Newer Therapies for Amyloid Cardiomyopathy

Beta-Adrenergic Antagonist Tolerance in Amyloid Cardiomyopathy

Background:

Beta-adrenergic antagonists or blockers (BB) are a cornerstone of cardiac therapy for multiple indications. However, BB are considered relatively contraindicated in amyloid cardiomyopathy due to poor tolerance. This intolerance is hypothesized to be due to concomitant neuropathy and significant restrictive cardiomyopathy. This study analyzes the incidence and characteristics of BB tolerance in patients with amyloid cardiomyopathy.

Methods

Through a single-center retrospective chart review, patients with amyloid cardiomyopathy, confirmed by endomyocardial biopsy or technetium-99 pyrophosphate scan, were identified and clinical data was collected. Statistical methods included Chi-square test and two sample t-tests.

Results

Of 135 cardiac amyloidosis patients, 27 patients (20.0%) had no BB use, 56 patients (41.5%) were current BB users, and 52 patients (38.5%) were prior BB users. The most frequent indications for BB use were heart failure, hypertension, coronary artery disease, and arrhythmia. The most common reason for stopping BB therapy was hypotension (62.8%) followed by fatigue, bradycardia, and orthostasis. Neurologic symptoms at the initial BB prescription or most recent evaluation were not significantly different between current and prior BB users. Their cardiovascular profiles were similar by ejection fraction, wall thickness, troponin I, and brain natriuretic peptide. There was no association for BB discontinuation based on amyloid subtype, sex, or race.

Conclusion

The majority of patients with amyloid cardiomyopathy were prescribed BB, and over half of these patients still tolerated BB therapy. Current and prior BB users had similar profiles from a cardiovascular and neurologic perspective, with no association identified to predict BB discontinuation.

Immunoglobulin light chain amyloidosis diagnosis and treatment algorithm 2021

Immunoglobulin light chain amyloidosis (AL) commonly presents with nephrotic range proteinuria, heart failure with preserved ejection fraction, nondiabetic peripheral neuropathy, unexplained hepatomegaly or diarrhea, and should be considered in patients presenting with these symptoms. More importantly, patients being monitored for smoldering multiple myeloma and a monoclonal gammopathy of undetermined significance (MGUS) are at risk for developing AL amyloidosis. MGUS and myeloma patients that have atypical features, including unexplained weight loss; lower extremity edema, early satiety, and dyspnea on exertion should be considered at risk for light chain amyloidosis. Overlooking the diagnosis of light chain amyloidosis leading to therapy delay is common, and it represents an error of diagnostic consideration. Herein we provide a review of established and investigational treatments for patients with AL amyloidosis and provide algorithms for workup and management of these patients.

Clinical characteristics and prognosis of cardiac amyloidosis defined by mass spectrometry-based proteomics in an Australian cohort

Cardiac amyloidosis has a very poor prognosis, but it is the nature of the involved precursor protein that ultimately dictates treatment and survival. We report the clinical characteristics and survival of 47 cardiac amyloid patients across 2 Australian centres including 39 patients evaluated for definitive amyloid subtype utilising laser microdissection and tandem mass spectrometry (LMD-MS). A quarter of patients (n=12) were classified as wild type transthyretin amyloidosis (ATTRwt), 33 patients as light or heavy chain amyloidosis (AL or AH), and 2 as hereditary mutant transthyretin amyloidosis (ATTRv). Greater left ventricular hypertrophy (IV septum 22 vs. 15 mm, p=0.005) and history of cardiac arrhythmia (75% vs. 31%, p=0.016) were significantly associated with ATTRwt patients compared with AL/AH patients. AL patients demonstrated significantly shorter median survival compared to ATTRwt patients (3.5 vs. 37 months, (P=0.007)). New York heart association (NYHA) class III-IV symptoms or plasma cells ≥ 10% at diagnosis, were the only independent predictors of worse survival in AL patients on multivariate analysis. In the era of novel therapies for both AL amyloid and ATTR, identification of the correct amyloid subtype is essential in making therapeutic decisions and providing accurate prognostic information to patients. This article is protected by copyright. All rights reserved.

