Immunotherapy based on bispecific T-cell engager with hIgG1 Fc sequence as a new therapeutic strategy in multiple myeloma

Bispecific antibodies in the treatment of multiple myeloma

The treatment paradigm in myeloma is constantly changing. Upfront use of monoclonal antibodies like daratumumab along with proteasome inhibitors (PI)s, and immune modulators (IMiD)s have significantly improved survival and outcomes, but also cause unique challenges at the time of relapse. Engaging immune T cells for tumour cell kill with chimeric antigenic T-cell (CAR T-cell) therapy and bispecific antibodies have become important therapeutic options in relapsed multiple myeloma. Bispecific antibodies are dual antigen targeting constructs that engage the T cells to plasma cells through various target antigens like B-cell membrane antigen (BCMA), G-protein-coupled receptor family C group 5 member D (GPRC5D), and Fc receptor-homolog 5 (FcRH5). These agents have proven to induce deep and durable responses in heavily pre-treated myeloma patients with a predictable safety profile and the ease of off-the-shelf availability. Significant research is ongoing to overcome resistance mechanisms like T cell exhaustion, target antigen mutation or loss and high disease burden. Various trials are also studying these agents as first line options in the newly diagnosed setting. These agents play an important role in the relapsed setting, and efforts are underway to optimize their sequencing in the myeloma treatment algorithm.

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.

The Role of Bispecific Antibodies in Relapsed Refractory Multiple Myeloma: A Systematic Review

Multiple myeloma is a heterogeneous clonal malignant plasma cell disorder, which remains incurable despite the therapeutic armamentarium's evolution. Bispecific antibodies (BsAbs) can bind simultaneously to the CD3 T-cell receptor and tumor antigen of myeloma cells, causing cell lysis. This systematic review of phase I/II/III clinical trials aimed to analyze the efficacy and safety of BsAbs in relapsed refractory multiple myeloma (RRMM). A thorough literature search was performed using PubMed, Cochrane Library, EMBASE, and major conference abstracts. A total of 18 phase I/II/III studies, including 1283 patients, met the inclusion criteria. Among the B-cell maturation antigen (BCMA)-targeting agents across 13 studies, the overall response rate (ORR) ranged between 25% and 100%, with complete response/stringent complete response (CR/sCR) between 7 and 38%, very good partial response (VGPR) between 5 and 92%, and partial response (PR) between 5 and 14%. Among the non-BCMA-targeting agents across five studies, the ORR ranged between 60 and 100%, with CR/sCR seen in 19-63%, and VGPR in 21-65%. The common adverse events were cytokine release syndrome (17-82%), anemia (5-52%), neutropenia (12-75%), and thrombocytopenia (14-42%). BsAbs have shown promising efficacy against RRMM cohorts with a good safety profile. Upcoming phase II/III trials are much awaited, along with the study of other agents in concert with BsAbs to gauge response.

Current Main Topics in Multiple Myeloma

Multiple Myeloma (MM) remains a difficult to treat disease mainly due to its biological heterogeneity, of which we are more and more knowledgeable thanks to the development of increasingly sensitive molecular methods that allow us to build better prognostication models. The biological diversity translates into a wide range of clinical outcomes from long-lasting remission in some patients to very early relapse in others. In NDMM transplant eligible (TE) patients, the incorporation of mAb as daratumumab in the induction regimens, followed by autologous stem cell transplantation (ASCT) and consolidation/maintenance therapy, has led to a significant improvement of PFS and OS.; however, this outcome remains poor in ultra-high risk MM or in those who did not achieve a minimal residual disease (MRD) negativity. Several trials are exploring cytogenetic risk-adapted and MRD-driven therapies in these patients. Similarly, quadruplets-containing daratumumab, particularly when administered as continuous therapies, have improved outcome of patients not eligible for autologous transplant (NTE). Patients who become refractory to conventional therapies have noticeably poor outcomes, making their treatment a difficult challenge in need of novel strategies. In this review, we will focus on the main points regarding risk stratification, treatment and monitoring of MM, highlighting the most recent evidence that could modify the management of this still incurable disease.

Bispecific T-cell engagers for treatment of multiple myeloma

Bispecific T cell engagers (TCE) derive from monoclonal antibodies and concomitantly engage a target on the surface of cancer cell and CD3 on the surface of T-cells. TCEs promote T cell activation and lysis of tumor cells. Most TCEs in development for multiple myeloma (MM) target the B cell maturation antigen (BCMA) and differ among themselves in structure, pharmacokinetics, route and schedule of administration. CD3/BCMA TCEs produce response in ~60% of patients treated in phase 1 trials. TCEs are also in development targeting the G protein-coupled receptor, class C group 5 member D (GPRC5D) and the Fc receptor homologue 5 (FcRH5). Main toxicities are cytokine release syndrome and cytopenias. Here we review the current development and future directions of TCEs in MM.

Bispecific antibodies in multiple myeloma treatment: A journey in progress

The incorporation of novel agents and monoclonal antibody-based therapies into the treatment of multiple myeloma (MM) has significantly improved long-term patient survival. However, the disease is still largely incurable, with high-risk patients suffering shorter survival times, partly due to weakened immune systems. Bispecific molecules, including bispecific antibodies (BisAbs) and bispecific T-cell engagers (BiTEs), encourage immune cells to lyse MM cells by simultaneously binding antigens on MM cells and immune effector cells, bringing those cells into close proximity. BisAbs that target B-cell maturation antigen (BCMA) and GPRC5D have shown impressive clinical activity, and the results of early-phase clinical trials targeting FcRH5 in patients with relapsed/refractory MM (RRMM) are also promising. Furthermore, the safety profile of these agents is favorable, including mainly low-grade cytokine release syndrome (CRS). These off-the-shelf bispecific molecules will likely become an essential part of the MM treatment paradigm. Here, we summarize and highlight various bispecific immunotherapies under development in MM treatment, as well as the utility of combining them with current standard-of-care treatments and new strategies. With the advancement of novel combination treatment approaches, these bispecific molecules may lead the way to a cure for MM.

