Intact Immunoglobulin Multiple Myeloma Research Articles

The Current Role of the Heavy/Light Chain Assay in the Diagnosis, Prognosis and Monitoring of Multiple Myeloma: An Evidence-Based Approach.

Despite tremendous progress being made in recent years, multiple myeloma (MM) remains a challenging disease. The laboratory plays a critical role in the overall management of patients. The diagnosis, prognosis, clinical monitoring and evaluation of the response are key moments in the clinical care process. Conventional laboratory methods have been and continue to be the basis of laboratory testing in monoclonal gammopathies, along with the serum free light chain test. However, more accurate methods are needed to achieve new and more stringent clinical goals. The heavy/light chain assay is a relatively new test which can overcome some of the limitations of the conventional methods for the evaluation of intact immunoglobulin MM patients. Here, we report an update of the evidence accumulated in recent years on this method regarding its use in MM.

Quantification of measurable residual disease in patients with multiple myeloma based on the IMWG response criteria

Stringent complete response (sCR) is defined as a deeper response than complete response (CR) in multiple myeloma. Whether achieving sCR correlates with better survival remains controversial. We evaluated the outcomes in patients with intact immunoglobulin multiple myeloma (IIMM) and light chain multiple myeloma (LCMM) who achieved a very good partial response (VGPR) or better. Multicolour flow cytometry was used to assess the depth of response. LCMM patients with sCR had significantly lower measurable residual disease (MRD) levels than those with CR (median MRD: 7.9 × 10–4 vs. 5.6 × 10–5, P < 0.01). Nonetheless, no significant difference was observed in MRD levels across the responses in groups of patients with IIMM (VGPR vs. CR: 3.5 × 10–4 vs. 7.0 × 10–5, P = 0.07; CR vs. sCR: 7.0 × 10–5 vs. 5.4 × 10–5, P = 0.81. In accordance with MRD levels, the median overall survival of patients with sCR was significantly longer (sCR, CR, VGPR; not reached, 41 months, and 58 months, respectively; VGPR vs. CR, P = 0.83; CR vs. sCR, P = 0.04) in LCMM, but not in IIMM (sCR, CR, VGPR; not reached, 41 months, and not reached, respectively; VGPR vs. CR, P = 0.59; CR vs. sCR; P = 0.10). Our results show that sCR represents a deeper response that correlates with longer survival in patients with LCMM, but not IIMM.

Comparison of Residual Neoplastic Plasma Cell Number Using Multicolor Flow Cytometry and Various Stages of International Myeloma Working Group-Defined Responses in Patients with Multiple Myeloma

【Introduction】Urine and serum immunofixation electrophoresis (IFE) and free light chain (FLC) are used for measuring paraprotein levels produced by neoplastic plasma cells and are widely accepted as standard tests for diagnosis and monitoring of multiple myeloma (MM). Treatment response criteria defined by the International Myeloma Working Group (IMWG) largely relies on the decrease in paraprotein levels of intact immunoglobulin with or without serum FLC. However, the paraprotein levels vary widely between patients and even in the same patient during the course of the disease. Therefore, considerable discrepancy often exists between the extents of decrease in neoplastic tumour cell burden and paraprotein levels in response to chemotherapy. We retrospectively compared the bone marrow plasma cell (BM-PC) levels using 6- to 8-color flow cytometry (FCM) with various levels of IMWG-defined responses after treating patients with MM.【Methods】We included patients with MM (light chain only multiple myeloma (LCMM), n =35 ; intact immunoglobulin multiple myeloma (IIMM), n =115 ) who were treated at Kameda Medical Center, Japan and Kanazawa University Hospital, Japan, between April 2007 and June 2017. Among them, 130 patients (LCMM; n=35 , IIMM; n=95 ) who achieved partial response (PR) or better response were selected on the basis of the co-availability of serum and urine test data, FLC data, and multicolor flow cytometry (MFC)-generated BM-PC quantitation data. MFC-mediated assessment of BM-PCs was performed during diagnosis and when each IMWG-defined treatment response was obtained. The residual BM-PC level was compared with the IMWG-defined responses using Kruskal-Wallis analysis. Oligosecretary and non-secretary myeloma were excluded from this study. This study conformed to the principles of the Declaration of Helsinki.【Result】Complete data set of IFE, FLC, and MFC during diagnosis, PR, very good partial response (VGPR), complete response (CR), and stringent CR (sCR) were available in 37, 58, 10, and 50 samples in IIMM and in 4, 21, 15, and 21 samples in LCMM. Mean BM-PCs during diagnosis in IIMM and LCMM was 2.1 x 10-1 and 2.2 x 10-1, respectively. In patients with IIMM, mean residual BM-PCs at PR, VGPR, CR, and sCR in IIMM were 1.8 × 10-2 (range: 1.4 × 10-5-7.5 × 10-2), 2.0 × 10-3 (range: 1.4 × 10-5-2.9 × 10-2), 4.4 × 10-4 (range: 2.1 × 10-5-2.0 × 10-3), and 4.8 × 10-4 (range: 2.0 × 10-6-5.3 × 10-3), respectively. Although significant difference in residual BM-PC levels was observed between PR vs. VGPR (P < 0.01), there were no statistically significant difference between VGPR vs. CR (P = 0.08) and CR vs. sCR (P = 0.9). Of note, 58% patients had residual MM cells ≥ 10-4 even when they achieved sCR. The amount of involved intact immunoglobulin at diagnosis was significantly higher in these patients than those who achieved residual MM cells <10-4 (mean: 5206.1 vs. 3954.7 p = 0.04).In patients with LCMM, mean residual BM-PCs cells at PR, VGPR, CR, and sCR were 3.5 × 10-2 (range: 5.1 × 10-3-7.7 × 10-2), 8.9 × 10-3 (range: 4.0 × 10-4-8.9 × 10-2), 2.0 × 10-3 (range: 4.0 × 10-5-1.0 × 10-2), and 1.1 × 10-4 (range: 2.0 × 10-6-7.0 × 10-4), respectively. Significant difference in the amount of residual BM-PC was only observed between CR and sCR, but not in PR vs. VGPR and VGPR vs. CR (PR vs. VGPR: p = 0.08, VGPR vs. CR: p = 0.08, CR vs. sCR: p = 0.03). Normal FLC ratio was highly predictive of lower residual BM-PCs (> 10-4) in LCMM. (Figure 1)Figure 2 shows the proportion of residual BM-PCs at various IMWG responses. The percentages of samples with residual BM-PCs at the levels of ≥ 10-3, 10-3 > - ≥ 10-4 , and < 10-4 in IIMM were 86.8% (n = 32/37), 7.8% (n = 3/37), and 5.2% (n = 2/37) for PR, 31.0% (n = 18/58), 56.8% (n = 33/58), and 12.0% (n = 7/58) for VGPR, 20% (n = 2/10), 40% (n = 4/10), and 40% (n = 4/10) for CR, and 12% (n = 6/50), 46% (n = 23/50), and 42% (n = 21/50) for sCR, respectively. In the case of LCMM, these figures were 100% (n = 4/4), 0% (n = 0/4), and 0% (n = 0/4) for PR, 66.6% (n = 14/21), 33.3% (n = 7/21), and 0% (n = 0/21) for VGPR, 20% (n = 3/15), 66.6% (n = 10/15), and 13.3% (n = 2/15) for CR, and 0% (n = 0/21), 23.8% (n = 5/21), and 76.1% (n = 16/21) for sCR, respectively.【Conclusion】The depth of residual BM-PCs response did not parallel that of IMWG response, and ~20% patients with CR had high level of residual BM-PCs (≥ 10-3). Although paraprotein-based assessment is feasible for disease monitoring in MM, our data indicates that response to treatment could be better assessed by BM-PC. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Normalization of the Serum Free Light Chain Ratio in Patients with Intact Immunoglobulin Multiple Myeloma Who Achieve Less Than Complete Response

