Elotuzumab in combination with lenalidomide and dexamethasone in patients with relapsed multiple myeloma: final phase 2 results from the randomised, open-label, phase 1b-2 dose-escalation study

Immunotherapeutics in Multiple Myeloma: How Can Translational Mouse Models Help?

Multiple myeloma (MM) is usually diagnosed in older adults at the time of immunosenescence, a collection of age-related changes in the immune system that contribute to increased susceptibility to infection and cancer. The MM tumor microenvironment and cumulative chemotherapies also add to defects in immunity over the course of disease. In this review we discuss how mouse models have furthered our understanding of the immune defects caused by MM and enabled immunotherapeutics to progress to clinical trials, but also question the validity of using immunodeficient models for these purposes. Immunocompetent models, in particular the 5T series and Vk^⁎MYC models, are increasingly being utilized in preclinical studies and are adding to our knowledge of not only the adaptive immune system but also how the innate system might be enhanced in anti-MM activity. Finally we discuss the concept of immune profiling to target patients who might benefit the most from immunotherapeutics, and the use of humanized mice and 3D culture systems for personalized medicine.

New Drugs in Multiple Myeloma

Multiple myeloma is diagnosed in over 100,000 patients each year worldwide, has an increasing incidence and prevalence in many regions, and follows a relapsing course, making it a significant and growing healthcare challenge. Recent basic, translational, and clinical studies have expanded our therapeutic armamentarium, which now consists of alkylating agents, corticosteroids, deacetylase inhibitors, immunomodulatory agents, monoclonal antibodies, and proteasome inhibitors. New drugs in these categories, and additional agents, including both small and large molecules, as well as cellular therapies, are under development that promise to further expand our capabilities and bring us closer to the cure of this plasma cell dyscrasia.

Immunotherapeutic Approaches for Multiple Myeloma: Where Are We Now?

PURPOSE OF REVIEW

The treatment landscape for multiple myeloma has evolved rapidly with the availability of multiple new drugs; however, although patient survival has improved, the disease remains incurable. Multiple myeloma is characterized by the unregulated growth of malignant plasma cells accompanied by immune dysfunction as well as disrupted immune surveillance mechanisms. Here, we analyze clinical modalities, with a focus on monoclonal antibodies and adoptive cellular therapy that enhance patients' immune systems and overcome these defects.

RECENT FINDINGS

Early clinical trials with PD-1 inhibitors were promising, but randomized phase III trials with immunomodulatory drugs showed increased toxicities. Monoclonal antibodies targeting surface antigens led to substantial clinical efficiency in relapsed myeloma. Chimeric antigen receptor (CAR) T cell therapy for multiple myeloma represents a significant advance, as exciting and dramatic responses in early clinical trials have been seen. Immunotherapeutic approaches are promising and can augment or replace the current standard of care, with the potential to offer extended survival for myeloma patients.

Therapeutic antibodies for multiple myeloma

In recent years, many antibody therapies for multiple myeloma have been developed. Antibodies against SLAMF7, CD38, B-cell maturation antigen and PD-1 have been developed and clinical trials are currently under way. As of July 2017, antibodies clinically available in Japan for the treatment of multiple myeloma are elotuzumab against SLAMF7 and daratumumab against CD38. Elotuzumab is a humanized IgG1-kappa monoclonal antibody targeting human SLAMF7. SLAMF7 is a cell surface glycoprotein receptor highly expressed on multiple myeloma cells, and it is also expressed on natural killer cells and is critical for natural killer function. Binding of elotuzumab to natural killer cells leads to activation of natural killer cells, resulting in antibody-dependent cell-mediated cytotoxicity of elotuzumab-bound multiple myeloma cells, but not complement-dependent cytotoxicity. The result of a randomized phase III trial of elotuzumab+lenalidomide+dexamethasone (ELOQUENT-2) reduced the risk of disease progression/death by 30% vs lenalidomide+dexamethasone in relapse/refractory multiple myeloma. Daratumumab is a human anti-CD38 IgG1-kappa antibody. CD38 is expressed ubiquitously virtually in all tissues that are highly expressed on plasma cells and it represents an attractive target for immunotherapy using monoclonal antibodies. In the phase III CASTOR trial, patients treated with daratumumab+bortezomib+dexamethasone had a better CR rate and progression-free survival rate compared with bortezomib+dexamethasone-treated patients (29% vs 10%, median progression-free survival: 16.7 vs 7.1 months, respectively). Moreover, in the phase III POLLUX trial, patients treated with daratumumab+lenalidomide+dexamethasone had a better response and progression-free survival (CRR or better: 55% vs 23%, 30-month progression-free survival: 58% vs 35%), compared with lenalidomide+dexamethasone-treated patients.

Cell-based immunotherapy approaches for multiple myeloma

Despite the arrival of novel therapies, multiple myeloma (MM) remains incurable and new treatment options are needed. Chimeric antigen receptor (CAR) T cells are genetically modified T cells that express a CAR directed against specific tumour antigens. CAR T cells are able to kill target tumour cells and may result in long-lasting immune responses in vivo. The rapid development of CAR technologies has led to clinical trials in haematological cancers including MM, and CAR T cells might evolve into a standard treatment in the next few years. Only small patient cohorts with relapsed or refractory disease have so far been investigated, but promising preliminary results with high response rates have been  obtained in phase I clinical trials with B cell maturation antigen (BCMA), CD19, CD38 and κ-light-chain CAR T cells. Additional preclinical studies on CD38 and SLAMF7-CAR T cells in MM treatment yielded preclinical results that merit further investigation. Beyond the T cell approach, recent studies have focussed on CAR natural killer (NK) cells in order to increase the reactivity of these effector cells. Finally, to investigate the targeting of intracellular antigens, cellular therapies based on engineered T cell receptors (TCRs) are in development. In this review, we discuss results from preclinical and early-phase clinical trials testing the feasibility and safety of CAR T cell administration in MM, as well as early studies into approaches that utilise CAR NK cell and genetically modified TCRs.

