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

Progression free survival of myeloma patients who become IFE-negative correlates with the detection of residual monoclonal free light chain (FLC) by mass spectrometry

Deeper responses are associated with improved survival in patients being treated for myeloma. However, the sensitivity of the current blood-based assays is limited. Historical studies suggested that normalisation of the serum free light chain (FLC) ratio in patients who were negative by immunofixation electrophoresis (IFE) was associated with improved outcomes. However, recently this has been called into question. Mass spectrometry (MS)-based FLC assessments may offer a superior methodology for the detection of monoclonal FLC due to greater sensitivity. To test this hypothesis, all available samples from patients who were IFE negative after treatment with carfilzomib and lenalidomide-based induction and autologous stem cell transplantation (ASCT) in the Myeloma XI trial underwent FLC-MS testing. FLC-MS response assessments from post-induction, day+100 post-ASCT and six months post-maintenance randomisation were compared to serum FLC assay results. Almost 40% of patients had discordant results and 28.7% of patients with a normal FLC ratio had residual monoclonal FLC detectable by FLC-MS. FLC-MS positivity was associated with reduced progression-free survival (PFS) but an abnormal FLC ratio was not. This study demonstrates that FLC-MS provides a superior methodology for the detection of residual monoclonal FLC with FLC-MS positivity identifying IFE-negative patients who are at higher risk of early progression.

Performance Characteristics and Limitations of the Available Assays for the Detection and Quantitation of Monoclonal Free Light Chains and New Emerging Methodologies

Light chain measurements form an essential component of the testing strategy for the detection and monitoring of patients with suspected and/or proven plasma cell disorders. Urine-based electrophoretic assays remain at the centre of the international guidelines for response assessment but the supplementary role of serum-free light chain (FLC) assays in response assessment and the detection of disease progression due to their increased sensitivity has been increasingly recognised since their introduction in 2001. Serum FLC assays have also been shown to be prognostic across the spectrum of plasma cell disorders and are now incorporated into risk stratification scores for patients with monoclonal gammopathy of undetermined significance (MGUS), smouldering multiple myeloma, and light chain amyloidosis (AL amyloidosis), as well as being incorporated into the criteria for defining symptomatic multiple myeloma. There are now multiple different commercially available serum FLC assays available with differing performance characteristics, which are discussed in this review, along with the implications of these for patient monitoring. Finally, newer methodologies for the identification and characterisation of monoclonal FLC, including modifications to electrophoretic techniques, mass spectrometry-based assays and Amylite, are also described along with the relevant published data available regarding the performance of each assay.

Non-Secretory Multiple Myeloma: A New Observation and Review of the Literature

Non-secreting multiple myeloma is a rare variant of multiple myeloma that affects a relatively young population. It is characterized by the non-secretory nature of malignant plasma cells. The following case report describes the history of a 54-year-old patient with non-secretory myeloma revealed by mechanical and inflammatory low back pain. The bone and neurological involvement, the presence of diffuse osteolytic lesions and the increase in the serum kappa free light chains (FLC) level prompted a myelogram. This finds medullary invasion by dystrophic plasma cells. The absence of detection of complete or incomplete monoclonal immunoglobulin in the blood and urine, as well as the revelation of cytogenetic abnormalities of plasma cells, allows the diagnosis of non-secreting multiple myeloma to be made. This clinical case aims to describe the unusual presentation of this rare form of multiple myeloma.

Laboratory practice is central to earlier myeloma diagnosis: Utilizing a primary care diagnostic tool and laboratory guidelines integrated into haematology services

Treatment advances have greatly improved survival, but myeloma is among the worst of all cancers for delayed diagnosis, causing serious morbidities and early deaths. This delay is largely because the symptom profile of myeloma has very low specificity, and in primary care, myeloma is rare. However, initiating the journey to diagnosis simply requires considering myeloma and sending blood to test for monoclonal immunoglobulin. Laboratory tests reliably detect monoclonal immunoglobulin, which is present in 99% of myeloma cases, so why do health care systems have such a problem with delayed diagnosis? The Myeloma UK early diagnosis programme has brought together diverse expertise to investigate this problem, and this article was prepared by the programme's working group for laboratory best practice. It reviews evidence for test requesting, analysis and reporting, for which there is large variation in practice across the United Kingdom. It presents a 'GP Myeloma diagnostic tool' and how it can be integrated into laboratory practice alongside a laboratory best practice tool. It proposes improved requesting and integration with haematology services for reporting and interpretation. Here the laboratory has a central role in creating efficient and cost-effective pathways for appropriate and timely bone marrow examination for myeloma diagnosis.

Current barriers and recommendations on the diagnosis of transthyretin amyloid cardiomyopathy: a Delphi study

Objectives

This study has been conducted to investigate the non-invasive diagnostic journey of patients with a transthyretin amyloid cardiomyopathy (aTTR-CM) in Turkey, identify the challenges and uncertainties encountered on the path to diagnosis from the perspectives of expert physicians, and develop recommendations that can be applied in such cases.

Methods

This study employed a three-round modified Delphi method and included 10 cardiologists and five nuclear medicine specialists. Two hematologists also shared their expert opinions on the survey results related to hematological tests during a final face-to-face discussion. A consensus was reached when 80% or more of the panel members marked the "agree/strongly agree" or "disagree/strongly disagree" option.

Results

The panelists unanimously agreed that the aTTR-CM diagnosis could be established through scintigraphy (using either 99mTc-PYP, 99mTc-DPD, or 99mTc-HMPD) in a patient with suspected cardiac amyloidosis (CA) without a further investigation if AL amyloidosis is ruled out (by sFLC, SPIE and UPIE). In addition, scintigraphy imaging performed by SPECT or SPECT-CT should reveal a myocardial uptake of Grade ≥2 with a heart-to-contralateral (H/CL) ratio of ≥1.5. The cardiology panelists recommended using cardiovascular magnetic resonance (CMR) and a detailed echocardiographic scoring as a last resort before considering an endomyocardial biopsy in patients with suspected CA whose scintigraphy results were discordant/inconclusive or negative but still carried a high clinical suspicion of aTTR-CM.

Conclusion

The diagnostic approach for aTTR-CM should be customized based on the availability of diagnostic tools/methods in each expert clinic to achieve a timely and definitive diagnosis.

