Current progress in CAR-based therapy for kidney disease

Despite significant breakthroughs in the understanding of immunological and pathophysiological features for immune-mediated kidney diseases, a proportion of patients exhibit poor responses to current therapies or have been categorized as refractory renal disease. Engineered T cells have emerged as a focal point of interest as a potential treatment strategy for kidney diseases. By genetically modifying T cells and arming them with chimeric antigen receptors (CARs), effectively targeting autoreactive immune cells, such as B cells or antibody-secreting plasma cells, has become feasible. The emergence of CAR T-cell therapy has shown promising potential in directing effector and regulatory T cells (Tregs) to the site of autoimmunity, paving the way for effective migration, proliferation, and execution of suppressive functions. Genetically modified T-cells equipped with artificial receptors have become a novel approach for alleviating autoimmune manifestations and reducing autoinflammatory events in the context of kidney diseases. Here, we review the latest developments in basic, translational, and clinical studies of CAR-based therapies for immune-mediated kidney diseases, highlighting their potential as promising avenues for therapeutic intervention.

Acute kidney injury during autologous stem cell transplantation in light chain amyloidosis with kidney involvement and their impact on prognosis

Acute kidney injury (AKI) is a complication related to important organ dysfunction during autologous stem cell transplantation (ASCT) in light chain (AL) amyloidosis. This study aims to validate the risk factors of AKI during different periods of ASCT and the impact of AKI on long-term outcomes. 302 patients with AL amyloidosis and kidney involvement who underwent ASCT were included. The procedures from stem cell mobilization to 30 days after transplantation were categorized into four periods: Period 0 (stem cell mobilization and harvest), Period 1 (preparation), Period 2 (conditioning and transplantation), and Period 3 (engraftment). The incidence of AKI during ASCT was 27.15% (0.66% in Period 0, 6.62% in Period 1, 15.23% in Period 2, and 6.95% in Period 3). The major causes of AKI were capillary leak syndrome in Period 0, ganciclovir or sulfamethoxazole/trimethoprim in Period 1, high-dose melphalan in Period 2, and engraftment syndrome in Period 3. AKI in different periods had distinct risk factors and predictive models. AKI was a risk factor for both kidney survival and overall survival (OS). Even recovered AKI reduced 10-year kidney survival from 91.7% to 68.4% (p = 0.002) and 10-year OS from 91.1% to 77.7% (p = 0.005).

Autologous Stem Cell Transplant in Hodgkin's and Non-Hodgkin's Lymphoma, Multiple Myeloma, and AL Amyloidosis

Human body cells are stem cell (SC) derivatives originating from bone marrow. Their special characteristics include their capacity to support the formation and self-repair of the cells. Cancer cells multiply uncontrollably and invade healthy tissues, making stem cell transplants a viable option for cancer patients undergoing high-dose chemotherapy (HDC). When chemotherapy is used at very high doses to eradicate all cancer cells from aggressive tumors, blood-forming cells and leukocytes are either completely or partially destroyed. Autologous stem cell transplantation (ASCT) is necessary for patients in those circumstances. The patients who undergo autologous transplants receive their own stem cells (SCs). The transplanted stem cells first come into contact with the bone marrow and then undergo engraftment, before differentiating into blood cells. ASCT is one of the most significant and innovative strategies for treating diseases. Here we focus on the treatment of Hodgkin's lymphoma, non-Hodgkin's lymphoma, multiple myeloma, and AL amyloidosis, using ASCT. This review provides a comprehensive picture of the effectiveness and the safety of ASCT as a therapeutic approach for these diseases, based on the currently available evidence.

Feasibility of a Novel Academic BCMA-CART (HBI0101) for the Treatment of Relapsed and Refractory AL Amyloidosis

PURPOSE

AL amyloidosis (AL) treatments are generally based on those employed for multiple myeloma. Anti-B-cell maturation antigen (BCMA) chimeric antigen receptor T (CART)-cell therapy, already approved for multiple myeloma, might be too toxic for patients with AL.

EXPERIMENTAL DESIGN

Here we describe the ex vivo applicability of a novel in-house, academic anti-BCMA CAR construct on AL primary cells, as well as the safety and efficacy in 4 patients with relapsed/refractory (RR) primary AL, treated in a phase I clinical trial (NCT04720313).

