Updates in the Diagnosis and Management of AL Amyloidosis

Monoclonal Gammopathy of Clinical Significance (MGCS) and Related Disorders: A Review and the Role of Imaging

The term monoclonal gammopathy of clinical significance (MGCS) refers to a group of symptomatic monoclonal gammopathies that do not meet the diagnostic criteria for malignant plasma cell disorders, such as multiple myeloma or Waldenström macroglobulinemia. These symptoms are attributable to the paraneoplastic effects of monoclonal immunoglobulins that occur through diverse mechanisms. The presence of symptoms distinguishes MGCS from monoclonal gammopathy of undetermined significance, which lacks significant symptomatic presentation. The presentations of MGCS are manifold, adding to the diagnostic challenge. Clinical suspicion is key for accurate and timely diagnosis. Radiologic imaging can provide pivotal information to guide the diagnosis. In this review, we discuss MGCS from a radiology perspective and highlight pertinent imaging features associated with the disorders.

The Clinical Characteristics and Prognosis of Chinese Patients with Light-Chain Amyloidosis: A Retrospective Multicenter Analysis

To retrospectively identify the critical characteristics and prognostic factors of light-chain amyloidosis. Patients and Methods: Data were collected and compared from 91 patients who were diagnosed with light-chain amyloidosis at four hospitals between January 2010 and November 2018. We analyzed the clinical characteristics and performed an overall survival (OS) analysis. Results: Patients (median age, 60 years) were diagnosed with organ involvement of the kidney (91.2%), heart (56%), liver (14.3%), soft tissue (18.7%), or gastrointestinal tract (15.4%), and 68.1% of patients had more than two organs involved. Patients were most treated with bortezomib-based regimens (56%), and only one patient had autologous stem cell transplantation (auto-ASCT). The median OS was 36.33 months and was influenced by the ECOG score, renal involvement, cardiac involvement, hepatic involvement, and persistence of positive immunofixation. Patients who received bortezomib-based treatment had a trend of favorable OS compared to those who received non-bortezomib-based treatments, but the difference was not statistically significant. Although the overall number of organs involved was not related to OS, the number of organs involved in the heart, liver and kidney was related. Multivariate analysis indicated that cardiac involvement and negative hematologic response with persistence of positive immunofixation were independent prognostic factors for OS. Conclusion: Cardiac involvement and the hematologic response to treatment were independent prognostic factors for OS in light-chain amyloidosis patients.

Multidisciplinary supportive care in systemic light chain amyloidosis

The immunoglobulin light-chain amyloidosis is a multisystemic disease which manifests by damage to the vital organs by light chain-derived amyloid fibril. Traditionally, the treatment has been directed to the underlying plasma cell clone with or without high dose chemotherapy followed by autologous stem cell transplantation using melphalan based conditioning. Now with the approval of highly tolerable anti-CD38 monoclonal antibody daratumumab based anti-plasma cell therapy in 2021, high rates of hematologic complete responses are possible even in patients who are otherwise deemed not a candidate for autologous stem cell transplantation. However, despite the progress, there remains a limitation in the strategies to improve symptoms particularly in patients with advanced cardiac involvement, those with nephrotic syndrome and autonomic dysfunction due to underlying systemic AL amyloidosis. The symptoms can be an ordeal for the patients and their caregivers and effective strategies are urgently needed to address them. The supportive care is aimed to counteract the symptoms of the disease and the effects of the treatment on involved organs’ function and preserve patients’ quality of life. Here we discuss multidisciplinary approach in a system-based fashion to address the symptom management in this dreadful disease. In addition to achieving excellent anti-plasma cell disease control, using treatment directed to remove amyloid from the vital organs can theoretically hasten recovery of the involved organs thereby improving symptoms at a faster pace. Ongoing phase III clinical trials of CAEL-101 and Birtamimab will address this question.

