 ml/min; stage 2: remainder) was expanded by the introduction of a new stage 4 (defined as NT-proBNP ≥10 000 ng/L irrespective of eGFR) and studied in 2042 patients. The optimal NT-proBNP cut-point was established using time-dependent receiver operating characteristic curves in the subgroup of patients with NAC stage 3 disease. Mortality at 1 year according to NAC stage was 2.3% (n = 20/886) for stage 1, 8.8% (n = 62/706) for stage 2, 10.4% (n = 28/270) for stage 3, and 30.6% (n = 55/180) for stage 4 (log-rank p < 0.001). After adjustment for age, mortality hazard for stage 4 was >15-fold higher than that of stage 1 (hazard ratio [HR] 15.5; 95% confidence interval [CI] 9.3-26.1) and >3-fold higher than that of stage 3 (HR 3.4; 95% CI 2.2-5.4). The increased risk of early mortality was consistent across the different genotypes and subclasses of patients based on the severity of heart failure symptoms and echocardiographic parameters.

CONCLUSIONS

The proposed modification of the NAC staging system identifies patients with ATTR-CA at a high risk of early mortality, who may benefit from a more intensive treatment strategy, and who are most likely to experience an event early in the course of a clinical trial.

Evaluation of the 2021 ESC recommendations for family screening in hereditary transthyretin cardiac amyloidosis

AIMS

The 2021 European Society of Cardiology (ESC) screening recommendations for individuals carrying a pathogenic transthyretin amyloidosis variant (ATTRv) are based on expert opinion. We aimed to (i) determine the penetrance of ATTRv cardiomyopathy (ATTRv-CM) at baseline; (ii) examine the value of serial evaluation; and (iii) establish the yield of first-line diagnostic tests (i.e. electrocardiogram, echocardiogram, and laboratory tests) as per 2021 ESC position statement.

METHODS AND RESULTS

We included 159 relatives (median age 55.6 [43.2-65.9] years, 52% male) at risk for ATTRv-CM from 10 centres. The primary endpoint, ATTRv-CM diagnosis, was defined as the presence of (i) cardiac tracer uptake in bone scintigraphy; or (ii) transthyretin-positive cardiac biopsy. The secondary endpoint was a composite of heart failure (New York Heart Association class ≥II) and pacemaker-requiring conduction disorders. At baseline, 40/159 (25%) relatives were diagnosed with ATTRv-CM. Of those, 20 (50%) met the secondary endpoint. Indication to screen (≤10 years prior to predicted disease onset and absence of extracardiac amyloidosis) had an excellent negative predictive value (97%). Other pre-screening predictors for ATTRv-CM were infrequently identified variants and male sex. Importantly, 13% of relatives with ATTRv-CM did not show any signs of cardiac involvement on first-line diagnostic tests. The yield of serial evaluation (n = 41 relatives; follow-up 3.1 [2.2-5.2] years) at 3-year interval was 9.4%.

CONCLUSIONS

Screening according to the 2021 ESC position statement performs well in daily clinical practice. Clinicians should adhere to repeating bone scintigraphy after 3 years, as progressing to ATTRv-CM without signs of ATTRv-CM on first-line diagnostic tests or symptoms is common.

Patisiran for the treatment of patients with p.Ile88Leu hereditary transthyretin amyloidosis: an Italian real-life experience

Objectives

Evidence on the activity of patisiran therapy in specific subgroups of patients with hereditary transthyretin amyloidosis variant (ATTRv) is still scarce. This prospective real-world study was designed to provide the first in-depth clinical data on the effectiveness of patisiran in patients with ATTRv reporting the p.Ile88Leu variant, the most widespread variant in the Emilia-Romagna regional area, which has been less represented in previous clinical trials.

Patients and methods

This prospective study evaluated all the patients with genetically proven ATTRv (p.Ile88Leu) and polyneuropathy treated with patisiran in the Emilia-Romagna referral centers for ATTRv (Institute of Neurological Sciences in Bologna and Division of Neurology in Rimini) from March 2021 to April 2023. All subjects underwent clinical and neurological evaluations at baseline and after 9-12 months of treatment.

Results

A total of 22 patients were included in the study; the median age was 73 years (IQR: 9), the age at diagnosis was 72 years (IQR: 10), and the disease duration was 1.6 years (IQR: 2.3). We observed stability of all considered neurological and cardiological parameters at 9-12 months after the beginning of patisiran treatment.

