Immune System Alterations in Multiple Myeloma: Molecular Mechanisms and Therapeutic Strategies to Reverse Immunosuppression

Practical guidance on the prevention and management of infection in multiple myeloma patients: A case-based approach

The risk of infection in multiple myeloma patients is significant, due to immune dysfunction secondary to myeloma, immunosenescence and age-related comorbidities, given the elderly myeloma patient demographic. Newer treatments, despite providing unprecedented improvements in disease-control, have further elevated infection risk. This risk is so substantial that we are approaching a period where a subset of older myeloma patients may be more likely to die secondary to infectious complications imposed by redirected T-cell therapy rather than from myeloma. As a result, it is essential to provide myeloma patients with the appropriate prophylaxis and monitoring against infection. In this review, we discuss disease-related, patient-related and treatment-related reasons for the increased infection risk in myeloma patients, and how to both prevent and manage this risk through creating a dynamic, infection prevention plan that is personalised to the individual patient.

A novel allele of B(A) blood group detected in a donor and a patient during a retrospective review of ABO group anomalies in a tertiary hospital

BACKGROUND

ABO discrepancies, inconclusive results between forward and reverse typing, are one of the significant challenges encountered in transfusion medicine. Their frequency and etiologies can vary among ethnicities. This study aimed to characterize ABO discrepancies in a Thai population.

METHODS

We conducted a retrospective review of 285,450 donor and 258,780 patient samples for ABO discrepancies, which were categorized into five groups, as described below. The serological ABO grouping was performed using an automated system, and further serological techniques were used in the discrepancy cases. Additionally, sequencing was used to examine the genetic background of the B(A) phenotype detected during the retrospective review.

RESULTS

ABO discrepancies were identified in 396 patients (0.15 %) and 74 blood donors (0.03 %). Among the patients, the most frequent cause was ABO mismatch stem cell transplantation (198; 50 %). The remaining 198 discrepancy cases (198/258,780; 0.08 %) were categorized into five groups: weak/missing red cell reactivity, extra red cell reactivity, mixed-field, weak/missing serum reactivity, and extra serum reactivity, accounting for 17.17 %, 0.51 %, 29.29 %, 28.79 %, and 24.24 %, respectively. For the blood donors, the percentages were 48.65 %, 2.70 %, 2.70 %, 37.84 %, and 8.11 %, respectively. We also identified the B(A) phenotype in one patient and two blood donors. The sequencing study identified allele variants of c.467 C>T, c.796 C>A, c.803 G>C, and c.930 G>A in exon 7, which was a novel allele.

CONCLUSION

ABO discrepancies were distinct between donors and patients even in the same ethnicity. This finding highlighted the influence of the patient's conditions and therapy on the anomalous ABO typing. Additionally, the B(A) individuals identified in this study carried identical genetic alterations that differed from all antecedent alleles of the B(A) phenotype.

Prehabilitation to improve function after autologous stem cell transplantation: A pilot randomized controlled trial (PIRATE)

PURPOSE

Exercise and nutrition interventions are not part of routine care for those undergoing autologous stem cell transplant (autoSCT). We aimed to explore estimates of effect, safety and feasibility of multidisciplinary prehabilitation for improving physical capacity after autoSCT.

METHODS

This single-blinded, parallel, two-armed pilot randomized trial included adults receiving autoSCT. Participants were randomized to twice-weekly, supervised, tailored exercise and fortnightly telephone-based nutrition education, for up to 8-weeks prior to autoSCT (n = 11) or usual care (n = 11). Blinded assessments occurred at baseline (T0), pre-transplant (T1), and 4-weeks post-transplant (T2). The primary outcome was physical capacity (6-min walk test). Secondary measures included recruitment rate, adverse events, exercise adherence, physical status, nutritional status, health-related quality of life, and health service outcomes.

RESULTS

Positive estimates of effect for walking capacity in favour of the experimental group were demonstrated at T2 (MD + 141 m, 95% CI 24 to 257 m). There was high recruitment (81%) and adherence and no major adverse events. At T2 there were large estimates of effect favoring the experimental group for higher bodyweight, and less dyspnea and gastrointenstinal symptoms. There were no between-group differences in other outcomes.

CONCLUSION

Prehabilitation is safe, feasible and may improve walking capacity after autoSCT. Findings support a future fully-scaled trial of prehabilitation for autoSCT.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12620000496910. Registered April 20, 2020.

