Monoclonal Immunoglobulin Light Chains Research Articles

Pulmonary light chain deposition disease: a case series and literature review.

BackgroundLight chain deposition disease (LCDD) is a systemic disorder typically characterized by non-amyloid monoclonal immunoglobulin light chain deposition in tissues. LCDD is recognized as a multisystem disease, in which the kidneys and liver are often affected. However, it is rarely encountered as a localized pulmonary disease. This study set out to characterize the clinical manifestations and features of pulmonary light-chain deposition disease (PLCDD) by conducting a retrospective analysis of clinical data obtained from patients, with the aim of improving clinical understanding of PLCDD.MethodsData from inpatients diagnosed with PLCDD at Shanghai Pulmonary Hospital (Shanghai, China) between January 2010 and December 2018 were retrospectively collected and analyzed.ResultsA total of 4 PLCDD patients confirmed with PLCDD by pulmonary tissue biopsy were analyzed. All of the patients were female and were found by physical examination. Chest images of each patient’s lungs showed multiple cystic cavities with nodules. A history of Sjogren’s syndrome was present with 1 patient, 2 patients were diagnosed with Sjogren’s syndrome after surgery (including 1 diagnosed with Sjogren’s syndrome in the 8th year of follow up), and 3 patients had leukopenia. The longest follow-up period was 8 years. During the follow-up period, 2 patients developed pulmonary lesions (1 patient had an enlarged original cystic lesion in basal segment of right lower lobe 2 years after surgery, while the other developed new nodules 7 years after surgery).ConclusionsPLCDD is characterized by multiple cystic changes with nodules in both lungs and can be easily complicated by lymphoid diseases such as Sjogren’s syndrome. The clinical symptoms cannot be characterized, and the diagnosis depends on lung biopsy.

Clinical Analysis of Cardiac Involvement in 53 Patients With Multiple Myeloma Coexistent With Light Chain Amyloidosis

BackgroundWe identified 53 patients with multiple myeloma (MM) who had biopsy evidence of light chain amyloidosis (AL), and studied their cardiac involvement and outcomes. Patients and MethodsOur cohort consisted of 53 patients in whom MM and AL were initially diagnosed from July 1, 2006 to June 30, 2016.The diagnosis of MM required > 10% of clonal plasma cells in bone marrow and 1 of the CRAB symptoms, meanwhile, the diagnosis of AL must meet pathologic diagnostic criteria and monoclonal immunoglobulin light chain. Echocardiograms and cardiac biomarker such as N terminal pro B-type natriuretic peptide was used for evaluation of cardiac damage on the baseline and before every cycle of the regimen. ResultsThere were 36 men and 17 women with a median age of 59 years; their main organ involvement was kidney (72%) and heart (62%). Of these, 22 patients were treated with a bortezomib-based regimen, and the response rate was more effective than the other 21 patients who received non-bortezomib-based regimens (64% vs. 29%). The median overall survival (OS) for the total cohort was 12 months (P < .05). The median OS of the MM cohort with International Staging System stage I and II together was 34 months, which was longer than that of patients with stage III of 8 months. The median OS in Mayo stages I, II, and III was 38, 8, and 1 months, respectively (P < .05). Cardiac involvement significantly adversely affected survival (6 vs. 40 months), as did systolic blood pressure (< 90 mmHg, 3 vs. 8.5 months). ConclusionsPatients coexistent with MM and AL is rare; AL has a negative impact on survival for the total cohort. Especially, cardiovascular dysfunction caused by AL maybe a major determinant of shortening survival.

Biochemical and biophysical characterisation of immunoglobulin free light chains derived from an initially unbiased population of patients with light chain disease.

