Kappa Free Light Chains Levels Research Articles

Comparison of 2 Serum Free Light Chain Assays with Creatinine Normal and Abnormal Populations Demonstrates the Need for Standardization.

The objective of this study was to compare The Binding Site's Freelite on Optilite and Diazyme's Kappa/Lambda free light chains (K/L FLC) on Abbott Architect c8000 with healthy and renal insufficient populations and to evaluate their respective reference intervals for serum free light chains (sFLCs). Two hundred sixty serum samples were measured for creatinine and sFLCs by both assays and a subset by immunofixation electrophoresis. Verification of manufacturer-defined reference intervals was assessed. Kappa free light chains (KFLC) showed excellent correlation of 0.998 R2 with a slope of 0.73. For Lambda free light chains (LFLC), an acceptable correlation of 0.953 R2 was found with a slope of 1.50 as well as a skewness-based difference with a -12.70 intercept. Healthy estimated glomerular filtration rate (eGFR) ≥60 reference interval verification of central 95% could not be confirmed for either Freelite or Diazyme although LFLC was much closer than KFLC for both assays with Freelite KFLC recovering only 37% of values within reference interval claims. The K/L FLC ratio did not meet 100% claim for both Freelite (91%) and Diazyme (95%) among those with eGFR ≥60. Samples with eGFR ≤59 had increasingly higher levels of KFLC and LFLC for both assays. When comparing worsening eGFR status, Freelite recovered increasingly higher ratios while Diazyme recovered increasingly lower ratios. Healthy reference intervals could not be verified for either Freelite or Diazyme. Renal reference intervals for Freelite are currently warranted while they are not recommended for Diazyme. The differences between these 2 assays can be minimized by standardization efforts such as recalibration.

A rare case of IgE kappa monoclonal gammopathy of undetermined significance identified in a Swedish female

Monoclonal gammopathies involving immunoglobulin E (IgE) is a very rare phenomenon, with less than 70 cases being previously described in the literature. The IgE monoclonal gammopathies include malignant plasma cell disorders such as IgE multiple myeloma (MM), as well as the associated premalignant condition IgE monoclonal gammopathy of undetermined significance (MGUS). We report a case of a 41-year-old woman presenting with an IgE kappa monoclonal protein following routine laboratory testing. Serum protein electrophoresis (SPEP) initially showed a monoclonal protein in the beta-2 fraction, at an estimated concentration of <4 g/L. Subsequent serum immunofixation electrophoresis (SIFE) including antisera to Ig heavy chains delta and epsilon confirmed the presence of an IgE kappa monoclonal protein. Analysis of serum free light chains (FLCs) showed increased levels of kappa FLC, resulting in an abnormally elevated kappa/lambda FLC ratio. No Bence–Jones proteinuria was present. Bone marrow aspiration showed 6% plasma cells, and no sign of myeloma-associated end-organ damage was evident. Consequently, the patient was diagnosed with IgE kappa MGUS. In the present report, the clinical characteristics of the patient are compared to previous descriptions of IgE monoclonal gammopathy. The report further emphasizes the importance of considering the presence of monoclonal IgD or IgE when SIFE shows a clear band positive for a light chain but is negative for Ig heavy chains gamma, alpha and mu.

A Phase I Dose Escalation Study of PT-112 in Patients with Relapsed or Refractory Multiple Myeloma