RESULTS

Three had MAYO stage IIIa cardiac involvement at enrollment. The treatment proved relatively safe, with a short and manageable grade 3 cytokine release syndrome evident in 2 patients and no neurotoxicity in any. Cardiac decompensations, observed in 2 patients, were also short and manageable. The overall hematologic response and complete response rates were observed in all patients with an organ response evident in all four. Within a median follow-up period of 5.2 (2.5-9.5) months, all 4 patients maintained their responses.

CONCLUSIONS

BCMA-CART cells provide a first proof-of-concept that this therapy is safe enough and highly efficacious for the treatment of patients with advanced, RR AL.

A Review of Cardiac amyloidosis: Presentation, Diagnosis, and Treatment

Amyloidosis is a group of disorders that can affect almost any organ due to the misfolding of proteins with their subsequent deposition in various tissues, leading to various disease manifestations based on the location. When the heart is involved, amyloidosis can manifest with a multitude of presentations such as heart failure, arrhythmias, orthostatic hypotension, syncope, and pre-syncope. Diagnosis of cardiac amyloidosis can be difficult due to the non-specific nature of symptoms and the relative rarity of the disease. Amyloidosis can remain undiagnosed for years, leading to its high morbidity and mortality due to this delay in diagnosis. Newer imaging modalities, such as cardiac magnetic resonance imaging, advanced echocardiography, and biomarkers, make a timely cardiac amyloidosis diagnosis more feasible. Many treatment options are available, which have provided new hope for this patient population. This manuscript will review the pathology, diagnosis, and treatment options available for cardiac amyloidosis and provide a comprehensive overview of this complicated disease process.

Prognostic Implication of Longitudinal Changes of Left Ventricular Global Strain After Chemotherapy in Cardiac Light Chain Amyloidosis

Aim

Cardiac involvement is the main prognostic determinant in AL amyloidosis. We sought to determine the prognostic significance of longitudinal change of left ventricular (LV) global longitudinal strain (GLS) in cardiac light chain (AL) amyloidosis patients undergoing chemotherapy.

Methods and Result

We retrospectively investigated 117 cardiac AL amyloidosis patients who underwent chemotherapy from 2005 to 2019. All patients underwent comprehensive 2D conventional transthoracic echocardiography at baseline and after completion of first-line chemotherapy. Speckle tracking analysis of images was performed offline. Absolute value of LV GLS was expressed as [LV GLS] and change of [LV GLS] after chemotherapy was expressed as Δ [LV GLS]. Clinical outcomes including cardiac response and all-cause mortality were analyzed.Baseline clinical and echocardiographic parameters were similar in patients with and without CR. Δ [LV GLS] significantly differed between the CR and non-CR groups (0.4 ± 2.8% in the CR group vs. -0.6 ± 2.5% in the non-CR group, P-value = 0.046). Δ [LV GLS] showed satisfactory predictive performance for all-cause mortality (cut-off value = 0.8%, AUC 0.643, 95% CI [0.537-0.748]). Adding Δ [LV GLS] to the Mayo stage + pre-chemotherapy [LV GLS] model showed incremental prognostic value (C-index: 0.637 vs. 0.708; Relative Integrated Discrimination Index 0.07, P-value = 0.003; Net Reclassification Improvement 0.54, P-value < 0.001). Δ [LV GLS] showed good correlation with cardiac response (AUC 0.820, 95% CI [0.737-0.904]).

Conclusion

In cardiac amyloidosis patients who underwent chemotherapy, longitudinal change of [LV GLS] after chemotherapy showed significant association with overall survival as well as cardiac response.