Conclusion

Our findings support the clinical data regarding the effectiveness of patisiran in stabilizing the disease course and extend this activity to the subset of patients with the p.Ile88Leu variant.

Cardiovascular Burden of the V142I Transthyretin Variant

Importance

Individual cohort studies concur that the amyloidogenic V142I variant of the transthyretin (TTR) gene, present in 3% to 4% of US Black individuals, increases heart failure (HF) and mortality risk. Precisely defining carrier risk across relevant clinical outcomes and estimating population burden of disease are important given established and emerging targeted treatments.

Objectives

To better define the natural history of disease in carriers across mid to late life, assess variant modifiers, and estimate cardiovascular burden to the US population.

Design, Setting, and Participants

A total of 23 338 self-reported Black participants initially free from HF were included in 4 large observational studies across the US (mean [SD], 15.5 [8.2] years of follow-up). Data analysis was performed between May 2023 and February 2024.

Exposure

V142I carrier status (n = 754, 3.2%).

Main Outcomes and Measures

Hospitalizations for HF (including subtypes of reduced and preserved ejection fraction) and all-cause mortality. Outcomes were analyzed by generating 10-year hazard ratios for each age between 50 and 90 years. Using actuarial methods, mean survival by carrier status was estimated and applied to the 2022 US population using US Census data.

Results

Among the 23 338 participants, the mean (SD) age at baseline was 62 (9) years and 76.7% were women. Ten-year carrier risk increased for HF hospitalization by age 63 years, predominantly driven by HF with reduced ejection fraction, and 10-year all-cause mortality risk increased by age 72 years. Only age (but not sex or other select variables) modified risk with the variant, with estimated reductions in longevity ranging from 1.9 years (95% CI, 0.6-3.1) at age 50 to 2.8 years (95% CI, 2.0-3.6) at age 81. Based on these data, 435 851 estimated US Black carriers between ages 50 and 95 years are projected to cumulatively lose 957 505 years of life (95% CI, 534 475-1 380 535) due to the variant.

Conclusions and Relevance

Among self-reported Black individuals, male and female V142I carriers faced similar and substantial risk for HF hospitalization, predominantly with reduced ejection fraction, and death, with steep age-dependent penetrance. Delineating the individual contributions of, and complex interplay among, the V142I variant, ancestry, the social construct of race, and biological or social determinants of health to cardiovascular disease merits further investigation.

Race and Socioeconomic Status Impact Diagnosis and Clinical Outcomes in Transthyretin Cardiac Amyloidosis

Background

Transthyretin amyloid cardiomyopathy (ATTR-CM) is associated with significant mortality. The Val122Ile variant, highly prevalent in Black patients, portends poorer survival compared with other ATTR-CM subtypes. Although Val122Ile is biologically more aggressive, the contribution of race and socioeconomic status (SES) to disease outcomes in patients with ATTR-CM is undefined.

Objectives

The aim of this study was to evaluate the impact of race and SES on clinical outcomes in patients with ATTR-CM.

Methods

Patients with ATTR-CM who received care at Johns Hopkins Hospital between 2006 and 2022 were included. SES was assessed using area deprivation index (ADI). Associations of race and ADI with heart failure (HF) hospitalization and/or death were measured using multivariable logistic or Cox proportional hazards models.

Results

Of 282 patients, 225 (80%) were men, and 129 (46%) were Black. Black vs White patients disproportionately constituted the highest ADI (most deprived) category (66% vs 28%; P = 0.004), and Black patients were more likely to have HF hospitalization or death over 5 years compared with White patients (log-rank P < 0.001). Among those with ADI >25, Black patients had a significantly greater hazard of HF hospitalization or death compared with White patients, independent of disease stage at diagnosis (HR: 2.77; 95% CI: 1.45-5.32; P = 0.002).

Conclusions

Black patients with low SES may be at greater risk for underdiagnosis and adverse outcomes compared with White patients. Ongoing efforts are needed to improve outcomes in this subset of patients with ATTR-CM.

