Suppression of polyclonal immunoglobulins in multiple myeloma: relationship to the staging and other manifestations at diagnosis

Association Between Immunoparesis and Treatment Outcomes of Patients With Newly Diagnosed Multiple Myeloma: A Systematic Review and Meta-Analysis

BACKGROUND

Immunoparesis, defined as suppression of uninvolved polyclonal immunoglobulins, occurs in up to 80% of patients with newly diagnosed multiple myeloma (NDMM). Infections are the second most common cause of mortality in this population, yet evidence regarding prognostic impact of immunoparesis in NDMM remains unclear.

MATERIALS AND METHODS

Using a prepublished protocol (CRD42022308687), we searched seven bibliographic databases from inception to February 2023 for studies reporting the impact of immunoparesis on clinical outcomes among adults with NDMM. The primary outcome of interest was overall survival (OS) and secondary outcomes were progression free survival (PFS) and infection risk. Effect sizes were quantified in terms of hazards ratio (HR) and pooled across studies using a random effects restricted maximum likelihood method. Heterogeneity was assessed using Cochran Q and the I2 statistic. Publication bias was assessed using contour enhanced funnel plots.

RESULTS

Of 5175 studies screened, 7 studies involving 6091 patients met our search criteria. Immunoparesis was not associated with worse OS (pooled hazard ratio 1.30; 95% CI, 0.91-1.84; P-value .11), with significant heterogeneity among the studies (I2 = 72.9%; Cochran's Q P-value .003). However, immunoparesis was associated with a significantly worse PFS (pooled hazard ratio 1.42; 95% CI 1.11-1.82; p value 0.013), with moderate heterogeneity (I2 statistic = 51%; Cochran's Q P-value .056). Infection rates were not uniformly reported precluding meta-analysis. Visual examination of funnel plot revealed the possibility of publication bias.

CONCLUSION

Overall, our findings suggest that immunoparesis did not have a detrimental impact on OS, but was associated with a significantly shorter PFS. Further studies are needed to understand the complexity of immune system perturbations in NDMM.

Development of a nomogram prognostic model for early Grade ≥ 3 infection in newly diagnosed multiple myeloma based on immunoparesis

BACKGROUND

Infection, a significant cause of death in multiple myeloma (MM) patients, is a common complication and is closely associated with immunoparesis. There exists no clear definition of early infection, so early infection is defined in this paper as the occurrence within 3 months after diagnosis, considering the high incidence of infections within 3 months after diagnosis. This study established a new nomogram model based on immunoparesis to identify MM patients with high-risk early infection.

METHODS

A retrospective collection of 430 NDMM patients from June 2013 to June 2022 was conducted, and the patients were further divided into a training cohort and a validation cohort. In the training cohort, the least absolute shrinkage and selection operator (LASSO) was used to select the best variables that can be used to establish a new nomogram prediction model. Validation was performed in the validation and entire cohorts.

RESULTS

After diagnosis, 67.7 % of the patients suffered from severe infection within 1 year, and 59.5 % experienced the first severe infection within 3 months. Variables associated with an increased risk of severe infection in the first 3 months included: BMPC, D-dimer, serum β2 microglobulin, immunoparesis, albumin, and eGFR. The nomogram based on the above six factors achieved a good C-index of 0.754, 0.73, and 0.731 in predicting early infection in the training cohort, validation cohort, and entire cohort, respectively. Finally, the time-dependent receiver operating characteristic (ROC) curve and decision curve analysis (DCA) of the nomogram showed that the model provided superior diagnostic capacity and clinical net benefit.

CONCLUSION

In this study, we established a nomogram model to predict early grade ≥ 3 infection in NDMM patients. This model can assist clinicians in identifying NDMM patients with high-risk infections and improve their prognosis through early intervention.

Clinical Considerations for Immunoparesis in Multiple Myeloma

Simple Summary

Immunoparesis in multiple myeloma is defined as the suppression of one or more of the uninvolved immunoglobulins, AKA, polyclonal immunoglobulin. The extent of immunoparesis is an independent prognostic factor in patients with newly diagnosed multiple myeloma. Myeloma patients with suppressed uninvolved immunoglobulins at diagnosis have shorter median overall survival (OS) and progression-free survival (PFS). This review article summarizes immunoparesis in myeloma patients, contributing factors, its impact on myeloma progression, general outcomes, and infectious complications.

Abstract

Multiple myeloma is a relatively common clonal plasma cell disorder, comprising 17% of hematologic malignancies. One of the hallmark features of this disease is immunoparesis, which is characterized by the suppression of immunoglobulin polyclonality. Though not entirely elucidated, the mechanism behind this process can be attributed to the changes in the tumor microenvironment. All treating clinicians must consider potential complications related to immunoparesis in the management of multiple myeloma. Though not explicitly described in large data series, the increased risk of infection in multiple myeloma is likely, at least in part, due to immunoglobulin suppression. Additionally, the presence of immunoparesis serves as a prognostic factor, conveying poorer survival and a higher risk of relapse. Even in the era of novel agents, these findings are preserved, and immunoglobulin recovery also serves as a sign of improved outcome following autologous HSCT. Though not within the diagnostic criteria for multiple myeloma, the presence and degree of immunoparesis should be at diagnosis for prognostication, and immunoglobulin recovery should be tracked following myeloablative therapy and autologous HSCT.

Combined immune score predicts the prognosis of newly diagnosed multiple myeloma patients in the bortezomib-based therapy era

To investigate the effect of a combined immune score including the lymphocyte-to-monocyte ratio (LMR) and uninvolved immunoglobulin (u-Ig) levels on the prognosis of newly diagnosed multiple myeloma (NDMM) patients treated with bortezomib.Clinical data of 201 NDMM patients were retrospectively analyzed. Patients with LMR ≥ 3.6 and LMR < 3.6 were scored 0 and 1, respectively. Patients with preserved u-Ig levels, suppression of 1 u-Ig, and suppression of at least 2 u-Igs were scored 0, 1, and 2, respectively. The immune score, established from these individual scores, was used to separate patients into good (0-1 points), intermediate (2 points), and poor (3 points) risk groups. The baseline data, objective remission rate (ORR), whether receive maintenance treatment regularly and overall survival of patients before treatment were analyzed.The ORR of the good-risk group was significantly higher than that of the intermediate-risk group (75.6% vs 57.7%, P = .044) and the poor-risk group (75.6% vs 48.2%, P = .007). The multivariate analysis results showed that age ≥ 65 years, International Staging System stage III, platelet count ≤ 100 × 109/L, lactate dehydrogenase (LDH) > 250 U/L, serum calcium > 2.75 mmol/L, no receipt of regular maintenance treatment, LMR < 3.6, suppressed u-Igs = 1, suppressed u-Igs ≥ 2, intermediate-risk group and poor-risk group were independent predictors of poor overall survival.In the bortezomib era, the LMR, u-Ig levels, and the immune score play an important role in the prognosis of NDMM patients. Among them, the immune score showed the strongest prognostic value, and it could be a beneficial supplement for the early identification of high-risk patients.