BackgroundNormalization of the serum free light chain ratio (rFLC) following achievement of complete response (CR) denotes stringent CR in multiple myeloma (MM) and is associated with favorable prognosis. In contrast, the clinical significance of this phenomenon in patients not achieving CR has not been energetically studied. Only a few studies have reported better progression free survival (PFS) and overall survival (OS) in patients who achieved normalization of the rFLC at their best response than in those who did not. As monoclonal intact immunoglobulin (Ig) and monoclonal FLC are independent biomarkers for the neoplastic plasma cell burden in intact immunoglobulin MM (IIMM), it is not clear whether patients who failed to achieve CR but normalized the rFLC also had improved outcomes. Here, we retrospectively analyzed the prognostic significance of normalization of the rFLC in IIMM patients who did not achieve CR.Patients and methodsConsecutive patients with IIMM diagnosed and treated at the Kameda Medical Center from Jun 2007 to April 2017 were identified. IMWG response criteria were used to assess response. We excluded patients with negative immunofixation for monoclonal M-protein in the serum or urine at diagnosis and those who achieved CR. The FLC assay (FREELITE, The Binding Site, Birmingham, UK) was performed at least monthly as a part of routine clinical management. The following ranges were used for normal FLC values: κ FLC, 0.33-1.94 mg/dL; λ FLC, 0.57-2.63 mg/dL; and rFLC, 0.26-1.65.ResultsThere were 239 patients diagnosed with symptomatic MM, including 191 patients with IIMM and 48 patients with light chain MM (LCMM). Among 191 patients with IIMM, 78 achieved CR by chemotherapy; the remaining 113 patients were included in this analysis. No patient with LCMM achieving less than CR (n = 15) obtained normalization of rFLC during the whole treatment. The median observation period was 21.9 months (m) [range, 0.2-118.9 m] and the median age was 77.0 yr (range, 43.8-90.7 yr). Sixty-four of the 113 patients (56.6%) obtained a normal rFLC during the course of treatment. Patients who achieved a normal rFLC were significantly younger (median age, 75.3 vs 79.2 yr, P = 0.014), more frequently received autologous stem cell transplantation (15.6% vs 0%, P = 0.005), and had better response [very good partial response (VGPR) rate: 57.8% vs 22.4%, P < 0.001] than those who did not. No significant difference was seen between patients with and without normalization of the rFLC with regard to sex, heavy- or light-chain type, ISS category, revised ISS category, albumin, β2 microglobulin, or creatinine levels, hemoglobin concentration, lactate dehydrogenase abnormality, induction regimen, or administration of maintenance therapy. Patients with a normal rFLC had significantly longer PFS and OS than those without on univariate analysis (median PFS, 24.2 vs 6.6 m, P = 0.001; median OS, 59.6 vs 20.2 m, P < 0.001). Normalization of the rFLC retained its prognostic significance for both PFS and OS on multivariate analysis (both P < 0.001). We further examined the impact of achievement of a normal rFLC on PFS and OS in patients with a high or low baseline rFLC. Using receiver operating characteristic curve analysis, the optimal cutoff was 69.8; patients were divided into two groups based on the cutoff. As expected, patients with a higher baseline rFLC who achieved a normal rFLC had longer PFS and OS (median PFS, 29.7 vs 4.3 m, P < 0.001; median OS, 93.6 vs 15.8 m, P < 0.001), but those with a lower baseline rFLC did not (median PFS, 21.4 vs 7.1 m, P = 0.484; median OS, 53.9 vs 34.9 m, P = 0.120). In addition, patients with a lower baseline rFLC were more likely to achieve normal rFLC than those with a higher baseline rFLC, although the difference was not statistically significant (P = 0.074).ConclusionThis study demonstrated that achieving normalization of the rFLC during the course of treatment is robustly predictive for both PFS and OS in patients with IIMM who do not achieve CR. As monoclonal FLC is secreted independently of monoclonal intact Ig from neoplastic plasma cells, normalization of the rFLC also confers improved prognosis of patients with IIMM who had high levels of rFLC. These data indicate that serial measurement of FLC at all levels of response may be a valuable tool for accurate prognostication in IIMM even when achieving only VGPR or worse response to therapy. [Display omitted] DisclosuresKitadate:Fujimoto: Research Funding; Novartis: Research Funding; Kyowa Kirin: Research Funding; Otsuka: Research Funding; Toyama kagaku: Research Funding; Eisai: Research Funding; Asahi Kasei: Research Funding; Chugai: Research Funding; Pfizer: Research Funding.

Serum Free Light Chain Assay Measurement at Disease Relapse for Prognostication in Patients with Multiple Myeloma in the Novel Agent Era