Clinical and biological characteristics of myeloma patients influence response to elotuzumab combination therapy

Based on ELOQUENT-2, combination therapy with the monoclonal antibody elotuzumab was approved for relapsed/refractory multiple myeloma in the US and Europe. However, outside clinical trials, the optimal integration of elotuzumab into the sequence of treatment lines remains to be determined. Therefore, we analyzed safety and efficacy of elotuzumab/immunomodulatory drug combinations in a real-life cohort of 33 patients from our institution. The most frequent grade 3/4 adverse event was lymphopenia which did not increase the incidence of viral reactivations. After a median of four prior treatment lines, an overall response rate of 60% and a median progression-free survival (PFS) of 8 months were observed. The presence of cytogenetic high-risk status had no impact on PFS while low disease burden and high numbers of natural killer (NK)-cells at treatment initiation were associated with longer PFS. We observed an extramedullary relapse in three patients, associated with reduced expression of the elotuzumab target antigen SLAMF7 on extramedullary myeloma cells in one patient. Thus, biomarkers like disease burden, NK-cell count and SLAMF7 expression on myeloma cells may help to define myeloma patients with high likelihood to respond to elotuzumab treatment. Prospective trials investigating these biomarkers in larger patient cohorts are highly warranted.

Mechanisms of NK Cell Activation and Clinical Activity of the Therapeutic SLAMF7 Antibody, Elotuzumab in Multiple Myeloma

Multiple myeloma (MM) is a bone marrow plasma cell neoplasm and is the second most-common hematologic malignancy. Despite advances in therapy, MM remains largely incurable. Elotuzumab is a humanized IgG1 monoclonal antibody targeting SLAMF7, which is highly expressed on myeloma cells, and the antibody is approved for the treatment of relapsed and/or refractory (RR) MM in combination with lenalidomide and dexamethasone. Elotuzumab can stimulate robust antibody-dependent cellular cytotoxicity (ADCC) through engaging with FcγRIIIA (CD16) on NK cells and antibody-dependent cellular phagocytosis (ADCP) by macrophages. Interestingly, SLAMF7 is also expressed on cytolytic NK cells, which also express the requisite adaptor protein, EAT-2, to mediate activation signaling. Accumulating evidence indicates that antibody crosslinking of SLAMF7 on human and mouse NK cells can stimulate EAT-2-dependent activation of PLCγ, ERK, and intracellular calcium mobilization. The binding of SLAMF7 by elotuzumab can directly induce signal transduction in human NK cells, including co-stimulation of the calcium signaling triggered through other surface receptors, such as NKp46 and NKG2D. In RRMM patients, elotuzumab monotherapy did not produce objective responses, but did enhance the activity of approved standard of care therapies, including lenalidomide or bortezomib, which are known to enhance anti-tumor responses by NK cells. Taken together, these preclinical results and accumulating experience in the clinic provide compelling evidence that the mechanism of action of elotuzumab in MM patients involves the activation of NK cells through both CD16-mediated ADCC and direct co-stimulation via engagement with SLAMF7, as well as promoting ADCP by macrophages. We review the current understanding of how elotuzumab utilizes multiple mechanisms to facilitate immune-mediated attack of myeloma cells, as well as outline goals for future research.

The challenges of checkpoint inhibition in the treatment of multiple myeloma

Despite significant improvements in the overall survival of patients with multiple myeloma (MM) over the past 15 years, the disease remains incurable. Treatment options are limited for patients who have relapsed or are refractory to immunomodulatory drugs (IMiDs), proteasome inhibitors, and monoclonal antibodies. In these patients, immunotherapies such as checkpoint inhibitors, oncolytic vaccines, and chimeric antigen receptor (CAR) T cells provide a potentially effective alternative treatment. While checkpoint inhibitors are effective in prolonging overall survival in some patients with advanced solid cancers and Hodgkin lymphoma, they have not demonstrated significant activity as a single agent in MM. In fact the combination of checkpoint inhibitors with IMiDs was recently found to increase the risk of death in myeloma patients. These challenges highlight the need for a better understanding of immune dysregulation in myeloma patients, and the mechanisms of action of- and resistance to- checkpoint inhibitors. In this review, we summarize immune dysfunction in patients with MM, and review the preclinical and clinical data regarding checkpoint inhibitors in myeloma. We conclude by proposing strategies to improve the efficacy and safety of checkpoint inhibitors in this population.

Glucocorticoids in multiple myeloma: past, present, and future

Glucocorticoids are a backbone of treatment for multiple myeloma in both the upfront and relapsed/refractory setting. While glucocorticoids have single agent activity in multiple myeloma, in the modern era, they are paired with novel agents to induce high clinical response rates. On the other hand, toxicities of steroid therapy limit high dose delivery and impact patient quality of life. We provide a history of steroid use in multiple myeloma with the aim to understand how steroids have emerged and persisted in the treatment of multiple myeloma. We review mechanisms of glucocorticoid sensitivity and resistance and highlight potential future directions to evaluate steroid responsiveness. Further research in this area will aid in optimizing steroid utilization and help determine when glucocorticoid therapy may no longer benefit patients.

Elotuzumab monotherapy in patients with smouldering multiple myeloma: a phase 2 study

Smouldering multiple myeloma (SMM) is associated with increased risk of progression to multiple myeloma within 2 years, with no approved treatments. Elotuzumab has been shown to promote natural killer (NK) cell stimulation and antibody-dependent cellular cytotoxicity (ADCC) in vitro. CD56^dim (CD56^dim /CD16⁺ /CD3^- /CD45⁺ ) NK cells represent the primary subset responsible for elotuzumab-induced ADCC. In this phase II, non-randomized study (NCT01441973), patients with SMM received elotuzumab 20 mg/kg intravenously (cycle 1: days 1, 8; monthly thereafter) or 10 mg/kg (cycles 1, 2: weekly; every 2 weeks thereafter). The primary endpoint was the relationship between baseline proportion of bone marrow-derived CD56^dim NK cells and maximal M protein reduction; secondary endpoints included overall response rate (ORR) and progression-free survival (PFS). Fifteen patients received 20 mg/kg and 16 received 10 mg/kg; combined data arepresented. At database lock (DBL, September 2014), no association was found between baseline CD56^dim NK cell proportion and maximal M protein reduction. With minimum 28 months' follow-up (DBL: January 2016), ORR (90% CI) was 10% (2·7-23·2) and 2-year PFS rate was 69% (52-81%). Upper respiratory tract infections occurred in 18/31 (58%) patients. Four (13%) patients experienced infusion reactions, all grade 1-2. Elotuzumab plus lenalidomide/dexamethasone is under investigation for SMM.

