Monoclonal immunoglobulin crystalline nephropathies.

Monoclonal Ig crystalline nephropathies are rare lesions resulting from precipitation of monoclonal Igs in the kidney as crystalline inclusions. They can be categorized into lesions with predominant intracellular crystals (light chain [LC] proximal tubulopathy, LC crystal-storing histiocytosis, and LC crystalline podocytopathy) and lesions with predominant extracellular crystals (crystalglobulin-induced nephropathy and crystalline variant of LC cast nephropathy). The majority of these lesions are associated with low tumor burden lymphoproliferative disorders, with the exception of crystalline variant of LC cast nephropathy. Extrarenal involvement (e.g., skin and cornea) is frequent. Kidney biopsy is the cornerstone for diagnosis, which often requires electron microscopy and antigen retrieval. A thorough hematologic workup and evaluation of extrarenal involvement is mandatory for management. Treatment of these lesions is with clone-directed therapy, with the goal of achieving hematologic very good partial response or complete response, which preserves or improves kidney function. In vitro and in vivo studies, animal models, and novel sequencing techniques have been invaluable tools to understand the pathogenesis of LC proximal tubulopathy and can be used to increase our limited knowledge of the pathogenesis of the other monoclonal Ig crystalline nephropathies. This review provides an update on the pathology, renal and hematologic characteristics, extrarenal manifestations, prognosis, treatment, and pathogenesis of monoclonal Ig crystalline nephropathies.

Improvement of Light Chain Proximal Tubulopathy without Crystals in IgGλ-type Monoclonal Gammopathy of Undetermined Significance Using Bortezomib and Dexamethasone.

A 70-year-old woman with acute kidney injury, a high serum Creatinine (Cr) level (3.91 mg/dL), and proteinuria (protein/Cr ratio 1.59 g/gCr) was admitted. Serum IgG λ-type and urinary λ-type M proteins were observed. A bone marrow examination indicated monoclonal gammopathy of undetermined significance (MGUS). A renal biopsy showed distended proximal tubular cells, and immunofluorescence identified tissue positive for proximal tubular cell λ light chains. Electron microscopy identified fibril-like structures in the lysosomes. The patient was diagnosed with light chain proximal tubulopathy without crystals in IgG λ-type MGUS and treated with bortezomib and dexamethasone therapy, which improved her renal function.

Identifying therapeutic monoclonal antibodies using target protein collision electrophoresis reflex assay to separate the wheat from the chaff.

Monoclonal gammopathies are characterized by the presence of monoclonal immunoglobulins, also known as M-proteins. Therapeutic monoclonal antibodies (t-mAbs) can interfere in laboratory assays used to monitor the state of disease, such as serum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE). To establish a correct interpretation of IFE, Target protein-Collision Immunofixation Electrophoresis Reflex Assay (T-CIERA) was developed to identify t-mAbs in IFE. Here we demonstrate that T-CIERA is applicable to a wide variety of t-mAbs for which the target protein is commercially available. Moreover, the shift observed was characteristic for each t-mAb, and T-CIERA enabled the identification of multiple t-mAbs sharing a common target protein. Additionally, the lower limit of detection (LLOD) was determined objectively, and T-CIERA demonstrated an adequate LLOD for all tested t-mAbs. Furthermore, T-CIERA was also successfully applied to serum samples obtained from patients receiving daratumumab, isatuximab, elotuzumab, and durvalumab treatment. In conclusion, T-CIERA is a suitable reflex assay for identifying a wide variety of t-mAbs, including those for which no commercial assay is available to deal with their interference. Moreover, CD38-CIERA could serve as an alternative or complementary test to the commercially available Hydrashift assay kits. T-CIERA would enable laboratories without mass spectrometry equipment and expertise in this area to distinguish between drug and disease to improve clinical response monitoring and diagnosis of monoclonal gammopathies.

Acquired von willebrand syndrome secondary to monoclonal gammopathy of undetermined significance: long-term remission after treatment with bortezomib.

