Demonstration of changes in plasma cell subsets in multiple myeloma

Clinical characteristics and prognostic significance of immunoglobulin isotype switch in patients with multiple myeloma

Immunoglobulin (Ig) isotype switching in multiple myeloma (MM) is a rare form of clonal evolution. The aim of this study was to investigate the clinical features and prognostic significance of Ig isotype switching by observing Ig transformation in patients with relapse. A retrospective analysis was performed on 506 patients with newly diagnosed MM who were treated at our hospital from February 2005 to February 2020. The patients who experienced relapse were divided into the following four groups according to Ig phenotype: original paraprotein, complete isotype switching, light chain escape (LCE),and non-secretory clinical relapse. For comparative purposes with the original paraprotein group, the last three groups were pooled as the transformation group. Among the 506 included patients, 376 (74.3%) relapsed. Among them, 13/376 (3.5%) patients exhibited Ig isotype switching, including 3 with complete isotype switching, 3 with LCE, and 7 with non-secretory clinical relapse. Eleven remained sensitive to therapy, exhibiting at least a partial response. Seven patients survived for at least 20 months after relapse. The median overall survival time of the LCE, clinical relapse, and complete isotype switching groups were 6, 20, and 76 months, respectively, after recurrence. The clinical manifestations and Ig phenotypes of MM recurrence were different from those at the initial diagnosis in the 13 patients exhibiting Ig isotype switching. These differences vividly conveyed the heterogeneity of the clonal populations and provides direct clinical evidence for MM clonal evolution.

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.

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.

Multi-omics tumor profiling technologies to develop precision medicine in multiple myeloma

Multiple myeloma (MM), the second most common hematologic cancer, is caused by accumulation of aberrant plasma cells in the bone marrow. Its molecular causes are not fully understood and its great heterogeneity among patients complicates therapeutic decision-making. In the past decades, development of new therapies and drugs have significantly improved survival of MM patients. However, resistance to drugs and relapse remain the most common causes of mortality and are the major challenges to overcome. The advent of high throughput omics technologies capable of analyzing big amount of clinical and biological data has changed the way to diagnose and treat MM. Integration of omics data (gene mutations, gene expression, epigenetic information, and protein and metabolite levels) with clinical histories of thousands of patients allows to build scores to stratify the risk at diagnosis and predict the response to treatment, helping clinicians to make better educated decisions for each particular case. There is no doubt that the future of MM treatment relies on personalized therapies based on predictive models built from omics studies. This review summarizes the current treatments and the use of omics technologies in MM, and their importance in the implementation of personalized medicine.

Multi-omics tumor profiling technologies to develop precision medicine in multiple myeloma

Multiple myeloma (MM), the second most common hematologic cancer, is caused by accumulation of aberrant plasma cells in the bone marrow. Its molecular causes are not fully understood and its great heterogeneity among patients complicates therapeutic decision-making. In the past decades, development of new therapies and drugs have significantly improved survival of MM patients. However, resistance to drugs and relapse remain the most common causes of mortality and are the major challenges to overcome. The advent of high throughput omics technologies capable of analyzing big amount of clinical and biological data has changed the way to diagnose and treat MM. Integration of omics data (gene mutations, gene expression, epigenetic information, and protein and metabolite levels) with clinical histories of thousands of patients allows to build scores to stratify the risk at diagnosis and predict the response to treatment, helping clinicians to make better educated decisions for each particular case. There is no doubt that the future of MM treatment relies on personalized therapies based on predictive models built from omics studies. This review summarizes the current treatments and the use of omics technologies in MM, and their importance in the implementation of personalized medicine.

Serum Free Light Chain (FLC) Analysis: A Guiding Light in Monoclonal Gammopathy Management

BACKGROUND

Monoclonal free light chains (FLCs) were first reported by Dr. Henry Bence Jones over 150 years ago in the urine of patients with multiple myeloma. Now established as important tumor markers, they aid not only in the diagnosis of monoclonal gammopathies but also in their clinical management by indicating the response to treatment and persistence of residual disease.

