Amyloid Neuropathy: From Pathophysiology to Treatment in Light-Chain Amyloidosis and Hereditary Transthyretin Amyloidosis.

Amyloid neuropathy is caused by deposition of insoluble ß-pleated amyloid sheets in the peripheral nervous system. It is most common in: (1) light-chain amyloidosis, a clonal non-proliferative plasma cell disorder in which fragments of immunoglobulin, light or heavy chain, deposit in tissues, and (2) hereditary transthyretin (ATTRv) amyloidosis, a disorder caused by autosomal dominant mutations in the TTR gene resulting in mutated protein that has a higher tendency to misfold. Amyloid fibrils deposit in the endoneurium of peripheral nerves, often extensive in the dorsal root ganglia and sympathetic ganglia, leading to atrophy of Schwann cells in proximity to amyloid fibrils and blood-nerve barrier disruption. Clinically, amyloid neuropathy is manifested as a length-dependent sensory predominant neuropathy associated with generalized autonomic failure. Small unmyelinated nerves are involved early and prominently in early-onset Val30Met ATTRv, whereas other ATTRv and light-chain amyloidosis often present with large- and small-fiber involvement. Nerve conduction studies, quantitative sudomotor axon testing, and intraepidermal nerve fiber density are useful tools to evaluate denervation. Amyloid deposition can be demonstrated by tissue biopsy of the affected organ or surrogate site, as well as bone-avid radiotracer cardiac imaging. Treatment of light-chain amyloidosis has been revolutionized by monoclonal antibodies and stem cell transplantation with improved 5-year survival up to 77%. Novel gene therapy and transthyretin stabilizers have revolutionized treatment of ATTRv, improving the course of neuropathy (less change in the modified Neuropathy Impairment Score + 7 from baseline) and quality of life. With great progress in amyloidosis therapies, early diagnosis and presymptomatic testing for ATTRv family members has become paramount. ANN NEUROL 2024;96:423-440.

How I treat AL amyloidosis.

The treatment of patients with systemic light chain (AL) amyloidosis is a challenge to hematologists. Despite its generally small size, the underlying clone causes a rapidly progressing, often devastating multiorgan dysfunction through the toxic light chains that form amyloid deposits. Clinical manifestations are deceitful and too often recognized at an irreversible stage. However, hematologists are in the unique position to diagnose AL amyloidosis at a presymptomatic stage, checking biomarkers of amyloid organ involvement in patients with monoclonal gammopathies at higher risk to develop the disease. Adequate technology and expertise are needed for a prompt and correct diagnosis, particularly for ruling out non-AL amyloidoses that are now also treatable. Therapy should be carefully tailored based on severity of organ involvement and clonal characteristics, and early and continual monitoring of response is critical. Three recent randomized clinical trials moved AL amyloidosis to evidence-based era. Above all, the daratumumab-bortezomib combination is a new standard-of-care for newly diagnosed patients, inducing rapid and deep responses that translate into high rates of organ response. The availability of new effective drugs allows to better personalize the therapy, reduce toxicity, and improve outcomes. Patients should be treated within clinical trials whenever possible.

Early diagnosis and management of cardiac amyloidosis: A clinical perspective.

Cardiac amyloidosis multidisciplinary team (MDT). We propose the creation of a multidisciplinary team (MDT) for cardiac amyloidosis in which internal medicine physicians could take a lead role in coordinating other specialists involved in patient care. Created with BioRender.com.

Novel monoclonal antibodies: A really specific therapy for light chain amyloidosis.

Light chain amyloidosis is a rare disease caused by clonal plasma cells in the bone marrow generating an excessive amount of immunoglobulin light chains. These chains misfold and produce insoluble fibrils that deposit in various organs, including the heart, kidneys, liver, nervous system, and digestive tract. Life expectancy and symptoms during the course of the disease vary depending on which and how many organs are affected. Targeted plasma cell therapy has significantly advanced the clinical management of amyloidosis, with ongoing progress. However, current clinical studies are investigating innovative targets, drug combinations and treatment strategies to improve therapeutic outcomes by minimizing adverse effects and refining patient prognosis in these challenging hematological conditions. In this paper, we review the state of the art regarding the use of anti-amyloid antibodies, as a revolutionary and innovative approach in the current scenario of amyloid treatment.