Real-world utilisation of ASCT in multiple myeloma (MM): a report from the Australian and New Zealand myeloma and related diseases registry (MRDR)

Supported by clinical trial proven survival benefit, clinical guidelines recommend upfront autologous stem cell transplantation (ASCT) for eligible MM patients. However, reported real-world utilisation is lower than expected (40-60%). We reviewed ASCT utilisation, demographics and outcomes for MM patients (≤70 years, ≥12-month follow-up) enroled onto the Australian/New Zealand MRDR from June 2012 to May 2020. In 982 patients (<65 years: 684, 65-70 years: 298), ASCT utilisation was 76% overall (<65 years: 83%, 65-70 years: 61%, front-line therapy: 67%). Non-ASCT recipients were older (median age: 65 years vs 60 years, p < 0.001), had more comorbidities (cardiac disease: 16.9% vs 5.4%, p < 0.001; diabetes: 19.1% vs 7.0%, p < 0.001; renal dysfunction: median eGFR(ml/min): 68 vs 80, p < 0.001), inferior performance status (ECOG ≥ 2: 26% vs 13%, p < 0.001) and higher-risk MM (ISS-3: 37% vs 26%, p = 0.009, R-ISS-3 18.6% vs 11.8%, p = 0.051) than ASCT recipients. ASCT survival benefit (median progression-free survival (PFS): 45.3 months vs 35.2 months, p < 0.001; overall survival (OS): NR vs 64.0 months, p < 0.001) was maintained irrespective of age (<65 years: median PFS: 45.3 months vs 37.7 months, p = 0.04, OS: NR vs 68.2 months, p = 0.002; 65-70 years: median PFS: 46.7 months vs 29.2 months, p < 0.001, OS: 76.9 months vs 55.6 months, p = 0.005). This large, real-world cohort reaffirms ASCT survival benefit, including in 'older' patients necessitating well-designed studies evaluating ASCT in 'older' MM to inform evidence-based patient selection.

Multiple myeloma: therapeutic delivery of antibodies and aptamers

Multiple myeloma is the second most common hematological malignancy in adults, accounting for 2% of all cancer-related deaths in the UK. Current chemotherapy-based regimes are insufficient, as most patients relapse and develop therapy resistance. This review focuses on current novel antibody- and aptamer-based therapies aiming to overcome current therapy limitations, as well as their respective limitations and areas of improvement. The use of computer modeling methods, as a tool to study and improve ligand-receptor alignments for the use of novel therapy development will also be discussed, as it has become a rapid, reliable and comparatively inexpensive method of investigation.

Bispecific Antibodies in Multiple Myeloma: Present and Future

Despite many recent advances in therapy, there is still no plateau in overall survival curves in multiple myeloma. Bispecific antibodies are a novel immunotherapeutic approach designed to bind antigens on malignant plasma cells and cytotoxic immune effector cells. Early-phase clinical trials targeting B-cell maturation antigen (BCMA), GPRC5D, and FcRH5 have demonstrated a favorable safety profile, with mainly low-grade cytokine release syndrome, cytopenias, and infections. Although dose escalation is ongoing in several studies, early efficacy data show response rates in the most active dose cohorts between 61% and 83% with many deep responses; however, durability remains to be established. Further clinical trial data are eagerly anticipated.

SIGNIFICANCE

Overall survival of triple-class refractory multiple myeloma remains poor. Bispecific antibodies are a novel immunotherapeutic modality with a favorable safety profile and impressive preliminary efficacy in heavily treated patients. Although more data are needed, bispecifics will likely become an integral part of the multiple myeloma treatment paradigm in the near future. Studies in earlier lines of therapy and in combination with other active anti-multiple myeloma agents will help further define the role of bispecifics in multiple myeloma.

The evolving status of immunotherapies in multiple myeloma: the future role of bispecific antibodies

Treatment outcomes in multiple myeloma (MM) have improved dramatically over the past 10 years. However, patients with high-risk disease such as those with Stage III disease by the Revised International Staging System, the presence of adverse cytogenetics, or who are refractory to proteosome inhibitors, immunomodulatory drugs and monoclonal antibodies may have dismal outcomes. These patients represent an urgent ongoing need in MM. One of the hallmarks of MM is immune dysfunction and a tumour-permissive immune microenvironment. Ameliorating the immune-paresis could lead to improved outcomes. The role of immunotherapies has been growing at an exponential pace with numerous agents under development in clinical trials. In the present review, we provide an overview of immunotherapies in MM, focussing on bispecific antibodies (BsAbs). We review efficacy outcomes from the published clinical trials and consider the important safety aspects of these therapies, in particular the risk of cytokine-release syndrome and immune effector cell-associated neurotoxicity syndrome, and how these compare with patients receiving chimeric antigen receptor T cells. We discuss the MM epitopes being targeted by BsAbs, either in clinical or preclinical stages, and we consider where these therapies might best fit within the future ever-changing paradigm of MM treatment.

Bispecific T Cell Engagers for the Treatment of Multiple Myeloma: Achievements and Challenges

MM is the second most common hematological malignancy and represents approximately 20% of deaths from hematopoietic cancers. The advent of novel agents has changed the therapeutic landscape of MM treatment; however, MM remains incurable. T cell-based immunotherapy such as BTCEs is a promising modality for the treatment of MM. This review article discusses the advancements and future directions of BTCE treatments for MM.