The Evolving Role of Checkpoint Inhibitors in Multiple Myeloma

Multiple myeloma (MM) is a plasma cell dyscrasia characterized by production of abnormal levels of a monoclonal immunoglobulin or plasma cell deposition that leads to end organ destruction. The disease remains incurable despite advances in combination treatments with classes of medications that include proteosome inhibitors, immunomodulating agents, monoclonal antibodies, small molecule inhibitors, alkylating agents, T-cell-based immunotherapies, and others. Checkpoint inhibitors (CKP-I), though showing robust efficacy in solid tumor and lymphoma, have had limited success as single agents in the treatment of MM. Furthermore, early FDA holds on trials involving CKP-I in myeloma led to diminished enrollment and data on its potential use. Nevertheless, clearer understanding of the mechanisms of immune dysregulation and unique bone marrow biology in the pathophysiology of MM have opened the opportunity for future uses of CKP-I in multiple myeloma. Herein we provide a comprehensive review of the immunologic basis of multiple myeloma, preclinical and published data from trials utilizing CKP-I in MM patients, and future targets in CKP-I development that may provide promising opportunities in the treatment of MM.

New horizons in our understanding of precursor multiple myeloma and early interception

Multiple myeloma is an incurable plasma cell malignancy that evolves over decades through the selection and malignant transformation of monoclonal plasma cells. The evolution from precursor states to symptomatic disease is characterized by an increasing complexity of genomic alterations within the plasma cells and a remodelling of the microenvironment towards an immunosuppressive state. Notably, in patients with advanced disease, similar mechanisms of tumour escape and immune dysfunction mediate resistance to modern T cell-based therapies, such as T cell-engaging bispecific antibodies and chimeric antigen receptor (CAR)-T cells. Thus, an increasing number of clinical trials are assessing the efficiency and safety of these therapies in individuals with newly diagnosed multiple myeloma and high-risk smoldering multiple myeloma. In this Review, we summarize the current knowledge about tumour intrinsic and extrinsic processes underlying progression from precursor states to symptomatic myeloma and discuss the rationale for early interception including the use of T cell-redirecting therapies.

Multiple myeloma long-term survivors exhibit sustained immune alterations decades after first-line therapy

The long-term consequences of cancer and its therapy on the patients' immune system years after cancer-free survival remain poorly understood. Here, we present an in-depth characterization of the bone marrow immune ecosystem of multiple myeloma long-term survivors, from initial diagnosis up to 17 years following a single therapy line and cancer-free survival. Using comparative single-cell analyses combined with molecular, genomic, and functional approaches, we demonstrate that multiple myeloma long-term survivors exhibit pronounced alterations in their bone marrow microenvironment associated with impaired immunity. These immunological alterations were frequently linked to an inflammatory immune circuit fueled by the long-term persistence or resurgence of residual myeloma cells. Notably, even in the complete absence of any detectable residual disease for decades, sustained changes in the immune system were observed, suggesting an irreversible 'immunological scarring' caused by the initial exposure to the cancer and therapy. Collectively, our study provides key insights into the molecular and cellular bone marrow ecosystem of long-term survivors of multiple myeloma, revealing both reversible and irreversible alterations in the immune compartment.

The Prognostic Potential of circRNAs in Multiple Myeloma: Insights From Whole Bone Marrow and Purified Plasma Cells

Multiple myeloma (MM) is a haematological malignancy with abnormal proliferation of plasma cells in the bone marrow (BM), and MM patients with highly proliferative plasma cells have reduced overall survival. Circular RNAs (circRNAs) are endogenous, non-coding molecules that are promising biomarkers in cancer. Here, we present the largest study of circRNAs in MM to date and explore the prognostic potential of circRNAs and the link between proliferation and circRNA expression in MM. We performed deep total RNA sequencing (RNA-seq) on two cohorts: one cohort consisting of 45 whole BM MM patient samples and 13 healthy controls (HCs), and another cohort consisting of 43 CD138-purified plasma cell MM patient samples. We found that circRNAs are globally upregulated in the whole BM of MM patients compared to HCs. In whole BM, low proliferation and high circRNA levels were associated with a poor prognosis, while in purified plasma cells, low proliferation and high circRNA levels were associated with a favourable prognosis. Individual circRNAs from purified plasma cells were found to be significantly associated with MM patient outcomes and provide additional prognostic value to the proliferative indexes. Together, our findings emphasise the potential of circRNAs as prognostic biomarkers in MM.