The novel norcantharidin derivative DCZ5417 suppresses multiple myeloma progression by targeting the TRIP13-MAPK-YWHAE signaling pathway

BACKGROUND

Multiple myeloma (MM), an incurable disease owing to drug resistance, requires safe and effective therapies. Norcantharidin (NCTD), an active ingredient in traditional Chinese medicines, possesses activity against different cancers. However, its toxicity and narrow treatment window limit its clinical application. In this study, we synthesized a series of derivatives of NCTD to address this. Among these compounds, DCZ5417 demonstrated the greatest anti-MM effect and fewest side effects. Its anti-myeloma effects and  the mechanism were further tested.

METHODS

Molecular docking, pull-down, surface plasmon resonance-binding, cellular thermal shift, and ATPase assays were used to study the targets of DCZ5417. Bioinformatic, genetic, and pharmacological approaches were used to elucidate the mechanisms associated with DCZ5417 activity.

RESULTS

We confirmed a highly potent interaction between DCZ5417 and TRIP13. DCZ5417 inhibited the ATPase activity of TRIP13, and its anti-MM activity was found to depend on TRIP13. A mechanistic study verified that DCZ5417 suppressed cell proliferation by targeting TRIP13, disturbing the TRIP13/YWHAE complex and inhibiting the ERK/MAPK signaling axis. DCZ5417 also showed a combined lethal effect with traditional anti-MM drugs. Furthermore, the tumor growth-inhibitory effect of DCZ5417 was demonstrated using in vivo tumor xenograft models.

CONCLUSIONS

DCZ5417 suppresses MM progression in vitro, in vivo, and in primary cells from drug-resistant patients, affecting cell proliferation by targeting TRIP13, destroying the TRIP13/YWHAE complex, and inhibiting ERK/MAPK signaling. These results imply a new and effective therapeutic strategy for MM treatment.

Screening for and diagnosis of monoclonal gammopathy

Monoclonal gammopathy is a spectrum of disorders characterised by clonal proliferation of plasma cells or lymphocytes, which produce abnormal immunoglobulin or its components (monoclonal proteins). Monoclonal gammopathies are often categorised as low-tumour-burden diseases (eg, amyloid light chain (AL) amyloidosis), premalignant disorders (such as monoclonal gammopathy of undetermined significance and smouldering multiple myeloma), and malignancies (eg, multiple myeloma and Waldenström's macroglobulinaemia). Such diversity of concentration and structure makes monoclonal protein a challenging clonal marker. This article provides an overview on initial laboratory testing of monoclonal gammopathy to guide clinicians and laboratory professionals in the selection and interpretation of appropriate investigations.

Outcome and characteristics of nonsecretory multiple myeloma compared with secretory multiple myeloma: a retrospective multicenter study from China

BACKGROUND

Nonsecretory multiple myeloma (NSMM) is a rare type of multiple myeloma (MM). Few studies have described the clinical features and outcomes of NSMM in novel agents. Additionally, the prognostic characteristics have remained controversial in recent years.

PURPOSE

To investigate the clinical and prognostic features of NSMM and explore the prognostic value of involved free light chain (FLC) levels in NSMM patients in the Chinese population.

METHODS

We retrospectively enrolled 176 newly diagnosed NSMM cases between January 2005 and December 2021 from 19 clinical centers in China. The control group was selected using a 1:4 propensity score matching technique of newly diagnosed secretory MM, with age, sex and diagnosis time as the matching variables.

RESULTS

The median age of NSMM patients was 60 years, and 22.6% of patients were classified as ISS stage 3. The ORR of the NSMM patients was 87.4%, and the CR was 65.8%. Compared to the matched secretory MM patients, more NSMM patients achieved CR after first-line treatment (65.8% vs. 36%, p = 0.000). The ORR of first-line treatment was not significantly different between NSMM and secretory MM (89.45% vs. 84.7%, p = 0.196). The first-line PFS was 27.5 m and 23 m (p = 0.063), and the median OS was 81 m and 70 months (p = 0.401). However, for CR-achieved NSMM and CR-not-achieved NSMM patients, the median PFS was 37 m vs. 16 m (p = 0.021), while the median OS showed no difference (107 m vs. 87 m, p = 0.290). In multivariate analysis, the significant factors for PFS were age ≥ 65 and ISS-3. ISS-3 was the only independent prognostic factor of OS. The iFLC ≥ 50 mg/L group had a high ORR of 97.3%, and the median PFS and OS were 48 m and NR, respectively. Compared to the matched secretory MM, the iFLC ≥ 50 mg/L group also showed more CR and longer OS (NR vs. 70 m, p = 0.006) and PFS (48 m vs. 23 m, p = 0.003).

CONCLUSIONS

Our results revealed that Chinese NSMM patients are younger and have a higher CR but not superior survival. The subgroup of NSMM patients with iFLC ≥ 50 mg/L had better outcomes than secretory MM.

The relationship between immunohistochemical parameters, bone marrow fibrosis and bone marrow 18F-FDG uptake in multiple myeloma patients undergoing PET/CT examination

PURPOSE

The aim of this study was to determine the power of the SUVmax value obtained from 18F-FDG PET/CT in multiple myeloma (MM) patients to be able to predict immunophenotype characteristics (CD20, CD44, CD56, CD117, CD138 antigen expressions), bone marrow fibrosis, cyclin D1 oncogene, and M-protein subtypes which play a role in diagnosis-treatment and prognosis of the disease.

MATERIAL AND METHOD

The study included 54 patients with multiple myeloma who underwent PET/CT for initial staging and bone marrow biopsy. The relationship was examined in these patients between the SUVmax value measured from the iliac bone region and the immunohistochemical and bone marrow fibrosis data of the biopsy taken from the iliac bone. The Mann Whitney U test was used in the comparisons of dependent paired groups, and the Kruskal Wallis H test in the comparisons of three or more groups.

RESULTS

The median SUVmax value was 4.5 (1.9-15.6) in patients with CD117 antigen positivity, which was statistically significantly higher than the value in the patients with CD117 negativity (p = 0.031). When patient grouping was made according to the reticulin level; we found that the median SUVmax value was 4.9 (3.0-14.8) in the group with increased fibrosis and 3.6 (1.6-15.6) in the group with low fibrosis. The median SUVmax was statistically significantly higher in the group with increased fibrosis compared to the group with low fibrosis (p = 0.004). No statistically significant difference was determined in the comparisons of the SUVmax values when the patients were grouped according to the immunoglobulin heavy chain and light chain, CD20, CD44, CD56, and cyclin D1 characteristics (p > 0.05).

CONCLUSION

In MM patients who underwent PET/CT for initial staging, significant relationships were determined between FDG uptake in the bone marrow (SUVmax) and CD117 antigen and bone marrow fibrosis, which is an important prognostic factor. Higher SUVmax values were determined in the bone marrow of patients with increased fibrosis and CD117 positivity.