A look at treatment strategies for relapsed multiple myeloma

INTRODUCTION

Multiple myeloma treatment considerably improved during the past decade, thanks to novel effective drugs, a better understanding of myeloma biology and clonal heterogeneity, and an improved management of toxicities. The choice of regimen at relapse is usually based on prior response, toxicities, age and comorbidities of relapsed patients. Areas covered: A review was performed of the most recent and effective therapeutic strategies for the relapsed myeloma setting, by documenting the latest clinical evidence from phase II and III clinical trials. Of note, new drugs, such as carfilzomib, ixazomib, pomalidomide, daratumumab and elotuzumab, alone or in combinations in doublet or triplet regimens, have greatly increased the treatment armamentarium against myeloma. Expert commentary: Impressive results have been obtained with new drugs in relapsed patients. Besides number of prior therapies and previous response, other factors play a crucial role in the selection of therapy. Re-challenge with previous drugs can be adopted if previous responses lasted at least 6 months and therapy had induced low toxicity. Patients' risk status can further help to appropriately select therapy at relapse, and clinical trials will allow physicians to use newer targeted therapies and immune-therapies, thus delaying palliative approaches to later relapse stages.

Elotuzumab-induced interstitial lung disease: the first case report

Elotuzumab, a humanized immunoglobulin G1 monoclonal antibody targeted against signaling lymphocytic activation molecule F7 (SLAMF7), has recently been used in combination with lenalidomide and dexamethasone for the treatment of patients with relapsed or refractory multiple myeloma. The clinical characteristics of drug-induced interstitial lung disease (ILD) due to elotuzumab have not been clarified. In this report, we describe a patient with refractory multiple myeloma who received elotuzumab in combination with lenalidomide and dexamethasone in whom fatigue, fever and diffuse pulmonary infiltration developed. The patient had a history of long-term therapy with lenalidomide without pulmonary toxicity. Bronchoscopy with bronchoalveolar lavage was negative for infection, and transbronchial lung biopsies showed active alveolitis with lymphocytic infiltration and myxomatous change of the thick alveolar wall. After the discontinuation of elotuzumab and lenalidomide, the patient's clinical symptoms gradually improved, and spontaneous remission of the pulmonary infiltration was observed. Based on the chest CT and lung pathology findings, the exclusion of infection and pulmonary edema, and according to the clinical course, we established a diagnosis of drug-induced ILD due to elotuzumab. Clinicians should bear in mind the potential for pulmonary toxicity in patients receiving elotuzumab-containing therapy.

Monoclonal Antibodies and Multiple Myeloma: All in All It's Just Another Brick in the Wall?

This commentary offers insight about the recent review by the European Medicines Agency on the approval of daratumumab for the treatment of adult patients with multiple myeloma.

Anti-CD38 and anti-SLAMF7: the future of myeloma immunotherapy

INTRODUCTION

the high expression of a number of surface antigens on malignant plasma cells, the bone marrow micro-environment and immune effector T cells, makes these appealing targets for immune therapy with monoclonal antibodies (mAbs). Areas covered: Two mAbs, anti-CD38 daratumumab (Dara) and anti-SLAMF7 elotuzumab (Elo), have achieved recent regulatory approval for relapsed or refractory MM (RRMM) and are currently being explored as possible treatment options in novel combinations and different settings. This review discusses the current landscape and possible development of anti-CD38 and anti-SLAMF7 mAbs. Expert commentary: Three phase III trials demonstrated a significant advantage in terms of response and PFS when Dara or Elo are combined with lenalidomide-dexamethsone (Rd) or bortezomib-dexamethsone (Vd), in comparison to doublet regimens, for patients with RRMM. Treatment algorithms including Dara- or Elo-based triplets may be defined on the basis of disease and patients' characteristics, as well as of their prior exposure to different classes of novel agents. Evaluation of these agents in new combination regimens, including second and third generation PIs and IMiDs, are under investigation. Moreover, use of mAbs in phases of the disease where the immune system is less compromised, such as newly diagnosed MM or even high-risk smoldering myeloma, appears logical.

Systematic review and meta-analysis of the efficacy and safety of novel monoclonal antibodies for treatment of relapsed/refractory multiple myeloma

Although two newly launched monoclonal antibodies (mAbs), elotuzumab and daratumumab, performed well in patients with relapsed or relapsed/refractory multiple myeloma (RRMM), their efficacy and safety remain uncertain. We therefore performed a systematic review and meta-analysis of the most recent clinical trials that evaluated elotuzumab and/or daratumumab for the treatment of patients with RRMM. Our meta-analysis included 13 clinical trials with 2,402 patients participating. The overall response rate (ORR) was 57% (95% confidence interval [CI]: 38-76%), and the at least very good partial response rate (VGPR) was 32% (95% CI: 19-46%). mAb-based regimens prolonged progression-free survival (PFS, hazard ratio: 0.52, 95% CI: 0.36-0.75) compared to non-mAb-based regimens. Additionally, the efficacy of triplet regimens was superior to that of single or doublet regimens. The same trend was observed in a subgroup analysis of daratumumab and elotuzumab. The most common grade 3/4 adverse events included neutropenia, lymphopenia, thrombocytopenia, anemia, leukopenia, pneumonia, and fatigue. Elotuzumab and daratumumab improved the ORR, at least VGPR, and PFS compared to non-mAb-based regimens. In a pooled analysis, both mAbs had promising efficacy and safety profiles, particularly in triplet regimens. The same trend was observed in daratumumab- and elotuzumab-based regimens. Daratumumab triplet therapy (daratumumab, lenalidomide, and dexamethasone) was superior to other triplet regimens for the treatment of RRMM, and daratumumab monotherapy was more effective than either single agent in heavily pretreated MM patients, suggesting CD38 is an effective target for treatment of RRMM. Additional clinical studies of elotuzumab and daratumumab will be required to validate these results.

Signaling lymphocytic activation molecules Slam and cancers: friends or foes?

Signaling Lymphocytic Activation Molecules (SLAM) family receptors are initially described in immune cells. These receptors recruit both activating and inhibitory SH2 domain containing proteins through their Immunoreceptor Tyrosine based Switch Motifs (ITSMs). Accumulating evidence suggest that the members of this family are intimately involved in different physiological and pathophysiological events such as regulation of immune responses and entry pathways of certain viruses. Recently, other functions of SLAM, principally in the pathophysiology of neoplastic transformations have also been deciphered. These new findings may prompt SLAM to be considered as new tumor markers, diagnostic tools or potential therapeutic targets for controlling the tumor progression. In this review, we summarize the major observations describing the implications and features of SLAM in oncology and discuss the therapeutic potential attributed to these molecules.