BackgroundMonoclonal serum free light chains (sFLC) are detected in patients with B-cell proliferative disorders including multiple myeloma (MM) at diagnosis and disease relapse. Several previous studies demonstrated prognostic impact of the involved and uninvolved sFLC ratio (rFLC) in patients with newly diagnosed MM, patients with monoclonal gammopathy with undetermined significance, and smoldering MM. However, the prognostic impact of rFLC and differences between involved and uninvolved FLCs (dFLC) at the time of disease relapse have not been fully elucidated.Patients and methodsWe identified consecutive patients with symptomatic MM, diagnosed and treated at Kameda Medical Center from January 2006 to April 2017. Patients who experienced initial relapse during June 2007 (the time where we began to routinely measure sFLC in MM patients) to April 2017 were identified. We reviewed background and outcome data from the electronic record. IMWG response criteria were used for assessing response and disease progression. rFLC was defined as involved FLC (iFLC) level divided by uninvolved FLC (uFLC) level. dFLC was calculated by subtracting uFLC from iFLC. Time to second progression (2nd TTP) and overall survival after first relapse (OS after 1st relapse) were defined as the time from the date of first progression to the date of second progression and death from any cause, respectively. Receiver operating characteristic (ROC) analysis determined optimal cutoff levels of rFLC and dFLC. We divided patients into high or low rFLC or dFLC, according to these cutoff levels. To clarify the relationship between rFLC increase at relapse and subsequent prognosis, patients were divided into 4 groups according to the rFLC levels: patients with rFLC >0 and ≤10, >10 and ≤100, >100 and ≤1000, and >1000.ResultsThere were 240 patients diagnosed with symptomatic MM. Among them, 124 patients experienced disease relapse at least once during the observation period. Of the 124 patients, 97 were classified as having intact immunoglobulin MM and 27 had light chain MM. Median observation period from first relapse and age at first relapse of the 124 patients was 19.8 (range: 0.7 - 111.4) months (m) and 73.7 (range: 46.7 - 90.1) years, respectively. All patients received novel induction therapy agents. Using ROC analysis, we determined the optimal cutoff of rFLC and dFLC for predicting highest risk of second relapse within 1 year of first relapse as 19.7 and 122.9 mg/L, respectively. Patients with higher rFLC (n=57) had significantly shorter 2nd TTP and OS after 1st relapse than those with lower rFLC (n=67) (median 2nd TTP, 4.1 vs 24.7 m; P<0.001, and median OS after 1st relapse, 19.3 vs 42.7 m; P<0.001, respectively). Patients with higher dFLC (n=57) had significantly shorter 2nd TTP and OS after 1st relapse than those with lower rFLC (n=67) (median 2nd TTP, 5.5 vs 20.5 m; P<0.001, median OS after 1st relapse, 19.1 vs 42.7 m; P<0.001, respectively). Both 2nd TTP and OS after 1st relapse were significantly shorter when associated with increased rFLC levels. The median survival of patients with rFLC >0 and ≤10 (n=57), >10 and ≤100 (n=30), >100 and ≤1000 (n=22), and >1000 (n=15) were 30.5, 9.9, 4.7 and 1.6 m, respectively for 2nd TTP and 72.6, 33.6, 24.9 and 14.7 m respectively for OS after 1st relapse (both, P<0.001), whereas no significant difference was detected among the four risk groups of patients for age at first relapse, international staging system (ISS), revised ISS, the level of albumin, beta-2 microglobulin, creatinin, hemoglobin, lactate dehydrogenase abnormality, high-risk cytogenetic abnormality, or chemotherapy after first relapse.ConclusionAt disease relapse, both rFLC and dFLC clearly identified different patient risk groups for subsequent prognosis. High rFLC and dFLC at relapse related to shorter 2nd TTP and OS after 1st relapse. Our data indicate that serial measurement of serum FLC assays may predict prognosis after relapse in patients with MM who receive novel agents and experience disease progression. [Display omitted] DisclosuresKitadate:Kyowa Kirin: Research Funding; Eisai: Research Funding; Asahi Kasei: Research Funding; Pfizer: Research Funding; Otsuka: Research Funding; Chugai: Research Funding; Novartis: Research Funding; Fujimoto: Research Funding; Toyama kagaku: Research Funding.

HLC Pair Suppression as a Risk Factor for Bacterial Bloodstream Infections and Early Mortality in Newly Diagnosed Intact Immunoglobulin Multiple Myeloma Patients.

Despite the outstanding progresses in Multiple Myeloma treatment options in the last decades, it remains an incurable disease nowadays. Infectious events are a complication due to an impaired immune system associated with MM, sometimes a life-threatening one, particularly on the first months after the diagnosis. Both the underlying disease and treatment can contribute to the infection risk, so a biomarker that assess this risk could be highly relevant for a more tailored management of the patient. The measurement of the heavy+light chain (HLC) pairs of immunoglobulins in serum allows the quantification of both the monoclonal component and the non-monoclonal immunoglobulin of the same isotype. This approach has demonstrated high sensitivity for the detection of the clonality and prognostic value for MM. HLC pair suppression itself has prognostic power and it has been proposed to be a reflection of the immune system’ attempt to control the tumor. In this study we evaluated the impact of the HLC pair suppression on the rate of bloodstream infections (BSI) and early death in 115 newly diagnosed MM patients. Twenty-one percent of the patients suffered a BSI in the first 6 months after diagnosis, of which 58% died within this period, accounting to 67% of the early deaths in global and highlighting the major impact of infections on MM patients in a “real world” setting. Severe HLC pair suppression identified patients with a higher risk of early BSI (HR: 6,97, p=0,009), and extreme HLC pair suppression together with BSI event and age >65 were independent risk factors for early death (p<0,001). Based on these factors, a stratification model was generated to allow identify patients at a higher risk of early death and poorer OS, with an apparently better performance than the ISS on the early death context. In conclusion, HLC pair suppression associates with both a higher risk of life-threatening early infection and early death in newly diagnosed MM patients. Patients older than 65 with extreme HLC pair suppression and BSI are at a high risk of early death, and thus patients presenting with these criteria have a very adverse prognosis.

Comparison of Sebia Free Light Chain Assay With Freelite Assay for the Clinical Management of Diagnosis, Response, and Relapse Assessment in Multiple Myeloma

BackgroundSerum free light chain (FLC) measurement has become an important marker for the management of multiple myeloma (MM). However, several analytical challenges remain unresolved. We compared the clinical performances of the Sebia FLC assay in MM to the Freelite assay. Patients and MethodsA total of 177 patients from the IFM DFCI 2009 trial were enrolled onto this study, with a total of 368 samples analyzed. At baseline, concordance of the involved to noninvolved FLC ratio (iFLC/niFLC) was evaluated. During therapy, comparison of the disease response assessments according to International Myeloma Working Group criteria was performed. ResultsCompared to Freelite, the Sebia FLC assay demonstrated lower results, with a proportional bias with increased values. We demonstrated that the Sebia equivalent of the iFLC/niFLC ratio of 100 was 16. During follow-up, agreement in response assessment was moderate (for light chains MM) to good (for intact immunoglobulin MM). In the context of relapse, the concordance was moderate, but longitudinal follow-up showed a similar kinetics. ConclusionThe Sebia FLC assay provides inequivalent absolute results from the Freelite assay. Despite lower absolute FLC values, the kinetics of response and relapse is exactly the same. As with other FLC assays available, follow-up of MM with the same method is advisable.

Quantification of bone-marrow plasma cell levels using various International Myeloma Working Group response criteria in patients with multiple myeloma.