In light chain (LC) diseases, monoclonal immunoglobulin LCs are abundantly produced with the consequence in some cases to form deposits of a fibrillar or amorphous nature affecting various organs, such as heart and kidney. The factors that determine the solubility of any given LC in vivo are still not well understood. We hypothesize that some of the biochemical properties of the LCs that have been shown to correlate with amyloid fibril formation in patients also can be used as predictors for the degree of kidney damage in a patient group that is only biased by protein availability. We performed detailed biochemical and biophysical investigations of light chains extracted and purified from the urine of a group of 20 patients with light chain disease. For all samples that contained a sufficiently high concentration of LC, we quantified the unfolding temperature of the LCs, the monomer-dimer distribution, the digestibility by trypsin and the formation of amyloid fibrils under various conditions of pH and reducing agent. We correlated the results of our biophysical and biochemical experiments with the degree of kidney damage in the patient group and found that most of these parameters do not correlate with kidney damage as defined by clinical parameters. However, the patients with the greatest impairment of kidney function have light chains which display very poor digestibility by trypsin. Most of the LC properties reported before to be predictors of amyloid formation cannot be used to assess the degree of kidney damage. Our finding that poor trypsin digestibility correlates with kidney damage warrants further investigation in order to probe a putative mechanistic link between these factors.

Inherent Biophysical Properties Modulate the Toxicity of Soluble Amyloidogenic Light Chains

In light chain amyloidosis (AL), fibrillar deposition of monoclonal immunoglobulin light chains (LCs) in vital organs, such as heart, is associated with their severe dysfunction. In addition to the cellular damage caused by fibril deposition, direct toxicity of soluble prefibrillar amyloidogenic proteins has been reported, in particular, for cardiotoxicity. However, the molecular bases of proteotoxicity by soluble LCs have not been clarified. Here, to address this issue, we rationally engineered the amino acid sequence of the highly cardiotoxic LC H6 by introducing three residue mutations, designed to reduce the dynamics of its native state. The resulting mutant (mH6) is less toxic than its parent H6 to human cardiac fibroblasts and C. elegans. The high sequence and structural similarity, together with the different toxicity, make H6 and its non-toxic designed variant mH6 a test case to shed light on the molecular properties underlying soluble toxicity. Our comparative structural and biochemical study of H6 and mH6 shows closely matching crystal structures, whereas spectroscopic data and limited proteolysis indicate that H6 displays poorly cooperative fold, higher flexibility, and kinetic instability, and a higher dynamic state in its native fold. Taken together, the results of this study show a strong correlation between the overall conformational properties of the native fold and the proteotoxicity of cardiotropic LCs.

Diagnosis of haematological diseases with monoclonal gammopathy

AbstractDespite the complexity of lymphoproliferative disorders, the presence of monoclonal immunoglobulins has been providing diagnostic guidance to the haematologist for more than a century. Clinicians may be alerted for the possible presence of serum monoclonal immunoglobulins produced in excess by increased erythrocyte sedimentation rate. Thereafter the diagnosis of monoclonal gammopathy could be proven by serum protein electrophoresis followed by immunofixation to properly identify the M‐protein. In a quarter of the cases, no intact monoclonal immunoglobulin could be detected in the sera, however, free light chains produced in excess may be identified using specialized immunoassays, so called free light chain analysis.Idiopathic monoclonal gammopathy of unknown significance (MGUS) may be present in 1% of the population above age 50 and up to 10% for individuals over 80 years of age. Due to the high frequency of MGUS, between 50‐65% of all monoclonal proteins detected fall into this category and most asymptomatic patients remain undetected for many years. MGUS patients have a 1% per year chance for transformation into malignant monoclonal gammopathies. Presently, it is accepted that most multiple myeloma and amyloidosis patients have their disease developed by transformation from preexisting MGUS. Additionally, some nonmalignant hematological disease also frequently exhibit monoclonal immunoglobulin synthesis, most notably Gaucher’s disease.From the field of neoplastic hematological diseases, smouldering and symptomatic multiple myeloma as well as Waldenström’s macroglobulinaemia almost always exhibit significant amounts of serum M‐protein and/or monoclonal free light chain excess. In case of solitary plasmocytoma, primary AL amyloidosis, cryoglobulinaemia and plasma cell leukemia, the correlation with gammopathy is less strict. Monoclonal gammopathy is less common in different types of non‐Hodgkin lymphoma. Within lymphomas lymphoplasmocytic lymphoma and marginal zone lymphoma more commonly secrete monoclonal immunoglobulins, while other B‐cell lymphomas have 14% cumulative chance for specific gammopathy. In the case of B‐cell chronic lymphocytic leukemia (the most common leukemia), intact monoclonal gammopathy has a 2% appearance, while abnormal free light chains may be detected in a third of the cases. Sporadically monoclonal gammopathy may be detected in chronic myelomonocytic leukemia, refractory anaemia, large granular cell leukemia and angioimmunoblastic lymphoma. Notably, in many of these diseases, the amount of secreted monoclonal immunoglobulin and/or free light chains correlate with the tumor burden and could be used for disease monitoring, especially in indolent hematological neoplasias.