Treatment Strategy for Multiple Myeloma to Improve Immunological Environment and Maintain MRD Negativity

Improving the immunological environment and eradicating minimal residual disease (MRD) are the two main treatment goals for long-term survival in patients with multiple myeloma (MM). Immunomodulatory drugs (IMiDs), monoclonal antibody drugs (MoAbs), and autologous grafts for autologous stem cell transplantation (ASCT) can improve the immunological microenvironment. ASCT, MoAbs, and proteasome inhibitors (PIs) may be important for the achievement of MRD negativity. An improved immunological environment may be useful for maintaining MRD negativity, although the specific treatment for persistent MRD negativity is unknown. However, whether the ongoing treatment should be continued or changed if the MRD status remains positive is controversial. In this case, genetic, immunophenotypic, and clinical analysis of residual myeloma cells may be necessary to select the effective treatment for the residual myeloma cells. The purpose of this review is to discuss the MM treatment strategy to "cure MM" based on currently available therapies, including IMiDs, PIs, MoAbs, and ASCT, and expected immunotherapies, such as chimeric antigen receptor T cell (CAR-T) therapy, via improvement of the immunological environment and maintenance of MRD negativity.

Clinical significance of the lymphocyte-to-monocyte ratio in multiple myeloma patients with negative minimal residual disease: a single-center retrospective analysis

Minimal residual disease (MRD) is a surrogate marker for survival in multiple myeloma (MM), while the lymphocyte-to-monocyte ratio (LMR) is a prognostic factor associated with the patients' immunological status. We retrospectively evaluated the clinical impact of MRD negativity and LMR. MRD was analyzed by multicolor flowcytometry (threshold, 1 × 10-5). Fifty-eight patients (median age 70 years) who achieved complete response were included in this study. Twenty-two patients received autologous stem cell transplantation, 14 received daratumumab-based chemotherapy, and 22 received another treatment. Forty-one (70.7%) patients achieved MRD negativity. Over the median follow-up time of 15.1 months, PFS in MRD-negative patients was significantly longer than in MRD-positive patients (P = 0.020). In addition, a high LMR at MRD assessment was associated with MRD negativity (P = 0.019) and long PFS (P = 0.009). Finally, neither MRD negativity nor high LMR at MRD assessment was associated with significantly shorter PFS compared with MRD positivity or low LMR (P = 0.002). In conclusion, high LMR was associated with MRD negativity and can be used as a predictor of long PFS. Change of treatment strategy might be essential for patients with MRD positivity and high LMR at MRD assessment due to their short PFS.

Efficacy of Intravenous Immunoglobulin for Preventing Infections in Patients with Multiple Myeloma

INTRODUCTION

Despite many recent advances in the treatment of multiple myeloma (MM), infection remains a major cause of morbidity and mortality. Prior studies have shown mixed results using intravenous immunoglobulin (IVIG) to prevent infections in MM and were conducted prior to most modern MM therapies.

PATIENTS AND METHODS

We retrospectively reviewed all patients with MM treated with IVIG at our institution from 2010 to 2017. The primary endpoint was the incidence rate ratio (IRR) of infectious events (IEs) per patient-year during IVIG versus observation.

RESULTS

A total of 68 patients were included; 151 IEs occurred during 918 months of IVIG treatment, whereas 446 IEs occurred during 2484 months of observation. Although the annual rate of IEs was substantially higher during periods of progressive disease (PD) compared with non-PD (4.9 vs. 1.8; P < .001), most IEs occurred during periods of non-PD (75% vs. 25% during PD). There was no overall difference in the annual rate of IEs per patient between IVIG and observation (1.97 vs. 2.16; IRR, 0.92; 95% confidence interval [CI], 0.76-1.10; P = .376). The subgroup of patients with hypogammaglobulinemia and whose myeloma was in a non-PD phase had a significant reduction in all-grade IEs (1.20 vs. 1.92; IRR, 0.63; 95% CI, 0.45-0.88; P = .009) and ≥ grade 3 IEs (0.25 vs. 0.56; IRR, 0.45; 95% CI, 0.22-0.94; P = .041) with IVIG compared with observation.

CONCLUSION

Although treatment with IVIG did not show benefit in the overall population, there may be subgroups of patients that derive significant benefit. Additional observational studies are needed to confirm these findings and further refine patient selection.

Anti-bacterial antibodies in multiple myeloma patients at disease presentation, in response to therapy and in remission: implications for patient management

Multiple myeloma (MM) is associated with increased risk of infection, but little is known regarding antibody levels against specific bacteria. We assessed levels of polyclonal immunoglobulin and antibacterial antibodies in patients recruited to the TEAMM trial, a randomised trial of antibiotic prophylaxis at the start of anti-myeloma treatment. Polyclonal IgG, IgA and IgM levels were below the reference range in 71%, 83% and 90% of 838 MM patients at diagnosis. Anti-vaccine targeted tetanus toxoid antibodies were protective in 95% of 193 healthy controls but only 41% of myeloma patients. In healthy controls, protective antibodies against 6/12 pneumococcal serotypes, haemophilus and meningococcus A were present in 67%, 41% and 56% compared to just 15%, 21% and 17% of myeloma patients. By 1 year, myeloma patients IgG levels had recovered for 57% of patients whilst the proportion with protective levels of IgG against thymus-dependent protein antigen tetanus toxoid had changed little. In contrast the proportions of patients with protective levels against thymus independent polysaccharide antigens pneumococcus, haemophilus and meningococcus had fallen from 15 to 7%, 21 to 0% and 17 to 11%. Findings highlight the need for strategies to protect patients against bacterial infections during therapy and vaccination programmes during remission.