Elotuzumab for the Treatment of Relapsed or Refractory Multiple Myeloma, with Special Reference to its Modes of Action and SLAMF7 Signaling

Elotuzumab, targeting signaling lymphocytic activation molecule family 7 (SLAMF7), has been approved in combination with lenalidomide and dexamethasone (ELd) for relapsed/refractory multiple myeloma (MM) based on the findings of the phase III randomized trial ELOQUENT-2 (NCT01239797). Four-year follow-up analyses of ELOQUENT-2 have demonstrated that progression-free survival was 21% in ELd versus 14% in Ld. Elotuzumab binds a unique epitope on the membrane IgC2 domain of SLAMF7, exhibiting a dual mechanism of action: natural killer (NK) cell-mediated antibody-dependent cellular cytotoxicity (ADCC) and enhancement of NK cell activity. The ADCC is mediated through engagement between Fc portion of elotuzumab and FcgRIIIa/CD16 on NK cells. Enhanced NK cell cytotoxicity results from phosphorylation of the immunoreceptor tyrosine-based switch motif (ITSM) that is induced via elotuzumab binding and recruits the SLAM-associated adaptor protein EAT-2. The coupling of EAT-2 to the phospholipase Cg enzymes SH2 domain leads to enhanced Ca²⁺ influx and MAPK/Erk pathway activation, resulting in granule polarization and enhanced exocytosis in NK cells. Elotuzumab does not stimulate the proliferation of MM cells due to a lack of EAT-2. The inhibitory effects of elotuzumab on MM cell growth are not induced by the lack of CD45, even though SHP-2, SHP-1, SHIP-1, and Csk may be recruited to phosphorylated ITSM of SLAMF7. ELd improves PFS in patients with high-risk cytogenetics, i.e. t(4;14), del(17p), and 1q21 gain/amplification. Since the immune state is paralytic in advanced MM, the efficacy of ELd with minimal toxicity may bring forward for consideration of its use in the early stages of the disease.

Current developments in immunotherapy in the treatment of multiple myeloma

Multiple myeloma (MM) is the second most common hematologic malignancy and represents approximately 10% of all hematological neoplasms. Standard therapy consists of induction therapy followed by high-dose chemotherapy and autologous stem cell transplantation (ASCT) or, if ASCT cannot be performed, standard doublet, triplet, or quadruplet, novel agent-containing induction treatment until progression. Although MM is still regarded as mostly incurable by current standards, the development of several novel compounds, combination therapies, and immunotherapy approaches has raised great hopes about transforming MM into an indolent, chronic disease and possibly achieving a cure for individual patients. Several new inhibitory and immunological agents have been approved or are under intensive investigation and may lead to new therapeutic options for patients with relapsed/refractory MM, for patients ineligible for ASCT, and for patients after ASCT. Especially in the field of immunotherapy, including monoclonal antibodies, checkpoint inhibition, and chimeric antigen receptor T cells, current advances are rapid and highly promising. This review aims to summarize the newest and most promising immunotherapeutic agents for MM, their clinical efficacy, their adverse event (AE) profiles, and the ways in which these AEs can best be overcome or avoided. Cancer 2018;124:2075-85. © 2018 American Cancer Society.

Monoclonal Antibody Therapies for Hematological Malignancies: Not Just Lineage-Specific Targets

Today, monoclonal antibodies (mAbs) are a widespread and necessary tool for biomedical science. In the hematological cancer field, since rituximab became the first mAb approved by the Food and Drug Administration for the treatment of B-cell malignancies, a number of effective mAbs targeting lineage-specific antigens (LSAs) have been successfully developed. Non-LSAs (NLSAs) are molecules that are not restricted to specific leukocyte subsets or tissues but play relevant pathogenic roles in blood cancers including the development, proliferation, survival, and refractoriness to therapy of tumor cells. In consequence, efforts to target NLSAs have resulted in a plethora of mAbs-marketed or in development-to achieve different goals like neutralizing oncogenic pathways, blocking tumor-related chemotactic pathways, mobilizing malignant cells from tumor microenvironment to peripheral blood, modulating immune-checkpoints, or delivering cytotoxic drugs into tumor cells. Here, we extensively review several novel mAbs directed against NLSAs undergoing clinical evaluation for treating hematological malignancies. The review focuses on the structure of these antibodies, proposed mechanisms of action, efficacy and safety profile in clinical studies, and their potential applications in the treatment of hematological malignancies.

Isatuximab plus pomalidomide/dexamethasone versus pomalidomide/dexamethasone in relapsed/refractory multiple myeloma: ICARIA Phase III study design

Treatment for relapsed/refractory multiple myeloma (RRMM) remains an unmet need. Isatuximab, an anti-CD38 monoclonal antibody has shown efficacy and tolerability as a monotherapy and combination therapy in Phase I/II studies in RRMM. Here, we describe the design of the Phase III ICARIA-MM study (NCT02990338) which will evaluate isatuximab in combination with pomalidomide (Pom) and low-dose dexamethasone (dex) (Pom/dex) versus Pom/dex alone in RRMM. Patients will be randomized in a 1:1 ratio. The primary endpoint is progression-free survival. Response will be determined by an independent response review committee using IMWG criteria (2016) and safety will be assessed throughout. Approximately 300 patients (150 in each arm) are expected to enroll. The first patient was recruited in January 2017 and accrual is ongoing.

Advances in immunotherapy in multiple myeloma

PURPOSE OF REVIEW

Here, we explore the significant progress made in the treatment of multiple myeloma, focusing on immunotherapy and the promise it has offered to patients suffering from advanced disease.

RECENT FINDINGS

Multiple myeloma, a B-cell malignancy, is characterized by unregulated plasma cell growth in the bone marrow as well as strong immunosuppression in the tumor microenvironment. mAbs targeting tumor antigens overcome this, increasing T-cell activation, multiple myeloma cell death, and depth of response. Similarly, adoptive T-cell therapy aims to engineer or isolate tumor-specific T cells for a targeted approach. Finally, peptide and dendritic cell/tumor fusion vaccines reeducate the immune system, expanding the immune response and generating long-term memory to prevent relapse of disease. Many of these approaches have been combined with existing therapies to enhance antitumor immunity.