Immunoglobulin light chain amyloidosis: 2024 update on diagnosis, prognosis, and treatment.

DISEASE OVERVIEW: Immunoglobulin light chain amyloidosis is a clonal, nonproliferative plasma cell disorder in which fragments of immunoglobulin light or heavy chain are deposited in tissues. Clinical features depend on organs involved but can include heart failure with preserved ejection fraction, nephrotic syndrome, hepatic dysfunction, peripheral/autonomic neuropathy, and "atypical smoldering multiple myeloma or MGUS." DIAGNOSIS: Tissue biopsy stained with Congo red demonstrating amyloid deposits with apple-green birefringence is required for the diagnosis of AL amyloidosis. Organ biopsy is not required in 85% of patients. Verification that amyloid is composed of immunoglobulin light chains is mandatory. The gold standard is laser capture mass spectroscopy. PROGNOSIS: N-terminal pro-brain natriuretic peptide (NT-proBNP or BNP), serum troponin T(or I), and difference between involved and uninvolved immunoglobulin free light chain values are used to classify patients into four stages; 5-year survivals are 82%, 62%, 34%, and 20%, respectively. THERAPY: All patients with a systemic amyloid syndrome require therapy to prevent deposition of amyloid in other organs and prevent progressive organ failure. Current first-line therapy with the best outcome is daratumumab, bortezomib, cyclophosphamide, and dexamethasone. The goal of therapy is a ≥VGPR. In patients failing to achieve this depth of response options for consolidation include pomalidomide, stem cell transplantation, venetoclax, and bendamustine. FUTURE CHALLENGES: Delayed diagnosis remains a major obstacle to initiating effective therapy prior to the development of end-stage organ failure. Trials of antibodies to deplete deposited fibrils are underway.

AA Amyloidosis: A Contemporary View.

PURPOSE OF REVIEW: Amyloid A (AA) amyloidosis is an organ- or life-threatening complication of chronic inflammatory disorders. Here, we review the epidemiology, causes, pathogenesis, clinical features, and diagnostic and therapeutic strategies of AA amyloidosis. RECENT FINDINGS: The incidence of AA amyloidosis has declined due to better treatment of the underlying diseases. Histopathological examination is the gold standard of diagnosis, but magnetic resonance imaging can be used to detect cardiac involvement. There is yet no treatment option for the clearance of amyloid fibril deposits; therefore, the management strategy primarily aims to reduce serum amyloid A protein. Anti-inflammatory biologic agents have drastically expanded our therapeutic armamentarium. Kidney transplantation is preferred in patients with kidney failure, and the recurrence of amyloidosis in the allograft has become rare as transplant recipients have started to benefit from the new agents. The management of AA amyloidosis has been considerably changed over the recent years due to the novel therapeutic options aiming to control inflammatory activity. New agents capable of clearing amyloid deposits from the tissues are still needed.

Feasibility and safety of left bundle branch area pacing in cardiac amyloidosis. A single center experience.

BACKGROUND: Conventional right ventricle (RV) pacemaker stimulation has been associated with worse clinical outcomes in patients with cardiac amyloidosis (CA). Left bundle branch area pacing (LABPP) has been suggested as a promising alternative. We sought to assess the safety, feasibility, and outcomes of LABPP in patients with CA. METHODS: We retrospectively analyzed echocardiography and pacing parameters and clinical outcomes in 23 consecutive patients with CA and LBBAP implanted from June 2020 to October 2022. RESULTS: LBBAP was successfully performed in 22 over 23 patients (19 male, 78.6 ± 11.7 years, 20 ATTR, mean LVEF 45.5 ± 16.2%). After the procedure, 9 patients showed Qr pattern and 11 a qR pattern in V1 on ECG. Average procedure time was 67 ± 28 min. After 7.7 ± 5.2 months follow-up, no procedure-related complications had occurred. Although, a significant reduction in QRS width (p = .001) was achieved, we did not observe significant changes in LVEF and Nt ProBNP at 6 months of follow-up. Pacing parameters were stable during follow-up: LBB capture threshold and R wave amplitude were 1.0 ±  0.5 V and 10.6 ± 6.0 mV versus 0.8 ±  0.1 V, p = .21 and 10.6 ± 5.1 mV (p = .985) at follow up. CONCLUSION: LBBAP is safe and feasible pacing technique for patients with CA. LBBAP is associated with significant narrowing of QRSd without worsening in LVEF and Nt-proBNP.