Comprehensive Review of AL amyloidosis: some practical recommendations

Amyloid light chain (AL) amyloidosis is among the more common and more severe of the amyloidoses usually involving the slow proliferation of a bone-marrow-residing plasma cell (PC) clone and the secretion of unstable immunoglobulin-free light chains (FLC) that infiltrate peripheral tissues and result in detrimental end-organ damage. Disease presentation is rather vague, and the hallmark of treatment is early diagnosis before irreversible end-organ damage. Once diagnosed, treatment decision is transplant-driven whereby ~20% of patients are eligible for autologous stem cell transplantation (ASCT) with or without bortezomib-based induction. In the setting of ASCT-ineligibility, bortezomib plays a central role in upfront treatment with the recent addition of daratumumab to the current emerging standard of care. In general, management of AL amyloidosis is aimed at achieving deep, durable responses with very close monitoring for early detection of relapse/refractory disease. This article provides a comprehensive review of the management of patients with AL amyloidosis including goals of therapy, current treatment guidelines in the setting of both ASCT-eligibility and ineligibility, treatment response monitoring recommendations, toxicity management, and treatment of relapse/refractory disease.

Efficacy of Chemotherapies and Stem Cell Transplantation for Systemic AL Amyloidosis: A Network Meta-Analysis

BACKGROUND/AIMS

The present Bayesian network meta-analysis (NMA) was to compare the efficacy of different chemotherapies and autologous stem cell transplantation (ASCT) in immunoglobulin light-chain (AL) amyloidosis.

METHODS

We systematically searched PubMed, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) for studies compared the rates of hematological response (HR), complete response (CR), renal response, and cardiac response in AL amyloidosis patients.

RESULTS

There were three randomized controlled trials (RCTs) and thirteen observational controlled trials (OCTs) comprising 3,402 participants enrolled for the comparisons of seven treatments: melphalan + dexamethasone (MDex), high-dose melphalan followed by ASCT, bortezomib + melphalan + dexamethasone (BMDex), thalidomide + cyclophosphamide + dexamethasone (CTD), bortezomib + dexamethasone (BDex), bortezomib + cyclophosphamide + dexamethasone (CyBorD), cyclophosphamide + lenalidomide + dexamethasone (CLD). BMDex was ranked first in the aspect of both HR and CR, CTD induced the highest rate of renal response, and BDex was possibly the best treatment for the cardiac response.

CONCLUSION

Although more data about safety and cost are needed, BMDex was recommended as the most efficient treatment for AL amyloidosis patients for enhancing the response rate for HR and CR.

Prognostic values of novel biomarkers in patients with AL amyloidosis

As cardiac involvement is the most important prognostic marker in light-chain amyloidosis (AL), revised Mayo staging for AL incorporated N-terminal pro-brain natriuretic peptide (NTproBNP) and troponin T (TnT). However, prognostic value of novel biomarkers, such as soluble suppression of tumorigenicity 2 (sST2), growth differentiation factor 15 (GDF15), or osteopontin (OPN) is unknown in AL amyloidosis. We aimed to investigate additive predictive effects of novel biomarkers for overall mortality rates of AL amyloidosis patients. Levels of sST2, GDF15, and OPN were quantified at diagnosis in a total of 73 AL amyloidosis patients at Samsung Medical Center from 2010 to 2016. The median follow-up duration of the censored cases was 18.0 (12.4–28.1) months. A total of 25 deaths occurred during the follow-up period. Two novel biomarkers, sST2 and GDF-15 showed satisfactory predictive performances for both one-year and overall survival from ROC analysis. Best cut-off values for predicting one-year mortality were selected. Elevated sST2 and GDF-15 levels showed significant incremental prognostic values in addition to NT-ProBNP and TnT for overall mortality. Patients were assigned 1 point for elevated sST2 or GDF-15. The mean values of NT-proBNP, TnT, mean LV wall thickness, and septal e′ velocity differed significantly according to the scores. Patients with higher scores showed significantly worse prognosis even in patients with advanced revised Mayo staging. Two novel biomarkers, sST2 and GDF-15, showed satisfactory prognostic value for overall survival of AL amyloidosis patients. Furthermore, sST2 and GDF-15 showed additive incremental values over conventional biomarkers and further discriminated prognosis of patients in advanced stages.

