Serum Free Light Chain Assay Research Articles

Audit of the Prevalence of Noncorrelation of Immunofixation with Protein Electrophoresis and Serum Free Light Chain Assays in Multiple Myeloma in a Tertiary Cancer Care Center.

Multiple myeloma (MM) is diagnosed and monitored by correlating panel of test results including serum Protein electrophoresis (SPE), Immunofixation electrophoresis (IFE), serum Free Light chain (sFLC) measurements. This audit is aimed to evaluate the prevalence of non-correlation and discrepancies amongst the three investigations (SPE/IFE/sFLC) for assessment of MM. 106 MM patients were reviewed over 16months in a tertiary cancer care center by the availability of 3 serum test results (SPE/IFE/sFLC). Patients were divided into 2 groups: group1, newly diagnosed MM patients who were yet to receive myeloma specific treatment (n = 48); and group2, already diagnosed MM patients on treatment and followup (n = 58). Treatment modalities included stem cell transplantation and standard chemotherapy regimens. Non-correlation between the three test results (IFE/SPE/sFLC) was observed (21% in group1 and 45% in group2). Three types of discrepancies were detected as follows: (a) IFE showing less number of restriction bands as compared to SPE (8.6% patients in group2); (b) SPE/IFE negative with an abnormal sFLC ratio (12.5% patients in group1 and 13.7% in group2); (c) SPE/IFE positive but normal sFLC ratio (8% in group1 and 22% in group2). To conclude, IFE may sometimes provide information that does not always correlate with either of the SPE or sFLC results due to different sensitivities, antigen-antibody interactions, or treatment. Hence, SPE plus sFLC may be more useful particularly for patients on follow-up while IFE plus sFLC may help screen the new patients. The judicious selection of the biochemical assays can effectively reduce the treatment cost in a developing country like India.

Optimization of workflow and screening panels for the detection of malignant monoclonal gammopathies.

Multiple myeloma (MM) is one of the hematologic malignancies with a greater delay in diagnosis. Laboratories receive numerous MM screening test requests without a specific suspicion, which entails a substantial workload and reduces the efficiency of laboratories. Objective: to increase the efficacy of MM screening protocols. The results of serum protein electrophoresis (SPEP), serum protein immunofixation electrophoresis (SIFE), urine protein immunofixation electrophoresis, and serum free light chain assays of 75 patients with MM, three with amyloidosis, and a patient with solitary plasmocytoma were collected. The frequency of a set of biochemical alterations in these patients was compared with that in controls (n=120). A validation of the screening algorithm was carried out in 261 consecutive patients with a clinical or analytical suspicion of MM. SPEP+SFLC or SIFE+SFLC (98% sensitivity) were the screening algorithms with the highest sensitivity. Prospectively, the SPEP+SFLC detected 27 of the 28 confirmed cases of MG and saved 15h of work. Alterations in five of the six parameters studied were more frequent in the study group, with a cumulative value of≥3 parameters altered (61.1 vs. 1.7%) (positive predictive value: 85%; negative predictive value: 94%). The SPEP+SFLC screening protocol demonstrated the highest sensitivity and was the least time-consuming protocol. In addition, this protocol improves diagnostic sensitivity and laboratory performance.