Any closer to successful therapy of multiple myeloma? CAR-T cell is a good reason for optimism

Despite many recent advances on cancer novel therapies, researchers have yet a long way to cure cancer. They have to deal with tough challenges before they can reach success. Nonetheless, it seems that recently developed immunotherapy-based therapy approaches such as adoptive cell transfer (ACT) have emerged as a promising therapeutic strategy against various kinds of tumors even the cancers in the blood (liquid cancers). The hematological (liquid) cancers are hard to be targeted by usual cancer therapies, for they do not form localized solid tumors. Until recently, two types of ACTs have been developed and introduced; tumor-infiltrating lymphocytes (TILs) and chimeric antigen receptor (CAR)-T cells which the latter is the subject of our discussion. It is interesting about engineered CAR-T cells that they are genetically endowed with unique cancer-specific characteristics, so they can use the potency of the host immune system to fight against either solid or liquid cancers. Multiple myeloma (MM) or simply referred to as myeloma is a type of hematological malignancy that affects the plasma cells. The cancerous plasma cells produce immunoglobulins (antibodies) uncontrollably which consequently damage the tissues and organs and break the immune system function. Although the last few years have seen significant progressions in the treatment of MM, still a complete remission remains unconvincing. MM is a medically challenging and stubborn disease with a disappointingly low rate of survival rate. When comparing the three most occurring blood cancers (i.e., lymphoma, leukemia, and myeloma), myeloma has the lowest 5-year survival rate (around 40%). A low survival rate indicates a high mortality rate with difficulty in treatment. Therefore, novel CAR-T cell-based therapies or combination therapies along with CAT-T cells may bring new hope for multiple myeloma patients. CAR-T cell therapy has a high potential to improve the remission success rate in patients with MM. To date, many preclinical and clinical trial studies have been conducted to investigate the ability and capacity of CAR T cells in targeting the antigens on myeloma cells. Despite the problems and obstacles, CAR-T cell experiments in MM patients revealed a robust therapeutic potential. However, several factors might be considered during CAR-T cell therapy for better response and reduced side effects. Also, incorporating the CAT-T cell method into a combinational treatment schedule may be a promising approach. In this paper, with a greater emphasis on CAR-T cell application in the treatment of MM, we will discuss and introduce CAR-T cell's history and functions, their limitations, and the solutions to defeat the limitations and different types of modifications on CAR-T cells.

The Myeloma Landscape in Australia and New Zealand: The First 8 Years of the Myeloma and Related Diseases Registry (MRDR)

BACKGROUND

Real-world multiple myeloma (MM) data are scarce, with most data originating from clinical trials. The Myeloma and Related Diseases Registry (MRDR) is a prospective clinical-quality registry of newly diagnosed cases of plasma cell disorders established in 2012 and operating at 44 sites in Australia and New Zealand as of April 2020.

METHODS

We reviewed all patients enrolled onto the MRDR between June 2012 and April 2020. Baseline characteristics, treatment, and outcome data were reviewed for MM patients with comparisons made by chi-square tests (categorical variables) and rank sum tests (continuous variables). Kaplan-Meier analysis was used to estimate progression-free survival and overall survival (OS).

RESULTS

As of April 2020, a total of 2405 MM patients were enrolled (median age, 67 years, with 40% aged > 70 years). High-risk features were present in 13% to 31% of patients: fluorescence in-situ hybridization (FISH) ≥ 1 of t(4;14), t(14;16), or del(17p) 18%, International Staging System (ISS)-3 31%, and Revised ISS (R-ISS)-3 13%. Cytogenetic/FISH analyses were performed in 50% and 68% of patients, respectively, with an abnormal karyotype result in 34%. Bortezomib-containing therapy was the most common first-line therapy (79.3%, n = 1706). Patients not receiving bortezomib were older (median age, 76 vs 65 years, P < .001) with inferior performance status (Eastern Cooperative Oncology Group performance status ≥ 2, 41% vs 18%, P < .001). Median progression-free survival and OS were 30.8 and 65.8 months, respectively. Younger patients had superior OS (76.3 vs 46.7 months, P < .001, < 70 and ≥ 70 years, respectively). R-ISS score was available in 50.7% (n = 1220) of patients, and higher R-ISS was associated with inferior OS (R-ISS-1 vs R-ISS-2 vs R-ISS-3: not reached vs 68.1 months vs 33.2 months, respectively, P < .001).

CONCLUSION

Clinical registries provide a more complete picture of MM diagnosis and treatment, and highlight the challenges of adhering to best practices in a real-world context.

Harnessing the Immune System Against Multiple Myeloma: Challenges and Opportunities

Multiple myeloma (MM) is an incurable malignancy of plasma cells that grow within a permissive bone marrow microenvironment (BMM). The bone marrow milieu supports the malignant transformation both by promoting uncontrolled proliferation and resistance to cell death in MM cells, and by hampering the immune response against the tumor clone. Hence, it is expected that restoring host anti-MM immunity may provide therapeutic benefit for MM patients. Already several immunotherapeutic approaches have shown promising results in the clinical setting. In this review, we outline recent findings demonstrating the potential advantages of targeting the immunosuppressive bone marrow niche to restore effective anti-MM immunity. We discuss different approaches aiming to boost the effector function of T cells and/or exploit innate or adaptive immunity, and highlight novel therapeutic opportunities to increase the immunogenicity of the MM clone. We also discuss the main challenges that hamper the efficacy of immune-based approaches, including intrinsic resistance of MM cells to activated immune-effectors, as well as the protective role of the immune-suppressive and inflammatory bone marrow milieu. Targeting mechanisms to convert the immunologically “cold” to “hot” MM BMM may induce durable immune responses, which in turn may result in long-lasting clinical benefit, even in patient subgroups with high-risk features and poor survival.