Characterisation and prognostic impact of immunoparesis in relapsed multiple myeloma

Characterisation and prognostic impact of immunoparesis in relapsed multiple myeloma (MM) is lacking in the current literature. We evaluated 258 patients with relapsed MM, diagnosed from 2008 to 2015, to investigate the prognostic impact of deep immunoparesis on post-relapse survival. On qualitative immunoparesis assessment, no, partial and full immunoparesis was present in 9%, 30% and 61% of patients, respectively. Quantitative immunoparesis was assessed by computing the average relative difference (ARD) between polyclonal immunoglobulin(s) and corresponding lower normal limit(s), with greater negative values indicating deeper immunoparesis. The median ARD was -39%, with an optimal cut-off of -50% for overall survival (OS) by recursive partitioning analysis. Deep immunoparesis (ARD ≤-50%) was associated with a higher tumour burden at first relapse compared to none/shallow [ARD >-50%] immunoparesis. The OS (P = 0·007) and progression-free survival (PFS; P < 0·001) differed significantly between the deep and none/shallow immunoparesis groups. Kaplan-Meier estimates for 3-year OS were 36% and 46%, and for 2-year PFS were 17% and 27%, respectively. On multivariable analysis (MVA) for PFS, both qualitative and quantitative immunoparesis retained negative prognostic impact independently. However, only quantitative immunoparesis was independently prognostic for OS on MVA. Depth of immunoparesis in relapsed MM is an important prognostic factor for post-relapse survival in the era of novel agents and continuous therapy.

Combined immune score of lymphocyte to monocyte ratio and immunoglobulin levels predicts treatment-free survival of multiple myeloma patients after autologous stem cell transplant

Outcomes after ASCT are highly variable making it difficult to predict risk of disease progression. We analyzed the impact of clinically available immune-related biomarkers on treatment-free survival (TFS) in 130 patients receiving Mel200 and ASCT. Absolute lymphocyte count (ALC), monocyte count (AMC), neutrophil count (ANC), and immunoglobulin (Ig) levels were collected on day -2 and 90 of ASCT. The lymphocyte-monocyte (LMR) and neutrophil-lymphocyte ratios (NLR) were then derived. At Day +90, we found that low ALC (18 versus 23 months, p = 0.04) or AMC (13 versus 25 months, p = 0.02) predicted for worse TFS. A low LMR predicted for worse TFS (16 versus 52 months, p = 0.004). Patients with two or three suppressed Ig levels had worse TFS (17 versus 51 months, p = 0.04). Median TFS for poor (low LMR and 2-3 suppressed Ig), intermediate, and good (high LMR and 0-1 suppressed Ig) risk groups was 7.5 versus 27 versus 79 months, respectively (p = 0.0004). In a multivariate analysis, a low LMR and suppressed Ig levels were strong independent predictors of poor TFS. We propose an immune score combining these available tests to stratify patients at risk for early progression and identify those who may benefit from intensified post-ASCT consolidation or immunotherapy based approaches.

Immunoparesis recovery 1 year after ASCT is independently associated with favorable survival in patients with symptomatic multiple myeloma who undergo autologous stem cell transplantation

Immunoparesis is defined as a reduction in the levels of one, two, or three uninvolved immunoglobulins. However, there are very limited data on the incidence and prognostic significance of immunoparesis recovery 1 year after autologous stem cell transplantation (ASCT) in MM. We reviewed medical records of de novo MM patients who received ASCT at Beijing Chao Yang hospital. One hundred eight MM patients were included in the study. Conventional chemotherapy was administered as induction regimen in 16 patients (14.8%), whereas novel agents were used in 92 patients (85.2%). Most patients had immunoparesis at diagnosis (89.1%) and at the moment of ASCT as well (75%). After a median follow-up of 49 months, in the group with immunoglobulin recovery 1 year after ASCT, there was a trend towards longer progression-free survival (PFS) than in the group with immunoparesis (P = 0.054). And overall survival (OS) was significantly longer in patients with immunoparesis recovery (P = 0.004). In multivariate analysis, immunoparesis recovery 1 year after ASCT was independently associated with improved OS (P = 0.016). In conclusion, lack of immunoparesis recovery 1 year after ASCT in MM patients is associated with significantly shorter OS and this group of patients needs new treatment strategy to improve the prognosis.

Characterisation of immunoparesis in newly diagnosed myeloma and its impact on progression-free and overall survival in both old and recent myeloma trials

We measured immunosuppression at myeloma diagnosis and assessed the impact on survival in 5826 UK myeloma trial patients. Polyclonal immunoglobulin levels were below normal in 85% of patients and above normal in only 0.4% of cases for IgA, 0.2% for IgM and no cases for IgG. Immunoparesis had a greater impact in recent trials: median overall survival (OS) was up to 3 years longer for patients without immunoparesis compared to the old trials, less than 1 year longer. Median progression-free survival (PFS) was 39%, 36% and 57% longer for patients with normal IgG, IgA and IgM levels, respectively. The depth of IgM suppression, but not the depth of IgG or IgA suppression, was prognostic for survival: the most severely suppressed IgM tertile of patients OS was 0.9 years shorter than those in the top tertile, and 2.6 years shorter than OS of those with normal IgM levels (p = .007). The degree of suppression of polyclonal IgM levels below normal was associated with worse PFS (p = .0002). Infection does not appear to be the main mechanism through which immunoparesis affects survival. We hypothesise that IgM immunoparesis impacts through a combination of being associated with more aggressive disease and reduced immune surveillance against relapse.

Prognostic impact of immunoparesis at diagnosis and after treatment onset in patients with light-chain amyloidosis

OBJECTIVES

Immunoparesis (IP) is a risk factor associated with an unfavourable outcome in several plasma cell disorders. It has been suggested that its presence in light-chain (AL) amyloidosis could be associated with worse prognosis. However, the relevance of IP after treatment has not been evaluated to date. The aim of this study was to determine the prognostic impact of IP at diagnosis and one year after treatment onset in patients with AL amyloidosis.

METHODS

The clinical records of 69 patients with AL amyloidosis treated at a single institution from January 2006 to January 2016 were included in the study.

RESULTS

IP was observed in 27.5% of patients at diagnosis. The presence of IP was associated with a lower probability to achieve very good partial response or better after first-line treatment (37.8% versus 62.2%; p = .04). However, only in the group of patients treated with autologous stem cell transplantation (ASCT), the presence of IP resulted in a shorter progression-free survival (PFS) (30.2 months versus not reached [NR]; p = .02) but not in overall survival (OS). Persistence of IP at one year after treatment onset was identified in only four (9.8%) of the 41 evaluable patients. In the ASCT group, the absence of IP at one year after treatment onset resulted in a longer median PFS and OS (NR versus 22.6 months; p = .006; and NR versus 35.2 months; p < .001; respectively). In the multivariate analysis, the absence of IP at one year after treatment onset was independently associated with longer survival.