First Line Treatment of Newly Diagnosed Transplant Ineligible Multiple Myeloma: Recommendations from the Canadian Myeloma Research Group Consensus Guideline Consortium

Although the availability of effective novel treatments has positively impacted the quality of life and survival of newly diagnosed multiple myeloma (MM) patients, benefits in the transplant ineligible MM population may be limited by functional/frailty status. The Canadian Myeloma Research Group Consensus Guideline Consortium proposes consensus recommendations for the first-line treatment of transplant ineligible MM. To address the needs of physicians and people diagnosed with MM, this document further focuses on eligibility for transplant, frailty assessment, management of adverse events, assessment of treatment response, and monitoring for disease relapse. The Canadian Myeloma Research Group Consensus Guideline Consortium will periodically review the recommendations herein and update as necessary.

Use of Clinical Decision Support to Improve the Laboratory Evaluation of Monoclonal Gammopathies

OBJECTIVES

There is considerable variation in ordering practices for the initial laboratory evaluation of monoclonal gammopathies (MGs) despite clear society guidelines to include serum free light chain (sFLC) testing. We assessed the ability of a clinical decision support (CDS) alert to improve guideline compliance and analyzed its clinical impact.

METHODS

We designed and deployed a targeted CDS alert to educate and prompt providers to order an sFLC assay when ordering serum protein electrophoresis (SPEP) testing.

RESULTS

The alert was highly effective at increasing the co-ordering of SPEP and sFLC testing. Preimplementation, 62.8% of all SPEP evaluations included sFLC testing, while nearly 90% of evaluations included an sFLC assay postimplementation. In patients with no prior sFLC testing, analysis of sFLC orders prompted by the alert led to the determination that 28.9% (800/2,769) of these patients had an abnormal κ/λ ratio. In 452 of these patients, the sFLC assay provided the only laboratory evidence of a monoclonal protein. Moreover, within this population, there were numerous instances of new diagnoses of multiple myeloma and other MGs.

CONCLUSIONS

The CDS alert increased compliance with society guidelines and improved the diagnostic evaluation of patients with suspected MGs.

Role of serum-free light chain assay for defining response and progression in immunoglobulin secretory multiple myeloma

The International Myeloma Working Group (IMWG) guidelines recommend using electrophoresis and immunofixation to define response and progressive disease (PD) in immunoglobulin (Ig) secretory multiple myeloma (Ig-MM), whereas the role of serum-free light chain (sFLC) is controversial. We retrospectively analyzed the value of adding sFLC assays in the definition of response and PD according to IMWG criteria in 339 Ig-MM patients treated with a first-line novel agent-based therapy (median follow-up 54 months). sFLC PD was defined according to conventional criteria plus increased sFLC levels, or sFLC escape (sFLCe); progression/sFLCe-free survival (ePFS) was the time from the start of treatment to the date of first PD or sFLCe, or death; overall survival after PD/sFLCe (OS after Pe) was the time from first PD or sFLCe to the date of death. 148 (44%) patients achieved a complete response and 198 (60%) a normal sFLC ratio (sFLCR). sFLCR normalization was an independent prognostic factor for extended PFS (HR = 0.46, p = 0.001) and OS (HR = 0.47, p = 0.006) by multivariable analysis. 175 (52%) patients experienced PD according to the IMWG criteria, whereas 180 (53%) experienced PD or sFLCe. Overall, a sFLCe was observed in 31 (9%) patients. Median PFS and ePFS were both equal to 36 (95% CI = 32-42, and 32-40, respectively) months. sFLC PD adversely affected the OS after Pe compared to PD with increasing monoclonal Ig only (HR = 0.52, p = 0.012). Our results support the inclusion of the sFLC assay for defining response and PD in Ig-MM.

An Analysis of M-protein in Plasma cell Dyscrasia Patients Identifies that IgG Lambda Subtype is More Commonly Associated with Normal Serum Free Light Chain (SFLC) Ratio

The determination of monoclonal protein (M-protein) by SPE, IFE and SFLC assay is fundamental in the diagnosis of Plasma cell proliferative disorder (PCPD). In the present study, we seek to assess the diagnostic performance and concordance of these three techniques in un-treated PCPD patients. All new patients with dysproteinemia and/or suspected PCPD were included in this retrospective observational study. The baseline parameters were retrieved from electronic medical records. SPE was performed on gel electrophoresis system; monoclonal component was identified by IFE. SFLC assays were performed by nephelometry using a latex-enhanced immunoassay. Total 402 patients of PCPD were included (10.9% of MGUS/SMM and 89.1% of multiple myeloma). The combination of SPE + rSFLC (ratio of kappa/lambda light chain) and SPE + IFE + rSFLC was able to detect M-protein across all subgroups of patients. In 61 patients, rSFLC values were within normal range (54.5% of MGUS/SMM and 10.3% of MM) and was more commonly seen with IgG lambda M-protein (57.4% vs. all-others). The median dFLC value, among these patients, was higher for MM than MGUS/SMM patients (23.8 vs. 14.4 mg/L, respectively). The combination of SPE and rSFLC can be reliably used to detect M-protein in PCPD patients. In a small subgroup of MM patients, despite the presence of an intact immunoglobulin (M-protein), the rSFLC is not abnormal. Historically, these patients should respond better to treatment. However, a further follow-up analysis with more number of such patients would be advantageous for better understanding.

Clinical characteristics and outcomes of IgD myeloma: experience across UK national trials

Immunoglobulin D (IgD) myeloma is a subtype often considered to have adverse features and inferior survival, but there is a paucity of data from large clinical studies. We compare the clinical characteristics and outcomes of patients with IgD myeloma from UK phase 3 myeloma trials analyzed in 2 groups: old (1980-2002) and recent (2002-2016) clinical trials, based on the time of adoption of novel myeloma therapies. Patients with IgD myeloma comprised 44 of 2789 (1.6%) and 70 of 5773 (1.2%) of the old and recent trials, respectively. Overall, IgD myeloma was associated with male predominance, low-level paraproteinemia (<10g/L), and λ light chain preference. The frequency of ultra-high-risk cytogenetics was similar in IgD myeloma compared with other subtypes (4.3% vs 5.3%, P > .99). Despite the old trial series being a younger group (median age: 59 vs 63 years, P = .015), there was a higher frequency of bone lesions, advanced stage at diagnosis, worse performance status, and severe renal impairment compared with the recent trials. Furthermore, the early mortality rate was significantly higher for the old trial series (20% vs 4%, P = .01). The overall response rate following induction therapy was significantly higher in the recent trials (89% vs 43%, P < .0001), and this was consistent with improved median overall survival (48 months; 95% confidence interval [CI] 35-67 months vs 22 months; 95% CI, 16-29 months). Survival outcomes for IgD myeloma have significantly improved and are now comparable to other myeloma types because of earlier diagnosis, novel therapies, and improved supportive care. This trial was registered at clinicaltrials.gov as # NCT01554852.