SUMMARY

Immunotherapeutic approaches have remarkably changed the treatment paradigm for multiple myeloma, and encouraging patient responses have warranted further investigation into mAbs, adoptive T-cell therapy, vaccines, and combination therapy.

A review discussing elotuzumab and its use in the second-line plus treatment of multiple myeloma

Monoclonal antibodies (mAb) represent a new frontier to treat newly diagnosed and relapsed-refractory multiple myeloma (MM). Elotuzumab, an mAb targeted SLAM7 in the plasma cells and natural killer cells surface, is the first mAb approved for the treatment of relapsed-refractory MM in combination with lenalidomide and dexamethasone. This approval was the final result of several preclinical and Phase I-II clinical studies leading to ELOQUENT-2 Phase III trial that demonstrated that elotuzumab adds a significant and durable value to standard therapy, paved the way of this new treatment strategy for MM. In this review we will describe elotuzumab mechanisms of action, clinical pharmacology and clinical studies that have led to these developments.

Emerging drugs and combinations to treat multiple myeloma

In the past few years, multiple targeted therapies and immunotherapies including second generation immunomodulatory drugs (pomalidomide) and proteasome inhibitors (carfilzomib, ixazomib), monoclonal antibodies and checkpoint inhibitors were approved for the treatment of myeloma or entered advanced phases of clinical testing. These agents showed significant activity in advanced myeloma and increased the available treatment strategies. Pomalidomide is well-tolerated and effective in patients with relapsed/refractory multiple myeloma who have exhausted any possible treatment with lenalidomide and bortezomib. Carfilzomib, a second-generation proteasome inhibitor, is active as a single agent and in combination with other anti-myeloma agents. Ixazomib is the first oral proteasome inhibitor to be evaluated in myeloma and is associated with a good safety profile and anti-myeloma activity in relapsed/refractory patients, even in those refractory to bortezomib. Monoclonal antibodies and immune checkpoint inhibitors are likely to play a major role in the treatment of myeloma over the next decade. In phase 3 studies, triplet regimens based on these agents combined with a backbone therapy (including lenalidomide, pomalidomide or bortezomib) were more efficacious than doublet regimens in patients with relapsed/refractory multiple myeloma, with limited additional toxic effects. This paper aims to provide an overview of the recent use of these agents for the treatment of myeloma, in particular focusing on the role of multi-agent combinations.

Emerging therapies for multiple myeloma: Application in older adults

Tremendous advances in the treatment of multiple myeloma have yielded improvements in survival in patients with multiple myeloma. A number of pivotal phase III trials have established the benefit of these newer agents in individuals with relapsed multiple myeloma. Because older adults are under-enrolled in clinical trials, clinical trial data may not be categorically generalizable to more vulnerable older adults. In this review, the applicability to older adults of recent clinical trials of newer agents in older adults with myeloma are examined, with attention to eligibility criteria, dosing of therapy, characteristics of the population, and subgroup analyses of older adults.

Immunotherapy in Multiple Myeloma

OBJECTIVES

To review the use of monoclonal antibodies (mAbs) in the treatment of multiple myeloma (MM) and the management of most common side effects.

DATA SOURCES

Review of journal articles related to mAbs in MM.

CONCLUSION

The therapeutic options for MM have improved dramatically and the development of mAbs has been associated with improvement in clinical outcomes and favorable toxicity profiles.

IMPLICATIONS FOR NURSING PRACTICE

With appropriate pre-medications and nursing management, mAbs are a well-tolerated treatment option for myeloma patients.

Interferon-alpha-based immunotherapies in the treatment of B cell-derived hematologic neoplasms in today's treat-to-target era

B cell lymphoma and multiple myeloma (MM) are the most common hematological malignancies which benefit from therapeutic monoclonal antibodies (mAbs)-based immunotherapies. Despite significant improvement on patient outcome following the use of novel therapies for the past decades, curative treatment is unavailable for the majority of patients. For example, the 5-year survival of MM is currently less than 50%. In the 1980s, interferon-α was used as monotherapy in newly diagnosed or previously treated MM with an overall response rate of 15-20%. Noticeably, a small subset of patients who responded to long-term interferon-α further achieved sustained complete remission. Since 1990, interferon-α-containing regimens have been used as a central maintenance strategy for patients with MM. However, the systemic administration of interferon-α was ultimately limited by its pronounced toxicity. To address this, the selective mAb-mediated delivery of interferon-α has been developed to enhance specific killing of MM and B-cell malignant cells. As such, targeted interferon-α therapy may improve therapeutic window and sustain responses, while further overcoming suppressive microenvironment. This review aims to reinforce the role of interferon-α by consolidating our current understanding of targeting interferon-α with tumor-specific mAbs for B cell lymphoma and myeloma.

Emerging combination therapies for the management of multiple myeloma: the role of elotuzumab

Treatment options for patients with multiple myeloma (MM) have increased during the past decade. Despite the significant advances, challenges remain on which combination strategies will provide the optimal response for any given patient. Defining optimal combination strategies and corresponding companion diagnostics, that will guide clinical decisions are required to target relapsed or refractory multiple myeloma (RRMM) in order to improve disease progression, survival and quality of life for patients with MM. Elotuzumab is a humanized monoclonal antibody that targets signaling lymphocytic activation molecule F7 (SLAMF7), approved by the US Food and Drug Administration (FDA) in 2015 and the European Medicines Agency in 2016 for the treatment of MM. SLAMF7 is expressed in normal and malignant plasma cells and has lower expression on natural killer (NK) cells. Experimental evidence indicates that elotuzumab exhibits anti-myeloma activity through 1) antibody-dependent cell-mediated cytotoxicity, 2) enhancing NK cells cytotoxicity and 3) interfering with adhesion of MM cells to bone marrow stem cells (BMSCs). Although elotuzumab has no single agent activity in patients with RRMM who have received one to three prior therapies, the combination of elotuzumab with anti-myeloma agents, such as immunomodulatory drugs-lenalidomide, or proteasome inhibitors (PIs)-bortezomib, remarkably improved the overall response rates and progression-free survival in MM patients with only minimal incremental toxicity. In brief, the clinical data for elotuzumab indicate that targeting SLAMF7 in combination with the use of conventional therapies is feasible and effective with a tolerable safety profile for the treatment of RRMM.

