Monoclonal Antibodies for the Treatment of Multiple Myeloma: An Update

Comprehensive safety evaluation of isatuximab in multiple myeloma using disproportionality analysis of FAERS and meta-analysis of randomized controlled trials

Isatuximab, an anti-CD38 monoclonal antibody, has been shown to induce apoptosis in multiple myeloma (MM) cells and is effective in both relapsed/refractory and newly diagnosed MM cases. This study aims to compare the safety profile of isatuximab by examining a broader range of adverse events (AEs) using data from the FDA Adverse Event Reporting System (FAERS) and a meta-analysis of randomized controlled trials (RCTs). The study analyzed FAERS data up to March 2024, identifying suspected AEs using Preferred Terms. Data extraction from FAERS was conducted using OpenVigil-2.1-MedDRA-v24. Disproportionality analysis was performed by calculating the proportional reporting ratio (PRR) with Chi-square value, and the reporting odds ratio (ROR) with a 95% confidence interval (CI). For the meta-analysis, safety outcomes of isatuximab in adult patients were reviewed from RCTs sourced from databases such as PubMed, EMBASE, and ClinicalTrials.gov, employing a random-effects meta-analysis to determine the risk ratio (RR) with 95% CI. The meta-analysis protocol was registered with PROSPERO (CRD42022379632). Based on the FAERS quarterly reports, a total of 2,325 AE reports were identified, with a higher incidence in men (n = 1156, 49.7%) compared to women (n = 960, 41.3%). AEs commonly observed with isatuximab therapy included neutropenia, pneumonia, infusion-related reactions, thrombocytopenia, acute kidney injury, and anemia. In our meta-analysis of three RCTs involving 1,258 patients, 659 (52.4%) in the isatuximab treatment group experienced 1,135 AEs, with 58% classified as grade three or higher. In comparison, 599 (47.6%) patients in the control group reported 906 AEs, with 59% categorized as grade three or higher. Notably, the isatuximab group showed a statistically significant increased risk of grade three or higher neutropenia (RR = 2.13, 95% CI: 1.12-4.03, p = 0.0207) and a 30% increased risk of grade 3 or higher thrombocytopenia (RR = 1.30, 95% CI: 1.03-1.64, p = 0.0244). Isatuximab therapy was generally well-tolerated and exhibited a manageable safety profile. Considering these findings, future research might benefit from longer follow-up periods to capture delayed and less frequent AEs.

Acid-sensitive prodrugs; a promising approach for site-specific and targeted drug release

Drugs administered through conventional formulations are devoid of targeting and often spread to various undesired sites, leading to sub-lethal concentrations at the site of action and the emergence of undesired effects. Hence, therapeutic agents should be delivered in a controlled manner at target sites. Currently, stimuli-based drug delivery systems have demonstrated a remarkable potential for the site-specific delivery of therapeutic moieties. pH is one of the widely exploited stimuli for drug delivery as several pathogenic conditions such as tumor cells, infectious and inflammatory sites are characterized by a low pH environment. This review article aims to demonstrate various strategies employed in the design of acid-sensitive prodrugs, providing an overview of commercially available acid-sensitive prodrugs. Furthermore, we have compiled the progress made for the development of new acid-sensitive prodrugs currently undergoing clinical trials. These prodrugs include albumin-binding prodrugs (Aldoxorubicin and DK049), polymeric micelle (NC-6300), polymer conjugates (ProLindac™), and an immunoconjugate (IMMU-110). The article encompasses a broad spectrum of studies focused on the development of acid-sensitive prodrugs for anticancer, antibacterial, and anti-inflammatory agents. Finally, the challenges associated with the acid-sensitive prodrug strategy are discussed, along with future directions.

Combining CD38 antibody with CD47 blockade is a promising strategy for treating hematologic malignancies expressing CD38

Background

CD38 and CD47 are expressed in many hematologic malignancies, including multiple myeloma (MM), B-cell non-Hodgkin lymphoma (NHL), B-cell acute lymphoblastic leukemia (ALL), and B-cell chronic lymphocytic leukemia (CLL). Here, we evaluated the antitumor activities of CD38/CD47 bispecific antibodies (BsAbs).

Methods

Five suitable anti-CD38 antibodies for co-targeting CD47 and CD38 BsAb were developed using a 2 + 2 "mAb-trap" platform. The activity characteristics of the CD38/CD47 BsAbs were evaluated using in vitro and in vivo systems.

Results

Using hybridoma screening technology, we obtained nine suitable anti-CD38 antibodies. All anti-CD38 antibodies bind to CD38+ tumor cells and kill tumor cells via antibody-dependent cellular cytotoxicity (ADCC) and antibody-dependent cellular phagocytosis (ADCP). Five anti-CD38 antibodies (4A8, 12C10, 26B4, 35G5, and 65A7) were selected for designing CD38/CD47 BsAbs (IMM5605) using a "mAb-trap" platform. BsAbs had higher affinity and binding activity to the CD38 target than those to the CD47 target, decreasing the potential on-target potential and off-tumor effects. The CD38/CD47 BsAbs did not bind to RBCs and did not induce RBC agglutination; thus, BsAbs had much lower blood toxicity. The CD38/CD47 BsAbs had a greater ability to block the CD47/SIRPα signal in CD38+/CD47+ tumor cells than IMM01 (SIRPα Fc fusion protein). Through Fc domain engineering, CD38/CD47 BsAbs were shown to kill tumors more effectively by inducing ADCC and ADCP. IMM5605-26B4 had the strongest inhibitory effect on cellular CD38 enzymatic activity. IMM5605-12C10 had the strongest ability to directly induce the apoptosis of tumor cells. The anti-CD38 antibody 26B4 combined with the SIRPα-Fc fusion proteins showed strong antitumor effects, which were better than any of the mono-therapeutic agents used alone in the NCI-H929 cell xenograft model. The CD38/CD47 BsAbs exhibited strong antitumor effects; specifically, IMM5605-12C10 efficiently eradicated all established tumors in all mice.

Conclusion

A panel of BsAbs targeting CD38 and CD47 developed based on the "mAb-tarp" platform showed potent tumor-killing ability in vitro and in vivo. As BsAbs had lower affinity for binding to CD47, higher affinity for binding to CD38, no affinity for binding to RBCs, and did not induce RBC agglutination, we concluded that CD38/CD47 BsAbs are safe and have a satisfactory tolerability profile.

Immune checkpoint inhibitors for multiple myeloma immunotherapy

Multiple myeloma (MM) is related to immune disorders, recent studys have revealed that immunotherapy can greatly benefit MM patients. Immune checkpoints can negatively modulate the immune system and are closely associated with immune escape. Immune checkpoint-related therapy has attracted much attention and research in MM. However, the efficacy of those therapies need further improvements. There need more thoughts about the immune checkpoint to translate their use in clinical work. In our review, we aggregated the currently known immune checkpoints and their corresponding ligands, further more we propose various ways of potential translation applying treatment based on immune checkpoints for MM patients.

