Serum Free Light Chain Levels Research Articles

Serum free light chains levels in patients with monoclonal gammopathy

Serum free light chains levels in patients with monoclonal gammopathy

EFFECT OF CHRONIC FUROSEMIDE THERAPY ON SERUM FREE LIGHT CHAIN IN CHRONIC KIDNEY DISEASE PATIENTS

Objective: Chronic kidney disease (CKD) is an important cause of morbidity and mortality worldwide. There is a lack of information on the epidemiology and progression of CKD in low-middle-income countries. Chronic use of diuretics is considered to further decrease renal clearance, a pathophysiology not very clearly understood. Free light chains renal deposition is precipitated by loop diuretics. This study attempted to determine whether chronic diuretic usage was associated with increase serum free light chain and a reduction in renal clearance among CKD patients. Design and method: A single-center, record-based study of 84 CKD patients with an established diagnosis of CKD, loop diuretic therapy, between June 2019 and December 2019 was conducted after ethical approval by institutional ethics committee ((RIMS/2018/32). The study included participants with age above 18 years of age, never dialysed, non-neoplastic (specifically plasma cell disorder), non-pregnant, and those on loop diuretic were divided into 3 groups: group 1 with Furosemide exposure more than 6 months; Group 2 with furosemide exposure between 3 months to 6 months but less than 6 months; and Group 3 with furosemide exposure less than 3 months. Results: 46 out of 84 patients were of group 1, 20 belonged to group 2 and 18 were in group 3. In group 1, mean eGFR of 103.6, mean free kappa of 100.98 and mean lambda of 126.65.2 was observed. Group 2 patients had mean eGFR of 125.6 with mean free kappa of 80.98 and mean lambda of 1002.2, whereas group 3 had mean eGFR of 15 5.5, mean free kappa of 79.8 and mean lambda of 96.65.2. It was also observed that 98% patients with stage 5 CKD had high serum free lambda level. Conclusions: This study revealed a strong association of serum free light chain level with stage of CKD in patients on diuretic therapy. Therefore, monitoring of Serum Free Light Chain among CKD patients on diuretic therapy can be an indirect evidence of furosemide induced renal function worsening.

The correlation between serum free light chain levels and plasma cell ratio in bone marrow biopsy in multiple myeloma

Aims: MM (Multiple myeloma) is the second most common hematological malignancy. In addition to the recent advances in treatment, new parameters are used in clinical practice in diagnosis and follow-up. sFLC (free chain kappa and lambda) shows the activation of the disease depending on the rate of MM malignant cell secretion in serum. However, the plasma cell (PC) ratio in bone marrow biopsy is still the gold standard in diagnosis. We examined the dynamic correlation between the PC ratio and the number of sFLC-related cells and the secretion rate. We aimed to examine whether a low PC ratio could be in a more aggressive form with a higher sFLC secretion with too much activity, thus examining the correlation between them.
 Methods: A total of 62 newly diagnosed MM patients admitted to Başkent University Faculty of Medicine İstanbul Hospital were included in the study. At the time of diagnosis, sFLC values were requested simultaneously with bone marrow biopsy. Radiological images were obtained with PET CT/MRI or CT.
 Results: In all MM groups, bone marrow PH percentages were not correlated with sFLC regardless of subtype. IgG kappa type MM had the highest sFLC values despite the lowest number of PHs, while Lambda light chain MM had the lowest sFLC despite the highest PH rates. 
 Conclusion: These results showed us that sFLC rates are independent of the percentage of PC in MM. We believe that the two are not correlated and should be followed up together in the follow-up of the disease.

Serum Neurofilament and Free Light Chain Levels in Patients Undergoing Treatment for Chronic Inflammatory Demyelinating Polyneuropathy.

Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an immune-mediated disorder affecting the peripheral nervous system. Despite the established diagnostic criteria, monitoring disease activity and treatment remains challenging. To address this limitation, we investigated serum neurofilament light chain (sNfL) and serum free light chains (sFLCs) as potential biomarkers. A total of 32 CIDP patients undergoing immunoglobulin therapy and 32 healthy controls enrolled in the present study, and agreed to have their blood plasma sNfL and sFLCs analyzed, while CIDP severity was assessed through the modified Rankin Scale (mRS) and the Overall Neuropathy Limitations Scale (ONLS). In line with the immunoglobulin treatment aimed at limiting neuronal damage administered to the majority of patients, sNfL levels did not exhibit significant differences between the two groups. However, CIDP patients showed significantly elevated sFLC and sFLC ratios, while the marker levels did not correlate with the clinical scores. The study confirms the potential of sFLCs as a sensitive biomarker of inflammatory processes in CIDP. Additionally, the present study results regarding neurofilaments strengthen the role of sNfL in monitoring CIDP treatments, confirming the effectiveness of immunoglobulin therapy. Overall, our results demonstrate how combining these markers can lead to better patient characterization for improved treatment.