Gene-based therapies for neuromuscular disorders

Neuromuscular diseases (NMD) include a broad group of medical conditions with both acquired and genetic causes. In recent years, important advances have been made in the treatment of genetically caused NMD, and most of these advances are due to the implementation of therapies aimed at gene regulation. Among these therapies, gene replacement, small interfering RNA (siRNA), and antisense antinucleotides are the most promising approaches. More importantly, some of these therapies have already gained regulatory approval or are in the final stages of approval. The review focuses on motor neuron diseases, neuropathies, and Duchenne muscular dystrophy, summarizing the most recent developments in gene-based therapies for these conditions.

Cardiac amyloidosis red flags: What all the cardiologist have to know

Cardiac amyloidosis is becoming increasingly important among cardiologist and an early diagnosis is very important. Amyloidosis is a systemic disease and many cardiac and extracardiac elements (red flags) should raise the suspicion of the disease. Electrocardiographic and imaging techniques (such as echocardiography, cardiac magnetic resonance and scintigraphy) are useful tools to make a diagnosis together with the presence of orthopedic issues, peripheral neuropathy or plasma cell dyscrasia. Cardiac amyloidosis is also often associated with valvular disorder, heart failure or cardiomyopathy. Red flags are crucial to raise suspicion and reach an early diagnosis, in order to start a targeted treatment strategy that could change the patient's outcome. Indeed, in the last years four new drugs were approved to treat transthyretin amyloidosis.

A real-world pharmacovigilance analysis for transthyretin inhibitors: findings from the FDA adverse event reporting database

Objective

The purpose of this study is to investigate the drug safety of three Transthyretin (TTR) inhibitors in the real world using the United States Food and Drug Administration Adverse Event Reporting System (FAERS) database.

Methods

This study extracted reports received by the FAERS database from the first quarter of 2018 to the third quarter of 2023 for descriptive analysis and disproportionality analysis. Safety signal mining was conducted at the Preferred Term (PT) level and the System Organ Class (SOC) level using reporting odds ratio (ROR). The characteristics of the time-to-onset curves were analyzed using the Weibull Shape Parameter (WSP). The cumulative incidence of TTR inhibitors was evaluated using the Kaplan-Meier method. Subgroup analyses were conducted based on whether the reporter was a medical professional.

Results

A total of 3,459 reports of adverse events (AEs) caused by TTR inhibitors as the primary suspect (PS) drug were extracted. The top three reported AEs for patisiran were fatigue, asthenia, and fall, with the most unexpectedly strong association being nonspecific reaction. The top three reported AEs for vutrisiran were fall, pain in extremity and malaise, with the most unexpectedly strong association being subdural haematoma. The top three reported AEs for inotersen were platelet count decreased, blood creatinine increased, and fatigue, with the most unexpectedly strong association being blood albumin decreased. Vitamin A decreased, arthralgia, and dyspnea were the same AEs mentioned in the drug labels of all three drugs, while malaise and asthenia were the same unexpected significant signals. This study offers evidence of the variability in the onset time characteristics of AEs associated with TTR inhibitors, as well as evidence of differences in adverse event reporting between medical professionals and non-medical professionals.

Conclusion

In summary, we compared the similarities and differences in drug safety of three TTR inhibitors in the real world using the FAERS database. The results indicate that not only do these three drugs share common AEs, but they also exhibit differences in drug safety profiles. This study contributes to enhancing the understanding of medical professionals regarding the safety of TTR inhibitors.

2024 update in heart failure

In the last years, major progress has occurred in heart failure (HF) management. The 2023 ESC focused update of the 2021 HF guidelines introduced new key recommendations based on the results of the last years of science. First, two drugs, sodium-glucose co-transporter-2 (SGLT2) inhibitors and finerenone, a novel nonsteroidal, selective mineralocorticoid receptor antagonist (MRA), are recommended for the prevention of HF in patients with diabetic chronic kidney disease (CKD). Second, SGLT2 inhibitors are now recommended for the treatment of HF across the entire left ventricular ejection fraction spectrum. The benefits of quadruple therapy in patients with HF with reduced ejection fraction (HFrEF) are well established. Its rapid and early up-titration along with a close follow-up with frequent clinical and laboratory re-assessment after an episode of acute HF (the so-called 'high-intensity care' strategy) was associated with better outcomes in the STRONG-HF trial. Patients experiencing an episode of worsening HF might require a fifth drug, vericiguat. In the STEP-HFpEF-DM and STEP-HFpEF trials, semaglutide 2.4 mg once weekly administered for 1 year decreased body weight and significantly improved quality of life and the 6 min walk distance in obese patients with HF with preserved ejection fraction (HFpEF) with or without a history of diabetes. Further data on safety and efficacy, including also hard endpoints, are needed to support the addition of acetazolamide or hydrochlorothiazide to a standard diuretic regimen in patients hospitalized due to acute HF. In the meantime, PUSH-AHF supported the use of natriuresis-guided diuretic therapy. Further options and most recent evidence for the treatment of HF, including specific drugs for cardiomyopathies (i.e., mavacamten in hypertrophic cardiomyopathy and tafamidis in transthyretin cardiac amyloidosis), device therapies, cardiac contractility modulation and percutaneous treatment of valvulopathies, with the recent finding from the TRILUMINATE Pivotal trial, are also reviewed in this article.