Monoclonal gammopathy of undetermined significance (MGUS) is a plasma cell disorder that can precede the diagnosis of multiple myeloma. MGUS is characterized by the presence of a monoclonal paraprotein without evidence of multiple myeloma or other lymphoplasmacytic malignancies. Even though MGUS is an asymptomatic condition that does not require management strategies other than periodic follow-up to prevent complications, secondary nonmalignant diseases may arise, requiring control of the plasma cell clone. Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder that occurs in patients with no prior personal or family history of bleeding. It is associated with several other disorders, such as neoplasia, mainly hematological (including MGUS and other lymphoproliferative disorders), autoimmune, infectious and cardiac diseases. At diagnosis, patients usually present with cutaneous and mucosal bleeding, including gastrointestinal bleeding. Here, we report a case of a patient with MGUS who developed AVWS after one year of follow-up. The patient was refractory to glucocorticoids and cyclophosphamide and achieved remission only after monoclonal paraprotein was eradicated following treatment with bortezomib and dexamethasone. Our report sdemonstrates that, for refractory cases, eradication of the monoclonal paraprotein may be necessary to treat bleeding complications due to MGUS-associated AVWS.

A feline case of multiple myeloma treated with bortezomib.

BACKGROUND: Multiple myeloma (MM) is an uncommon neoplasm in cats. There is no established standard of treatment due to the rare occurrence of this disease in cats. Bortezomib is a proteasome inhibitor that serves as the first-line drug for MM in humans, but its effectiveness currently is unknown in feline MM. We present here the case report of a feline MM that exhibited a favorable response to bortezomib. CASE PRESENTATION: The case was an 11-year-old non-castrated male domestic cat with light-chain MM presenting with clinical symptoms (anorexia, fatigue, and vomiting), mild azotemia, and pancytopenia. The cat failed on melphalan with prednisolone (MP), so bortezomib (Velcade) was initiated on Day 88. A total of 6 cycles of the treatment was performed, with each treatment cycle consisting of twice-weekly subcutaneous administration for 2 weeks followed by a 1-week rest. The dose of bortezomib was 0.7 mg/m2 for first week and 1.0 mg/m2 for second week in the first cycle. A dose of 0.7 mg/m2 was used for subsequent cycles. Prednisolone was used concomitantly in the first 2 cycles. Following treatment with bortezomib, clinical symptoms disappeared and a decrease in serum globulin and recovery of pancytopenia were noted. A monoclonal gammopathy, overproduction of serum immunoglobulin light chain, and Bence-Jones proteinuria that existed at diagnosis were undetectable on Day 123. A monoclonal gammopathy also was not detectable at the end of the bortezomib treatment (Day 213). Anorexia, fatigue, and marked bone marrow toxicity were experienced when bortezomib was administrated at a dose of 1.0 mg/m2, while no recognizable toxicity was observed at a dose of 0.7 mg/m2 throughout the treatment period. The case was placed on follow-up and there was no evidence of relapse as of Day 243. CONCLUSIONS: Bortezomib was effective and durable for the treatment of this case of feline MM after failure with MP. Bortezomib was well-tolerated in this cat at a dose of 0.7 mg/m2, but not at 1.0 mg/m2. Bortezomib appears to be a drug worthy of further study for the treatment of feline MM.

Successful use of lenalidomide to treat refractory acquired von Willebrand disease associated with monoclonal gammopathy.

Acquired von Willebrand syndrome (AVWS) is a rare hematologic disorder characterized by quantitative or qualitative defects of von Willebrand factor (vWF), a protein crucial for normal hemostasis. AVWS has been described in association with several pathologic entities with varied mechanisms. Among these, lymphoproliferative disorders are the most common, with monoclonal gammopathy of undetermined significance (MGUS) being the most frequently reported. AVWS in this setting is commonly associated with the development of bleeding that is clinically challenging to manage due to accelerated clearance of vWF, limiting the utility of many conventional treatment modalities such as DDAVP or vWF/FVIII. We report a case of a 43-year-old male who was sent to our institution for new-onset easy bruising and laboratories concerning for von Willebrand disease (vWD). Further diagnostic workup revealed evidence of an IgG monoclonal gammopathy and findings suggestive of vWF inhibition. Ultimately, he was found to have monoclonal gammopathy of clinical significance (MGCS)-associated AVWS refractory to conventional treatment but responsive to lenalidomide and dexamethasone. This case suggests that lenalidomide may be suitable for patients with AVWS secondary to MGCS.