Neuropsychiatric Adverse Events with Monoclonal Antibodies Approved for Multiple Myeloma: An Analysis from the FDA Adverse Event Reporting System

Background/Objectives: Monoclonal antibodies (mAbs) have revolutionized multiple myeloma (MM) treatment. However, post-marketing data on their neuropsychiatric safety are limited. This study aimed to evaluate neuropsychiatric adverse events (AEs) related to mAbs used for MM through a retrospective pharmacovigilance analysis using the Food and Drug Administration (FDA) Adverse Events Reporting System (FAERS) database. Methods: Individual case safety reports (ICSRs) from 2015 to 2023 with at least one neuropsychiatric AE and one of the MM-approved mAbs as the suspected drug (i.e., daratumumab, elotuzumab, isatuximab, belantamab mafodotin, teclistamab, elranatamab, and talquentamab) were analyzed using descriptive and disproportionality approaches. Results: Unknown signals of disproportionate reporting (SDR) included the following: cerebral infarction for daratumumab (n = 45; reporting odds ratio (ROR) = 2.39, 95% confidence interval (CI) = 1.79-3.21; information component (IC) = 1.54, IC025-IC075 = 1.05-1.9), elotuzumab (25; 7.61, 5.13-11.28; 3.03, 2.37-3.51), and isatuximab (10; 2.56, 1.38-4.76; 1.67, 0.59-2.4); mental status changes for daratumumab (40; 2.66, 1.95-3.63; 1.67, 1.14-2.04) and belantamab mafodotin (10; 4.23, 2.28-7.88; 2.3, 1.22-3.03); an altered state of consciousness for daratumumab (32; 1.97, 1.39-2.78; 1.32, 0.73-1.74) and belantamab mafodotin (6; 2.35, 1.05-5.23; 1.6, 0.19-2.52); Guillain-Barre syndrome (GBS) for daratumumab (23; 6.42, 4.26-9.69; 2.81, 2.11-3.3), isatuximab (8; 10.72, 5.35-21.48; 3.57, 2.35-4.37), and elotuzumab (3; 4.74, 1.53-14.7; 2.59, 0.52-3.8); and orthostatic intolerance for daratumumab (10; 12.54, 6.71-23.43; 3.75, 2.67-4.48) and elotuzumab (4; 28.31, 10.58-75.73; 5, 3.24-6.08). Conclusions: Our analysis highlighted several previously unacknowledged SDRs for MM-approved mAbs. Given the complex and not entirely understood etiology of some neuropsychiatric AEs, including GBS, further investigations are necessary.

A Ticking Time Bomb: A Case Report of Neutropenic Fever Secondary to Tick-Borne Illness

The advent of immunomodulatory therapies and their ever-expanding number of treatment indications necessitates the understanding of their associated complications. Neutropenic fever serves as an example of these complications often encountered in clinical practice. Although neutropenic fever can result from virtually any pathogen, episodes of the syndrome secondary to tick-borne illness remain relatively undocumented in the scientific literature. In the case presented, a 77-year-old female with a pertinent past medical history of smoldering IgG multiple myeloma on active immunosuppressive therapy presented with a first-time episode of neutropenic fever likely secondary to tick-borne illness. Through this report, attention is drawn to an additional source pathogen for neutropenic fever and its management, thus expanding upon clinician understanding of this all-too-common complication of immunosuppression.

Necrotizing Laryngitis in Patients with Hematologic Disease: The First Case-Report Due to PDR Acinetobacter baumannii and Literature Review

Immunocompromised patients with hematologic diseases may experience life-threatening infections with rather uncommon manifestations. Laryngitis has been described as a potential infection in such vulnerable patients and may result in major complications, ranging from impending airway obstruction to total laryngeal necrosis. Immediate laryngoscopy is of paramount importance, as it provides quantification of laryngeal edema and evidence of necrosis. Documentation of the causative pathogen is usually feasible through tissue culture. In the literature, 14 cases of necrotizing laryngitis have already been published. Here, we present the case of a 38-year-old male with a recent diagnosis of multiple myeloma, who received the first cycle of therapy a few days before admission. The patient presented with neutropenic fever, diarrhea, and multiple organ dysfunction. His course was complicated with hemophagocytic lymphohistiocytosis and stridor. A diagnosis of necrotizing laryngitis attributed to Acinetobacter baumannii invasion of the larynx was established. This manuscript highlights that the management of patients with hematologic disease and necrotizing laryngitis should be coordinated in highly specialized centers and clinicians should have a high level of clinical suspicion and act promptly.

