Citations

Abstract BACKGROUND Electrophoretic separation of serum and urine proteins has played a central role in diagnosing and monitoring plasma cell disorders. Despite limitations in resolution and analytical sensitivity, plus the necessity for adjunct methods, protein gel electrophoresis and immunofixation electrophoresis (IFE) remain front-line tests. METHODS We developed a MALDI mass spectrometry–based assay that was simple to perform, automatable, analytically sensitive, and applicable to analyzing the wide variety of monoclonal proteins (M-proteins) encountered clinically. This assay, called MASS-FIX, used the unique molecular mass signatures of the different Ig isotypes in combination with nanobody immunoenrichment to generate information-rich mass spectra from which M-proteins could be identified, isotyped, and quantified. The performance of MASS-FIX was compared to current gel-based electrophoresis assays. RESULTS MASS-FIX detected all M-proteins that were detectable by urine or serum protein electrophoresis. In serial dilution studies, MASS-FIX was more analytically sensitive than IFE. For patient samples, MASS-FIX provided the same primary isotype information for 98% of serum M-proteins (n = 152) and 95% of urine M-proteins (n = 55). MASS-FIX accurately quantified M-protein to <1 g/dL, with reduced bias as compared to protein electrophoresis. Intraassay and interassay CVs were <20% across all samples having M-protein concentrations >0.045 g/dL, with the ability to detect M-proteins <0.01 g/dL. In addition, MASS-FIX could simultaneously measure κ:λ light chain ratios for IgG, IgA, and IgM. Retrospective serial monitoring of patients with myeloma posttreatment demonstrated that MASS-FIX provided equivalent quantitative information to either protein electrophoresis or the Hevylite™ assay. CONCLUSIONS MASS-FIX can advance how plasma cell disorders are screened, diagnosed, and monitored.

Abstract BACKGROUND Current recommendations for screening for monoclonal gammopathies include serum protein electrophoresis (PEL), imunofixation electrophoresis (IFE), and free light chain (FLC) ratios to identify or rule out an M-protein. The aim of this study was to examine the feasibility of an assay based on immunoenrichment and MALDI-TOF-MS (MASS-SCREEN) to qualitatively screen for M-proteins. METHODS Serum from 556 patients previously screened for M-proteins by PEL and IFE were immunopurified using a κ/λ-specific nanobody bead mixture. Following purification, light chains (LC) were released from their heavy chains by reduction. MALDI-TOF analysis was performed and the mass-to-charge LC distributions were visually examined for the presence of an M-protein by both unblinded and blinded analysts. RESULTS In unblinded analysis, MASS-SCREEN detected 100% of the PEL-positive samples with an analytical sensitivity and specificity of 96% and 81% using IFE positivity as the standard. In a blinded analysis using 6 different laboratory personnel, consensus was reached in 92% of the samples. Overall analytical sensitivity and specificity were reduced to 92% and 80%, respectively. FLC ratios were found to be abnormal in 28% of MASS-SCREEN–negative samples, suggesting FLC measurements need to be considered in screening. CONCLUSIONS MASS-SCREEN could replace PEL in a panel that would include FLC measurements. Further studies and method development should be performed to validate the clinical sensitivity and specificity and to determine if this panel will suffice as a general screen for monoclonal proteins.

Multiple myeloma (MM) patient frailty has been delineated primarily by age and ECOG performance score (PS) and recently by the IMWG frailty score based on functional status [Activity of Daily Living (ADL) and Instrumental‐ADL scores], comorbidities [Charlson‐comorbidity‐index (CCI)] and age. It was hypothesized that N‐terminal natriuretic peptide type B (NT‐proBNP) might be both a more convenient measure of frailty and a predictor of overall survival (OS). Three‐hundred and fifty‐one consecutive symptomatic MM patients who were seen at Mayo Clinic within 30 days of diagnosis and who had blood stored were eligible. Data from the first visit was abstracted and used to calculate an ADL, CCI, and measure the NT‐proBNP level. The best cutoff of NT‐proBNP predicting OS was 300 ng/L. Variables predictive for OS were ECOG‐PS, age, CCI, ADL, ISS, revised‐ISS, and NT‐proBNP. On multivariate analysis age ≥70, PS ≥2, and NT‐proBNP ≥300 were independent predictors of survival. Patients were assigned a score of 1 for each of these variables, creating stages I–IV with scores of 0–3 points, respectively. The median OS from diagnosis was not reached, 58, 28, and 18 months (P < 0.0001), respectively. This frailty risk schema was independent of initial therapy and the revised‐ISS. NT‐proBNP is a useful predictor of survival independent of age and PS. It is a widely available biomarker that could be added to the panel of laboratory tests of newly diagnosed MM patients and serve as a simple and objective tool of determining frailty in clinical practice. Am. J. Hematol. 91:1129–1134, 2016. © 2016 Wiley Periodicals, Inc.