Association of Serum Free Light Chain Level with Long-Term Kidney Function in Patients with Newly Diagnosed Multiple Myeloma

Introduction: Multiple myeloma (MM) frequently involves the kidneys, resulting in acute, subacute, or chronic kidney disease (CKD). Patient- and treatment-related factors are associated with the long-term development of CKD. The aim of our study was to examine the association of serum free light chain (FLC) levels, measured at the time of diagnosis of MM, and CKD at subsequent follow-up. Methods: Patients with newly diagnosed MM were identified using cancer registries at five hospitals. The primary outcome was low eGFR (<60 mL/min/1.73 m2) or dialysis dependence and a secondary composite outcome of low eGFR, dialysis dependence, or death at the last follow-up, up to 12 months from diagnosis. Logistic regression analyses were performed. Results: A total of 149 patients met the inclusion criteria. Patients with an FLC level above the median had a higher frequency of hypertension (54% vs. 81%; p < 0.001), hyperlipidemia (37% vs. 56%; p = 0.018), low eGFR at the time of diagnosis (43% vs. 66%; p = 0.006), and a higher MM stage (p = 0.018). On multivariable analyses, after adjustment for several covariates, serum FLC level (per each 100 mg/L) was independently associated with low eGFR or dialysis dependence at follow-up (adjusted odds ratio [aOR] 1.021; 95% CI: 1.002, 1.041; p = 0.033). This association persisted for the composite outcome of low eGFR, dialysis dependence, or death (aOR 1.034; 95% CI: 1.006, 1.063; p = 0.018). Discussion/Conclusion: Higher serum FLC level measured at the time of MM diagnosis is independently associated with CKD at up to 12 months of follow-up.

Lambda-free light chain: A serum marker of dengue disease via NS3 protease-mediated antibody cleavage

ABSTRACT Dengue poses a significant global public health threat, with diverse clinical manifestations due to complex interactions between the host and the pathogen. Recent reports have highlighted elevated serum-free light chain (FLC) levels in viral infectious diseases. Hence, our study aimed to investigate serum FLC levels in dengue patients. The findings revealed elevated serum λ FLCs, which were associated with the severity of dengue. Receiver operating characteristic curve (ROC) analysis demonstrated that λ FLCs may serve as a serum marker for identifying dengue disease (AUC: 0.7825, sensitivity: 80, specificity: 71.43) and classifying severe dengue (AUC: 0.8102, sensitivity: 75, specificity: 79.52). The viral protease, Dengue virus (DENV) nonstructural protein 3 (NS3), acts as a protease that cleaves viral polyproteins as well as host substrates. Therefore, we proposed that antibodies might be potential targets of NS3 protease, leading to an increase in FLCs. LC/MS-MS analysis confirmed that λ FLCs were the predominant products after antibody degradation by NS3 protease. Additionally, purified NS3 protease cleaved both human IgG and DENV2-neutralizing antibodies, resulting in the presence of λ FLCs. Moreover, NS3 protease administration in vitro led to a reduction in the neutralizing efficacy of DENV2-neutralizing antibodies. In summary, the elevated serum λ FLC levels effectively differentiate dengue patients from healthy individuals and identify severe dengue. Furthermore, the elevation of serum λ FLCs is, at least in part, mediated through NS3 protease-mediated antibody cleavage. These findings provide new insights for developing diagnostic tools and understanding the pathogenesis of DENV infection.

P-092 High serum free light chains levels in African ancestry population screened for monoclonal gammopathy: implication for definition of FLC reference range accounting for renal function and race

P-092 High serum free light chains levels in African ancestry population screened for monoclonal gammopathy: implication for definition of FLC reference range accounting for renal function and race