Treg-derived TGF-β1 dampens cGAS-STING signaling to downregulate the expression of class I MHC complex in multiple myeloma

Multiple myeloma (MM) progression involves diminished tumor antigen presentation and an immunosuppressive microenvironment, characterized by diminished expression of major histocompatibility complexes (MHC) class I molecule and elevated programmed death ligand 1 (PDL1) in MM cells, along with an enriched population of regulatory T cells (Tregs). To investigate Treg's influence on MM cells, we established a co-culture system using Tregs from MM patients and the MM cell lines (MM.1S and SK-MM-1) in vitro and assessed the effects of intervening in the relevant pathways connecting Tregs and MM cells in vivo. In vitro, Tregs induced transforming growth factor beta-1 (TGF-β1) production, downregulated MHC I members, and increased PDL1 expression in MM cells. Treg-derived TGF-β1 suppressed the cGAS-STING pathway, contributing to the loss of MHC I molecule expression and PDL1 upregulation. Correspondingly, neutralizing TGF-β1 or activating the cGAS-STING pathway restored MHC I and PDL1 expression, effectively countering the pro-tumorigenic effect of Tregs on MM cells in vivo. These data elucidated how Tregs influence tumor antigen presentation and immunosuppressive signal in MM cells, potentially providing therapeutic strategies, such as neutralizing TGF-β1 or activating the cGAS-STING pathway, to address the immune escape and immunosuppressive dynamics in MM.

Tinostamustine (EDO-S101), an Alkylating Deacetylase Inhibitor, Enhances the Efficacy of Daratumumab in Multiple Myeloma by Upregulation of CD38 and NKG2D Ligands

Multiple myeloma is a malignancy characterized by the accumulation of malignant plasma cells in bone marrow and the production of monoclonal immunoglobulin. A hallmark of cancer is the evasion of immune surveillance. Histone deacetylase inhibitors have been shown to promote the expression of silenced molecules and hold potential to increase the anti-MM efficacy of immunotherapy. The aim of the present work was to assess the potential effect of tinostamustine (EDO-S101), a first-in-class alkylating deacetylase inhibitor, in combination with daratumumab, an anti-CD38 monoclonal antibody (mAb), through different preclinical studies. Tinostamustine increases CD38 expression in myeloma cell lines, an effect that occurs in parallel with an increment in CD38 histone H3 acetylation levels. Also, the expression of MICA and MICB, ligands for the NK cell activating receptor NKG2D, augments after tinostamustine treatment in myeloma cell lines and primary myeloma cells. Pretreatment of myeloma cell lines with tinostamustine increased the sensitivity of these cells to daratumumab through its different cytotoxic mechanisms, and the combination of these two drugs showed a higher anti-myeloma effect than individual treatments in ex vivo cultures of myeloma patients' samples. In vivo data confirmed that tinostamustine pretreatment followed by daratumumab administration significantly delayed tumor growth and improved the survival of mice compared to individual treatments. In summary, our results suggest that tinostamustine could be a potential candidate to improve the efficacy of anti-CD38 mAbs.

Targeted therapy for multiple myeloma: an overview on CD138-based strategies

Multiple myeloma (MM) is an incurable hematological disease characterized by the uncontrolled growth of plasma cells primarily in the bone marrow. Although its treatment consists of the administration of combined therapy regimens mainly based on immunomodulators and proteosome inhibitors, MM remains incurable, and most patients suffer from relapsed/refractory disease with poor prognosis and survival. The robust results achieved by immunotherapy targeting MM-associated antigens CD38 and CD319 (also known as SLAMF7) have drawn attention to the development of new immune-based strategies and different innovative compounds in the treatment of MM, including new monoclonal antibodies, antibody-drug conjugates, recombinant proteins, synthetic peptides, and adaptive cellular therapies. In this context, Syndecan1 (CD138 or SDC1), a transmembrane heparan sulfate proteoglycan that is upregulated in malignant plasma cells, has gained increasing attention in the panorama of MM target antigens, since its key role in MM tumorigenesis, progression and aggressiveness has been largely reported. Here, our aim is to provide an overview of the most important aspects of MM disease and to investigate the molecular functions of CD138 in physiologic and malignant cell states. In addition, we will shed light on the CD138-based therapeutic approaches currently being tested in preclinical and/or clinical phases in MM and discuss their properties, mechanisms of action and clinical applications.

CD200 genotype is associated with clinical outcome of patients with multiple myeloma

Immune dysfunction in patients with MM affects both the innate and adaptive immune system. Molecules involved in the immune response pathways are essential to determine the ability of cancer cells to escape from the immune system surveillance. However, few data are available concerning the role of immune checkpoint molecules in predicting the myeloma control and immunological scape as mechanism of disease progression. We retrospectively analyzed the clinical impact of the CD200 genotype (rs1131199 and rs2272022) in 291 patients with newly diagnosed MM. Patients with a CD200 rs1131199 GG genotype showed a median overall survival (OS) significantly lower than those with CC+CG genotype (67.8 months versus 94.4 months respectively; p: 0.022) maintaining significance in the multivariate analysis. This effect was specially detected in patients not receiving an autologous stem cell transplant (auto-SCT) (p < 0.001). In these patients the rs1131199 GG genotype negatively influenced in the mortality not related with the progression of MM (p: 0.02) mainly due to infections events.