Efficacy of rituximab in anti-myelin-associated glycoprotein demyelinating polyneuropathy: Clinical, hematological and neurophysiological correlations during 2 years of follow-up.

BACKGROUND AND PURPOSE: We evaluated the clinical and neurophysiological efficacy of rituximab (RTX) in a neurophysiologically homogeneous group of patients with monoclonal gammopathy and immunoglobulin M (IgM) anti-myelin-associated glycoprotein antibody (anti-MAG) demyelinating polyneuropathy. METHODS: Twenty three anti-MAG-positive polyneuropathic patients were prospectively evaluated before and for 2 years after treatment with RTX 375 mg/m2 . The Inflammatory Neuropathy Cause and Treatment (INCAT) disability scale (INCAT-ds), modified INCAT sensory score (mISS), Medical Research Council sum score, Patients' Global Impression of Change scale were used, IgM levels were assessed and extensive electrophysiological examinations were performed before (T0) and 1 year (T1) and 2 years (T2) after RTX treatment. RESULTS: At T1 and T2 there was a significant reduction from T0 both in mISS and in INCAT-ds, with a p value < 0.001 in the inferential Friedman's test overall analysis. Ulnar nerve Terminal Latency Index and distal motor latency significantly changed from T0 to T1 and in the overall analysis (p = 0.001 and p = 0.002), and ulnar nerve sensory nerve action potential (SNAP) amplitude was significantly increased at T2 from T1, with a p value < 0.001 in the overall analysis. Analysis of the receiver-operating characteristic curves showed that a 41.8% increase in SNAP amplitude in the ulnar nerve at T2 from T0 was a fair predictor of a mISS reduction of ≥2 points (area under the curve 0.85; p = 0.005; sensitivity: 90.9%, specificity: 83.3%). CONCLUSIONS: This study suggests that RTX is effective in patients with clinically active demyelinating anti-MAG neuropathy over 2 years of follow-up, and that some neurophysiological variables might be useful for monitoring this efficacy.

IgA vasculitis with underlying monoclonal IgA gammopathy: innovative therapeutic approach targeting plasma cells. A case series.

OBJECTIVE: There is currently no evidence of the possible benefit of plasma cell-targeting therapies (PCTT) in immunoglobulin A (IgA) monoclonal gammopathy (MG) associated with IgA vasculitis (IgAV). We report the outcome of different PCTT regimens in a cohort of MG-IgAV. METHODS: We used a French network to retrospectively describe the outcome of MG-IgAV patients treated with PCTT. RESULTS: Five patients were included (mean age 65 years). All patients had severe baseline presentation including extensive necrotic purpura (n = 5), gastrointestinal involvement (n = 2), peripheral neuropathies (n = 2), and glomerulonephritis (n = 1). Two patients had IgA indolent multiple myeloma and three had IgA "MG of undetermined significance." Monotypic IgA deposition in the skin vessels wall was highlighted using an immunofluorescence assay. Cases of vasculitis in three patients (n = 3) were refractory to multiple line therapies, including cyclophosphamide (n = 3) or rituximab. Finally, PCTT including bortezomib plus cyclophosphamide and dexamethasone, bortezomib plus melphalan and prednisone, or bortezomib plus lenalidomide and dexamethasone were proposed, allowing complete remission in 4/5 patients without major adverse drug events. CONCLUSION: This study suggests that the MG-IgAV phenotype might be distinctive of usual IgAV (severe and refractory to conventional immunosuppressive regimens) and supports the benefit of PCTT. This study sheds new light on the overall biology of IgAV, strengthening the pathogenic role of the monoclonal IgA component in IgAV.

