CXCR4 has a dual role in improving the efficacy of BCMA-redirected CAR-NK cells in multiple myeloma.

Multiple myeloma (MM) is a plasma cell disease with a preferential bone marrow (BM) tropism. Enforced expression of tissue-specific chemokine receptors has been shown to successfully guide adoptively-transferred CAR NK cells towards the malignant milieu in solid cancers, but also to BM-resident AML and MM. For redirection towards BM-associated chemokine CXCL12, we armored BCMA CAR-NK-92 as well as primary NK cells with ectopic expression of either wildtype CXCR4 or a gain-of-function mutant CXCR4R334X. Our data showed that BCMA CAR-NK-92 and -primary NK cells equipped with CXCR4 gained an improved ability to migrate towards CXCL12 in vitro. Beyond its classical role coordinating chemotaxis, CXCR4 has been shown to participate in T cell co-stimulation, which prompted us to examine the functionality of CXCR4-cotransduced BCMA-CAR NK cells. Ectopic CXCR4 expression enhanced the cytotoxic capacity of BCMA CAR-NK cells, as evidenced by the ability to eliminate BCMA-expressing target cell lines and primary MM cells in vitro and through accelerated cytolytic granule release. We show that CXCR4 co-modification prolonged BCMA CAR surface deposition, augmented ZAP-70 recruitment following CAR-engagement, and accelerated distal signal transduction kinetics. BCMA CAR sensitivity towards antigen was enhanced by virtue of an enhanced ZAP-70 recruitment to the immunological synapse, revealing an increased propensity of CARs to become triggered upon CXCR4 overexpression. Unexpectedly, co-stimulation via CXCR4 occurred in the absence of CXCL12 ligand-stimulation. Collectively, our findings imply that co-modification of CAR-NK cells with tissue-relevant chemokine receptors affect adoptive NK cell therapy beyond improved trafficking and retention within tumor sites.

[Novel therapies for multiple myeloma].

B-cell maturation antigen (BCMA)-targeting therapy is the most common approach to immunotherapy and cellular therapy for multiple myeloma (MM). Three major agents, CAR-T cells, bispecific antibodies, and ADC have been developed as novel therapeutic agents. CAR-T therapy showed favorable efficacy in the treatment of relapsed and refractory MM (RR MM) and was tried in early lines of therapy. Similarly, bispecific antibodies targeting BCMA or other targets have also shown promising effects in treatment of RR MM, and have been now tested in combination with other agents. Although issues such as poor fitness or exhaustion of T cells and increased susceptibility to viral infection remain to be fully resolved, novel immunotherapies and cellular therapies should further improve the prognosis of patients with RR MM.

Single-cell sequencing reveals the correlation of aggrephagy signaling and multiple myeloma immune microenvironment composition.

Aggrephagy, a type of autophagy, degrades the aggregation of misfolded protein in cells. However, the role of aggrephagy in multiple myeloma (MM) has not been fully demonstrated. In this study, we first investigated the correlation between aggrephagy signaling, MM immune microenvironment composition and disease prognosis. Single-cell RNA-seq data, including the expression profiles of 12,187 single cells from seven MM bone marrow (BM) and seven healthy BM samples, were analyzed by non-negative matrix factorization for 44 aggrephagy-related genes. Bulk RNA-seq cohorts from the Gene Expression Omnibus database were used to evaluate the prognostic value of aggrephagy-related immune cell subtypes and predict immune checkpoint blockade immunotherapeutic response in MM. Compared with healthy BM, MM BM exhibited different patterns of aggrephagy-related gene expression. In MM BM, macrophages, CD8+ T cells, B cells and natural killer cells could be grouped into four to nine aggrephagy-related subclusters. The signature of aggrephagy signaling molecule expression in the immune cells correlates with the patient's prognosis. Our investigation provides a novel view of aggrephagy signaling in MM tumor microenvironment cells, which might be a prognostic indicator and potential target for MM treatment.

Immune dysfunction prior to and during vaccination in multiple myeloma: a case study based on COVID-19.