#5130 THE EXPERIENCE OF SELECTIVE PLASMA EXCHANGE THERAPY IN PATIENTS WITH MULTIPLE MYELOMA

Abstract Background and Aims High concentrations of free light chains (FLCs) in multiple myeloma lead to cast-nephropathy and obstructive acute renal failure in 18-56% of patients. The aim of this research is to estimate the efficiency of extracorporeal free light chains of immunoglobulin elimination under this pathological condition during plasma exchange therapy using selective filters. Method Selective plasma exchange therapy (SEPET) was carried out in 11 patients with multiple myeloma. The patients were 61 [47-69] years old. Paraproteinemia level at primary examination varied from 1.6 to 78.8 g/liter. All patients exhibited proteinuria of 0.56 to 12.7 g/day, Bence Jones protein excretion (from 0.4 to 11.2 g/day) was detected in 9 cases. Blood creatinine levels ranged from 272 μmol/L to 534 μmol/L. None of the patients required renal replacement therapy. FLCs levels above 500 mg/L, irrespective of azotemia level, served as an indication for starting the procedure. All patients received VMP induction chemotherapy after sessions of selective plasma exchange therapy. SEPET was carried out on a “Multifiltrate” (Fresenius) hemodialysis machine in hemofiltration mode. «Evaclio 2C20» plasmafilter (Japan) was used. Patients underwent one procedures of SEPET in a dose of 3 volumes of circulating plasma. Blood flow velocity during varied from 40 to 60 ml/min, the duration of each procedure was 5-6 hours. Plasma substitution was performed with «Prismasol K4» solution - 10.0 L and albumin solution 20%-400 ml. Regulated clotting by nonfractionated heparin was calculated individually from the APTT values. No early or delayed complications of extracorporeal hemocorrection were recorded. FLCs, creatinine levels, and coagulogram results of patients were examined before and after the procedure. Results Analysis of serum FLC values before treatment showed a significant increase of κ- or λ-FLC levels, significantly surpassing normal values: 3-21.5 mg/liter κ-FLC and 5-27 mg/liter λ-FLC, with κ/λ-FLC proportion of 0.25-1.65. The primary levels of involved FLC medians in the group were 472 [312;44700] mg/L for κ-FLC and 163 [ 473; 24673] mg/L for λ-FLC, κ/λ-FLC proportions were 2.89. Through the membrane of the plasma filter “Evaclio 2C20” are sieved and removed substances with a molecular weight less than the molecular weight of albumin (65 kD). Kappa FLCs circulate as monomers of 22 kDa but may assemble into dimers of 45 kDa, particularly lambda FLCs. There is a partial loss of albumin. High molecular weight substances do not pass through this membrane. During SEPET the κ-FLC level in the plasmafiltrate was 272 mg/L, the λ-FLC level was 94 mg/L. After SEPET median serum κ-FLC was 231 mg/L, median serum λ-FLC was 96 mg/L. Compared with baseline data, serum FLC levels decreased after 24 hours, so that median serum κ-FLC was 281 mg/L, median serum λ-FLC was 101 mg/L. Clinical tolerance of extracorporeal detoxification was satisfactory and hemodynamically stable in all patients; and there were no were traumas of blood elements or decrease of serum albumin. Renal function recovered in 3 patients in the course of therapy, improved in 5 patients with renal insufficiency, and remained unchanged in 3 patients. Conclusion The Selective plasma exchange therapy directly removes FLCs excess from circulating blood. Rapid reduction of FLCs level in the course of selective extracorporeal elimination can prevent the development of irreversible renal failure and make it possible to carry out adequate antitumor therapy.

Belantamab mafodotin (belamaf) for relapsed/refractory multiple myeloma (RRMM): A real-world observational study update.