How do we manage t(11;14) plasma cell disorders with venetoclax?

The oral BCL-2 inhibitor venetoclax has demonstrated promising efficacy in patients with t(11;14) plasma cell disorders, both as a single-agent and in combination. However, there was an increased mortality signal in the randomized BELLINI trial that was primarily driven by non-t(11;14) patients. Based on current evidence, venetoclax is included as an option for relapsed/refractory t(11;14) plasma cell dyscrasias in NCCN guidelines and is being widely used in clinical practice. In this review, we aim to critically appraise the current literature and perform case-based illustration of our approach to management of t(11;14) plasma cell disorders with venetoclax.

Long-Term Complete Clinical and Hematological Response With Bortezomib: The Report of a Case With TEM(P)I Syndrome and a Review of the Literature.

TEMPI syndrome was first defined in 2011 and classified as a plasma cell neoplasm with associated paraneoplastic syndrome in 2016. The pathogenesis of the syndrome is not well understood. Recognition of a combination of telangiectasia, erythrocytosis with a high erythropoietin level, monoclonal gammopathy, perinephric fluid collection, and intrapulmonary shunt is the first step in managing the disease. Diagnoses are often delayed because the syndrome is rare and can be mistaken for other dermatological, renal, and pulmonary disorders. Without early diagnosis significant disability results from the pulmonary damage. The article we present here describes a clinical case of TEMPI-syndrome in a 58-year-old woman, which illustrates the difficulties associated with the timely recognition of this unusual disease. Here, we also review the clinical features of TEMPI syndrome, differential diagnosis and available treatment options, based on current literature. Although limited in number, with the addition of new patients to the literature, TEMPI syndrome is evolving into a well characterized multisystem syndrome. This rare disorder should not be missed, especially if the patient has a putative diagnosis of essential telangiectasia with a monoclonal gammopathy and polistemia. Increasing the awareness of clinicians about the disease and adding new patient data to the literature may contribute to a better understanding of the pathophysiology of the disease and standardization of treatment.

Case report: Scleromyxedema associated with a monoclonal gammapathy: Successful treatment with intravenous immunoglobulins.

Scleromyxedema is a rare idiopathic fibromucinous disorder characterized by a generalized papular and sclerodermoid cutaneous eruption. Patients often have praraproteinemia and extracutaneous, even lethal, manifestations. Yet the prognostic and therapeutic features of scleromyxedema are poorly documented. High-dose intravenous immunoglobulin (IVIG), used either alone or in conjunction with systemic steroids and/or thalidomide, has been suggested as a first-line treatment. We report the case of a 45-year-old woman diagnosed with scleromyxedema with paraproteinemia that initially did not respond to systemic steroids, retinoids, and thalidomide but greatly improvement in terms of systemic and cutaneous symptoms after treatment with IVIG.

Prevalence and prognostic value of monoclonal gammopathy in heart failure patients with preserved ejection fraction: A prospective study.

BACKGROUND: Heart failure (HF) with preserved ejection fraction (HFpEF) and monoclonal gammopathy of uncertain significance (MGUS) are two entities that share pathophysiological mechanisms. The aim herein, was to assess the prevalence of MGUS in patients with HFpEF and no left ventricular (LV) hypertrophy, as well as its association with a pre-specified clinical endpoint at 12 months. METHODS: The present study prospectively enrolled 69 patients admitted with HF, with ejection fraction ≥ 50%, and LV wall thickness < 12 mm. All patients were screened for MGUS. Clinical events were determined over a 12 month follow-up. The pre-specified composite clinical endpoint was readmission for HF or death. RESULTS: The prevalence of MGUS in this population was 13%. There were no differences in the incidence of the composite clinical endpoint between patients with and without MGUS. Multivariate analysis showed that treatment with angiotensin converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) was associated with fewer clinical events (HR: 0.153, 95% CI: 0.037-0.622, p = 0.009) and indicated a trend to lower risk of readmission for HF and death. Beta-blockers were associated with lower rates of the composite clinical endpoint (HR: 0.192, 95% CI: 0.05-0.736, p = 0.016), readmission for HF (HR: 0.272, 95% CI: 0.087-0.851, p = 0.025) and indicated a trend to lower mortality. Moreover, potassium serum levels > 5 mEq/L were associated with higher rates of the composite endpoint (HR: 6.074, 95% CI: 1.6-22.65, p = 0.007). CONCLUSIONS: The prevalence of MGUS in patients with HFpEF without hypertrophy was 3-fold that of the general population. There was no significant correlation between clinical outcomes and the presence of MGUS. Beta-blockers and ACEIs/ARBs reduced the composite of mortality and readmissions for HF in HFpEF patients. Hyperpotassemia was related to worse prognosis.