A Case of Plasma Cell Myeloma with Multilobated and Monocytoid Morphology

Plasma cell myeloma (PCM) accounts for approximately 1% of malignant tumors and 10 to 15% of hematological neoplasms. It is a malignant disease characterized by abnormal proliferation of plasma cells and monoclonal immunoglobulins or free light chains (FLCs). There are many morphological variations of the myeloma plasma cells which include mature, immature, plasmablastic, and pleomorphic types. Here, we report a rare presentation of PCM with normal serum protein electrophoresis but elevated serum FLCs and having convoluted, multilobated, and monocytoid morphology. This type of morphology is related to an aggressive clinical course and resistance to conventional chemotherapy. Moreover, absence of M protein in serum/urine electrophoresis does not rule out the diagnosis of PCM and serum FLC assays plays an important role in this kind of scenarios.

A Cohort Study of Free Light Chain Ratio in Combination with Serum Protein Electrophoresis as a First-Line Test in General Practice

Simple Summary

Multiple Myeloma (MM) can be a diagnostic challenge as it often presents with unspecific symptoms in patients in general practice. Serum-free light chain (sFLC) ratio is suggested to replace urine protein electrophoresis (UPE) in the diagnostic work-up of myeloma. We aimed to investigate the performance of the sFLC ratio in general practice (GP) compared to UPE in a low prevalence cohort of 13,210 patients from general practice. We found that sFLC ratio performs in line with UPE; however, we observed a pronounced number of false-positive tests. Therefore, local instrument-dependent adjustment of reference ranges/decision limits should be considered to avoid an unnecessarily high number of false-positive tests.

Abstract

Multiple Myeloma (MM) often present with unspecific symptoms, which can lead to diagnostic delay. Serum-free light chain (sFLC) ratio is suggested to replace urine protein electrophoresis (UPE) in the diagnostic work-up of myeloma. We aimed to investigate the performance of the sFLC-ratio in general practice (GP) compared to UPE, just as we explored different sFLC-ratio cut-offs’ influence on diagnostic values. In a cohort of 13,210 patients from GP measures of sFLC-ratio, serum protein electrophoresis (SPE), or UPE were compared to diagnoses of incident M-component related diseases acquired from Danish health registers. UPE and sFLC-ratio equally improved diagnostic values when combined with SPE (sensitivity: SPE and UPE: 95.6 (90.6–98.4); SPE and sFLC-ratio: 95.1 (90.2–98.0)). The addition of the sFLC-ratio to SPE resulted in the identification of 13 patients with MGUS, light chain disease and amyloidosis, which was in line with the addition of UPE to SPE. The number of false-positive tests was UPE and SPE: 364 (11%) and sFLC-ratio and SPE: 677(19%). Expanding sFLC-ratio reference range to 0.26–4.32 resulted in a significant reduction in false positives n = 226 (6%) without loss of patients with clinical plasma cell dyscrasias. sFLC-ratio improves the diagnostic value of SPE in GP. However, due to low specificity and a large number of false positives, expanded cut-off values should be considered.

Mono/polyclonal free light chains as challenging biomarkers for immunological abnormalities

Free light chain (FLC) kappa (k) and lambda (λ) consist of low molecular weight proteins produced in excess during immunoglobulin synthesis and secreted into the circulation. In patients with normal renal function, over 99% of FLCs are filtered and reabsorbed. Thus, the presence of FLCs in the serum is directly related to plasma cell activity and the balance between production and renal clearance. FLCs are bioactive molecules that may exist as monoclonal (m) and polyclonal (p) FLCs. These have been detected in several body fluids and may be key indicators of ongoing damage and/or illness. International guidelines now recommend mFLC for screening, diagnosis and monitoring multiple myeloma and other plasma cell dyscrasias. In current clinical practice, FLCs in urine indicate cast nephropathy and other renal injury, whereas their presence in cerebrospinal fluid is important for identifying central nervous system inflammatory diseases such as multiple sclerosis. Increased pFLCs have also been detected in various conditions characterized by B cell activation, i.e., chronic inflammation, autoimmune disease and HCV infection. Monitoring the coronavirus (COVID-19) pandemic by analysis of salivary FLCs presents a significant opportunity in clinical immunology worthy of scientific pursuit.

Effectiveness and safety of chemotherapy combined with immunomodulatory therapies for multiple myeloma: A protocol for systematic review and meta-analysis

BACKGROUND

Multiple myeloma (MM) is considered one of the prevalent malignant plasma cell diseases affecting people. In essence, maintenance treatment is valuable for prolonging the survival time of patients experiencing MM. The majority of the currently used treatment protocols for MM are founded on a combination of chemotherapy and immunomodulatory drugs, of which immunomodulatory drugs seems to be one of the most active drugs. However, in the literature, chemotherapy combined with immunomodulatory therapies have not been unambiguously proven. To systematically appraise and synthesize these results, the present investigation will evaluate whether combining chemotherapy with immunomodulatory therapies an effective and safe approach to treating patients with MM.

METHODS

Two authors relied in 7 different databases: PubMed, EMBASE, Cochrane Library, Web of Science, WanFang Database, Chinese Biomedical Literature Database, China National Knowledge Infrastructure and for studies on chemotherapy's effectiveness when combined with immunomodulatory therapies. The authors only considered studies published up to December 16, 2021 and only those written in English or Chinese. They will also carry out selection of studies, extraction of data, along with assessing risk of bias. Besides, they will also use RevMan V.5.3 to conduct data synthesis. They will establish heterogeneity using the I2 test. At the same time, the authors will evaluate publication bias by making a funnel plot and conducting the Begg as well as Egger tests.

ETHICS AND DISSEMINATION

The present study will not necessitate ethics approval since it will be funded on already published works.

OSF REGISTRATION NUMBER

10.17605/OSF.IO/X7DE4.

Comparison of clinical and laboratory characteristics of nonsecretory multiple myeloma and secretory multiple myeloma in a tertiary care hospital

INTRODUCTION

Nonsecretory multiple myeloma (NSM) is a rare variant of multiple myeloma, accounting for approximately 1%-5% of all reported cases. We compared the characteristics of NSM and secretory multiple myeloma (SM).