Similar Survival with Deferred Versus Salvage Autologous Stem Cell Transplant in Light Chain Amyloidosis

Background: Light chain (AL) amyloidosis is characterized by deposition of misfolded monoclonal immunoglobulin light chains leading to organ dysfunction. AL amyloidosis has traditionally been treated with agents used in multiple myeloma, primarily alkylators, proteasome inhibitors (PIs), immunomodulatory agents (IMiDs), and high-dose melphalan/autologous stem cell transplantation (ASCT). A retrospective study comparing patients with AL amyloidosis who underwent ASCT as frontline therapy ('upfront ASCT') to those undergoing ASCT following induction ('deferred ASCT') revealed that deferred ASCT was associated with prolonged overall survival (OS) compared to upfront ASCT (Afrough et al, Biol Blood Marrow Transplant, 2018). Given the number of effective new therapies for AL amyloidosis, the potential to delay ASCT after one or more lines of therapy ('salvage ASCT') is feasible. To our knowledge, transplant outcomes of AL amyloidosis patients undergoing deferred vs salvage ASCT following at least one relapse have not been reported. A retrospective chart review was conducted to compare AL amyloidosis patients receiving deferred vs salvage ASCT for progression-free survival (PFS) and overall survival (OS). The study was approved by the Institutional Review Board at Weill Cornell Medical College. Methods: Twenty-four patients with AL amyloidosis who underwent deferred or salvage ASCT between 2000-2018 were included in the analysis. Patients who underwent upfront ASCT without induction chemotherapy were excluded. Demographics and clinical parameters were extracted from the electronic medical record. PFS was calculated from date of ASCT to first relapse and OS was calculated both from date of diagnosis and date of ASCT to death. Patients were censored if lost to follow-up prior to experiencing the relevant event. PFS as well as OS of patients who underwent deferred vs salvage ASCT were compared. Log-rank tests were used to statistically evaluate differences between Kaplan-Meier PFS/OS curves. Cox proportional hazards models were used to calculate hazard ratios (HR) using deferred ASCT as the reference treatment. Results: Among the 24 patients included in this analysis, 13 underwent deferred ASCT with 1 prior line of chemotherapy (e.g., induction), and 11 underwent salvage ASCT with a median of 3 prior lines (Table 1). Ten patients had cardiac amyloidosis, 15 had renal amyloidosis, and 6 had multi-organ involvement. Induction regimens received in the deferred group are included in Table 1. Neither PFS nor OS was significantly different between patients receiving deferred vs salvage ASCT. After median follow-up of 2.9 years, median PFS in patients who received deferred ASCT was 6.5 years and not reached in those who received salvage ASCT (P=0.47), with a HR of 1.74 (95% CI, 0.38-7.85) (Figure 1A). Median OS from date of ASCT was not reached in either group after a median follow-up of 2.8 years (P=0.52), with a HR of 2.16 (95% CI, 0.19-24.04) (Figure 1B). Similarly, median OS calculated from date of diagnosis was not significantly different between deferred vs salvage ASCT (P=0.79) (Figure 1C). Conclusions: In this cohort of 24 AL amyloidosis patients, no significant differences in PFS or OS were seen between patients undergoing deferred ASCT following induction vs salvage ASCT following multiple lines of therapy. Unlike the superior OS seen with deferred vs upfront ASCT, our findings show that either deferred or salvage ASCT may be associated with comparable outcomes and suggest similar OS despite timing of transplant. However, it is important to note the small sample size and that none of our patients received daratumumab-based regimens which may have improved PFS/OS in either or both groups. There were also small differences between groups in use of maintenance (1 vs 3 patients in the deferred and salvage groups, respectively) and proportion of patients receiving higher doses of melphalan 200mg/m2 vs 140 mg/m2 (69% vs 55% in deferred and salvage groups, respectively). Nevertheless, the lack of difference seen in PFS and OS between the two groups suggests that eventual hematologic relapse and organ progression with death occur at similar time intervals despite timing of ASCT. This speaks to the point that in newly diagnosed AL amyloidosis as well as later in the disease, achieving deep responses to prevent organ progression and death regardless of timing of ASCT remains an important treatment goal. Disclosures Van Besien: Miltenyi Biotec: Research Funding. Coleman:Kite Pharmaceuticals: Equity Ownership; Pharmacyclics: Speakers Bureau; Merck: Research Funding; Gilead, Bayer, Celgene: Consultancy, Research Funding, Speakers Bureau. Niesvizky:Takeda, Amgen, BMS, Janssen, Celgene: Consultancy, Research Funding. Rosenbaum:Janssen: Research Funding; Honoraria Akcea: Other: Accordant Health.