Belantamab Mafodotin to Treat Multiple Myeloma: A Comprehensive Review of Disease, Drug Efficacy and Side Effects

Multiple myeloma (MM) is a hematologic malignancy characterized by excessive clonal proliferation of plasma cells. The treatment of multiple myeloma presents a variety of unique challenges due to the complex molecular pathophysiology and incurable status of the disease at this time. Given that MM is the second most common blood cancer with a characteristic and unavoidable relapse/refractory state during the course of the disease, the development of new therapeutic modalities is crucial. Belantamab mafodotin (belamaf, GSK2857916) is a first-in-class therapeutic, indicated for patients who have previously attempted four other treatments, including an anti-CD38 monoclonal antibody, a proteosome inhibitor, and an immunomodulatory agent. In November 2017, the FDA designated belamaf as a breakthrough therapy for heavily pretreated patients with relapsed/refractory multiple myeloma. In August 2020, the FDA granted accelerated approval as a monotherapy for relapsed or treatment-refractory multiple myeloma. The drug was also approved in the EU for this indication in late August 2020. Of note, belamaf is associated with the following adverse events: decreased platelets, corneal disease, decreased or blurred vision, anemia, infusion-related reactions, pyrexia, and fetal risk, among others. Further studies are necessary to evaluate efficacy in comparison to other standard treatment modalities and as future drugs in this class are developed.

Bispecific Antibodies: A New Era of Treatment for Multiple Myeloma

Despite the introduction of novel agents such as proteasome inhibitors, immunomodulatory drugs, and autologous stem cell transplant, multiple myeloma (MM) largely remains an incurable disease. In recent years, monoclonal antibody-based treatment strategies have been developed to target specific surface antigens on MM cells. Treatment with bispecific antibodies (bsAbs) is an immunotherapeutic strategy that leads to an enhanced interaction between MM cells and immune effector cells, e.g., T-cells and natural killer cells. With the immune synapse built by bsAbs, the elimination of MM cells can be facilitated. To date, bsAbs have demonstrated encouraging results in preclinical studies, and clinical trials evaluating bsAbs in patients with MM are ongoing. Early clinical data show the promising efficacy of bsAbs in relapsed/refractory MM. Together with chimeric antigen receptor-modified (CAR)-T-cells, bsAbs represent a new dimension of precision medicine. In this review, we provide an overview of rationale, current clinical development, resistance mechanisms, and future directions of bsAbs in MM.

The Society for Immunotherapy of Cancer consensus statement on immunotherapy for the treatment of multiple myeloma

Outcomes in multiple myeloma (MM) have improved dramatically in the last two decades with the advent of novel therapies including immunomodulatory agents (IMiDs), proteasome inhibitors and monoclonal antibodies. In recent years, immunotherapy for the treatment of MM has advanced rapidly, with the approval of new targeted agents and monoclonal antibodies directed against myeloma cell-surface antigens, as well as maturing data from late stage trials of chimeric antigen receptor CAR T cells. Therapies that engage the immune system to treat myeloma offer significant clinical benefits with durable responses and manageable toxicity profiles, however, the appropriate use of these immunotherapy agents can present unique challenges for practicing physicians. Therefore, the Society for Immunotherapy of Cancer convened an expert panel, which met to consider the current role of approved and emerging immunotherapy agents in MM and provide guidance to the oncology community by developing consensus recommendations. As immunotherapy evolves as a therapeutic option for the treatment of MM, these guidelines will be updated.

Role of the Bone Marrow Milieu in Multiple Myeloma Progression and Therapeutic Resistance

Multiple myeloma (MM) is a cancer of the plasma cells within the bone marrow (BM). Studies have shown that the cellular and noncellular components of the BM milieu, such as cytokines and exosomes, play an integral role in MM pathogenesis and progression by mediating drug resistance and inducing MM proliferation. Moreover, the BM microenvironment of patients with MM facilitates cancer tolerance and immune evasion through the expansion of regulatory immune cells, inhibition of antitumor effector cells, and disruption of the antigen presentation machinery. These are of special relevance, especially in the current era of cancer immunotherapy. An improved understanding of the supportive role of the MM BM microenvironment will allow for the development of future therapies targeting MM in the context of the BM milieu to elicit deeper and more durable responses. In the present review, we have discussed our current understanding of the role of the BM microenvironment in MM progression and resistance to therapy and discuss novel potential approaches to alter its pro-MM function.

The Role of Immunotherapy in Non-transplant Eligible Multiple Myeloma

As the global population is aging and survival in multiple myeloma (MM) is increasing, treating older MM patients, redefined as non-transplant eligible (NTE), is becoming more frequent. Yet, treating these patients remains a real challenge especially because of a marked heterogeneity in the population and an increased susceptibility to treatment toxicity. Indeed, the balance between efficacy and safety must be considered at all time throughout the treatment history for these patients. Therefore, younger and older patients were historically treated in a very different way, even though the safety profile of most anti-myeloma drugs has drastically improved over the years. The emergence of immunotherapy (IT) has largely widened the therapeutic options available in MM and above all has allowed a therapy at optimal dose, and therefore optimal activity, for all patients independently of their frailty features, with no increase in safety issues. Among the novel anti-myeloma IT-based agents, anti-CD38 monoclonal antibodies (mAbs) are now becoming the new backbone of treatment for NTE patients, in association with lenalidomide and dexamethasone. Moreover, several new IT-based drugs are currently being developed and investigated either alone or in association; such as new anti-CD38 mAbs, anti-CD38 mAbs with many different combinations, but also the CAR-T cells, bispecific T-cell engager (BiTEs), or antibody drug conjugate (ADC) targeting BCMA. One would expect that immunotherapy will ultimately change and even transform the MM landscape, even for elderly patients. Immunotherapy represents a shift in treatment paradigm in MM as it provides truly efficient drugs with a very favorable safety profile.