METHODS

We examined clinical and laboratory characteristics of 17 patients diagnosed with NSM and 40 patients diagnosed with SM. NSM was diagnosed based on findings of bone marrow (BM) examination, serum-free light chain (sFLC) assay, flow cytometric (FCM) immunophenotyping, chromosomal analysis, and imaging studies.

RESULTS

No patient with NSM had hypercalcemia or renal insufficiency at diagnosis. Patients with NSM were less anemic (p < .05) but had higher lactate dehydrogenase levels (p < .05) than patients with SM. In addition, patients with NSM had a lower percentage of plasma cells in the BM, confirmed by manual differential count (p < .05) and FCM immunophenotyping (p < .05). The sFLC ratio in patients with NSM was abnormal (15/17, 88.2%) and was lower than that in patients with SM (p < .05). Risk stratification in Revised International Staging System revealed a low-risk tendency in patients with NSM (p = .235).

CONCLUSION

NSM patients showed different clinical and laboratory characteristics from SM patients. FCM immunophenotyping and sFLC assay particularly had differences between NSM patients and SM patients. Thus, they are essential for diagnosing NSM.

Active Components of Traditional Chinese Medicinal Material for Multiple Myeloma: Current Evidence and Future Directions

Multiple myeloma (MM) is a hematological malignancy characterized by clonal expansion of plasma cells in bone marrow, leading to the overproduction of monoclonal immunoglobulins. The clinical manifestations resulting from monoclonal proteins and malignant cells include signs of end-organ damage, such as hypercalcemia, renal failure, anemia, and bone lesions. Despite improvement in the survival of MM patients with use of myeloma-targeted and immunomodulatory therapies, MM remains an incurable disease. Moreover, patients with relapsed or refractory MM show poor survival outcomes. In recent years, there has been a growing interest in the use of traditional Chinese medicinal materials (TCMMs) for management of a wide spectrum of diseases. The bioactive ingredients derived from TCMMs hold great potential for the development of anticancer drugs. Here we summarize the evidence of the pharmacological effects of the active components in TCMMs on MM, including curcumin, resveratrol, baicalein, berberine, bufalin, cinobufagin, gambogic acid, ginsenoside, icariin, daidzin, formononetin, polysaccharides extracts from Hedyotis difus, and scutellarein. Available evidence indicates that the anti-MM effects of these bioactive ingredients are mediated via regulation of proliferation, apoptosis, autophagy, cell cycle, osteogenic differentiation, and drug resistance. In the future, the underlying mechanisms of the anti-MM effects of these components should be further investigated. Large-scale and well-designed clinical trials are also required to validate the efficacy of these bioactive constituents for MM.

Multiple myeloma: therapeutic delivery of antibodies and aptamers

Multiple myeloma is the second most common hematological malignancy in adults, accounting for 2% of all cancer-related deaths in the UK. Current chemotherapy-based regimes are insufficient, as most patients relapse and develop therapy resistance. This review focuses on current novel antibody- and aptamer-based therapies aiming to overcome current therapy limitations, as well as their respective limitations and areas of improvement. The use of computer modeling methods, as a tool to study and improve ligand-receptor alignments for the use of novel therapy development will also be discussed, as it has become a rapid, reliable and comparatively inexpensive method of investigation.

Limitations of Free Light Chain Assays caused by the Matrix Effect

BACKGROUND

Serum free light chain (FLC) assays are used clinically to measure the concentration of κ and λ FLC in patients with suspected or diagnosed plasma cell proliferative disorders. Previous studies have demonstrated a loss of linearity in low concentration ranges of these assays. We hypothesized that this result could be caused by a matrix effect.

METHODS

Recovery studies were performed for κ and λ FLC in both serum and saline using the Freelite assay (Binding Site) on a Cobas c502 system (Roche). Samples were analyzed either at the recommended dilution or undiluted. Follow-up studies were performed in varying matrices ranging from 0% to 100% saline. Retrospective patient data were analyzed to assess the impact on reported κ FLC, λ FLC, and κ/λ ratio.

RESULTS

FLC in a serum matrix demonstrated underrecovery relative to samples diluted in saline for both κ and λ FLC. Of 255 patient samples with λ FLC measured undiluted (λ FLC <6.0 mg/L), an unexpected gap was observed in patient results between 2.0 and 6.0 mg/L. In addition, 23 patients measured serially with λ FLC between 2.0 and 6.0 mg/L demonstrated dramatic changes in κ/λ ratio, with no changes in κ FLC, likely because of the matrix effect.

CONCLUSIONS

The κ and λ Freelite assays exhibit a matrix effect when samples are tested undiluted, which has the potential to affect the κ/λ ratio. Consequently, our laboratory has stopped reporting λ FLC <6.0 mg/L.

Hypoglobulinemia in a dog with disseminated plasma cell neoplasia: Case report and review of the diagnostic criteria

This is the first reported case of hypoglobulinemia in a dog with disseminated plasma cell neoplasia. A 6-year-old male intact Rottweiler was referred to the U-Vet Animal Hospital (Werribee, Vic, Australia) for weight loss, hyporexia, lethargy, vomiting, and soft stools. Examination of a buffy coat preparation and splenic and liver aspirates revealed a monomorphic population of plasmacytoid cells, and the same cells comprised approximately 90% of bone marrow samples submitted for cytologic and histologic evaluation. Biochemistry revealed a hypoglobulinemia, and the presence of an M-protein was not supported by serum and urine protein electrophoresis or serum immunofixation. Immunohistochemistry demonstrated strong nuclear labeling for MUM-1.

Serum free light chain assessment in type 1 autoimmune pancreatitis

BACKGROUND

/Object: Some patients with type 1 autoimmune pancreatitis (AIP), the pancreatic manifestation of IgG4-related disease, have normal serum IgG4. The aim of this study is to investigate the diagnostic value of measuring serum free light chains (FLCs) in type 1 AIP.

MATERIALS AND METHODS

Thirty-seven patients with type 1 AIP, and 21 healthy, 17 alcoholic chronic pancreatitis (ACP), 21 idiopathic chronic pancreatitis (ICP) and 20 pancreatic cancer (PC) patients were enrolled. Serum IgG4 and FLC concentrations were measured using sFLC Freelite assays on a nephelometric analyzer.