e20046 Background: A prior retrospective analysis of US patients (pts) with RRMM suggested that pts treated with belamaf, a BCMA-targeting antibody-drug conjugate, experienced similar outcomes to those who received belamaf in the pivotal DREAMM-2 study. This updated analysis aimed to characterize pts, assess occurrence and management of ocular adverse events (AEs), and evaluate belamaf effectiveness in a real-world setting. Methods: This retrospective, longitudinal, observational study used data sourced from the US EHR-derived Flatiron Health de-identified database (01/01/2011–06/30/2022). Eligible pts had a confirmed MM diagnosis, initiated belamaf after FDA approval (08/05/2020; first administration=index date), were ≥18 years old at index, and had chart abstraction data for ocular safety and treatment effectiveness. Data on ocular AEs were reported separately for all pts and pts with ≥4 months (mo) of follow-up to allow for sufficient follow-up to evaluate incidence of ocular AEs and their mitigations. Tumor response was assessed in all pts, along with Kaplan-Meier estimates of duration of response (DoR), overall survival (OS), and progression-free survival (PFS). Results: Of the 184 pts included in the study, mean age was 68.7 years; 64% were White and 47% were female. Eastern Cooperative Oncology Group (ECOG) status was ≥2 in 28% patients, 62% had received ≥5 prior lines of therapy, and 82% were triple-class refractory. Median (IQR) follow-up was 4.1 (1.9–8.5) mo. Among pts with ≥4 months of follow-up (n=94) 75% had ≥1 ocular AE, with keratopathy and blurred vision being the most frequent. Mean (SD) time to first ocular AE was 39 (34) days. Most ocular AEs were managed by therapy hold (69%; of which 73% restarted belamaf) and/or AE treatment (63%). The median dose hold due to ocular AEs was 43 days (physician-reported keratopathy: mild, 21 days; moderate/severe, 56 days). In all pts, 39 (21%) had a derived tumor response based on serum free light chain levels, (partial response: 74%, very good partial response: 51%). For all pts, the estimated median DoR was 9.1 mo, PFS 4.5 mo, and OS 7.9 mo, while the 6-month DoR rate was 57%, PFS rate was 46%, and OS rate was 58%. Conclusions: Overall, belamaf was effective in the real world setting in heavily pre-treated pts with RRMM and limited therapy options. The AE profile was consistent with DREAMM-2. Ocular AEs were manageable and despite their occurrence, a high percentage of pts remained on treatment, suggesting belamaf may fill an unmet need for triple-class refractory pts with RRMM. [Table: see text]

Pattern of serum immunoglobulins and free light chain levels among patients diagnosed with multiple myeloma in Southeast Nigeria

Pattern of serum immunoglobulins and free light chain levels among patients diagnosed with multiple myeloma in Southeast Nigeria

Evidence Supporting Light Chain Cast Nephropathy As a Myeloma Defining Event

BACKGROUND In 2014, the International Myeloma Working Group (IMWG) revised the Renal involvement of the CRAB (hyperCalcemia, Renal, Anemia, Bone lesions) criteria for the diagnosis of multiple myeloma (MM) as an acute decline in kidney function represented by either a serum creatinine (Scr) > 2 mg/dl or an estimated glomerular filtration rate of < 40 ml/min/1.73 m2 secondary to light chain cast nephropathy (LCCN) biopsy proven or suspected. Since LCCN occurs only in patients with high serum free light chain (FLC) levels, a high tumor burden is presumed but how often it occurs with other myeloma defining events (MDE) is unknown. METHODS Patients were selected from 2 cohorts. The first cohort came from a multicenter study on LCCN who were all diagnosed with MM between 2000 and 2018. Only newly diagnosed patients were included in this study. A second cohort was identified from the Mayo Clinic Kidney Biopsy database from 2003 to 2013. Inclusion criteria of this cohort were: the LCCN must be the dominate pathology on the kidney biopsy and it is secondary to a plasma cell proliferative disorder. Laboratory and radiologic data were collected to assess for CRAB criteria. Bone lesions were assessed by standard skeletal X-ray, MRI or CT/PET. Most had skeletal X-ray. The new SLiM CRAB criteria which have the addition 3 biomarkers: (S) >60% bone marrow plasma cells, (Li) an involved to uninvolved free light chain (FLC) ratio > 100 and (M) >1 bone lesion on MRI were also assessed. RESULTS From the multicenter study, 28 patients were excluded for having relapsed MM and 27 were from Mayo who were included in the second cohort leaving 123 patients. In the Mayo cohort, 52 patients were identified who met criteria. Both cohorts were comparable in age, sex, bone marrow plasma cells and hemoglobin at diagnosis (Table 1). Interestingly, 3.3% of the multicenter cohort and 3.9% of the Mayo cohort did not meet the R criterion due to a presenting creatinine of ≤ 2.0 mg/dl. In the multicenter cohort 2/99 (2.0%) and 4/52 (7.7%) of the Mayo cohort had < 10% bone marrow plasma cells. The presenting involved FLC was higher in the multicenter group (p = 0.001). In the multicenter cohort, 99.1% met at least one of the SLiM criteria and 84.7% met one the C,A,B criteria. In the Mayo cohort, fewer patients met at least one of the SLiM criteria (86.5%, p < 0.001) but more patients met one or more of the C,A,B criteria (98.1%, p = 0.01). All but 1 patient from the multicenter cohort met one or more of the SliM C,A,B criteria. The most common SLiM criteria met in the multicenter cohort was Li while it was M in the Mayo cohort. The most common C,A,B criteria in the multicenter cohort was A while it was B in the Mayo cohort. DISCUSSION This study provides the first evidence that nearly all patients who present with biopsy proven LCCN have at least one other MDE. Bone marrow burden was met in 98.0% of the multicenter cohort where all patients were diagnosed with MM, 92.3% of the Mayo cohort where the diagnosis of MM was not a prerequisite. More importantly, 84.7% and 98.1% of patients from the 2 cohorts respectively had another MDE besides LCCN confirming that LCCN is associated with high tumor burden. All but 1 patient would have been diagnosed with MM based on the SLiM CRAB criteria. In comparison to patients with other kidney lesions associated with monoclonal immunoglobulin, generally only 20-30% met the CRAB criteria for MM. This is why it is more appropriate to classify those patients as having monoclonal gammopathy of renal significance while patients with LCCN should be diagnosed with MM. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Management of Atrial Fibrillation Using Immunoglobulin Free Light Chains, Novel Biomarkers of Inflammation.