Biological research on the occurrence and development of multiple myeloma and its treatment

INTRODUCTION

To review the pathogenesis and treatment of multiple myeloma (MM). MM is a hematological malignancy with abnormal plasma cell proliferation in bone marrow. Due to the emergence of drug resistance, MM is still an incurable malignancy, which requires further exploration of pathogenesis and effective therapeutic targets.

METHODS

In this paper, the method of literature review is adopted to obtain the information about MM. Based on the literature, comprehensive and systematic review is made.

RESULTS

MM is a complex pathophysiological process with great heterogeneity, mainly reflected in genomic instability and bone marrow microenvironment. At present, the treatment of MM has made great progress, proteasome inhibitors and immunomodulatory drugs are widely used in clinic. Allogeneic stem cell transplantation may be the only promising cure for MM, and its high transplant-related mortality limits its clinical application.

CONCLUSIONS

The future of MM treatment lies in the development of more targeted therapies, novel immunotherapies, and a better understanding of the disease's molecular and genetic basis.

A phase 1/2, open-label, multicenter study of isatuximab in combination with cemiplimab in patients with lymphoma

Patients with relapsed or refractory lymphoma have limited treatment options, requiring newer regimens. In this Phase 1/2 study (NCT03769181), we assessed the safety, efficacy, and pharmacokinetics of isatuximab (Isa, anti-CD38 antibody) in combination with cemiplimab (Cemi, anti-programmed death-1 [PD-1] receptor antibody; Isa + Cemi) in patients with classic Hodgkin lymphoma (cHL), diffuse large B-cell lymphoma (DLBCL), and peripheral T-cell lymphoma (PTCL). In Phase 1, we characterized the safety and tolerability of Isa + Cemi with planned dose de-escalation to determine the recommended Phase 2 dose (RP2D). Six patients in each cohort were treated with a starting dose of Isa + Cemi to determine the RP2D. In Phase 2, the primary endpoints were complete response in Cohort A1 (cHL anti-PD-1/programmed death-ligand 1 [PD-L1] naïve), and objective response rate in Cohorts A2 (cHL anti-PD-1/PD-L1 progressors), B (DLBCL), and C (PTCL). An interim analysis was performed when the first 18 (Cohort A1), 12 (Cohort A2), 17 (Cohort B), and 11 (Cohort C) patients in Phase 2 had been treated and followed up for 24 weeks. Isa + Cemi demonstrated a manageable safety profile with no new safety signals. No dose-limiting toxicities were observed at the starting dose; thus, the starting dose of each drug was confirmed as the RP2D. Based on the Lugano 2014 criteria, 55.6% (Cohort A1), 33.3% (Cohort A2), 5.9% (Cohort B), and 9.1% (Cohort C) of patients achieved a complete or partial response. Pharmacokinetic analyses suggested no effect of Cemi on Isa exposure. Modest clinical efficacy was observed in patients with cHL regardless of prior anti-PD-1/PD-L1 exposure. In DLBCL or PTCL cohorts, interim efficacy analysis results did not meet prespecified criteria to continue enrollment in Phase 2 Stage 2. Isa + Cemi did not have a synergistic effect in these patient populations.

Habb-e-Asgandh Suppresses Cell Proliferation and Induces Apoptosis through Mitochondria Dysfunction in Multiple Myeloma Cells (RPMI8226)

OBJECTIVE

This study was conducted to assess the anti-neoplastic properties of Habb-e-Asgandh in multiple myeloma cells (RPMI8226).

METHODS

Multiple myeloma cells (RPMI8226) were cultured according to the ATCC's instruction. The anti-proliferative effect of HeA was assessed by MTT assay and proliferating cellnuclear antigen (PCNA) activity. Cell cycle analysis, cellular apoptosis, and mitochondria membrane potential analysis was done by flow cytometry. Total antioxidants, migratory potential, angiogenesis and inflammatory biomarkers were also estimated after treatment of RPMI8226 with HeA.

RESULTS

LD30 and LD50 dose of HeA was 0.3mg/ml and 0.5mg/ml respectively determined by MTT assay and also confirmed by a reduced PCNA activity. Cell cycle analysis of RPMI8226 cells revealed that sub-G0/G1 phase increases upon treatment with HeA alone or in combination with lenalidomide. Annexin V-FITC/PI is used to detect early apoptosis, late apoptosis and necrotic cells and results showed that percentage of apoptotic cells increased in RPMI8226 cells after treatment with HeA. Also, HeA induces loss of mitochondria membrane potential (MMP) in MM cells in-vitro as measured by cationic JC1 dye staining. Upon treatment, the abnormal overexpression of oncogenic protein, AKT serine/threonine kinase has also been reduced. Furthermore, anti-oxidants level also increased while migratory potential, angiogenesis and inflammation decreased in multiple myeloma cell line upon treatment with HeA.

CONCLUSION

Collectively, our results demonstrated that integrative therapy of habb-e-asgandh efficiently eliminates the need to use higher dose of lenalidomide for multiple myeloma treatment.

Phase 1 study of C-CAR088, a novel humanized anti-BCMA CAR T-cell therapy in relapsed/refractory multiple myeloma

BACKGROUND

Anti-B-cell maturation antigen (BCMA) chimeric antigen receptor T-cell (CAR T) therapy showed remarkable efficacy in patients with relapsed or refractory multiple myeloma (RRMM). This phase 1 dose-escalation and expansion study developed C-CAR088, a novel second-generation humanized anti-BCMA CAR T-cell therapy, and assessed the safety and efficacy of three dosages of C-CAR088 in patients with RRMM.

METHODS

Patients received lymphodepletion with three doses of cyclophosphamide (300 mg/m2) and three doses of fludarabine (30 mg/m2) on days -5, -4, and -3, followed by an infusion of C-CAR088 on day 0. Doses of 1.0×106, 3.0×106, and 6.0×106 CAR T cells/kg (±20%) were tested in the dose-escalation cohorts and expansion cohorts. The primary endpoint was treatment safety, including the rate of treatment-emergent adverse events after cell infusion. Secondary endpoints were the overall response rate and progression-free survival. The exploratory endpoints were the quantification of C-CAR088 CAR T cells, selection of cytokines and chemokines in blood, and measurement of tumor BCMA expression.

RESULTS

As of July 2, 2021, 31 patients had been infused with C-CAR088. Any grade cytokine release syndrome (CRS) occurred in 29 patients (93.5%), and grade 3 CRS occurred in 3 patients (9.7%). One patient from the high-dose group (4.5-6.0×106 CAR T cells/kg) developed grade 1 neurotoxicity. No dose-limiting toxicities were observed in any dose group, and all adverse events were reversible after proper management. The overall response, stringent complete response, complete response (CR), and very good partial response rates were 96.4%, 46.4%, 10.7%, and 32.1%, respectively. The CR rate in the medium-dose (3.0×106 CAR T cells/kg) and high-dose (4.5-6.0×106 CAR T cells/kg) groups was 54.5% and 71.4%, respectively. In the CR group, 15 (93.7%) patients achieved minimal residual disease (MRD) negativity (test sensitivity >1/10-5). All seven patients with double-hit or triple-hit multiple myeloma achieved MRD-negative CR.

