Molecular and immunological mechanisms of clonal evolution in multiple myeloma

The role of non-malignant B cells in malignant hematologic diseases

The tumor microenvironment (TME) represents a heterogeneous, complicated ecosystem characterized by intricate interactions between tumor cells and immune cells. During the past decade, immune cells especially T cells were found to play an important role in the progression of tumor and many related immune checkpoints drugs were created. In recent years, more and more scientists revealed the critical role of B-cells within the TME, particularly various populations of non-malignant B cells. Some studies indicated that non-malignant B cells may exert a 'double-edged sword' role in solid tumors. However, there has been comparatively less focus on the role of non-malignant B cells in hematologic malignancies. In this review, we characterized the development of B cells and summarized its functions of antitumor immunity within TME, with an emphasis on elucidating the roles and potential mechanisms of non-malignant B cells in the progression of hematologic diseases including classical Hodgkin's lymphoma, non-Hodgkin's B-cell lymphoma, non-Hodgkin's T-cell lymphoma, leukemia and multiple myeloma.

Relapsed/refractory multiple myeloma: standard of care management of patients in the Gulf region

Clinical management of patients with relapsed/refractory multiple myeloma (RRMM) can be challenging, whereby each relapse is associated with progressively poorer outcomes. In addition, changes in disease biology and patient characteristics hamper treatment strategies in this setting, as do toxicities accumulated across previous lines of therapy. The availability of several new treatment classes has brought about improvements in outcomes, but with median survival in the RRMM setting at only ~32 months, a review of current standard of care treatments and considerations for optimizing care in this setting is warranted. Here, we discuss our preferred approach to treating patients with RRMM, based on our collective experience across the Gulf region. We present position statements for the treatment of lenalidomide-sensitive and -refractory patients, as well as for those patients experiencing late relapse. We discuss the major impact that anti-CD38 agents daratumumab and isatuximab have had on the management of RRMM, which is reflected in our preferred use of daratumumab-based regimens across the lenalidomide-sensitive and -refractory settings. For late-relapse settings, we discuss how bispecific antibodies and chimeric antigen receptor [CAR]-T cells are among the biggest breakthroughs in recent years, achieving excellent responses in triple-class exposed patients. While the use of these agents is not yet widespread in the Gulf region, we advocate their use where available and discuss strategies to manage and minimize common toxicities and adverse events associated with their use.

Enhancing T cell cytotoxicity in multiple myeloma with bispecific αPD-L1 × αCD3 T cell engager-armed T cells and low-dose bortezomib therapy

Multiple myeloma (MM) is an incurable plasma cell malignancy characterized by frequent relapse due to acquired treatment resistance, underscoring the need for innovative therapies, particularly for relapsed cases. This study explores the effects of low-dose bortezomib (BTZ) on programmed death ligand 1 (PD-L1) expression in MM cell lines and its potential to enhance T cell-mediated anti-tumor responses. Utilizing this PD-L1 upregulation, we employed bispecific αPD-L1 × αCD3 T cell engager-armed T cells (BATs) to block PD-L1 signaling and activate T cells. Flow cytometry confirmed that BATs selectively bound CD3 on T cells and PD-L1 on cancer cells, inducing T cell activation and proliferation without directly affecting cancer cell viability. BATs' cytotoxic activity was evaluated in MM cell lines with or without BTZ-induced PD-L1 expression. While KMS-12-PE cells showed no significant response, BATs significantly increased cell death in L363 cells, with further enhancement by BTZ. In RPMI-8226 cells, BATs demonstrated robust cytotoxicity, further amplified by BTZ. These results suggest that BATs, particularly in combination with BTZ, represent a promising strategy for treating MM, including bortezomib-resistant cases.