Multiple myeloma complicated with light chain cast nephropathy with focal amyloidosis: A case report.

This case report describes a rare and interesting case of a patient with multiple myeloma complicated with light chain (LC) cast nephropathy and focal amyloidosis. The patient presented with acute kidney injury, anaemia and bone lesions. The diagnosis was confirmed by bone marrow biopsy, serum and urine electrophoresis and kidney biopsy. The patient was treated with isazomil, pomalidomide and dexamethasone combination chemotherapy, followed by autologous stem cell transplantation. The patient achieved clinical remission, stable renal function and improved serum lambda free LC levels. This case highlights the challenges and advances in the diagnosis and treatment of this condition.

Cardiac Amyloidosis.

Amyloidosis is a pathologic and clinical condition resulting from the accumulation of insoluble aggregates of misfolded proteins in tissues. Extracellular deposition of amyloid fibrils in the myocardium leads to cardiac amyloidosis, which is often overlooked as a cause of diastolic heart failure. Although cardiac amyloidosis was previously believed to have a poor prognosis, recent advances in diagnosis and treatment have emphasized the importance of early recognition and changed management of this condition. This article provides an overview of cardiac amyloidosis and summarizes current screening, diagnosis, evaluation, and treatment options.

Current Therapies and Future Horizons in Cardiac Amyloidosis Treatment.

PURPOSE OF REVIEW: Cardiac amyloidosis (CA) is a condition characterized by misfolding and extracellular deposition of proteins, leading to organ dysfunction. While numerous forms of CA exist, two subtypes dominate clinical prevalence: Transthyretin amyloid (ATTR) and immunoglobulin light chain amyloid. RECENT FINDINGS: The current scientific landscape reflects the urgency to advance therapeutic interventions with over 100 ongoing clinical trials. Heart failure treatment is affected by CA phenotype with poor tolerance of otherwise frequently used medications. Treating comorbidities including atrial fibrillation and valvular disease remains a challenge in CA, driven by technical difficulties and uncertain outcomes. Tafamidis is the first ATTR-stabilizer approved with a rapidly growing rate of clinical use. In parallel, various new therapeutic classes are in late-stage clinical trials including silencers, antibodies and genetic therapy. Managing CA is a critical challenge for future heart failure care. This review delineates the current standard-of-care and scientific landscape of CA therapy.

Transgenic amyloid precursor protein mouse models of amyloidosis. Incomplete models for Alzheimer's disease but effective predictors of anti-amyloid therapies.

INTRODUCTION: Amyloid precursor protein (APP) transgenic mice are models of Alzheimer's disease (AD) amyloidosis, not all of AD. Diffuse, compacted, and vascular deposits in APP mice mimic those found in AD cases. METHODS: Most interventional studies in APP mice start treatment early in the process of amyloid deposition, consistent with a prevention treatment regimen. Most clinical trials treat patients with established amyloid deposits in a therapeutic treatment regimen. RESULTS: The first treatment to reduce amyloid and cognitive impairment in mice was immunotherapy. The APP mouse models not only predicted efficacy, but presaged the vascular leakage called ARIA. The recent immunotherapy clinical trials that removed amyloid and slowed cognitive decline confirms the utility of these early APP models when used in therapeutic designs. DISCUSSION: New mouse models of AD pathologies will add to the research armamentarium, but the early models have accurately predicted responses to amyloid therapies in humans.