CONTENT

A particular focus over the past 15 years has been on the replacement of urine with serum analysis for monoclonal FLC measurement. Because of the limited sensitivity and practical constraints of urine assessment, a combination of serum electrophoresis and serum FLC analysis has been adopted by many laboratories as a first-line screen for patients with a suspected monoclonal gammopathy. Early myeloma diagnosis may translate into improved clinical outcomes, and a new study, iStopMM, is underway to ascertain the benefit of population-wide screening protocols for early detection of the disease in its asymptomatic phase. Laboratory algorithms that include measurement of both monoclonal intact immunoglobulins and FLCs are important for assessing possible changes in myelomic clones in response to treatment, and recent data from Intergroupe Francophone du Myelome trials validate serum FLC as a clinically relevant disease biomarker. Whether sensitive serum techniques such as FLC analysis can be used to guide the use of more invasive procedures for detection of minimal residual disease is the subject of emerging studies.

SUMMARY

Here we review the current and evolving utility of serum FLC measurements for the management of patients with monoclonal gammopathies.

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

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

Light Chain Escape in 3 Cases: Evidence of Intraclonal Heterogeneity in Multiple Myeloma from a Single Institution in Poland

We report three cases of light chain escape (LCE) at a single institution in Poland, including an interesting case of biclonal monoclonal gammopathy of undetermined significance (MGUS) that satisfied the criteria for progression to light chain multiple myeloma (LCMM) with a rapid rise in serum free light chain (FLC) levels, following steroidal treatment for simultaneous temporal artery inflammation and polymyalgia rheumatica (PMR). In the three cases discussed, progression of the disease by light chain escape was associated with rapid and severe renal impairment, highlighting the necessity for prompt detection of such free light chain-only producing clones in order to prevent the possible development of irreversible end-organ damage. Interestingly, monitoring of these three patients by serum free light chain assay (sFLC) and retrospective heavy/light chain analysis (HLC) detected this clonal evolution prior to clinical relapse and suggests that these assays represent important additional tools for more accurate monitoring of multiple myeloma patients.

Immunoglobulin heavy/light chain analysis enhances the detection of residual disease and monitoring of multiple myeloma patients

AIM

To evaluate the clinical utility of incorporating a novel heavy/light chain immunoassay (HLC) into the existing methods for the assessment of multiple myeloma (MM) patients.

METHODS

Convenience sera samples from 90 previously treated IgG and IgA MM patients in different disease stages were analyzed. The study was conducted in Clinical Hospital Center Zagreb between 2011 and 2013. The collected sera were analyzed by standard laboratory techniques (serum protein electrophoresis, quantification of total immunoglobulins, serum immunofixation, serum free light chain [FLC] assay) and HLC assay.

RESULTS

HLC ratios outside the normal range were found in 58 of 90 patients, including 28 out of 61 patients with total immunoglobulin measurements within the normal range and 5 out of 23 patients in complete response. Both elevated HLC isotype level and abnormal HLC ratio correlated with the parameters of tumor burden, including percentage of plasma cells in the bone marrow (P<0.001 and P=0.002, respectively) and an abnormal serum FLC ratio (for both P<0.001). In addition, abnormal HLC isotype level correlated with serum beta-2-microglobulin level (P=0.038). In terms of prognosis, abnormal HLC isotype level and abnormal HLC ratio were significantly associated with shorter overall survival (P<0.001 and P=0.002, respectively). Interestingly, suppression of the uninvolved (polyclonal) isotype pair, but not other non-myeloma immunoglobulin isotypes, was also associated with a shorter overall survival (P=0.021). In a multivariate analysis, an abnormal HLC ratio and β2-microglobulin level >3.5mg/L were independent risk factors for survival.

CONCLUSION

The new HLC assay has greater sensitivity in detecting monoclonal protein, correlates with tumor burden markers, and affects patients' outcome.

Serum free immunoglobulin light chain evaluation as a marker of impact from intraclonal heterogeneity on myeloma outcome

The type of antibody secreted at relapse can serve as a marker of clonal heterogeneity. It is important to monitor for serum FLC in the suspicion of clinical relapse to ensure that FLC relapse is not missed.