Changes in the diagnostic trajectory of transthyretin cardiac amyloidosis over six years

Awareness of transthyretin amyloid cardiomyopathy (ATTR-CM) has increased over the years due to diagnostic and therapeutic developments. Timely initiation of novel disease-modifying treatments improves both morbidity and mortality, which underlines the necessity for a prompt diagnosis. Nevertheless, early diagnosis of ATTR-CM remains challenging. This is a retrospective observational cohort study of patients diagnosed with ATTR-CM. Between 2016 and 2023, 87 patients were diagnosed with cardiac amyloidosis of which 65 (75%) patients with ATTR-CM and 22 (25%) patients with light chain amyloidosis. This study included 65 ATTR-CM patients (mean age 77 ± 7 years; 86% male) of whom 59 (91%) with wild-type ATTR-CM (ATTRwt) and six (9%) with variant ATTR-CM. We observed a surge in ATTR-CM diagnoses from 3 patients/year (2016-2020) to 16 patients/year (2021-2023), driven by ATTRwt. Nevertheless, the interval between the onset of heart failure symptoms and ATTR-CM diagnosis has not changed significantly (2016-2020 27.3 months [18.6-62.4]; 2021-2023 30.0 months [8.6-57.2]; p = 0.546), driven by time to referral. Red flags for ATTR-CM preceded diagnosis by several years: left ventricular hypertrophy (79%, 5.8 years [3.3-7.0]) and carpal tunnel syndrome (49%, 6.8 years [2.3-12.1]). Despite the presence of typical red flags, symptom-to-diagnosis duration has remained similar driven by time to referral. Improved recognition of red flags for ATTR-CM could reduce the time to diagnosis and improve overall recognition.

Loss of monomeric alpha-synuclein (synucleinopenia) and the origin of Parkinson's disease

These facts argue against the gain-of-function synucleinopathy hypothesis, which proposes that Lewy pathology causes Parkinson's disease: (1) most brains from people without neurological symptoms have multiple pathologies; (2) neither pathology type nor distribution correlate with disease severity or progression in Parkinson's disease; (3) aggregated α-synuclein in the form of Lewy bodies is not a space-occupying lesion but the insoluble fraction of its precursor, soluble monomeric α-synuclein; (4) pathology spread is passive, occurring by irreversible nucleation, not active replication; and (5) low cerebrospinal fluid α-synuclein levels predict brain atrophy and clinical disease progression. The transformation of α-synuclein into Lewy pathology may occur as a response to biological, toxic, or infectious stressors whose persistence perpetuates the nucleation process, depleting normal α-synuclein and eventually leading to Parkinson's symptoms from neuronal death. We propose testing the loss-of-function synucleinopenia hypothesis by evaluating the clinical and neurodegenerative rescue effect of replenishing the levels of monomeric α-synuclein.

Regional Distribution of Extracellular Volume Quantified by Cardiac CT in Aortic Stenosis: Insights Into Disease Mechanisms and Impact on Outcomes

BACKGROUND

Extracellular volume fraction (ECV) is a marker for myocardial fibrosis and infiltration, can be quantified using cardiac computed tomography (ECVCT), and has prognostic utility in several diseases. This study aims to map out regional differences in ECVCT to obtain greater insights into the pathophysiological mechanisms of ECV expansion and its clinical implications.

METHODS

Three prospective cohorts were included: patients with aortic stenosis (AS) and coexisting AS and transthyretin cardiac amyloidosis were referred for a transcatheter aortic valve replacement and had ECG-gated CT angiography and Technetium-99m-labelled 3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy to differentiate between the 2 cohorts. Controls had CT angiography and cardiac magnetic resonance demonstrating no significant coronary artery disease or infarction. Global and regional ECVCT was analyzed, and its association with mortality was assessed for patients with AS.