CONCLUSIONS

The present study demonstrated that C-CAR088 had a good safety profile and high antitumor activity in patients with RRMM, constituting a promising treatment option for RRMM.

TRIAL REGISTRATION NUMBER

NCT03815383, NCT03751293, NCT04295018, and NCT04322292.

Regulation of CD38 on Multiple Myeloma and NK Cells by Monoclonal Antibodies

CD38 is highly expressed on multiple myeloma (MM) cells and plays a role in regulating tumor generation and development. CD38 monoclonal antibodies (mAbs) have been used as an effective therapy for MM treatment by various mechanisms, including complement-dependent cytotoxic effects, antibody-dependent cell-mediated cytotoxicity, antibody-dependent cellular phagocytosis, programmed cell death, enzymatic modulation, and immunomodulation. Although CD38 mAbs inhibit the proliferation and survival of MM cells, there are substantial side effects on antitumoral NK cells. The NK-mediated immune response needs to be further evaluated to minimize the adverse effects of NK cell loss. The killing effect of CD38 mAbs on CD38high NK cells should be minimized and the potential combination of CD38low/- NK cells and CD38 mAbs should be maximized to better benefit from their therapeutic efficacy against MM. CD38 mAb effects against MM can be maximized by combination therapies with immunomodulatory imide drugs (IMiDs), proteasome inhibitors (PIs), anti-programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) antibodies, or cellular therapies for the treatment of MM, especially in patients with relapsed or refractory MM (R/R MM) and drug-resistant MM.

Comparison of Clinical Characteristics and Genetic Aberrations of Plasma Cell Disorders in Thailand Population

Multiple myeloma is an incurable malignancy of plasma cells resulting from impaired terminal B cell development. Almost all patients with multiple myeloma eventually have a relapse. Many studies have demonstrated the importance of the various genomic mutations that characterize multiple myeloma as a complex heterogeneous disease. In recent years, next-generation sequencing has been used to identify the genomic mutation landscape and clonal heterogeneity of multiple myeloma. This is the first study, a prospective observational study, to identify somatic mutations in plasma cell disorders in the Thai population using targeted next-generation sequencing. Twenty-seven patients with plasma cell disorders were enrolled comprising 17 cases of newly diagnosed multiple myeloma, 5 cases of relapsed/refractory multiple myeloma, and 5 cases of other plasma cell disorders. The pathogenic mutations were found in 17 of 27 patients. Seventy percent of those who had a mutation (12/17 patients) habored a single mutation, whereas the others had more than one mutation. Fifteen pathogenic mutation genes were identified: ATM, BRAF, CYLD, DIS3, DNMT3A, FBXW7, FLT3, GNA13, IRF4, KMT2A, NRAS, SAMHD1, TENT5C, TP53, and TRAF3. Most have previously been reported to be involved in the RAS/MAPK pathway, the nuclear factor kappa B pathway, the DNA-repair pathway, the CRBN pathway, tumor suppressor gene mutation, or an epigenetic mutation. However, the current study also identified mutations that had not been reported to be related to myeloma: GNA13 and FBXW7. Therefore, a deep understanding of molecular genomics would inevitably improve the clinical management of plasma cell disorder patients, and the increased knowledge would ultimately result in better outcomes for the patients.

Cardiovascular involvement in patients affected by multiple myeloma: a comprehensive review of recent advances

INTRODUCTION

Multiple Myeloma (MM) is hematological neoplasia originating from plasma cells, which accounts for almost 1% of all oncologic malignancies. The median age of patients at diagnosis is about 65 years old and over. In this age group, cardiovascular (CV) diseases often co-exist, increasing the risk of adverse events related to MM treatment. A comprehensive search on the main educational platforms was performed and high-quality original articles and reviews were included.

AREAS COVERED

Patients affected by MM are at risk for heart failure, uncontrolled systemic hypertension, accelerated ischemic heart disease, arterial/venous thromboembolism, and arrhythmias. These complications may be due to the effects of chemotherapy on the CV system, which may play on preexisting risk factors, and amyloid deposition at cardiac level.

EXPERT OPINION

This review provides an updated overview of the spectrum of CV diseases that may affect MM patients, highlighting possible treatment strategies according to the latest recommendations. Cooperation between onco-hematologist and cardiologist is crucial in managing this population, in particular for adequate risk assessment, early diagnosis of CV complications, and proper treatment.

Modern markers for evaluating bone disease in multiple myeloma (Review)

Multiple myeloma (MM) is a bone marrow neoplasia with increasing incidence compared to previous years. Although new therapeutic molecules have been introduced, it remains an incurable disease with severe repercussions to patients. For many patients, bone disease represents a severe problem often causing pain, pathological bone fractures, and spinal cord compression, which affects the quality of life. This article analyzes the main markers of bone destruction in MM as well as risk factors for severe bone damage. Bone complications have a negative impact on the quality of life of patients with MM, along with other associated complications (renal failure, hypogammaglobulinemia, osteolytic bone disease, hypercalcemia, anemia). The markers of bone destruction described in this article include: interleukin (IL)-6, tumor necrosis factor (TNF)-α, receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG), amino- and carboxy-terminal cross-linking telopeptide of type I collagen (NTX, CTX), human bone sialoprotein (BSP) and dickkopf-1 secreted glycoprotein (DKK1). The future practical applicability of this literature review would be the large-scale determination of markers of bone destruction that correlate with the negative evolution to complications of bone disease or the implications that these markers have in regards to treatment.

A combination of carfilzomib, dexamethasone, and daratumumab for treatment of adult patients with relapsed/refractory multiple myeloma in two dosing regimens: once-weekly and twice-weekly

INTRODUCTION

Despite the development of new therapeutic agents, relapsed/refractory multiple myeloma (RRMM) is associated with poor survival outcomes. Furthermore, many patients develop resistance to immunomodulatory drugs (IMiD), creating a need for IMiD-free regimens. Areas covered: This review focuses on the combination of carfilzomib, dexamethasone, and daratumumab (KdD or DKd) which has shown promising results in patients with RRMM who have tried multiple lines of therapy, and has been approved in the U.S., EU, and Japan. The KdD triplet has two recommended dosage regimens, carfilzomib once-weekly (KdD70 QW) and carfilzomib twice-weekly (KdD56 BIW), with comparable efficacy and safety profiles. Expert opinion: These options provide flexibility to patients and healthcare providers, especially in the era of COVID-19. Carfilzomib-based regimens remain a standard of care based on multiple randomized phase 3 studies. Additional studies are currently underway investigating carfilzomib-based regimens such as KdD combined with novel agents. Nevertheless, KdD is one of the most efficacious options for patients with RRMM.