Advancing Renal Amyloidosis Care: The Role of Modern Diagnostic Techniques with the Potential of Enhancing Patient Outcomes.

Renal amyloidosis is a set of complex disorders characterized by the deposition of amyloid proteins in the kidneys, which causes gradual organ damage and potential kidney failure. Recent developments in diagnostic methods, particularly mass spectrometry and proteome profiling, have greatly improved the accuracy of amyloid typing, which is critical for disease management. These technologies provide extensive insights into the specific proteins involved, allowing for more targeted treatment approaches and better patient results. Despite these advances, problems remain, owing to the heterogeneous composition of amyloid proteins and the varying efficacy of treatments based on amyloid type. Access to sophisticated diagnostics and therapy varies greatly, highlighting the global difference in renal amyloidosis management. Future research is needed to investigate next-generation sequencing and gene-editing technologies, like clustered regularly interspaced short palindromic repeats (CRISPR), which promise more profound insights into the genetic basis of amyloidosis.

Re-Engineering Therapeutic Anti-Aß Monoclonal Antibody to Target Amyloid Light Chain.

Amyloidosis involves the deposition of misfolded proteins. Even though it is caused by different pathogenic mechanisms, in aggregate, it shares similar features. Here, we tested and confirmed a hypothesis that an amyloid antibody can be engineered by a few mutations to target a different species. Amyloid light chain (AL) and ß-amyloid peptide (Aß) are two therapeutic targets that are implicated in amyloid light chain amyloidosis and Alzheimer's disease, respectively. Though crenezumab, an anti-Aß antibody, is currently unsuccessful, we chose it as a model to computationally design and prepare crenezumab variants, aiming to discover a novel antibody with high affinity to AL fibrils and to establish a technology platform for repurposing amyloid monoclonal antibodies. We successfully re-engineered crenezumab to bind both Aß42 oligomers and AL fibrils with high binding affinities. It is capable of reversing Aß42-oligomers-induced cytotoxicity, decreasing the formation of AL fibrils, and alleviating AL-fibrils-induced cytotoxicity in vitro. Our research demonstrated that an amyloid antibody could be engineered by a few mutations to bind new amyloid sequences, providing an efficient way to reposition a therapeutic antibody to target different amyloid diseases.

2024 Australia-New Zealand Expert Consensus Statement on Cardiac Amyloidosis.

Over the past 5 years, early diagnosis of and new treatments for cardiac amyloidosis (CA) have emerged that hold promise for early intervention. These include non-invasive diagnostic tests and disease modifying therapies. Recently, CA has been one of the first types of cardiomyopathy to be treated with gene editing techniques. Although these therapies are not yet widely available to patients in Australia and New Zealand, this may change in the near future. Given the rapid pace with which this field is evolving, it is important to view these advances within the Australian and New Zealand context. This Consensus Statement aims to update the Australian and New Zealand general physician and cardiologist with regards to the diagnosis, investigations, and management of CA.

Standard Therapy in Cardiac Amyloidosis: What is Known, What is "Gray".

Amyloidosis is a systemic disease due to the accumulation of misfolded amyloid fibrils that damage the heart and worsen the prognosis. Heart failure (HF), a condition frequently linked with an advanced stage of this disease, is the most prevalent clinical manifestation that leads to its diagnosis. However, due to the growing awareness of the occurrence of cardiac amyloidosis (CA), it is now possible to perform an early diagnosis and have a positive impact on its natural course. This study aims to highlight the most compelling issues concerning patients' clinical management with HF and CA.

The Role of Echocardiography for the Clinical Diagnosis, Risk Stratification, and Management of Cardiac Amyloidosis.

Amyloidosis is a rare, heterogeneous group of diseases characterized by extracellular infiltration and deposition of misfolded fibrils in different organs and tissues. A timely diagnosis is important as it can improve outcome. Echocardiography has emerged as a powerful tool to prompt suspicion and refer patients to second-level evaluation to reach a definitive diagnosis. In this scenario, new echo techniques offer new insight into the cardiac amyloidosis (CA) pathophysiology and clinical course. The present review aims to describe the developments in echocardiographic assessment of patients with suspected CA and it summarizes new available echocardiographic scores able to guide a definite diagnosis.

