Serum free light-chain measurements for identifying and monitoring patients with nonsecretory multiple myeloma

Prevalence and risk of progression of light-chain monoclonal gammopathy of undetermined significance: a retrospective population-based cohort study

BACKGROUND

Monoclonal gammopathy of undetermined significance (MGUS) is defined by expression of heavy-chain immunoglobulin (IgH) and is the precursor lesion for 80% of cases of multiple myeloma. The remaining 20% are characterised by absence of IgH expression; we aimed to assess prevalence of a corresponding precursor entity, light-chain MGUS.

METHODS

We used a population-based cohort, previously assembled to estimate MGUS prevalence, of 21,463 residents of Olmsted County, MN, USA, aged 50 years and older. We did a serum free light-chain assay on all samples with sufficient serum remaining, and immunofixation electrophoresis was done for all samples with an abnormal free light-chain ratio or abnormal protein electrophoresis results from the original study. Light-chain MGUS was defined as an abnormal free light-chain ratio with no IgH expression, plus increased concentration of the involved light chain. We calculated age-specific and sex-specific prevalence and rates of progression to lymphoproliferative disorders for light-chain and conventional MGUS and assessed incidence of renal disorders in patients with light-chain MGUS.

FINDINGS

610 (3.3%) of 18,357 people tested had an abnormal free light-chain ratio, of whom 213 had IgH expression that was diagnostic of conventional MGUS. 146 of the remaining 397 individuals had an increase of at least one free light chain and met criteria for light-chain MGUS. Prevalence of light-chain MGUS was 0.8% (95% CI 0.7-0.9), contributing to an overall MGUS prevalence of 4.2% (3.9-4.5). Risk of progression to multiple myeloma in patients with light-chain MGUS was 0.3% (0.1-0.8) per 100 person-years. 30 (23%) of 129 patients with light-chain MGUS were diagnosed with renal disease.

INTERPRETATION

We define a clinical entity representing the light-chain equivalent of conventional MGUS and posing a risk of progression to light-chain multiple myeloma and related disorders.

FUNDING

US National Cancer Institute.

Free light chain: a novel predictor of adverse outcome in chronic lymphocytic leukemia

OBJECTIVES

Chronic lymphocytic leukemia (CLL) is characterized by a highly variable clinical course. This retrospective study is planned to assess the prognostic value of serum free light chain (sFLC) levels and FLC ratio (FLCR) in CLL.

METHODS

Quantitative levels of sFLC were measured nephelometrically in sera collected at diagnosis. The expressions of ZAP70 and CD38 were quantified by flow cytometry. Chromosomal abnormalities were determined by interphase fluorescence in situ hybridization (FISH).

RESULTS

In a cohort of 101 patients with a median follow-up of 29 (1-234) months, sFLC levels were found to be high in 55 patients (54.5%). An abnormal FLCR was found in 30 patients (29.7%). FISH-based genetic risk groups did not differ significantly with respect to sFLC and FLCR (P > 0.05). Median time to first treatment was shorter in patients with high sFLC levels (P = 0.02). Median overall survival (OS) was shorter in patients with high sFLC levels (P = 0.01) and abnormal FLCR (P = 0.05). In patients with early stage disease, median OS was shorter in high sFLC (P = 0.03) and abnormal FLCR groups (P = 0.048). A relationship was observed between abnormal sFLC levels and CD38 positivity on logistic regression analysis (P = 0.003; OR: 4.44; 95% CI: 1.66-11.8).

CONCLUSIONS

This study highlighted the adverse prognostic impact of high sFLC levels and abnormal FLCR with regard to survival in CLL, even in early stage patients. Prospective studies are warranted to validate the adverse impact of sFLC and FLCR on clinical outcome.

Circulating serum free light chains as predictive markers of AIDS-related lymphoma

PURPOSE HIV-infected persons have an elevated risk of developing non-Hodgkin's lymphoma (NHL); this risk remains increased in the era of effective HIV therapy. We evaluated serum immunoglobulin (Ig) proteins as predictors of NHL risk among HIV-infected individuals. PATIENTS AND METHODS By using three cohorts of HIV-infected persons (from 1982 to 2005), we identified 66 individuals who developed NHL and 225 matched (by cohort, sex, ethnicity, age, and CD4 count), HIV-infected, lymphoma-free controls who had available stored prediagnostic blood samples. Serum/plasma samples obtained 0 to 2 years and 2 to 5 years before diagnosis/selection were assayed for IgG, IgM, and IgA levels; monoclonal (M) Igs; and kappa and lambda free light chain (FLC) levels. Patients and matched controls were compared by using conditional logistic regression. Results The kappa and lambda FLCs were both significantly higher in patients (eg, in 2- to 5-year window: median kappa, 4.24 v 3.43 mg/dL; median lambda, 4.04 v 3.09 mg/dL) and strongly predicted NHL in a dose-response manner up to 2 to 5 years before diagnosis/selection (eg, NHL risk 3.76-fold higher with kappa concentration at least 2.00 times the upper limit of normal, and 8.13-fold higher with lambda concentration at least 2.00 times the upper limit of normal compared with normal levels). In contrast, IgG, IgM, and IgA levels were similar in patients and controls. M proteins were detected in only two patients with NHL (3%) and in nine controls (4%), and they were not significantly associated with NHL risk. CONCLUSION Elevated FLCs may represent sensitive markers of polyclonal B-cell activation and dysfunction and could be useful for identifying HIV-infected persons at increased NHL risk.