Bispecific Antibodies for Multiple Myeloma: A Review of Targets, Drugs, Clinical Trials, and Future Directions

Multiple myeloma (MM) is a plasma cell malignancy and the second most common hematological neoplasm in adults, comprising 1.8% of all cancers. With an annual incidence of ~30,770 cases in the United States, MM has a high mortality rate, leading to 12,770 deaths per year. MM is a genetically complex, highly heterogeneous malignancy, with significant inter- and intra-patient clonal variability. Recent years have witnessed dramatic improvements in the diagnostics, classification, and treatment of MM. However, patients with high-risk disease have not yet benefited from therapeutic advances. High-risk patients are often primary refractory to treatment or relapse early, ultimately resulting in progression toward aggressive end-stage MM, with associated extramedullary disease or plasma cell leukemia. Therefore, novel treatment modalities are needed to improve the outcomes of these patients. Bispecific antibodies (BsAbs) are immunotherapeutics that simultaneously target and thereby redirect effector immune cells to tumor cells. BsAbs have shown high efficacy in B cell malignancies, including refractory/relapsed acute lymphoblastic leukemia. Various BsAbs targeting MM-specific antigens such as B cell maturation antigen (BCMA), CD38, and CD138 are currently in pre-clinical and clinical development, with promising results. In this review, we outline these advances, focusing on BsAb drugs, their targets, and their potential to improve survival, especially for high-risk MM patients. In combination with current treatment strategies, BsAbs may pave the way toward a cure for MM.

Monoclonal antibodies in multiple myeloma: Current and emerging targets and mechanisms of action

The recent development of monoclonal antibodies (mAbs) has revolutionized the treatment armamentarium for multiple myeloma. The success of daratumumab and elotuzumab in relapsed/refractory patients, has generated tremendous enthusiasm for mAbs in this disease. Combination treatment with other anti-myeloma treatment modalities and clinical evaluation in newly diagnosed patients are expected to fundamentally change the natural history of the disease. Advances in biopharmaceutical engineering together with a robust interest in novel mAb-derivatives, including antibody drug conjugates and poly-specific antibodies are the next rapidly approaching treatment frontier in multiple myeloma. In this review, we comprehensively outline the currently available evidence and the future landscape of mAbs and mAb-derivative therapies in multiple myeloma.

Role of cell surface proteoglycans in cancer immunotherapy

Over the past few decades, understanding how tumor cells evade the immune system and their communication with their tumor microenvironment, has been the subject of intense investigation, with the aim of developing new cancer immunotherapies. The current therapies against cancer such as monoclonal antibodies against checkpoint inhibitors, adoptive T-cell transfer, cytokines, vaccines, and oncolytic viruses have managed to improve the clinical outcome of the patients. However, in some tumor entities, the response is limited and could benefit from the identification of novel therapeutic targets. It is known that tumor-extracellular matrix interplay and matrix remodeling are necessary for anti-tumor and pro-tumoral immune responses. Proteoglycans are dominant components of the extracellular matrix and are a highly heterogeneous group of proteins characterized by the covalent attachment of a specific linear carbohydrate chain of the glycosaminoglycan type. At cell surfaces, these molecules modulate the expression and activity of cytokines, chemokines, growth factors, adhesion molecules, and function as signaling co-receptors. By these mechanisms, proteoglycans influence the behavior of cancer cells and their microenvironment during the progression of solid tumors and hematopoietic malignancies. In this review, we discuss why cell surface proteoglycans are attractive pharmacological targets in cancer, and we present current and recent developments in cancer immunology and immunotherapy utilizing proteoglycan-targeted strategies.

Investigational Monoclonal Antibodies in the Treatment of Multiple Myeloma: A Systematic Review of Agents under Clinical Development

BACKGROUND

Immunotherapy for multiple myeloma (MM) has been the focus in recent years due to its myeloma-specific immune responses. We reviewed the literature on non-Food and Drug Administration (FDA) approved monoclonal antibodies (mAbs) to highlight future perspectives. We searched PubMed, EMBASE, Web of Science, Cochrane Library and ClinicalTrials.gov to include phase I/II clinical trials. Data from 39 studies (1906 patients) were included. Of all the agents, Isatuximab (Isa, anti-CD38) and F50067 (anti-CXCR4) were the only mAbs to produce encouraging results as monotherapy with overall response rates (ORRs) of 66.7% and 32% respectively. Isa showed activity when used in combination with lenalidomide (Len) and dexamethasone (Dex), producing a clinical benefit rate (CBR) of 83%. Additionally, Isa used in combination with pomalidomide (Pom) and Dex resulted in a CBR of 73%. Indatuximab Ravtansine (anti-CD138 antibody-drug conjugate) produced an ORR of 78% and 79% when used in combination with Len-Dex and Pom-Dex, respectively.

CONCLUSIONS

Combination therapy using mAbs such as indatuximab, pembrolizumab, lorvotuzumab, siltuximab or dacetuzumab with chemotherapy agents produced better outcomes as compared to monotherapies. Further clinical trials investigating mAbs targeting CD38 used in combination therapy are warranted.

Immunotherapy in myeloma: how far have we come?