Light chain only variant of proliferative glomerulonephritis with monoclonal immunoglobulin deposits is associated with a high detection rate of the pathogenic plasma cell clone

IgG (mainly IgG3) is the most commonly involved isotype in proliferative glomerulonephritis with monoclonal immunoglobulin deposits (PGNMID). Here we describe the first series of PGNMID with deposition of monoclonal immunoglobulin light chain only (PGNMID-light chain). This multicenter cohort of 17 patients presented with nephritic or nephrotic syndrome with underlying hematologic conditions of monoclonal gammopathy of renal significance (71%) or multiple myeloma (29%). Monoclonal immunoglobulin was identified by serum and urine immunofixation in 65% and 73%, respectively, with abnormal serum free light chain in 83%, and a detectable bone marrow plasma cell clone in 88% of patients. Renal biopsy showed a membranoproliferative pattern in most patients. By immunofluorescence, deposits were restricted to glomeruli and composed of restricted light chain (kappa in 71%) and C3, with granular appearance and subendothelial, mesangial and subepithelial distribution by electron microscopy. Proteomic analysis in four cases of kappa PGNMID-light chain revealed spectra for kappa constant and variable domains, without evidence of Ig heavy chains; spectra for proteins of the alternative pathway of complement and terminal complex were detected in three. The classical pathway was not detected in three cases. After median follow up of 70 months, the renal response was dependent on a hematologic response and occurred in six of ten patients treated with plasma cell-directed chemotherapy but none of five patients receiving other therapies. Thus, PGNMID-light chain differs from PGNMID-IgG by higher frequency of a detectable pathogenic plasma cell clone. Hence, proper recognition is crucial as anti-myeloma agents may improve renal prognosis. Activation of an alternative pathway of complement by monoclonal immunoglobulin light chain likely plays a role in its pathogenesis.

Duodenal biopsy: an unexpected confirmatory test for a patient with al-amyloidosis

SSystemic AL- amyloidosis is a disorder of protein folding in which there is extra-cellular accumulation as β pleated fibrillar deposits of monoclonal immunoglobulin light chain fragments. AL- amyloidosis is a rare clinical entity. A presentation with clinical and histological evidence of gastrointestinal amyloidosis is even rare. Here we report primary AL- amyloidosis secondary to lamda (λ) light chain myeloma in a middle-aged woman who presented with nephrotic syndrome and motor peripheral neuropathy.

Traitement de l’amylose AL

AL amyloidosis is caused by the conversion of monoclonal immunoglobulin light chains into amyloid fibrillar aggregates that deposit in tissue and lead to organ dysfunction. Diagnosis is histological and relies primarily on non-invasive biopsies, showing Congo red-positive amorphous deposits containing immunoglobulin light chains, most commonly of lambda isotype. The clinical presentation is extremely polymorphous, due to the large number of organs that can be affected by the disease. The kidneys and the heart are most frequently involved organs, in about two thirds of patients each, responsible for nephrotic syndrome and restrictive cardiomyopathy. Treatment is based on chemotherapy aimed at eliminating the medullary clone producing the pathogenic monoclonal light chains. It is guided by risk assessment, based on the serum levels of cardiac biomarkers. Its effectiveness must be regularly assessed by the serum free light chain assay. Current reference regimens combine an alkylating agent, with high doses of dexamethasone and most often a proteasome inhibitor. They are effective in the majority of patients. The overall prognosis depends on the importance of the initial severity of organ involvement, particularly the heart, and is strongly influenced by the haematological response. The treatment must be rapidly modified in non-responders, especially in those with severe cardiac disease, with the introduction of immunomodulatory drugs and antibodies targeting plasma cells. However, effective therapies for patients with the more severe amyloid cardiopathy are an unmet need. Strategies directly accelerating the removal of amyloid deposits, despite disappointing preliminary results, could further improve the prognosis of this disease.