Multiple Myeloma Insights from Single-Cell Analysis: Clonal Evolution, the Microenvironment, Therapy Evasion, and Clinical Implications

Multiple myeloma (MM) is a complex and heterogeneous hematologic malignancy characterized by clonal evolution, genetic instability, and interactions with a supportive tumor microenvironment. These factors contribute to treatment resistance, disease progression, and significant variability in clinical outcomes among patients. This review explores the mechanisms underlying MM progression, including the genetic and epigenetic changes that drive clonal evolution, the role of the bone marrow microenvironment in supporting tumor growth and immune evasion, and the impact of genomic instability. We highlight the critical insights gained from single-cell technologies, such as single-cell transcriptomics, genomics, and multiomics, which have enabled a detailed understanding of MM heterogeneity at the cellular level, facilitating the identification of rare cell populations and mechanisms of drug resistance. Despite the promise of advanced technologies, MM remains an incurable disease and challenges remain in their clinical application, including high costs, data complexity, and the need for standardized bioinformatics and ethical considerations. This review emphasizes the importance of continued research and collaboration to address these challenges, ultimately aiming to enhance personalized treatment strategies and improve patient outcomes in MM.

Targeting enolase 1 reverses bortezomib resistance in multiple myeloma through YWHAZ/Parkin axis

BACKGROUND

Enolase 1 (ENO1) is a conserved glycolytic enzyme that regulates glycolysis metabolism. However, its role beyond glycolysis in the pathophysiology of multiple myeloma (MM) remains largely elusive. Herein, this study aimed to elucidate the function of ENO1 in MM, particularly its impact on mitophagy under bortezomib-induced apoptosis.

METHODS

The bone marrow of clinical MM patients and healthy normal donors was used to compare the expression level of ENO1. Using online databases, we conducted an analysis to examine the correlation between ENO1 expression and both clinicopathological characteristics and patient outcomes. To investigate the biological functions of ENO1 in MM and the underlying molecular mechanisms involved, we conducted the following experiment: construction of a subcutaneous graft tumor model, co-immunoprecipitation, western blot, quantitative real-time polymerase chain reaction, immunohistochemistry, flow cytometry, and cell functional assays.

RESULTS

ENO1 was identified as an unfavorable prognostic factor in MM. ENO1 knockdown suppresses tumorigenicity and causes cell cycle arrest. Inhibition of ENO1-regulated mitophagy sensitizes tumor cells to apoptosis. ENO1 enhanced the stability of the YWHAZ protein by increasing the acetylation of lysine in YWHAZ while antagonizing its ubiquitination, which in turn promoted mitophagy. HDAC6 mediates the deacetylation of YWHAZ by deacetylating the K138 site of YWHAZ. Inhibition of HDAC6 increased YWHAZ acetylation and decreased YWHAZ ubiquitination. Furthermore, combination treatment with bortezomib and pharmaceutical agents targeting ENO1 has synergistic anti-MM effects both in vivo and in vitro.

CONCLUSION

Our data suggest that ENO1 promotes MM tumorigenesis and progression. ENO1 activates mitophagy by promoting the stability of YWHAZ and inhibits apoptosis and thus, leads to the drug resistance. ENO1-dependent mitophagy promotes MM proliferation and suppresses the level of bortezomib-induced apoptosis. Inhibition of ENO1 may represent a potential strategy to reverse the resistance of MM to bortezomib.

CD34+ and CD34- MM cells show different immune-checkpoint molecule expression profiles: high expression of CD112 and CD137 ligand on CD34+ MM cells

Despite the introduction of new drugs, multiple myeloma (MM) still remains incurable. We previously reported that CD34+ MM cells, which are clonogenic and self-renewing, are therapy-resistant and persist as a major component of minimal residual disease, expanding during relapse. To investigate the effects of immunotherapies such as immune-checkpoint inhibitors, CAR-T therapy, and bispecific antibodies on CD34+ MM cells, we analyzed immune profiles of both MM cells and T cells from MM patients using microarrays and flow cytometry. Ingenuity pathway analysis revealed 14 out of 289 canonical pathways were more active in CD34+ MM cells compared to CD34- cells, many of which were involved in inflammation and immune responses. Notably, PD-1 signaling-related genes were highly expressed in CD34+ MM cells. Among 10 immune-checkpoint molecules, CD34+ cells more frequently expressed CD112, CD137L, CD270, CD275, and GAL9 than CD34- cells in both newly diagnosed and relapsed/resistant patients. In addition, CD4+ and CD8+ T cells more frequently expressed TIGIT and CD137, suggesting that CD112/TIGIT and CD137L/CD137 interactions may suppress T-cell activity against CD34+ MM cells. Furthermore, our finding of higher FcRH5 expression on CD34+ MM cells is encouraging for future research into the efficacy of FcRH5-targeted therapy in MM.