CONCLUSION

IP at diagnosis has a negative impact on survival while its absence at one year after treatment is an independent marker for long-term survival.

Active multiple myeloma suppresses and typically eliminates coexisting MGUS

Background:

Myeloma is consistently preceded by premalignant monoclonal gammopathy of undetermined significance (MGUS). In >5% of MGUS patients there is a second MGUS clone (biclonal gammopathy of undetermined significance; BGUS), yet, at myeloma diagnosis, presentation of biclonal gammopathy myeloma (BGMy) is considered less frequent, implying that myeloma eradicates coexisting MGUS.

Methods:

In the largest study of its kind, we assessed BGMy frequency amongst 6399 newly diagnosed myeloma patients enrolled in recent UK clinical trials.

Results:

Compared to expected prevalence (i.e., >5% of MGUS have BGUS), only 58 of 6399 (0.91%) newly diagnosed myeloma patients had BGMy, indicating myeloma typically eliminates coexistent MGUS. In these 58 BGMy cases, the MGUS plasma cell clone was greatly suppressed in size compared to typical levels observed in conventional MGUS; contrarily, the MGUS clone did not inhibit the myeloma plasma cell clone in BGMy.

Conclusion:

Myeloma eliminates the majority of competing MGUS, and when it does not, the MGUS clone is substantially reduced in size.

The Effect of Suppressed Levels of Uninvolved Immunoglobulins on the Prognosis of Symptomatic Multiple Myeloma

Objective:

The majority of multiple myeloma (MM) patients have high levels of monoclonal immunoglobulin in the serum and/or urine and suppressed levels of the uninvolved immunoglobulins. The prognostic significance of this phenomenon has not been assessed sufficiently. In this study, our aim is to evaluate the prognostic significance of uninvolved immunoglobulin suppression measured by nephelometry in patients with new symptomatic MM and the association with other features of the disease.

Materials and Methods:

Between August 2003 and February 2015, 137 patients who were referred for the treatment of newly diagnosed symptomatic myeloma to the Hematology Department polyclinics of the İstanbul University İstanbul Faculty of Medicine were prospectively included and had available pretreatment immunoglobulin levels measured by nephelometry.

Results:

Suppression of at least one uninvolved immunoglobulin was observed in 87% of patients and this situation was slightly more common in patients with immunoglobulin A myeloma but had no statistical significance (p>0.05). Uninvolved immunoglobulin suppression was also more common among patients who had bone marrow plasma cell infiltration of ≥40% and presented with anemia and hypercalcemia (p<0.05). The overall survival time was shorter in patients with positive calcium-renal-anemia-bone criteria and International Staging System stage 3 compared with others (p<0.05). Factors that were independently associated with inferior survival in the multivariate analysis included patients with estimated glomerular filtration rate of <60 mL/min, age of >65 years, lactate dehydrogenase of >300 IU/L, bone marrow plasma cells of ≥40%, and β2-microglobulin of >3.5 mg/dL (p<0.05).

Conclusion:

In this study, 13.1% of MM patients had preserved levels of uninvolved immunoglobulins. We observed that patients who had preserved uninvolved immunoglobulin levels had better treatment responses and better pathologic signs, but statistical significance could not be shown. Conversely, patients with suppression of even one of the uninvolved immunoglobulins had a shorter survival, but similarly, statistical significance could not be shown.

Pretreatment Lymphopenia, Poor Performance Status, and Early Courses of Therapy Are Risk Factors for Severe Bacterial Infection in Patients with Multiple Myeloma during Treatment with Bortezomib-based Regimens

The aim of this study was to identify the risk factors associated with severe bacterial infection (SBI) in multiple myeloma (MM) patients during treatment with bortezomib-based regimens. A total of 98 patients with MM were evaluated during 427 treatment courses. SBI occurred in 57.1% (56/98) of the patients and during 19.0% (81/427) of the treatment courses. In the multivariate analysis for the factors associated with the development of SBI in each treatment course, poor performance status (Eastern Cooperative Oncology Group ≥ 2, P < 0.001), early course of therapy (≤ 2 courses, P < 0.001), and pretreatment lymphopenia (absolute lymphocyte count < 1.0 × 10(9)/L, P = 0.043) were confirmed as independent risk factors. The probability of developing SBI were 5.1%, 14.9%, 23.9% and 59.5% in courses with 0, 1, 2, and 3 risk factors, respectively (P < 0.001). In conclusion, we identified three pretreatment risk factors associated with SBI in each course of bortezomib treatment. Therefore, MM patients with these risk factors should be more closely monitored for the development of SBI during bortezomib-based treatment.

Infectious complications in patients with newly diagnosed multiple myeloma: A complication from the past?

Infectious complications are an important risk factor for early mortality in patients with multiple myeloma. However, data about the impact and severity of infections in these patients in the era of new therapies have not been properly analyzed. This review has reviewed the incidence and severity of infections complications and infection-related mortality during induction treatment in patients with newly diagnosed myeloma receiving regimens with new drugs within randomized trials. The results show that infections are still a major cause of morbidity, especially among elderly patients receiving immunomodulatory drugs seen in up to 28% of patients in some trials vs less than 10% among transplant-eligible patients. Overall infection-related mortality ranged from 0-7% in transplant-ineligible patients, with no infection-related deaths in the majority of the trials including younger patients. Strategies directed to further reduce these complications and a better knowledge of their impact in patients treated outside clinical trials are needed.

Preserved levels of uninvolved immunoglobulins are independently associated with favorable outcome in patients with symptomatic multiple myeloma

Suppression of uninvolved immunoglobulins is common in multiple myeloma (MM) but the prognostic significance of this phenomenon has not been assessed. We evaluated the prognostic significance of the preservation of uninvolved immunoglobulins in 1755 consecutive, unselected, patients with newly diagnosed, symptomatic MM with pre-therapy immunoglobulin levels measured by nephelometry. Suppression of at least one uninvolved immunoglobulin was observed in 87% of patients and was more common in patients with immunoglobulin A myeloma, those aged over 65 years, in patients with advanced-International Staging System (ISS) stage, extensive-bone marrow infiltration, anemia, low platelet counts, high levels of serum M-monoclonal protein or renal dysfunction. Patients with preserved immunoglobulins had a better survival than patients with suppressed immunoglobulins (median survival 55 vs 41.5 months, P<0.001). In multivariate analysis, preservation of uninvolved immunoglobulins was independently associated with better survival (hazard ratio: 0.781, 95% confidence interval: 0.618-0.987, P=0.039); irrespective of the treatment. In a subset of 500 patients, which were strictly followed for disease progression, preservation of uninvolved immunoglobulins was associated with a significantly longer progression-free survival (60 vs 25 months, P<0.001), independently of other common prognostic factors. In conclusion, preservation of uninvolved immunoglobulins in newly diagnosed patients with symptomatic MM was independently associated with long term disease control and improved survival.