Current and developing synthetic pharmacotherapy for treating relapsed/refractory multiple myeloma

INTRODUCTION

The introduction of novel agents has significantly improved multiple myeloma (MM) patient outcome during the last two decades. MM received the most drug approvals for any one malignancy during this time period, both in the United States as well as in Europe. Areas covered: Proteasome inhibitors, immunomodulatory drugs, and monoclonal antibodies are prototype drug classes, which target both specific MM cell functions, as well as the tumor supportive bone marrow microenvironment, and represent current cornerstones of MM therapy. Importantly, the unprecedented extent and frequency of durable responses, in relapsed/refractory multiple myeloma (RRMM), in particular, is predominantly based on the combinatorial use of these agents with conventional chemotherapeutics or representatives of other drug classes. This article will summarize past landmark discoveries in MM that led to the dramatic progress of today's clinical practice. Moreover, developing strategies will be discussed that are likely to yet improve patient outcome even further. Expert opinion: Despite significant therapeutic advancements, MM remains an incurable disease. With several novel agents in the preclinical and early clinical pipeline, among those novel CD38 and BCMA mAbs, immune checkpoint inhibitors, as well as ricolinostat, selinexor, venetoclax, CAR-T cells, and vaccines, further advances in MM patient outcome are expected in the near future.

How I treat first relapse of myeloma

The standard treatment of relapsed multiple myeloma has been either lenalidomide-dexamethasone (RD) or bortezomib-dexamethasone (VD) but it is changing rapidly for 2 reasons. First, lenalidomide and bortezomib are currently used in frontline treatment and many patients become resistant to these agents early in the course of their disease. Second, 6 second-line new agents have been recently developed and offer new possibilities (pomalidomide, carfilzomib and ixazomib, panobinostat, elotuzumab, and daratumumab). Recent randomized studies have shown that triple combinations adding 1 of these new agents (except pomalidomide) to the RD or VD regimens were superior to the double combinations in terms of response rate and progression-free survival (PFS). Their place in the treatment of first relapse is discussed here. Among these agents, daratumumab is clearly a breakthrough and daratumumab-based combinations might become the preferred option in the near future. However, all of these drugs are expensive and are not available or affordable in all countries. We propose a decision algorithm for first relapse in fit patients with the objective of achieving the best PFS. The choice of salvage regimen is based on lenalidomide/bortezomib resistance, daratumumab availability, and cost. Autologous transplantation should be considered in younger patients if not used upfront.

The anti-SLAMF7 antibody elotuzumab mediates NK cell activation through both CD16-dependent and -independent mechanisms

Elotuzumab is a humanized therapeutic monoclonal antibody directed to the surface glycoprotein SLAMF7 (CS1, CRACC, CD319), which is highly expressed on multiple myeloma (MM) tumor cells. Improved clinical outcomes have been observed following treatment of MM patients with elotuzumab in combination with lenalidomide or bortezomib. Previous work showed that elotuzumab stimulates NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC), via Fc-domain engagement with FcγRIIIa (CD16). SLAMF7 is also expressed on NK cells, where it can transmit stimulatory signals. We tested whether elotuzumab can directly activate NK cells via ligation with SLAMF7 on NK cells in addition to targeting ADCC through CD16. We show that elotuzumab strongly promoted degranulation and activation of NK cells in a CD16-dependent manner, and a non-fucosylated form of elotuzumab with higher affinity to CD16 exhibited enhanced potency. Using F(ab')₂ or Fc-mutant forms of the antibody, the direct binding of elotuzumab to SLAMF7 alone could not stimulate measurable CD69 expression or degranulation of NK cells. However, the addition of soluble elotuzumab could costimulate calcium signaling responses triggered by multimeric engagement of NKp46 and NKG2D in a CD16-independent manner. Thus, while elotuzumab primarily stimulates NK cells through CD16, it can also transduce effective "trans"-costimulatory signals upon direct engagement with SLAMF7, since these responses did not require direct co-engagement with the activating receptors. Trans-costimulation by elotuzumab has potential to reduce activation thresholds of other NK cell receptors engaging with their ligands on myeloma target cell surfaces, thereby potentially further increasing NK cell responsiveness in patients.

Elotuzumab as a novel anti-myeloma immunotherapy

Treatment of multiple myeloma has undergone significant change in the last decade with the introduction of new immunomodulatory agents, proteasome inhibitors, and immunotherapeutic approaches. Elotuzumab is a humanized monoclonal antibody targeting CS1, which is a member of the SLAM (Signaling Lymphocyte Activation Molecule) family of proteins, expressed on the surface of myeloma plasma cells. Here we review the preclinical investigations that led to the development of elotuzumab and the clinical studies that resulted in its approval for the treatment of relapsed/refractory multiple myeloma. Although preclinical data looked very promising, elotuzumab monotherapy did not result in objective clinical responses in patients with relapsed/refractory multiple myeloma. However, combination treatment with immunomodulators and proteasome inhibitors resulted in substantial clinical activity in relapsed/refractory MM. Currently, there are several clinical trials ongoing investigating the role of elotuzumab in newly diagnosed myeloma patients and in patients receiving maintenance therapy.

Daratumumab, Elotuzumab, and the Development of Therapeutic Monoclonal Antibodies in Multiple Myeloma

There has been substantial progress in clinical outcomes for patients with multiple myeloma (MM). This encouraging trend derives in large part from the increasing number of effective therapeutic options and the ability because of this to achieve higher quality responses to treatment. The approval of both daratumumab and of elotuzumab in combination with lenalidomide and dexamethasone, in late 2015, was a notable achievement in the field, as daratumumab and elotuzumab represent the first monoclonal antibodies available for use in MM. Given their unique mechanisms of action and favorable side effect profiles, daratumumab and elotuzumab have considerable potential as therapeutic partners with agents in other drug classes and in different clinical settings ranging from newly diagnosed to relapsed disease. This review discusses the development of daratumumab and elotuzumab as well as other monoclonal antibodies currently being evaluated for use in MM.