Evidence of serum immunoglobulin abnormalities up to 9.8 years before diagnosis of chronic lymphocytic leukemia: a prospective study

Immune-related deficiencies are well-known complications of chronic lymphocytic leukemia (CLL). Although recent data indicate that almost all CLL patients are preceded by a monoclonal B-cell lymphocytosis precursor state, patterns of immune defects preceding CLL diagnosis are unclear. We identified 109 persons who developed CLL from the prospective and nationwide Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial with 77 469 participants, with serially collected prediagnostic serum samples. We assayed monoclonal (M)-proteins, kappa/lambda free light chains (FLCs) in prediagnostic obtained up to 9.8 years before CLL diagnosis. The prevalence of an abnormal FLC ratio, M-protein, and hypogamma-globulinemia before CLL diagnosis was 38% (95% confidence interval, 29%-47%), 13% (7%-21%), and 3% (1%-8%), respectively. M-proteins and abnormal FLC ratios were detected up to 9.8 years before CLL diagnosis in a total of 48 persons (44%). Hypogammaglobulinemia was not present until 3 years before the diagnosis of CLL. Among 37 patients with information on tumor cell immunophenotype, an association between immunophenotype and involved FLC (P = .024, Fisher exact test) was observed. Among 61 persons with a normal FLC ratio and without an M-protein, 17 had elevated kappa and/or lambda FLC levels, indicating polyclonal B-cell activation in 17 of 109 (16%) patients. These findings support a role for chronic immune stimulation in CLL genesis.

The role of complete response in multiple myeloma

In multiple myeloma (MM), the impact of complete response (CR) could be shown only after introduction of high-dose therapy plus autologous stem cell transplantation (ASCT). In the context of ASCT, achieving CR (negative immunofixation and normal bone marrow) or at least very good partial response is associated with longer progression-free survival and in most studies longer survival. With novel agents, high CR rates are achieved and this prognostic impact of CR is being shown as well, both in relapsed and in newly diagnosed MM. However the benefit of CR achievement depends on the type of treatment and is not identical for all patients. In elderly patients, treatments inducing more CR may be more toxic. Although CR achievement is necessary in patients with poor-risk disease, it might not be as critical for long survival in more indolent MM. CR achievement is not the only objective of treatment because it is possible to further improve the depth of response and the outcome by continuing treatment after CR achievement. Finally, there are several levels of CR and in the future it will be necessary to confirm the prognostic impact of immunophenotypic or molecular CR or of CR defined by imaging procedures.

Serum free light chain immunoassay as an adjunct to serum protein electrophoresis and immunofixation electrophoresis in the detection of multiple myeloma and other B-cell malignancies

BACKGROUND

Protein and immunofixation electrophoresis of serum and urine are established as diagnostic aids for identifying monoclonal gammopathies. However, many patient sera sent to laboratories are not accompanied by urine samples and recent reports suggest the use of serum free light chain (sFLC) analysis in combination with serum protein electrophoresis (SPE) and immunofixation electrophoresis (lFE) could eliminate the need for urinalysis. The aim of the study was to assess the utility of sFLC measurement in addition to serum protein electrophoresis in the identification of patients with B-cell malignancies.

METHODS

A total of 952 serum samples were analysed by serum protein electrophoresis and those with abnormal bands were analysed by immunofixation. sFLCs were measured in a retrospective manner by automated assay.

RESULTS

In our study of 952 patient sera, it was found that FLC analysis identified 23 additional cases of B-cell malignancies which were missed by SPE.

CONCLUSIONS

The additional malignancies identified by sFLC analysis add support for its inclusion in the routine screening protocol for B-cell malignancies.

Serum free light chain assay reduces the need for serum and urine immunofixation electrophoresis in the evaluation of monoclonal gammopathy

Background

The potential for serum free light chain (sFLC) assay measurements to replace urine electrophoresis (uEPG) and to also diminish the need for serum immunofixation (sIFE) in the screening for monoclonal gammopathy was assessed. A testing algorithm for monoclonal protein was developed based on our data and cost analysis.

Methods

Data from 890 consecutive sFLC requests were retrospectively analysed. These included 549 samples for serum electrophoresis (sEPG), 447 for sIFE, and 318 for uEPG and urine immunofixation (uIFE). A total of 219 samples had sFLC, sEPG, sIFE and uEPG + uIFE performed. The ability of different test combinations to detect the presence of monoclonal proteins was compared.

Results

The sFLC κ/ λ ratio (FLC ratio) indicated monoclonal light chains in 12% more samples than uEPG + uIFE. The combination of sEPG and FLC ratio detected monoclonal proteins in 49% more samples than the combination of sEPG and sIFE. Furthermore, the sEPG + FLC ratio combination detected monoclonal protein in 6% more samples than were detected by the combined performance of sEPG, sIFE, uEPG and uIFE. However, non-linearity of the assay, the expense of repeat determinations due to the narrow measuring ranges, and frequent antigen excess checks were found to be limitations of the sFLC assay in this study.