We examined the association of residual bone-marrow plasma cells (PCs) and International Myeloma Working Group (IMWG) response assessment in light-chain-only multiple myeloma (LCMM) and intact immunoglobulin multiple myeloma (IIMM) using multicolour flow cytometry (MFC). We identify considerable differences in bone-marrow neoplastic PC levels between IIMM and LCMM for the same IMWG response categories. Furthermore, even in the same IMWG response category, residual neoplastic PC levels differed considerably over a logarithmic scale range However, normalization of the free light-chain ratio is associated with deeper response (< 10-4) in LCMM, but not in IIMM. Our observations highlight the importance of quantifying BM PC by MFC for response assessment, especially for relapsed disease when there is suspected discrepancy in paraprotein levels and disease progression.

Heavy/light chain assay as a biomarker for diagnosis and follow-up of multiple myeloma

BackgroundThe heavy-light chain (HLC) assay enables the accurate measurement of each isotype-specific heavy and light chain (i.e., IgGĸ, IgGλ, IgAĸ, and IgAλ) and the derivation of an HLC-pair ratio. However, to date, only limited data have validated the usefulness of serial HLC measurements in the routine follow-up of intact immunoglobulin multiple myeloma (MM) patients. MethodsA total of 36 diagnostic and 671 post-treatment sera from 115 IgG and 61 IgA MM patients were assessed with capillary zone electrophoresis, immunosubtraction electrophoresis, total immunoglobulin measurement, free light chain, and HLC assay. The correlations between M-protein levels and the HLC and FLC assay-derived parameters were examined and the clinical significance of the biomarkers was evaluated according to patients' status. ResultsInvolved HLC (iHLC) was the best biomarker correlating with M-protein concentration in both IgG and IgA MM, and could provide a surrogate marker substituting M-protein levels to follow the course of the disease, especially in β-migrating IgA M-proteins. The distribution of iHLC values as well as HLC-pair ratios (rHLC) yielded significantly different results among the various response categories in both IgG and IgA MM. In addition, we detected 2 cases in which an abnormal rHLC in a stringent complete remission (sCR) sample was a marker of early non-symptomatic relapse. ConclusionIn this study of a cohort of 176 patients in a routine clinical setting, we have provided evidence of the clinical utility of real world HLC assays for the identification of M-proteins and to monitor M-proteins with an emphasis on IgA monoclonal gammopathies.

Impact of Normalized Free Light Chain Ratio for Assessment of Monoclonal Protein in Patients with Light Chain Only and Oligosecretory Myeloma

Background: Monitoring of serum free light chain (sFLC) ratio after treatment in multiple myeloma (MM) patients is valuable for assessing monoclonal component of free light chain (FLC). However, the recent International Myeloma Working Group guidelines did not recommend replacing 24-hour urine analysis with FLC analysis in diagnosis or response assessment of MM, and previous studies indicated discordance between urine analysis and sFLC levels in light chain-only MM (LCMM). This is clinically relevant because sFLC normalization was considered a surrogate for improved outcome in both LCMM and intact immunoglobulin MM (IIMM). The clinical impact of FLC ratio normalization on detection of monoclonal component may differ between LCMM or oligosecretory myeloma (OSMM) and IIMM. This study explored the utility of sFLC ratio as a surrogate for residual clonal monoclonal component compared with 24-hour urine immunofixation electrophoresis (uIFx) after treatment. We evaluated the impact of normalization of sFLC ratio in patients with LCMM/OSMM that obtained very good partial response (VGPR), complete response (CR), and immunophenotypic CR (iCR; sIFx/uIF negative plus ≤ 10-4 clonal PCs) determined by multicolor flow cytometry (MFC).Methods: We included 176 patients (51 with LCMM and OSMM, 125 with IIMM) treated between April 2006 and January 2016 at Kameda Medical Center, Japan. Immunoglobulin levels in serum and urine samples were examined by serum protein electrophoresis (SPEP), serum immunofixation electrophoresis (sIFx), urine protein electrophoresis (UPEP), uIFx, and sFLC for response assessment. Minimal residual disease (MRD) assessments after treatment were performed by 6-color MFC and the results were compared to other tests of monoclonal components, including SPEP, UPEP, sIFx, uIFx, and FLC. Agreement between sFLC normalization and MRD by MFC was assessed using kappa statistic. Disease response was evaluated using IMWG criteria. sFLC was measured by Fleelite® assay (The Binding Site Group Ltd.). Reference ranges for sFLC have been previously published. Statistical analyses were performed with EZR, which is a graphical user interface for R ver. 3.2.1.Ethical considerations: This study was approved by the local ethics committee and conducted in accordance with the Declaration of Helsinki and Good Clinical Practice Guidelines.Results: All of 51 LCMM/OSMM patients (100%) and 95 of the 125 IIMM patients (72%) had measurable and abnormal involved sFLC (≥ 100 mg/L) and positive uIFx at presentation. VGPR, CR, and iCR were obtained in 31 (61%), 25 (49%), and 14 (27%) patients with LCMM/OSMM, respectively, and normalization of sFLC ratio at VGPR, CR and iCR was seen in 1/31 (3%), 13/25 (48%), and 8/14 (57%) of these patients, respectively. Among the LCMM/OSMM patients with iCR, 4 patients obtained deeper iCR (≤ 10-5 clonal PCs) and all of them had normal sFLC ratio, while sFLC ratio remained abnormal in the rest of 10 iCR patients that did not achieve deeper iCR. In IIMM patients, VGPR, CR, and iCR were obtained in 78 (61%), 52 (42%), and 20 (16%) patients, respectively. In contrast to the LCMM/OSMM patients, normalization of the sFLC ratio at VGPR, CR, and iCR was seen in 52/78 (67%), 39/52 (75%), and 17/20 (85%) of IIMM patients, respectively. Thirteen of the 14 IIMM patients (93%) that obtained deeper iCR had normal sFLC ratio. Among the patients with IIMM, percentage of patients with normalized sFLC ratio did not differ between the response groups (p=0.11), while it was significantly different in LCMM/OSMM patients (p<0.001) (Figure 1). These observations indicated that the normalization of sFLC ratio is significantly associated with deeper response in LCMM/OSMM patients, but not in IIMM patients.Conclusions: Our observations indicated that sFLC test has greater sensitivity than urine immunofixation for detection of the monoclonal component of sFLC, especially in patients with LCMM/OSMM. In addition, we also showed that normalization of sFLC ratio is correlated with the depth of response assessed by MFC in patients with LCMM/OSMM, but not in IIMM patients. These findings suggest that FLC ratio provides greater sensitivity for residual disease monitoring than uPEP or uIFx in patients with LCMM and OSMM, and therefore could be considered as an alternative to urine analysis for monitoring of LCMM/OSMM patients. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Responses Assigned Using Heavy+Light Chain Assessments Have Better Clinical Correlation with Outcome Than Those Using Current IMWG Criteria for Multiple Myeloma