AL amyloidosis: advances in diagnostics and treatment

AL amyloidosis (light chain; previously also called primary amyloidosis) is a systemic disease characterized by an amyloid deposition process affecting many organs, and which still has unsatisfactory survival of patients. The monoclonal light chains kappa (κ) or lambda (λ) or their fragments form the fibrils that deposit and accumulate in different tissues. Renal involvement is very frequent in AL amyloidosis and can lead to the development of nephrotic syndrome followed by renal failure in some cases. AL amyloidosis ultimately leads to destruction of tissues and progressive disease. With recent advances in the treatment, the importance of an early diagnosis of amyloidosis and correct assessment of its type is high. Histologic confirmation is based on Congo red detection of amyloid deposits in tissues but AL amyloidosis must also be distinguished from other systemic forms of amyloidoses with renal involvement, such as AA amyloidosis, amyloidosis with heavy chain deposition, fibrinogen Aα or ALECT2 (leukocyte chemotactic factor 2) deposition. Immunofluorescence (IF) plays a key role here. IF on formalin-fixed paraffin-embedded tissue after protease digestion, immunohistochemistry or laser microdissection with mass spectrometry should complete the diagnosis in unclear cases. Standard treatment with melphalan and prednisolone or with cyclophosphamide and dexamethasone has been replaced with newer drugs used for the treatment of multiple myeloma—bortezomib, carfilzomib and ixazomib or thalidomide, lenalidomide and pomalidomide. High-dose melphalan supported by autologous stem cell transplantation remains the therapeutic option for patients with low-risk status. These new treatment options prolong survival from months to years and improve the prognosis in a majority of patients.

A rare case of atypical chronic lymphocytic leukaemia presenting as nephrotic syndrome

Chronic lymphocytic leukaemia (CLL) is characterised by a lymphocytosis of mature-appearing clonal CD5+, CD23+ B lymphocytes. CLL cells arise from the bone marrow and infiltrate lymphoid tissues such as lymph nodes and spleen. Presentation is usually through discovery of lymphocytosis or lymphadenopathy. Unusual presentations, especially paraneoplastic syndromes are rare. Here, we describe a rare case presenting with severe nephrotic syndrome associated with the presence of a monoclonal protein in serum. Workup for suspected plasma cell dyscrasia led instead to the diagnosis of bone marrow infiltration by atypical CLL without lymphocytosis. Renal biopsy showed a glomerulonephritis that turned out to be paraneoplastic as it went into remission after treatment for CLL. Our case shows an unusual presentation of CLL and prompts for increased awareness of lymphoproliferative disorders in the context of seemingly unrelated conditions that may be paraneoplastic in origin.

Proteasome inhibitors in AL amyloidosis: focus on mechanism of action and clinical activity

Proteasome inhibitors are the backbone in the treatment of multiple myeloma with 3 of its representatives (bortezomib, carfilzomib, and ixazomib) having already been approved. There is a different situation altogether in the treatment of amyloid light chain (AL) amyloidosis where owing to the rarity of this entity neither of these drugs has currently gained approval. Amyloid light chain plasma cells are possibly more vulnerable to bortezomib than myeloma plasmocytes because of a slightly distinct mechanism of action, which is described in depth in this manuscript. Bortezomib is highly active and rapidly effective as a single agent and even more potent in combination with dexamethasone and alkylators. Bortezomib-based regimens have become a standard part of the initial treatment of AL amyloidosis in the majority of centers. We have reviewed all available data on bortezomib in various combinations and settings. Carfilzomib seems to be effective but also toxic in these fragile patients with a high rate of cardiac events. Oral ixazomib has shown a surprisingly high efficacy with manageable toxicity and has received the Food and Drug Administration Breakthrough Therapy designation in 2014 for relapsed AL amyloidosis patients. In this review we have comprehensively described the current available knowledge of these 3 proteasome inhibitors and their use in AL amyloidosis.

Does AL amyloidosis have a unique genomic profile? Gene expression profiling meta-analysis and literature overview

Immunoglobulin light chain amyloidosis (ALA) is a plasma cell dyscrasia characterized by deposition of amyloid fibrils in various organs and tissues. The current paper is devoted to clarify if ALA has a unique gene expression profile and to its pathogenetic argumentation. The meta-analysis of ALA patients vs. healthy donors, monoclonal gammopathy of undetermined significance, smoldering and multiple myeloma patients' cohorts have revealed molecular signature of ALA consists of 256 genes representing mostly ribosomal proteins and immunoglobulin regions. This signature appears pathogenetically supported and elucidates for the first time the role of ribosome dysfunction in ALA. In summary of our findings with literature overview, we hypothesize that ALA development is associated not only with changes in genes, coding amyloidogenic protein itself, but with post-transcriptional disbalance as well. Based on our data analysis in ALA, ribosome machinery is impaired and the affected link mainly involves translational initiation, elongation and co-translational protein folding.