Isatuximab: A Review of Its Use in Multiple Myeloma

Isatuximab (Sarclisa®; isatuximab-irfc in the USA) is an anti-CD38 monoclonal antibody (mAb) approved for use in the treatment of adults with multiple myeloma (MM): in combination with pomalidomide and dexamethasone for those with relapsed and refractory MM (RRMM) who have received ≥ 2 prior therapies, including lenalidomide and a proteasome inhibitor; and in combination with carfilzomib and dexamethasone for those with relapsed MM who have received ≥ 1 prior therapy. In phase III studies, the addition of isatuximab to pomalidomide and dexamethasone significantly prolonged progression-free survival (PFS) and improved the depth of tumour response in patients with RRMM, as did the addition of isatuximab to carfilzomib and dexamethasone in patients with relapsed or refractory MM. Health-related quality of life was maintained when isatuximab was combined with these other therapies. Isatuximab-based combination therapies were generally well tolerated and demonstrated a manageable safety profile with no new safety signals. Although mature overall survival data are awaited, available evidence indicates that the combinations of isatuximab with pomalidomide and dexamethasone and isatuximab with carfilzomib and dexamethasone are important additional treatment options for RRMM and relapsed MM, respectively.

Identification of three immune molecular subtypes associated with immune profiles, immune checkpoints, and clinical outcome in multiple myeloma

Purpose

To identify the immune molecular subtype for MM to help achieve individualized and precise targeted therapy.

Methods

The GDC API was used to download the TCGA‐MM profile dataset, which contains 859 samples in total, all of which were anterior to the standard treatment after diagnosis. Moreover, 282, 298, and 258 samples were stage I, stage II, and stage III separately. We used the immune gene expression profile for consistent clustering; and used the R software package ConsensusClusterPlus to sort the immune molecular subtypes. Correlation between subtypes and clinical features, immunity, and prognosis was then analyzed.

Results

A total of 859 tumor samples were separated into these three subtypes, which were not meaningfully related to age or sex but showed a remarkable association with stage. The results suggested that obvious differences in immune metagene expression and expression of 10 immune checkpoint genes appeared among the three subtypes.

Conclusion

The three subtypes are distinctly different in terms of immune metagenes, immune checkpoint molecules, and clinical prognosis. The discovery of the immune microenvironment of MM could further reveal the strategy for immunotherapy in MM and provide a promising candidate prognostic tool for survival.

Stromal Cells Serve Drug Resistance for Multiple Myeloma via Mitochondrial Transfer: A Study on Primary Myeloma and Stromal Cells

Simple Summary

Mitochondrial transfer plays a crucial role in the acquisition of drug resistance in multiple myeloma, but its exact mechanism is not yet clear; moreover, overcoming the drug resistance that it causes is also a major challenge. Our research on primary myeloma cell cultures reveals that mitochondrial transfer is bi-directional between bone marrow stromal cells and myeloma cells, occurring via tunneling nanotubes and partial cell fusion with extreme increases under the influence of chemotherapeutic drugs, whereupon survival and adenosine triphosphate levels increase, while mitochondrial superoxide levels decrease in myeloma cells. These changes and the elevation of superoxide levels in stromal cells are proportional to the amount of incorporated mitochondria derived from the other cell type and to the concentration of the used drug. Although the inhibition of mitochondrial transfer is limited between stromal and myeloma cells, the supportive effect of stromal cells can be effectively averted by influencing the tumor metabolism with an inhibitor of oxidative phosphorylation in addition to chemotherapeutics.

Abstract

Recently, it has become evident that mitochondrial transfer (MT) plays a crucial role in the acquisition of cancer drug resistance in many hematologic malignancies; however, for multiple myeloma, there is a need to generate novel data to better understand this mechanism. Here, we show that primary myeloma cells (MMs) respond to an increasing concentration of chemotherapeutic drugs with an increase in the acquisition of mitochondria from autologous bone marrow stromal cells (BM-MSCs), whereupon survival and adenosine triphosphate levels of MMs increase, while the mitochondrial superoxide levels decrease in MMs. These changes are proportional to the amount of incorporated BM-MSC-derived mitochondria and to the concentration of the used drug, but seem independent from the type and mechanism of action of chemotherapeutics. In parallel, BM-MSCs also incorporate an increasing amount of MM cell-derived mitochondria accompanied by an elevation of superoxide levels. Using the therapeutic antibodies Daratumumab, Isatuximab, or Elotuzumab, no similar effect was observed regarding the MT. Our research shows that MT occurs via tunneling nanotubes and partial cell fusion with extreme increases under the influence of chemotherapeutic drugs, but its inhibition is limited. However, the supportive effect of stromal cells can be effectively avoided by influencing the metabolism of myeloma cells with the concomitant use of chemotherapeutic agents and an inhibitor of oxidative phosphorylation.

Mechanisms of Action of the New Antibodies in Use in Multiple Myeloma

Monoclonal antibodies (mAbs) directed against antigen-specific of multiple myeloma (MM) cells have Fc-dependent immune effector mechanisms, such as complement-dependent cytotoxicity (CDC), antibody-dependent cellular cytotoxicity (ADCC), and antibody-dependent cellular phagocytosis (ADCP), but the choice of the antigen is crucial for the development of effective immuno-therapy in MM. Recently new immunotherapeutic options in MM patients have been developed against different myeloma-related antigens as drug conjugate-antibody, bispecific T-cell engagers (BiTEs) and chimeric antigen receptor (CAR)-T cells. In this review, we will highlight the mechanism of action of immuno-therapy currently available in clinical practice to target CD38, SLAMF7, and BCMA, focusing on the biological role of the targets and on mechanisms of actions of the different immunotherapeutic approaches underlying their advantages and disadvantages with critical review of the literature data.

Balancing the CD38 Expression on Effector and Target Cells in Daratumumab-Mediated NK Cell ADCC against Multiple Myeloma

Simple Summary

We tracked the cytotoxic potential of NK cells towards multiple myeloma cells in daratumumab-mediated antibody-dependent cellular cytotoxicity assays. These cytotoxicity levels could be directly correlated to the expression of the target antigen (CD38) and to the percentage of fratricide between effector cells. Increasing the expression of CD38 on target cells or neutralizing CD38 on effector cells changed the equilibrium between target and effector cell lysis and promoted multiple myeloma cell death. This study highlights the importance of a balanced CD38 expression on target and effector cells and attempts to alter this balance will affect the susceptibility of MM cells towards daratumumab-mediated cellular toxicity.

Abstract

Multiple myeloma (MM) is an incurable cancer characterized by the proliferation and accumulation of monoclonal plasma cells in the bone marrow. The monoclonal anti-CD38 daratumumab has taken a central place in the different treatment regimens for newly diagnosed and relapsed, refractory myeloma. In this study, we correlated the NK cell-mediated antibody-dependent cellular cytotoxicity (ADCC) and potential fratricide induced by daratumumab with CD38-expression levels on both effector and target cells. We show that CD38 expression can be modulated by adding all-trans retinoic acid (ATRA) or interferon-α to MM cells to further fine-tune these effects. In addition, we observed that ADCC becomes inefficient when fratricide occurs and both ADCC and fratricide depend on the balance between CD38 expression on effector and target cells. However, the addition of adjuvants (retinoic acid or interferon-α) to myeloma cells or the inhibition of fratricide using a CD38-blocking nanobody on NK-cells can reverse this balance towards ADCC and thus promote lysis of target cells by ADCC. ATRA and interferon-α increased the CD38 expression at the surface of MM cells about three-fold and two-fold, respectively. This increase was of interest for MM cells with low CD38 expression, that became susceptible to daratumumab-mediated ADCC after preincubation. A CD38-blocking nanobody prevented the binding of daratumumab to these NK-cells and blunted the fratricidal effect on effector NK cells. In conclusion, our study highlights the importance of a balanced CD38 expression on target and effector cells and attempts to alter this balance will affect the susceptibility of MM cells towards daratumumab-mediated ADCC.