Cryo-EM structure of cardiac amyloid fibrils from an immunoglobulin light chain AL amyloidosis patient

Systemic light chain amyloidosis (AL) is a life-threatening disease caused by aggregation and deposition of monoclonal immunoglobulin light chains (LC) in target organs. Severity of heart involvement is the most important factor determining prognosis. Here, we report the 4.0 Å resolution cryo-electron microscopy map and molecular model of amyloid fibrils extracted from the heart of an AL amyloidosis patient with severe amyloid cardiomyopathy. The helical fibrils are composed of a single protofilament, showing typical 4.9 Å stacking and cross-β architecture. Two distinct polypeptide stretches (total of 77 residues) from the LC variable domain (Vl) fit the fibril density. Despite Vl high sequence variability, residues stabilizing the fibril core are conserved through different cardiotoxic Vl, highlighting structural motifs that may be common to misfolding-prone LCs. Our data shed light on the architecture of LC amyloids, correlate amino acid sequences with fibril assembly, providing the grounds for development of innovative medicines.

Autologous Hematopoietic Cell Transplantation Versus Chemotherapy Alone for Immunoglobulin Light Chain Amyloidosis: A Retrospective Study

IntroductionImmunoglobulin light chain (AL) amyloidosis is caused by the deposition of monoclonal immunoglobulin light chains, for which autologous hematopoietic cell transplantation (AHCT) is one of the most effective therapies. In small studies comparing AHCT with chemotherapy alone, AHCT was associated with better survival. Patients and MethodsIn this study, we compared the outcomes of AHCT with those of chemotherapy alone in 232 patients. We retrospectively reviewed the outcomes in 74 patients who underwent AHCT with those of 158 patients treated only with chemotherapy. ResultsThe median event-free survival (EFS) (73 vs. 9 months; P < .001) and overall survival (OS) (not achieved vs. 39 months; P < .001) were superior in the AHCT group versus those in the chemotherapy group. On multivariate analysis, AHCT was significantly associated with better EFS (hazard ratio, 0.410; 95% confidence interval, 0.241-0.697; P = .0010) and OS (hazard ratio, 0.313; 95% confidence interval, 0.155-0.636; P = .0013) than chemotherapy alone. Even when patients with severe findings (mean left ventricular thickness > 12 mm, brain natriuretic peptide level > 400 pg/mL, and creatinine level > 2.0 mg/dL) and elderly patients (age > 65 years) were excluded, both EFS and OS were significantly better in the AHCT group than in the chemotherapy group upon univariate and multivariate analyses. ConclusionAHCT yielded better EFS and OS than chemotherapy alone in patients with AL amyloidosis. AHCT should be considered for eligible patients.

A Substantial Structural Conversion of the Native Monomer Leads to in-Register Parallel Amyloid Fibril Formation in Light-Chain Amyloidosis.

Amyloid light-chain (AL) amyloidosis is a rare disease in which plasma-cell-produced monoclonal immunoglobulin light chains misfold and become deposited as fibrils in the extracellular matrix. λ6 subgroup light chains are particularly fibrillogenic, and around 25 % of amyloid-associated λ6 light chains exist as the allotypic G24R variant that renders the protein less stable. The molecular details of this process, as well as the structures of the fibrils, are unknown. We have used solid-state NMR to investigate different fibril polymorphs. The secondary structures derived from NMR predominantly show β-strands, including in former turn or helical regions, and provide a molecular basis for previously identified fibrillogenic hotspots. We have determined, by using differentially 15 N:13 C-labeled samples, that the β-strands are stacked in-register parallel in the fibrils. This supramolecular arrangement shows that the native globular folds rearrange substantially upon fibrillization, and rules out the previously hypothesized fibril formation from native monomers.