Conclusion

The FLC ratio is a more sensitive method than uIFE in the detection of monoclonal light chains and may substantially reduce the need for onerous 24 h urine collections. Our proposed algorithm for the evaluation of monoclonal gammopathy incorporates the sFLC assay, resulting in a reduction in the performance of labour intensive sIFE and uEPG + uIFE while still increasing the detection of monoclonal proteins.

Oligo-secretory myeloma in a patient with ankylosing spondylitis

Non-secretory myeloma is a plasma cell dyscrasia characterized by the absence of serum and urinary monoclonal immunoglobulins on electrophoretic tests. Because of the lack of monoclonal protein, the identification of the disease is more difficult than for secretory myelomas. The coexistence of ankylosing spondylitis and multiple myeloma has been reported occasionally. We report a rare case of oligo-secretory myeloma coexistent with ankylosing spondylitis.

The relationship between the serum free light chain assay and serum immunofixation electrophoresis, and the definition of concordant and discordant free light chain ratios

“Stringent” complete remission in myeloma has been defined by a normal serum free light chain ratio (SFLCR) in addition to the standard criteria for CR. 2648 serial samples from 122 IgG or IgA myeloma patients were studied to explore the relationship between SFLCR and serum immunofixation electrophoresis (SIFE). SFLCR was normal in 34% of cases with positive SIFE and abnormal in 66%. SFLCR was normal in 69% of cases with negative SIFE and abnormal in 31%. When evaluated with SIFE as the benchmark, the sensitivity of SFLCR was 66% and specificity was 69%. These findings were unchanged when abnormal SFLCR values were classified as concordant (< 0.26 for λ disease and > 1.65 for κ) or discordant (< 0.26 for κ disease and > 1.65 for λ). Additional studies are required to determine the temporal relationship between SFLCR normalization and paraprotein clearance. Until then, the role of SFLCR in defining response remains controversial.

Screening panels for detection of monoclonal gammopathies

BACKGROUND

The repertoire of serologic tests for identifying a monoclonal gammopathy includes serum and urine protein electrophoresis (PEL), serum and urine immunofixation electrophoresis (IFE), and quantitative serum free light chain (FLC). Although there are several reports on the relative diagnostic contribution of these assays, none has looked at the tests singly and in combination for the various plasma cell proliferative disorders (PCPDs).

METHODS

Patients with a PCPD and all 5 assays performed within 30 days of diagnosis were included (n = 1877). The diagnoses were multiple myeloma (MM) (n = 467), smoldering multiple myeloma (SMM) (n = 191), monoclonal gammopathy of undetermined significance (MGUS) (n = 524), plasmacytoma (n = 29), extramedullary plasmacytoma (n = 10), Waldenström macroglobulinemia (WM) (n = 26), primary amyloidosis (AL) (n = 581), light chain deposition disease (LCDD) (n = 18), and POEMS syndrome (n = 31).

RESULTS

Of the 1877 patients, 26 were negative in all assays. Omitting urine from the panel lost an additional 23 patients (15 MGUS, 6 AL, 1 plasmacytoma, 1 LCDD), whereas the omission of FLC lost 30 patients (6 MM, 23 AL, and 1 LCDD). The omission of serum IFE as well as urine lost an additional 58 patients (44 MGUS, 7 POEMS, 5 AL, 1 SMM, and 1 plasmacytoma).

CONCLUSIONS

The major impact of using a simplified screening panel of serum PEL plus FLC rather than PEL, IFE, and FLC is an 8% reduction in sensitivity for MGUS, 23% for POEMS (7 patients), 4% for plasmacytoma (1 patient), 1% for AL, and 0.5% for SMM. There is no diminution in sensitivity for detecting MM, macroglobulinemia, and LCDD.

Serum free light chain ratio, total kappa/lambda ratio, and immunofixation results are not prognostic factors after stem cell transplantation for newly diagnosed multiple myeloma

BACKGROUND

The prognostic value of changes in paraprotein markers after stem cell transplantation is unknown. We evaluated disease response using serum immunofixation (s-IFIX), total kappa and lambda ratio (KLR), and free light chain (FLC) ratio in myeloma patients who underwent autologous or autologous plus allogeneic stem cell transplantation.

METHODS

We studied s-IFIX, KLR, and FLC ratio in sera from 203 patients, 3 months after transplantation. We evaluated overall and event-free survival (OS and EFS, interval between date of study enrollment and date of death from any cause or date of progression, relapse, or death from any cause, respectively) by the Kaplan-Meier method.

RESULTS

Of the 203 patients, 51 were negative by s-IFIX, 99 reached a normal KLR, and 92 had a normal FLC ratio. Of the 51 patients with negative s-IFIX, 40 (78%) also had a normal FLC ratio. The median duration of OS was 54.3 months, and the median EFS was 19.5 months. None of the measured paraprotein parameters showed an association with OS. Only a normal KLR was associated with prolonged EFS (P = 0.016). Even a negative s-IFIX associated with a normal FLC ratio did not show a significant difference in terms of EFS and OS.

CONCLUSIONS

Our analysis with a small cohort of patients did not show a significant impact of achieving complete response (CR) or stringent CR on patient survival.