The treatment of multiple myeloma (MM) has evolved substantially over the past decades, leading to a significantly improved outcome of MM patients. The introduction of high-dose therapy, especially, and autologous stem cell transplantation, as well as the development of new drugs, such as immunomodulatory drugs (IMiDs) and proteasome inhibitors have contributed to the improvement in survival. However, eventually most MM patients relapse, which indicates that there is a need for new agents and novel treatment strategies. Importantly, the long-term survival in a subset of MM patients after allogeneic stem cell transplantation illustrates the potential of immunotherapy in MM, but allogeneic stem cell transplantation is also associated with a high rate of treatment-related mortality. Recently, a better insight into several immune-evasion mechanisms, which contribute to tumor progression, has resulted in the development of active and well-tolerated novel forms of immunotherapy. These immunotherapeutic agents can be used as monotherapy, or, even more successfully, in combination with other established anti-MM agents to further improve depth and duration of response by preventing the outgrowth of resistant clones. This review will discuss the mechanisms used by MM cells to evade the immune system, and also provide an overview of currently approved immunotherapeutic drugs, such as IMiDs (e.g. lenalidomide and pomalidomide) and monoclonal antibodies that target cell surface antigens present on the MM cell (e.g. elotuzumab and daratumumab), as well as novel immunotherapies (e.g. chimeric antigen receptor T-cells, bispecific antibodies and checkpoint inhibitors) currently in clinical development in MM.

Monoclonal Antibodies for the Treatment of Multiple Myeloma: An Update

The past two decades have seen a revolution in multiple myeloma (MM) therapy with the introduction of several small molecules, mostly orally effective, whose mechanisms are based on proteasome inhibition, histone deacetylase (HDAC) blockade, and immunomodulation. Immunotherapeutic approaches to MM treatment using monoclonal antibodies (mAbs), while long in development, began to reap success with the identification of CD38 and SLAMF7 as suitable targets for development, culminating in the 2015 Food and Drug Administration (FDA) approval of daratumumab and elotuzumab, respectively. This review highlights additional mAbs now in the developmental pipeline. Isatuximab, another anti-CD38 mAb, currently is under study in four phase III trials and may offer certain advantages over daratumumab. Several antibody-drug conjugates (ADCs) in the early stages of development are described, including JNJ-63723283, which has attained FDA breakthrough status for MM. Other mAbs described in this review include denosumab, recently approved for myeloma-associated bone loss, and checkpoint inhibitors, although the future status of the latter combined with immunomodulators has been clouded by unacceptably high death rates that caused the FDA to issue clinical holds on several of these trials. Also highlighted are the therapies based on the B Cell Maturation Antigen (BCMA), another very promising target for anti-myeloma development.

Immunotherapy: A Novel Era of Promising Treatments for Multiple Myeloma

Multiple myeloma (MM) remains an incurable hematological malignancy characterized by clonal proliferation of malignant plasma cells in bone marrow. In the last 20 years, the introduction of autologous stem cell transplantation, followed by proteasome inhibitors and immunomodulatory agents, increased the survival of MM patients by 50%. However, still a high proportion of patients relapse and become refractory, especially, high-risk patients with adverse cytogenetics where these treatment combinations have shown limited benefit. Therefore, novel strategies, such as immunotherapy, have been developed in the last few years to help improve the survival of these patients. Immunotherapy treatments include a high number of different strategies used to attack the tumor cells by using the immune system. Here, we will review the most successful immunotherapy strategies published up to date in patients with relapsed or refractory (R/R) MM, including monoclonal antibodies targeting specific antigens on the tumor cells, antibodies combined with cytotoxic drugs or Antibodies Drug Conjugates, immune checkpoint inhibitors which eliminate the barriers that damper immune cells and prevent them from attacking tumor cells, bi-specific T-cell engagers antibodies (BiTEs), bi-specific antibodies and the infusion of chimeric antigen receptor-modified T cells. We overview the results of clinical studies that have been presented up to date and also review pre-clinical studies describing potential novel treatments for MM.

T cell engaging bispecific antibody (T-BsAb): From technology to therapeutics

Harnessing the power of the human immune system to treat cancer is the essence of immunotherapy. Monoclonal antibodies engage the innate immune system to destroy targeted cells. For the last 30years, antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity have been the main mechanisms of anti-tumor action of unconjugated antibody drugs. Efforts to exploit the potentials of other immune cells, in particular T cells, culminated in the recent approval of two T cell engaging bispecific antibody (T-BsAb) drugs, thereby stimulating new efforts to accelerate similar platforms through preclinical and clinical trials. In this review, we have compiled the worldwide effort in exploring T cell engaging bispecific antibodies. Our special emphasis is on the lessons learned, with the hope to derive insights in this fast evolving field with tremendous clinical potential.

Redirecting T cells to hematological malignancies with bispecific antibodies

There is a need to improve outcomes for patients with recurrent and/or refractory hematological malignancies. Immunotherapy holds the promise to meet this need, because it does not rely on the cytotoxic mechanism of conventional therapies. Among different forms of immunotherapy, redirecting T cells to hematological malignancies with bispecific antibodies (BsAbs) is an attractive strategy. BsAbs are an "off-the-shelf" product that is easily scalable in contrast to adoptive T-cell therapies. Among these, the bispecific T-cell engager blinatumomab has emerged as the most successful BsAb to date. It consists of 2 single-chain variable fragments specific for CD19 present on B-cell malignancies and CD3 expressed on almost all T cells. Blinatumomab has shown potent antitumor activity as a single agent, particularly for acute lymphoblastic leukemia, resulting in its US Food and Drug Administration approval. However, although successful in inducing remissions, these are normally short-lived, with median response durations of <1 year. Nevertheless, the success of blinatumomab has reinvigorated the BsAb field, which is bustling with preclinical and clinical studies for not only B-cell-derived lymphoblastic leukemia and lymphoma but also acute myeloid leukemia and multiple myeloma. Here, we will review the successes and challenges of T-cell-targeted BsAbs for the immunotherapy of hematological malignancies with special focus on conducted clinical studies and strategies to improve their efficacy.