Introduction: Stratification of multiple myeloma patient responses by reductions in monoclonal component is based upon reliable, historic outcome data. With the introduction of novel agents, a greater number of patients are achieving hitherto unthought-of responses, with many expecting to meet the requirement for VGPR or greater. Multiple factors can impact the quantification and assessment of response in patients achieving deep responses including the influence of IgG recycling, accuracy of quantitation against an increasing polyclonal background and the presence of monoclonal immunotherapies. Alternative strategies for monoclonal protein measurement include heavy+light chain (HLC) immunoassays. Here for the first time we compare the consistency of response assignment between the two methods and evaluate the clinical impact of discordance.Methods: Sera from 509 newly diagnosed intact immunoglobulin multiple myeloma (IIMM) patients enrolled onto IFM-2009 trial were available (median age was 59 (range: 33-66) years, follow-up 30 (3-56) months). Two patients arms were treated with RVDx3+ASCT+RVDx2 or RVDx8, followed by 12 months Lenalidomide maintenance. Responses were assigned at the end of consolidation therapy according to IMWG criteria using changes in monoclonal protein concentrations measured by either SPE or dHLC (clonal - non clonal). Complete response (CR) was assigned by either method by the absence of monoclonal protein on IFE or a normal HLC ratio (HLCr), respectively, and <5% BM plasma cells. HLC-pair suppression was defined as levels of the non-clonal HLC (e.g. IgGλ in an IgGκ patient) below the reference range (IgGκ <3.84g/L; IgGλ <1.91g/L; IgAκ <0.57g/L; IgAλ <0.44g/L). Minimal residual disease (MRD) was assessed by 7-color flow cytometry at the end of consolidation therapy.Results: IFE and HLCr concordantly identified clonality in 99% patients. In 463 patients followed until the end of consolidation we found moderate agreement in response assignment between the two tests. HLC gave similar response assignments to electrophoretic tests in patients with poor response (≤PR, 76/96; 79%) or complete response (≥CR, 130/142; 92%). However in patients achieving VGPR there was considerable discordance between methods for response assignment (102/225; 45%). Having identified discordant results for VGPR we sought to assess the clinical accuracy of the responses assigned within this group. Of the 225 patients with standard VGPR, HLC response assignment varied (PR (18/225), VGPR (102/225) and ≥CR (105/225)). Median PFS for patients achieving standard VGPR was 34.5 months; responses by HLC further described these patients into those with poorer PFS (PR, median PFS=21.3 months (95%CI: 9.0-33.7)); VGPR (PFS=28.9 months (95%CI: 25.1-32.6)), and those with improved outcomes (CR, median PFS not reached); p<0.0001 (Figure 1). This suggested that the response assigned by electrophoresis could be refined by HLC analysis. By contrast, responses assigned by electrophoretic methods offered no added clinical value in patients achieving VGPR (log-rank: p=0.724) or ≥CR (log-rank: p=0.402) by HLC assessment. Furthermore, an abnormal HLCr post-consolidation had a greater concordance with MRD+ assessment (78% positive) compared to IFE (51% positive); whereas both a normal HLCr and negative IFE displayed similar agreement with MRD- assessment (88% and 94% negative, respectively).Finally we assessed the clinical impact of recovering polyclonal immunoglobulin levels after consolidation therapy. In 142 patients with complete responses, HLC-pair suppression (n=15, median PFS=35.1 months (95%CI: 20.9-49.2) and severe suppression (n=7, median PFS=22.9 months (95%CI: 16.6-29.2)) were associated with poorer outcomes (p=0.060 and p=0.004, respectively).Conclusions: In patients achieving a poor or exceptional response there was good agreement between HLC and standard response assignment. For patients achieving a VGPR we suggest that HLC response assignment may be beneficial, therefore overall the assessment could be used to augment or replace electrophoresis. The prognostic significance of HLC responses seems to be partly dependent in the patient's ability to recover their immune system, as determined by normalisation of non-clonal HLC levels. [Display omitted] DisclosuresMichallet:Bristol-Myers Squibb: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Astellas Pharma: Consultancy, Honoraria; MSD: Consultancy, Honoraria; Genzyme: Consultancy, Honoraria. Attal:sanofi: Consultancy; janssen: Consultancy, Research Funding; amgen: Consultancy, Research Funding; celgene: Consultancy, Research Funding. Moreau:Novartis: Honoraria; Celgene: Honoraria; Takeda: Honoraria; Janssen: Honoraria, Speakers Bureau; Amgen: Honoraria; Bristol-Myers Squibb: Honoraria. Avet-Loiseau:janssen: Consultancy; sanofi: Consultancy; amgen: Consultancy; celgene: Consultancy.

The Role of Serum Free Light Chain and M-Protein Measurements in Determining Recurrent Disease in Multiple Myeloma After Stem Cell Transplantation

The detection of reoccurrence of multiple myeloma (MM) after stem cell transplant (SCT) is usually carried out by the use of serum and urine protein electrophoresis and immunofixation. We retrospectively studied the utility of serum free light chain assay (sFLC) in a population of post-SCT MM patients and compared it to traditional methods with serum protein electrophroesis (SPEP). We compared the value of sFLC vs SPEP for predicting reoccurrence and for earlier detection. We analyzed consecutive 24MM patients diagnosed between 2004 and 2009, who underwent SCT with concomitant follow-up with sFLC and M-protein from 2004 to 2012. An elevated M-protein was indicated by a level ?0.2g/dL. An abnormal sFLC was indicated by a ?:? ratio >1.65 or 10 mg/dL of sFLC from the baseline. Of the 24 cases, 22 had intact immunoglobulin MM (16 IgG, kappa; 2 IgG lambda; 2 IgA lambda; 2 IgA kappa) and 2 cases had light chain MM. All 24 cases (100%) achieved a complete response or partial response to SCT as defined by the International Myeloma Working Group (IMWG). After SCT, 4 (16.7%) MM patients remained in remission. 12 (50.0%) patients had a recurrence of MM with measurable increases in both sFLC and M-spike, 5 (20.8%) with increase in sFLC only and 3 (12.5%) with increase in M-spike alone. Among the 20 patients with reoccurrence after SCT, 35% had earlier detection of sFLC than M-spike, 10% had M-spike detected before sFLC, 15% had concurrent elevated sFLC and M-spike, 25% had elevated sFLC only, and 15% had elevated M-spike alone. The medium time period for detecting the elevated sFLC or M-spike in patients undergoing reoccurrence after SCT was 3-6 months vs. 6-9 months (p-value: 0.0386; Mann-Whitney one-sided test). Our study concludes that sFLC should be used in conjunction with clinical and other traditional measures for the earliest detection of MM recurrence to ensure that the diagnosis is not missed by using SPEP assay alone.