Are renal reference intervals required when screening for plasma cell disorders with serum free light chains and serum protein electrophoresis?

Renal impairment and polyclonal hypergammaglobulinemia may abnormally increase the serum free light chain (sFLC) ratio, giving false-positive results with current reference intervals. We measured sFLCs with concomitant serum protein electrophoresis (SPEP) and urine protein electrophoresis (UPEP) in 281 patients. Results were interpreted relative to renal function (serum creatinine concentrations) and polyclonal hypergammaglobulinemia. Overall, 78 plasma cell disorders (PCDs) were detected with the serum panel of SPEP/sFLC vs 76 with SPEP/UPEP. In 13 samples with negative SPEP/UPEP, mildly increased ratios up to 3.1 (normal, 0.26-1.65) were observed: 10 were associated with increased serum creatinine and 1 with polyclonal hypergammaglobulinemia; 2 were unassociated with either condition. In 2 samples, decreased kappa/lambda ratios were identified that were clinically significant despite normal SPEP/UPEP. Two monoclonal gammopathies were identified with UPEP and sFLC, but samples were normal with SPEP. Screening for PCDs with a serum panel consisting of SPEP and the sFLC assays is a highly sensitive approach that could eliminate the need for UPEP. A mildly increased kappa/lambda ratio up to 3.1 was observed with increased serum creatinine and/or polyclonal hypergammaglobulinemia that was consistent with pathophysiologic changes, and, therefore, renal reference intervals are recommended.

Monoclonal gammopathy of undetermined significance (MGUS) consistently precedes multiple myeloma: a prospective study

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant plasma-cell proliferative disorder associated with a life-long risk of progression to multiple myeloma (MM). It is not known whether MM is always preceded by a premalignant asymptomatic MGUS stage. Among 77,469 healthy adults enrolled in the nationwide population-based prospective Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial, we identified 71 subjects who developed MM during the course of the study in whom serially collected (up to 6) prediagnostic serum samples obtained 2 to 9.8 years prior to MM diagnosis were available. Using assays for monoclonal (M)-proteins (electrophoresis/immunofixation) and kappa-lambda free light chains (FLCs), we determined longitudinally the prevalence of MGUS and characterized patterns of monoclonal immunoglobulin abnormalities prior to MM diagnosis. MGUS was present in 100.0% (87.2%-100.0%), 98.3% (90.8%-100.0%), 97.9% (88.9%-100.0%), 94.6% (81.8%-99.3%), 100.0% (86.3%-100.0%), 93.3% (68.1%-99.8%), and 82.4% (56.6%-96.2%) at 2, 3, 4, 5, 6, 7, and 8+ years prior to MM diagnosis, respectively. In approximately half the study population, the M-protein concentration and involved FLC-ratio levels showed a yearly increase prior to MM diagnosis. In the present study, an asymptomatic MGUS stage consistently preceded MM. Novel molecular markers are needed to better predict progression to MM in patients with MGUS.

Immunoglobulin free light chains: do they have a role in plasma cell leukemia?

The assay of serum free light chains (FLCs) is established in the diagnosis and prognosis of several plasma cell dyscrasias, but its significance in plasma cell leukemia (PCL) has not been reported so far. PCL is a rare and aggressive disease with a poor prognosis. The authors describe two cases of PCL with divergent clinical profiles where the serum FLC assay was available. Although both patients had greatly elevated serum beta(2)-microglobulin, one patient had much higher levels of serum FLCs and evidence of renal impairment, which were absent in the other; however, the latter, who had multisystem involvement, showed a more rapidly downhill course with early mortality.

International Myeloma Working Group guidelines for serum-free light chain analysis in multiple myeloma and related disorders

The serum immunoglobulin-free light chain (FLC) assay measures levels of free kappa and lambda immunoglobulin light chains. There are three major indications for the FLC assay in the evaluation and management of multiple myeloma and related plasma cell disorders (PCD). In the context of screening, the serum FLC assay in combination with serum protein electrophoresis (PEL) and immunofixation yields high sensitivity, and negates the need for 24-h urine studies for diagnoses other than light chain amyloidosis (AL). Second, the baseline FLC measurement is of major prognostic value in virtually every PCD. Third, the FLC assay allows for quantitative monitoring of patients with oligosecretory PCD, including AL, oligosecretory myeloma and nearly two-thirds of patients who had previously been deemed to have non-secretory myeloma. In AL patients, serial FLC measurements outperform PEL and immunofixation. In oligosecretory myeloma patients, although not formally validated, serial FLC measurements reduce the need for frequent bone marrow biopsies. In contrast, there are no data to support using FLC assay in place of 24-h urine PEL for monitoring or for serial measurements in PCD with measurable disease by serum or urine PEL. This paper provides consensus guidelines for the use of this important assay, in the diagnosis and management of clonal PCD.