CAR T-cell therapy in multiple myeloma: mission accomplished?

ABSTRACT

B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T cells are the most potent treatment against multiple myeloma (MM). Here, we review the increasing body of clinical and correlative preclinical data that support their inclusion into firstline therapy and sequencing before T-cell-engaging antibodies. The ambition to cure MM with (BCMA-)CAR T cells is informed by genomic and phenotypic analysis that assess BCMA expression for patient stratification and monitoring, steadily improving early diagnosis and management of side effects, and advances in rapid, scalable CAR T-cell manufacturing to improve access.

Multi-omics investigation of the resistance mechanisms of pomalidomide in multiple myeloma

Background

Despite significant therapeutic advances over the last decade, multiple myeloma remains an incurable disease. Pomalidomide is the third Immunomodulatory drug that is commonly used to treat patients with relapsed/refractory multiple myeloma. However, approximately half of the patients exhibit resistance to pomalidomide treatment. While previous studies have identified Cereblon as a primary target of Immunomodulatory drugs' anti-myeloma activity, it is crucial to explore additional mechanisms that are currently less understood.

Methods

To comprehensively investigate the mechanisms of drug resistance, we conducted integrated proteomic and metabonomic analyses of 12 plasma samples from multiple myeloma patients who had varying responses to pomalidomide. Differentially expressed proteins and metabolites were screened, and were further analyzed using pathway analysis and functional correlation analysis. Also, we estimated the cellular proportions based on ssGSEA algorithm. To investigate the potential role of glycine in modulating the response of MM cells to pomalidomide, cell viability and apoptosis were analyzed.

Results

Our findings revealed a consistent decrease in the levels of complement components in the pomalidomide-resistant group. Additionally, there were significant differences in the proportion of T follicular helper cell and B cells in the resistant group. Furthermore, glycine levels were significantly decreased in pomalidomide-resistant patients, and exogenous glycine administration increased the sensitivity of MM cell lines to pomalidomide.

Conclusion

These results demonstrate distinct molecular changes in the plasma of resistant patients that could be used as potential biomarkers for identifying resistance mechanisms for pomalidomide in multiple myeloma and developing immune-related therapeutic strategies.

Outcome of Second Primary Malignancies Developing in Multiple Myeloma Patients

BACKGROUND

There is an increased risk of second primary malignancies (SMPs) in patients with multiple myeloma (MM). This multinational 'real-world' retrospective study analyzed the characteristics and outcomes of MM patients that developed SPMs.

RESULTS

165 patients were analyzed: 62.4% males; 8.5% with a prior cancer; 113 with solid SPMs, mainly ≥stage 2; and 52 with hematological SPM (hemato-SPM), mainly MDS/AML. Patients with hemato-SPM were younger (p = 0.05) and more frequently had a prior AutoHCT (p = 0.012). The time to SPM was shorter in the older (>65 years) and more heavily pretreated patients. One hundred patients were actively treated at the time of SPM detection. Treatment was discontinued in 52, substituted with another anti-MM therapy in 15, and continued in 33 patients. Treatment discontinuation was predominant in the patients diagnosed with hemato-SPM (76%). The median OS following SPM detection was 8.5 months, and the main cause of death was SPM. A poor ECOG status predicted a shorter OS (PS 3 vs. 0, HR = 5.74, 2.32-14.21, p < 0.001), whereas a normal hemoglobin level (HR = 0.43, 0.19-0.95, p = 0.037) predicted longer OS.

CONCLUSIONS

With the continuing improvement in OS, a higher proportion of MM patients might develop SPM. The OS following SPM diagnosis is poor; hence, frequent surveillance and early detection are imperative to improve outcomes.

Mucosal-associated invariant T cells in hematological malignancies: Current knowledge, pending questions

Non-classical HLA restricted T cell subsets such as γδ T and NK-T cells are showing promises for immune-based therapy of hematological malignancies. Mucosal-Associated Invariant T cells (MAIT) belong to this family of innate-like T cell subsets and are the focus of many studies on infectious diseases, owing to their unusual recognition of bacterial/fungal metabolites. Their ability to produce type 1 cytokines (IFNγ, TNFα) as well as cytotoxic effector molecules endows them with potential anti-tumor functions. However, their contribution to tumor surveillance in solid cancers is unclear, and only few studies have specifically focused on MAIT cells in blood cancers. In this review, we wish to recapitulate our current knowledge on MAIT cells biology in hematological neoplasms, at diagnosis and/or during treatment, as well as tentative approaches to target them as therapeutic tools. We also wish to take this opportunity to briefly elaborate on what we think are important question to address in this field, as well as potential limitations to overcome in order to make MAIT cells the basis of future, novel therapies for hematological cancers.