Burden of cytogenetically abnormal plasma cells in light chain amyloidosis and their prognostic relevance

We performed cytoplasmic fluorescence in situ hybridization assays of light chain amyloidosis (AL). In total, 234 patients were enrolled: 28 patients with AL, 24 with monoclonal gammopathy of undetermined significance (MGUS), and 182 with multiple myeloma (MM). Chromosomal abnormalities were detected in 13 of 22 (59%) AL patients without MM. All 13 patients demonstrated IGH rearrangement, and t(11;14)/IGH-CCND1 was most frequent (32%). Chromosome gain was not observed in AL patients without MM. These findings were dissimilar to findings in MGUS patients, in whom trisomy 9 was the most frequent abnormality. Of 6 AL patients with MM, 5 (83%) patients had cytogenetic abnormalities: 1q gain (4/6, 67%), gains of chromosome 9 (3/6, 50%), IGH rearrangement and RB1 (13q) deletions (2/6 each, 33%). The percentage of clonal plasma cells among total plasma cells was variable (median, 75%; range, 16-100%) for AL patients without MM, which was lower than the results for MM patients (median 100%). The overall survival of AL patients without MM was not significantly different according to the presence of cytogenetic abnormalities (P=0.510). In summary, among Korean AL patients, IGH rearrangement was the most frequent cytogenetic abnormality and cytogenetic aberration patterns differ compared with MGUS and MM patients.

The Prevalence and Management of Systemic Amyloidosis in Western Countries

BACKGROUND

Amyloidosis has been a mystery for centuries, but research of the last decennia has clarified many of the secrets of this group of diseases. A protein-based classification of amyloidosis helps to understand problems that were part of the obsolete clinical classification in primary, secondary, and familial amyloidosis. All types of amyloid are secondary to some underlying precursor-producing process: each type is caused by a misfolded soluble precursor protein that becomes deposited as insoluble amyloid fibrils.

SUMMARY

The incidence of amyloidosis is not well documented, but probably falls between 5 and 13 per million per year. Prevalence data are scarce, but one UK study indicates about 20 per million inhabitants. Amyloidosis can be localized (amyloid deposited in the organ or tissue of precursor production) or systemic (amyloid at one or more sites distant from the site of precursor production). The major systemic types of amyloidosis are AL (associated with a light chain-producing plasma cell dyscrasia), AA (associated with longstanding inflammation), wild-type ATTR (associated with normal transthyretin and old age), and hereditary ATTR (associated with a transthyretin mutation) amyloidosis. Imaging techniques, such as cardiac ultrasound, magnetic resonance imaging, bone scintigraphy, and serum amyloid P component scintigraphy, are useful both for diagnosing amyloidosis and for assessing disease severity. Serologic markers are useful for detecting organ disease and disease monitoring during follow-up. Current treatment modalities are directed against the ongoing supply of precursor proteins and thereby aim to stop further accumulation of amyloid. Novel treatment modalities, such as interference with amyloid formation and even removal of amyloid, are being studied. A well-thought and planned monitoring during follow-up helps to assess the effect of treatment and to early detect possible progression of amyloidosis.

KEY MESSAGES

Clinical management comprises histologic proof of amyloid, evidence of systemic deposition, reliable typing, precursor assessment, severity of organ disease, risk assessment and prognosis, choice of treatment, and planned monitoring during follow-up.