AF is the most common cardiac arrhythmia. There is growing evidence that inflammatory mechanisms play an important role in its pathogenesis; inflammasome activation contributes to the onset and progression of AF. An increase in NOD-like-receptor-pyrin domain-containing-3 (NLRP3) inflammasome activation releases proinflammatory cytokines that activate nuclear factor (NF)-κB, which regulates the production of immunoglobulin free light chains (FLCs). Serum FLC levels are increased in patients with AF, and FLCs are biomarkers of inflammation. Inflammasomes and NF-κB may be targets for anti-inflammatory strategies to prevent and treat AF when FLC levels are elevated. This review discusses the role of inflammation in the pathogenesis of AF, as well as FLCs as novel inflammatory biomarkers for the management of AF.

69-Year-Old Man With Dysuria and Right Lower Abdominal Pain

69-Year-Old Man With Dysuria and Right Lower Abdominal Pain

Serum Free Light Chain Assay as a Prognostic Marker in Patients with Aggressive B-Cell Non-Hodgkin's Lymphoma: Impact on Survival Outcome.

T.M. AnoopBackground The role of serum free light chain (FLC) as a prognostic biomarker in lymphoproliferative diseases is being increasingly studied. In this study we present the 5-year survival outcome for patients with aggressive B-cell non-Hodgkin's lymphoma (NHL) and their relation to FLC and other known prognostic markers. Materials and Methods This is a prospective study conducted in patients diagnosed with aggressive B-cell NHL. Serum FLC level and ratio were estimated prior to initiation of treatment. Results A total of 100 patients were included in the study from December 2013 to December 2015 with a median age of 53 years. Thirty-eight patients (38%) had elevated FLC level of which 26% were polyclonal and 12% were monoclonal elevations. Abnormal FLC ratio was noted in 12% patients. Median follow-up duration of the study was 75 months. Five-year relapse-free survival (RFS) for the study population was 54.4%. Five-year RFS was 64.1% for early stage and 48.2% for advanced stage diseases ( p = 0.05). The RFS was significantly better in age less than 60 years (59.5% vs 43.8%, p < 0.001). Five-year overall survival (OS) was 61.3%. OS was significantly better in younger patients (73.6% vs 33.4%, p < 0.001), with International Prognosis Index score of 0 to 2 (87.4% vs 26.7%, p < 0.001). Patients with elevated FLC had inferior RFS (50% vs 71.4%, p = 0.04). Abnormal FLC ratio also strongly corresponded to inferior RFS (54.5% vs 66.2%, p = 0.001). OS was also significantly inferior in patients with abnormal FLC ratio (72.6% vs 63.6%, p = 0.001). Conclusion In patients with newly diagnosed aggressive B-cell NHL, elevated FLC levels and abnormal FLC ratio were significantly associated with inferior survival.

The role of serum free light chain as biomarker of Myasthenia Gravis

Background and aimMyasthenia gravis (MG) is a B lymphocyte–mediated disease affecting neuromuscular transmission. The clinical course of MG is unpredictable due to the fluctuating nature and heterogeneity of the disease. Increased levels of free light chains (FLC), which reflect B cell activation, have been detected in different autoimmune disorders. In this study, we evaluated the potential role of FLC as diagnostic and prognostic biomarkers of MG. Materials and methods74 MG patients and 52 healthy individuals were included in the study. Serum FLC levels were measured by turbidimetric assay (Freelite, The Binding Site Group Ltd) on the Optilite Analyser System in both groups. In MG patients, anti-AChR and anti-MuSK autoantibodies were detected by enzyme-linked immunosorbent assay. ResultsMG patients displayed significantly higher serum κ and total FLC levels than controls, respectively for κFLC 16.0 vs 13.8 mg/L and for total FLC 29.8 vs 25.9 mg/L. Moreover, increased κFLC levels were observed in seropositive MG patients. No association was observed between serum FLC levels and clinical manifestations of disease as well as with severity, age at MG onset, thymoma and treatment. ConclusionIncreased levels of κFLC and total FLC could serve as biomarkers to support the diagnosis of MG.