A phase 1b study of isatuximab plus lenalidomide and dexamethasone for relapsed/refractory multiple myeloma

This phase 1b, open-label, dose-escalation study assessed the safety, efficacy, and pharmacokinetics of anti-CD38 monoclonal antibody isatuximab given in 2 schedules (3, 5, or 10 mg/kg every other week [Q2W] or 10 or 20 mg/kg weekly [QW] for 4 weeks and then Q2W thereafter [QW/Q2W]), in combination with lenalidomide 25 mg (days 1-21) and dexamethasone 40 mg (QW), in patients with relapsed/refractory multiple myeloma (RRMM). Patients received 28-day treatment cycles; the primary objective was to determine the maximum tolerated dose (MTD) of isatuximab with lenalidomide and dexamethasone. Fifty-seven patients (median 5 [range 1-12] prior regimens; 83% refractory to previous lenalidomide therapy) were treated. Median duration of dosing was 36.4 weeks; 15 patients remained on treatment at data cutoff. Isatuximab-lenalidomide-dexamethasone was generally well tolerated with only 1 dose-limiting toxicity reported (grade 3 pneumonia at 20 mg/kg QW/Q2W); the MTD was not reached. The most common isatuximab-related adverse events were infusion-associated reactions (IARs) (56%), which were grade 1/2 in 84% of patients who had an IAR and predominantly occurred during the first infusion. In the efficacy-evaluable population, the overall response rate (ORR) was 56% (29/52) and was similar between the 10 mg/kg Q2W and 10 and 20 mg/kg QW/Q2W cohorts. The ORR was 52% in 42 evaluable lenalidomide-refractory patients. Overall median progression-free survival was 8.5 months. Isatuximab exposure increased in a greater than dose-proportional manner; isatuximab and lenalidomide pharmacokinetic parameters appeared independent. These data suggest that isatuximab combined with lenalidomide and dexamethasone is active and tolerated in heavily pretreated patients with RRMM. This trial was registered at www.clinicaltrials.gov as #NCT01749969.

PD-1 blockade enhances elotuzumab efficacy in mouse tumor models

Elotuzumab, a humanized monoclonal antibody that binds human signaling lymphocytic activation molecule F7 (hSLAMF7) on myeloma cells, was developed to treat patients with multiple myeloma (MM). Elotuzumab has a dual mechanism of action that includes the direct activation of natural killer (NK) cells and the induction of NK cell-mediated antibody-dependent cellular cytotoxicity. This study aimed to characterize the effects of elotuzumab on NK cells in vitro and in patients with MM and to determine whether elotuzumab antitumor activity was improved by programmed death receptor-1 (PD-1) blockade. Elotuzumab promoted NK cell activation when added to a coculture of human NK cells and SLAMF7-expressing myeloma cells. An increased frequency of activated NK cells was observed in bone marrow aspirates from elotuzumab-treated patients. In mouse tumor models expressing hSLAMF7, maximal antitumor efficacy of a murine immunoglobulin G2a version of elotuzumab (elotuzumab-g2a) required both Fcγ receptor-expressing NK cells and CD8⁺ T cells and was significantly enhanced by coadministration of anti-PD-1 antibody. In these mouse models, elotuzumab-g2a and anti-PD-1 combination treatment promoted tumor-infiltrating NK and CD8⁺ T-cell activation, as well as increased intratumoral cytokine and chemokine release. These observations support the rationale for clinical investigation of elotuzumab/anti-PD-1 combination therapy in patients with MM.

Preclinical data support leveraging CS1 chimeric antigen receptor T-cell therapy for systemic light chain amyloidosis

BACKGROUND AIMS

Light chain amyloidosis (AL) is a protein deposition disorder that is a result of a plasma cell dyscrasia, similar to multiple myeloma (MM). Immunotherapy is an attractive approach because of the low burden of disease, but the optimal target for AL is unclear. CS1 and B-cell maturation antigen (BCMA) are two potential targets because they are expressed on normal plasma cells and MM cells.

METHODS

We performed a prospective study evaluating bone marrow specimens of 20 patients with plasma cell diseases, 10 with AL and 10 with MM. We evaluated the clonal population of plasma cells for BCMA and CS1 expression. We designed a second-generation CS1 chimeric antigen receptor (CAR) construct, comprising a CS1 antigen-specific scFv, shortened hinge region and CD28 costimulatory domain. Purified central memory T cells were activated and transduced with a lentiviral vector encoding the CS1 CAR. Cytotoxicity was evaluated using ⁵¹Cr release assays. Five days after tumor inoculation, NSG mice were injected intravenously with CS1 CAR T cells.

RESULTS

Whereas CS1 is present on the plasma cells of AL patients, we found BCMA expression in AL to be markedly low. CS1 CAR T cells were cytotoxic against CS1 positive tumor cells and induced durable tumor regressions in mice.

DISCUSSION

Our work represents a novel application of CS1-directed CAR T cells while revealing that BCMA would not be a suitable target. We expect AL to be particularly susceptible to CAR T-cell therapy because of the low tumor burden in the bone marrow.

Daratumumab for the treatment of multiple myeloma

INTRODUCTION

Proteasome inhibitors and immunomodulatory drugs have contributed to the dramatic improvement in survival for patients with myeloma over the past decades. However, the disease typically relapses and new classes of drugs are needed. In 2015, two monoclonal antibodies were approved for the treatment of patients with relapsed multiple myeloma, and immunotherapy has rapidly become indispensable in the management of myeloma patients. Areas covered: Here, the authors discuss the published data regarding the mechanism of action, safety and clinical efficacy of the CD38-targeted monoclonal antibody daratumumab for the treatment of patients with multiple myeloma. Expert opinion: Daratumumab is indicated for myeloma patients who have received at least 3 prior therapies, including bortezomib, lenalidomide and pomalidomide. In 2016, daratumumab in combination with lenalidomide and dexamethasone, or bortezomib and dexamethasone was approved for the treatment of patients with multiple myeloma who have received at least one prior therapy. Daratumumab displays an excellent safety profile. Moderate-grade infusion-related reactions occurring mostly during the first infusion are the main treatment-emergent adverse event. In the context of daratumumab therapy, attention should be paid to interference with blood compatibility testing and response assessment. Daratumumab-based combination therapies are currently under evaluation in relapsed and newly diagnosed patients.

