Serum free light chains in myeloma patients with an intact M protein by immunofixation: potential roles for response assessment and prognosis during induction therapy with novel agents

[The roles of serum free light chain ratio in the diagnosis and prognosis of newly diagnosed multiple myeloma]

OBJECTIVE

The roles of serum free light chain ratio (sFLCR) in the diagnosis and prognosis of newly diagnosed multiple myeloma (NDMM) patients were analyzed.

METHODS

The clinical data was retrospectively analyzed for 82 newly diagnosed multiple myeloma (NDMM) patients in the first affiliated hospital of Soochow University from September 28, 2012 to July 18, 2105. The serum free light chain levels were measured and κ/λ ratios were calculated, so we could analyze the roles of sFLCR in the diagnosis and prognosis of newly diagnosed multiple myeloma (NDMM) patients.

RESULTS

It was 85.5% (70/82) positive of M protein by serum protein electrophoresis (SFE) and 93.9%(77/82) by serum immunofixation electrophoresis (IFE). Both sFLC and sFLCR abnormalities were 96.3% (79/82). The estimated 40-months overall survival was 87% for the high free light chain ratio group (sFLCR ≥100 or≤0.01) and 61% for the low free light chain ratio group (0.01

CONCLUSION

sFLC assay is much more sensitive than the common methods used, such as SPE and IFE for the diagnosis of MM. The patients with significantly abnormal sFLCR have more tumor burden, higher aggressive progression, and adverse prognosis. Compared with the patients who have normal renal function, the patients with renal insufficiency acquire the same effect after receiving reasonable treatment actively.

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Key Words

• 血清游离轻链比率
• 多发性骨髓瘤
• 诊断
• 预后
• free light chain ratio
• muliple myeloma
• diagnosis
• prognosis

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MESH Headings

• Bone Marrow Cells
• Humans
• Immunoglobulin Light Chains/blood
• In Situ Hybridization, Fluorescence
• Multiple Myeloma/blood
• Multiple Myeloma/diagnosis
• Myeloma Proteins/chemistry
• Prognosis
• Renal Insufficiency/complications
• Retrospective Studies

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Affiliation(s)

P F Wang First Affiliated Hospital of Soochow University, Jiangsu Institute of Hematology, Key Laboratory of thrombosis and hemostasis of Ministry of health , Hematology Collaborative Innovation Center , Suzhou 215006, China
Y Xu
S Yan
Y Yao
H F Zheng
L Ma
S Jin
Y Xu
F R Gong
J Z Zhou
H R Chang
C C Fu

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Prognostic impact of serial measurements of serum-free light chain assay throughout the course of newly diagnosed multiple myeloma treated with bortezomib-based regimens

We retrospectively investigated the role of serial serum-free light chain (sFLC) evaluations in 150 multiple myeloma (MM) patients treated with first-line bortezomib-based regimens. Baseline sFLC ratio (sFLCR) identified three groups of patients - normal, lightly abnormal (<100), and highly abnormal (≥100) - with different progression-free survival (PFS: 3-year estimate 72% versus 61% versus 44%, respectively, p = 0.03). Moreover, the achievement of a normal sFLCR correlated with extended PFS (49 versus 17 months, p < 0.0001) and overall survival (75 versus 43 months, p < 0.0001) as compared with abnormal sFLCR, a gain maintained in a multivariate analysis for PFS. At relapse, a high sFLCR was associated with earlier start of salvage therapy compared with sFLCR <100 (3-month probability: 89% versus 64%, p = 0.0426). In 20% of patients, sFLC escape preceded the conventional relapse by a median of 3.8 months. Our results highlight the role of sFLC assay in the prognosis and follow-up of MM.