Myocardial Composition in Light-Chain Cardiac Amyloidosis More Than 1 Year After Successful Therapy

ObjectivesThe goals of this study were to characterize myocardial composition during the active and remission phases of light-chain (AL) cardiac amyloidosis. BackgroundCardiac dysfunction in AL amyloidosis is characterized by dual insults to the myocardium from infiltration and toxicity from light chains during the active phase and by infiltration alone in the remission phase. MethodsProspectively enrolled subjects with cardiac AL amyloidosis (21 remission AL amyloidosis; age: 63.4 ± 7.3 years; 47.6% male; and 48 active AL amyloidosis; age: 62.5 ± 7.4 years; 60.4% male) underwent contrast-enhanced cardiac magnetic resonance with T1 and T2 mapping and measurement of extracellular volume (ECV). By definition, serum free light-chain levels were normal for at least 1 year following successful AL therapy in the remission group and abnormal in the active group. ResultsMyocardial ECV was similarly expanded in the remission and active AL amyloidosis groups (0.488 ± 0.082 vs 0.519 ± 0.083, respectively; P = 0.15). However, myocardial T2 relaxation times (47.7 ± 3.2 ms vs 45.5 ± 3.0 ms; P = 0.008) as well as native T1 times (1,368 ms [IQR: 1,290-1,422 ms] vs 1,264 ms [IQR: 1,203-1,380 ms]; P = 0.024) were significantly higher in the remission compared to the active AL amyloidosis group. ConclusionsMyocardial ECV is substantially expanded in the active AL and remission AL cardiac amyloidosis groups, but native T1 values were higher, suggesting a different myocardial composition. There is no evidence of myocardial edema in active AL cardiac amyloidosis. Future phenotyping studies of AL cardiac amyloidosis need to consider complementary myocardial markers that define the interstitial milieu in addition to changes in extracellular volume. (Molecular Imaging of Primary Amyloid Cardiomyopathy; NCT02641145)

RNA-based immunoglobulin repertoire sequencing is a new tool for the management of monoclonal gammopathy of renal (kidney) significance

The diagnostic approach of monoclonal gammopathy of renalsignificance is based on the detection of a monoclonal immunoglobulin in the blood and urine, and the identification of the underlying clone through bone marrow and/or peripheral blood cytologic and flow cytometry analysis. However, the monoclonal component and its corresponding clone may be undetectable using these routine techniques. Since clone identification is the cornerstone for guiding therapy and assessing disease response, more sensitive methods are required. We recently developed a high-throughput sequencing assay from bone marrow mRNA encoding immunoglobulins (RACE-RepSeq). This technique provides both full-length V(D)J region (variable, diversity andjoining genes that generate unique receptors as antigen receptors) of the monoclonal immunoglobulin and the dominant immunoglobulin repertoire. This allows analysis ofmutational patterns, immunoglobulin variable gene frequencies and diversity due to somatic hypermutation. Here, we evaluated the diagnostic performance of RACE-RepSeq in 16 patients with monoclonal-associated kidney lesions, and low serum monoclonal immunoglobulin and free light chain levels at diagnosis. Bone marrow immunohistochemical analysis was negative in all 11 patients so tested and 7 of 12 patients had no detectable clone matching the kidney deposits using flow cytometry analysis. By contrast, RACE-RepSeq detected a dominant clonal light chain sequence of matched isotype with respect to kidney deposits in all patients. Thus, high throughput mRNA sequencing appears highly sensitive to detect subtle clonal disorders in monoclonal gammopathy of renal significance and suggest this novel approach could help improve the management of this kidney disease.