Drug and Solute Transporters in Mediating Resistance to Novel Therapeutics in Multiple Myeloma

Multiple myeloma remains an incurable malignancy of plasma cells. Novel therapies, notably proteasome inhibitors and immunomodulatory drugs, have improved the survival of multiple myeloma patients; however, patients either present with, or develop resistance to, these therapies. Resistance to traditional chemotherapeutic agents can be caused by cellular drug efflux via adenosine triphosphate (ATP)-binding cassette (ABC) transporters, but it is still not clear whether these transporters mediate resistance to proteasome inhibitors and immunomodulatory drugs in multiple myeloma. Solute carrier (SLC) transporters also play a role in cancer drug resistance due to changes in cell homeostasis caused by their abnormal expression and changes in the solutes they transport. In this review, we evaluate resistance to novel therapies used to treat multiple myeloma, as mediated by drug and solute transporters.

Improved therapeutic efficacy of unmodified anti-tumor antibodies by immune checkpoint blockade and kinase targeted therapy in mouse models of melanoma

The use of specific anti-tumor antibodies has transformed the solid cancer therapeutics landscape with the relative successes of therapies such as anti-HER2 in breast cancer, and anti-EGFR in HNSCC and colorectal cancer. However, these therapies result in toxicity and the emergence of resistant tumors. Here, we showed that removing immune suppression and enhancing stimulatory signals increased the anti-tumor activity of unmodified TA99 antibodies (anti-TYRP1) with a significant reduction of growth of solid tumors and lung metastases in mouse models of melanoma. Immune checkpoint blockade enhanced the efficacy of TA99, which was associated with greater CD8⁺/Foxp3⁺, NK1.1⁺ and dendritic cell infiltrates, suggestive of an increased anti-tumor innate and adaptive immune responses. Further, MEK inhibition in melanoma cell lines increased the expression of melanosomal antigens in vitro, and combining TA99 and MEKi in vivo resulted in enhanced tumor control. Moreover, we found an improved therapeutic effect when YUMM tumor-bearing mice were treated with TA99 combined with MEKi and immune checkpoint blockade (anti-PD1 and anti-CTLA4). Our findings suggest that MEKi induced an increased expression of tumor-associated antigens, which in combination with anti-tumor antibodies, generated a robust adaptive anti-tumor response that was sustained by immune checkpoint inhibition therapy. We postulate that combining anti-tumor antibodies with standard-of-care strategies such as immune checkpoint blockade or targeted therapy, will improve therapeutic outcomes in cancer.

Daratumumab and Nanobody-Based Heavy Chain Antibodies Inhibit the ADPR Cyclase but not the NAD+ Hydrolase Activity of CD38-Expressing Multiple Myeloma Cells

Simple Summary

Multiple myeloma is a hematological malignancy of antibody-producing plasma cells in the bone marrow. Nucleotides released from cells in the tumor microenvironment act as inflammatory danger signals. CD38 and other enzymes on the surface of cancer cells hydrolyze these nucleotides to immunosuppressive mediators, thereby hampering anti-tumor immune responses. Daratumumab and other CD38-specific antibodies mediate killing of tumor cells by natural killer cells, macrophages, and the complement system. Here, we investigated whether CD38-specific antibodies also inhibit the enzyme activity of CD38-expressing tumor cells, thereby providing a potential second mode of action. Our results showed that daratumumab and nanobody-based heavy chain antibodies inhibit the ADPR cyclase but not the NAD⁺ hydrolase activity of CD38. Thus, there remains a need for better CD38-inhibitory antibodies.

Abstract

The nucleotides ATP and NAD⁺ are released from stressed cells as endogenous danger signals. Ecto-enzymes in the tumor microenvironment hydrolyze these inflammatory nucleotides to immunosuppressive adenosine, thereby, hampering anti-tumor immune responses. The NAD⁺ hydrolase CD38 is expressed at high levels on the cell surface of multiple myeloma (MM) cells. Daratumumab, a CD38-specific monoclonal antibody promotes cytotoxicity against MM cells. With long CDR3 loops, nanobodies and nanobody-based heavy chain antibodies (hcAbs) might bind to cavities on CD38 and thereby inhibit its enzyme activity more potently than conventional antibodies. The goal of our study was to establish assays for monitoring the enzymatic activities of CD38 on the cell surface of tumor cells and to assess the effects of CD38-specific antibodies on these activities. We monitored the enzymatic activity of CD38-expressing MM and other tumor cell lines, using fluorometric and HPLC assays. Our results showed that daratumumab and hcAb MU1067 inhibit the ADPR cyclase but not the NAD⁺ hydrolase activity of CD38-expressing MM cells. We conclude that neither clinically approved daratumumab nor recently developed nanobody-derived hcAbs provide a second mode of action against MM cells. Thus, there remains a quest for “double action” CD38-inhibitory antibodies.

The role of belantamab mafodotin for patients with relapsed and/or refractory multiple myeloma

Belantamab mafodotin (belamaf) is a first-in-class anti-B-cell maturation antigen (BCMA) antibody-drug conjugate (ADC) that recently gained regulatory approval for the treatment of relapsed and/or refractory multiple myeloma (RRMM) patients who have received at least four prior therapies including an anti-CD38 monoclonal antibody (mAb), a proteasome inhibitor (PI), and an immunomodulatory drug (IMiD). As the first BCMA-targeted therapy to be approved in multiple myeloma along with its "off-the-shelf" outpatient administration, belamaf addresses a significant unmet need in RRMM that is refractory to IMiD, PI, and anti-CD38 mAb therapy, otherwise known as triple-class refractory myeloma. Belamaf is also associated with frequent corneal ocular adverse events, which represents a unique toxicity in multiple myeloma therapeutics, and its administration requires a multidisciplinary approach with oncologists and eye care specialists to safely and effectively manage patients on belamaf therapy. In this review, we discuss the preclinical and clinical data leading to the regulatory approval of belamaf, the monitoring and mitigation strategies of corneal ocular adverse events, and its current and future role in the RRMM treatment landscape.