Infection is the leading cause of death in multiple myeloma (MM). However, the cellular composition associated with immune dysfunction is not defined. We analyzed immune profiles in the peripheral blood of patients with MM (n = 28) and B-cell chronic lymphoproliferative disorders (n = 53) vs. health care practitioners (n = 96), using multidimensional and computational flow cytometry. MM patients displayed altered distribution of most cell types (41/56, 73%), particularly within the B-cell (17/17) and T-cell (20/30) compartments. Using COVID-19 as a case study, we compared the immune response to vaccination based on 64,304 data points generated from the analysis of 1099 longitudinal samples. MM patients showed limited B-cell expansion linked to lower anti-RBD and anti-S antibody titers after the first two doses and booster. The percentages of B cells and CD4+ T cells in the blood, as well as the absolute counts of B cells and dendritic cells, predicted vaccine immunogenicity at different time points. In contrast with the humoral response, the percentage and antigen-dependent differentiation of SARS-CoV-2-specific CD8+ T cells was not altered in MM patients. Taken together, this study defined the cellular composition associated with immune dysfunction in MM and provided biomarkers such as the B-cell percentage and absolute count to individualize vaccination calendars.

Evaluation of interleukin-18 levels in patients affected by multiple myeloma and monoclonal gammopathy of undetermined significance: analysis and review of the literature.

OBJECTIVE: Monoclonal gammopathy of undetermined significance (MGUS) is a preneoplastic disease that often precedes multiple myeloma. The multistep evolutionary pattern of multiple myeloma is driven by genetic instability, a pro-inflammatory and immunosuppressive microenvironment, and tumor growth. Inflammation has long been recognized as a factor in both the onset and progression of cancer. PATIENTS AND METHODS: In this study, interleukin-18 plasma levels were compared in patients with multiple myeloma and monoclonal gammopathy of undetermined significance, as well as in a group of healthy controls. RESULTS: Our study shows that monoclonal gammopathy of undetermined significance patients have lower levels of interleukin-18 than healthy controls (521.657 ± 168.493 pg/ml vs. 1,266.481 ± 658.091 pg/ml for controls, p < 0.001). Thus, we discovered a significant difference in interleukin-18 levels between multiple myeloma patients and controls (418.177 ± 197.837 pg/ml; p = 0.001). CONCLUSIONS: In our work, we identified a reduction of interleukin-18 in monoclonal gammopathies. Furthermore, in this paper, we aimed to evaluate the existing literature on the potential mechanisms of action of this pro-inflammatory cytokine in the development of these diseases.

Preclinical activity of allogeneic SLAMF7-specific CAR T-cells (UCARTCS1) in multiple myeloma.

BACKGROUND: Autologous BCMA-specific CAR T-cell therapies have substantial activity in multiple myeloma (MM). However, due to logistical limitations and BCMAlow relapses, there is a need for alternatives. UCARTCS1 cells are 'off-the-shelf' allogeneic CAR T-cells derived from healthy donors targeting SLAMF7 (CS1), which is highly expressed in MM cells. In this study, we evaluated the preclinical activity of UCARTCS1 in MM cell lines, in bone marrow (BM) samples obtained from MM patients and in an MM mouse model. METHODS: Luciferase-transduced MM cell lines were incubated with UCARTCS1 cells or control (non-transduced, SLAMF7/TCRαß double knock-out) T-cells at different effector to target ratios for 24 hours. MM cell lysis was assessed by bioluminescence. Anti-MM activity of UCARTCS1 was also evaluated in 29 BM samples obtained from newly diagnosed patients (n=10), daratumumab-naïve relapsed/refractory patients (n=10) and daratumumab-refractory patients (n=9) in 24-hour flow cytometry-based cytotoxicity assays. Finally, UCARTCS1 activity was assessed in mouse xenograft models. RESULTS: UCARTCS1 cells induced potent CAR-mediated, and dose-dependent lysis of both MM cell lines and primary MM cells. There was no difference in ex vivo activity of UCARTCS1 between heavily pretreated and newly diagnosed patients. In addition, efficacy of UCARTCS1 was not affected by SLAMF7 expression level on MM cells, proportion of tumor cells, or frequency of regulatory T-cells in BM samples obtained from MM patients. UCARTCS1 treatment eliminated SLAMF7+ non-malignant immune cells in a dose-dependent manner, however lysis of normal cells was less pronounced compared to that of MM cells. Additionally, durable anti-MM responses were observed with UCARTCS1 in an MM xenograft model. CONCLUSIONS: These results demonstrate that UCARTCS1 has potent anti-MM activity against MM cell lines and primary MM cells, as well as in an MM xenograft model and support the evaluation of UCARTCS1 in patients with advanced MM.