Patisiran, an RNAi therapeutic for the treatment of hereditary transthyretin-mediated amyloidosis

Hereditary transthyretin-mediated amyloidosis is a rapidly progressive, heterogeneous disease caused by the accumulation of misfolded transthyretin protein as amyloid fibrils at multiple sites, and is characterized by peripheral sensorimotor neuropathy, autonomic neuropathy and/or cardiomyopathy. Current treatment options have limited efficacy and often do not prevent disease progression. Patisiran is a novel RNA interference therapeutic that specifically reduces production of both wild-type and mutant transthyretin protein. In Phase II, III and long-term extension studies in patients with hereditary transthyretin-mediated amyloidosis, patisiran has consistently slowed or improved progression of neuropathy. In addition, the Phase III trial demonstrated significant improvements in quality of life measures and indicators of cardiomyopathy. Here, we highlight efficacy and safety data from the patisiran clinical trial programme.

Clustered Regularly Interspaced Short Palindromic Repeats-Based Genome Surgery for the Treatment of Autosomal Dominant Retinitis Pigmentosa

PURPOSE

To develop a universal gene therapy to overcome the genetic heterogeneity in retinitis pigmentosa (RP) resulting from mutations in rhodopsin (RHO).

DESIGN

Experimental study for a combination gene therapy that uses both gene ablation and gene replacement.

PARTICIPANTS

This study included 2 kinds of human RHO mutation knock-in mouse models: RhoP23H and RhoD190N. In total, 23 RhoP23H/P23H, 43 RhoP23H/+, and 31 RhoD190N/+ mice were used for analysis.

METHODS

This study involved gene therapy using dual adeno-associated viruses (AAVs) that (1) destroy expression of the endogenous Rho gene in a mutation-independent manner via an improved clustered regularly interspaced short palindromic repeats-based gene deletion and (2) enable expression of wild-type protein via exogenous cDNA.

MAIN OUTCOME MEASURES

Electroretinographic and histologic analysis.

RESULTS

The thickness of the outer nuclear layer (ONL) after the subretinal injection of combination ablate-and-replace gene therapy was approximately 17% to 36% more than the ONL thickness resulting from gene replacement-only therapy at 3 months after AAV injection. Furthermore, electroretinography results demonstrated that the a and b waves of both RhoP23H and RhoD190N disease models were preserved more significantly using ablate-and-replace gene therapy (P < 0.001), but not by gene replacement monotherapy.

CONCLUSIONS

As a proof of concept, our results suggest that the ablate-and-replace strategy can ameliorate disease progression as measured by photoreceptor structure and function for both of the human mutation knock-in models. These results demonstrate the potency of the ablate-and-replace strategy to treat RP caused by different Rho mutations. Furthermore, because ablate-and-replace treatment is mutation independent, this strategy may be used to treat a wide array of dominant diseases in ophthalmology and other fields. Clinical trials using ablate-and-replace gene therapy would allow researchers to determine if this strategy provides any benefits for patients with diseases of interest.

Seven factors predict a delayed diagnosis of cardiac amyloidosis

INTRODUCTION

Diagnostic delay of cardiac amyloidosis (CAm) continues to challenge clinicians. We investigated features associated with delay and ascertained if a diagnostic delay had negative implications for the patient.

METHODS

We performed a retrospective chart review identifying 82 subjects with biopsy-proven and mass-spectrometry-identified CAm with clinical and epidemiologic data including first potential symptom of amyloidosis. Pathology slides were scored for extent of amyloid. Robust statistical analyses including generalized linear and ordered logistic regression analysis were performed.