Comparable outcomes in nonsecretory and secretory multiple myeloma after autologous stem cell transplantation

Nonsecretory myeloma (NSM) accounts for <5% of cases of multiple myeloma (MM). The outcome of these patients following autologous stem cell transplantation (ASCT) has not been evaluated in clinical trials. We compared the outcomes after ASCT for patients with NSM reported to the Center for International Blood and Marrow Transplant Research (CIBMTR) between 1989 and 2003, to a matched group of 438 patients (4 controls for each patient) with secretory myeloma (SM). The patients were matched using propensity scores calculated using age, Durie-Salmon stage, sensitivity to pretransplant therapy, time from diagnosis to transplant, and year of transplant. Disease characteristics were similar in both groups at diagnosis and at transplant except higher risk of anemia, hypoalbuminemia, and marrow plasmacytosis (in SM) and plasmacytoma (more in NSM). Cumulative incidence of treatment-related mortality (TRM), relapse, progression-free survival (PFS), and overall survival (OS) were similar between the groups. In multivariate analysis, based on a Cox model stratified on matched pairs and adjusted for covariates not considered in the propensity score, we found no difference in outcome between the NSM and SM groups. In this large cohort of patients undergoing ASCT, we found no difference in outcomes of patients with NSM compared to those with SM.

Abnormal serum free light chain ratios are associated with poor survival and may reflect biological subgroups in patients with chronic lymphocytic leukaemia

The measurement of immunoglobulin serum free light chains (sFLC) has prognostic significance in plasma cell dyscrasias but its role in chronic lymphocytic leukaemia (CLL) is unknown. This retrospective study from three UK hospitals analysed sFLC in 181 untreated/pre-treatment CLL patients and 78 treated CLL patients, with samples taken later in their disease. An abnormal sFLC ratio was significantly associated with poor overall survival for the 181 untreated/pre-treatment patients (P = 0.0001) and for all patients (P = 0.002), irrespective of cause of death. Using multivariate analysis (n = 194), four independent prognostic variables for overall survival were identified namely Zap-70 (P = 0.0001), beta2M (P = 0.01), IGHV mutation status (P = 0.017) and an abnormal sFLC ratio (P = 0.024). For CLL patients with unmutated IGHV genes, elevated kappa/lambda ratios were adversely prognostic. For patients with mutated IGHV genes, reduced kappa/lambda ratios were adversely prognostic and associated with the poor prognostic IGHV3-21, IGHV3-48 and IGHV3-53 subgroups, suggesting an abnormal sFLC ratio may reflect biological subgroups within CLL. Abnormal sFLC ratios need to be studied prospectively in CLL patients and the biological rationale for their abnormality investigated.

Immunodiagnostic capabilities of anti-free immunoglobulin light chain monoclonal antibodies

Overproduction of plasma cell-derived monoclonal free kappa or lambda immunoglobulin light chains (FLCs) is a hallmark of multiple myeloma, AL amyloidosis, and light chain deposition disease. Because these components serve as unique cellular and serologic biomarkers, their detection and quantitation has diagnostic, therapeutic, and prognostic import. In this regard, we have developed monoclonal antibodies (mAbs) that specifically recognize the kappa or lambda FLC products of all known human variable and constant region light chain genes. We now report the results of our studies that have demonstrated the capability of these reagents to measure, in a modified fluid-phase capture enzyme-linked immunosorbent assay (ELISA), serum kappa and lambda FLCs at concentrations as low as 5 and 15 ng/mL, respectively. The mAb-based ELISA has greater sensitivity and reproducibility than does the commercially available immunoturbidimetric assay that uses polyclonal anti-FLC antibodies. In addition, the mAbs can immunostain monoclonal FLC-producing plasma cells and pathologic light chain-related amyloid and nonfibrillar tissue deposits. Our anti-FLC mAbs, with their high degree of reactivity and versatility, may provide an invaluable tool in the diagnosis and management of light chain-associated disease.

Quantitation of serum free light chains in combination with protein electrophoresis and clinical information for diagnosing multiple myeloma in a general hospital population

BACKGROUND

Serum free light chain (SFLC) measurements have recently come into use as an aid for diagnosing monoclonal gammopathy. We evaluated SFLC measurements in combination with serum protein electrophoresis (SPE) and clinical information for diagnosing multiple myeloma (MM) in a hospital population.

METHODS

We measured SFLCs in 3818 sera received for SPE over a 1-year period when patient symptoms or biochemical findings suggested myeloma-related tissue damage (n = 1067). We reviewed SPE and SFLC results from 489 patients together with their final diagnoses obtained from the hospital information technology department.

RESULTS

SFLC measurement, combined with SPE and clinical information, allowed identification of 95% of patients (38 of 40) with previously undiagnosed MM, macroglobulinemia, or primary amyloidosis. Additionally, we identified 45 patients with monoclonal gammopathy of undetermined significance (MGUS) and 4 with plasmacytoma. Of patients followed at our hospital in whom SFLCs were not measured, only 1 patient was diagnosed with MM. This patient had anemia and was mistakenly not tested for SFLCs. An abnormal kappa/lambda ratio was found in 26 of 29 patients with MM but also in 36 of 203 patients with renal impairment, polyclonal immunoresponse, or other nonhematological diagnoses. None of the 203 patients with nonhematological disease had a kappa/lambda ratio <0.05 or >10.

CONCLUSIONS

The combined use of SPE, SFLC measurements, and clinical criteria allows MM to be efficiently diagnosed or excluded based on serum measurements only.