Can Assessment of Patient Monoclonal Immunoglobulins By Heavy/Light Analysis be Used to Assign Patient Responses Analogous to IMWG Response Criteria?

BackgroundQuantification of monoclonal immunoglobulins in serum is the foundation of IMWG multiple myeloma (MM) response criteria for patients with intact immunoglobulin disease. However, electrophoretic methods for quantifying M-Ig in serum are subject to well documented limitations including inaccuracy at high concentrations (due to dye saturation) and poor sensitivity at low concentrations. Moreover, the methods require skilled interpretation and can be time consuming; however their clinical utility is well established. Recently heavy/light chain (HLC) assays, which quantify kappa and lambda isotypes of intact immunoglobulins have become available. Here we compare responses assigned by the immunoassays to IMWG criteria and evaluate the clinical impact of discordance.MethodsSequential sera, from enrolment to progression, were available for 107 MM patients (59 IgGκ, 29 IgGλ, 12 IgAκ, 7 IgAλ) enrolled onto either the IFM 2009-02 end-stage relapsed or refractory MM or the IFM 2010-02 in del17p and t(4;14) relapsed or refractory MM trials. The inclusion criterion was a measurable intact immunoglobulin MM according to IMWG criteria (M spike ≥ 10 g/L), using serum and/or urine protein electrophoresis. IgA HLC (IgAκ and IgAλ) and IgG HLC (IgGκ and IgGλ) analysis was compared to historic SPEP, IFE, UPEP, uIFE and serum free light chain (sFLC) results (measured using polyclonal antisera based assays). Responses were assigned at approximately 90 days (median 90, range 61-107 days) and at maximum response (if different) according to IMWG criteria using changes in monoclonal protein concentrations measured either by SPEP or dHLC (clonal - non clonal). Complete response was assigned either by the absence of monoclonal protein on IFE or by a normal HLC ratio.ResultsAt the time of enrolment, 87/88 IgG and 17/17 IgA patients had abnormal HLC ratios which were concordant with IFE results, and quantification of the monoclonal protein by dHLC was similar (median (range): 29.2 (2.5-77.5) g/L) and SPEP (30.7 (1.8-66.9) g/L). After 3 months of treatment, responses assigned by HLC/FLC assays showed near-perfect agreement with responses assigned using SPEP and IFE (Weighted Kappa >0.81, p<0.001). Analysing patients with ≥ partial response (PR) or <PR by either method showed 93% concordance. However, univariant Cox regression modelling suggested that the HLC assigned responses were significantly associated with PFS (p=0.05), whereas the IMWG assigned responses were not (p=0.345). Similarly, HLC assigned responses had a slightly better model fit using AIC statistics compared to IMWG assigned response (AIC 374 vs. 378).At maximum response there was near-perfect agreement between the responses assigned using HLC/FLC or SPEP, IFE, UPEP, uIFE (Weighted Kappa >0.81, p<0.001). Changes in dHLC predicted response in 16/39 patients (15 IgG and 1 IgA), achieving ≥PR up to 224 days earlier than SPEP (median 52 days, range 22-224 days). In addition, in 10/79 patients, changes in dHLC indicated relapse up to 77 days (median 56 days range 28-77 days) earlier than standard methods.ConclusionChanges in dHLC can be used in place of SPEP quantification to assign IMWG responses in patients with intact immunoglobulin MM. Minor discordances had an impact on the model fit favouring the HLC assigned response over response assigned using SPE/IFE. Changes in dHLC identified response and relapse earlier than clinically assigned in a number of patients. Considering the small number of patients, we suggest that larger prospective trials be conducted to validate these findings. DisclosuresLeblond:GSK: Consultancy, Honoraria, Speakers Bureau; Janssen: Consultancy, Honoraria, Speakers Bureau; Roche: Consultancy, Honoraria, Other: Travel, Accommodations, Expenses, Speakers Bureau; Mundipharma: Honoraria; Gilead: Consultancy, Honoraria, Speakers Bureau. Snell:The Binding Site Group Ltd: Research Funding. Leleu:Celgene: Honoraria; Janssen: Honoraria; Novartis: Honoraria; BMS: Honoraria; Amgen: Honoraria.

Early Evaluation of Response by Serum Free Light Chain (FLC) and Hevylite (HLC) in Intact Immunoglobulin (iIg) Multiple Myeloma (MM): prediction of outcome

Early Evaluation of Response by Serum Free Light Chain (FLC) and Hevylite (HLC) in Intact Immunoglobulin (iIg) Multiple Myeloma (MM): prediction of outcome

Heavy/light chain specific immunoglobulin ratios provides no additional information than serum proteins electrophoresis and immunofixation for the diagnosis and the follow-up of intact immunoglobulin multiple myeloma patients

BackgroundSerum protein electrophoresis (SPE) and immunofixation electrophoresis (IFE) are used for diagnosis and follow-up of patients with intact immunoglobulin multiple myeloma. However, the numerous limitations of these methods led to the development of a nephelometric immunoassay (Hevylite™) for the specific measurement of serum IgGκ, IgGλ, IgAκ and IgAλ concentrations. MethodsIn this study, we evaluated the correlation between this assay and SPE and IFE in 114 sera of 15 patients (12 IgG and 3 IgA patients) and its impact on the clinical care of patients, especially for diagnosis, for the evaluation of residual disease and for early detection of relapse. ResultsAt inclusion and during follow-up, we found a good correlation between monoclonal immunoglobulin concentrations and SPE (R2=0.902 for IgA and R2=0.915 for IgG) and nephelometric quantification (R2=0.948 for IgA and R2=0.920 for IgG) for the evaluation of monoclonal and polyclonal immunoglobulins. Our results illustrate that the Hevylite™ test is less sensitive than the IFE for detection of residual disease: 5 patients who obtained very good partial response or complete response had normalization of the Hevylite™ ratio while IFE was still positive. A relapse had been detectable with the Hevylite™ ratio 1 to 2 months earlier than with SPE and IFE in 3 patients out of 15, but no recommendations for treating patients with only slight biological relapse are available. ConclusionOur results demonstrate that heavy/light chain specific immunoglobulin ratios provides no additional information than serum proteins electrophoresis and immunofixation for the diagnosis and the follow-up of intact immunoglobulin multiple myeloma patients. We also studied the correlation between the concentration of total immunoglobulin measured by Hevylite™ (sum of Ig’κ + Ig’λ) and nephelometric measurement of total IgG or IgA. For this correlation analysis, all 114 sera were analyzed. The correlation coefficient was R2 = 0.948 for IgA and R2 = 0.920 for IgG.