Background: PT-112 is a novel pyrophosphate-platinum conjugate with a multi-modal mechanism of action that induces immunogenic cell death and is not susceptible to DNA-repair drug resistance pathways. In phase I studies in solid tumors, PT-112 demonstrated safety and efficacy as single agent and in combination with PD-L1 checkpoint inhibitor avelumab, crossing a range of dose levels (DL) and tumor types, including in heavily pre-treated patients (pts) non-responsive to immunotherapy and refractory to other modalities. Non-clinical, in vivo research using advanced imaging technology demonstrated that PT-112 reached the highest concentrations in bone tissue (osteotropism). Moreover, PT-112 was highly active in the orthotopic, immune-competent Vk*MYC mouse model of multiple myeloma, including drug-resistant transplant variants. Thus, a rationale for PT-112 as an investigational candidate in multiple myeloma was established. Here, we present results of a phase I dose escalation study of PT-112 in pts with relapsed or refractory multiple myeloma (RRMM). Methods: A 3+3 design was used to determine the recommended phase 2 dose (RP2D) for PT-112 (28-day cycle IV days 1, 8, 15) in pts with evaluable RRMM who had exhausted available therapies (Tx), with adequate bone marrow (abs neutrophil count ≥ 1.0 x 109/L; platelet count ≥ 50 x 109/L; and hemoglobin ≥ 8.0 g/dL) and renal function (calculated creatinine clearance ≥ 30 mL/min), and ECOG PS 0-2. Results: A total of 24 pts were treated with PT-112 monotherapy across 6 DLs: 125 mg/m2, 3 pts; 180 mg/m2, 4 pts; 250 mg/m2, 5 pts; 300 mg/m2, 4 pts; 360 mg/m2, 4 pts; 420 mg/m2, 4 pts. Patients had a median age of 72 years and were heavily pre-treated, with a median of 8 prior lines of systemic Tx: 22 (92%) pts were triple-class refractory with 19 (79%) pts penta-refractory, and 3 (13%) pts refractory to BCMA-based therapies. The most common treatment-related adverse events (TRAEs) were thrombocytopenia (58%), neutropenia (42%), diarrhea (38%), and nausea (38%). 38% of pts had ≥1 grade 3 non-hematologic TRAE, with no grade 4 non-hematologic TRAEs reported. One dose-limiting toxicity (DLT) of grade 4 neutropenia occurred at the 420 mg/m2 DL. In addition, due to frequent dose reductions and modifications at this DL, the safety committee declared 360 mg/m2 as the RP2D. Among 8 patients who received a starting dose at / above the RP2D, 2 had stable disease and 4 experienced responses to PT-112 Tx. These included a confirmed partial response (PR) achieved in a 79-year-old pt with kappa free light chain (FLC) disease treated at 360 mg/m2, whose previous Tx included combination regimens with most approved therapies (penta-refractory) and stem cell transplantation. FLC levels declined by 65% from baseline on PT-112 therapy and the pt remained progression free for 4.5 months. A 72-year-old pt treated at the 420 mg/m2 DL, reduced to 250mg/m2 every other week over the course of Tx due to grade 3-4 cytopenias, had a confirmed minor response. Prior Tx with multiple lines given over 9 years included stem cell transplantation, most approved therapies (penta-refractory), prior investigational antibody and CAR-T cell Tx (primary refractory to CAR-T). The patient was M-protein negative, kappa FLC levels declined by 32% following the first dose reduction, and the pt remained progression free and clinically stable without complaints for 4.5 months. Additionally, two transient, unconfirmed PRs occurred in patients at the 420mg/m2 DL: in a triple-class-refractory 82-year-old previously treated with 5 lines of Tx, with 70% reduction in kappa FLC during cycle 1; and in a penta-refractory 85-year-old, who experienced disappearance of M-protein during cycle 1 and Gr 4 neutropenia (DLT). Conclusions: PT-112 monotherapy was feasible and well tolerated in this heavily pre-treated, multi-refractory multiple myeloma population, and the Phase I clinical data appear to validate the developmental hypothesis, built upon activity in the Vk*MYC mouse model of multiple myeloma. Responses were confirmed in 25% of patients treated at / above the RP2D using single-agent PT-112, an encouraging result in a dose escalation trial conducted in heavily refractory patients. Activity of PT-112 in RRMM patients may be explained by its osteotropism and its unique mechanism of action compared to other drug classes used to treat this disease. Further clinical study of PT-112 in RRMM is warranted in a phase 2 clinical trial. Disclosures Ailawadhi: Celgene: Honoraria; Janssen: Research Funding; Pharmacyclics: Research Funding; Amgen: Research Funding; Medimmune: Research Funding; BMS: Research Funding; Cellectar: Research Funding; Phosplatin: Research Funding; Takeda: Honoraria. Vogl:Janssen: Consultancy; Celgene: Consultancy; MorphoSys: Consultancy; Takeda: Consultancy; Active Biotech: Consultancy, Research Funding; Oncopeptides: Consultancy; Karyopharm: Consultancy. Ames:Phosplatin Therapeutics: Current Employment, Current equity holder in private company. Yim:Phosplatin Therapeutics: Current Employment, Current equity holder in private company. Price:Phosplatin Therapeutics: Current Employment, Current equity holder in private company. Jimeno:Phosplatin Therapeutics: Current Employment, Current equity holder in private company.