Evaluating the Relationship of GDF-15 with Clinical Characteristics, Cardinal Features, and Survival in Multiple Myeloma

Growth differentiation factor 15 (GDF-15), a member of the transforming growth factor-β superfamily, participates in processes associated with myeloma development and its end-organ complications. It plays a significant role in both physiological and abnormal erythropoiesis and regulates iron homeostasis through modulation of hepcidin. It is abnormally secreted in marrow stromal cells of patients with multiple myeloma (MM), which may reflect the tumor microenvironment. We analyzed the associations of serum GDF-15 with clinical characteristics of 73 MM patients (including asymptomatic MM) and the laboratory indices of renal function, anemia, and inflammation. Baseline serum GDF-15 was studied as the predictor of two-year survival. We defined five clinically relevant subgroups of patients (symptomatic MM only, patients with and without remission, patients on chemotherapy, and without treatment). Increased GDF-15 concentrations were associated with more advanced MM stage, anemia, renal impairment (lower glomerular filtration and higher markers of tubular injury), and inflammation. Most of the results were confirmed in the subgroup analysis. Serum cystatin C and urine neutrophil gelatinase-associated lipocalin were associated with GDF-15 independently of other variables. In the studied MM patients, GDF-15 did not significantly predict survival (p = 0.06). Our results suggest that serum GDF-15 reflects myeloma burden and shares a relationship with several markers of prognostic significance, as well as major manifestations.

How Does Complement Affect Hematological Malignancies: From Basic Mechanisms to Clinical Application

Complement, as a central immune surveillance system, can be activated within seconds upon stimulation, thereby displaying multiple immune effector functions. However, in pathologic scenarios (like in tumor progression), activated complement can both display protective effects to control tumor development and passively promotes the tumor growth. Clinical investigations show that patients with several hematological malignancies often display abnormal level of specific complement components, which in turn modulates complement activation or deregulated cascade. In the past decades, complement-dependent cytotoxicity and complement-dependent cell-mediated phagocytosis were fully approved to display vital roles in monoclonal antibody-based immunotherapies, especially in therapies against hematological malignancies. However, tumor-mediated complement evasion presents a big challenge for such a therapy. This review aims to provide an integrative overview on the roles of the complement in tumor promotion, highlights complement mediated effects on antibody-based immunotherapy against distinct hematological tumors, hopefully provides a theoretical basis for the development of complement-based cancer targeted therapies.

Designing high affinity target-binding peptides to HLA-E: a key membrane antigen of multiple myeloma

Multiple myeloma (MM) is a plasma cell malignancy that is currently incurable. Finding new targets and designing drugs are crucial for the treatment of MM. The two datasets (GSE6691 and GSE39754) are used to screen highly expressed antigen on MM cells. HLA-E was an ideal target for it was a hub gene, and also located in one of the key clusters. Highly expression of HLA-E mRNA on MM cells was also confirmed by real-time qPCR testing the MM patients' samples in Shengjing hospital. Crystal structure of HLA-E was obtained from Protein Data Bank (PDB ID: 3CDG) which was used to design targeting peptides with Molecular Operating Environment software. By analyzing interaction between CD94/NKG2A and HLA-E, a peptide with twelve amino acids was screened as a model peptide. Peptides library was constructed by randomly replaced non-key amino acid. Peptide-protein docking method was used to identify high affinity peptides. PEPTIDE 1-3 and model peptide were synthesized and identified the affinity to HLA-E by flow cytometer and confocal laser microscopy. At last, PEPTIDE3 (NALDEYCEDKNR) was found with the highest affinity. Taking all, HLA-E is a new treatment target, and PEPTIDE 3 is an ideal high affinity target-binding peptide candidate.

Characteristics of a Novel Target Antigen Against Myeloma Cells for Immunotherapy

Despite the availability of therapeutic treatments, multiple myeloma is an incurable haematological disorder. In this study, we aimed to clarify the role of CXorf48 as a therapeutic target in multiple myeloma. Based on a previously identified HLA-A*24:02-restiricted epitope from this novel cancer/testis antigen, we characterized the activities of cytotoxic T lymphocytes (CTLs) specific to this antigen against myeloma cells and evaluated the effects of demethylating agents in increasing antigen expression and enhancing the cytotoxic activity of CTLs. CXorf48 expression was examined by reverse transcription polymerase chain reaction (RT-PCR) using nine myeloma cell lines. Cell lines with low CXorf48 expression were treated by demethylating agents (DMAs), 5-azacytidine (5-aza), and 5-aza-2’-deoxycytidine (DAC) to evaluate gene expression using quantitative RT-PCR. Furthermore, CXorf48-specific CTLs were induced from peripheral blood mononuclear cells of HLA-A*24:02-positive healthy donors to evaluate antigen recognition using ELISpot and ⁵¹Cr cytotoxicity assays. CXorf48 was widely expressed in myeloma cells, and gene expression was significantly increased by DMAs. Furthermore, CXorf48-specific CTLs recognized DMA-treated myeloma cells. These findings suggest that CXorf48 is a useful target for immunotherapy, such as vaccination, in combination with demethylating agents for the treatment of patients with myeloma.

CD38: targeted therapy in multiple myeloma and therapeutic potential for solid cancers

INTRODUCTION

CD38 is expressed by some cells of hematological malignancies and tumor-related immunosuppressive cells, including regulatory T cells, regulatory B cells, and myeloid-derived suppressor cells. CD38 is an effective target in some hematological malignancies such as multiple myeloma (MM). Daratumumab (Dara), a CD38-targeting antibody, can eliminate CD38^high immune suppressor cells and is regarded as a standard therapy for MM because of its outstanding clinical efficacy. Other CD38 monospecific antibodies, such as isatuximab, MOR202, and TAK079, showed promising effects in clinical trials.

AREA COVERED

This review examines the expression, function, and targeting of CD38 in MM and its potential to deplete immunosuppressive cells in solid cancers. We summarize the distribution and biological function of CD38 and discuss the application of anti-CD38 drugs in hematological malignancies. We also analyz the role of CD38⁺ immune cells in the tumor microenvironment to encourage additional investigations that target CD38 in solid cancers. PubMed and ClinicalTrials were searched to identify relevant literature from the database inception to 30 April 2020.

EXPERT OPINION

There is convincing evidence that CD38-targeted immunotherapeutics reduce CD38⁺ immune suppressor cells. This result suggests that CD38 can be exploited to treat solid tumors by regulating the immunosuppressive microenvironment.

Novel Approaches to Improve Myeloma Cell Killing by Monoclonal Antibodies

The monoclonal antibodies (mAbs) have significantly changed the treatment of multiple myeloma (MM) patients. However, despite their introduction, MM remains an incurable disease. The mAbs currently used for MM treatment were developed with different mechanisms of action able to target antigens, such as cluster of differentiation 38 (CD38) and SLAM family member 7 (SLAMF7) expressed by both, MM cells and the immune microenvironment cells. In this review, we focused on the mechanisms of action of the main mAbs approved for the therapy of MM, and on the possible novel approaches to improve MM cell killing by mAbs. Actually, the combination of anti-CD38 or anti-SLAMF7 mAbs with the immunomodulatory drugs significantly improved the clinical effect in MM patients. On the other hand, pre-clinical evidence indicates that different approaches may increase the efficacy of mAbs. The use of trans-retinoic acid, the cyclophosphamide or the combination of anti-CD47 and anti-CD137 mAbs have given the rationale to design these types of combinations therapies in MM patients in the future. In conclusion, a better understanding of the mechanism of action of the mAbs will allow us to develop novel therapeutic approaches to improve their response rate and to overcome their resistance in MM patients.

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.