Genomic and immune determinants of resistance to daratumumab-based therapy in relapsed refractory multiple myeloma.

Targeted immunotherapy combinations, including the anti-CD38 monoclonal antibody (MoAb) daratumumab, have shown promising results in patients with relapsed/refractory multiple myeloma (RRMM), leading to a considerable increase in progression-free survival. However, a large fraction of patients inevitably relapse. To understand this, we investigated 32 relapsed MM patients treated with daratumumab, lenalidomide, and dexamethasone (Dara-Rd; NCT03848676). We conducted an integrated analysis using whole-genome sequencing (WGS) and flow cytometry in patients with RRMM. WGS before and after treatment pinpointed genomic drivers associated with early progression, including RPL5 loss, APOBEC mutagenesis, and gain of function structural variants involving MYC and chromothripsis. Flow cytometry on 202 blood samples, collected every 3 months until progression for 31 patients, revealed distinct immune changes significantly impacting clinical outcomes. Progressing patients exhibited significant depletion of CD38-positive NK cells, persistence of T-cell exhaustion, and reduced depletion of regulatory T cells over time. These findings underscore the influence of immune composition and daratumumab-induced immune changes in promoting MM resistance. Integrating genomics and flow cytometry unveiled associations between adverse genomic features and immune patterns. Overall, this study sheds light on the intricate interplay between genomic complexity and the immune microenvironment driving resistance to Dara-Rd in patients with RRMM.

IgG replacement in multiple myeloma.

T cell engagers (TCE) such as chimeric antigen receptor (CAR) T cell therapy and bispecific antibodies (BiAbs) for the treatment of multiple myeloma (MM) have significantly improved clinical outcomes, but have also raised awareness for ensuing post-treatment secondary immunodeficiency and hypogammaglobulinemia (HG). As patients with MM live longer, recurrent infections become a significant component of therapy-associated morbidity and mortality. Treatment of HG with immunoglobulin G replacement therapy (IgG-RT) has been a mainstay of the primary immunodeficiency (PI) world, and extrapolation to MM has recently started to show promising clinical outcomes. However, IgG-RT initiation, dosing, route, timing, monitoring, and management in MM has not been standardized in the setting of TCE. Progress in MM treatment will involve greater recognition and screening of underlying secondary immunodeficiency, identification of risk-stratification markers, optimizing IgG-RT management, and implementing other approaches to decrease the risk of infection. In this review, we summarize infection risk, risk of HG, and management strategies for IgG-RT in patients with relapsed MM after TCE.

Just scratching the surface: novel treatment approaches for multiple myeloma targeting cell membrane proteins.

A better understanding of the roles of the adaptive and innate immune systems in the oncogenesis of cancers including multiple myeloma (MM) has led to the development of novel immune-based therapies. B cell maturation antigen (BCMA), G protein-coupled receptor family C group 5 member D (GPRC5D) and Fc receptor-like protein 5 (FcRL5, also known as FcRH5) are cell-surface transmembrane proteins expressed by plasma cells, and have been identified as prominent immunotherapeutic targets in MM, with promising activity demonstrated in patients with heavily pretreated relapsed and/or refractory disease. Indeed, since 2020, antibody-drug conjugates, bispecific T cell engagers and autologous chimeric antigen receptor T cells targeting BCMA or GPRC5D have been approved for the treatment of relapsed and/or refractory MM. However, responses to these therapies are not universal, and acquired resistance invariably occurs. In this Review, we discuss the various immunotherapeutic approaches targeting BCMA, GPRC5D and FcRL5 that are currently either available or in clinical development for patients with MM. We also review the mechanisms underlying resistance to such therapies, and discuss potential strategies to overcome these mechanisms and improve patient outcomes.

[Construction of CD138-targeted chimeric antigen receptor- modified T cells and their effect in multiple myeloma therapy].