Kappa Index Versus CSF Oligoclonal Bands in Predicting Multiple Sclerosis and Infectious/Inflammatory CNS Disorders.

Background: Cerebrospinal fluid (CSF) kappa free light chains (KFLC) are gaining increasing interest as markers of intrathecal immunoglobulin synthesis. The main aim of this study was to assess the diagnostic accuracy (AUC) of the kappa index (CSF/serum KFLC divided by the CSF/serum albumin ratio) compared to CSF oligoclonal IgG bands (OCB) in predicting Multiple Sclerosis (MS) or a central nervous system infectious/inflammatory disorder (CNSID). Methods: We enrolled patients who underwent a diagnostic spinal tap throughout two years. KFLC levels were determined using a Freelite assay (Binding Site) and the turbidimetric Optilite analyzer. Results: Of 540 included patients, 223 had a CNSID, and 84 had MS. The kappa index was more sensitive (0.89 versus 0.85) and less specific (0.84 versus 0.89), with the same AUC (0.87) as OCB for MS diagnosis (optimal cut-off: 6.2). Adding patients with a single CSF IgG band to the OCB-positive group slightly increased the AUC (0.88). Likewise, the kappa index (cut-off: 3.9) was more sensitive (0.67 versus 0.50) and less specific (0.81 versus 0.97), with the same AUC (0.74) as OCB, for a CNSID diagnosis. Conclusion: The kappa index and CSF OCB have comparable diagnostic accuracies for a MS or CNSID diagnosis and supply the clinician with useful, complementary information.

Cerebrospinal fluid kappa and lambda free light chains in oligoclonal band-negative patients with suspected multiple sclerosis.

Cerebrospinal fluid (CSF) kappa free light chains (FLCs) may be a more sensitive marker of intrathecal immunoglobulin (Ig)G synthesis compared with oligoclonal bands (OCBs). Our aim was to retrospectively determine the additional value of the kappa and lambda index (CSF FLC/serum FLC)/(CSF albumin/serum albumin) in predicting a multiple sclerosis (MS) diagnosis in a group of OCB-negative patients with suspected MS. The CSF and serum kappa and lambda FLCs were tested using the Freelite kit (serum) and Freelite Mx (CSF) assay (The Binding Site Group, Bimingham, UK) in 391 OCB-negative patients with suspected/possible MS and in 54 OCB-positive patients with MS. The CSF kappa FLC levels were below the detection limit (0.27 mg/L) in 61% of patients. Using quantitative data, we found the best kappa index cut-off value for the prediction of MS to be 5.8. A kappa index ≥5.8 was present in 25% of OCB-negative MS (23/92) and in 98% of OCB-positive patients with MS. Using a qualitative approach and a kappa index cut-off of 5.9, based on literature data, we likewise found that 24% of OCB-negative patients with MS had a kappa index ≥5.9, compared with 5.4% of OCB-negative patients without MS (P<0.001). No reliable data could be obtained for the lambda index; lambda FLCs were below the detection limit (0.68mg/L) in 90% of CSF samples. The kappa index could contribute to the identification of OCB-negative patients with a high probability of an MS diagnosis. Using more sensitive techniques might even improve the diagnostic performance of the kappa index and better define the role of the lambda index.