Changing treatment paradigms for patients with plasma cell myeloma: impact upon immune determinants of infection

Plasma cell myeloma (PCM) is increasing in prevalence in older age groups and infective complications are a leading cause of mortality. Patients with PCM are at increased risk of severe infections, having deficits in many arms of the immune system due to disease and treatment-related factors. Treatment of PCM has evolved over time with significant impacts on immune function resulting in changing rates and pattern of infection. Recently, there has been a paradigm shift in the treatment of PCM with the use of immunomodulatory drugs and proteasome inhibitors becoming the standard of care. These drugs have wide-ranging effects on the immune system but their impact on infection risk and aetiology remain unclear. The aims of this review are to discuss the impact of patient, disease and treatment factors on immune function over time for patients with PCM and to correlate immune deficits with the incidence and aetiology of infections seen clinically in these patients. Preventative measures and the need for clinically relevant tools to enable infective profiling of patients with PCM are discussed.

Multiple myeloma--an update on diagnosis and treatment

Multiple myeloma is a plasma cell (PC) malignancy characterized by the accumulation of monoclonal PCs in the bone marrow and the production of large amounts of a monoclonal immunoglobulin or paraprotein. In the past years, new approaches in the diagnosis and treatment were introduced aiming to identify high-risk patients who need proper anti-myeloma treatment. Intensive therapy including autologous hematopoietic stem cell transplantation and the new agents bortezomib, thalidomide, and lenalidomide have improved patients' responses. Further optimalization of the different treatment schedules in well-defined patient groups may prolong their survival. Patient stratification is currently based on patient characteristics, extent of myeloma disease, and associated cytogenetic and laboratory anomalies. More and more gene expression studies are introduced to stratify patients and to individualize therapy.

Polyclonal immunoglobulin E levels are correlated with hemoglobin values and overall survival in patients with multiple myeloma

PURPOSE

Polyclonal IgG, IgA, and IgM immunoglobulins are often decreased in sera of patients with multiple myeloma (MM), whereas very few data are available on polyclonal IgE levels. We have determined IgE levels in a large series of MM patients at diagnosis and subjects with monoclonal gammopathy of undetermined significance (MGUS) and correlated IgE levels with survival and prognostic factors in MM.

EXPERIMENTAL DESIGN

IgE were determined with a commercially available ELISA kit in 201 MM patients at diagnosis, 144 subjects with MGUS, and 77 age-matched controls.

RESULTS

IgE levels progressively decreased from controls to MGUS and from MGUS to MM (P = 0.001). MM patients with IgE levels of >11.5 IU/mL (median) had a better survival than patients with IgE of <11.5 IU/mL (P = 0.048). The difference was even more significant when MM patients were divided according to clinical cutoff values. Patients with elevated IgE levels (>100 IU/mL) had from 2 to 3 years longer survival than those with low (<10 IU/mL) or intermediate values (10-100 IU/mL; P < 0.01). IgE levels were positively and negatively correlated with hemoglobin (P = 0.006) and beta2-microglobulin levels (P = 0.007), respectively. Univariate and multivariate analyses confirmed that high IgE levels are positive predictors of overall survival (P = 0.03 and 0.08, respectively) and strongly correlated with hemoglobin values.

CONCLUSIONS

Because IgE levels are dependent on Th(2) responses, these data open new perspectives in the interpretation of antitumor immune responses and pathogenesis of anemia in MM.

Circulating clonotypic B cells in the biology of multiple myeloma: speculations on the origin of myeloma

The population of circulating B cells in myeloma patients includes an apparently large but variable subset with the IgH VDJ rearrangement diagnostic for the malignant clone of plasma cells in individual myeloma patients. Although the biological significance is at present unknown, it is likely that they include both malignant and non-malignant clonal relatives of the myeloma plasma cells. This article presents speculations on the significance of these cells in the origin of myeloma and the relationship between monoclonal gammopathy of undetermined significance (MGUS) and frank myeloma. MGUS appears to represent the establishment of clonal dominance probably by a chronically antigen-stimulated B cell clone. It seems likely that malignant transformation event(s) occurring in a clonal daughter cell give rise to myeloma. If correct, this implies that in a myeloma patient, non-malignant antigen-responsive B cells expressing the patient-specific IgH rearrangement coexist in the circulation and probably all lymphoid tissues, with their malignant antigen-independent relatives. However, the significance one attributes to the clonotypic B cells detected in the blood of myeloma patients depends in part on the view one takes of the progression from MGUS to myeloma. An alternative perspective is that MGUS represents a dormant state of malignancy held in check by controlled apoptosis, arrested cell cycling, and/or by immunoregulatory networks. Although lacking in experimental support, if this interpretation were correct, myeloma would occur when the regulatory mechanisms fail, allowing uncontrolled malignant cell renewal. This alternative view would imply that the majority of circulating clonotypic B cells might be malignant. Thus, an analysis of the biology of these clonotypic circulating B cells, with an emphasis on measures of malignancy, is likely to shed considerable light on the events underlying myeloma genesis, progression and spread.

Presenting features of monoclonal gammopathies: an analysis of 684 newly diagnosed cases. Cooperative Group for the Study and Treatment of Multiple Myeloma

OBJECTIVES

The clinical, laboratory and radiologic features at diagnosis of 684 newly diagnosed patients with monoclonal gammopathy were revised in order to underline the differences between monoclonal gammopathies of undetermined significance (MGUS) and stage I multiple myeloma (MM).

DESIGN

Patients were screened for inclusion in a prospective controlled protocol for treatment of MM. Those having serum or urine monoclonal component (MC) were diagnosed as MM when they demonstrated osteolysis and/or bone marrow plasma cells (BMPC) > 20%; patients not fulfilling these criteria were considered MGUS.