RESULTS

In 199 patients, controls (n=65; 66% male), AS (n=115), and coexisting AS and transthyretin cardiac amyloidosis (n=19) had a global ECVCT of 26.1 (25.0-27.8%) versus 29.1 (27.5-31.1%) versus 37.4 (32.5-46.6%), respectively; P<0.001. Across cohorts, ECVCT was higher at the base (versus apex), the inferoseptum (versus anterolateral wall), and the subendocardium (versus subepicardium); P<0.05 for all. Among patients with AS, epicardial ECVCT, rather than any other regional value or global ECVCT, was the strongest predictor of mortality at a median of 3.9 (max 6.3) years (adjusted hazard ratio, 1.21 [95% CI, 1.08-1.36]; P=0.002).

CONCLUSIONS

Regional differences in ECVCT suggest a predilection for fibrosis and amyloid infiltration at the base, subendocardium, inferior wall, and septum more than the anterior and lateral myocardium. ECVCT can predict long-term mortality with the subepicardium demonstrating the strongest discriminatory power.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03029026 and NCT03094143.

Aging in Heart Failure: Embracing Biology Over Chronology: JACC Family Series

Age is among the most potent risk factors for developing heart failure and is strongly associated with adverse outcomes. As the global population continues to age and the prevalence of heart failure rises, understanding the role of aging in the development and progression of this chronic disease is essential. Although chronologic age is on a fixed course, biological aging is more variable and potentially modifiable in patients with heart failure. This review describes the current knowledge on mechanisms of biological aging that contribute to the pathogenesis of heart failure. The discussion focuses on 3 hallmarks of aging-impaired proteostasis, mitochondrial dysfunction, and deregulated nutrient sensing-that are currently being targeted in therapeutic development for older adults with heart failure. In assessing existing and emerging therapeutic strategies, the review also enumerates the importance of incorporating geriatric conditions into the management of older adults with heart failure and in ongoing clinical trials.

Vutrisiran: a new drug in the treatment landscape of hereditary transthyretin amyloid polyneuropathy

INTRODUCTION

Hereditary transthyretin (ATTRv) amyloidosis is a progressive, fatal disorder caused by mutations in the transthyretin (TTR) gene leading to deposition of the misfolded protein in amyloid fibrils. The main phenotypes are peripheral neuropathy (PN) and cardiomyopathy (CM).

AREAS COVERED

Gene silencing therapy, by dramatically reducing liver production of TTR, has transformed ATTRv-PN patient care in the last decade. In this drug discovery case history, the authors discuss the treatment history of ATTRv-PN and focus on the latest siRNA therapy: vutrisiran. Vutrisiran is chemically enhanced and N-acetylgalactosamin-conjugated, allowing increased stability and specific liver delivery. HELIOS-A, a phase III, multicenter randomized study, tested vutrisiran in ATTRv-PN and showed significant improvement in neuropathy impairment, disability, quality of life (QoL), gait speed, and nutritional status. Tolerance was acceptable, no safety signals were raised.

EXPERT OPINION

Vutrisiran offers a new treatment option for patients with ATTRv-PN. Vutrisian's easier delivery and administration route, at a quarterly frequency, as well as the absence of premedication, are major improvements to reduce patients' disease burden and improve their QoL. Its place in the therapeutic strategy is to be determined, considering affordability.

Sodium-glucose cotransporter 2 inhibitors for transthyretin amyloid cardiomyopathy: Analyses of short-term efficacy and safety

AIMS

Despite their potential, sodium-glucose cotransporter 2 inhibitors (SGLT2i) have not been well-studied in transthyretin amyloid cardiomyopathy (ATTR-CM) as randomized trials have excluded patients with this morbid disease. We performed a retrospective study assessing the short-term efficacy and safety of SGLT2i in ATTR-CM.