Objective: To construct a novel chimeric antigen receptor T (CAR-T) cell targeting CD138 and to investigate its cytotoxicity against myeloma cells. Methods: The hybridoma strain that can stably secrete the CD138 monoclonal antibody (mAb) was prepared and obtained through monoclonal antibody screening technology. The hybridoma strain cells were intraperitoneally injected into mice to produce ascites containing monoclonal antibodies, which were then collected and purified to obtain pure CD138 mAb. Further examinations were performed to assess the biological characteristics of CD138 mAb. The variable region sequence of this antibody was amplified through reverse transcription polymerase chain reaction and was used as the antigen recognition domain of CD138 CAR, which was subsequently expressed on the surface of T cells by lentiviral infection. Flow cytometry was employed to assess the phenotype of CD138 CAR-T cells. In vitro cytotoxicity and degranulation assays were performed to evaluate their antitumor effects. Results: ① We successfully prepared anti-human CD138 antibody hybridoma cell lines and screened a hybridoma cell strain, 5G2, which could persistently and stably secrete the anti-CD138 antibody. ② The purified CD138 (5G2) mAb can especially recognize CD138(+) cells with a binding affinity constant (K(D)) of 6.011×10(-9) mol/L and showed no significant binding activity with CD138(-) cells. ③The variable region sequence of the CD138 (5G2) antibody was obtained using molecular cloning technology, and CD138 (5G2) CAR was successfully constructed and expressed on T cells through lentivirus infection and, concurrently, demonstrated effective binding to recombinant human CD138 protein.④ The proliferation of T cells transduced with the CD138 (5G2) CAR was highly efficient. The phenotype analysis revealed that CD138 (5G2) CAR-T cells exhibited a greater tendency to differentiate into central memory T cells and memory stem T cells, with a reduced proportion of terminally differentiated effector memory subsets. ⑤CD138 (5G2) CAR-T cells demonstrated specific cytotoxicity against CD138(+) myeloma cell line H929, whereas CD138(-) cell line K562 remained unaffected. The percentage of residual H929 cells was (12.92±8.02) % after co-culturing with CD138 (5G2) CAR-T cells, while (54.25±15.79) % was left in the Vector-T group (E∶T=1∶2; P<0.001). ⑥Results of degranulation assays demonstrated a significant activation of CD138 (5G2) CAR-T cells after co-culture with the H929 cell line, whereas no significant activation was observed in Vector-T cells [ (25.78±3.35) % vs (6.13±1.30) %, P<0.001]. ⑦After co-culturing with CD138(+) cells, CD138 (5G2) CAR-T cells exhibited a significant increase in cytokine secretion compared to the Vector-T group [interleukin-2: (1 697.52±599.05) pg/ml vs (5.07±1.17) pg/ml, P<0.001; interferon-γ: (3 312.20±486.38) pg/ml vs (9.28±1.46) pg/ml, P<0.001; and tumor necrosis factor-α: (1 837.43±640.49) pg/ml vs (8.75±1.65) pg/ml, P<0.001]. However, no significant difference was observed in cytokine secretion levels between the two groups after co-culturing with CD138(-) cells. Conclusion: This study successfully prepared a novel monoclonal antibody against CD138, and CAR-T cells constructed with the antigen recognition domain derived from this 5G2 mAb demonstrated effective antitumor activity against myeloma cells. This can be used as a new option for the detection of the CD138 antigen and proposes a novel strategy for multiple myeloma immunotherapy.

Coexistence of double seropositivity for MPO antibody and anti-GBM antibody in ANCA-associated vasculitis concurrent with multiple myeloma: A case report.