SUN-060 LATE PRESENTATION OF NEPHROTOXICITY DUE TO OXALIPLATIN

Oxaliplatin is a third-generation platinum derivative and considered less nephrotoxic than Cisplatin. It is frequently used as part of chemotherapy to treat various gastrointestinal tumors. Although hypokalemia, ATN and acute nephrotoxicity in the form of renal tubular acidosis due to Oxaliplatin has been reported; long term nephrotoxic effects of Oxaliplatin are not known. We report a novel case of 57- year old male who presented with muscle aches and electrolyte disturbances, several months after receiving oxaliplatin based chemotherapy. Patient had a premorbid history of diabetes mellitus, hypertension and he was diagnosed to have intrahepatic cholangiocarcinoma with neuroendocrine differentiation in September 2018. His creatinine was normal 74 umol/L at baseline. He received five cycles of chemotherapy with FOLFIRINOX (Folinic acid, Flourouracil, Irinotecan and Oxaliplatin). After five cycles he developed Oxaliplatin related ileus and nephropathy causing ATN and required few sessions of hemodialysis. Subsequently his kidney function improved partially with a new elevated baseline creatinine which was stable at 133 umol/L in February 2019. He presented on 28th September 2019 with severe muscle aches to emergency department (ED). His investigations done in ED revealed severe hypokalemia K 1.9 mmol/L, worsening of renal function, baseline creatinine had risen from 133 umol/L to 205 umol/L, he had severe metabolic acidosis with tCO 2 10, with normal anion gap 15 (range 7-16) and hyperchloremia 111 mmol/L, pH was 7.15. His serum phosphorus was low (0.63 mmol/L). Magnesium was normal. Urinary TTKG was calculated and was suggestive of urinary potassium loss. His Urinary Anion Gap was negative. He had glycosuria 4 + even though his blood sugars were well controlled. His urine pH was 5.5. Patient was treated with very high doses of potassium tricitrate and phosphorus supplements. He was discharged home after normalization of electrolytes and acid base status. Proximal renal tubular acidosis (type 2, pRTA) / Fanconi’s syndrome is characterized by bicarbonate wasting and low serum bicarbonate, proximal tubular dysfunction also leads to poor absorption of other substances, like glucose and phosphate. Further investigations were carried out to rule out other causes of Fanconi’s syndrome / Type 2 renal tubular acidosis in this patient. ANA, dsDNA, SPEP, IFE and serum Free light chain assay were all unremarkable. His Lactate was normal. A diagnosis of Fanconi’s syndrome and renal tubular acidosis type 2 (Proximal) due to remote exposure with Oxaliplatin was made. Fanconi’s syndrome due to platinum based drugs like Cisplatin and Oxaliplatin has been reported in Literature. Persistence of subtle partial renal tubular defects is well noted even after many months to years of exposure of Cisplatin but not with Oxaliplatin. We believe this is the first report of Type 2 pRTA and Fanconi’s syndrome presenting several months after exposure to Oxaliplatin. Physicians should be aware of unexpected late nephrotoxicity with Oxaliplatin use.

Comparison of 2 Serum-Free Light-Chain Assays in CKD Patients

IntroductionQuantification of serum-free light chains (FLCs) is important in the diagnosis and monitoring of paraprotein-related diseases. There are currently 2 FLC assays available: the Freelite assay (Binding Site) and the N Latex assay (Siemens). There is emerging evidence that these assays give different results, but it is not established how kidney dysfunction affects these assays differently.MethodsIn this study, we measured and compared serum FLCs in patients with mild-to-moderate chronic kidney disease (CKD) using both assays.ResultsAlthough κ FLCs are higher by Freelite, λ FLCs are higher by N Latex. Both κ and λ FLCs correlate inversely with estimated glomerular filtration rate (eGFR) in the 2 assays, but this effect is more pronounced in λ-free light-chain measurement by N Latex. Consequently, although the κ/λ ratio by Freelite is inversely correlated by eGFR, the κ/λ ratio by N Latex is positively correlated with eGFR.ConclusionOur results clearly demonstrate that the 2 available FLC assays cannot be used interchangeably in patients with CKD.

In-house age-specific reference ranges for free light chains measured on the SPAPlus® analyser

Background The measurement of monoclonal free light chains is being increasingly utilized since the introduction of serum-based assays. It is important for laboratories to determine their own reference ranges in order to reflect the local population. The aim of this study was to determine if age-adjusted reference ranges for serum free light chains would have implications for demand management of further laboratory investigations including immunofixation. Methods After certain exclusions, 4293 samples from individuals seen in primary care across Oxfordshire between 2014 and 2016 were identified for analysis of patient characteristics, serum free light chain results and estimated glomerular filtration rate. Results We found age to be an independent variable when considering serum free light chain concentrations, ratio and estimated glomerular filtration rate. The reference ranges derived from our data differ markedly from the original Binding Site ranges. When the age-specific ranges are retrospectively applied to our population, there is a 38% decrease in follow-up testing with no loss of specificity. Conclusion We feel confident implementing new age-specific serum free light chain reference ranges in our laboratory. We have developed a simple algorithm for evaluating serum free light chains based on age and estimated glomerular filtration rate. We encourage laboratories to establish their own local reference ranges using large cohorts and their chosen serum free light chain assay platform.