METHODS AND RESULTS

We screened consecutive patients seen at a tertiary care centre and identified 87 ATTR-CM patients treated with SGLT2i and 95 untreated control patients. Endpoints included changes in weight, loop diuretic dose, and cardiac/renal biomarkers. The median age of the overall population was 79 (interquartile range [IQR] 11) years. Nearly 90% of patients were male, and 93% were on a transthyretin stabilizer. Control patients demonstrated generally less severe disease at baseline compared to SGLT2i-treated patients, with lower median Columbia risk score (p < 0.001). Median follow-up time was 5.6 (IQR 5.2) and 8.4 (IQR 2.1) months in the SGLT2i and control cohorts, respectively. Compared with controls, SGLT2i treatment was associated with significantly greater reductions from baseline in weight, loop diuretic dose, and uric acid during follow-up (p < 0.001). While no significant between-group differences were observed on cardiac biomarkers, estimated glomerular filtration rate was significantly reduced versus controls 1 month after SGLT2i initiation (p = 0.002), but no significant differences were observed at later timepoints. Results were similar in a propensity score-matched analysis (n = 42 per cohort). A total of 10 (11.5%) patients discontinued SGLT2i, most commonly due to genitourinary symptoms.

CONCLUSION

Sodium-glucose cotransporter 2 inhibitors were well tolerated by most patients with ATTR-CM and appeared to improve volume status and combat diuretic resistance. Randomized studies are needed to confirm these findings.

Cardiac Amyloidosis Due to Transthyretin Protein: A Review

Importance

Systemic amyloidosis from transthyretin (ATTR) protein is the most common type of amyloidosis that causes cardiomyopathy.

Observations

Transthyretin (TTR) protein transports thyroxine (thyroid hormone) and retinol (vitamin A) and is synthesized predominantly by the liver. When the TTR protein misfolds, it can form amyloid fibrils that deposit in the heart causing heart failure, heart conduction block, or arrhythmia such as atrial fibrillation. The biological processes by which amyloid fibrils form are incompletely understood but are associated with aging and, in some patients, affected by inherited variants in the TTR genetic sequence. ATTR amyloidosis results from misfolded TTR protein deposition. ATTR can occur in association with normal TTR genetic sequence (wild-type ATTR) or with abnormal TTR genetic sequence (variant ATTR). Wild-type ATTR primarily manifests as cardiomyopathy while ATTR due to a genetic variant manifests as cardiomyopathy and/or polyneuropathy. Approximately 50 000 to 150 000 people in the US have heart failure due to ATTR amyloidosis. Without treatment, heart failure due to ATTR amyloidosis is associated with a median survival of approximately 5 years. More than 130 different inherited genetic variants in TTR exist. The most common genetic variant is Val122Ile (pV142I), an allele with an origin in West African countries, that is present in 3.4% of African American individuals in the US or approximately 1.5 million persons. The diagnosis can be made using serum free light chain assay and immunofixation electrophoresis to exclude light chain amyloidosis combined with cardiac nuclear scintigraphy to detect radiotracer uptake in a pattern consistent with amyloidosis. Loop diuretics, such as furosemide, torsemide, and bumetanide, are the primary treatment for fluid overload and symptomatic relief of patients with ATTR heart failure. An ATTR-directed therapy that inhibited misfolding of the TTR protein (tafamidis, a protein stabilizer), compared with placebo, reduced mortality from 42.9% to 29.5%, reduced hospitalizations from 0.7/year to 0.48/year, and was most effective when administered early in disease course.

Conclusions and Relevance

ATTR amyloidosis causes cardiomyopathy in up to approximately 150 000 people in the US and tafamidis is the only currently approved therapy. Tafamidis slowed progression of ATTR amyloidosis and improved survival and prevented hospitalization, compared with placebo, in people with ATTR-associated cardiomyopathy.

Nanoparticles and siRNA: A new era in therapeutics?

Since its discovery in 1998, the use of small interfering RNA (siRNA) has been increasing in biomedical studies because of its ability to very selectively inhibit the expression of any target gene. Thus, siRNAs can be used to generate therapeutic compounds for different diseases, including those that are currently 'undruggable'. This has led siRNA-based therapeutic compounds to break into clinical settings, with them holding the promise to potentially revolutionise therapeutic approaches. To date, the United States Food and Drug Administration (FDA) have approved 5 compounds for treating different diseases including hypercholesterolemia, transthyretin-mediated amyloidosis (which leads to polyneuropathy), hepatic porphyria, and hyperoxaluria. This current article presents an overview of the molecular mechanisms involved in the selective pharmacological actions of siRNA-based compounds. It also describes the ongoing clinical trials of siRNA-based therapeutic compounds for hepatic diseases, pulmonary diseases, atherosclerosis, hypertriglyceridemia, transthyretin-mediated amyloidosis, and hyperoxaluria, kidney diseases, and haemophilia, as well as providing a description of FDA-approved siRNA therapies. Because of space constraints and to provide an otherwise comprehensive review, siRNA-based compounds applied to cancer therapies have been excluded. Finally, we discuss how the use of lipid-based nanoparticles to deliver siRNAs holds promise for selectively targeting mRNA-encoding proteins associated with the genesis of different diseases. Thus, siRNAs can help reduce the cellular levels of these proteins, thereby contributing to disease treatment. As consequence, a marked increase in the number of marketed siRNA-based medicines is expected in the next two decades, which will likely open up a new era of therapeutics.