Molecular Features of the Mesenchymal and Osteoblastic Cells in Multiple Myeloma

Multiple myeloma (MM) is a monoclonal gammopathy characterized by biological heterogeneity and unregulated proliferation of plasma cells (PCs) in bone marrow (BM). MM is a multistep process based on genomic instability, epigenetic dysregulation and a tight cross-talk with the BM microenvironment that plays a pivotal role supporting the proliferation, survival, drug-resistance and homing of PCs. The BM microenvironment consists of a hematopoietic and a non-hematopoietic compartment, which cooperate to create a tumor environment. Among the non-hematopoietic component, mesenchymal stromal cells (MSCs) and osteoblasts (OBs) appear transcriptionally and functionally different in MM patients compared to healthy donors (HDs) and to patients with pre-malignant monoclonal gammopathies. Alterations of both MSCs and OBs underly the osteolytic lesions that characterize myeloma-associated bone disease. In this review, we will discuss the different characteristics of MSCs and OBs in MM patients, analyzing the transcriptome, the deregulated molecular pathways and the role performed by miRNAs and exosome in the pathophysiology of MM.

The prognostic and therapeutic potentials of CTLA-4 in hematological malignancies

INTRODUCTION

Hematological Malignancies (HMs) are a group of progressive, difficult-to-treat, and highly recurrent diseases. A suppressed phenotype of the immune system is present in HMs and growing evidence indicates the role of Cytotoxic T lymphocyte-Associated protein 4 (CTLA-4) in the course of HMs.

AREAS COVERED

This article reviews the recent literature on the role of CTLA-4 in different subtypes of HMs. Here, the studies on the expression pattern, its effect on the prognosis of different HMs, and polymorphisms of CTLA-4 have been elaborated. Finally, the effect of targeting CTLA-4 in vitro and in vivo, as well as in clinical trials, is discussed.

EXPERT OPINION

According to the recent literature, CTLA-4 is overexpressed in different HMs, which is correlated with poor survival, while it is associated with better a prognosis in Chronic Lymphocytic Leukemia (CLL). Targeting CTLA-4 in Acute Myeloid Leukemia (AML), Sezary Syndrome (SS), Hodgkin's Lymphoma (HL), and so on, is helpful. While this is not recommended and may even be harmful in multiple myeloma (MM) and CLL. Also, it seems that certain CTLA-4 gene polymorphisms are efficient factors in the course of HMs. Future studies may broaden our knowledge regarding the role of CTLA-4 in HMs.

Bispecific Antibodies for the Treatment of Multiple Myeloma

PURPOSE OF REVIEW

Advances in multiple myeloma therapies have greatly improved outcomes for patients living with the disease, although to date there is yet to be a cure. Cellular and immunotherapies, approved or in development, offer the promise of significantly advancing toward that possibility. The aim of this review is to provide a synopsis and commentary on the current and future states of bispecific agents aimed at harnessing the antineoplastic potential of T-cells in treating and eradicating myeloma.

RECENT FINDINGS

Numerous bispecific agents are in clinical development with some on the precipice of regulatory approval. While BCMA remains the principal target, some agents are directed at novel targets such as GPRC5D and FcRH5. The constructs vary in design and pharmacokinetics which has dosing and administration implications. The toxicity profiles of these agents generally reflect that of other immune therapies, including cytokine release syndrome and rarely neurotoxicity, although immunosuppression has also led to elevated infection risks. However, the toxicities are generally manageable and offset by unprecedented efficacy seen in such heavily pretreated cohorts. Bispecific agents are poised to significantly alter the treatment paradigms for myeloma. They provide a convenient "off-the-shelf" platform with often deep and durable responses. Toxicities are often limited in duration and severity. In the early-phase trials, many patients have been able to remain on treatment for extended periods, even among those with high-risk features. Upcoming trials are likely to explore earlier implementation of these agents in order to offer this therapeutic opportunity to broader cohorts.

Contribution of the Tumor Microenvironment to Metabolic Changes Triggering Resistance of Multiple Myeloma to Proteasome Inhibitors

Virtually all patients with multiple myeloma become unresponsive to treatment with proteasome inhibitors over time. Relapsed/refractory multiple myeloma is accompanied by the clonal evolution of myeloma cells with heterogeneous genomic aberrations, diverse proteomic and metabolic alterations, and profound changes of the bone marrow microenvironment. However, the molecular mechanisms that drive resistance to proteasome inhibitors within the context of the bone marrow microenvironment remain elusive. In this review article, we summarize the latest knowledge about the complex interaction of malignant plasma cells with its surrounding microenvironment. We discuss the pivotal role of metabolic reprograming of malignant plasma cells within the tumor microenvironment with a subsequent focus on metabolic rewiring in plasma cells upon treatment with proteasome inhibitors, driving multiple ways of adaptation to the treatment. At the same time, mutual interaction of plasma cells with the surrounding tumor microenvironment drives multiple metabolic alterations in the bone marrow. This provides a tumor-promoting environment, but at the same time may offer novel therapeutic options for the treatment of relapsed/refractory myeloma patients.