Classification of Plasma Cell Disorders by 21 Tesla Fourier Transform Ion Cyclotron Resonance Top-Down and Middle-Down MS/MS Analysis of Monoclonal Immunoglobulin Light Chains in Human Serum.

The current five-year survival rate for systemic AL amyloidosis or multiple myeloma is ∼51%, indicating the urgent need for better diagnosis methods and treatment plans. Here, we describe highly specific and sensitive top-down and middle-down MS/MS methods owning the advantages of fast sample preparation, ultrahigh mass accuracy, and extensive residue cleavages with 21 telsa FT-ICR MS/MS. Unlike genomic testing, which requires bone marrow aspiration and may fail to identify all monoclonal immunoglobulins produced by the body, the present method requires only a blood draw. In addition, circulating monoclonal immunoglobulins spanning the entire population are analyzed and reflect the selection of germline sequence by B cells. The monoclonal immunoglobulin light chain FR2-CDR2-FR3 was sequenced by database-aided de novo MS/MS and 100% matched the gene sequencing result, except for two amino acids with isomeric counterparts, enabling accurate germline sequence classification. The monoclonal immunoglobulin heavy chains were also classified into specific germline sequences based on the present method. This work represents the first application of top/middle-down MS/MS sequencing of endogenous human monoclonal immunoglobulins with polyclonal immunoglobulins background.

Identification of two principal amyloid-driving segments in variable domains of Ig light chains in systemic light-chain amyloidosis

Systemic light-chain amyloidosis (AL) is a human disease caused by overexpression of monoclonal immunoglobulin light chains that form pathogenic amyloid fibrils. These amyloid fibrils deposit in tissues and cause organ failure. Proteins form amyloid fibrils when they partly or fully unfold and expose segments capable of stacking into β-sheets that pair and thereby form a tight, dehydrated interface. These structures, termed steric zippers, constitute the spines of amyloid fibrils. Here, using a combination of computational (with ZipperDB and Boston University ALBase), mutational, biochemical, and protein structural analyses, we identified segments within the variable domains of Ig light chains that drive the assembly of amyloid fibrils in AL. We demonstrate that there are at least two such segments and that each one can drive amyloid fibril assembly independently of the other. Our analysis revealed that peptides derived from these segments form steric zippers featuring a typical dry interface with high-surface complementarity and occupy the same spatial location of the Greek-key immunoglobulin fold in both λ and κ variable domains. Of note, some predicted steric-zipper segments did not form amyloid fibrils or assembled into fibrils only when removed from the whole protein. We conclude that steric-zipper propensity must be experimentally validated and that the two segments identified here may represent therapeutic targets. In addition to elucidating the molecular pathogenesis of AL, these findings also provide an experimental approach for identifying segments that drive fibril formation in other amyloid diseases.

Znaczenie oceny minimalnej choroby resztkowej w amyloidozie AL

Light chain amyloidosis (AL amyloidosis) is a systemic disease leading to organ damage due to deposition of amyloid fibers arising from accumulation of amyloid precursors – monoclonal immunoglobulin light chains produced by clonal bone marrow plasmocytes. The aim of AL amyloidosis therapy is the inhibition amyloidogenic immunoglobulin light chains, what should result in stabilization or often even improvement of involved organs’ function. Treatment effectiveness evaluation is based on hematological and organ response. Despite achievement of complete hematological remission, in some of the patients even a trace number of plasmocytes persisting following treatment may lead to production of low amount of monoclonal immunoglobulins capable of deepening organ damage. These plasmocytes remain undetectable to routine diagnostic approaches and are regarded as minimal residual disease (MRD). Considering the results of the so far published research, it is possible that MRD assessment based on flow cytometric technique may constitute a basic tool of response assessment of AL amyloidosis treatment in the future. In this publication the methodology and results of latest research concerning MRD assessment in AL amyloidosis are presented.