Stratifying Disease Progression in Patients With Cardiac ATTR Amyloidosis

BACKGROUND

Transthyretin cardiac amyloidosis (ATTR-CA) is a progressive cardiomyopathy. The clinical course varies among individuals and there are no established measures to assess disease progression.

OBJECTIVES

The goal of this study was to assess the prognostic importance of an increase in N-terminal pro-B-type natriuretic peptide (NT-proBNP) and outpatient diuretic intensification (ODI) as markers of disease progression in a large cohort of patients with ATTR-CA.

METHODS

We evaluated landmark survival analysis based on worsening of NT-proBNP and requirement for ODI between time of diagnosis and a 1-year visit, and subsequent mortality in 2,275 patients with ATTR-CA from 7 specialist centers. The variables were developed in the National Amyloidosis Centre (NAC) cohort (n = 1,598) and validated in the external cohort from the remaining centers (n = 677).

RESULTS

Between baseline and 1-year visits, 551 (34.5%) NAC patients and 204 (30.1%) patients in the external validation cohort experienced NT-proBNP progression (NT-proBNP increase >700 ng/L and >30%), which was associated with mortality (NAC cohort: HR: 1.82; 95% CI: 1.57-2.10; P < 0.001; validation cohort: HR: 1.75; 95% CI: 1.32-2.33; P < 0.001). At 1 year, 451 (28.2%) NAC patients and 301 (44.5%) patients in the external validation cohort experienced ODI, which was associated with mortality (NAC cohort: HR: 1.88; 95% CI: 1.62-2.18; P < 0.001; validation cohort: HR: 2.05; 95% CI: 1.53-2.74; P < 0.001). When compared with patients with a stable NT-proBNP and stable diuretic dose, a higher risk of mortality was observed in those experiencing either NT-proBNP progression or ODI (NAC cohort: HR: 1.93; 95% CI: 1.65-2.27; P < 0.001; validation cohort: HR: 1.94; 95% CI: 1.36-2.77; P < 0.001), and those experiencing both NT-proBNP progression and ODI (NAC cohort: HR: 2.98; 95% CI: 2.42-3.67; P < 0.001; validation cohort: HR: 3.23; 95% CI: 2.17-4.79; P < 0.001).

CONCLUSIONS

NT-proBNP progression and ODI are frequent and consistently associated with an increased risk of mortality. Combining both variables produces a simple, universally applicable model that detects disease progression in ATTR-CA.

Towards etiological treatments in cardiomyopathies

This review proposes to look at the evolution of cardiomyopathy treatments in the light of advances in diagnostic techniques, which have enabled to move from a mechanistic to a phenotypic and then etiological approach. The article goes beyond the ejection fraction approach, and look at new therapies that target the pathophysiological pathways of cardiomyopathies, either by targeting the phenotype, or by targeting the etiology. The evolution of HCM treatments is detailed, culminating in the latest etiological treatments such as mavacamten in sarcomeric HCM, tafamidis in transthyretin cardiac amyloidosis and migalastat in Fabry disease. Myosin stimulators are reviewed in the treatment of DCM, before opening perspectives for gene therapy, which proposes direct treatment of the culprit mutation.

Advances in the diagnosis and treatment of transthyretin amyloid cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is an underrecognized cause of heart failure (HF). ATTR-CM can lead to a number of cardiovascular manifestations including HF, rhythm disturbances, and valvular disease that ultimately limit quality of life and prognosis. Due to advances in diagnostic modalities and therapeutic options, the prevalence of ATTR-CM is rising. There are several classes of medications under active investigation, though most therapies are most efficacious if instituted early on in the disease course. As such, early clinical recognition and prompt diagnosis are crucial to improving disease related outcomes. In this review, we highlight clinical manifestations of ATTR-CM as well as contemporary diagnostic and treatment approaches to the disease.