RATIONALE: Immune-mediated vasculitis with 2 or more autoantibodies, for example, anti-proteinase-3, combined with anti-myeloperoxidase (MPO) or anti-glomerular basement membrane (GBM) antibodies, is extremely unusual. Furthermore, the coexistence of autoimmune vasculitis and hematological malignancies is uncommon. Herein, we describe a case of double-seropositive anti-neutrophil cytoplasmic antibody (ANCA) vasculitis with multiple myeloma. PATIENT CONCERNS: A 79-year-old Asian man presented with persistent leg edema and kidney dysfunction. His kidney function rapidly decreased, and serologic test results showed higher titers of the anti-MPO antibody (54.7 IU/mL) and anti-GBM antibodies (>200 IU/mL). Additionally, the clinical features showed the possibility of monoclonal gammopathy with anemia and hyperglobulinemia. We performed kidney and bone marrow biopsy. Serum protein electrophoresis and immunofixation revealed no significant differences, but the results of the bone marrow smear were compatible with those of myeloma with 15% plasmacytosis. However, kidney biopsy showed diffuse crescentic glomerulonephritis without deposition of the immune complex or kappa/lambda chain. DIAGNOSES AND INTERVENTIONS: Finally, the patient was diagnosed with double-seropositive ANCA-associated glomerulonephritis and multiple myeloma. Given the patient's performance status, we initiated low-dose steroid pulse therapy, followed by conservative management. OUTCOMES: While the pulmonary lesions showed improvement, the kidney function did not regain its previous state, prompting the initiation of kidney replacement therapy by hemodialysis. There has been a decrease in the levels of anti-GBM and anti-MPO antibodies since the initial diagnosis. LESSONS: This case elucidates the complex interplay between ANCA-associated glomerulonephritis and hematologic malignancy and emphasizes the need for a nuanced treatment strategy considering its multifaceted clinical presentation.

Toll-like receptor signaling in multiple myeloma cells promotes the expression of pro-survival genes B-cell lymphoma 2 and MYC and modulates the expression of B-cell maturation antigen.

Infections are common in plasma cell cancer multiple myeloma (MM) due to disease-related immune deficiencies and cancer treatment. Myeloma cells express Toll-like receptors (TLRs), and TLR activation has been shown to induce proliferative and pro-survival signals in cancer cells. MM is a complex and heterogeneous disease, and expression levels of TLRs as well as downstream signaling components are likely to differ between patients. Here, we show that in a large cohort of patients, TLR1, TLR4, TLR6, TLR9, and TLR10 are the most highly expressed in primary CD138+ cells. Using an MM cell line expressing TLR4 and TLR9 as a model, we demonstrate that TLR4 and TLR9 activation promoted the expression of well-established pro-survival and oncogenes in MM such as MYC, IRF4, NFKB, and BCL2. TLR4 and TLR9 activation inhibited the efficacy of proteasome inhibitors bortezomib and carfilzomib, drugs used in the treatment of MM. Inhibiting the autophagosome-lysosome protein degradation pathway by hydroxychloroquine (HCQ) diminished the protective effect of TLR activation on proteasome inhibitor-induced cytotoxicity. We also found that TLR signaling downregulated the expression of TNFRSF17, the gene encoding for B-cell maturation antigen (BCMA). MYC, BCL2, and BCL2L1 were upregulated in approximately 50% of primary cells, while the response to TLR signaling in terms of TNFRSF17 expression was dichotomous, as an equal fraction of patients showed upregulation and downregulation of the gene. While proteasome inhibitors are part of first-line MM treatment, several of the new anti-MM immune therapeutic drugs target BCMA. Thus, TLR activation may render MM cells less responsive to commonly used anti-myeloma drugs.

Bispecific Antibody Use in Patients With Lymphoma and Multiple Myeloma.

This article endeavors to navigate the clinical journey of bispecific antibodies (BsAbs), from elucidating common toxicities and management strategies to examining novel agents and broadening access in community health care. These drugs, commonly through T-cell activation, result in shared adverse events such as cytokine release syndrome and immune effector cell-associated neurotoxicity syndrome. Variations in target antigens and designs, however, might introduce unique toxicities for different BsAbs, warranting specific management approaches. Recent US Food and Drug Administration approvals of BsAbs targeting CD3+ T cells linked to CD20 for non-Hodgkin lymphoma and to B-cell maturation antigen or GPRC5D for multiple myeloma have transformed the treatment landscape for hematologic malignancies. Emerging new agents promise further enhancement and safety, exploring novel antigen targets, innovative structures such as trispecific antibodies, and the engagement of diverse immune cells. Simultaneously, the expansion of BsAbs into community practices is underway, demanding a multifaceted strategy that encompasses educational initiatives, operational adaptations, and collaborative frameworks. This ensures comprehensive treatment access, allowing every patient, irrespective of geographical or socioeconomic status, to benefit from these advancements in cancer therapy.

Bispecific Antibodies for Multiple Myeloma: Recent Advancements and Strategies for Increasing Their Efficacy.