Diagnostyka i leczenie amyloidozy AL

Light chain amyloidosis (AL amyloidosis) is a disease in which monoclonal immunoglobulin light chains, produced by clonal plasma cells are deposited extracellularly in the form of misfolded, insoluble protein complexes known as amyloid. This disease is a heterogeneous condition, due to the organ tropism, which varies among patients. Heart involvement prevails (80% of patients), whereas kidneys, liver and nervous system may be also involved. To diagnose AL amyloidosis, amyloid should be detected by staining tissue samples with Congo red, and the amyloid typing should reveal the immunoglobulin light chain character of the amyloid fibrils. The therapy usually focuses on the elimination of clonal plasma cells. Assigning the patient to the proper risk group (low, intermediate, high) is crucial. For younger patients of the low-risk group, high-dose melphalan with autologous hematopoietic stem cell transplantation (auto-HSCT) with optional bortezomib-based consolidation treatment should be considered. For the most numerous (70% of patients), intermediate-risk group, MDex (melphalan, dexamethasone), as well as bortezomib-based therapies should be given. Patients in the high-risk group should undergo a chemotherapy with reduced intensity. Refractory disease can be treated with IMIDs (immunomodulatory drugs), as well as new-generation proteasome inhibitors, bendamustine and monoclonal antibodies.

Abstract 3572: CAR T-cells targeting the kappa myeloma antigen for the treatment of multiple myeloma

Abstract This study describes the development of highly specific and effective CAR T-cells expressing novel Chimeric Antigen Receptors targeting the Kappa Myeloma Antigen. Multiple myeloma (MM) is an incurable malignancy of differentiated plasma cells accompanied by severe bone lesions, cytopenia and hypercalcemia. The majority of MM patients produce excess monoclonal immunoglobulin and/or isotype-restricted free light chains (FLC). The monoclonal antibody KappaMab (kMAb-previously-MDX-1097) binds to a unique conformational epitope on the Kappa Myeloma Antigen (KMA). KMA consists of kFLC that is not associated with Ig heavy chain but is non-covalently associated with sphingomyelin on the cell membrane. KMA is present on k-restricted MM, some k-type lymphomas and B cells associated with Waldenstroms macroglobulinemia and not present on normal B cells, immune cells or normal human tissue. The restricted expression of KMA makes it an ideal target and the unique specificity of KMAb suggests that this antibody is an excellent candidate for the development of a novel treatment for myeloma patients.The scFv gene from the kMAb was fused with the co-stimulatory domains from either CD28 or CD137 (41BB), along with the activation domain of the CD3z; subunit to construct several second generation CARs in the piggyBac transposon vector. In addition, a novel chimeric construct of KMA fused to mCherry was designed, to enable the creation of stable antigen presenting cell lines. Transfected CD3+Tcells were enriched and expanded using irradiated autologous PBMCs and the irradiated KMA-mCherry cell line with the addition of 200IU of IL-15 every 48 hours. After a three week expansion, the CAR T-cells were phenotyped and analysed for functional specificity. Release of IFN-γ upon co-culture with KMA+ or KMA- cells indicated target specific activation. The potency of the CAR T-cells was confirmed in cytotoxicity assays, using 51Cr labelled cells. Pre-clinical data indicated that the KM.CAR T-cell containing the CD8 spacer was the most efficacious among all the KM.CAR T-cells generated, even when there were moderate levels of antigen presentation. The CD28 co-stimulatory domain containing KM.CAR T-cells expressed and expanded better than the ones containing the 41BB co-stimulatory domain. All the KM.CAR T-cells were effective in clearing target cells that expressed KMA. There was a mix of central and effector memory cells at the end of culture which indicated a potential for long term survival and function in vivo. Most of the KM.CAR T-cells showed negligible expression of the exhaustion marker PD-1. Myeloma is becoming the next haematological malignancy after leukaemia to demonstrate phenomenal response rates to CAR therapy. Our in vitro data indicates that the KM.CAR T-cell is likely to be effective in kappa restricted myeloma patients. In vivo testing of these CAR T-cells in a Rag2-/- myeloma mouse model system is currently underway. Citation Format: Kavitha Gowrishankar, Rosanne Dunn, David Gottlieb, Kenneth Micklethwaite. CAR T-cells targeting the kappa myeloma antigen for the treatment of multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3572.