RESULTS

Active AIP patients have significantly higher serum levels of κ (median 30.97 (12.3-227.0) mg/L) and λFLC (median 20.53 (12.36-102.7) mg/L)) than healthy controls (κFLC; median 12.5 (3.1-52.1) mg/L), λFLC: median 12.45 (5.4-39.5) mg/L) (p < 0.05) correlating with raised serum IgG4, and significantly higher summated FLCs (∑) (median 53.09 (25.0-218.0) mg/L) than ICP patients (median 26.77 (15.0-89.2) mg/L) and healthy controls (median 24.43 (8.5-91.6) mg/L) (p < 0.05). AIP patients (median 1.43 (0.84-3.24)) showed significantly higher κ/λ ratios than ACP (median 0.83 (0.42-1.18)), ICP (median 0.87 (0.47-2.16)), PC patients (median 0.90 (0.48-1.27)) and healthy controls (median 0.963 (0.51-1.32)). There was a correlation between increased κ and λ FLCs levels and the number of affected organs involved in IgG4 related disease.

CONCLUSION

Patients with type 1 AIP have increased serum k and λ FLC concentrations, Σ FLC, and κ/λ ratios. These novel biomarkers may be useful in the diagnosis of type 1 AIP and in monitoring disease activity.

Light chain myeloma and detection of free light chains in serum and urine of dogs and cats

Background

Detection of free light chains (fLC) in animals relies on protein electrophoresis or the Bence‐Jones protein test on urine.

Objective

To describe the detection of both serum fLC (sfLC) and urine fLC (ufLC) in 8 dogs and 2 cats using a commercially available human immunofixation (IF) kit.

Animals

Archived serum or urine samples from 27 dogs and 2 cats submitted to the Colorado State University Veterinary Diagnostic Laboratory for routine diagnostics.

Methods

Retrospective study evaluating the presence of fLC in dogs and cats using agarose gel electrophoresis and routine and fLC IF performed on serum and urine. The performance of the fLC IF reagents was evaluated using samples characterized by routine IF, tandem mass spectrometry, and a combination of fLC IF and western blotting. Free light chains were documented by paired electrophoresis and fLC IF.

Results

The fLC only myeloma case developed end‐stage renal failure 5 months post initial diagnosis. All electrophoresis‐defined urinary Bence‐Jones proteins were labeled by the anti‐free λ light chain (anti‐fλ) reagent; none were labeled by the anti‐free κ light chain (anti‐fκ); 2 of these were identified as fκ by mass spectrometry. An electrophoretically identical protein restriction that was labeled by the anti‐fλ reagent was present in the paired serum from 5/8 of cases, documenting sfLC.

Conclusions and Clinical Importance

Commercially available human IF reagents identified sfLC and ufLC in both dogs and cats. Free light chains may be nephrotoxic in dogs.

Anti-Cancer Activity of Curcumin on Multiple Myeloma

Multiple Myeloma (MM) is the third most common and deadly hematological malignancy, which is characterized by a progressive monoclonal proliferation within the bone marrow. MM is cytogenetically heterogeneous with numerous genetic and epigenetic alterations, which lead to a wide spectrum of signaling pathways and cell cycle checkpoint aberrations. MM symptoms can be attributed to CRAB features (hyperCalcemia, Renal failure, Anemia, and Bone lesion), which profoundly affect both the Health-Related Quality of Life (HRQoL) and the life expectancy of patients. Despite all enhancement and improvement in therapeutic strategies, MM is almost incurable, and patients suffering from this disease eventually relapse. Curcumin is an active and non-toxic phenolic compound, isolated from the rhizome of Curcuma longa L. It has been widely studied and has a confirmed broad range of therapeutic properties, especially anti-cancer activity, and others, including anti-proliferation, anti-angiogenesis, antioxidant and anti-mutation activities. Curcumin induces apoptosis in cancerous cells and prevents Multidrug Resistance (MDR). Growing evidence concerning the therapeutic properties of curcumin caused a pharmacological impact on MM. It is confirmed that curcumin interferes with various signaling pathways and cell cycle checkpoints, and with oncogenes. In this paper, we summarized the anti- MM effects of curcumin.

A challenging diagnosis of a nonsecretor plasma cell dyscrasia with pleomorphic plasmablastic morphology

This report highlights the importance of integrating clinical, radiological, genetic, and pathological laboratory findings to make a correct diagnosis especially with challenging and rare entities.

Multiple Myeloma: Role of Imaging in Diagnosis, Staging, and Treatment Response Assessment

Multiple myeloma is a common hematologic malignancy of plasma cells. Differentiating multiple myeloma from the precursor stages of monoclonal gammopathy of undetermined significance and smoldering multiple myeloma is very important because the treatment approach is different for each. The diagnosis is mainly clinical, while the role of imaging is confined to the staging process, assessing response to therapy, and monitoring for disease progression. In this article, we examine the role of different imaging modalities in patients with multiple myeloma.

Serum-free light chains combined with the Revised International Staging System could further distinguish the superior and inferior clinical outcome of multiple myeloma patients

The Revised International Staging System (R-ISS) was introduced as a powerful prognostic system to stratify patients with newly diagnosed multiple myeloma (NDMM). The serum-free light chain (sFLC) has been developed as a valuable marker to monitor multiple myeloma (MM) progression and response. Therefore, it is imperative to combine R-ISS and sFLC prognostic factors as modified R-ISS (MR-ISS) to better stratify patients into homogeneous survival subgroups, especially to further distinguish the high-risk MM patients who are likely to experience rapid progression or relapse. A total of 595 patients with NDMM were studied retrospectively. We performed the K-adaptive partitioning in 595 NDMM patients to define the MR-ISS classification: stage I includes R-ISS stage I and sFLC ratio < 80 (n = 66); stage III includes R-ISS stage III with sFLC ratio ≥ 80 (n = 87); stage II includes all the remaining conditions (n = 442). The median OS was not reached for MR-ISS stage I, 48.67 months for stage II, and 21.13 months for stage III. A significant OS difference of MR-ISS stage I and III patients has a particularly superior and inferior outcome compared with R-ISS stage I and III, respectively, which showed the similar results in PFS analysis. Validation of results was performed in an independent cohort. Our data indicate that the MR-ISS provides an improved prognostic power compared with R-ISS.

Immunoglobulin free light chains as an inflammatory biomarker of heart failure with myocarditis

BACKGROUND

In this study, we measured immunoglobulin free light chains (FLC), a biomarker of inflammation in the sera of patients with heart failure due to myocarditis.

METHODS

FLC kappa and FLC lambda were assayed in stored serum samples from patients with heart failure with myocarditis from the US myocarditis treatment trial by a competitive-inhibition multiplex Luminex® assay.