Defining New Reference Intervals for Serum Free Light Chains in Individuals with Reduced Kidney Function: Results of the Population- Based on Iceland Screens Treats or Prevents Multiple Myeloma (iStopMM) Study

Background: In addition to serum protein electrophoresis (SPEP) and serum immunofixation (IFE), measurement of serum free light chains (FLC) has become the hallmark for detection, prognostication, and monitoring of monoclonal gammopathies. However, serum FLC levels are heavily dependent on kidney function due to discrepancy in the rate of kidney clearance of the FLC. As chronic kidney disease (CKD) is common in the general population, it is possible that a large number of individuals have false FLC results. A kidney reference interval (eGFR < 60) has previously been published based on small numers (N=688) for serum FLC ratio (0.37-3.10) instead of the standard reference interval (0.26-1.65), but no kidney reference exists for kappa (3.3-19.4mg/L) or lambda (5.7-26.3mg/L). The aim of this study was to define and improve the reference interval for individuals with various degree of decreased kidney function and assess its effect on prevalence of light chain monoclonal gammopathy of undetermined significance (LC-MGUS) among CKD patients.Methods: A total of 80,759 participants of the Iceland Screens, Treats or Prevents Multiple Myeloma (iStopMM) study were included. Participants were screened by SPEP and IFE as well as by serum FLC assay (Freelite®). Serum creatinine (SCr) value closest to the time of screening was used to calculate (CKD-EPI) eGFR. Participants with M-protein, eGFR >60 mL/min/1.73 m2, missing SCr measurements or more than 1 year from the SCr measurement to the iStopMM screening were excluded. Correlation was assessed graphically and using the Spearman correlation coefficient. A nonparametric bootstrapping method was used to calculate the 95% CI. Partitioning was determined based on the proportion of subgroups (sex, age, eGFR) outside the whole group reference interval (<0.9% or >4.1%). However, intervals were not partitioned if subgroups included few participants and/or if deemed more applicable and reasonable for clinical practice. LC-MGUS was defined as FLC ratio outside the reference interval and raised FLC level without evidence of monoclonal heavy chain on SPEP or IFE or end-organ damage attributed to the plasma cell proliferative disorder.Results: Of 75,422 individuals who were screened, 6,503 (12%) participants had eGFR < 60 mL/min/1.73 m2, without evidence of monoclonality on SPEP or IFE and were analysed further. The median (IQR) kappa level was 21.7 (16.6-29.4) mg/L, lambda level 19.0 mg/L (14.8-25.0) and FLC ratio 1.16 (0.97-1.39). Serum FLC levels increased with decreasing eGFR: serum free kappa (ρ= -0.44, p < 0.001), lambda (ρ= -0.39, p < 0.001), and FLC ratio (ρ= -0.15, p < 0.001). Using current reference intervals, 60% and 21% of persons had values outside the normal range for kappa and lambda, respectively. The FLC ratio was outside the standard reference interval in 9% and outside the kidney reference interval in 0.6% of participants. Based on these findings, we established new reference intervals for FLC and FLC ratio (Table). Participants on dialysis (N=26) had significantly higher median (IQR) serum free kappa 29.3 mg/L (26.1-57.6, p = 0.01) and lambda 25.1 mg/L (19.5-52.6, p = 0.01) than participants with eGFR 30-59, but no significant difference compared to participants with eGFR < 30 (p = 0.57). The FLC ratio in participants on dialysis was 1.22 (0.96-1.37), which was similar to participants with eGFR 45-59 (p = 0.63) and 30-44 (p = 0.34). Participants on dialysis had significantly lower FLC ratio than participants with eGFR < 30, or 1.31 (1.10-1.57, p = 0.02). Utilising our novel reference intervals, the crude prevalence of LC-MGUS in all participants with eGFR < 60 was 75 (1.2%), with no difference between participants with eGFR of 45-59, 30-44 and < 30, respectively. When the crude rate of LC-MGUS was compared to a rate based on previous reference intervals, the crude rate of both kappa and lambda LC-MGUS increased in participants with eGFR 45-59, eGFR 30-44 and eGFR < 30 (p<0.001).Conclusion: Current reference intervals for serum FLC and FLC ratio are inaccurate for patients with decreased kidney function. Here we propose new reference intervals for serum FLC and FLC ratio for use in patients with CKD which also seem to be accurate in patients on dialysis. Implementing these novel reference intervals is likely to increase the sensitivity and specificity of the analyses and lead to a more accurate diagnosis of monoclonal gammopathy in individuals with kidney dysfunction. [Display omitted] DisclosuresKampanis: The Binding Site: Current Employment. Hultcrantz: Intellisphere LLC: Consultancy; Curio Science LLC: Consultancy; GlaxoSmithKline: Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Research Funding; Daiichi Sankyo: Research Funding. Durie: Amgen, Celgene/Bristol-Myers Squibb, Janssen, and Takeda: Consultancy; Amgen: Other: fees from non-CME/CE services . Harding: The Binding Site: Current Employment, Membership on an entity's Board of Directors or advisory committees, Patents & Royalties. Landgren: Janssen: Research Funding; Amgen: Honoraria; Janssen: Honoraria; Celgene: Research Funding; Janssen: Other: IDMC; Takeda: Other: IDMC; Amgen: Research Funding; GSK: Honoraria. Kristinsson: Amgen: Research Funding; Celgene: Research Funding.