Understanding the Bioactivity and Prognostic Implication of Commonly Used Surface Antigens in Multiple Myeloma

Multiple myeloma (MM) progression is dependent on its interaction with the bone marrow microenvironment and the immune system and is mediated by key surface antigens. Some antigens promote adhesion to the bone marrow matrix and stromal cells, while others are involved in intercellular interactions that result in differentiation of B-cells to plasma cells (PC). These interactions are also involved in malignant transformation of the normal PC to MM PC as well as disease progression. Here, we review selected surface antigens that are commonly used in the flow cytometry analysis of MM for identification of plasma cells (PC) and the discrimination between normal and malignant PC as well as prognostication. These include the markers: CD38, CD138, CD45, CD19, CD117, CD56, CD81, CD27, and CD28. Furthermore, we will discuss the novel marker CD24 and its involvement in MM. The bioactivity of each antigen is reviewed, as well as its expression on normal vs. malignant PC, prognostic implications, and therapeutic utility. Understanding the role of these specific surface antigens, as well as complex co-expressions of combinations of antigens, may allow for a more personalized prognostic monitoring and treatment of MM patients.

Engineered cancer cell membranes: An emerging agent for efficient cancer theranostics

For efficient cancer theranostics, surface modification of nanomaterials plays an important role in improving targeting ability and reducing the non-specific interactions with normal tissues. Recently, the biomimetic technology represented by coating of cancer cell membranes (CCMs) has been regarded as a promising method to strengthen the biocompatibility and targeting specificity of nanomaterials. Furthermore, the engineered CCMs (ECCMs) integrated with the natural biological properties of CCMs and specific functions from other cells or proteins have offered more possibilities in the field of cancer theranostics. Herein, the recent progresses in the design and preparation of ECCMs are summarized, and the applications of ECCMs in targeting delivery, activation of immunity, and detection of circulating tumor cells are reviewed. Finally, the current challenges and future perspectives with regard to the development of ECCMs are briefly discussed.

Harnessing the Immune System to Fight Multiple Myeloma

Multiple myeloma (MM) is a heterogeneous plasma cell malignancy differing substantially in clinical behavior, prognosis, and response to treatment. With the advent of novel therapies, many patients achieve long-lasting remissions, but some experience aggressive and treatment refractory relapses. So far, MM is considered incurable. Myeloma pathogenesis can broadly be explained by two interacting mechanisms, intraclonal evolution of cancer cells and development of an immunosuppressive tumor microenvironment. Failures in isotype class switching and somatic hypermutations result in the neoplastic transformation typical of MM and other B cell malignancies. Interestingly, although genetic alterations occur and evolve over time, they are also present in premalignant stages, which never progress to MM, suggesting that genetic mutations are necessary but not sufficient for myeloma transformation. Changes in composition and function of the immune cells are associated with loss of effective immune surveillance, which might represent another mechanism driving malignant transformation. During the last decade, the traditional view on myeloma treatment has changed dramatically. It is increasingly evident that treatment strategies solely based on targeting intrinsic properties of myeloma cells are insufficient. Lately, approaches that redirect the cells of the otherwise suppressed immune system to take control over myeloma have emerged. Evidence of utility of this principle was initially established by the observation of the graft-versus-myeloma effect in allogeneic stem cell-transplanted patients. A variety of new strategies to harness both innate and antigen-specific immunity against MM have recently been developed and intensively tested in clinical trials. This review aims to give readers a basic understanding of how the immune system can be engaged to treat MM, to summarize the main immunotherapeutic modalities, their current role in clinical care, and future prospects.