The effects of intrathecal rituximab on biomarkers in multiple sclerosis

ObjectivesClinical trials of IV-rituximab have proved successful. It is unclear whether intrathecal (IT)-rituximab is more efficacious at lower doses. We examine its effects on B-cell biomarkers. MethodsMS patients received IT-rituximab at 3 time-points. CSF and serum samples were obtained at up to 5 time-points (days 0, 7, 14, 56 and 112).Serum and CSF BAFF and CXCL13, and CSF kappa and lambda free light chains (FLC) were measured. Flow cytometry was performed, examining effects on lymphocytes, CD3-19+ and CD3-20+ cells. ResultsCSF BAFF fell following rituximab (p=0.0091 absolute values, p=0.0284 change from baseline) whilst serum BAFF increased across time-points 1–4 (p=0.0005 absolute values, p=0.0017 change from baseline).There were significant reductions in CD20+ and CD19+ cells in blood from baseline (p<0.0001) but not in CSF. CSF kappa FLC levels significantly increased (p=0.0480). ConclusionsBAFF levels fall in CSF but increase in serum following IT-rituximab. Rituximab appears to act peripherally with dramatic decreases in peripheral CD20+ and CD19+ cells. It is likely that CSF B-cell counts were too low to enable differences to be seen. The rapid reduction in B-cells suggests rituximab has immediate effects. The profound depletion of B-cells, despite low doses of rituximab, underlines rituximab’s efficacy.

Serum levels of immunoglobulin free light chains in patients with chronic hepatitis C presenting cryoglobulinemia

Hepatitis C virus (HCV) infects B-lymphocytes, provokes cellular dysfunction and causes lymphoproliferative diseases such as cryoglobulinemia and non-Hodgkin's B-cell lymphoma. In the present study, we investigated the serum levels of kappa and lambda free light chains (FLC) of immunoglobulins and the kappa/lambda FLC ratio in Brazilian patients with chronic HCV infection and cryoglobulinemia. We also analyzed the immunochemical composition of the cryoglobulins in these patients. Twenty-eight cryoglobulinemic HCV patients composed the target group, while 37 HCV patients without cryoglobulinemia were included as controls. The median levels of kappa and lambda FLC were higher in patients with cryoglobulinemia compared to controls (p=0.001 and p=0.003, respectively), but the kappa/lambda FLC ratio was similar in patients with and without cryoglobulinemia (p>0.05). The median FLC ratio was higher in HCV patients presenting with advanced fibrosis of the liver compared to HCV patients without fibrosis (p=0.004). Kappa and lambda FLC levels were strongly correlated with the IgA, IgG and IgM levels in the patients with cryoglobulinemia. In patients without cryoglobulinemia, the kappa FLC level was only correlated with the IgG level, whereas the lambda FLC were weakly correlated with the IgA, IgG and IgM levels. An immunochemical pattern of mixed cryoglobulins (MC), predominantly IgM, IgG, IgA and kappa light chain, was verified in these immune complexes. We concluded that HCV-infected patients presenting cryoglobulinemia have vigorous polyclonal B-lymphocyte activation due to chronic HCV infection and persistent immune stimulation.

THU0047 Baff and B2m, but not Free Light Chains, Correlate with Disease Activity in Primary SjÖGren's Syndrome (PSS)

BackgroundBoth kappa and lambda free light chain (FLC) levels appear to be elevated the serum of patients with pSS, in comparison to healthy controls [1,2]. Consequently, FLCs may represent potential...