Results from a Pilot Study of ARI0002h, an Academic BCMA-Directed CAR-T Cell Therapy with Fractionated Initial Infusion and Booster Dose in Patients with Relapsed and/or Refractory Multiple Myeloma

Results from a Pilot Study of ARI0002h, an Academic BCMA-Directed CAR-T Cell Therapy with Fractionated Initial Infusion and Booster Dose in Patients with Relapsed and/or Refractory Multiple Myeloma

Free Light-Chain Levels in Patients with Transthyretin Amyloid Cardiomyopathy in Attr-ACT

Introduction: In cardiac amyloidosis (CA), immunoglobulin-derived light chains (AL) and transthyretin (TTR) are the most common amyloidogenic proteins infiltrating the heart. 1 Identification of the specific precursor protein leading to amyloid deposition is needed to establish the correct therapeutic approach. 2 In both AL- and TTR-related CA, an early and accurate diagnosis is critical to achieving the best treatment outcomes. TTR amyloid cardiomyopathy (ATTR-CM) is often misdiagnosed as other causes of heart failure (HF), including AL CA. 3 While almost all patients with AL amyloidosis have elevated serum free light-chain (sFLC) levels and abnormal free kappa:lambda (κ:λ) ratios, 4 patients with ATTR-CM can also have abnormal sFLC levels due to either an unrelated monoclonal gammopathy or relative κ-predominance in renal dysfunction. 2,5 Because ATTR-CM most often occurs in elderly adults and is commonly accompanied by renal comorbidity, we theorized that patients with ATTR-CM may have κ:λ ratios that approach, or exceed, the upper limit of the normal reference range (0.26-1.65 6). High light-chain ratios in these patients have the potential to increase the likelihood of misdiagnosis of a monoclonal plasma cell disorder and may lead to unnecessary referrals to hematologists and/or inappropriate treatments. To explore this theory, we evaluated κ:λ ratios in patients with biopsy-proven ATTR-CM who were enrolled in the Tafamidis in Transthyretin Cardiomyopathy Clinical Trial (ATTR-ACT). 7Methods: In ATTR-ACT, a double-blind, placebo-controlled, randomized study, patients with biopsy-proven ATTR-CM, and without light-chain amyloidosis, received tafamidis or placebo for 30 months. In the current analysis, sFLC levels and κ:λ ratios were assessed in the intent-to-treat population (N=441), excluding patients with a prior diagnosis of monoclonal gammopathies (n=13; defined by MedDRA preferred terms: ‘monoclonal gammopathy’, ‘plasma cell myeloma’, ‘plasma cell disorder’, and ‘hypergammaglobulinemia benign monoclonal‘). Subgroup analyses were performed by estimated glomerular filtration rate (eGFR) category (≥60 vs ≥40 to <60 vs <40 mL/min/1.73 m 2). Findings were summarized using descriptive statistics (min/max, mean, median, and interquartile range [IQR]).Results: In 422 patients with ATTR-CM and available sFLC data, and without a prior diagnosis of monoclonal gammopathies, the mean κ:λ ratio was 1.45 (median, 1.20 [IQR, 0.98, 1.47]) (Figure). The ratio increased with declining renal function: eGFR ≥60 mL/min/1.73 m 2, mean, 1.25 (median [IQR], 1.11 [0.94, 1.38]); ≥40 to <60 mL/min/1.73 m 2, 1.52 (1.22 [0.99, 1.49]); and <40 mL/min/1.73 m 2, 1.62 (1.30 [1.05, 1.68)].Conclusions: In patients with biopsy-proven ATTR-CM without known monoclonal gammopathies who were enrolled in ATTR-ACT, the mean κ:λ ratio showed a κ-predominance, often exceeding the upper range of normal in patients with more advanced kidney dysfunction. The findings suggest that individuals with ATTR-CM can have higher sFLC levels than those normally seen in the general population, and such elevations do not necessarily indicate the presence of monoclonal gammopathy of undetermined significance or AL CA. In an era when most patients with ATTR-CM and without monoclonal gammopathies are diagnosed noninvasively using bone scintigraphy, age- and renal-function-based sFLC norms are critical to ensure appropriate use of diagnostic testing modalities.