Phenotypic plasticity of mesenchymal stem cells is crucial for mesangial repair in a model of immunoglobulin light chain-associated mesangial damage

ABSTRACTMesangiopathies produced by glomerulopathic monoclonal immunoglobulin light chains (GLCs) acting on the glomerular mesangium produce two characteristic lesions: AL-amyloidosis (AL-Am) and light chain deposition disease (LCDD). In both cases, the pathology is centered in the mesangium, where initial and progressive damage occurs. In AL-Am the mesangial matrix is destroyed and replaced by amyloid fibrils and in LCDD, the mesangial matrix is increased and remodeled. The collagen IV rich matrix is replaced by tenascin. In both conditions, mesangial cells (MCs) become apoptotic as a direct effect of the GLCs.MCs were incubated in-vitro with GLCs and animal kidneys were perfused ex-vivo via the renal artery with GLCs, producing expected lesions, and then mesenchymal stem cells (MSCs) were added to both platforms. Each of the two platforms provided unique information that when put together created a comprehensive evaluation of the processes involved. A “cocktail” with growth and differentiating factors was used to study its effect on mesangial repair.MSCs displayed remarkable phenotypic plasticity during the repair process. The first role of the MSCs after migrating to the affected areas was to dispose of the amyloid fibrils (in AL-Am), the altered mesangial matrix (in LCDD) and apoptotic MCs/debris. To accomplish this task, MSCs transformed into facultative macrophages acquiring an abundance of lysosomes and endocytotic capabilities required to engage in phagocytic functions. Once the mesangial cleaning was completed, MSCs transformed into functional MCs restoring the mesangium to normal. “Cocktail” made the repair process more efficient.

Cardiac amyloidosis

Systemic amyloidosis comprises an uncommon group of disorders caused by the extracellular deposition of misfolded proteins in various organs. Cardiac amyloid deposition, causing an infiltrative/restrictive cardiomyopathy, is a frequent feature of amyloidosis and a major determinant of survival. It may be the presenting feature of the disease or may be identified while investigating a patient presenting with other organ involvement. The need for a high index of suspicion and the critical importance of precise biochemical typing of the amyloid deposits is paramount in light of recent therapeutic advances that can significantly improve prognosis. Most cases of cardiac amyloidosis are of either transthyretin type, which may be acquired in older individuals or inherited in younger patients, or acquired monoclonal immunoglobulin light chain (AL) type. This article aims to review recent developments in diagnosis and management of cardiac amyloidosis.

Influence of a Single Point Mutation in the Constant Domain of the Bence-Jones Protein bif on Its Aggregation Properties.

Multiple myeloma nephropathy occurs due to the aggregate formation by monoclonal immunoglobulin light chains (Bence-Jones proteins) in kidneys of patients with multiple myeloma. The mechanism of amyloid deposit formation is still unclear. Earlier, the key role in the fibril formation has been assigned to the variable domains that acquired amyloidogenic properties as a result of somatic mutations. However, fibril formation by the Bence-Jones protein BIF was found to be the function of its constant domain. The substitution of Ser177 by Asn in the constant domain of the BIF protein is most likely an inherited than a somatic mutation. To study the role of this mutation in amyloidogenesis, the recombinant Bence-Jones protein BIF and its mutant with the N177S substitution typical for the known immunoglobulin Cκ allotypes Km1, Km1,2, and Km3 were isolated. The morphology of aggregates formed by the recombinant proteins under conditions similar to those occurring during the protein transport in bloodstream and its filtration into the renal glomerulus, in the distal tubules, and in the proximal renal tubules was analyzed by atomic force microscopy. The nature of the aggregates formed by BIF and its N177S mutant during incubation for 14 days at 37°C strongly differed and depended on both pH and the presence of a reducing agent. BIF formed fibrils at pH 7.2, 6.5, and 10.1, while the N177S mutant formed fibrils only at alkaline pH 10.1. The refolding of both proteins in the presence of 5 mM dithiothreitol resulted in the formation of branched structures.