Helical tomotherapy and systemic targeted therapies in solitary plasmacytoma: Pilot study

AIM: To assess the feasibility of the combination of helical tomotherapy^® (HT) and a concurrent systemic targeted therapy in patients with solitary plasmacytoma (SP) with the aim to decrease toxicity while improving therapeutic efficacy.

METHODS: Six patients with biologically, histologically, and radiologically confirmed SP were treated using HT and a systemic targeted treatment concomitantly. Total dose was 40 Gy/20 fractions. Four patients received 4 cycles of concurrent lenalidomide-dexamethasone combination and two patients were treated with concomitant bortezomib-dexamethasone. All toxicities were described using the Common Terminology Criteria for Adverse Effects v3.0.

RESULTS: Five patients had a bone tumor and one patient had an isolated pancreatic mass. Five patients presented with pain, one had neurologic symptoms related to medullary compression, which was treated by an emergency surgery. Median age was 59.5 years (range, 50-74 years). All patients had initial positron emission tomography-computed tomographys, three patients had total body bone magnetic resonance imaging examination, and three patients had computed tomodensitometry scans. The toxicity profile was excellent with no higher than grade 1 toxicity. Four of the six patients experienced a partial radiological response, four had complete response on positions emission tomography and 5/6 patients experienced a complete relief of their symptoms 4 mo after treatment. At a median follow-up of 18 mo, 5/6 patients were controlled clinically, radiologically, and biologically.

CONCLUSION: Using HT, we could deliver a highly conformal irradiation concurrently with a molecularly targeted therapy. This association yielded in a high response rate and a low toxicity. A prospective study with longer follow-up will help determining the true benefit of such strategy.

Ratio of involved/uninvolved immunoglobulin quantification by Hevylite™ assay: clinical and prognostic impact in multiple myeloma

Background

HevyLite™ is a new, recently developed method that facilitates separate quantification of the kappa- and lambda-bounded amounts of a given immunoglobulin (Ig). Using this method, we measured intact immunoglobulin (heavy/light chain; HLC) IgG-kappa, IgG-lambda, IgA-kappa, IgA-lambda individually, as well as their deriving ratios (HLCR) in a series of IgG or IgA multiple myeloma (MM) patients, to investigate and assess the contribution of these tests to disease evaluation.

Patients and methods

HevyLite™ assays were used in sera from 130 healthy individuals (HI) and 103 MM patients, at time of diagnosis. In patients, the level of paraprotein was IgG in 78 (52 IgG-kappa, 26 IgG-lambda) and IgΑ in 25 (13 IgΑ-kappa, 12 IgΑ-lambda). Durie-Salmon and International Staging System stages were evenly distributed. Symptomatic patients (n = 77) received treatment while asymptomatic ones (n = 26) were followed. Patients' median follow-up was at 32.6 months. HLCR was calculated with the involved Ig (either G or A) as numerator.

Results

In HI, median IgG-kappa was 6.85, IgG-lambda 3.81, IgA-kappa 1.19 and IgA-lambda 0.98 g/L. The corresponding median involving HLC values in MM patients were 25.8, 23.45, 28.9 and 36.4 g/L. HLC-IgG related to anemia, high serum free light chain ratio and extensive bone marrow infiltration, while high HLCR correlated with the same plus increased β2-microglobulin. In addition, increased HLCR and the presence of immunoparesis correlated with time to treatment. Patients with high HLCR had a significantly shorter survival (p = 0.022); HLCR retained its prognostic value in multivariate analysis.

Conclusions

HLC and HLCR quantify the precise amount of the involved immunoglobulin more accurately than other methods; moreover, they carry prognostic information regarding survival in MM patients.