[Cardiac amyloidosis : simplifying the diagnosis of a complex disease]. / Amyloïdose cardiaque : simplifier le diagnostic d'une maladie complexe.

Amyloidosis is a systemic infiltrative disease characterized by deposition of misfolded proteins in tissues, notably affecting the heart. According to type of protein, various types are known with the most prevalent being light-chain and transthyretin amyloidosis. Prognosis is dismal with progression to severe heart failure without disease-modifying treatment. Latter having dramatically improved over the last decade, prompt diagnosis is of paramount importance. Recognition of early signs followed by multidisciplinary approach is essential for optimal patient management.

L'amyloïdose est une maladie infiltrative systémique caractérisée par le dépôt intratissulaire de protéines. Selon l'origine de la protéine on distingue différents types d'amyloïdose, mais ce sont essentiellement l'amyloïdose à chaînes légères et celle associée à la transthyrétine qui affectent le myocarde. Le pronostic de l'amyloïdose cardiaque est sombre, évoluant vers une insuffisance cardiaque terminale en absence de traitement spécifique. Avec l'arrivée récente de thérapies pouvant ralentir l'évolution de la maladie, un diagnostic précoce est devenu primordial. La reconnaissance des signes précurseurs de la maladie et la mise en place rapide de traitements dans un centre de référence de l'amyloïdose sont essentielles pour une gestion optimale des patients.

Pathophysiology and Therapeutic Approaches to Cardiac Amyloidosis.

Often considered a rare disease, cardiac amyloidosis is increasingly recognized by practicing clinicians. The increased rate of diagnosis is in part due the aging of the population and increasing incidence and prevalence of cardiac amyloidosis with advancing age, as well as the advent of noninvasive methods using nuclear scintigraphy to diagnose transthyretin cardiac amyloidosis due to either variant or wild type transthyretin without a biopsy. Perhaps the most important driver of the increased awareness is the elucidation of the biologic mechanisms underlying the pathogenesis of cardiac amyloidosis which have led to the development of several effective therapies with differing mechanisms of actions. In this review, the mechanisms underlying the pathogenesis of cardiac amyloidosis due to light chain (AL) or transthyretin (ATTR) amyloidosis are delineated as well as the rapidly evolving therapeutic landscape that has emerged from a better pathophysiologic understanding of disease development.

Systemic Light Chain Amyloidosis, Version 2.2023, NCCN Clinical Practice Guidelines in Oncology.

Primary systemic light chain amyloidosis (SLCA) is characterized by production of light chains that get converted to amyloid fibrils with an affinity for visceral organs and causing organ dysfunction. The therapy for SLCA is directed to recovering the function of the affected organs by targeting the abnormal plasma cell clone and slowing deposition of amyloid fibrils. The NCCN Guidelines for SLCA provide recommendations for workup, diagnosis, and treatment of primary as well as previously treated SLCA.

Individualized Approach to Management of Light Chain Amyloidosis.

Systemic light chain (AL) amyloidosis is caused by a B-cell (most commonly plasma cell) clone that produces a toxic light chain that forms amyloid fibrils in tissues and causes severe, progressive organ dysfunction. The clinical presentation is protean, and patients are usually extremely frail, thus requiring careful adaptation of the treatment approach. However, the severity of organ involvement can be accurately assessed with biomarkers that allow a sharp prognostic stratification and precise tailoring of the treatment strategy. Moreover, the availability of biomarker-based response criteria also allows adjustment of the treatment approach over time. The recent completion of 3 large randomized clinical trials has offered new evidence for designing appropriate treatments. All this information has recently been integrated in the joint guidelines of the International Society of Amyloidosis and the European Hematology Association for the treatment of AL amyloidosis. Other clinical trials are underway testing new agents directed against the amyloid clone and the amyloid deposits. Our understanding of the peculiarities of the amyloid clone, as well as our ability to detect residual clonal disease and improve organ dysfunction, are also being refined and will result in more precise personalization of the treatment approach.