Deregulated Expression of Immune Checkpoints on Circulating CD4 T Cells May Complicate Clinical Outcome and Response to Treatment with Checkpoint Inhibitors in Multiple Myeloma Patients

Unlike solid-tumor patients, a disappointingly small subset of multiple myeloma (MM) patients treated with checkpoint inhibitors derive clinical benefits, suggesting differential participation of inhibitory receptors involved in the development of T-cell-mediated immunosuppression. In fact, T cells in MM patients have recently been shown to display features of immunosenescence and exhaustion involved in immune response inhibition. Therefore, we aimed to identify the dominant inhibitory pathway in MM patients to achieve its effective control by therapeutic interventions. By flow cytometry, we examined peripheral blood (PB) CD4 T cell characteristics assigned to senescence or exhaustion, considering PD-1, CTLA-4, and BTLA checkpoint expression, as well as secretory effector function, i.e., capacity for IFN-γ and IL-17 secretion. Analyses were performed in a total of 40 active myeloma patients (newly diagnosed and treated) and 20 healthy controls. At the single-cell level, we found a loss of studied checkpoints’ expression on MM CD4 T cells (both effector (Teff) and regulatory (Treg) cells) primarily at diagnosis; the checkpoint deficit in MM relapse was not significant. Nonetheless, PD-1 was the only checkpoint distributed on an increased proportion of T cells in all MM patients irrespective of disease phase, and its expression on CD4 Teff cells correlated with adverse clinical courses. Among patients, the relative defect in secretory effector function of CD4 T cells was more pronounced at myeloma relapse (as seen in declined Th1/Treg and Th17/Treg cell rates). Although the contribution of PD-1 to MM clinical outcomes is suggestive, our study clearly indicated that the inappropriate expression of immune checkpoints (associated with dysfunctionality of CD4 T cells and disease clinical phase) might be responsible for the sub-optimal clinical response to therapeutic checkpoint inhibitors in MM.

Mechanisms of Immune Evasion in Multiple Myeloma: Open Questions and Therapeutic Opportunities

Multiple myeloma (MM) is the second most common hematologic malignancy, characterized by a multi-step evolutionary path, which starts with an early asymptomatic stage, defined as monoclonal gammopathy of undetermined significance (MGUS) evolving to overt disease in 1% of cases per year, often through an intermediate phase known as "smoldering" MM (sMM). Interestingly, while many genomic alterations (translocation, deletions, mutations) are usually found at early stages, they are not sufficient (alone) to determine disease evolution. The latter, indeed, relies on significant "epigenetic" alterations of different normal cell populations within the bone marrow (BM) niche, including the "evasion" from immune-system control. Additionally, MM cells could "educate" the BM immune microenvironment (BM-IM) towards a pro-inflammatory and immunosuppressive phenotype, which ultimately leads to disease evolution, drug resistance, and patients' worse outcome. Indeed, it is not a case that the most important drugs for the treatment of MM include immunomodulatory agents (thalidomide, lenalidomide, and pomalidomide) and monoclonal antibodies (daratumumab, isatuximab, and elotuzumab). On these bases, in this review, we describe the most recent advances in the comprehension of the role of the different cells composing the BM-IM, and we discuss the potential molecular targets, which could represent new opportunities to improve current treatment strategies for MM patients.

Bone Marrow Mesenchymal Stromal Cells in Multiple Myeloma: Their Role as Active Contributors to Myeloma Progression

Multiple myeloma (MM) is a hematological malignancy of plasma cells that proliferate and accumulate within the bone marrow (BM). Work from many groups has made evident that the complex microenvironment of the BM plays a crucial role in myeloma progression and response to therapeutic agents. Within the cellular components of the BM, we will specifically focus on mesenchymal stromal cells (MSCs), which are known to interact with myeloma cells and the other components of the BM through cell to cell, soluble factors and, as more recently evidenced, through extracellular vesicles. Multiple structural and functional abnormalities have been found when characterizing MSCs derived from myeloma patients (MM-MSCs) and comparing them to those from healthy donors (HD-MSCs). Other studies have identified differences in genomic, mRNA, microRNA, histone modification, and DNA methylation profiles. We discuss these distinctive features shaping MM-MSCs and propose a model for the transition from HD-MSCs to MM-MSCs as a consequence of the interaction with myeloma cells. Finally, we review the contribution of MM-MSCs to several aspects of myeloma pathology, specifically to myeloma growth and survival, drug resistance, dissemination and homing, myeloma bone disease, and the induction of a pro-inflammatory and immunosuppressive microenvironment.

Targeting Reactive Oxygen Species Metabolism to Induce Myeloma Cell Death

Multiple myeloma (MM) is a common hematological disease characterized by the accumulation of clonal malignant plasma cells in the bone marrow. Over the past two decades, new therapeutic strategies have significantly improved the treatment outcome and patients survival. Nevertheless, most MM patients relapse underlying the need of new therapeutic approaches. Plasma cells are prone to produce large amounts of immunoglobulins causing the production of intracellular ROS. Although adapted to high level of ROS, MM cells die when exposed to drugs increasing ROS production either directly or by inhibiting antioxidant enzymes. In this review, we discuss the efficacy of ROS-generating drugs for inducing MM cell death and counteracting acquired drug resistance specifically toward proteasome inhibitors.