Comparison of three different serum-free light-chain assays\u2014implications on diagnostic and therapeutic monitoring of multiple myeloma

The measurement of serum-free light chains (FLC) is standard of care in the diagnosis and management of multiple myeloma (MM). The revised international myeloma working group (IMWG) implemented the involved FLC/noninvolved FLC (iFLC/niFLC) ratio as a biomarker for MM requiring treatment. Recently, a new definition of high-risk smoldering MM (SMM) including iFLC/niFLC ratio was published. These recommendations were solely based on a single assay method (Freelite assay). Today, two additional assays, N Latex FLC and ELISA-based Sebia FLC, are available. Here, we report on a single-center-study comparing results of all three different assays for FLC correlation and its potential implications for diagnostic and clinical use. In total, 187 samples from 47 MM patients were examined, and determination of FLC was performed. Comparison analyses showed similar FLC results for Sebia FLC and N Latex FLC assay with markedly lower absolute values for κ/λ ratio compared with Freelite. Values of λ FLC exhibited high variability. The ratio of iFLC/niFLC showed significant discrepancies among these assays. Our data demonstrate that the three available assays may result in markedly discrepant results, and should not be used interchangeably to monitor patients. Furthermore, modifications of the assay-specific diagnostic (iFLC/niFLC) thresholds for SMM and MM are recommended.

Myeloma Cast Nephropathy Manifesting only as Unexplained Acute Renal Failure

Multiple Myeloma (MM) is characterised by clonal B cell proliferation affecting elderly age group and involving various organ systems namely haematological, renal and skeletal system. Kidney may be affected in 50% of cases of MM. Though, Chronic Kidney Disease (CKD) is usually seen in MM, unusual presentations have been documented. The present case is of a 50-year-old female with complains of breathlessness and vague generalised symptoms. Routine tests showed blood urea level of 90 mg/dL and serum creatinine of 8.3 mg/dL. Further investigations revealed 24 hour protein level 48.5 gm/day, Erythrocyte Sedimentation Rate (ESR)-126 mm/1st hour, cast nephropathy in renal biopsy. Immunohistochemical (IHC) study on renal biopsy revealed kappa light chain deposits in tubules, raised kappa light chains (3280.00 mg/L) in serum Free Light Chain (FLC) assay and MM in bone marrow aspiration and biopsy study. So, MM should be considered in differential diagnosis in elderly patients presenting with acute severe renal failure.

Detection and prevalence of monoclonal gammopathy of undetermined significance: a study utilizing mass spectrometry-based monoclonal immunoglobulin rapid accurate mass measurement

High-sensitivity mass spectrometry assays are available to detect monoclonal immunoglobulins. To better assess the prevalence of monoclonal gammopathy of undetermined significance (MGUS), we identified 300 patients diagnosed with MGUS or related gammopathy who had a prior negative work-up for monoclonal proteins as part of the Olmsted County MGUS screening study. Two mass spectrometry-based detection methods (matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and monoclonal immunoglobulin rapid accurate mass measurements (miRAMM) along with traditional immunofixation were performed on the Olmsted baseline and MGUS diagnostics serum samples. Among the 226 patients considered negative for MGUS based on protein electrophoresis and serum-free light-chain assay, a monoclonal protein could be detected at baseline in 24 patients (10.6%) by immunofixation, 113 patients (50%) by MADLI-TOF mass spectrometry, and 149 patients (65.9%) by miRAMM mass spectrometry. In addition, using miRAMM, some patients demonstrated an oligoclonal to monoclonal transition giving insight into the origin of MGUS. Using the sensitive miRAMM, MGUS is present in 887 of 17,367 persons from the Olmsted County cohort, translating into a prevalence of 5.1% among persons 50 years of age and older. This represents the most accurate prevalence estimate of MGUS thus far.