Immunoglobulin Heavy/Light Chain Measurements Provide Prognostic Information in Multiple Myeloma Patients Undergoing Autologous Stem Cell Transplantation

Introduction. Both reduction in M-protein and reconstitution of the immune system are associated with increased survival in multiple myeloma (MM) patients receiving an autologous stem cell transplant (ASCT). Heavy/light chain (HLC) pair analysis allows discrimination between Igκ and Igλ and as a result allows measurement of both the monoclonal involved and polyclonal uninvolved HLC pair. Abnormal HLC ratios and suppression of the uninvolved HLC pair correlate with shorter overall survival in MM patients. We evaluated HLC analysis for predicting progression free survival in MM patients receiving an ASCT.Methods. We prospectively evaluated 28 intact immunoglobulin MM (IIMM) patients (12 Female, 16 Male; 20 IgG, and 8 IgA; median age: 54 years; range 37-67 years) who received ASCT subsequent to high dose melphalan. Median follow up time from ASCT was 391 days (range: 61-603 days). Patient responses were assigned according to international response criteria guidelines prior to ASCT. Serum samples were analysed with Hevylite®, prior to ASCT (median: 2 days; range 0-77 days) and following ASCT (median: 50 days; range 22-119 days), on a SPAPLUS turbidimeter. HLC concentrations and ratios were compared to normal ranges (IgGk: 3.85-12.07 g/L; IgGl: 1.91-6.74 g/L; IgAk: 0.57-2.08 g/L; IgAλ: 0.44-2.04 g/L HLC ratio reference range: IgGk /IgGλ: 1.12-3.21; IgAk / IgAλ: 0.78-1.94). Progression free survival (PFS) was estimated by Kaplan Meier analysis and compared using a log rank test (Graphpad Prism).Results. Prior to ASCT, 1 patient achieved CR, 13 obtained VGPR, 9 obtained PR, 2 obtained (MR), 2 PD and 1 patient had no response assigned. An abnormal HLC ratio (18/28 patients) prior to ASCT was associated with significantly poorer PFS (17.1 months versus median not reached p=0.036). In comparison, achievement of ≥VGPR (14/28 patients) prior to ASCT was not associated with increased PFS (p=0.74). Addition of a normal HLC ratio to the assignment of response (in 8/14 patients achieving a ≥VGPR) added significant prognostic information and was significantly associated with improved PFS (median not reached versus 11.5 months, p=0.025). Suppression of the uninvolved HLC pair only (concentration below the normal reference range) prior to ASCT (15/28 patients) had no significant impact on PFS (p=0.32). Post-ASCT, an abnormal HLC ratio (11/28 patients) was not significantly associated with poorer PFS (p=0.18). However, suppression of the uninvolved HLC pair (6/28 patients) was significantly associated with poorer PFS (10.6 months versus median not reached p=0.013).Discussion. HLC analysis may provide early prognostic markers for PFS in MM patients receiving an ASCT. Warranting larger patient cohort studies, this preliminary data indicates that a normalised HLC ratio prior to ASCT and the absence of HLC paired suppression post-ASCT may be significant markers of improved PFS, adding prognostic information to current response criteria.Acknowledgments: This work was partially supported by the National Science Fund (D02-35/2009). DisclosuresGuenova:Novartis Pharma Sevices Bulgaria: Consultancy, Research Funding, Speakers Bureau; Roche Bulgaria: Consultancy, Research Funding, Speakers Bureau; Amgen Bulgaria: Consultancy, Research Funding, Speakers Bureau; Sanofi-Aventis Bulgaria: Consultancy, Research Funding, Speakers Bureau.

Comparison of IgA Heavy/Light Chain Immunoassays with Capillary Zone Electrophoresis and Total Immunoglobulin Measurements

Introduction: Capillary zone electrophoresis (CZE) and measurement of total immunoglobulins (total Ig) are standard techniques for the identification and quantification of monoclonal immunoglobulins (M-Ig). Heavy/light chain (HLC) pair analysis allows discrimination between Igκ and Igλ and as a result allows measurement of both the monoclonal involved and polyclonal uninvolved HLC pair. We compared measurement of M-Ig by CZE and total Ig to HLC levels.Methods: 93 samples from 8 patients with IgA intact immunoglobulin multiple myeloma (MM) were analysed. M-Ig was measured using CZE Sebia Capillarys 2 system, total IgA (tIgA) and IgAκ and IgAλ HLC concentrations on a SPAPLUS analyser. IgA HLC levels were measured with Hevylite® and compared to published normal ranges (IgAκ (g/L): 0.57-2.08, IgAλ (g/L): 0.44-2.04, IgAκ/IgAλ: 0.78-1.94). Passing and Bablok fit analysis was used to determine correlation between the assays.Results: Measurement of the involved HLC pair (iHLC) (median: 12.45g/L; range: 0.64-44.71g/L) compared well with CZE (n=34; median: 11.04g/L; range: 1.24-37.71g/L.; y= 1.2x + -2.65, R2= 0.94). Measurement of iHLC (median: 0.88. range: 0.05-21.55g/L) also compared well with tIgA measurement (n=65 median=1.44g/L; range: 0.227-21.11g/L, y=0.85x + -0.26, R2=0.98). Percent changes in iHLC concentrations from baseline through treatment compared well with CZE (n=28; y=1.59x + 0.15 R2=0.93) and tIgA (n=57; y=1.06x + 0.01, R2=0.96). Of the 34 samples with quantifiable M-protein by CZE, 32(94%) had an abnormal HLC ratio. The two discrepant samples were follow up samples from the same patient, where HLC normalised alongside total IgA entering the normal reference range. In addition, all 15 samples (15/65; 23%) where tIgA concentration was above the normal reference range all had abnormal HLC ratios. M-Ig was not detected by CZE in 48/82 (57%) samples, 46/48 of the samples (96%) had a normalised HLC ratio. In 38/65 (58%) samples, tIgA concentrations were within the normal reference range, and 34 (90%) had a normalised HLC ratio. HLC ratio for all patient samples normalised in subsequent samples following treatment.Conclusion: The measurement of M-Ig is comparable between Hevylite® and both CZE and tIgA. The presented data indicate that Hevylite® is a more sensitive test for detecting residual disease and warrants prospective studies on larger cohorts of patients.Acknowledgments:This work was partially supported by the National Science Fund (D02-35/2009). DisclosuresGuenova:Novartis Pharma Sevices Bulgaria: Consultancy, Research Funding, Speakers Bureau; Roche Bulgaria: Consultancy, Research Funding, Speakers Bureau; Amgen Bulgaria: Consultancy, Research Funding, Speakers Bureau; Sanofi-Aventis Bulgaria: Consultancy, Research Funding, Speakers Bureau.