PCAT-1 promotes cell growth by sponging miR-129 via MAP3K7/NF-κB pathway in multiple myeloma

Loss of one or some specific miRNA-mediated regulation is closely associated with malignant progression of multiple myeloma (MM). But how these miRNAs work and what role the specific miRNA plays in this process of malignant progression remain unclear. It was found in this study that the expression of miR-129 was decreased in both MM cell lines and newly diagnosed MM patients. Further clinicopathological statistics showed that miR-129 was correlated with the isotype of MM patients. MiR-129 overexpression disturbed cell proliferation, cell cycle evolution and spurred apoptosis both in vitro and in vivo. MAP3K7, a kinase able to activate NF-κB circuit, was found to be up-regulated in MM and contain a binding target of miR-129. In addition, lncRNA PCAT-1 functioned to sponge miR-129 and thereby lowered its expression. PCAT-1 knockdown eliminated the tumour-promoting effect caused by miR-129 inhibition, probably through repressing MAP3K7 and subsequent NF-κB activation. To the best of our knowledge, this is the first study to have discovered that increased expression of PCAT-1 could augment cell proliferation and cycle procession and inhibit apoptosis by down-regulating miR-129 via the MAP3K7/NF-κB pathway in MM.

Bone Marrow Stromal Cells-Induced Drug Resistance in Multiple Myeloma

Multiple myeloma is a B-cell lineage cancer in which neoplastic plasma cells expand in the bone marrow and pathophysiological interactions with components of microenvironment influence many biological aspects of the malignant phenotype, including apoptosis, survival, proliferation, and invasion. Despite the therapeutic progress achieved in the last two decades with the introduction of a more effective and safe new class of drugs (i.e., immunomodulators, proteasome inhibitors, monoclonal antibodies), there is improvement in patient survival, and multiple myeloma (MM) remains a non-curable disease. The bone marrow microenvironment is a complex structure composed of cells, extracellular matrix (ECM) proteins, and cytokines, in which tumor plasma cells home and expand. The role of the bone marrow (BM) microenvironment is fundamental during MM disease progression because modification induced by tumor plasma cells is crucial for composing a "permissive" environment that supports MM plasma cells proliferation, migration, survival, and drug resistance. The "activated phenotype" of the microenvironment of multiple myeloma is functional to plasma cell proliferation and spreading and to plasma cell drug resistance. Plasma cell drug resistance induced by bone marrow stromal cells is mediated by stress-managing pathways, autophagy, transcriptional rewiring, and non-coding RNAs dysregulation. These processes represent novel targets for the ever-increasing anti-MM therapeutic armamentarium.

A novel approach to remove interference of therapeutic monoclonal antibody with serum protein electrophoresis

OBJECTIVES

Multiple myeloma (MM) is characterized by malignant growth of plasma cells, usually producing a monoclonal antibody (mAb). New treatments for MM include therapeutic monoclonal antibodies (tmAbs), but patients treated with tmAb demonstrate interference on serum electrophoresis (SPE) and immunoprecipitation electrophoresis (IEP). Evaluation of treatment efficacy and determination of MM remission include SPE and IEP which identifies mAb, but cannot differentiate between disease associated mAb and tmAb. We hypothesized that tmAb could be removed from patient sera before testing by SPE and IEP to provide accurate diagnoses for clinicians.

DESIGN AND METHODS

We developed the Antigen Specific therapeutic monoclonal Antibody Depletion Assay (ASADA), that utilizes magnetic beads coated with the cognate antigen of the tmAbs, to deplete two different tmAb (daratumumab, elotuzumab) from saline and patient sera and assessed for complete removal of tmAb by SPE and IEP.

RESULTS

We found that tmAb could be efficiently removed from saline and patient sera. ASADA demonstrated acceptable analytical specificity and sensitivity in IEP. Recovery of appropriate quantitative values by SPE was demonstrated with clinically acceptable precision. A single bead cocktail could be used to treat both daratumumab and elotuzumab.

CONCLUSIONS

This demonstrates proof of principle that ASADA can be used to remove current and future tmAb from patient sera, regardless of platform. This research provides for accurate diagnosis, disease monitoring, and remission status in MM patients being treated with tmAb.

Isatuximab plus pomalidomide and low-dose dexamethasone versus pomalidomide and low-dose dexamethasone in patients with relapsed and refractory multiple myeloma (ICARIA-MM): a randomised, multicentre, open-label, phase 3 study

BACKGROUND

Isatuximab is a monoclonal antibody that binds a specific epitope on the human CD38 receptor and has antitumour activity via multiple mechanisms of action. In a previous phase 1b study, around 65% of patients with relapsed and refractory multiple myeloma achieved an overall response with a combination of isatuximab with pomalidomide and low-dose dexamethasone. The aim of this study was to determine the progression-free survival benefit of isatuximab plus pomalidomide and dexamethasone compared with pomalidomide and dexamethasone in patients with relapsed and refractory multiple myeloma.

METHODS

We did a randomised, multicentre, open-label, phase 3 study at 102 hospitals in 24 countries in Europe, North America, and the Asia-Pacific regions. Eligible participants were adult patients with relapsed and refractory multiple myeloma who had received at least two previous lines of treatment, including lenalidomide and a proteasome inhibitor. Patients were excluded if they were refractory to previous treatment with an anti-CD38 monoclonal antibody. We randomly assigned patients (1:1) to either isatuximab 10 mg/kg plus pomalidomide 4 mg plus dexamethasone 40 mg (20 mg for patients aged ≥75 years), or pomalidomide 4 mg plus dexamethasone 40 mg. Randomisation was done using interactive response technology and stratified according to the number of previous lines of treatment (2-3 vs >3) and age (<75 years vs ≥75 years). Treatments were assigned based on a permuted blocked randomisation scheme with a block size of four. The isatuximab-pomalidomide-dexamethasone group received isatuximab intravenously on days 1, 8, 15, and 22 in the first 28-day cycle, then on days 1 and 15 in subsequent cycles. Both groups received oral pomalidomide on days 1 to 21 in each cycle, and oral or intravenous dexamethasone on days 1, 8, 15, and 22 of each cycle. Treatment continued until disease progression, unacceptable toxicity, or consent withdrawal. Dose reductions for adverse reactions were permitted for pomalidomide and dexamethasone, but not for isatuximab. The primary endpoint was progression-free survival, determined by an independent response committee and assessed in the intention-to-treat population. Safety was assessed in all participants who received at least one dose of study drug. This study is registered at ClinicalTrials.gov, number NCT02990338.

FINDINGS

Between Jan 10, 2017, and Feb 2, 2018, we randomly assigned 307 patients to treatment: 154 to isatuximab-pomalidomide-dexamethasone, and 153 to pomalidomide-dexamethasone. At a median follow-up of 11·6 months (IQR 10·1-13·9), median progression-free survival was 11·5 months (95% CI 8·9-13·9) in the isatuximab-pomalidomide-dexamethasone group versus 6·5 months (4·5-8·3) in the pomalidomide-dexamethasone group; hazard ratio 0·596, 95% CI 0·44-0·81; p=0·001 by stratified log-rank test. The most frequent treatment-emergent adverse events (any grade; isatuximab-pomalidomide-dexamethasone vs pomalidomide-dexamethasone) were infusion reactions (56 [38%] vs 0), upper respiratory tract infections (43 [28%] vs 26 [17%]), and diarrhoea (39 [26%] vs 29 [20%]). Adverse events with a fatal outcome were reported in 12 patients (8%) in the isatuximab-pomalidomide-dexamethasone group and 14 (9%) in the pomalidomide-dexamethasone group. Deaths due to treatment-related adverse events were reported for one patient (<1%) in the isatuximab-pomalidomide-dexamethasone group (sepsis) and two (1%) in the pomalidomide-dexamethasone group (pneumonia and urinary tract infection).

