Predicting risk of progression in relapsed multiple myeloma using traditional risk models, focal lesion assessment with PET-CT and minimal residual disease status.

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Therapeutic Advances in the Management of Smoldering Myeloma.

BACKGROUND: The International Myeloma Working Group has defined smoldering multiple myeloma (SMM) as the presence of 10%-60% plasma cells in the bone marrow and M-protein (IgG, IgA) ≥3 g/dL without end-organ damage (an increased calcium level, renal failure, anemia, and destructive bone lesions). AREAS OF UNCERTAINTY: Patients considered to have SMM should not have any myeloma-defining events or amyloidosis. Different risks factors classify SMM into low-, intermediate-, or high-risk categories. The rate of progression from SMM to symptomatic myeloma is ∼10% per year during the first 5 years of diagnosis. SMM requires frequent follow-up ∼every 3 months during the first 5 years as compared to monoclonal gammopathy of undermined significance, which usually requires follow-up every 6-12 months after the first year of diagnosis. DATA SOURCES: A literature search was performed from electronic bibliographic databases: MEDLINE (Ovid SP/PubMed), EMBASE, the Cochrane Library (Cochrane Database of Systematic Reviews), and Cochrane Central Register of Controlled Trials and from annual meeting abstracts from inception to May 2017. THERAPEUTIC ADVANCES: This review presents the literature and available data that support or do not support early treatment of high-risk SMM (HR-SMM) and provides evidence-based recommendations for management of SMM patients. Despite emerging data recommending early treatment of HR-SMM, we predict the SMM category may disappear in the near future and patients will be diagnosed with either multiple myeloma or monoclonal gammopathy of undermined significance. CONCLUSIONS: Success with early therapy trials for HR-SMM is largely due to patients meeting current criteria for multiple myeloma that may have been classified as SMM and, therefore, benefitted from therapy. Based on current practices and the literature, SMM should be managed with close follow-up. Based on available data, we suggest SMM to only be treated in clinical trial settings.

Correction to: Upregulation of FOXM1 leads to diminished drug sensitivity in myeloma.

As a result of an author oversight in the original article [1], the legend of Figure 5A and C is inaccurate and one panel in Figure 5C (FOXM1N H929 cells shown in the top row, left) is wrong.

Upregulation of FOXM1 leads to diminished drug sensitivity in myeloma.

BACKGROUND: Following up on previous work demonstrating the involvement of the transcription factor forkhead box M1 (FOXM1) in the biology and outcome of a high-risk subset of newly diagnosed multiple myeloma (nMM), this study evaluated whether FOXM1 gene expression may be further upregulated upon tumor recurrence in patients with relapsed multiple myeloma (rMM). Also assessed was the hypothesis that increased levels of FOXM1 diminish the sensitivity of myeloma cells to commonly used myeloma drugs, such as the proteasome inhibitor bortezomib (Bz) and the DNA intercalator doxorubicin (Dox). METHODS: FOXM1 message was evaluated in 88 paired myeloma samples from patients with nMM and rMM, using gene expression microarrays as measurement tool. Sources of differential gene expression were identified and outlier analyses were performed using statistical methods. Two independent human myeloma cell lines (HMCLs) containing normal levels of FOXM1 (FOXM1N) or elevated levels of lentivirus-encoded FOXM1 (FOXM1Hi) were employed to determine FOXM1-dependent changes in cell proliferation, survival, efflux-pump activity, and drug sensitivity. Levels of retinoblastoma (Rb) protein were determined with the assistance of Western blotting. RESULTS: Upregulation of FOXM1 occurred in 61 of 88 (69%) patients with rMM, including 4 patients that exhibited > 20-fold elevated expression peaks. Increased FOXM1 levels in FOXM1Hi myeloma cells caused partial resistance to Bz (1.9-5.6 fold) and Dox (1.5-2.9 fold) in vitro, using FOXM1N myeloma as control. Reduced sensitivity of FOXM1Hi cells to Bz was confirmed in vivo using myeloma-in-mouse xenografts. FOXM1-dependent regulation of total and phosphorylated Rb agreed with a working model of myeloma suggesting that FOXM1 governs both chromosomal instability (CIN) and E2F-dependent proliferation, using a mechanism that involves interaction with NIMA related kinase 2 (NEK2) and cyclin dependent kinase 6 (CDK6), respectively. CONCLUSIONS: These findings enhanced our understanding of the emerging FOXM1 genetic network in myeloma and provided preclinical support for the therapeutic targeting of the FOXM1-NEK2 and CDK4/6-Rb-E2F pathways using small-drug CDK and NEK2 inhibitors. Clinical research is warranted to assess whether this approach may overcome drug resistance in FOXM1Hi myeloma and, thereby, improve the outcome of patients in which the transcription factor is expressed at high levels.