Implications of siRNA Therapy in Bone Health: Silencing Communicates

The global statistics of bone disorders, skeletal defects, and fractures are frightening. Several therapeutic strategies are being used to fix them; however, RNAi-based siRNA therapy is starting to prove to be a promising approach for the prevention of bone disorders because of its advanced capabilities to deliver siRNA or siRNA drug conjugate to the target tissue. Despite its 'bench-to-bedside' usefulness and approval by food and drug administration for five siRNA-based therapeutic medicines: Patisiran, Vutrisiran, Inclisiran, Lumasiran, and Givosiran, its use for the other diseases still remains to be resolved. By correcting the complications and complexities involved in siRNA delivery for its sustained release, better absorption, and toxicity-free activity, siRNA therapy can be harnessed as an experimental tool for the prevention of complex and undruggable diseases with a personalized medicine approach. The present review summarizes the findings of notable research to address the implications of siRNA in bone health for the restoration of bone mass, recovery of bone loss, and recuperation of bone fractures.

Molecular Therapies in Cardiovascular Diseases: Small Interfering RNA in Atherosclerosis, Heart Failure, and Hypertension

Small interfering RNA (siRNA) represents a novel, fascinating therapeutic strategy that allows for selective reduction in the production of a specific protein through RNA interference. In the cardiovascular (CV) field, several siRNAs have been developed in the last decade. Inclisiran has been shown to significantly reduce low-density lipoprotein cholesterol (LDL-C) circulating levels with a reassuring safety profile, also in older patients, by hampering proprotein convertase subtilisin/kexin type 9 (PCSK9) production. Olpasiran, directed against apolipoprotein(a) mRNA, prevents the assembly of lipoprotein(a) [Lp(a)] particles, a lipoprotein linked to an increased risk of ischemic CV disease and heart valve damage. Patisiran, binding transthyretin (TTR) mRNA, has demonstrated an ability to improve heart failure and polyneuropathy in patients with TTR amyloidosis, even in older patients with wild-type form. Zilebesiran, designed to reduce angiotensinogen secretion, significantly decreases systolic and diastolic blood pressure (BP). Thanks to their effectiveness, safety, and tolerability profile, and with a very low number of administrations in a year, thus overcoming adherence issues, these novel drugs are the leaders of a new era in molecular therapies for CV diseases.

Development of a Ready-to-Use-Type RNA Vaccine Carrier Based on an Intracellular Environment-Responsive Lipid-like Material with Immune-Activating Vitamin E Scaffolds

Because of its efficient and robust gene transfer capability, messenger RNA (mRNA) has become a promising tool in various research fields. The lipid nanoparticle (LNP) is considered to be a fundamental technology for an mRNA delivery system and has been used extensively for the development of RNA vaccines against SARS-CoV-2. We recently developed ssPalm, an environmentally responsive lipid-like material, as a component of LNP for mRNA delivery. In this study, a self-degradable unit (phenyl ester) that confers high transfection activity and an immune stimulating unit (vitamin E scaffold) for high immune activation were combined to design a material, namely, ssPalmE-Phe-P4C2, for vaccine use. To design a simple and user-friendly form of an RNA vaccine based on this material, a freeze-drying-based preparation method for producing a ready-to-use-type LNP (LNP(RtoU)) was used to prepare the LNPssPalmE-Phe. The optimization of the preparation method and the lipid composition of the LNPssPalmE-Phe(RtoU) revealed that dioleoyl-sn-glycero phosphatidylethanolamine (DOPE) was a suitable helper lipid for achieving a high vaccination activity of the LNPssPalmE-Phe(RtoU). Other findings indicated that to maintain particle properties and vaccination activity, a 40% cholesterol content was necessary. A single administration of the LNPssPalmE-Phe(RtoU) that contained mRNA-encoding Ovalbumin (mOVA-LNPssPalmE-Phe(RtoU)) demonstrated a significant suppression of tumor progression in a tumor-bearing mouse OVA-expressing cell line (E.G7-OVA). In summary, the LNPssPalmE-Phe(RtoU) is an easy-to-handle drug delivery system (DDS) for delivering mRNA antigens in immunotherapy.