Prognostic value of the serum free light chain ratio in newly diagnosed myeloma: proposed incorporation into the international staging system

To determine if the serum free light chain (FLC) ratio has prognostic value in patients with symptomatic multiple myeloma (MM), baseline serum samples from a well-characterized cohort of 790 newly diagnosed MM patients were tested with the FLC assay. FLC ratio was calculated as kappa/lambda (reference range 0.26-1.65). On the basis of the distribution of values, a cutpoint kappa/lambda FLC ratio of <0.03 or >32 was chosen for further analysis. Overall survival was significantly inferior in patients with an abnormal FLC ratio of <0.03 or >32 (n=479) compared with those with an FLC ratio between 0.03 and 32 (n=311), with median survival of 30 versus 39 months, respectively. We incorporated abnormal FLC ratio with the International Staging System (ISS) risk factors (that is, albumin <3.5 g/dl and serum beta(2)-microglobulin >or=3.5 g/l), to create a risk stratification model with improved prognostic capabilities. Patients with 0, 1, 2 or 3 adverse risk factors had significantly different overall survival, with median survival times of 51, 39, 30 and 22 months, respectively (P<0.001). These findings suggest that the serum FLC ratio at initial diagnosis is an important predictor of prognosis in myeloma, and can be incorporated into the ISS for improved risk stratification.

[Bortezomib in relapsed or refractory multiple myeloma: results in a cohort of 39 patients]

INTRODUCTION

Bortezomib has presently become a significant rescue treatment in multiple myeloma (MM) due to its observed effectiveness and safety in multicenter trials. We have aimed to verify both aspects in a setting of non-selected patients.

PATIENTS AND METHODS

This is an observational, prospective study of the cohort of relapsed or refractory MM patients treated with bortezomib in our Department. The variables analyzed were response, its duration, time to the treatment failure (TTF), overall survival (OS), response related conditions and toxicity. Statistical methods used were Fisher's exact test, log rank-test and Kaplan-Meier survival tables.

RESULTS

A total of 39 patients, 25 relapsed and 14 refractory to chemotherapy, started the treatment. The mean number of previous treatment was 2.3 and they received an average of 5.8 cycles of bortezomib. Complete response was achieved in 14 patients (36%), partial response in 12 (31%) and minor or no response in 13 ones (33%). Median duration of response was 8 months, median TTF was 10 months and median OS, from the onset of bortezomib was 16.5 months, with a median observation of live patients of 12.5 months. The response was more frequent in males (p = 0.019) and in patients with one previous treatment (p = 0.15). There were no significant differences regarding to TTF when we considered the cause of treatment (relapse or no response to chemotherapy) nor in the number of previous treatment regimes. The most frequent adverse events were reversible thrombocytopenia (31%), polyneuropathy (28%) and asthenia-anorexia (23%).

CONCLUSIONS

In our cohort of non-selected, relapsed or refractory MM patients, the observations found in the multicenter randomized trials results regarding response rate and duration, TTF OS and safety of bortezomib therapy were verified.

Appraisal of immunoglobulin free light chain as a marker of response

The immunoglobulin free light chain (FLC) assay is an invaluable tool for following patients with oligosecretory plasma cell dyscrasia. Baseline values have also been shown to be prognostic in all plasma cell disorders tested. A looming question, however, is the role it should play in following myeloma patients with disease that is measurable using serum and urine electrophoresis. We used the data and stored samples from a mature Eastern Cooperative Oncology Group clinical trial (E9486) to assess serum levels of FLC at baseline and after 2 months of alkylator-based therapy. For serial determinations, the absolute level of involved serum FLC or the difference of the involved and uninvolved FLC is preferred over the ratio of involved to uninvolved FLC. FLC response after 2 months of therapy was superior to early M-protein measurement to predict overall response. The ideal cut-point for FLC change appears to be between 40% and 50% reduction. The correlation between serial measurements of serum FLC and urine M-protein is inadequate to abolish the serial 24-hour urine protein. Although baseline values of FLC are prognostic in newly diagnosed myeloma patients, serial measurements do not appear to have added value in patients who have M-proteins measurable by electrophoresis.

Immunoglobulin and free light chain abnormalities in Gaucher disease type I: data from an adult cohort of 63 patients and review of the literature

Gaucher disease type I, the most common lysosomal storage disorder, is associated with immunoglobulin abnormalities. We studied the prevalence, risk factors, pathogenesis, and effect of enzyme relation therapy (ERT) on gammopathies in an adult Gaucher disease type I cohort (N = 63) and related the results to a review of the currently available literature. Polyclonal gammopathies and monoclonal gammopathy of undetermined significance (MGUS) in our adult GD I cohort were found in 41% and 19% of patients. These results are similar to the data from the literature and correspond to the increased risk of multiple myeloma (MM) that has been described. The prevalence of MGUS in our cohort increased with age but was not associated with disease severity or exposure time. The serum levels of free light chains of immunoglobulins were measured and were not found predictive for the development of MGUS or MM. Levels of pro- as well as anti-inflammatory cytokines, growth factors, and chemokines, especially those involved in inflammation and B-cell function, are disturbed in GD I, with the most impressive and consisting elevations for interleukin-10 and pulmonary and activation-regulated chemokine. A beneficial effect of ERT on the occurrence and progression of gammopathies was suggested from longitudinal data.