Serum Free Light Chain Assay As an Additional Tool for Defining Response and Progressive Disease in Immunoglobulin Secretory Multiple Myeloma

Serum Free Light Chain Assay As an Additional Tool for Defining Response and Progressive Disease in Immunoglobulin Secretory Multiple Myeloma

The Use of Next Generation Gene Sequencing to Measure Minimal Residual Disease in Patients with AL Amyloidosis and Low Plasma Cell Burden: A Feasibility Study

Background: AL amyloidosis is a bone marrow disorder in which clonal plasma cells produce light chains that misfold and deposit in vital organs, such as the kidneys and heart, leading to organ failure and eventual death. Treatment is directed towards the clonal plasma cell population in an effort to halt the production of toxic light chains and recuperate organ function. Pallidini et al. demonstrated that almost 50% of patients with AL amyloidosis who achieved a complete hematologic response to prior therapy had minimal residual disease (MRD) detectable in their bone marrow by multiparametric flow cytometry (MPF).1. Next generation gene sequencing (NGS) has been a successful tool in measuring MRD among patients with multiple myeloma2 though the data regarding its use in AL amyloidosis are limited. AL amyloidosis is a disease with a much smaller plasma cell burden at baseline (typically 5-10%), making the task of isolating an initial clonal sequence even more challenging. We sought to evaluate NGS as a method of isolating a clonal population of plasma cells among patients with systemic AL amyloidosis in a first-ever feasibility study. Methods: Patients were eligible if they had systemic AL amyloidosis and no clinical evidence of concurrent active multiple myeloma. In this study, feasibility was deemed successful if discovery of a clone could be achieved in 3 out of 10 of patients. Approximately five cc's of peripheral blood and bone marrow aspirate were collected from each patient and processed for CD138 selection and DNA isolation/purification. De-identified samples were sent to Adaptive Biotech Inc. (Seattle, WA) for initial clonal identification using the ClonoSEQ immunoglobulin heavy chain (IGH) assay. Genomic DNA was amplified by implementing consensus primers targeting the IGH complete (IGH-VDJH) locus, IGH incomplete (IGH-DJH) locus, immunoglobulin κ locus (IGK) and immunoglobulin l locus (IGL). The amplified product was sequenced and a clone identified based on frequency. After proof of feasibility in the first 10 patients an additional 27 patients had initial clonal identification via the same process mentioned above. Results: In total, 37 patient samples underwent NGS via the ClonoSEQ IGH assay method. The median patient age was 66 years old (range: 44 to 83), 24% of which were female. All 37 patients had measurable disease based on serum electrophoresis and immunofixation and/or serum free light chain assay (Table 1). Four patients had no monoclonal protein detected on SIFE or UIFE and 13 patients had a normal sFLC ratio. Of the 33 patients with monoclonal disease on immunofixation, 12 patients had only a free lambda monoclonal protein and the remaining 21 patients had a clonal heavy chain with an associated light chain. Bone marrow biopsies demonstrated clonal plasmacytosis of 40% or lower. ClonoSEQ IGH assay identified trackable clones in 31 of 37 patients (84%) (see Table 1). Four patients had at least one trackable sequence (range: 1 to 5 sequences) in the peripheral blood and 29 patients had at least one trackable sequence in the bone marrow aspirate (range: 1 to 7 sequences). No correlation was seen between the detection of a clone and standard measures of plasma cell tumor burden (SIFE, SPEP, UIFE, UPEP, and sFLCs). Conclusion: NGS was successful in identifying an initial clone in 29 of 37 patients with systemic AL amyloidosis, four of which were detectable in the peripheral blood. Due to the low clonal burden in patients with AL amyloidosis, it is often difficult to assess disease status, especially post-treatment. These encouraging results may enhance disease monitoring and improve patient care in this rare disease. We are currently tracking MRD in the patients with identifiable clones as they receive systemic treatment, the results of which will be available for presentation in December 2019. REFERENCES 1. Palladini G, Massa M, Basset M, Russo F, Milani P, Foli A, et al. Persistence of Minimal Residual Disease By Multiparameter Flow Cytometry Can Hinder Recovery of Organ Damage in Patients with AL Amyloidosis Otherwise in Complete Response. Abstr 3261. 2016; 2. Ladetto M, Brüggemann M, Monitillo L, Ferrero S, Pepin F, Drandi D, et al. Next-generation sequencing and real-time quantitative PCR for minimal residual disease detection in B-cell disorders. Leukemia. 2014;28:1299-307. Table 1 Disclosures Sarosiek: Acrotech: Research Funding. Sanchorawala:Proclara: Consultancy, Honoraria; Takeda: Research Funding; Caelum: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Research Funding; Prothena: Research Funding; Celgene: Research Funding. Jacob:Adaptive Biotechnologies: Employment, Other: shareholder. Munshi:Amgen: Consultancy; Adaptive: Consultancy; Celgene: Consultancy; Celgene: Consultancy; Janssen: Consultancy; Janssen: Consultancy; Takeda: Consultancy; Takeda: Consultancy; Oncopep: Consultancy; Oncopep: Consultancy; Amgen: Consultancy; Abbvie: Consultancy; Abbvie: Consultancy; Adaptive: Consultancy.