Kappa Free Light Chains: Diagnostic and Prognostic Relevance in MS and CIS

BackgroundQuantification of kappa free light chains (KFLC) in cerebrospinal fluid shows high diagnostic sensitivity in multiple sclerosis and clinically isolated syndrome patients. However, a clearly defined threshold value is still missing and a possible prognostic value of the KFLC levels in these patients remains undefined.MethodsResults of KFLC quantification in 420 controls were used to set an upper limit of normal KFLC concentration in CSF under different blood-CSF-barrier conditions. Additionally, KFLC values of MS and CIS patients were assessed and results were evaluated with reference to the patients corresponding disease courses.ResultsThe calculated upper limit of normal KFLC-concentration covers 98% of these control patients. Using this cut-off, plasma cell activity in CSF can be detected in 97% of MS patients and in 97% of CIS patients. However, there is no evidence that the extent of KFLC elevation provides prognostic value in MS and CIS patients in this study.ConclusionKFLC determination should become a first line screen in the diagnostic algorithms of MS and CIS. The extent of elevation of intrathecal KFLC has no prognostic value on the disease course in MS and CIS patients.

Normalization of serum-free light chains in patients with systemic lupus erythematosus upon rituximab treatment and correlation with biological disease activity

Increased free light chain (FLC) levels have been reported as useful in various autoimmune conditions. We investigated how FLC concentrations change upon B cell targeted therapy in systemic lupus erythematosus (SLE) patients and if they correlate with disease activity. We retrospectively studied 11 SLE patients without renal failure, whom were treated with rituximab. Quantitative determination of IgG, IgA, IgM, and serum FLC was performed before and after rituximab. At baseline, 70% had abnormal serum FLC levels, including increased kappa and lambda levels, while the kappa/lambda ratio was normal for all. A strong correlation was observed between complement C3 fraction and kappa levels (r = -0.929, P < 0.001) or lambda levels (r = -0.854, P = 0.003), but not with IgG, IgA, or IgM levels. After rituximab treatment, kappa and lambda FLC concentrations decreased significantly whilst total concentrations of IgG, IgA, and IgM also decreased but remained within the normal range. There was a strong correlation only between kappa FLC levels and complement C3 fraction consumption (r = -0.543, P = 0.003). In SLE patients without renal failure, increased FLC levels (mainly kappa) with normal kappa/lambda ratios are a common feature, and in contrast to total IgG levels, FLC concentrations correlate with biological disease activity.

Elevated levels of kappa free light chains in CSF support the diagnosis of multiple sclerosis

Numerous studies have demonstrated elevated kappa free light chains (KFLCs) in CSF of multiple sclerosis (MS) patients. However, so far only small cohorts have been examined, and generally only through qualitative KFLCs analysis. Using a recently developed free light chain (FLC) immunoassay, it is now possible to quantitatively measure KFLCs by automated nephelometry. Our objective was to determine the extent to which KFLC levels in CSF correlated with the diagnosis of MS and CISSMS (clinically isolated syndrome suggestive of MS) compared to oligoclonal banding (OCB) and the immunoglobulin G (IgG) index. CSF and serum samples from 438 unselected patients, including a MS group of 70 patients (41 MS, 29 CISSMS), were analysed using nephelometry and isoelectric focusing. We then retrospectively correlated results with patients' diagnoses. Of the MS group (n = 70), 67 patients had elevated KFLCs using the KFLC index (> or = 5.9), 64 patients showed OCB and 56 patients presented with an elevated IgG index (> or = 0.6). Sensitivities were 0.96 for the KFLC index, 0.91 for OCB and 0.80 for the IgG index. The specificity of the KFLC index for the MS group (0.86) was lower than that of OCB (0.92) but distinctly higher compared to the IgG index (0.77). In this study, an elevated KFLC-index represented the most sensitive and specific quantitative diagnostic parameter for MS. As it is measured by automated, routinely available laboratory methods, KFLC quantitation can provide a rapid and reproduceable indication of intrathecal immunological processes supporting current MS diagnostic criteria.