The Genetic and Molecular Drivers of Multiple Myeloma: Current Insights, Clinical Implications, and the Path Forward

Background

Multiple myeloma (MM) is a hematological malignancy characterized by the clonal proliferation of malignant plasma cells within the bone marrow. The disease's complexity is underpinned by a variety of genetic and molecular abnormalities that drive its progression.

Methods

This review was conducted through a state-of-The-art literature search, primarily utilizing PubMed to gather peer-reviewed articles. We focused on the most comprehensive and cited studies to ensure a thorough understanding of the genetic and molecular landscapes of MM.

Results

We detail primary and secondary alterations such as translocations, hyperdiploidy, single nucleotide variants (SNVs), copy number alterations (CNAs), gene fusions, epigenetic modifications, non-coding RNAs, germline predisposing variants, and the influence of the tumor microenvironment (TME). Our analysis highlights the heterogeneity of MM and the challenges it poses in treatment and prognosis, emphasizing the distinction between driver mutations, which actively contribute to oncogenesis, and passenger mutations, which arise due to genomic instability and do not contribute to disease progression.

Conclusion & Future Perspectives

We report key controversies and challenges in defining the genetic drivers of MM, and examine their implications for future therapeutic strategies. We discuss the importance of systems biology approaches in understanding the dependencies and interactions among these alterations, particularly highlighting the impact of double and triple-hit scenarios on disease outcomes. By advancing our understanding of the molecular drivers and their interactions, this review sets the stage for novel therapeutic targets and strategies, ultimately aiming to improve clinical outcomes in MM patients.

Biomarker-directed therapy in multiple myeloma

PURPOSE OF REVIEW

Multiple myeloma is currently treated with a one-size-fits-all approach despite significant heterogeneity in patient outcomes and disease molecular constitution. A personalised approach would tailor therapy to unique patient or disease characteristics.

RECENT FINDINGS

Well established prognostic biomarkers such as cytogenetic risk and patient frailty status are being evaluated as potential predictive biomarkers. Specifically, treatment intensity can be augmented in high-risk patients or conversely attenuated in those at lower risk or lower ability to withstand treatment toxicities. Alternatively, targeted therapy can be rationally designed to exploit vulnerable pathways in myeloma cells as identified using predictive biomarkers. The t(11;14) translocation, found in approximately 15-20% of myeloma cases, is a leading biomarker for response to BCL-2 inhibitors such as venetoclax.

SUMMARY

Active research efforts exploring venetoclax combination therapies, as well as new generation BCL-2 inhibitors are underway. Following the development of venetoclax, numerous other cellular pathways are under investigation as candidate predictive biomarkers to rationally inform newer targeted therapies in myeloma.

DNp73 enhances tumor progression and immune evasion in multiple myeloma by targeting the MYC and MYCN pathways

Introduction

Multiple myeloma (MM) is an incurable hematological malignancy with high chromosome instability and heavy dependence on the immunosuppressive bone marrow microenvironment. P53 mutations are adverse prognostic factors in MM; however, clinically, some patients without P53 mutations also exhibit aggressive disease progression. DNp73, an inhibitor of TP53 tumor suppressor family members, drives drug resistance and cancer progression in several solid malignancies. Nevertheless, the biological functions of DNp73 and the molecular mechanisms in myelomagenesis remain unclear.

Methods

The effects of DNp73 on proliferation and drug sensitivity were assessed using flow cytometry and xenograft models. To investigate the mechanisms of drug resistance, RNA-seq and ChIP-seq analyses were performed in MM cell lines, with validation by Western blot and RT-qPCR. Immunofluorescence and transwell assays were used to assess DNA damage and cell invasion in MM cells. Additionally, in vitro phagocytosis assays were conducted to confirm the role of DNp73 in immune evasion.