Monoclonal Antibodies in Multiple Myeloma: A New Wave of the Future

In 2015, 2 monoclonal antibodies were approved for the treatment of relapsed or refractory multiple myeloma (RRMM), elotuzumab and daratumumab. Elotuzumab is a monoclonal IgG-κ antibody directed against SLAMF7 (signaling lymphocytic activation molecule F7), a cell surface receptor involved in natural killer cell activation. Daratumumab is a monoclonal IgG-κ antibody that binds to CD38, a transmembrane protein found on the surface of myeloma cells and responsible for cellular adhesion and ectoenzymatic activity. Both elotuzumab and daratumumab act through recruitment of the immune system to enhance cellular cytotoxicity directed against myeloma cells. Elotuzumab requires lenalidomide and dexamethasone combined to enhance progression-free survival in patients with RRMM, and daratumumab has both single-agent and combination activity with either lenalidomide or the proteasome inhibitor bortezomib in RRMM. The adverse effect profile of both agents mainly consists of allergic-type infusion reactions. Other considerations for monoclonal antibody use in the treatment of MM include the potential for interference in serum protein electrophoresis testing and cross-reactivity of daratumumab with CD38 present on red blood cells. In the present report, we discussed the clinical development of daratumumab and elotuzumab and newer immunologic approaches to the treatment of MM.

Immunologic approaches for the treatment of multiple myeloma

The FDA approval of two monoclonal antibodies in 2015has heralded a new era of targeted immunotherapies for multiple myeloma (MM). In this review we discuss the recent approaches using different immunological components to treat MM. In particular, we review current monoclonal antibody based therapies, engineered T- and NK cell products, 'off-target' immunomodulation, and strategies utilizing allogeneic cell transplantation in MM. We discuss how an immunologic approach offers promise for the treatment of this genetically heterogeneous disease, and how patients with acquired drug resistance may particularly benefit from these therapies. We also describe some of the limitations of the current strategies and speculate on the future of personalized immunotherapies for MM.

Monoclonal antibody therapy in multiple myeloma

The therapeutic landscape of multiple myeloma (MM) has evolved spectacularly over the past decade with the discovery and validation of proteasome inhibitors and immunomodulatory agents as highly active agents, both in front-line therapy as well as in the relapse and maintenance settings. Although previous attempts to apply available monoclonal antibodies (Mabs) to the treatment of patients with MM has until recently been disappointing, novel targets specifically explored in the context of MM have recently lead to the first approvals of Mabs for the treatment of patients with MM. We have performed a literature search to identify preclinical targeting of MM, including in vitro and in vivo models using monoclonal antibodies, as well as clinical trials of monoclonal antibodies in patients with MM. Sources used were peer-reviewed publications, congress abstracts and on-line clinical trials data (such as clinicaltrials.gov). Several targets have been evaluated in preclinical models and a growing number of agents are being evaluated in clinical trials, as single agents or in combination and under various antibody formats. Two agents, targeting for the first time CD38 and SLAMF7, respectively, have recently been approved for the treatment of patients with MM. The recent approval of these two antibodies is expected to have a strong impact on treatment modalities and outcome in patients with MM, including both transplant eligible and elderly patients.

Carfilzomib boosted combination therapy for relapsed multiple myeloma

Carfilzomib is a proteasome inhibitor that binds selectively and irreversibly to the 20S proteasome, the proteolytic core particle within the 26S proteasome, resulting in the accumulation of proteasome substrates and ultimately growth arrest and apoptosis of tumor cells. The development and ultimate approval of this medication by regulatory agencies has been an important step toward improving clinical outcomes in multiple myeloma. Although initially approved as a single agent for the treatment of multiply relapsed and/or refractory myeloma, in the USA, it is now widely used in the early relapse setting in combination with lenalidomide and dexamethasone. Carfilzomib has also been studied in combination with second-generation immunomodulatory drugs, histone deacetylase inhibitors, alkylating agents and other novel medications. In this review article, we will discuss the efficacy, safety, tolerability and quality of life of carfilzomib-based combination therapies, as well as novel agents, for relapsed multiple myeloma.

Immunotherapy for the treatment of multiple myeloma

Immunotherapy has recently emerged as a promising treatment for multiple myeloma (MM). There are now several monoclonal antibodies that target specific surface antigens on myeloma cells or the checkpoints of immune and myeloma cells. Elotuzumab (targeting SLAMF7), daratumumab (targeting CD38), and pembrolizumab (targeting PD-1) have shown clinical activity in clinical studies with relapsed/refractory MM. Dendritic cell vaccination is a safe strategy that has shown some efficacy in a subset of myeloma patients and may become a crucial part of MM treatment when combined with immunomodulatory drugs or immune check-point blockade. Genetically engineered T cells, such as chimeric antigen receptor T cells or T cell receptor-engineered T cells, have also shown encouraging results in recent clinical studies of patients with MM. In this paper, we discuss recent progress in immunotherapy for the treatment of MM.