Pooled study of occupational exposure to aromatic hydrocarbon solvents and risk of multiple myeloma.

OBJECTIVES: To investigate the association between occupational exposure to aromatic hydrocarbon solvents and risk of multiple myeloma (MM) in a large, consortium-based study. METHODS: We pooled data on 2854 cases and 10 743 controls from nine studies participating in the InterLymph consortium. Occupational exposures to benzene, toluene and xylene were assigned by a job-exposure matrix, coupled with 'correction' of exposure probability by self-reported or expert-assessed exposure from the individual studies. Cumulative intensity was calculated as the job-specific exposure intensity multiplied by job duration, summed across jobs. Associations were estimated using logistic regression, with inclusion of covariates for study matching factors and other potential confounders. We repeated our main analysis using random-effects meta-analysis to evaluate heterogeneity of effect. RESULTS: Benzene, toluene and xylene were each associated with MM. For the three solvents, the highest quartile of high-probability cumulative intensity exposure (vs unexposed) was associated with 42% to 63% increased risks of MM. Associations with toluene and xylene exposures were fairly consistent and robust to sensitivity analyses. The estimated effect for benzene was moderately heterogeneous between the studies. Each solvent's association with MM was stronger for exposure occurring within 20 years of diagnosis than with exposure lagged by more than 20 years. CONCLUSIONS: Our study adds important evidence for a role of aromatic hydrocarbon solvents in causation of MM. The difficulty in disentangling individual compounds in this group and a lack of data on potential carcinogenicity of toluene and xylene, in widespread current use, underscore a need for further epidemiological evaluation.

Potential pitfalls of serum free light chain analysis to assess treatment response for multiple myeloma.

Response to treatment in patients with a plasma cell disorder is typically measured by evaluating the bone marrow and myeloma markers, including monoclonal protein spike and immunofixation (IFE) in blood and urine, and serum free light chains (sFLCs). Stringent complete response criteria for Multiple Myeloma (MM) patients require a normal FLC ratio and absence of clonal cells in bone marrow by immunohistochemistry or immunofluorescence. We performed a retrospective chart review to further evaluate these criteria. A total of 142 patient charts were analysed. Of these, 17 patients were found to have an abnormal sFLC ratio, but no other evidence of disease, including normal flow cytometry and normal fluorescence in situ hybridization (FISH) analysis on highly selected plasma cells. In all patients, the abnormal sFLC ratio was caused by abnormalities in the serum kappa light chains. These results suggest that current definitions may need to be revised to take aberrancies related to abnormal immune recovery into account.

Multiple myeloma and family history of lymphohaematopoietic cancers: Results from the International Multiple Myeloma Consortium.