Challenges of measuring monoclonal proteins in serum

The measurement of monoclonal protein (M-protein) is vital for stratifying risk and following individuals with a variety of monoclonal gammopathies. Direct measurement of the M-protein spike by electrophoresis and immunochemical measurements of specific isotypes or free light chains pairs has provided useful information about the quantity of M-protein. Nonetheless, both traditional electrophoresis and immunochemical methods give poor quantification with M-proteins smaller than 10 g/L (1 g/dL) when in the presence of polyclonal immunoglobulins that co-migrate with the M-protein. In addition, measurements by electrophoresis of M-proteins migrating in the β- and α-regions are contaminated by normal serum proteins in those regions. The most precise electrophoretic method to date for quantification involves exclusion of the polyclonal immunoglobulins by using the tangent skimming method on electropherograms, which provides a 10-fold improvement in precision. So far, however, tangent measurements are limited to γ migrating M-proteins. Another way to improve M-protein measurements is the use of capillary electrophoresis (CE). With CE, one can employ immunosubtraction to select a region of interest in the β region thereby excluding much of the normal proteins from the M-protein measurement. Recent development of an immunochemical method distinguishing heavy/light chain pairs (separately measuring IgGK and IgGL, IgAK and IgAL, and IgMK and IgML) provides measurements that could exclude polyclonal contaminants of the same heavy chain with the uninvolved light chain type. Yet, even heavy/light results contain an immeasurable quantity of polyclonal heavy/light chains of the involved isotype. Finally, use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) looms on the horizon as a means to provide more consistent and sensitive measurements of M-proteins.

Serum Free Light Chain Assessment Early After Stem Cell Transplantation as a Prognostic Factor in Multiple Myeloma

BACKGROUND

Multiple myeloma is an incurable cancer commonly treated with stem cell transplantation (SCT). Response is traditionally evaluated 100 days after SCT, both to allow for hematopoietic reconstitution and due to immunoglobulins' long half-lives. Free light chains (FLC) have significantly shorter half-lives and may provide evidence of response or treatment failure earlier after SCT.

PATIENTS AND METHODS

We retrospectively studied 83 consecutive patients with multiple myeloma who underwent SCT and found 69 who had FLC measured 30 or 60 days after SCT. Using conventional FLC response criteria, we considered a patient to be at high risk for early relapse if he or she failed to experience a partial response by day 30 or 60.

RESULTS

After a median overall follow-up of only 335 days, these high-risk patients had significantly shorter progression-free survival (median, 98 vs. 335 days, P = .001) and overall survival (366 days vs. median not reached, P = .016).

CONCLUSION

Early FLC assessment either 1 or 2 months after SCT using standard FLC response criteria was able to identify a subset of patients at high risk of early relapse, and these patients may benefit from earlier interventions.

Utility of serum free light chain measurements in multiple myeloma patients not achieving complete response to therapy

Normalization of the serum free light chain ratio (FLCr) with the absence of bone marrow monoclonal plasma cells following achievement of a complete response (CR) to therapy denotes a stringent CR in multiple myeloma (MM), and is associated with improved overall survival (OS). However, its value in patients achieving <CR is not clear. We hypothesized that patients achieving a normalization of FLCr with initial therapy of MM will have an improved outcome, even in the absence of a CR. We retrospectively evaluated 449 patients with newly-diagnosed MM with measurable disease at baseline, who did not achieve a CR with initial therapy. One hundred fifty three patients (34%) had a normal FLCr while 296 (66%) had an abnormal ratio. Patients with a normal FLCr had a longer progression-free survival (PFS) (29 vs. 16 months, P <.001) and OS (91 vs. 58 months, P <.001). Normalization of FLCr retained its prognostic value in a multivariable model. Our results suggest an important role for sFLC measurement in disease monitoring even in patients who achieve only a partial response to therapy. Obtaining a normal FLCr confers a favorable prognosis independent from other factors, supporting the inclusion of sFLC in all levels of response criteria.

Serum free light chain response after 2 courses of induction chemotherapy predicts prognosis in myeloma patients

BACKGROUND

The aim of this study was to investigate the prognostic effect of serum free light chain (sFLC) response after 2 cycles of first-line chemotherapy (CT) in multiple myeloma (MM) patients.