RESULTS

There was a 22 month (median) delay in diagnosis, more pronounced (34 months) in subjects with transthyretin (ATTR) amyloidosis. Seven factors predict a delayed diagnosis including ATTR amyloid type (ratio =2.17, 95% CI 1.31-3.59), having carpal tunnel syndrome (2.13, CI 1.49-3.03) and age <70 at first symptom (1.85, CI 1.30-2.61). Individuals with delays of 1+ years had higher levels of NT proBNP (4451 vs. 2559 pg/mL, p = .016) and longer PR intervals (225 vs. 162 ms, p < .001) at the time of diagnosis.

CONCLUSIONS

Diagnostic delays negatively affect cardiac function. Of the predictive clinical features, carpal tunnel syndrome was frequent and its presence should lead to a more aggressive analysis for CAm in the appropriate clinical settings.

Immunoglobulin light chain amyloidosis diagnosis and treatment algorithm 2018

Immunoglobulin light chain amyloidosis (AL) should be considered in any patient that presents to a cancer care provider with nephrotic range proteinuria, heart failure with preserved ejection fraction, non-diabetic peripheral neuropathy, unexplained hepatomegaly or diarrhea. More importantly, patients being monitored for smoldering multiple myeloma and a monoclonal gammopathy of undetermined significance (MGUS) are at risk for developing AL amyloidosis. MGUS and myeloma patients that have atypical features, including unexplained weight loss; lower extremity edema, early satiety, and dyspnea on exertion should be considered at risk for light chain amyloidosis. Overlooking the diagnosis of light chain amyloidosis leading to therapy delay is common, and it represents an error of diagnostic consideration. Algorithms will be provided on how to evaluate patients with suspected AL amyloid as well as how to manage patients referred from other medical specialties with biopsy-proven amyloid. An organized stepwise approach to the treatment of patients with light chain amyloidosis, including established and investigational therapies, will be reviewed.

Therapeutic Strategies Targeting Inherited Cardiomyopathies

PURPOSE OF REVIEW

Cardiomyopathies due to genetic mutations are a heterogeneous group of disorders that comprise diseases of contractility, myocardial relaxation, and arrhythmias. Our goal here is to discuss a limited list of genetically inherited cardiomyopathies and the specific therapeutic strategies used to treat them.

RECENT FINDINGS

Research into the molecular pathophysiology of the development of these cardiomyopathies is leading to the development of novel treatment approaches. Therapies targeting these specific mutations with gene therapy vectors are on the horizon, while other therapies which indirectly affect the physiologic derangements of the mutations are currently being studied and used clinically. Many of these therapies are older medications being given new roles such as mexiletine for Brugada syndrome and diflunisal for transthyretin amyloid cardiomyopathy. A newer targeted therapy, the inhibitor of myosin ATPase MYK-461, has been shown to suppress the development of ventricular hypertrophy, fibrosis, and myocyte disarray and is being studied as a potential therapy in patients with hypertrophic cardiomyopathy. While this field is too large to be completely contained in a single review, we present a large cross section of recent developments in the field of therapeutics for inherited cardiomyopathies. New therapies are on the horizon, and their development will likely result in improved outcomes for patients inflicted by these conditions.

Aortic valve replacement in patients with amyloidosis

BACKGROUND

Outcome data on aortic valve replacement in patients with amyloidosis are limited. To address this issue, we reviewed our experience of patients with amyloidosis who underwent aortic valve replacement.

METHODS

We retrospectively reviewed the records of 16 patients with amyloidosis who underwent aortic valve replacement between May 2000 and February 2017.