A phase 2 safety study of accelerated elotuzumab infusion, over less than 1 h, in combination with lenalidomide and dexamethasone, in patients with multiple myeloma

Elotuzumab, an immunostimulatory SLAMF7-targeting monoclonal antibody, induces myeloma cell death with minimal effects on normal tissue. In a previous phase 3 study in patients with relapsed/refractory multiple myeloma (RRMM), elotuzumab (10 mg/kg, ∼3-h infusion), combined with lenalidomide and dexamethasone, demonstrated durable efficacy and acceptable safety; 10% (33/321) of patients had infusion reactions (IRs; Grade 1/2: 29; Grade 3: 4). This phase 2 study (NCT02159365) investigated an accelerated infusion schedule in 70 patients with newly diagnosed multiple myeloma or RRMM. The primary endpoint was cumulative incidence of Grade 3/4 IRs by completion of treatment Cycle 2. Dosing comprised elotuzumab 10 mg/kg intravenously (weekly, Cycles 1-2; biweekly, Cycles 3+), lenalidomide 25 mg (daily, Days 1-21), and dexamethasone (28 mg orally and 8 mg intravenously, weekly, Cycles 1-2; 40 mg orally, weekly, Cycles 3+), in 28-day cycles. Premedication with diphenhydramine, acetaminophen, and ranitidine (or their equivalents) was given as in previous studies. If no IRs occurred, infusion rate was increased in Cycle 1 from 0.5 to 2 mL/min during dose 1 (∼2 h 50 min duration) to 5 mL/min for the entire infusion by dose 3 and also during all subsequent infusions (∼1-h duration). Median number of treatment cycles was six. No Grade 3/4 IRs occurred; only one Grade 1 and one Grade 2 IR occurred, both during the first infusion. These data support the safety of a faster infusion of elotuzumab administered over ∼1 h by the third dose, providing a more convenient alternative dosing option for patients.

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.

Therapy for Relapsed Multiple Myeloma: Guidelines From the Mayo Stratification for Myeloma and Risk-Adapted Therapy

Life expectancy in patients with multiple myeloma is increasing because of the availability of an increasing number of novel agents with various mechanisms of action against the disease. However, the disease remains incurable in most patients because of the emergence of resistant clones, leading to repeated relapses of the disease. In 2015, 5 novel agents were approved for therapy for relapsed multiple myeloma. This surfeit of novel agents renders management of relapsed multiple myeloma more complex because of the occurrence of multiple relapses, the risk of cumulative and emergent toxicity from previous therapies, as well as evolution of the disease during therapy. A group of physicians at Mayo Clinic with expertise in the care of patients with multiple myeloma regularly evaluates the evolving literature on the biology and therapy for multiple myeloma and issues guidelines on the optimal care of patients with this disease. In this article, the latest recommendations on the diagnostic evaluation of relapsed multiple myeloma and decision trees on how to treat patients at various stages of their relapse (off study) are provided together with the evidence to support them.

Clinical potential of SLAMF7 antibodies - focus on elotuzumab in multiple myeloma

Elotuzumab is one of the first monoclonal antibodies to be approved for the treatment of multiple myeloma. It is a humanized immunoglobulin G kappa (IgGκ) antibody that targets signaling lymphocytic activation molecule family member 7 (SLAMF7), a surface marker that is highly expressed on normal and malignant plasma cells. This review summarizes the preclinical and clinical data that led to the approval of elotuzumab, along with a discussion on the ongoing and future clinical investigations.

Is immunotherapy here to stay in multiple myeloma?

Immune escape and impaired immune surveillance have been identified as emerging hallmarks of cancer.1 Multiple myeloma represents a genuine example of disrupted immune surveillance characterized by: impaired antibody production, deregulation of the T and natural killer cell compartment, disruption of antigen presentation machinery, upregulation of inhibitory surface ligands, and recruitment of immunosuppressive cells. Although the potential value of immunotherapeutic interventions had a clear antecedent in the graft-versus-myeloma effect induced by allogeneic stem cell transplant and donor lymphocyte infusions, it is only recently that this field has faced a real revolution. In this review we discuss the current results obtained with immune approaches in patients with multiple myeloma that have placed this disease under the scope of immuno-oncology, bringing new therapeutic opportunities for the treatment of multiple myeloma patients.

Lenalidomide and low-dose dexamethasone (Rd) versus bortezomib, melphalan, prednisone (VMP) in elderly newly diagnosed multiple myeloma patients: A comparison of two prospective trials

There are currently no direct head-to-head clinical trials evaluating bortezomib-melphalan-prednisone (VMP) versus lenalidomide and low-dose dexamethasone (Rd). VMP (257 cases) and Rd (222 cases) arms of two randomized phase III trials were employed to assess the treatment influence on outcome in untreated elderly MM patients. Progression free survival (PFS) and overall survival (OS) were the primary and secondary end-points, respectively, and were investigated according to treatments administered over a 60-months follow-up period. While VMP significantly reduced the disease progression rate between enrolment and 12 months of follow-up, no difference between the two schedules was found between 12 and 32 months. After 32 months, Rd-treated patients had a lower incidence of disease progression. A statistically significant higher OS rate was seen in the VMP arm, which was maintained after data adjustment for potential confounders. Both approaches showed acceptable toxicity profiles. The profound tumor reduction by VMP over Rd justifies the initial higher PFS rate in favor of the bortezomib schedule, while the Rd regimen overcomes this evident initial drawback in reducing the tumor burden by long-term drug administration, gaining a subsequent improved disease control. VMP is associated with a significant reduced risk of death. This study may help physicians make a more informed therapy choice.

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.

Triplet combinations in relapsed/refractory myeloma: update on recent phase 3 trials

INTRODUCTION

Multiple myeloma (MM) is a rare hematologic disease of antibody-secreting plasma cells. Our understanding of the pathogenesis of this malignancy has improved greatly, and at the same time, we have access to new and more effective treatments options. Over the last 5 years, a spectrum of novel therapies with different mechanisms of action, including third-generation immunomodulatory drugs (pomalidomide), second generation proteasome inhibitors (carfilzomib and ixazomib), a histone deacetylase inhibitor (panobinostat) and monoclonal antibodies (mAbs) (elotuzumab and daratumumab) has transformed our approach to the treatment of patients with relapsed/refractory MM (RRMM). Areas covered: In this review, we will summarize the characteristics of the new drugs used in RRMM with a specific focus on recent phase 3 trials of triplet combinations in this setting and the rationale behind the selection of one regimen over another. Expert commentary: Several recent phase III trials conducted with patients with RRMM have demonstrated that triplet combinations are associated with a deeper response and an increased duration of response compared to standard treatments. These effective regimens may control the emerging drug resistant clones leading to progression. However, they have distinct toxicity profiles, which need to be taken into account by patients and care givers. The landscape of RRMM is changing rapidly, and new standards of care are proposed.