Nonsecretory Mutiple Myeloma. A Rare Hemathologic Entity and Possible Misdiagnosis. A Case Report Warning

Nonsecretory multiple myeloma (NSMM) is a rare subtype of mutiple myeloma (MM). MM is normally associated with the secretion of monoclonal Ig (M spike) detected by serum or urine immunofixation/ electrphoresis; however in NSMM an M spike is not dedected, thus leading to either a misdiagnosis or a delayed diagnosis. A recent method of assessment for plasma cell disorders, serum free light chain assay (SFLC), individuates cases with measurable amounts of FLC, i.e., oligosecretory multiple mieloma (OSMM) or FLC-MMs.

Detection and Prevalence of Monoclonal Gammopathy of Undetermined Significance: A study utilizing mass spectrometry-based monoclonal immunoglobulin rapid accurate mass measurement

High-sensitivity mass spectrometry assays are available to detect monoclonal immunoglobulins. To better assess the prevalence of monoclonal gammopathy of undetermined significance (MGUS), we identified 300 patients diagnosed with MGUS or related gammopathy who had a prior negative work-up for monoclonal proteins as part of the Olmsted County MGUS screening study. Two mass spectrometry-based detection methods (matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) and monoclonal immunoglobulin rapid accurate mass measurements (miRAMM) along with traditional immunofixation were performed on the Olmsted baseline and MGUS diagnostics serum samples. Among the 226 patients considered negative for MGUS based on protein electrophoresis and serum-free light-chain assay, a monoclonal protein could be detected at baseline in 24 patients (10.6%) by immunofixation, 113 patients (50%) by MADLI-TOF mass spectrometry, and 149 patients (65.9%) by miRAMM mass spectrometry. In addition, using miRAMM, some patients demonstrated an oligoclonal to monoclonal transition giving insight into the origin of MGUS. Using the sensitive miRAMM, MGUS is present in 887 of 17,367 persons from the Olmsted County cohort, translating into a prevalence of 5.1% among persons 50 years of age and older. This represents the most accurate prevalence estimate of MGUS thus far.

Laboratory testing in the evaluation of a monoclonal protein: A practical framework for interpretation

Monoclonal proteins are immunoglobulins secreted by identical but abnormal plasma cells that are clones of a parent cell. While routine screening in the absence of signs or symptoms of disease is not recommended, testing is indicated in the diagnostic work-up for multiple myeloma and other plasma cell disorders. When indicated, a serum protein electrophoresis with immunofixation and serum free light-chain assay should be performed to determine the type and quantity of monoclonal protein. Using a case-based approach, we highlight common misconceptions with monoclonal protein investigations, and suggest a practical framework for diagnostic interpretation.

Comparison of Serum Free Light Chain Assay and Urine Protein Electrophoresis for the Detection of Monoclonal Gammopathies