The treatment options for multiple myeloma (MM) have undergone significant transformation with the advent of immunotherapy. Novel therapies that focus on tumor antigens now drive advances in MM research. Bispecific antibodies (bsAbs) leverage revolutionary advances in bioengineering techniques and embody the second generation of antibody-based tumor therapy. Recent studies on bsAbs in relapsed/refractory MM cases have revealed remarkable efficacy and acceptable safety profiles. The approval of elranatamab and teclistamab represents the next step in the development of bsAbs for the treatment of MM. This review article addresses the antigen targeting, efficacy, safety, and strategies in the application of bsAbs against treatment-resistant MM, with a focus on clinical trials and real-world data.

Absolute Lymphocyte Count and Outcomes of Multiple Myeloma Patients Treated with Idecabtagene Vicleucel: The US Myeloma Immunotherapy Consortium Real- World Experience.

Idecabtagene vicleucel (ide-cel) has shown impressive efficacy in relapsed/refractory multiple myeloma (RRMM). This study aimed to investigate the impact of absolute lymphocyte count (ALC) on the survival outcomes of RRMM patients treated with standard of care (SOC) ide-cel. Data were collected retrospectively from 11 institutions in the U.S. Impact of ALC parameters including pre-apheresis (pre-A), pre-lymphodepletion (pre-LD), absolute and percent difference from pre-A to pre-LD on clinical outcomes after ide-cel were examined using survival analysis. A new ALC profile was created based on univariate analysis that comprises 3 groups: normal (≥1 × 109/L) pre-LD ALC (LDN), low (<1 × 109/L) pre-LD ALC (LDL) + percent reduction <37.5 (%RL), and LDL ALC + percent reduction ≥37.5 (%RH). A total of 214 SOC ide-cel recipients were included in this analysis. The median patient age was 64 years (interquartile range [IQR], 57 to 69 years), median number of prior therapies was 6 (IQR, 5 to 9), and median duration of follow-up was 5.4 months (IQR, 2.1 to 8.3 months). Most patients had both low pre-A ALC (75.3%) and pre-LD ALC (77.2%), and the reduction from pre-A to pre-LD (median, .65 to .55 × 109/L) was statistically significant. Univariate analysis showed that the LDL + %RH group had significantly worse progression-free survival (PFS) and overall survival (OS) compared to the LDL + %RL and LDN ALC groups (6-month PFS: 40% versus 67.6% and 60.9%; 6-month OS: 69.5% versus 87% and 94.3%). In multivariable analysis, after adjusting for age, performance status, cytogenetic risk, use of bridging therapy, and extramedullary disease, PFS did not maintain its statistical significance; however, OS remained significantly worse for LDL + %RH group compared to the LDN ALC group (hazard ratio [HR], 4.3; 95% confidence interval [CI], 1.1 to 17), but the difference between the LDL + %RH versus %RL groups was not statistically significant (HR, 1.7; 95% CI, .8 to 4.0). Our findings indicate that low pre-LD ALC with high %R from pre-A to pre-LD was associated with inferior survival outcomes, particularly OS, in patients who received SOC ide-cel.

[Development of novel bispecific antibody therapy for multiple myeloma].

Over the past decade, new therapeutic modalities have markedly improved clinical outcomes for patients with multiple myeloma. Recently, immunotherapy using both bispecific antibodies (BsAb) and chimeric antigen receptor T cells (CAR-T cells) has induced further anti-myeloma responses. Different agents must be combined to overcome the heterogeneity of myeloma cell clones, and new modalities for the treatment of refractory myeloma must also be developed to strengthen therapeutic effects. We have developed a novel BiTE (bispecific T-cell engager)-based modality, referred to as bridging-BiTE (B-BiTE). B-BiTE is able to bind to both an Fc domain of a human immunoglobulin G monoclonal antibody (mAb) and the human CD3 molecule. This enables rapid generation of a mAb/B-BiTE complex and safely induces dual-lymphoid activation of both human T cells and NK cells against myeloma cells. Importantly, sequential immunotherapy using two different mAb/B-BiTE complexes can produce deep and durable anti-myeloma responses. To further advance treatment of multiple myeloma, it is important to determine how to combine and sequence immunotherapy with other agents while considering management of unique adverse events caused by activated immune cells.