Family clusters of multiple myeloma (MM) suggest disease heritability. Nevertheless, patterns of inheritance and the importance of genetic versus environmental risk factors in MM aetiology remain unclear. We pooled data from eleven case-control studies from the International Multiple Myeloma Consortium to characterize the association of MM risk with having a first-degree relative with a history of a lympho-haematapoietic cancer. Unconditional logistic regression models, adjusted for study, sex, age and education level, were used to estimate associations between MM risk and having a first-degree relative with a history of non-Hodgkin lymphoma, Hodgkin lymphoma, leukaemia or MM. Sex, African American race/ethnicity and age were explored as effect modifiers. A total of 2843 cases and 11 470 controls were included. MM risk was elevated in association with having a first-degree relative with any lympho-haematapoietic cancer (Odds Ratio (OR) = 1·29, 95% Confidence Interval (CI): 1·08-1·55). The association was particularly strong for having a first-degree relative with MM (OR = 1·90, 95% CI: 1·26-2·87), especially among men (OR = 4·13, 95% CI: 2·17-7·85) and African Americans (OR = 5·52, 95% CI: 1·87-16·27).These results support the hypothesis that genetic inheritance plays a role in MM aetiology. Future studies are warranted to characterize interactions of genetic markers with environmental exposures.

RARα2 expression confers myeloma stem cell features.

We previously demonstrated that RARα2 expression is increased in CD138 selected plasma cells of relapsed multiple myelomas (MMs), and increased expression was linked to poor prognosis in newly diagnosed MM patients. In the present study, we demonstrate that increased RARα2 confers myeloma stem cell features. Higher expression of RARα2 was identified in the multiple myeloma stem cell (MMSC) fraction. Overexpression of RARα2 in bulk MM cell lines resulted in: 1) increased drug resistance; 2) increased clonogenic potential; 3) activation of both Wnt and Hedgehog (Hh) pathways; 4) increased side population and aldehyde dehydrogenase levels; and 5) increased expression of embryonic stem cell genes. The opposite effects were seen with RARα2 knockdown. We demonstrate that RARα2 induces drug resistance by activating the drug efflux pump gene ABCC3 and anti-apoptotic Bcl-2 family members. Inhibition of Wnt signaling or ABCC3 function could overcome drug resistance in RARα2 overexpressing MM cells. We also showed that in the 5TGM1 mouse model, targeting of the Wnt and Hh pathways using CAY10404, cyclopamine, or itraconazole significantly reduced the myeloma tumor burden and increased survival. Targeting RARα2 or its downstream signaling pathways provides a potential strategy to eliminate MMSC.

Evaluation of the spectra Optia® mononuclear cell collection procedure in multiple myeloma patients.

BACKGROUND: Peripheral blood stem cell (PBSC) rescue following myeloablative therapy is a mainstay of cancer therapy. To evaluate the ability of the Spectra Optia Apheresis System (SO), a newly developed apheresis device, the device was studied in multiple myeloma patients undergoing a first autologous PBSC transplant. AIM: To demonstrate that neutrophil recovery was not inferior to historical controls when SO harvested PBSCs were reinfused following myeloablative therapy. METHODS: Multiple myeloma patients were mobilized according to the standard practice at four clinical sites. Following mobilization, MNC collections were performed on the SO. The collected cells were cryopreserved and reinfused following myeloablative chemotherapy. Neutrophil recovery defined by an absolute neutrophil count exceeding 500/µL (ANC500) was compared to historical data for patients transplanted following apheresis using the COBE Spectra (CS) device. RESULTS: The median day to neutrophil recovery was 12 days (range 10-14 days), with no significant difference in engraftment comparing patients transplanted with stem cells collected using the SO versus historical cohort of patients collected with the CS. CD34+ cell and MNC collection efficiency (CE) were 69.3% and 65.0% for the SO and CS, respectively. Platelet CE, product hematocrit and product granulocytes (as % of WBCs) using the SO were 21%, 2.3% and 28%, respectively. There were no device-related severe adverse events. CONCLUSIONS: The study's results confirm that the Spectra Optia Apheresis System's MNC Collection Protocol is safe and effective for its intended use and that engraftment kinetics of cells collected by SO is not inferior to the CS System.