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.

Update on therapy of chronic immune-mediated neuropathies.

Chronic immune-mediated neuropathies, including chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), neuropathies associated with monoclonal gammopathy, and multifocal motor neuropathy (MMN), are a group of disorders deemed to be caused by an immune response against peripheral nerve antigens. Several immune therapies have been reported to be variably effective in these neuropathies including steroids, plasma exchange, and high-dose intravenous (IVIg) or subcutaneous (SCIg) immunoglobulins. These therapies are however far from being invariably effective and may be associated with a number of side effects leading to the use of immunosuppressive agents whose efficacy has not been so far confirmed in randomized trials. More recently, new biological agents, such as rituximab, have proved to be effective in patients with neuropathy associated with IgM monoclonal gammopathy and are currently tested in CIDP.

Monoclonal gammopathy of renal significance: Early diagnosis is key / Gammapatía monoclonal de significado renal: la clave es el diagnóstico precoz

Monoclonal gammopathy of renal significance is a clinical–pathological entity grouping renal disorders secondary to the secretion of a monoclonal immunoglobulin synthesized by a B-cell-derived clone and/or plasma cells in a patient with no diagnostic criteria for multiple myeloma. This term applies to a concept recently introduced owing to the need to differentiate this entity from monoclonal gammopathy of undetermined significance, given the negative prognostic impact of its high morbidity and mortality resulting from both renal and systemic involvement, occasionally even progressing to advanced chronic kidney disease. The renal damage occurs via both direct pathogenic mechanisms, with the deposition of the monoclonal protein in different renal structures, as well as indirect mechanisms, acting as an autoantibody provoking dysregulation of the alternative complement pathway. The detection of this monoclonal protein and an early hematologic study are essential, as is the need for a kidney biopsy to establish the associated nephropathological diagnosis. Consequently, this then leads to the start of specific hematologic treatment to detain the production of the monoclonal protein and minimize renal and systemic injury. (AU)

La gammapatía monoclonal de significado renal es una entidad clínico-patológica que agrupa los trastornos renales secundarios a la secreción de una inmunoglobulina monoclonal sintetizada por un clon derivado de células B y/o células plasmáticas en un paciente sin criterios de diagnóstico de mieloma múltiple. Este término se aplica a un concepto introducido recientemente debido a la necesidad de diferenciar esta entidad de la gammapatía monoclonal de significado incierto, teniendo en cuenta el impacto pronóstico negativo de su alta morbilidad y mortalidad a causa de la afectación tanto renal como sistémica, llegando en ocasiones a progresar a una enfermedad renal crónica avanzada. El daño renal se produce tanto por mecanismos patogénicos directos, con el depósito de la proteína monoclonal en diferentes estructuras renales, como por mecanismos indirectos, actuando como un autoanticuerpo que provoca la desregulación de la vía alternativa del complemento. La detección de esta proteína monoclonal y un estudio hematológico precoz son imprescindibles, así como la necesidad de una biopsia renal para establecer el diagnóstico nefropatológico asociado. En consecuencia, esto lleva al inicio de un tratamiento hematológico específico para detener la síntesis de la proteína monoclonal y minimizar la lesión renal y sistémica. (AU)