SETTING

Patients were recruited from 24 general or university hospitals from the departments of internal medicine, haematology and medical oncology.

SUBJECTS

Seven-hundred-and-fifty were enrolled between January 1986 and March 1990; 684 (343 MGUS and 341 MM) were able to be evaluated for this study and 78 were stage I MM.

INTERVENTIONS

Complete clinical, radiologic and laboratory work-up was carried out at the referral centres.

MAIN OUTCOME MEASURES

The main outcome expected was the confirmation that BMPC > 20% could reliably differentiate stage I MM from MGUS.

RESULTS

At a median follow-up of 36 months (minimum follow-up: 18 months), MGUS had a lower progression rate to overt MM, longer overall survival and different causes of death than stage I MM. Further differences concerned erythrocyte sedimentation rate (28 vs. 47, P < 0.001), per cent reduction of normal immunoglobulin (86 vs. 60%, P < 0.001), serum MC (1.6 vs. 2.2 g dl-1, P < 0.001) and thymidine kinase level (3.3 vs. 4.5 mU ml-1, P < 0.05).

CONCLUSIONS

The study suggests that 20% BMPC can be taken as a safe cut-off point at which to differentiate MGUS from early MM and outlines a few simple parameters which can be of diagnostic aid.

Effects of cefodizime on non-specific immune functions in patients with multiple myeloma

The effects of cefodizime (CDZ) on non-specific immunity in patients with multiple myeloma were studied in a randomized, placebo-controlled trial. A total of 51 patients with newly diagnosed multiple myeloma were admitted to the study, 27 of whom received CDZ 2 gi.v. once daily for seven days and 24 ascorbic acid 1 g daily i.v. for one week. Granulocyte chemotaxis, neutrophil biochemiluminescence and phagocytosis were determined at baseline, and at 48 h after the last dose. At baseline, chemiluminescence, phagocytosis and, to a lesser extent, granulocyte chemotaxis were diminished in both patient groups compared to healthy volunteers. After treatment, a significant increase in chemiluminescence and phagocytosis was observed in the CDZ group, while a slight increase in granulocyte chemotaxis did not reach statistical significance. No changes were observed in the control group. It is concluded that CDZ enhanced non-specific immune mechanisms in patients with multiple myeloma.

Electrophoresis and densitometry of serum and urine in the investigation and significance of monoclonal immunoglobulins

About 15% of monoclonal components or paraproteins are associated with malignancy when detected by simple electrophoresis on cellulose acetate membranes or agarose gel followed by protein staining. More sensitive methods for detecting monoclonal components result in a lower frequency of association with recognisable underlying disease. The sensitivity is dependent on the system used. Isoelectric focusing is 10 to 40 times more sensitive than simple electrophoresis at detecting monoclonal components. Electrophoretically separated bands may be quantitated densitometrically and at the present time this is the most satisfactory method for measuring monoclonal component concentration. Immunochemical methods for quantitating monoclonal components are limited by failure to react in a similar manner to polyclonal standards and giving problems of antigen excess resulting both in falsely elevated and low results. Electrophoretic methods must always be used in conjunction with these. The normal polyclonal ratio of immunoglobulin kappa:lambda light chain is disturbed by the presence of a monoclonal component. In 260 patients with myeloma we found that serum electrophoresis alone detected 90% while a disturbance in the kappa:lambda ratio detected 98%. However, 50% of monoclonal components less than 3 g/L were missed. Log kappa:lambda ratio correlates well with the densitometric scan of monoclonal components, both in vitro and in patients being monitored for treatment response in myeloma. This approach may complement or even replace densitometry for this purpose in the future.

Comparative analysis of immunodeficiency in patients with monoclonal gammopathy of undetermined significance and patients with untreated multiple myeloma

The objectives of this study were firstly, to compare the immunophenotype of patients with monoclonal gammopathy of undetermined significance (MGUS) with that of patients with newly diagnosed, untreated multiple myeloma (Unt. MM). Our second objective was to determine which variables might distinguish patients with MGUS and early MM. The CD4/CD8 ratio in both patient groups differed significantly from normal as a result of a decrease in the proportion of CD4+ cells. Similarly, surface immunoglobulin-positive (Ig+) B cells were significantly reduced in both groups. Also, some impairment of Ig secretion was observed. An in vitro specificity study of B cells showed an enriched proportion of B cells specific for tetanus toxoid (which may be indicative of enrichment for memory B cells) in both MGUS and Unt. MM patients. Further to this, in MM patients but not in MGUS patients, there was an enriched proportion of B cells specific for determinants on the F(ab')2 fragment of Ig. This suggests an anomalous auto-immune reactivity to polyclonal Ig molecules. In one of the two patients studied, who progressed from MGUS to MM, disease progression was accompanied by an increase in this anti-Ig reactivity. In both patients there was a decrease in CD4/CD8 ratio.

B lymphocyte function in multiple myeloma: analysis of T cell- and monocyte-dependent antibody production

T-cell and B-cell functions were studied in 35 patients with untreated multiple myeloma (MM) and in 16 patients with MM treated with prednisolone, melphalan and vincristine. The numbers of CD4+ T cells were normal in untreated MM patients, but markedly decreased in treated patients, whereas CD8+ cell numbers were normal in untreated and treated patients. Mitogen-induced as well as antigen-induced lymphocyte proliferative responses were reduced, but not further affected by treatment. The antigen-induced proliferative responses by lymphocytes of treated, but not of untreated patients, correlated positively to the proportions of CD4+ cells among MNC. Taken together, the findings suggest selective loss of CD4+ subpopulations during cytotoxic treatment. Pokeweed mitogen (PWM)-induced Ig production was generally low, but significantly reduced Ig production was only seen in experiments employing MM B cells and monocytes co-cultured with irradiated T-enriched cells. Irradiated MM T cells displayed normal helper function when co-cultured with normal B cells stimulated with PWM. MM B cells and monocytes cultured with irradiated normal T cells produced little Ig; however, MM monocytes were not suppressive. In 2 of 3 patients with either IgG-kappa or IgA-kappa myeloma, the numbers of PWM-stimulated B cells that produced kappa chains were somewhat higher than those found among normal MNC. The impaired ability of antibody production by B cells from untreated MM patients seems to relate to intrinsic B cell defect(s) rather than to abnormal regulation by T cells or monocytes. However, disturbances in the functions of CD4+ cells may be observed in treated MM.