Role of Immunotherapy in Targeting the Bone Marrow Microenvironment in Multiple Myeloma: An Evolving Therapeutic Strategy

Multiple myeloma (referred to henceforth as myeloma) is a B-cell malignancy characterized by unregulated growth of plasma cells in the bone marrow. The treatment paradigm for myeloma underwent significant evolution in the last decade, with an improved understanding of the pathogenesis of the disease as well as the development of therapeutic agents that target not only the tumor cells but also their microenvironment. Despite these therapeutic advances, the prognosis of patients with relapsed or refractory myeloma remains poor. Accordingly, a need exists for new therapeutic avenues that can overcome resistance to current therapies and improve survival outcomes. In addition, myeloma is associated with progressive immune dysregulation, with defects in T-cell immunity, natural killer cell function, and the antigen-presenting capacity of dendritic cells, resulting in a tumor microenvironment that promotes disease tolerance and progression. Together, the immunosuppressive microenvironment and oncogenic mutations activate signaling networks that promote myeloma cell survival. Immunotherapy incorporates novel treatment options (e.g., monoclonal antibodies, antibody-drug conjugates, chimeric antigen receptor T-cell therapy, immune checkpoint inhibitors, bispecific antibodies, and tumor vaccines) either alone or in combination with existing lines of therapies (e.g., immunomodulatory agents, proteasome inhibitors, and histone deacetylase inhibitors) to enhance the host anti myeloma immunity within the bone marrow microenvironment and improve clinical response. Following the U.S. Food and Drug Administration approval of daratumumab and elotuzumab in 2015, more immunotherapeutic agents are expected to be become available as valuable treatment options in the near future. This review provides a basic understanding of the role of immunotherapy in modulating the bone marrow tumor microenvironment and its role in the treatment of myeloma. Clinical efficacy and safety of recently approved therapeutic monoclonal antibodies (daratumumab, elotuzumab) are discussed, along with the therapeutic potential of emerging immunotherapies (antibody-drug conjugates, chimeric antigen receptor T-cell therapy, tumor vaccines, and immune checkpoint inhibitors).

Designing multivalent proteins based on natural killer cell receptors and their ligands as immunotherapy for cancer

INTRODUCTION

Natural killer (NK) cells are an important component of the innate immune system that play a key role in host immunity against cancer. NK cell recognition and activation is based on cell surface receptors recognizing specific ligands that are expressed on many types of tumor cells. Some of these receptors are capable of activating NK cell function while other receptors inhibit NK cell function. Therapeutic approaches to treat cancer have been developed based on preventing NK cell inhibition or using NK cell receptors and their ligands to activate NK cells or T cells to destroy tumor cells.

AREAS COVERED

This article describes the various strategies for targeting NK cell receptors and NK cell receptor ligands using multivalent proteins to activate immunity against cancer.

EXPERT OPINION

NK cell receptors work in synergy to activate NK cell effector responses. Effective anti-cancer strategies will need to not only kill tumor cells but must also lead to the destruction of the tumor microenvironment. Immunotherapy based on NK cells and their receptors has the capacity to accomplish this through triggering lymphocyte cytotoxicity and cytokine production.

Anti-human CD138 monoclonal antibodies and their bispecific formats: generation and characterization

Syndecan-1 (CD138), a heparan sulfate proteoglycan, acts as a co-receptor for growth factors and chemokines and is a molecular marker associated with the epithelial-mesenchymal transition during development and carcinogenesis. In this study, we generated two specific mouse anti-human CD138 monoclonal antibodies (mAbs, clone ID: 480CT5.4.3, 587CT7.3.6.5) using hybridoma technology and identified their immunological characteristics. After hybridoma sequencing, the single-chain variable fragments (ScFvs) cloned from two hybridoma cells were combined with anti-CD3 OKT-3 ScFv to generate two recombinant bispecific antibodies (h-STL002, m-STL002) against CD138 and CD3 molecules, respectively. The bispecific antibodies were able to specifically target CD138 + multiple myeloma (MM) cells and CD3 + T cells, and showed the potent cytotoxicity against MM RPMI-8226 cell line through T cell activation. However, these bispecific antibodies without T cells did not cause toxic side effect on MM cells. Overall, the two hybridoma clones and their bispecific formats have great potential to promote diagnosis and immunotherapy of plasma cell malignancy.

The Role of Immunotherapy in Multiple Myeloma

Multiple myeloma is the second most common hematologic malignancy. The treatment of this disease has changed considerably over the last two decades with the introduction to the clinical practice of novel agents such as proteasome inhibitors and immunomodulatory drugs. Basic research efforts towards better understanding of normal and missing immune surveillence in myeloma have led to development of new strategies and therapies that require the engagement of the immune system. Many of these treatments are under clinical development and have already started providing encouraging results. We, for the second time in the last two decades, are about to witness another shift of the paradigm in the management of this ailment. This review will summarize the major approaches in myeloma immunotherapies.

Targeting the Bone Marrow Microenvironment

Unprecedented advances in multiple myeloma (MM) therapy during the last 15 years are predominantly based on our increasing understanding of the pathophysiologic role of the bone marrow (BM) microenvironment. Indeed, new treatment paradigms, which incorporate thalidomide, immunomodulatory drugs (IMiDs), and proteasome inhibitors, target the tumor cell as well as its BM microenvironment. Ongoing translational research aims to understand in more detail how disordered BM-niche functions contribute to MM pathogenesis and to identify additional derived targeting agents. One of the most exciting advances in the field of MM treatment is the emergence of immune therapies including elotuzumab, daratumumab, the immune checkpoint inhibitors, Bispecific T-cell engagers (BiTes), and Chimeric antigen receptor (CAR)-T cells. This chapter will review our knowledge on the pathophysiology of the BM microenvironment and discuss derived novel agents that hold promise to further improve outcome in MM.