Abstract Laboratory detection of monoclonal immunoglobulins is essential for the diagnosis and monitoring of monoclonal gammopathies (MGs). In alignment with the recent effort from the College of American Pathologists (CAP) to develop evidence-based clinical practice guideline for laboratory detection and initial diagnosis of MGs, we retrospectively collected 1-year laboratory results from three tests, including serum protein electrophoresis (SPEP) with reflex to immunofixation (IFE), urine protein electrophoresis (UPEP) with reflex to immunofixation (IFE), and serum free light chain analysis (FLC), to identify the current ordering patterns from clinical care providers and analyze the diagnostic performances of these tests. From February 2018 to February 2019, there were a total of 5,614 SEPEs ordered with 19% reflexed for IFE. Among these, 70% were reported negative for SPEP without reflexing to IFE and 5% were reported negative after confirmation by IFE, with the rest being positive for monoclonal immunoglobulin(s) confirmed by either current or previous IFE results. Together with SPEP, FLC was ordered more often than UPEP (36% vs 19% of the total SPEP orders), with 12% of these having all three tests ordered. Using serum immunofixation results as a reference, we compared the diagnostic performance of UPEP and FLC as initial screening tools, with FLC considered abnormal if abnormal kappa/lambda ratio was accompanied with at least one elevated free light chain concentration. FLC had slightly higher sensitivity compared to UPEP (63% vs 56%) but with lower positive predictive value (69% vs 82%). When combining FLC with UPEP, the sensitivity increased to 79% with a positive predictive value of 71%. Interestingly, FLC and UPEP also showed various sensitivity in detecting specific type of free light chains, with FLC being positive in 81% of UPEP with detectable free kappa light chain, but only positive in 62% of UPEP with detectable free lambda light chain. Due to the reflex algorithm nature, those specimens with negative SPEP were not reflexed for IFE and therefore could not be used to assess the performance of FLC and UPEP. In summary, FLC was more frequently ordered than UPEP in addition to SPEP by our clinicians, although the majority of SPEPs were still ordered alone. In our practice, FLC and UPEP had comparable performance, with FLC showing slightly higher sensitivity but lower specificity. The current data did not support the replacement of one with the other, given that there was only 50% overlapping on positive identifications between FLC and UPEP. Further studies to include serum IFE for all specimens and clinical correlations would be beneficial to fully assess the diagnostic performance of FLC and UPEP, as well as their utilizations for various patient populations and clinical purpose.

Real-world epidemiology, treatment patterns and survival of multiple myeloma patients in a large nationwide health plan

BackgroundSurvival of patients with multiple myeloma (MM) has improved significantly with access to autologous stem cell transplant (SCT) and new treatments. This study aims to describe epidemiology, treatment patterns, and outcomes of MM in Israel. MethodsA retrospective observational study was conducted in Maccabi Healthcare Services, a 2-million-member nationwide health plan in Israel. MM was defined by cross-linking data on MM diagnoses, dispensed treatments, and serum free light-chain assays. Point prevalence (31/12/2016) and incidence (2012–2016) rates were age-standardized. Newly diagnosed and treated patients (2009–2015) were followed through 31/12/2016 for progression to second-line (L2), with death as a competing risk. ResultsMM prevalence and incidence rates were 26.2 and 4.6 per 100,000 population, respectively. In the treatment cohort (N = 552), mean ± SD) age was 65.6 ± 11.3) years (60.1% male) and median (95% CI) OS in years was 5.2 (4.3–6.1) overall and 6.5 (4.9–8.1) for first-line (L1) bortezomib (N = 421). In a multivariable analysis, OS was significantly higher among patients starting L1 in 2012–2015 vs. 2009–2011. Within a year, 38.4% underwent SCT. Cumulative incidence of L2 was 38.2% and 51.4% within 1 and 2 years, respectively, and was associated with older age (≥65y; P < 0.001). ConclusionThese results from a large heterogeneous population demonstrate MM incidence and survival rates that are in line with the literature, together with a significant improvement in overall survival over time. Approximately half of newly treated patients progressed to L2 within two years. These results will serve as a baseline for further research to evaluate the clinical impact of new interventions.