The Influence of Deterioration of Kidney Function on the Diagnostic Power of Laboratory Parameters Used in the Prognostic Classification of AL Amyloidosis

There is a possibility that renal dysfunction may potentially reduce the diagnostic power of the laboratory parameters Tn, NT-proBNP and sFLC levels, used in the current prognostic classification of AL amyloidosis and the diagnosis of heart involvement by amyloid. In this study, the impact of lowering the eGFR value on the usefulness of these parameters in the prognosis and diagnosis of the presence of amyloid in the myocardium was assessed in a group of 71 patients with newly diagnosed primary amyloidosis. The assessment of diagnostic power of laboratory parameters was performed on the entire study group, and in the ranges of eGFR ≥ 60 and < 60 mL/min/1.73 m². It has been proven that, with a decrease in the eGFR value, the concentrations of NT-proBNP and the κ uninvolved light chains increase significantly (p < 0.001). To assess the diagnostic power of laboratory parameters used in the diagnosis of myocardial involvement in patients with AL amyloidosis, an ROC analysis was performed. The highest values of AUC were obtained for the NT-proBNP concentration (AUC = 0.906). The lowest values of the AUC and Youden’s index were obtained for the dFLC values (AUC = 0.723), and involved κ FLC concentration (AUC = 0.613). For all compared parameters, the smallest values of the AUC were obtained for eGFR (<60 mL/min/1.73 m²). It seems that the most suitable cardiac parameter used in the prognostic classification of AL amyloidosis, independent of renal function, is TnI. It should be noted that a concentration of involved λ chains hada higher diagnostic power to assess the heart involvement, compared to the routinely used “cardiac parameters”, TnI and NT-proBNP. It can therefore be an additional parameter used to assess the presence of amyloid in the myocardium. A decrease in eGFR value influenced the change in the diagnostic cut-off points of the most analyzed laboratory parameters. Finally, it is concluded that lowering the eGFR value reduces the utility of laboratory parameters used in the prognostic classification of AL amyloidosis.

Current Updates on the Management of AL Amyloidosis

Systemic immunoglobulin light chain (AL) amyloidosis is a rare but fatal disease. It results from clonal proliferation of plasma cells with excessive production of insoluble misfolded proteins that aggregate in the extracellular matrix, causing damage to the normal architecture and function of various organs. For decades, treatment for AL amyloidosis was based mainly on therapeutic agents previously studied for its more common counterpart, multiple myeloma. As the prevalence and incidence of AL amyloidosis have increased, ongoing research has been conducted with treatments typically used in myeloma with varying success. In this review, we focus on current treatment strategies and updates to clinical guidelines and therapeutics for AL amyloidosis.

Neuromuscular amyloidosis: Unmasking the master of disguise

Amyloidosis refers to an etiologically heterogeneous group of protein misfolding diseases, pathologically characterized by extracellular amyloid fibrils producing congophillic amorphous deposits in organs and tissues, which may lead to severe organ dysfunction and mortality. Clinical presentations vary and are often nonspecific, depending on what organs or tissues are affected. In systemic amyloidosis, the peripheral nervous system is commonly affected, whereas the skeletal muscles are only rarely involved. Immunoglobulin light chain (AL) amyloidosis and hereditary transthyretin (ATTRv) amyloidosis are the most frequent types of systemic amyloidosis involving the neuromuscular system. Localized amyloidosis can occur in skeletal muscle, so-called isolated amyloid myopathy. Amyloid neuropathy typically involves small myelinated and unmyelinated sensory and autonomic nerve fibers early in the course of the disease, followed by large myelinated fiber sensory and motor deficits. The relentlessly progressive nature with motor, painful sensory and severe autonomic dysfunction, profound weight loss, and systemic features are distinct characteristics of amyloid neuropathy. Amyloid myopathy presentation differs between systemic amyloidosis and isolated amyloid myopathy. Long-standing symptoms, distal predominant myopathy, markedly elevated creatine kinase level, and lack of peripheral neuropathy or systemic features are highly suggestive of isolated amyloid myopathy. In ATTR and AL amyloidosis, early treatment correlates with favorable outcomes. Therefore, awareness of these disorders and active screening for amyloidosis in patients with neuropathy or myopathy are crucial in detecting these patients in the everyday practice of neuromuscular medicine. Herein, we review the clinical manifestations of neuromuscular amyloidosis and provide a diagnostic approach to this disorder.