The role of helical tomotherapy in the treatment of bone plasmacytoma

We evaluated the early clinical outcome of patients with solitary bone plasmacytoma (SP) or a solitary lesion of multiple myeloma (MM) treated with helical tomotherapy (HT) compared with 3D conformal radiotherapy (3D-CRT), in terms of target coverage and exposure of critical organs. Ten patients with SP and 3 patients with a solitary lesion of MM underwent radiation therapy (RT) delivered by HT, to a dose of 40 Gy in 20 fractions. Treatment planning was then performed with 3D-CRT and the dosimetric parameters of both techniques were compared. Patients were also assessed for response to treatment and acute toxicities. With a median follow-up of 13 months, 78% of patients with pain before RT had resolution of their symptoms. Coverage of target lesion was adequate with both techniques in 12 of 13 patients. Target coverage was significantly lower for HT (V(95%) = 98.55% vs. 97.15%; p = 0.04, for 3D-CRT and HT, respectively). Target overdoses were also lower with HT (V(105%) = 2.01% vs. 0.19%; p= 0.16), although nonsignificant. Finally, there were no significant differences in organs-at-risk irradiation between both techniques. The early treatment tolerance was excellent, with no toxicity higher than grade I. RT of SP and MM with a solitary lesion can be safely delivered with HT, with no major acute side effects and good symptomatic control. Finally, HT provides a dosimetry similar to that of 3D-CRT in terms of organs-at-risk sparing and target volume coverage.

Place of modern imaging modalities for solitary plasmacytoma: toward improved primary staging and treatment monitoring

Radiation therapy (RT) is the mainstay of treatment of solitary plasmacytoma. In most cases, doses ranging from 40 to 50 Gy yield in a local control more than 80%. However, the prognosis of patients with SP is marked by a high rate of transformation to multiple myeloma (MM), and there is no demonstrated benefit of adjuvant chemotherapy for decreasing this probability. However, clinical benefits could be reached from improving screening for other primary sites of plasmacytoma and earlier discovering signs suggestive of MM. Since such strategy could provide significant information regarding both prognosis and therapy, it has become first importance to improve initial staging of tumor widespread. Although conventional skeletal X-ray survey remains standard, usual sensitivity of radiographies does not permit diagnosing early myeloma lesions and a significant number of patients with supposed SP might be understaged and do not receive the appropriate treatment. The development of more sensitive and specific imaging modalities will make it feasible to earlier detect subclinical lesions, thus leading lead to new approaches in the treatment strategies. Here, we discuss the benefits and limitations of magnetic resonance imaging and positron emission tomography for primary staging of patients with solitary plasmacytoma. Both imaging modalities could also improve target volume delineation and assessment of tumor response after RT.

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

BACKGROUND

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

METHODS

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

FINDINGS

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

INTERPRETATION

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

FUNDING

US National Cancer Institute.

Solitary plasmocytoma: improvement in critical organs sparing by means of helical tomotherapy

PURPOSE

Helical tomotherapy (HT) was assessed in two patients with paramedullar solitary bone plasmocytoma. We compared doses delivered to critical organs, according HT plan or tridimensional conformal plan.

METHODS AND MATERIALS

One male (patient no. 1), 67 yr-old and one female (patient no. 2), 37-yr-old, with histologically, biologically and radiological confirmed paramedullar solitary plasmocytoma have been treated in our department between November 2007 and February 2008 using HT. The prescription dose was 40 Gy in 20 fractions. This HT treatment planning was compared with a routine dosimetric work that was executed for a standard conformal radiotherapy treatment planning.

RESULTS

Treatment tolerance was excellent, without any side effects. Both patients achieved 9-month complete remission. HT resulted in substantial critical organs sparing. For patient no. 1, dose delivered to 20% of the total intestine volume was reduced from 28 Gy for conformal radiotherapy to 13 Gy for HT. Radiation dose delivered to 20% of the left kidney was reduced from 25 Gy to 7 Gy. For patient no. 2, volume of left lung that received at least 20 Gy was 12% for conformal radiotherapy vs. 6% for HT.

CONCLUSIONS

For paramedullar solitary plasmocytoma, HT has the potential to significantly improve the quality of the dose distribution both in terms of better dose homogeneity within the planning target volume and more efficient sparing of critical organs.