MATERIALS AND METHODS

The data of 78 newly diagnosed MM patients who had sFLC levels at diagnosis and after 2 cycles of first-line CT were included in the study. The prognostic effect of sFLCs were evaluated with normalization of sFLC κ/λ ratio after 2 cycles of CT and involved/uninvolved (i/u) sFLCs.

RESULTS

At the end of follow-up the probability of overall survival (OS) was 95.7% versus 68.5% in patients with and without normalized sFLC κ/λ ratio, respectively (P = .072). The probability of OS with i/u sFLC assessment was 97.4% versus 55.8% with regard to i/u sFLC ≤ 10 and > 10, respectively (P = .001). In univariate and multivariate analysis including sFLC ratio, age, sex, and International Staging System, i/u sFLC ratio > 10 after 2 cycles of CT was identified as an independent risk factor for OS (P = .015; hazard ratio [HR], 13.2; 95% confidence interval [CI], 1.668-104.65 vs. P = .011; HR, 15.17; 95% CI, 1.85-123.89).

CONCLUSION

Early response assessment in terms of sFLC after 2 courses of induction CT seems to have a prognostic effect in MM patients. The methodology and timing of the evaluation based on sFLCs needs to be validated in prospective studies.

Autologous stem cell transplantation for multiple myeloma: identification of prognostic factors

INTRODUCTION

The purpose of this study was to evaluate the effect of prognostic factors on the outcome of patients with MM after ASCT.

PATIENTS AND METHODS

We analyzed results of 170 consecutive patients (121 male and 49 female) of MM who underwent ASCT. Patients' median age was 52 years (range, 26-68 years). High dose melphalan (200 mg/m(2)) was used for conditioning. One hundred thirty-two patients (77.6%) had evidence of chemosensitive disease before transplant. Response was assessed using European Group for Blood and Bone Marrow Transplantation criteria.

RESULTS

Post ASCT 44.7% of patients achieved CR, 24.7% had very good partial response (VGPR), and 21.2% had partial response (PR). Presence of pretransplant chemosensitive disease (CR, VGPR, and PR) and transplant within 12 months of diagnosis for years before 2006 were associated with higher response rates on multivariate analysis. At a median follow-up of 84 months, median overall (OS) and event-free survival (EFS) is 85.5 and 41 months, respectively. Estimated OS and EFS at 60 months is 62 ± 0.04% and 41 ± 0.04%, respectively. Patients who responded to transplant (CR, VGPR, and PR) had a longer OS (P < .001) and EFS (P < .001). Additionally, patients who achieved CR post transplant had a longer OS (P < .001) and EFS (P < .001). Patients who received novel agents for induction pretransplant had a longer OS (P < .001) and EFS (P < .002).

CONCLUSION

Outcome after ASCT is better for myeloma patients with pretransplant chemosensitive disease and those who achieve CR after transplant.

Serial measurement of free light chain detects poor response to therapy early in three patients with multiple myeloma who have measurable M-proteins

Free light chain (FLC) assays are important in the diagnosis and monitoring of patients with multiple myeloma (MM). Serum FLC concentrations also correlate with disease course in the majority of MM patients and have been incorporated into the new response criteria. Although baseline values of FLC are prognostic in newly diagnosed MM, serial measurement of serum FLC does not appear to be of greater value in patients who have measurable M-proteins by electrophoresis. We examined the kinetics of serum FLC in six patients with newly diagnosed MM during treatment with high-dose dexamethasone (HD-DEX) and bortezomib and dexamethasone. In some cases, the involved serum FLC increased in the latter part of each chemotherapy cycle before the start of the next cycle, especially in HD-DEX, suggesting that the response to these agents may be insufficient for induction therapy for MM. Earlier disease assessment by serum FLC assays may be of value in detecting poorly responding patients who require alternative forms of therapy.