Safety and efficacy of targeted-dose busulfan and bortezomib as a conditioning regimen for patients with relapsed multiple myeloma undergoing a second autologous blood progenitor cell transplantation.

Patients with multiple myeloma (MM) who relapse after autologous transplantation have limited therapeutic options. We conducted a prospective, multicenter, phase IIa study to investigate the safety and efficacy of i.v. busulfan (Bu) in combination with bortezomib as a conditioning regimen for a second autotransplantation. Because a safe Bu exposure was unknown in patients receiving this combination, Bu was initially targeted to a total area under the concentration-time curve (AUC) of 20,000 µM × minute. As no concentration-limiting toxicity was observed in 6 patients, this Bu exposure was utilized in the following treatment cohort (n = 24). Individualized Bu dose, based on test dose .8 mg/kg pharmacokinetics (PK), was administered daily for 4 consecutive days starting 5 days before transplantation, followed by a single dose of bortezomib (1.3 mg/m(2)) 1 day before transplantation. The total mean dose of i.v. Bu (including the test dose and 4-day administration) was 14.2 mg/kg (standard deviation = 2.48; range, 8.7 to 19.2). Confirmatory PK demonstrated that only 2 of 30 patients who underwent transplantation were dosed outside the Bu AUC target and dose adjustments were made for the last 2 doses of i.v. Bu. The median age was 59 years (range, 48 to 73). Median time from first to second transplantation was 28.0 months (range, 12 to 119). Of 26 evaluable patients, 10 patients attained a partial response (PR) or better at 3 months after transplantation, with 2 patients attaining a complete response. At 6 months after transplantation, 5 of 12 evaluable patients had maintained or improved their disease status. Median progression-free survival was 191 days, whereas median overall survival was not reached during the study period. The most common grade 3 and 4 toxicities were febrile neutropenia (50.0%) and stomatitis (43.3%). One transplantation-related death was observed. A combination of dose-targeted i.v. Bu and bortezomib induced PR or better in one third of patients with MM who underwent a second autotransplantation, with acceptable toxicity.

Three years of maintenance with VRD in multiple myeloma: results of total therapy IIIB with a 15-year follow-up.

ABSTRACT: The total therapy (TT) IIIB phase 2 study incorporated bortezomib into tandem melphalan-based hematopoietic stem cell transplantation with dexamethasone, thalidomide, cisplatin, doxorubicin, cyclophosphamide, and etoposide for induction/consolidation and bortezomib, lenalidomide, and dexamethasone (VRD) for maintenance in patients with newly diagnosed multiple myeloma (MM). This updated analysis presents a 15.4-year median follow-up. Of 177 patients, 21% patients had gene expression profile (GEP)-defined high-risk MM. 15-year progression free survival (PFS) was 27.9%. Median PFS was better in GEP-defined low-risk patients at 7.8 years and in International Staging System stage 1 patients at 8.7 years. Overall, median OS was 9.1 years, and 15-year overall survival (OS) was 35.9%. GEP-defined low-risk patients' median OS was 11.2 years, and that of GEP-defined high-risk patients was 2.8 years. There was no difference in OS between TT IIIB and TT IIIA. This study includes the longest follow-up of patients treated with maintenance VRD reported to date. In patients with GEP-defined low-risk, nearly half and one-third of patients without ongoing treatment showed no signs of progression at 10 and 15 years, respectively. One-third of patients survived more than 15 years, but 3 years of VRD maintenance did not improve outcomes for patients with GEP-defined high-risk MM. The study was registered on www.clinicaltrials.gov as #NCT00572169.

BCMA- and CST6-specific CAR T cells lyse multiple myeloma cells and suppress murine osteolytic lesions.