RESULTS

The median concentration of circulating FLC kappa/lambda ratio was significantly lower in the sera from patients with heart failure with myocarditis than in healthy controls, and FLC kappa/lambda ratio had good diagnostic ability for identification of heart failure with myocarditis. Further, FLC kappa/lambda ratio was an independent prognostic factor for overall survival, and allowed creation of three prognostic groups by combining with N-terminal pro-B-type natriuretic peptide.

CONCLUSIONS

This study suggests that FLC kappa/lambda ratio is a promising biomarker of heart failure with myocarditis.

Development and characterization of polyclonal antibody against human kappa light chain in rabbit

Polyclonal antibodies against kappa light chain are used to diagnose diseases producing free light chain. The kappa and lambda light chains are products of immunoglobulin synthesis and released into the circulation in minor amounts such as serum, cerebrospinal fluid, urine and synovial fluid in normal condition. The purpose of this study was the production and purification of polyclonal immunoglobulin G (IgG) against human kappa light chains. In this study, early human IgG was purified by ion-exchange chromatography, reduced with Dithiothreitol and heavy and light chains were separated with size-exclusion chromatography. Afterward, affinity chromatography with protein L Sepharose at pH 2.00 was displayed to be a dominant condition for the separation and purification of the kappa light chain of immunoglobulins from human serum. Eventually, the rabbit was immunized by human kappa light chains. The rabbit IgG was purified and labeled with horseradish peroxidase (HRP). Direct enzyme-linked immunosorbent assay was planned to determine the titer of HRP conjugated rabbit IgG against the human kappa light chain. The optimum titer of anti-kappa IgG was 1:16000. At the result, purified polyclonal anti-kappa is useful tool in biomedical and biochemical researches and diagnostic kits.

Is urine immunofixation electrophoresis necessary for monitoring myeloma patients who have undergone hematopoietic stem cell transplantation?

INTRODUCTION

To investigate the role of urine immunofixation electrophoresis in detecting relapse in patients with myeloma who have undergone autologous and allogeneic hematopoietic stem cell transplantation (HSCT).

METHODS

The study included a total of 78 patients, comprising 49 males and 29 females, with progressive disease or relapse after HSCT. Serum protein electrophoresis (sPE), serum immunofixation electrophoresis (sIFE) and serum free light chain κ/λ ratio in addition to urine immunofixation (uIFE) were studied.

RESULTS

sPE, sIFE and κ/λ ratio demonstrated relapse in 65.3%, 88.3% and 58.9% of the cases by theirselves respectively. The combination panel of sPE and sIFE demonstrated relapse in 88.3% of patients whereas sPE, sIFE and κ/λ ratio all together demonstrated relapse in 95.8% of the patients. In relapsed patients, urine immunofixation was found to be positive in 16.2% of the patients. No patients with relapsed disease were missed by omitting uIFE from serum studies (sPE, sIFE and sFLC).

CONCLUSION

For evaluation of relapse in MM patients after HSCT, uIFE had no additional diagnostic capability compared to serum studies (sPE, sIFE, and sFLC). Therefore, urine studies should be performed more selectively.

Circulating monocyte subsets in multiple myeloma patients receiving autologous stem cell transplantation - a study of the preconditioning status and the course until posttransplant reconstitution for a consecutive group of patients

BACKGROUND

Induction therapy of multiple myeloma patients prior to autologous stem cell transplantation has changed from conventional chemotherapy to treatment based on proteasome inhibitors or immunomodulatory drugs. We used flow cytometry to analyze total monocyte and monocyte subset (classical, intermediate and non-classical monocytes) peripheral blood levels before and following auto-transplantation for a consecutive group of myeloma patients who had received the presently used induction therapy.

RESULTS

The patients showed normal total monocyte concentrations after induction/stem cell mobilization, but the concentrations of classical monocytes were increased compared with healthy controls. Melphalan conditioning reduced the levels of total CD14⁺ as well as classical and non-classical monocytes, whereas intermediate monocytes were not affected. Thus, melphalan has a non-random effect on monocyte subsets. Melphalan had a stronger effect on total and classical monocyte concentrations for those patients who had received induction therapy including immunomodulatory drugs. Total monocytes and monocyte subset concentrations decreased during the period of pancytopenia, but monocyte reconstitution occurred before hematopoietic reconstitution. However, the fractions of various monocyte subsets varied considerably between patients.

CONCLUSIONS

The total level of circulating monocytes is normalized early after auto-transplantation for multiple myeloma, but pre- and post-transplant levels of various monocyte subsets show considerable variation between patients.

Comparison of two serum free light chain assays for the diagnosis of primary plasma cell malignant proliferative disease

BACKGROUND AND AIMS

The serum free light chain assay (sFLC) is well established for aiding in the diagnosis, prognosis, and monitoring of plasma cell proliferative disorders. There are currently two commercially available sFLC immunoassays, Freelite, based on polyclonal antibody technology, and N Latex FLC, based on monoclonal antibodies. This study aimed to compare the analytical and clinical performance of these two assays in a Chinese population.

METHODS

This study included 74 consecutive patients who were newly diagnosed with monoclonal gammopathies (MGs) including multiple myeloma (MM), AL amyloidosis, and light chain deposition disease (LCDD) between January 2014 and May 2015 at the First Affiliated Hospital of Zhejiang University. Alongside serum and urine electrophoresis analysis, the serum samples were retrospectively tested with both sFLC assays according to the manufacturers' instructions.

RESULTS

The two sFLC assays showed a moderate correlation for κFLC (Passing-Bablok slope = 0.645, coefficient of determination (R 2) = 0.83, and Spearman coefficient = 0.904). However, for λFLC, a poor correlation was found (Passing-Bablok slope = 0.690, R 2 = 0.39, and Spearman coefficient = 0.852). The concordance rate of κFLC, λFLC, and κ/λ FLC ratio were 83.78%, 75.68%, and 86.49%, respectively. The clinical sensitivity of the κ/λ ratios were 83.8% for the Freelite assay and 75.7% for the N Latex FLC assay.

CONCLUSION

Although the concordance and the clinical sensitivity of the two assays appeared comparable, a number of discrepancies were observed. There is a low correlation between the two assays in clinical practice, suggesting that the assays are not equivalent and, thus, current IMWG guidelines, based on Freelite, cannot be cross-applied to N Latex FLC.