RESULTS

The cohort comprised 11 males (69%) and 5 females (31%). The median patient age was 76 years (interquartile range [IQR], 71-82 years), and Society of Thoracic Surgeons predicted rate of mortality was 5.0% (IQR, 2.4%-8.7%). Amyloidosis type was immunoglobulin light chain in 6 patients (38%), age-related in 6 (38%), and localized in 4 (25%). The operation was surgical aortic valve replacement in 11 patients (69%) and balloon-expandable transfemoral transcatheter aortic valve insertion in the other 5. There was no procedure-related stroke, need for new-onset dialysis or pacemaker, or death within 30 days of surgery. The median length of hospital stay was 1 day (IQR, 1-2 days) in the transcatheter valve insertion group and 6 days (IQR, 6-8 days) in the surgical group (P = .002). Follow-up was available for all patients at a median of 1.9 years (IQR, 1.2-4.8 years). During the follow-up period, there were 4 deaths, all occurring >1 year after surgery.

CONCLUSIONS

Aortic valve replacement can be performed with low risk of operative morbidity and mortality in patients with amyloidosis. Transcatheter valve insertion has the advantage of reduced hospital length of stay. The 1-year survival is excellent.

Cardiac Amyloidosis and its New Clinical Phenotype: Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF) is now an emerging cardiovascular epidemic, being identified as the main phenotype observed in clinical practice. It is more associated with female gender, advanced age and comorbidities such as hypertension, diabetes, obesity and chronic kidney disease. Amyloidosis is a clinical disorder characterized by the deposition of aggregates of insoluble fibrils originating from proteins that exhibit anomalous folding. Recently, pictures of senile amyloidosis have been described in patients with HFpEF, demonstrating the need for clinical cardiologists to investigate this etiology in suspect cases. The clinical suspicion of amyloidosis should be increased in cases of HFPS where the cardio imaging methods are compatible with infiltrative cardiomyopathy. Advances in cardio imaging methods combined with the possibility of performing genetic tests and identification of the type of amyloid material allow the diagnosis to be made. The management of the diagnosed patients can be done in partnership with centers specialized in the study of amyloidosis, which, together with the new technologies, investigate the possibility of organ or bone marrow transplantation and also the involvement of patients in clinical studies that evaluate the action of the new emerging drugs.

Mechanistic basis for the recognition of a misfolded protein by the molecular chaperone Hsp90

The critical toxic species in over 40 human diseases are misfolded proteins. Their interaction with molecular chaperones such as Hsp90, which preferentially interacts with metastable proteins, is essential for the blocking of disease progression. Here we used nuclear magnetic resonance (NMR) spectroscopy to determine the three-dimensional structure of the misfolded cytotoxic monomer of the amyloidogenic human protein transthyretin, which is characterized by the release of the C-terminal β-strand and perturbations of the A-B loop. The misfolded transthyretin monomer, but not the wild-type protein, binds to human Hsp90. In the bound state, the Hsp90 dimer predominantly populates an open conformation, and transthyretin retains its globular structure. The interaction surface for the transthyretin monomer comprises the N-terminal and middle domains of Hsp90 and overlaps with that of the Alzheimer's-disease-related protein tau. Taken together, the data suggest that Hsp90 uses a mechanism for the recognition of aggregation-prone proteins that is largely distinct from those of other Hsp90 clients.

Advances in proteomic study of cardiac amyloidosis: progress and potential

INTRODUCTION

More than ten distinct forms of amyloidoses that can involve the heart have been described, classified according to which protein originates the deposits. Cardiac amyloid infiltration translates into progressive and often life-threatening cardiomyopathy, but disease severity, prognosis and treatment drastically differ according to the amyloidosis type. The notion that protein misfolding and aggregation play a more general role in human cardiomyopathies has further raised attention towards the definition of the proteotoxicity mechanisms. Areas covered: Mass spectrometry-based proteomics plays an important role as a diagnostic tool and for understanding the molecular bases of amyloid cardiomyopathies. The landscape of applications of proteomics to the study of cardiac amyloidoses and amyloid-related cardiotoxicity is summarized, with a critical synthesis of the major achievements. Expert commentary: Current strengths and limitations of proteomics in the clinical setting and in translational research on amyloid cardiomyopathy are discussed, with the foreseen potential future directions in the field.