Differential diagnosis of monoclonal gammopathy

With a large segment of the adult population now undergoing routine screening tests on a periodic basis, findings such as rouleaux when the complete blood count is performed or an elevated total protein and globulin fraction on serum chemistries often lead to the performance of a serum protein electrophoresis. When a monoclonal gammopathy is confirmed, the clinician is faced with a broad differential diagnosis that includes a variety of distinct malignant plasma cell disorders and lymphoproliferative diseases, as well as the high incidence of MGUS in the otherwise healthy adult population. Other benign causes of secondary monoclonal gammopathy, such as underlying inflammatory or infectious disorders or drug reactions, may add to the diagnostic dilemma in some patients. By following a systematic plan of laboratory evaluation such as that described here, however, and always keeping the patient's clinical status as a primary focus, the clinician should be able to arrive at a diagnosis and formulate a therapeutic plan in most instances. The most common differential diagnosis, that of MGUS versus PCM, still is difficult in some cases, and it is emphasized that careful follow up over time remains the best method at present for differentiating these two conditions. Once the basic laboratory evaluation of monoclonal gammopathy has been completed, further work-up will need to be individualized. In some cases, the preliminary evaluation will reveal a key feature, such as a monoclonal gammopathy that is IgM, which will lead to a rapid diagnosis of WMG and alert the clinician to investigate other nonroutine aspects of the laboratory evaluation, such as a serum viscosity or specific tests of hemostatic function. In other patients, the initial laboratory evaluation of monoclonal gammopathy may lead to other recommendations, such as lymph node biopsy for evaluation of possible lymphoma, or tissue biopsy to confirm the suspicion of amyloidosis. Overall, the evaluation of monoclonal gammopathy remains a challenging one, but one in which the clinician usually is rewarded with a diagnosis that will allow him to make appropriate management plans for his patient.

Humoral immune deficiency in multiple myeloma patients due to compromised B-cell function

Patients with multiple myeloma are generally immunodeficient, with pronounced depression in primary antibody responses. We have attempted to delineate the reasons for the humoral immunodeficiency by analyzing the specificity repertoire of the surface immunoglobulin (Ig)-positive B cells in patients with multiple myeloma or monoclonal gammopathy of undetermined significance (MGUS), in comparison with normal donors. B lymphocytes from 26 patients with multiple myeloma, 12 patients with MGUS, and 8 normal donors were transformed with Epstein-Barr virus (EBV) and cultured at limiting dilution for clonal analysis. The Ig secreted by each clone was analyzed for class and anti-tetanus toxoid (TT) specificity to determine the frequencies of IgM, IgG, anti-TT IgM, and anti-TT IgG antibody-secreting clones. Our objective was to establish whether the inability to mount humoral responses to common environmental pathogens was due to a lack of specific B cells or to inhibition of B-cell function. Our results indicate that the quantitative B-cell deficiency in patients was due to a nonrandom loss of selected sets of B cells. Although most patients had a reduced aggregate number of B cells, the number of TT-specific B cells was normal. There was, on average, a threefold increase in the proportion of the B-cell specificity repertoire devoted to recognition of TT. Forty-four percent of the patients with MGUS were also affected. In addition, the TT-specific B cells in multiple myeloma patients were severely compromised in their ability to secrete antibody or to differentiate to antibody-secreting cells in vivo. This arrest in differentiation appears to be extrinsic to the B cells, as they were fully able to secrete anti-TT antibody after transformation and culture in vitro. We postulate the existence of an autoimmune inhibitory network mediating the arrest in B-cell differentiation and the humoral immune deficiency.

Impaired chemiluminescence response by neutrophils in patients with multiple myeloma

Neutrophil chemiluminescence (CL) as a measure of oxygen-dependent killing activity was evaluated in 3 groups of patients: (a) 63 patients with multiple myeloma (MM); (b) 31 subjects with monoclonal gammopathy of undetermined significance (MGUS); (c) 32 healthy controls. Neutrophil CL response was shown to be significant reduced both in patients with MM (p less than 0.001) and in subjects with MGUS (p less than 0.001). A significant difference was also observed between the results obtained in MM and those of MGUS (p less than 0.001). Treated MM patients showed a more severe impairment of neutrophil chemiluminescence response than that observed in untreated patients (p less than 0.001). It is suggested that the impairment of neutrophil CL response, possibly related to decreased killing activity, may play a role, along with other known causes, in the increased susceptibility to infection observed in MM patients.

Impaired immunoglobulin synthesis in multiple myeloma: a B-cell dysfunction

Peripheral blood samples collected from normal individuals and patients with benign monoclonal gammopathy and multiple myeloma were separated and assayed for their T- and B-cell subpopulations as well as immunoglobulin (IgG, IgM) synthesis in vitro. To rule out any functional or quantitative alterations related to therapy, only newly diagnosed multiple myeloma patients and subjects with benign monoclonal gammopathy were included in our study. Multiple myeloma patients were further subdivided into two groups. Group A consisted of patients with low and intermediate tumor burdens, while group B included patients with high tumor mass. B- and T-cell subset analysis revealed an abnormal ratio between B/T and OKT4+/OKT8+ lymphocytes compared to healthy controls. These alterations were especially prominent in group B multiple myeloma. Immunoglobulin synthesis was studied in pokeweed-mitogen-stimulated lymphocyte cultures. The results indicate that the failure to synthesize and secrete immunoglobulin resides within the B-cell lineage and is probably due to a functional B-cell defect. T-cell immunoregulatory functions seem to be unaffected in both multiple myleoma and benign monoclonal gammopathy patients.

Abnormal function of B lymphocytes from peripheral blood of multiple myeloma patients. Lack of correlation between the number of cells potentially able to secrete immunoglobulin M and serum immunoglobulin M levels

Multiple myeloma patients are deficient in normal polyclonal serum immunoglobulins. To determine the reasons for this decrease, we quantitated and compared the number of surface IgM+ B lymphocytes, and the number of B cells susceptible to transformation by Epstein-Barr virus (EBV) with the concentration of IgM in serum. Serum IgM levels varied considerably in individual patients, temporally shifting from undetectable to normal amounts and then dropping again to undetectable levels. A transient rise to normal serum IgM concentrations was seen in 42% of patients assessed at two or more time points. Of 44 patients, 52% showed a lack of correlation between the number of surface IgM+ (sIgM+) B cells and serum IgM concentration. One subset of patients (25%) had detectable to normal numbers of sIgM+ B cells in blood but undetectable levels of serum IgM. Transformation of B cells from these patients indicated a block in IgM secretion that was extrinsic to the B cells that were fully able to transcribe, translate, and secrete IgM after EBV transformation. A second subset of patients (27%) had undetectable numbers of sIgM+ B cells but near normal levels of serum IgM, suggesting abundant secretion by few clones of B cells. Of 18 patients with monoclonal gammopathy of undetermined significance (MGUS), 26% showed a lack of correlation between the numbers of sIgM+ B cells and serum IgM concentration. We suggest that in patients with multiple myeloma, and in some with MGUS, there exists a mechanism(s) extrinsic to the B cell that mediates an arrest in terminal B lymphocyte maturation.