PB2108 CIRCULATING PLASMA CELLS: AN APPROACH BASED ON NEXT GENERATION FLOW TOOLS IN MONOCLONAL GAMMAPATHIES

Background:Peripheral blood (PB) is an accessible tissue to study the traffic of all types and subsets of cells. The frequency of PB involvement depends on the sensitivity of the methods used. Next Generation Flow (NGF)‐MM MRD Euroflow workflow provides a high specific, sensitive and applicable method to detect plasma cells in multiple myeloma (MM) patients after therapy. This Standard Operation Procedure (SOP) can be used to increase the sensibility of circulating plasma cells detection. Taking this into account, we investigated the frequency and number of circulating tumor plasma cells in PB of newly diagnosed patients with localized and systemic plasma cell neoplasms (PCN) using NGF.Aims:to detect, identificate and quantificate both compartments, pathologycal and normal circulating plasma cells in patients with monoclonal gammapathies.MethodsOverall, 26 samples ‐13 bone marrow (BM) and 13 paired PB samples‐ from 13 adult patients (5 males and 8 females; median age of 72 years, ranging from 42 to 85 years) with newly diagnosed PCN, were studied. In parallel, 5 PB samples from healthy donors with ages and sex similar as the patients were also investigated. Patients were classified according to the International Myeloma Working Group (IMWG) criteria into: 6 monoclonal gammopathy of undetermined significance (MGUS), 2 smoldering multiple myeloma (SMM), 5 MM patients. PB (range: 5.2 mL–10.7 mL) samples were processed following EuroFlow Bulk Lysis Standard Operating Protocols and stained with EuroFlow‐MM MRD panel 2‐tube/8‐color. A range of 5.9 × 106‐12.7 × 106 events were measured in PB samples using a FACSCanto II (BD Biosciences, San Jose, USA) flow cytometer. Information acquired were analyzed using Infinicyt software 2.0 (Cytognos, Salamanca, España). Serum Free Light Chains Assay (Binding Site) in SPAPLus platform.Results:In all newly diagnosed PCN patient and healthy donor, circulating normal plasma cells were detected in PB (0,00103% &gt; 0.3818%; 0,060 PC/uL‐1,510 PC/uL). Circulating tumoral plasma cells were detected in PB of all MM (100%) and SMM (100%) patients studied. Meanwhile, in only one case of the total of MGUS patients CTPC were identified. Free light‐chains (FLC) ratio, pathologycal/normal, in MGUS ranged between 1.1 to 3.2 and in the MM cases were &gt; 370. Circulating tumoral plasma cells showed an immunophenotype profile similar to their partner in BM. Even though, our number of patients was very low (total = 13) we found lower fluorescense intensity level in specifics markers such as: CD138, CD38 and CD56 in circulating tumoral plasma cells respect to BM.Summary/Conclusion:The EuroFlow NGF‐MM MRD panel and workflow show high sensitivity to detect CPC in PB of every newly diagnosed MM and SMM patient. Nevertheless, the majority of MGUS cases showed no detectable CTPC in PB, but these findings are correlated with a low FLC ratio, suggesting that these MGUS cases can be associated with a lower risk of malignant progression.

Serum Free Light-chain Assay for the Diagnosis, Management, and Prognosis of Multiple Myeloma

Serum Free Light-chain Assay for the Diagnosis, Management, and Prognosis of Multiple Myeloma

Method comparison of the new Sebia serum free light chain assay, against the Binding Site Freelite assay

Method comparison of the new Sebia serum free light chain assay, against the Binding Site Freelite assay

Serum Free Light Chain Assay in Monoclonal Gammopathic Manifestations.

Serum free light chain assay is used in the diagnosis and monitoring of monoclonal gammopathic manifestations. For the kappa (κ)/lambda (λ) ratio, there is a 36% false-positive rate in patients without monoclonal gammopathic manifestations and a 30% false-negative rate in patients with monoclonal gammopathic manifestations. This study was undertaken to address the higher false-negative rate in λ chain-associated monoclonal lesions. Results of serum protein electrophoresis, serum immunofixation electrophoresis, and serum free light chain assays were reviewed retrospectively. The results for serum free light chains in cases of intact immunoglobulin monoclonal gammopathic manifestations only were analyzed. Concentrations of involved serum free light chains were significantly higher in κ chain-associated lesions than in λ chain-associated lesions. The concentration of uninvolved light chains was significantly higher in λ chain-associated lesions. κ light chains are present in significantly greater abundance than are λ chains in their respective monoclonal lesions. Moreover, κ and λ light-chain levels are not comparable for similar quantitative levels of monoclonal immunoglobulins. The findings warrant a reconsideration of the role of serum free light chain concentrations and involved to uninvolved serum free light chain ratio in designation of myeloma-defining conditions and other diagnostic criteria based on serum free light chain assay.

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.