We have previously demonstrated that cystatin E/M (CST6), which is elevated in a subset of patients with multiple myeloma (MM) lacking osteolytic lesions (OLs), suppresses MM bone disease by blocking osteoclast differentiation and function. CST6 is a secreted type 2 cystatin, a cysteine protease inhibitor that regulates lysosomal cysteine proteases and the asparaginyl endopeptidase legumain. Here, we developed B cell maturation antigen (BCMA) CST6 chimeric antigen receptor T cells (CAR-T cells), which lysed MM cells and released CST6 proteins. Our in vitro studies show that these CAR-T cells suppressed the differentiation and formation of tartrate-resistant acid phosphatase-positive (TRAP+) osteoclasts. Using xenografted MM mice, bioluminescence images showed that both BCMA-CAR-T and BCMA-CST6-CAR-T cells inhibited MM growth to a similar extent. Reconstructed micro-computed tomography images revealed that BCMA-CST6-CAR-T cells, but not BCMA-CAR-T cells, prevented MM-induced bone damage and decreased osteoclast numbers. Our results provide a CAR-T strategy that targets tumor cells directly and delivers an inhibitor of bone resorption.

Cystatin M/E ameliorates bone resorption through increasing osteoclastic cell estrogen influx.

In multiple myeloma (MM), increased osteoclast differentiation leads to the formation of osteolytic lesions in most MM patients. Bisphosphonates, such as zoledronic acid (ZA), are used to ameliorate bone resorption, but due to risk of serious side effects as well as the lack of repair of existing lesions, novel anti-bone resorption agents are required. Previously, the absence of osteolytic lesions in MM was strongly associated with elevated levels of cystatin M/E (CST6), a cysteine protease inhibitor, secreted by MM cells. In this study, both MM- and ovariectomy (OVX)-induced osteoporotic mouse models were used to compare the effects of recombinant mouse CST6 (rmCst6) and ZA on preventing bone loss. µCT showed that rmCst6 and ZA had similar effects on improving percent bone volume, and inhibited differentiation of non-adherent bone marrow cells into mature osteoclasts. Single-cell RNA sequencing showed that rmCst6 and not ZA treatment reduced bone marrow macrophage percentage in the MM mouse model compared to controls. Protein and mRNA arrays showed that both rmCst6 and ZA significantly inhibit OVX-induced expression of inflammatory cytokines. For OVX mice, ERα protein expression in bone was brought to sham surgery level by only rmCst6 treatments. rmCst6 significantly increased mRNA and protein levels of ERα and significantly increased total intracellular estrogen concentrations for ex vivo osteoclast precursor cell cultures. Based on these results, we conclude that CST6 improves MM or OVX bone loss models by increasing the expression of estrogen receptors as well as the intracellular estrogen concentration in osteoclast precursors, inhibiting their maturation.

A Risk Stratification System in Myeloma Patients with Autologous Stem Cell Transplantation.

Autologous stem cell transplantation (ASCT) has been a mainstay in myeloma treatment for over three decades, but patient prognosis post-ASCT varies significantly. In a retrospective study of 5259 patients with multiple myeloma (MM) at the University of Arkansas for Medical Sciences undergoing ASCT with a median 57-month follow-up, we divided the dataset into training (70%) and validation (30%) subsets. Employing univariable and multivariable Cox analyses, we systematically assessed 29 clinical variables, identifying crucial adverse prognostic factors, such as extended duration between MM diagnosis and ASCT, elevated serum ferritin, and reduced transferrin levels. These factors could enhance existing prognostic models. Additionally, we pinpointed significant poor prognosis markers like high serum calcium and low platelet counts, though they are applicable to a smaller patient population. Utilizing seven easily accessible high-risk variables, we devised a four-stage system (ATM4S) with primary stage borders determined through K-adaptive partitioning. This staging system underwent validation in both the training dataset and an independent cohort of 514 ASCT-treated MM patients from the University of Iowa. We also explored cytogenetic risk factors within this staging system, emphasizing its potential clinical utility for refining prognostic assessments and guiding personalized treatment approaches.

Bispecific BCMA/CD24 CAR-T cells control multiple myeloma growth.