Recent reports suggest that deep hematologic responses to chemotherapy are associated with improved renal outcomes in monoclonal immunoglobulin deposition disease (MIDD). Here we describe the long term outcomes and identify prognostic factors after first line treatment of the largest reported series of patients with MIDD. Between March 1992 and December 2014, 88 patients with MIDD were seen at Mayo Clinic, MN. Renal responses were defined using criteria used for light chain amyloidosis (AL) or those used by the IMWG. Sixty‐one (69%) patients had a GFR < 30 mL/min/1.73 m2 and 16 (18%) were on renal replacement therapy at diagnosis. The interval between albuminuria or elevation in creatinine and MIDD diagnosis was 12 months suggesting a delay in diagnosis. Thirty‐seven patients (42%) had at least a hematologic CR/VGPR. Fifty‐three (60%) received an autologous stem cell transplant (ASCT) or proteasome inhibitor (PI)‐based treatments. Patients receiving ASCT or PI‐based therapies were more likely to achieve at least a hematologic CR/VGPR compared to those receiving other therapies: 66% vs 2%, p < 0.0001. Patients that achieved a hematologic CR were more likely to achieve a renal response (53% vs 24%, p = 0.001). Five year overall and renal survival for the entire cohort was 67% and 57%, respectively. In multivariate analyses, a baseline GFR < 20 mL/min/1.73 m2 and a renal response (using AL or IMWG criteria) were independently predictive of progression to dialysis. This study confirms that deep hematologic responses, best achieved with ASCT or PI‐based therapies, are a prerequisite to achieving renal responses. Am. J. Hematol. 91:1123–1128, 2016. © 2016 Wiley Periodicals, Inc.

Catheter Ablation for Atrial Arrhythmias in Patients With CABackgroundCardiac amyloidosis (CA) is associated with increased atrial arrhythmias risk. The efficacy/safety of catheter‐based ablation therapy in patients with CA has not been adequately assessed.Methods and ResultsAll diagnosed CA patients who underwent atrial arrhythmia ablation therapy from 1995 to 2015 were reviewed. Arrhythmia recurrence, NYHA symptoms, and mortality were recorded. A total of 26 patients with CA and atrial arrhythmias were included; there were 7 light‐chain (AL), 17 wild‐type transthyretin (ATTRwt), and 2 mutated transthyretin (ATTRm) amyloidosis patients in total. Of which 13 underwent atrial arrhythmia ablation (CA‐A) and 13 underwent AV nodal ablation (CA‐AVN). In the CA‐A group, there were: 3 with atrial fibrillation (AF); 6 with atrial flutter (AFL); 2 with AF/AFL; and 2 with atrial tachycardia (AT). One‐year and 3‐year recurrence‐free survival were 75% and 60%, respectively. NYHA symptom improvement 6 months postablation was observed in both CA‐A and CA‐AVN groups: 7/10 (70%) and 4/8 (50%), respectively. Eleven patients with CA died (8 in CA‐AVN group vs. 3 in CA‐A group).ConclusionsCatheter‐based ablation for patients with CA appears to provide important symptomatic relief. However, mortality from the underlying disease remains a significant issue for the amyloid light‐chain subtype.