Value of serum free light chain testing for the diagnosis and monitoring of monoclonal gammopathies in hematology

The automated quantification of serum free kappa and lambda light chain concentrations provides a highly sensitive tool for the diagnosis and monitoring of monoclonal gammopathies. An abnormal kappa:lambda ratio supports the presence of clonal plasma cell expansion and requires further investigation. More than 94% of myeloma, light chain myeloma, and AL amyloidosis and, likewise, a majority of patients with light chain deposition disease are detectable with this technology. Importantly, these assays identify M-proteins in most patients with oligosecretory disease and permit their recruitment into clinical trials from which they have been previously excluded. Combining serum free light chain testing with traditional electrophoresis provides > 99% accuracy in the first-line diagnosis of monoclonal gammopathies and eliminates the need for urine testing in most instances. One third of patients with monoclonal gammopathy of undetermined significance have an abnormal free light chain ratio, and these patients harbor a greater risk of progression to plasma cell dyscrasia. For monitoring response to therapy, the international uniform response criteria define a normal free light chain ratio as an essential element of the "stringent complete response" category. Because the half-life of free light chains is < 6 hours, free light chain measurements at short sampling intervals allow real-time measurement of treatment-induced tumor kill, and provide prompt indications of chemosensitivity, dose adequacy, need for alternative approaches, and even prognosis, as demonstrated in AL amyloidosis if the involved free light chain concentration normalizes. Clinical applications of these assays will likely increase as their utility is more widely explored.

Investigative Tools for Diagnosis and Management

Recent advances in genomics and proteomics have advanced our understanding of myeloma pathogenesis, recognized novel mediators of disease process, and identified new therapeutic targets. These developments have provided newer diagnostic tools for myeloma, improved monitoring of the disease status and allowed for molecular classification of the disease. The recent advances in investigative techniques that have helped refine the diagnostic work up in myeloma includes use of serum free light chains, especially in oligosecretory myeloma, patients with renal disease and with amyloidosis; use of MRI and PET scan in diagnosis and managing bone disease; and use of cytogenetics and fluorescent in situ hybridization (FISH) technique to determine prognosis. Newer risk stratification protocols have included international staging systems as well as FISH-detected chromosomal changes, specifically t(4;14), t(14;16), and del 17p. These improved predictive risk stratification models are guiding treatment algorithms. As the novel therapies are able to attain complete responses in a significant number of patients, the response categories are also being redefined. Immunophenotypic identification of clonal plasma cells, inclusion of free light chain response and molecular markers of disease now allow us to define stringent complete responses. Recent studies show the increasing importance of attaining complete remission to extended overall survival. The ongoing oncogenomic studies including high-throughput expression profiling, high-density single nucleotide polymorphism (SNP)–arrays and array based comparative hybridization (aCGH) have been utilized to not only understand myeloma pathobiology, but for gene discovery, identification of biomarkers, and delineation of patient subgroups to incorporate them into therapeutic strategies and to eventually provide optimal individualized therapy.

Long-term follow-up of plasma cells in bone marrow and serum free light chains in primary systemic AL amyloidosis

OBJECTIVE

Primary systemic AL amyloidosis arises from immunoglobulin light chains produced by plasma cell dyscrasia. To prospectively investigate the production of M-protein and plasma cells in bone marrow before and after chemotherapy, we performed flow cytometry and analysis of serum free light chains (FLCs).

PATIENTS AND METHODS

Fifty-nine patients with primary systemic AL amyloidosis (mean age, 59.9+/-8.8 years) were enrolled in this study, and of these 31 were serially studied before and after chemotherapy. Complete hematological remission was defined as normalization of the FLC kappa/lambda ratio.

RESULTS

MPC-1(-)CD45(-) (p<0.05) and MPC-1(+)CD45(-)CD49e(-) (p<0.005) were significantly higher, and MPC-1(-)-CD45(+) (p<0.05), MPC-1(+)CD45(+)CD49e(-) (p<0.0001) and MPC-1(+)CD45(+)CD49e(+) (p<0.0005) were significantly lower in the patients with AL amyloidosis than in controls. There was a significantly positive correlation between the serum predominant FLC/serum creatinine ratio and MPC-1(+)CD45(-)CD49e(-) (p<0.05). After chemotherapies, such as high-dose melphalan with autologous stem cell support, 20 of 31 patients with AL amyloidosis achieved complete hematological remission. There were no significant differences in any subtype of plasma cells before treatment between the remission and non-remission groups, but in the former group MPC-1(+)CD45(-)CD49e(-) and MPC-1(-)CD45(+) were significantly decreased and increased after chemotherapy compared with before, respectively.

CONCLUSION

Abnormal plasma cells in the bone marrow, particularly the MPC-1(+)CD45(-)CD49e(-) subset, may be important as a follow-up marker before and after chemotherapy in primary systemic AL amyloidosis. These cells maintain low levels as long as no relapse occurs.