FACTS FROM EAST AND WEST

(1) AL amyloidosis is the most prevalent type of amyloidosis accounting for 65% of the amyloidosis-diagnosed patients in the UK and for 93% of the amyloidosis-diagnosed patients in China. The predisposition of men over women to develop AL amyloidosis might be higher in China than in Western countries (2:1 vs. 1.3:1). Both in the East and West, incidence increases with age. At the time of diagnosis, edema is twice as frequent and the proportion of renal involvement is higher in Chinese compared to Western patients. (2) Melphalan followed by autologous stem cell transplantation (ASCT) is the current standard therapy but is restricted to eligible patients. The efficacy and safety of bortezomib combined with dexamethasone were proven in Western patients and recently confirmed in a Chinese cohort. Recent studies in China and the US indicate that bortezomib induction prior to ASCT increases the response rate. Thalidomide and lenalidomide have shown benefit, but toxicity and lack of clinical evidence exclude these agents from first-line therapy. The green tea extract epigallocatechin-3-gallate is under investigation as an inhibitor of AL amyloid formation and a compound that might dissolve amyloid.

Immunomodulatory drugs in AL amyloidosis

Immunoglobulin light chain amyloidosis (AL amyloidosis) is indeed a rare plasma cell disorder, yet the most common of the systemic amyloidoses. The choice of adequate treatment modality is complicated and depends dominantly on the risk stratification of these fragile patients. Immunomodulatory drugs (IMiDs) are currently used in newly diagnosed patients as well as in salvage therapy in relapsed/refractory patients. IMiDs have a pleiotropic effect on malignant cells and the exact mechanism of their action has been described recently. Thalidomide is the most ancient representative, effective but toxic. Lenalidomide seems to be more effective, nevertheless the toxicity remains high, especially in patients with renal insufficiency. Pomalidomide is the newest IMiD used in this indication with a good balance between efficacy and tolerable toxicity and represents the most promising compound. This review is focused on the evaluation of all three representatives of IMiDs and their roles in the treatment of this malignant disorder.

Spontaneous splenic rupture following stem cell mobilization with G-CSF and plerixafor in AL amyloidosis

BACKGROUND

AL amyloidosis is a rare plasma cell dyscrasia with multiorgan involvement. Good risk patients are candidate to high dose chemotherapy and autologous stem cell transplantation. However both transplantation and stem cell collection entail significant risk in such patients. Plerixafor is a novel mobilizing agent approved for use in "poor mobilizer" patients with lymphoma and multiple myeloma; experience in systemic amyloidosis patients is limited.

CASE REPORT

We describe a case of spontaneous splenic rupture following administration of G-CSF and plerixafor in a patient with AL amyloidosis who previously underwent heart transplantation due to amyloid heart involvement.

RESULTS AND CONCLUSION

This is the first report of spontaneous splenic rupture following stem cell mobilization with G-CSF and plerixafor in AL amyloidosis. The role of plerixafor has to be established. AL amyloidosis patients undergoing stem cell mobilization need careful monitoring of signs and symptoms of spontaneous splenic rupture.

Bilateral kidney infarction due to primary Al amyloidosis: a first case report

Primary Amyloid Light-chain (AL) amyloidosis is a rare form of plasma cell dyscrasia characterized by tissue deposition of monoclonal immunoglobulin light chain. Kidney involvement is the most frequent manifestation, and patients usually present with glomerular disease.We report an exceptional case of bilateral kidney infarcts caused by AL amyloidosis. A 34-years-old man presented with progressive dyspnea, loin pain, recurrent macroscopic hematuria, and acute kidney injury. Computed tomography showed bilateral kidney infarcts.The diagnosis of AL amyloidosis was established on the kidney biopsy with the characterization of major vascular amyloid deposits that selectively stained with antilambda light chain antibody. An amyloid restrictive cardiomyopathy was also present, responsible for the life-threatening conduction disturbance, but without patent cardioembolic disease. The patient then underwent emergency heart transplantation, followed by a conventional chemotherapy with bortezomib, melphalan, and dexamethasone. More than 3 years later, the patient has subnormal renal function, a well-functioning heart transplant, and a sustained hematologic response.In addition to the very uncommon presentation, this case illustrates the tremendous progress that has occurred in the management of severe forms of AL amyloidosis.

Targeting the ubiquitin-proteasome system in heart disease: the basis for new therapeutic strategies

SIGNIFICANCE

Novel therapeutic strategies to treat heart failure are greatly needed. The ubiquitin-proteasome system (UPS) affects the structure and function of cardiac cells through targeted degradation of signaling and structural proteins. This review discusses both beneficial and detrimental consequences of modulating the UPS in the heart.