Progression of monoclonal gammopathy of undetermined significance to multiple myeloma is associated with enhanced translational quality control and overall loss of surface antigens.

BACKGROUND: Despite significant advancements in treatment strategies, multiple myeloma remains incurable. Additionally, there is a distinct lack of reliable biomarkers that can guide initial treatment decisions and help determine suitable replacement or adjuvant therapies when relapse ensues due to acquired drug resistance. METHODS: To define specific proteins and pathways involved in the progression of monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma (MM), we have applied super-SILAC quantitative proteomic analysis to CD138 + plasma cells from 9 individuals with MGUS and 37 with MM. RESULTS: Unsupervised hierarchical clustering defined three groups: MGUS, MM, and MM with an MGUS-like proteome profile (ML) that may represent a group that has recently transformed to MM. Statistical analysis identified 866 differentially expressed proteins between MM and MGUS, and 189 between MM and ML, 177 of which were common between MGUS and ML. Progression from MGUS to MM is accompanied by upregulated EIF2 signaling, DNA repair, and proteins involved in translational quality control, whereas integrin- and actin cytoskeletal signaling and cell surface markers are downregulated. CONCLUSION: Compared to the premalignant plasma cells in MGUS, malignant MM cells apparently have mobilized several pathways that collectively contribute to ensure translational fidelity and to avoid proteotoxic stress, especially in the ER. The overall reduced expression of immunoglobulins and surface antigens contribute to this and may additionally mediate evasion from recognition by the immune apparatus. Our analyses identified a range of novel biomarkers with potential prognostic and therapeutic value, which will undergo further evaluation to determine their clinical significance.

miR-34a promotes the immunosuppressive function of multiple myeloma-associated macrophages by dampening the TLR-9 signaling.

BACKGROUND: Promising outcomes have been observed in multiple myeloma (MM) with the use of immunotherapies, specifically chimeric antigen receptor T (CAR-T) cell therapy. However, a portion of MM patients do not respond to CAR-T therapy, and the reasons for this lack of response remain unclear. The objective of this study was to investigate the impact of miR-34a on the immunosuppressive polarization of macrophages obtained from MM patients. METHODS: The levels of miR-34a and TLR9 (Toll-like receptor 9) were examined in macrophages obtained from both healthy individuals and patients with MM. ELISA was employed to investigate the cytokine profiles of the macrophage samples. Co-culture experiments were conducted to evaluate the immunomodulatory impact of MM-associated macrophages on CAR-T cells. RESULTS: There was an observed suppressed activation of macrophages and CD4+ T lymphocytes in the blood samples of MM patients. Overexpression of miR-34a in MM-associated macrophages dampened the TLR9 expression and impaired the inflammatory polarization. In both the co-culture system and an animal model, MM-associated macrophages suppressed the activity and tumoricidal effect of CAR-T cells in a miR-34a-dependent manner. CONCLUSION: The findings imply that targeting the macrophage miR-34a/TLR9 axis could potentially alleviate the immunosuppression associated with CAR-T therapy in MM patients.

T-cell exhaustion in multiple myeloma.

INTRODUCTION: Chimeric Antigen Receptor (CAR) T-cells and Bispecific Antibodies (BsAb) are the leading platforms for redirecting the immune system against cells expressing the specific antigen, revolutionizing the treatment of hematological malignancies, including multiple myeloma (MM). In MM, drug-resistant relapses are the main therapy-limiting factor and the leading cause of why the disease is still considered incurable. T-cell-engaging therapies hold promise in improving the treatment of MM. However, the effectiveness of these treatments may be hindered by T-cell fitness. T-cell exhaustion is a condition of a gradual decline in effector function, reduced cytokine secretion, and increased expression of inhibitory receptors due to chronic antigen stimulation. AREAS COVERED: This review examines findings about T-cell exhaustion in MM in the context of T-cell redirecting BsAbs and CAR-T treatment. EXPERT OPINION: The fitness of T-cells has become an important factor in the development of T-cell redirecting therapies. The way T-cell exhaustion relates to these therapies could affect the further development of CAR and BsAbs technologies, as well as the strategies used for clinical use. Therefore, this review aims to explore the current understanding of T-cell exhaustion in MM and its relationship to these therapies.