Serum-free light-chain assay: clinical utility and limitations

In the last decade, the introduction of the serum-free light-chain (sFLC) assay has been an important advance in the diagnosis and management of plasma cell dyscrasias, particularly monoclonal light-chain diseases. The immunoassay was developed to detect free light chains in serum by using anti-FLC antibodies which specifically recognised epitopes on light chains that were 'hidden' in intact immunoglobulins. Since its introduction in 2001, there have been several publications in the English language literature discussing the clinical utility as well as analytical limitations of the sFLC assay. These studies have highlighted both positive and negative aspects of the assay particularly with regard to its sensitivity and specificity and the technical challenges that can affect its performance. The contribution and significance of the sFLC assay in the management of light-chain myeloma, primary amyloid light-chain (AL) amyloidosis and non-secretory myeloma are well recognised and will be addressed in this review. The aim of this article is to also review the published literature with a view to providing a clear understanding of its utility and limitations in the diagnosis, prognosis and monitoring of plasma dyscrasias including intact immunoglobulin multiple myeloma (MM) and monoclonal gammopathy of unknown significance (MGUS). The increasing interest in using this assay in other haematological conditions will also be briefly discussed.

Impact of Novel M-Component Based Biomarkers On to Progression Free Survival After Treatment in Intact Immunoglobulin Multiple Myeloma.

AbstractAbstract 2927 Background and Aims:Multiple Myeloma (MM) is characterized by bone marrow (BM) plasma cell infiltration and the presence of serum/urine monoclonal immunoglobulin (Ig). The depth of response has been associated with longer PFS in MM causing subsequent prolonged survival.Recently novel M-based biomarker immunoassays have been developed (Freelite™, Hevylite™) and their significance in MM diagnosis and prognosis has been demonstrated.1,2 Furthermore serum Free Light Chains (sFLC) are used for better assessment of treatment response, thus patients are considered to achieve stringed Complete Response (sCR) by having CR criteria plus normal serum Free Light Chains Ratio (sFLCR) and absent clonal cells on BM.3 The significance of Hevylite™ on response has not been assessed so far. Patients in nCR or better do not automatically restore their ratio of intact monoclonal Ig/intact polyclonal Ig of the same class (Hevylite™ or HLCR). We therefore investigated the importance of sFLCR and HLCR normalisation at plateau on PFS, in a series of patients with intact Ig MM. Patients and Methods:50 intact immunoglobulin MM patients were studied from diagnosis to last follow up. Immunofixation was IgG (26 -kappa and 12 –lamdba) and IgA (6 –kappa and 6 -lambda). All patients were symptomatic at diagnosis. Sera samples (n=312) were analyzed for sFLC-kappa and sFLC-lambda with Freelite™ and sFLCR were calculated, and for IgGkappa, IgGlambda IgAkappa, IgAlambda with Hevylite™ and ratios IgGkappa/IgGlambda, IgGlambda/IgGkappa, IgAkappa,/IgAlambda and IgAlambda/IgAkappa (HLCRs) were calculated. sFLCRs and HLCRs values above the 95%-ile of normal individuals were considered abnormal. Statistical analysis was performed using SPSS ver 15.0. File data were reviewed. Results:At diagnosis sFLCR was abnormal in 86% of patients while HLCR was abnormal in all. All treatment lines were initiated according to standard criteria and median lines of therapy were 2 (range 1–11). Median follow up was 33 months (7–145). During patients’ cumulative follow-up, 145 lines of therapy were studied and the subsequent responses were estimated. Thirty eight percent of responses were sCR, CR and nCR, 20% PR, 18% MR and 24% refractory and progressive disease. HLCR normalized in 44% of patients with sCR, CR and nCR. The depth of response correlated to PFS and patients in sCR, CR and nCR had longer PFS than the others (p<0.001). Serum FLCR and HLCR normal values at response were both strong parameters of increased PFS after treatment at any line (p=0.035 and p=0.046 respectively). Conclusion:Serum HLCR normalization at plateau reflects prolonged responses in intact Ig MM. Disclosures:Harding:Binding Site: Employment. Bradwell:The Binding Site: shareholder Other.

An Intact Immunoglobulin IgAλ Multiple Myeloma Patient Exhibiting Light Chain Escape

AbstractAbstract 5008A 48 year old man was referred to the Institute of Hematology and Transfusion Medicine, Warsaw, Poland in April 2008 with anemia (Hemoglobin; 10. 4 g/dl) and mild renal impairment (eGFR; 75. 4 mL/min/1. 73m2). An initial diagnostic monoclonal protein screen (serum protein electrophoresis (SPE), serum immunofixation electrophoresis (IFE) and serum free light chain (FLC) analysis) revealed an IgAλ monoclonal protein (0. 8g/dL) with monoclonal serum FLC and an abnormal serum FLC κ/λ ratio (0. 0001; RI, 0. 26–1. 65). A bone marrow biopsy at that time confirmed 60% involvement of monoclonal λ - restricted plasma cells; a bone survey did not detect any osteolysis. The patient was diagnosed with multiple myeloma (MM) (ISS stage I, Durie and Salmon stage IA) and was initially treated with 6 cycles of vincristin, doxorubicin and dexamethasone (VAD). The patient responded well to the induction treatment and subsequently underwent a successful autologous stem cell transplantation (ASCT).The patient was monitored for 3 years subsequent to the ASCT with both serum and urine electrophoresis, serum FLC analysis (Freelite) and heavy chain/light chain (HLC) immunoassays (Hevylite). Sixteen months following the ASCT the dFLC (involved λ FLC– uninvolved κ FLC) concentration began to increase, the FLC κ/λ ratio became abnormal with a trace of λ Bence Jones protein (BJP) detected by urine IFE. However, both SPE and IFE were normal and the HLC ratio (IgAλ/IgAκ) was within the normal range. During the next 9 months the dFLC continued to increase and a λ BJP could now be clearly detected on the urine IFE. 27 months following the ASCT the patient sustained a pathological fracture of the tibiae and was referred to our centre 4 months later. At this point, the dFLC concentration was highly elevated (3168 mg/L) with a λ BJP detectable by both serum and urine IFE. However, there was no detectable monoclonal intact immunoglobulin by serum IFE or HLC analysis, indicating disease relapse by a separate FLC clone; referred to as light chain escape (LCE). A bone marrow biopsy revealed 15% involvement of λ restricted plasma cells; this time a bone survey identified osteolysis. The patient was diagnosed with progression of multiple myeloma and received 6 cycles of bortezomib, cyclophosphamide and dexamethasone (VCD regimen). He responded well to treatment and 3 years following the ASCT achieved a CR as indicated by a normalized κ/λ FLC ratio, negative immunofixation with 1–3% bone marrow plasma cells. The patient is now well and able to continue with normal life.In this case study the increase in the dFLC levels was the first indication of disease progression and highlights the importance of monitoring intact immunoglobulin MM patients with serum FLC immunoassays for early detection of LCE. Disclosures:Endean:The Binding Site Group Ltd: Employment. Harding:Binding Site: Employment.