The Importance of Free Light Chains of Immunoglobulins Determination in Serum

For many years, Bence Jones proteinuria has been an important diagnostic marker for multiple myeloma. Relatively new serum tests for free kappa and free lambda light chains of immunoglobulins reflect the production of free light chains more accurately than urine tests. In this study, we examined the value of serum free light chains measurement in the diagnosis of some neoplastic diseases and the discrepance between the findings of serum protein electrophoresis and serum free light chains. Thirty one patients (f=19, m=12) were included in the study, most of them with blood malignant diseases. The results show that in six patients with normal gamma and beta electrophoresis fractions there are abnormal levels of free light chains and/or an abnormal κ/LD ratio. In 20 patients we found an abnormal κ/LD ratio, and in 21 patients we found an abnormal κ or LD level, or both. The obtained results show the important role of serum free light chains determination in identifying patients with monoclonal gammopathies.

Assessment of free light chains in the cerebrospinal fluid of patients with lymphomatous meningitis - a pilot study

BACKGROUND

Lymphomatous meningitis (LM) represents a severe complication of malignant lymphomas. While clinical suspicion is raised by symptoms ranging from mild disturbances of sensation to severe pain or impaired consciousness, the definite diagnosis of LM is often difficult to obtain. Since B-cell lymphomas are clonally restricted to express either kappa or lambda immunoglobulin light chain, we hypothesised that analysis of free light chain (FLC) ratios might facilitate the diagnosis of LM.

METHODS

Kappa and lambda FLC were measured using a novel nephelometric assay in cerebrospinal fluid (CSF) and serum from 17 patients. 5/17 suffered from LM as demonstrated by cytology, immunocytology, and/or imaging procedures.

RESULTS

Measurement of FLC concentrations in CSF was achieved for all 17 patients. FLC levels in CSF were lower than serum FLC levels in samples for the same patient obtained at the same time (p < 0.01). CSF and serum FLC concentrations correlated weakly in all patients irrespective of LM status. Significantly more patients with cytopathologically and immunohistochemically proven LM displayed abnormal kappa/lambda FLC ratios in CSF compared to individuals with no LM (p < 0.01).

CONCLUSION

This is the first report demonstrating that a significant proportion of LM patients display an abnormal kappa/lambda FLC ratio in the CSF.

Intérêt du dosage des chaînes légères libres d'immunoglobulines sériques pour le diagnostic et le suivi des gammapathies monoclonales

PURPOSE

Monoclonal immunoglobulin free light chains (FLC) are present in the serum and urine of many patients with monoclonal gammopathies. In this review, we discuss the usefulness of serum FLC determination for diagnostic, prognostic and monitoring of multiple myeloma (MM), AL amyloidosis and monoclonal gammopathies of undetermined significance (MGUS).

CURRENT KNOWLEDGE AND KEY POINTS

Serum FLC assay is a useful laboratory test for management of light chain MM, non-secretory MM and AL amyloidosis. Currently, serum FLC testing cannot be recommended for monitoring intact immunoglobulin multiple myeloma. Even though serum FLC determination give a better risk stratification for MGUS, systematic serum FLC assay should not be used in routine because of high MGUS occurrence in the general population.

FUTURE PROSPECTS AND PROJECTS

Further prospective studies with large cohorts of patients should provide additional evidence for the role of serum FLC measurement in patients with intact immunoglobulin multiple myeloma.

[Multiple myeloma]

Multiple myeloma is the second most common hematological malignancy. It is defined by the presence of monoclonal plasma cells capable to produce a monoclonal paraprotein causing clinical abnormalities such as anemia, renal insufficiency, hypercalcemia, or bone lesions. New chromosomal or molecular abnormalities have been identified allowing a better management. Multiple myeloma is treatable and, although it remains incurable, the patient prognosis and quality of life has notably improved, so it is not rare to see series with a median survival longer than 5 years. Even more, it is possible by now to expect improvements respect to the standard autologous stem cell transplantation. This must be attributed to the emergence of a number of new therapies entering clinical practice over the last 6 years: thalidomide (Thalidomid Pharmion, Boulder, CO, USA), lenalidomide (Revlimid, Celgene Corporation, Summit, NJ, USA) and bortezomib (Velcade, Janssen Pharmaceutica N.V., Belgium). Finally, we also will review the current clinical experience in supportive therapy, which has also contributed to the patient outcome improvement with approaches such as: new indications for dialysis, use of erythropoietin receptor stimulating agents and bisphosphonates, and new surgical therapies such as vertebroplastia and kyphoplastia.

Diagnostic and prognostic utility of the serum free light chain assay in patients with AL amyloidosis

BACKGROUND

Organ dysfunction in AL amyloidosis is related to the production and deposition of amyloidogenic monoclonal light chains. These pathological light chains can now be quantified using the recently developed serum free light chain assay.

METHODS

We retrospectively reviewed 31 patients with AL amyloidosis to determine the frequency of abnormal free light chain assay results at diagnosis and whether changes in the serum free light chain assay predict outcome after therapy.

RESULTS

An abnormal free light chain assay was found in 30 of 31 patients (97%) at the time of diagnosis. In the subset of our patients who received treatment for AL amyloidosis, a >50% reduction of the pathological free light chain following treatment was shown to predict improved overall survival. In our series of analyses, achievement of greater magnitudes of reduction of the free light chain result did not appear to provide additional prognostic information, nor did the baseline free light chain result predict outcome.

CONCLUSION

Our findings support the use of the free light chain assay in the diagnostic work-up of patients with suspected AL amyloidosis, and also as a sensitive biomarker of response to therapy.