Severe deficiency of B lymphocytes in peripheral blood from multiple myeloma patients

A major problem in the assessment of circulating B lymphocytes in multiple myeloma is the extent to which cells with passively absorbed Ig contribute to the assay. We have analyzed peripheral blood B cell numbers in 51 patients in various treatment categories by using an assay that is not subject to artifacts involving cytophilic Ig. We have defined a B lymphocyte by three different criteria (a) expression of a high surface density of Ig (b) expression of a high density of HLA.DR and (c) expression of a marker exclusive to surface Ig+ B cells. By these criteria, normal individuals have an average of 6% B cells. In multiple myeloma patients, B cell levels in purified mononuclear cell preparations are severely reduced. Untreated patients and the majority of patients on intermittent chemotherapy have 20-600-fold fewer B cells than do normal donors (average = 0.3%). This decrease was even greater in whole blood of patients as compared with normal donors (100-1,000-fold fewer B cells). The number of B cells did not correlate with disease status or paraprotein concentration. We found no evidence to support the idea that B lymphocytes in patients include a substantial monoclonal subset.

In vitro immunoglobulin production by peripheral blood mononuclear cells from multiple myeloma patients and patients with benign monoclonal gammopathy. Regulation by cell subsets

Peripheral blood mononuclear cells (PBM) from four patients with IgG myeloma and four patients with benign monoclonal gammopathy (BMG) were stimulated with pokeweed mitogen (PWM), and the in vitro immunoglobulin production over 7 days was measured with an enzyme-linked immunosorbent assay. All myeloma patients were sufficiently treated with cytostatic drugs. Their PBM did not produce monoclonal Ig in vitro, as opposed to PBM from two patients with BMG. Unseparated PBM from myeloma patients produced smaller amounts of polyclonal Ig than unseparated cells from normal donors. However, macrophage-depleted PBM from myeloma patients produced amounts of Ig comparable to those of normal donors when autologous or allogeneic adherent cells were returned in defined numbers. T cells from three of the four myeloma patients could provide help for the Ig production by B cells from healthy donors. These results indicate that functionally normal polyclonal B cells circulate in the blood of myeloma patients. The circulating T-cell population also has no obvious defect. In contrast, blood macrophages seemed to be altered with respect to their regulating function for polyclonal Ig production. The results obtained by using cell populations from patients with BMG did not differ from those of healthy people.

Serum beta-2-microglobulin binding activity in monoclonal gammopathy: correlative study and clinical significance

Serum beta 2m binding activity (S beta 2m-BA) was determined by a polyethylene glycol exclusion test of radiolabeled human beta 2m in 185 serum samples from 62 patients with multiple myeloma (MM). Elevated S beta 2m-BA was found in more than half of the samples from IgG myeloma taken before treatment or during progression of the disease but not during the plateau-phase. Conversely, elevated S beta 2m-BA was found in only one case of IgA myeloma, one case of monoclonal gammopathy of undetermined significance and none of the Bence Jones myelomas. S beta 2m-BA appears to be related to disease progression in IgG myeloma. The activity is supported by minute amounts of serum autoantibodies which are distinct from the monoclonal component. S beta 2m-BA was independent from serum beta 2m levels.

Nonsecretory multiple myeloma

The clinical features and disease course of 29 consecutive multiple myeloma patients without monoclonal globulins are described. This variant accounted for 4.7% of all patients with this disease referred over a 17 year time span. Despite bone marrow plasmacytosis and multiple bone lesions in all, hemoglobin levels were less frequently depressed and immunoglobulin values more frequently preserved in comparison with typical myeloma patients. A low tumor mass was defined in 69%, in comparison with 24% of those with evidence of myeloma protein production. Such earlier disease contributed to the long median survival of 39 months in these patients, a duration about 1 year longer than that of typical patients.

Benign monoclonal gammopathy and peripheral neuropathy

Peripheral neuropathy has been described in malignant plasma cell dyscrasias such as multiple myeloma and Waldenstöm's macroglobulinaemia. Since it is not known whether the neuropathy is related to the plasma cell disorder or is a paramalignant phenomenon, 21 consecutive out-patients with benign monoclonal gammopathy (BMG) were analysed for peripheral neuropathies. Eleven patients had noticed slight motor and/or sensory extremity symptoms. Clinical examination, electromyographic and electroneurographic studies of the upper and lower extremities were performed. In five patients all results indicated a neuropathy, six other patients had clinical signs of neuropathy and four additional patients had positive electromyographic and/or electroneurographic results compatible with neuropathy. There were no significant differences in haematological parameters between the group where all results indicated a neuropathy and the totally negative group or between the two groups with and without clinical neuropathy. Thus, the benign form of plasma cell dyscrasias seems also to be associated with mild clinical or subclinical peripheral neuropathy.

Serum beta-2-microglobulin in multiple myeloma: relation to presenting features and clinical status

Serum beta-2-microglobulin (B2m) levels were measured in 78 patients with multiple myeloma (MM) and were compared with values for normal individuals and patients with benign monoclonal gammopathies (BMG). Serum B2m levels and values corrected for renal function were significantly higher in patients with MM at time of diagnosis than in normal individuals (P less than 0.001) and were highly correlated with the total body burden of myeloma cells as derived from the staging system of Durie and Salmon. However there were no significant differences between values for BMG and low-mass MM. For patients evaluated following induction chemotherapy, there was also a clear correlation between serum B2m levels and the magnitude of tumor regression or progression (P less than 0.05). During the plateau-phase, serum B2m levels remained very stable and highly correlated with the residual tumor mass (P less than 0.001). It was concluded that (1) B2m was not a reliable marker to distinguish between BMG and low-mass MM and (2) B2m was a valuable marker for assessing initial tumor mass of patients with MM and response to chemotherapy (especially the plateau-phase), above all in patients with urine or low-serum monoclonal component levels.