RECENT ADVANCES

Proteasome inhibitors were first used to test the role of the UPS in cardiac disease phenotypes, indicating therapeutic potential. In early cardiac remodeling and pathological hypertrophy with increased proteasome activities, proteasome inhibition prevented or restricted disease progression and contractile dysfunction. Conversely, enhancing proteasome activities by genetic manipulation, pharmacological intervention, or ischemic preconditioning also improved the outcome of cardiomyopathies and infarcted hearts with impaired cardiac and UPS function, which is, at least in part, caused by oxidative damage.

CRITICAL ISSUES

An understanding of the UPS status and the underlying mechanisms for its potential deregulation in cardiac disease is critical for targeted interventions. Several studies indicate that type and stage of cardiac disease influence the dynamics of UPS regulation in a nonlinear and multifactorial manner. Proteasome inhibitors targeting all proteasome complexes are associated with cardiotoxicity in humans. Furthermore, the type and dosage of proteasome inhibitor impact the pathogenesis in nonuniform ways.

FUTURE DIRECTIONS

Systematic analysis and targeting of individual UPS components with established and innovative tools will unravel and discriminate regulatory mechanisms that contribute to and protect against the progression of cardiac disease. Integrating this knowledge in drug design may reduce adverse effects on the heart as observed in patients treated with proteasome inhibitors against noncardiac diseases, especially cancer.

Emerging treatments for amyloidosis

Amyloidosis results from protein misfolding, and ongoing amyloid deposition can ultimately lead to organ failure and death. Historically, this is a group of diseases with limited treatment options and frequently poor prognosis. However, there are now 'targeted' therapeutics emerging in the form of stabilizers of the precursor protein, inhibitors of fibrillogenesis, fibril disruptors, and blockers of protein translation, transcription, and immunotherapy. We review many of these approaches that are currently being assessed in clinical trials.

Decreased amyloidogenicity caused by mutational modulation of surface properties of the immunoglobulin light chain BRE variable domain

Amyloid formation by immunoglobulin light chain (LC) proteins is associated with amyloid light chain (AL) amyloidosis. Destabilization of the native state of the variable domain of the LC (VL) is known to be one of the critical factors in promoting the formation of amyloid fibrils. However, determining the key residues involved in this destabilization remains challenging, because of the existence of a number of intrinsic sequence variations within VL. In this study, we identified the key residues for destabilization of the native state of amyloidogenic VL in the LC of BRE by analyzing the stability of chimeric mutants of BRE and REI VL; the latter immunoglobulin is not associated with AL amyloidosis. The results suggest that the surface-exposed residues N45 and D50 are the key residues in the destabilization of the native state of BRE VL. Point mutations at the corresponding residues in REI VL (K45N, E50D, and K45N/E50D) destabilized the native state and increased amyloidogenicity. However, the reverse mutations in BRE VL (N45K, D50E, and N45K/D50E) re-established the native state and decreased amyloidogenicity. Thus, analyses using chimeras and point mutants successfully elucidated the key residues involved in BRE VL destabilization and increased amyloidogenic propensity. These results also suggest that the modulation of surface properties of wild-type VL may improve their stability and prevent the formation of amyloid fibrils.

Twists and turns of determining amyloid type and amyloid-related organ damage: discordance and clinical skepticism in the era of proteomic typing

Systemic immunoglobulin light-chain primary amyloidosis (AL) is the most common type of systemic amyloidosis. Recent advances in AL amyloidosis include the use of definitive proteomic typing, confirming the type of amyloid in patients with two possible amyloid-forming proteins. Laser microdissection followed by mass spectrometry (LMD/MS) can correctly identify the amyloid type with over 95% sensitivity and specificity. We report the case of a 68-year-old man with a history of IgA lambda monoclonal gammopathy and peripheral neuropathy who was diagnosed with pelvic nodal and psoas amyloidosis. The amyloid was found to be AL kappa type by LMD/MS. While LMD/MS has been effective in distinguishing among AL, secondary amyloidosis and hereditary forms of amyloidosis, our case demonstrates that typing can also identify unusual instances of discordance between light chain isotypes associated with clonal processes.