Results

Our study found that activation of NF-κB-p65 in multiple myeloma cells with different p53 mutation statuses upregulates DNp73 expression at the transcriptional level. Forced expression of DNp73 promoted aggressive proliferation and multidrug resistance in MM cells. Bulk RNA-seq analysis was conducted to assess the levels of MYCN, MYC, and CDK7. A ChIP-qPCR assay was used to reveal that DNp73 acts as a transcription factor regulating MYCN gene expression. Bulk RNA-seq analysis demonstrated increased levels of MYCN, MYC, and CDK7 with forced DNp73 expression in MM cells. A ChIP-qPCR assay revealed that DNp73 upregulates MYCN gene expression as a transcription factor. Additionally, DNp73 promoted immune evasion of MM cells by upregulating MYC target genes CD47 and PD-L1. Blockade of the CD47/SIRPα and PD-1/PD-L1 signaling pathways by the SIRPα-Fc fusion protein IMM01 and monoclonal antibody atezolizumab significantly restored the anti-MM activity of macrophages and T cells in the microenvironment, respectively.

Discussion

In summary, our study demonstrated for the first time that the p53 family member DNp73 remarkably induces proliferation, drug resistance, and immune escape of myeloma cells by directly targeting MYCN and regulating the MYC pathway. The oncogenic function of DNp73 is independent of p53 status in MM cells. These data contribute to a better understanding of the function of TP53 and its family members in tumorigenesis. Moreover, our study clarified that DNp73 overexpression not only promotes aggressive growth of tumor cells but, more importantly, promotes immune escape of MM cells through upregulation of immune checkpoints. DNp73 could serve as a biomarker for immunotherapy targeting PD-L1 and CD47 blockade in MM patients.

Drug resistance in human cancers - Mechanisms and implications

Cancers have complex etiology and pose a significant impact from the health care perspective apart from the socio-economic implications. The enormity of challenge posed by cancers can be understood from the fact that clinical trials for cancer therapy has yielded minimum potential promises compared to those obtained for other diseases. Surgery, chemotherapy and radiotherapy continue to be the mainstay therapeutic options for cancers. Among the challenges posed by these options, induced resistance to chemotherapeutic drugs is probably the most significant contributor for poor prognosis and ineffectiveness of the therapy. Drug resistance is a property exhibited by almost all cancer types including carcinomas, leukemias, myelomas, sarcomas and lymphomas. The mechanisms by which drug resistance is induced include the factors within the tumor microenvironment, mutations in the genes responsible for drug metabolism, changes in the surface drug receptors and increased drug efflux. We present here comprehensively the drug resistance in cancers along with their mechanisms. Also, apart from resistance to regularly used chemotherapeutic drugs, we present resistance induction to new generation therapeutic agents such as monoclonal antibodies. Finally, we have discussed the experimental approaches to understand the mechanisms underlying induction of drug resistance and potential ways to mitigate induced drug resistance.

Exploring natural killer cell-related biomarkers in multiple myeloma: a novel nature killer cell-related model predicting prognosis and immunotherapy response using single-cell study

BACKGROUND

Natural killer cells (NKs) may be involved in multiple myeloma (MM) progression. The present study elucidated the correlation between NKs and the progression of MM using single-cell binding transcriptome probes to identify NK cell-related biomarkers.

METHODS

Single-cell analysis was performed including cell and subtype annotation, cell communication, and pseudotime analysis. Hallmark pathway enrichment analysis of NKs and NKs-related differentially expressed genes (DEGs) were conducted using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and protein-protein interaction (PPI) networks. Then, a risk model was structured based on biomarkers identified through univariate Cox regression analysis and least absolute shrinkage and selection operator regression analysis and subsequently validated. Additionally, correlation of clinical characteristics, gene set enrichment analysis, immune analysis, regulatory network, and drug forecasting were explored.

RESULTS

A total of 13 cell clusters were obtained and annotated, including 8 cell populations that consisted of NKs. Utilizing 123 PPI network node genes, 8 NK-related DEGs were selected to construct a prognostic model. Immune cell infiltration results suggested that 11 immune cells exhibited marked differences in the high and low-risk groups. Finally, the model was used to screen potential drug targets to enhance immunotherapy efficacy.

CONCLUSION

A new prognostic model for MM associated with NKs was constructed and validated. This model provides a fresh perspective for predicting patient outcomes, immunotherapeutic response, and candidate drugs.