INTERPRETATION

The addition of isatuximab to pomalidomide-dexamethasone significantly improves progression-free survival in patients with relapsed and refractory multiple myeloma. Isatuximab is an important new treatment option for the management of relapsed and refractory myeloma, particularly for patients who become refractory to lenalidomide and a proteasome inhibitor.

FUNDING

Sanofi. VIDEO ABSTRACT.

CD38, a Receptor with Multifunctional Activities: From Modulatory Functions on Regulatory Cell Subsets and Extracellular Vesicles, to a Target for Therapeutic Strategies

CD38 is a multifunctional cell surface protein endowed with receptor/enzymatic functions. The protein is generally expressed at low/intermediate levels on hematological tissues and some solid tumors, scoring the highest levels on plasma cells (PC) and PC-derived neoplasia. CD38 was originally described as a receptor expressed by activated cells, mainly T lymphocytes, wherein it also regulates cell adhesion and cooperates in signal transduction mediated by major receptor complexes. Furthermore, CD38 metabolizes extracellular NAD+, generating ADPR and cyclic ADPR. This ecto-enzyme controls extra-cellular nucleotide homeostasis and intra-cellular calcium fluxes, stressing its relevance in multiple physiopathological conditions (infection, tumorigenesis and aging). In clinics, CD38 was adopted as a cell activation marker and in the diagnostic/staging of leukemias. Quantitative surface CD38 expression by multiple myeloma (MM) cells was the basic criterion used for therapeutic application of anti-CD38 monoclonal antibodies (mAbs). Anti-CD38 mAbs-mediated PC depletion in autoimmunity and organ transplants is currently under investigation. This review analyzes different aspects of CD38's role in regulatory cell populations and how these effects are obtained. Characterizing CD38 functional properties may widen the extension of therapeutic applications for anti-CD38 mAbs. The availability of therapeutic mAbs with different effects on CD38 enzymatic functions may be rapidly translated to immunotherapeutic strategies of cell immune defense.

Therapeutic Opportunities with Pharmacological Inhibition of CD38 with Isatuximab

CD38 is a transmembrane glycoprotein with ectoenzymatic activity involved in regulation of migration, signal transduction, and receptor-mediated adhesion. CD38 is highly expressed on various malignant cells, including multiple myeloma (MM), and at relatively low levels in other tissues, making it a suitable target for therapeutic antibodies. Several anti-CD38 therapies have been, or are being, developed for the treatment of MM, including daratumumab and isatuximab (SAR650984), respectively. Studies have shown that anti-CD38 therapies are effective in the treatment of relapsed/refractory MM and are well tolerated, with infusion reactions being the most common side effects. They can be used as monotherapy or in combination with immunomodulatory agents, such as pomalidomide, or proteasome inhibitors to potentiate their activity. Here we examine isatuximab and several anti-CD38 agents in development that were generated using new antibody engineering techniques and that may lead to more effective CD38 targeting. We also summarize trials assessing these antibodies in MM, other malignancies, and solid organ transplantation. Finally, we propose that further research on the mechanisms of resistance to anti-CD38 therapy and the development of biomarkers and new backbone regimens with CD38 antibodies will be important steps in building more personalized treatment for patients with MM.

Monoclonal Antibody Therapies in Multiple Myeloma: A Challenge to Develop Novel Targets

The treatment options in multiple myeloma (MM) has changed dramatically over the past decade with the development of novel agents such as proteasome inhibitors (PIs); bortezomib and immunomodulatory drugs (IMiDs); thalidomide, and lenalidomide which revealed high efficacy and improvement of overall survival (OS) in MM patients. However, despite these progresses, most patients relapse and become eventually refractory to these therapies. Thus, the development of novel, targeted immunotherapies has been pursued aggressively. Recently, next-generation PIs; carfilzomib and ixazomib, IMiD; pomalidomide, histone deacetylase inhibitor (HDADi); panobinostat and monoclonal antibodies (MoAbs); and elotuzumab and daratumumab have emerged, and especially, combination of mAbs plus novel agents has led to dramatic improvements in the outcome of MM patients. The field of immune therapies has been accelerating in the treatment of hematological malignancies and has also taken center stage in MM. This review focuses on an overview of current status of novel MoAb therapy including bispecific T-cell engager (BiTE) antibody (BsAb), antibody-drug conjugate (ADC), and chimeric antigen receptor (CAR) T cells, in relapsed or refractory MM (RRMM). Lastly, investigational novel MoAb-based therapy to overcome immunotherapy resistance in MM is shown.

An Anti-BCMA RNA Aptamer for miRNA Intracellular Delivery

B cell maturation antigen is highly expressed on malignant plasma cells in human multiple myeloma and has recently emerged as a very promising target for therapeutic interventions. Nucleic-acid-based aptamers are small oligonucleotides with high selective targeting properties and functional advantages over monoclonal antibodies, as both diagnostic and therapeutic tools. Here, we describe the generation of the first-ever-described nuclease resistant RNA aptamer selectively binding to B cell maturation antigen. We adopted a modified cell-based systematic evolution of ligands by exponential enrichment approach allowing the enrichment for internalizing aptamers. The selected 2′Fluoro-Pyrimidine modified aptamer, named apt69.T, effectively and selectively bound B cell maturation antigen-expressing myeloma cells with rapid and efficient internalization. Interestingly, apt69.T inhibited APRIL-dependent nuclear factor κB (NF-κB) pathway in vitro. Moreover, the aptamer was conjugated to microRNA-137 (miR-137) and anti-miR-222, demonstrating high potential against tumor cells. In conclusion, apt69.T is a novel tool suitable for direct targeting and delivery of therapeutics to B cell maturation antigen-expressing myeloma cells.

Multiple Myeloma: What Do We Do About Immunodeficiency?

Multiple myeloma (MM) is an incurable hematological malignancy. Immunodeficiency results in the incapability of immunity to eradicate both tumor cells and pathogens. Immunotherapies along with antibiotics and other anti-infectious agents are applied as substitutes for immunity in MM. Immunotherapies including monoclonal antibodies, immune checkpoints inhibitors, affinity- enhanced T cells, chimeric antigen receptor T cells and dendritic cell vaccines are revolutionizing MM treatment. By suppressing the pro-inflammatory milieu and pathogens, prophylactic and therapeutic antibiotics represent anti-tumor and anti-infection properties. It is expected that deeper understanding of infection, immunity and tumor physio-pathologies in MM will accelerate the optimization of combined therapies, thus improving prognosis in MM.