Thermal stability threshold for amyloid formation in light chain amyloidosis

Light chain (AL) amyloidosis is a devastating disease characterized by amyloid deposits formed by immunoglobulin light chains. Current available treatments involve conventional chemotherapy and autologous stem cell transplant. We have recently concluded a phase III trial comparing these two treatments. AL amyloidosis patients who achieve hematological complete response (CR) do not necessarily achieve organ response regardless of the treatment they received. In order to investigate the possible correlation between amyloid formation kinetics and organ response, we selected AL amyloidosis patients from the trial with kidney involvement and CR after treatment. Six patients were selected and their monoclonal immunoglobulin light chains were characterized. The proteins showed differences in their stability and their kinetics of amyloid formation. A correlation was detected at pH 7.4, showing that less stable proteins are more likely to form amyloid fibrils. AL-T03 is too unstable to form amyloid fibrils at pH 7.4. This protein was found in the only patient in the study that had organ response, suggesting that partially folded species are required for amyloid formation to occur in AL amyloidosis.

Oral melphalan and dexamethasone grants extended survival with minimal toxicity in AL amyloidosis: long-term results of a risk-adapted approach

The combination of oral melphalan and dexamethasone is considered standard therapy for patients with light-chain amyloidosis ineligible for autologous stem cell transplantation. However, previous trials reported different rates of response and survival, mainly because of the different proportions of high-risk patients. In the present study, including a total of 259 subjects, we treated 119 patients with full-dose melphalan and dexamethasone (dexamethasone 40 mg days 1-4), and 140 patients with advanced cardiac disease with an attenuated dexamethasone schedule (20 mg). Hematologic response rates were 76% in the full-dose group and 51% in the patients receiving the attenuated schedule; the corresponding complete response rates were 31% and 12%, respectively. The median survival was 7.4 years in the full-dose group and 20 months in the attenuated-dose group. Use of high-dose dexamethasone, amino-terminal pro-natriuretic peptide type-B >1800 ng/L, a difference between involved and uninvolved free light chains of >180 mg/L, troponin I >0.07 ng/mL, and response to therapy were independent prognostic determinants. In relapsed/refractory subjects bortezomib combinations granted high hematologic response rates (79% and 63%, respectively), proving the most effective rescue treatment after melphalan and dexamethasone. In summary, melphalan plus dexamethasone was highly effective with minimal toxicity, confirming its central role in the treatment of AL amyloidosis. Future randomized trials will clarify whether bortezomib is best used in frontline combination with melphalan and dexamethasone or as rescue treatment.

Ventricular fibrillation after bortezomib therapy in a patient with systemic amyloidosis

A 64-year-old female was diagnosed with systemic amyloidosis associated with multiple myeloma. Bortezomib and dexamethasone-therapy was initiated; however, she developed lethal ventricular fibrillation (VF) and cardiac arrest after 84 hours of therapy. Cardiopulmonary resuscitation using direct current shocks with epinephrine and amiodarone was initiated but failed to receive cardiac function. Although her arterial pulsations recovered immediately after the injection of vasopressin, she died of heart failure 8 hours after the onset of VF. Cardiac amyloidosis was verified by autopsy. Although the direct association of bortezomib with lethal VF remained to be clarified in our patient, the current report emphasizes on bortezomib as a substantial risk factor for cardiomyocyte damage. The potential risk of lethal events associated with cardiac amyloidosis should be carefully considered during bortezomib treatment for patients with AL amyloidosis.

Amyloidosis: a clinical overview

Amyloidosis is the name for protein-folding diseases characterized by extracellular deposition of a specific soluble precursor protein that aggregates in the form of insoluble fibrils. The classification of amyloidosis is based on the chemical characterization of the precursor protein. Deposition of amyloid is localized or systemic. The 4 main types of systemic amyloidosis are AL, AA, ATTR, and Aβ2M type. A schematic approach is proposed for the clinical management of systemic amyloidosis. The importance of typing amyloid with confidence, the usefulness of imaging techniques, the principles of treatment, and the need for well-planned treatment monitoring during follow-up are discussed.