Anti-multiple myeloma B cell maturation antigen (BCMA)-specific chimeric antigen receptor (CAR) T-cell therapies represent a promising treatment strategy with high response rates in myeloma. However, durable cures following anti-BCMA CAR-T cell treatment of myeloma are rare. One potential reason is that a small subset of minimal residual myeloma cells seeds relapse. Residual myeloma cells following BCMA-CAR-T-mediated treatment show less-differentiated features and express stem-like genes, including CD24. CD24-positive myeloma cells represent a large fraction of residual myeloma cells after BCMA-CAR-T therapy. In this work, we develop CD24-CAR-T cells and test their ability to eliminate myeloma cells. We find that CD24-CAR-T cells block the CD24-Siglec-10 pathway, thereby enhancing macrophage phagocytic clearance of myeloma cells. Additionally, CD24-CAR-T cells polarize macrophages to a M1-like phenotype. A dual-targeted BCMA-CD24-CAR-T exhibits improved efficacy compared to monospecific BCMA-CAR-T-cell therapy. This work presents an immunotherapeutic approach that targets myeloma cells and promotes tumor cell clearance by macrophages.

Application of R2-ISS risk stratification to patients with multiple myeloma treated with autologous stem cell transplants at UAMS.

The Second Revision of the International Staging System (R2-ISS) was published in 2022 and has been validated in several cohorts of patients with multiple myeloma (MM). In this study, we investigated a total of 860 patients with MM who received an upfront autologous stem cell transplantation between 2001 and 2021. The median age of the patients was 60 years, with a median overall survival (OS) of 123 months and median progression-free survival (PFS) of 70 months. We collected the variables included in the ISS, R-ISS, and R2-ISS systems as well as additional standard variables. Our analyses demonstrated that all 3 ISS series systems (ISS, R-ISS, and R2-ISS) exhibited robust discrimination in terms of both OS and PFS among our study cohort. The ISS system effectively stratified patients into 3 risk groups, whereas the R-ISS system accurately identified patients at extremely high or low risk. The R2-ISS system further refined risk stratification by dividing patients into 4 more balanced risk groups. Furthermore, we specifically focused on identifying variables that distinguished patients with OS < 3 years and OS > 10 years within the low-risk R2-ISS stages (I and II) and high-risk R2-ISS stages (III and IV). Our findings revealed that age, hemoglobin, and 1p deletion significantly influenced the classification of patients in the low-risk R2-ISS stage. Additionally, serum light chain, platelet count, age, and the presence of the t(14;16) translocation were found to affect high-risk classification.

A gene signature can predict risk of MGUS progressing to multiple myeloma.

Multiple myeloma is preceded by monoclonal gammopathy of undetermined significance (MGUS). Serum markers are currently used to stratify MGUS patients into clinical risk groups. A molecular signature predicting MGUS progression has not been produced. We have explored the use of gene expression profiling to risk-stratify MGUS and developed an optimized signature based on large samples with long-term follow-up. Microarrays of plasma cell mRNA from 334 MGUS with stable disease and 40 MGUS that progressed to MM within 10 years, was used to define a molecular signature of MGUS risk. After a three-fold cross-validation analysis, the top thirty-six genes that appeared in each validation and maximized the concordance between risk score and MGUS progression were included in the gene signature (GS36). The GS36 accurately predicted MGUS progression (C-statistic is 0.928). An optimal cut-point for risk of progression by the GS36 score was found to be 0.7, which identified a subset of 61 patients with a 10-year progression probability of 54.1%. The remainder of the 313 patients had a probability of progression of only 2.2%. The sensitivity and specificity were 82.5% and 91.6%. Furthermore, combination of GS36, free light chain ratio and immunoparesis identified a subset of MGUS patients with 82.4% risk of progression to MM within 10 years. A gene expression signature combined with serum markers created a highly robust model for predicting risk of MGUS progression. These findings strongly support the inclusion of genomic analysis in the management of MGUS to identify patients who may benefit from more frequent monitoring.