There is no consensus on whether patients with immunoglobulin light chain amyloidosis (AL) should receive induction therapy prior to an autologous stem cell transplant (ASCT). This study investigated the relationships between baseline bone marrow plasmacytosis (BMPC), cardiac staging, and pre‐transplant induction in AL patients. All patients who received ASCT for AL within 12 months of diagnosis were included. Patient characteristics and outcomes were abstracted. Univariate and multivariate modeling was performed. Among 415 AL patients, 35% had induction prior to ASCT. Post‐ASCT hematologic CR plus VGPR rates were significantly higher in those with baseline BMPC ≤ 10% compared to BMPC >10% (58% versus 40%, P = 0.0013). Significant risk factors for lack of attainment of CR included attenuated dose melphalan conditioning, baseline BMPC > 10%, no induction, and male gender. The 5‐year OS for the entire group was 65%. On multivariate analysis, risk factors for inferior OS included no induction therapy, advanced AL amyloid staging, BMPC > 10%, attenuated conditioning melphalan dose, and male gender. Patients with Mayo 2012 stage I–II patients with BMPC ≤ 10%, who comprised 56% of the ASCT population fared exceedingly well regardless of whether or not they received induction therapy with a 5‐year OS of 81 to 83%. Induction therapy pre‐ASCT may improve outcomes among AL patients due to a rapid reduction of toxic light chains or alternatively by elimination of less fit patients by “testing” their ability to tolerate chemotherapy. Prospective studies will be required to sort out these and other questions. Am. J. Hematol. 91:984–988, 2016. © 2016 Wiley Periodicals, Inc.

Amyloidosis is characterized by extracellular deposition of misfolded proteins as insoluble fibrils. Most renal amyloidosis cases are Ig light chain, AA, or leukocyte chemotactic factor 2 amyloidosis, but rare hereditary forms can also involve the kidneys. Here, we describe the case of a 61-year-old woman who presented with nephrotic syndrome and renal impairment. Examination of the renal biopsy specimen revealed amyloidosis with predominant involvement of glomeruli and medullary interstitium. Proteomic analysis of Congo red–positive deposits detected large amounts of the Apo-CII protein. DNA sequencing of the APOC2 gene in the patient and one of her children detected a heterozygous c.206A→T transition, causing an E69V missense mutation. We also detected the mutant peptide in the proband’s renal amyloid deposits. Using proteomics, we identified seven additional elderly patients with Apo-CII–rich amyloid deposits, all of whom had kidney involvement and histologically exhibited nodular glomerular involvement. Although prior in vitro studies have shown that Apo-CII can form amyloid fibrils and that certain mutations in this protein promote amyloid fibrillogenesis, there are no reports of this type of amyloidosis in humans. We propose that this study reveals a new form of hereditary amyloidosis (AApoCII) that is derived from the Apo-CII protein and appears to manifest in the elderly and preferentially affect the kidneys.

BACKGROUNDAutologous stem cell transplantation (SCT) is a common management strategy for select patients with immunoglobulin light‐chain amyloidosis, but no trials have documented improved overall survival.METHODSEighty‐nine patients with biopsy‐proven immunoglobulin light‐chain amyloidosis were allowed to select treatment with melphalan plus dexamethasone (n = 34) or SCT (n = 55); all patients were transplant eligible. Treatment preference resulted in imbalanced study arms. Patients who selected SCT were younger, more frequently had an Eastern Cooperative Oncology Group performance status score less than 2, had lower‐stage amyloidosis, and had a lower incidence of cardiac amyloidosis.RESULTSPatients receiving melphalan plus dexamethasone had a 3‐year progression‐free survival rate of 29.1% and an overall survival rate of 58.8%. Patients undergoing SCT had a 3‐year progression‐free survival rate of 51.7% and an overall survival rate of 83.6%. An attempt to match patients between the 2 arms in terms of risk produced 24 matched triplet sets (2 SCT patients for each melphalan‐dexamethasone patient); there was no difference in hematologic response, but there was better survival after autologous SCT. A propensity score–matched analysis of the cohorts (melphalan plus dexamethasone vs SCT) showed an overall mortality hazard ratio of 2.56 (P < .01).CONCLUSIONSAlthough the study had limitations, similar hematologic responses and improved survival were observed after SCT versus melphalan plus dexamethasone. Cancer 2016;122:2197–205. © 2016 American Cancer Society.