Missed Monoclonal Disease Manifesting in Early Post-renal Transplant Period

A 63-year-old diabetic gentleman with microvascular complications presented with advanced azotemia and anemia. He was stabilized with blood transfusion and hemodialysis. With the probable diagnosis of diabetic nephropathy-related end-stage renal disease, he underwent kidney transplantation. He had delayed graft function. Graft biopsy done on the 2^nd postoperative day showed acute tubular necrosis. Graft biopsy repeated after 2 weeks for persistent graft dysfunction showed myeloma cast nephropathy (MCN) and light chain proximal tubulopathy. Work-up for multiple myeloma was positive. He was started on plasmapheresis and chemotherapy. However, he suffered sudden cardiac death during dialysis after 1 week. The presence of MCN in the early graft biopsy implies that it must have been the cause for his native kidney failure. Thus, renal failure in a diabetic should not always be presumed to be due to diabetic nephropathy, and kidney biopsy should be done in diabetics with atypical features.

Double inner standard plot model of an electrophoresis titration chip for a portable and green assay of protein content in milk

High portability and environmental safety ("green") are two of the most important objectives pursued by microfluidic methods. However, there remain many challenges for the design of portable and visual microfluidic methods (e.g., chip electrophoresis) due to use of a cumbersome pump, power supply and detector. Herein, a facile double inner standard plot (DISP) model of electrophoresis titration (ET) was proposed for portable and visual assay of proteins in test milk samples without use of a pump, power supply or detector based on a moving reaction boundary (MRB) chip. The DISP-ET model predicted that: (i) by setting the upper limit (UL) and lower limit (LL) of double inner standard milk protein contents, points U and L were, respectively, achieved in the relationship D = -aC + b (D: MRB motion distance; C: protein content); and (ii) the two points divided both the C-axis and D-axis into "poor", "eligible" and "superior" rulers scaled for quantitative assay of test samples. To demonstrate the model of DISP-ET, an original portable device (120 mm × 78 mm × 30 mm, 341 g) was designed, which had a chip (25 mm × 25 mm × 4 mm) of three channels (15 mm × 200 μm × 80 μm), platinum electrodes, a lithium cell and touch screen. A series of experiments were undertaken based on the developed portable device. The relevant experiments demonstrated systemically the validity of the DISP-ET model, theory and method. In particular, the experiments clearly showed the advantages of the DISP-ET chip: portability, visuality, green use, rapidity, and flexibility for real-life use. Finally, the device was applied for a portable and visual assay of fresh milk from a cow on a dairy farm. The DISP-ET model opens a window for designing portable and visual quantitative methods of food-safety control and clinical diagnoses.

Localized Lichen Myxedematosus With Plasma Cell Light Chain Restriction: Is It the Exception or the Rule?

Lichen myxedematosus is a chronic cutaneous mucinosis that can present on a spectrum from localized cutaneous lesions to systemic disease of scleromyxedema. The clinical presentation of localized cutaneous lichen myxedematosus is waxy lichenoid papules, nodules, and/or plaques that have histopathologic findings of mucin deposition and a variable degree of fibroblast proliferation. There is an absence of serum paraproteins, and there are no other systemic causes of cutaneous mucinosis such as thyroid disease. The pathogenesis of lichen myxedematosus is unknown. We report 3 cases of localized cutaneous lichen myxedematosus with a light chain-restricted plasmacytic component by in situ hybridization. Our findings deliver an insight for disease pathogenesis and highlight for the first time, the significance of plasma cells in lesions of localized cutaneous lichen myxedematosus. We suggest that plasma cell light chain restriction could represent a clue to distinguish localized cutaneous disease from systemic disease.

Association of Monoclonal Gammopathy with Progression to ESKD among US Veterans

BACKGROUND AND OBJECTIVES

Whether patients with monoclonal protein are at a higher risk for progression of kidney disease is not known. The goal of this study was to measure the association of monoclonal protein with progression to ESKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This was a retrospective cohort study of 2,156,317 patients who underwent serum creatinine testing between October 1, 2000 and September 30, 2001 at a Department of Veterans Affairs medical center, among whom 21,898 had paraprotein testing within 1 year before or after cohort entry. Progression to ESKD was measured using linked data from the US Renal Data System.

RESULTS

Overall, 1,741,707 cohort members had an eGFR≥60 ml/min per 1.73 m2, 283,988 had an eGFR of 45-59 ml/min per 1.73 m2, 103,123 had an eGFR of 30-44 ml/min per 1.73 m2 and 27,499 had an eGFR of 15-29 ml/min per 1.73 m2. The crude incidence of ESKD ranged from 0.7 to 80 per 1000 person-years from the highest to lowest eGFR category. Patients with low versus preserved eGFR were more likely to be tested for monoclonal protein but no more likely to have a positive test result. In adjusted analyses, a positive versus negative test result was associated with a higher risk of ESKD among patients with an eGFR≥60 ml/min per 1.73 m2 (hazard ratio, 1.67; 95% confidence interval, 1.22 to 2.29) and those with an eGFR of 15-29 ml/min per 1.73 m2 (hazard ratio, 1.38; 95% confidence interval, 1.07 to 1.77), but not among those with an eGFR of 30-59 ml/min per 1.73 m2. Progression to ESKD was attributed to a monoclonal process in 21 out of 76 versus seven out of 174 patients with monoclonal protein and preserved versus severely reduced eGFR at cohort entry.

CONCLUSIONS

The detection of monoclonal protein provides little information on ESKD risk for most patients with a low eGFR. Further study is required to better understand factors contributing to a positive association of monoclonal protein with ESKD risk in patients with preserved and severely reduced levels of eGFR.

Serum free light chain measurements to reduce 24-h urine monitoring in patients with multiple myeloma with measurable urine monoclonal protein

Detection of myeloma progression (PD) relies on serial 24-h urinary M protein measurements in patients without measurable serum M spike. We examined whether serial difference free light chain (dFLC) levels could be used as a surrogate for serial 24-h urine M protein measurements in monitoring for PD in patients with baseline measurable urine M protein. We studied 122 patients who had serial measurement of urine M protein and serum FLC and had demonstrated PD. The median increase in dFLC with progression as defined by urine M spike was 110% (IQR: 55-312) and median absolute increase was 74 mg/dL; while 89% of patients had dFLC increase ≥ 25%, 94% had absolute increase in dFLC > 10 mg/dL, and 98% met at least 1 of these 2 criteria at PD. In patients with baseline measurable serum FLC (n = 118), 89% had increase in dFLC ≥ 25%, 97% had dFLC increase of > 10 mg/dL, and 98% had 1 of the 2. We conclude that serial dFLC assessments can be used in place of serial 24-h urine protein assessments during myeloma surveillance to monitor for PD. Once patients have an absolute increase in dFLC of >10 mg/dL from the nadir, a 24-h urine collection can then be assessed to document PD as per the International Myeloma Working Group criteria.