Monoclonal antibodies in the treatment of multiple myeloma: current status and future perspectives

A comprehensive review of the PTEN/PI3K/Akt axis in multiple myeloma: From molecular interactions to potential therapeutic targets

Phosphatase and tensin homolog (PTEN), phosphatidylinositol 3-kinase (PI3K), and protein kinase B (Akt) signaling pathways contribute to the development of several cancers, including multiple myeloma (MM). PTEN is a tumor suppressor that influences the PI3K/Akt/mTOR pathway, which in turn impacts vital cellular processes like growth, survival, and treatment resistance. The current study aims to present the role of PTEN and PI3K/Akt/mTOR signaling in the development of MM and its response to treatment. In addition, the molecular interactions in MM that underpin the PI3K/Akt/mTOR pathway and address potential implications for the development of successful treatment plans are also discussed in detail. We investigate their relationship to both upstream and downstream regulators, highlighting new developments in combined therapies that target the PTEN/PI3K/Akt axis to overcome drug resistance, including the use of PI3K and mitogen-activated protein kinase (MAPK) inhibitors. We also emphasize that PTEN/PI3K/Akt pathway elements may be used in MM diagnosis, prognosis, and therapeutic targets.

The role of minimal residual disease and serum free light chain ratio in the management of multiple myeloma

Multiple myeloma (MM) denotes a cancerous growth characterized by abnormal proliferation of plasma cells. Growing evidence suggests that the complexity in addressing MM lies in the presence of minimal residual disease (MRD) within the body. MRD assessment is becoming increasingly important for risk assessment in patients with MM. Similarly, the levels of serum free protein light chain and their ratio play a crucial role in assessing the disease burden and changes in MM. In this paper, we review and explore the utilization of MRD and serum free light chain ratio in the treatment of MM, delving into their respective characteristics, advantages, disadvantages, and their interrelation.

Regulation of Treg cells by cytokine signaling and co-stimulatory molecules

CD4+CD25+Foxp3+ regulatory T cells (Tregs), a vital component of the immune system, are responsible for maintaining immune homeostasis and preventing excessive immune responses. This review explores the signaling pathways of the cytokines that regulate Treg cells, including transforming growth factor beta (TGF-β), interleukin (IL)-2, IL-10, and IL-35, which foster the differentiation and enhance the immunosuppressive capabilities of Tregs. It also examines how, conversely, signals mediated by IL-6 and tumor necrosis factor -alpha (TNF-α) can undermine Treg suppressive functions or even drive their reprogramming into effector T cells. The B7 family comprises indispensable co-stimulators for T cell activation. Among its members, this review focuses on the capacity of CTLA-4 and PD-1 to regulate the differentiation, function, and survival of Tregs. As Tregs play an essential role in maintaining immune homeostasis, their dysfunction contributes to the pathogenesis of autoimmune diseases. This review delves into the potential of employing Treg-based immunotherapy for the treatment of autoimmune diseases, transplant rejection, and cancer. By shedding light on these topics, this article aims to enhance our understanding of the regulation of Tregs by cytokines and their therapeutic potential for various pathological conditions.

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.

Eastern Cooperative Oncology Group, 2-microglobulin, hemoglobin, and lactate dehydrogenase can predict early grade ≥ 3 infection in patients with newly diagnosed multiple myeloma: A real-world multicenter study

Introduction

This research explored the clinical application of grade ≥ 3 infection predictive models for the newly diagnosed multiple myeloma (NDMM) population.

Methods

It evaluated 306 patients with NDMM based on three different predictive models. The relationship between the grade ≥ 3 infection rates in NDMM and the scores was analyzed retrospectively. The cumulative incidence of early grade ≥ 3 infection was estimated using the Kaplan-Meier method and log-rank test to assess the statistical significance of the difference. To compare the predictive performance in the prediction of infection, the Receiver Operating Characteristic Curve (ROC) curve was used to show the area under the curve (AUC), and DeLong's test was used to analyze the difference in AUC.

Results

The incidence of grade ≥ 3 infection within the first 4 months of NDMM was 40.20%. Concerning the FIRST score (predictors: ECOG, β2-microglobulin, hemoglobin, and lactate dehydrogenase), GEM-PETHEMA score (predictors: albumin, male sex, ECOG, and non-IgA type MM), and Infection Risk model of Multiple Myeloma (IRMM) score (predictors: ECOG, serum β2-microglobulin, globulin, and hemoglobin), the probability of early grade ≥ 3 infection in the different groups showed statistically significant differences (low-risk vs. high-risk: 25.81% vs. 50.00%, p < 0.001; low-risk vs. moderate-risk vs. high-risk: 35.93% vs. 41.28% vs. 60.00%, p= 0.045; low-risk vs. moderate-risk vs. high-risk: 20.00% vs. 43.75% vs. 52.04%, p < 0.001). Statistical differences existed in the probability of early grade ≥ 3 infection among the different groups by the FIRST and IRMM scores but no statistical differences in the GEM-PETHEMA score (p < 0.001, p< 0.001, and p = 0.090, respectively). The FIRST score showed good discrimination and simple calculation with highest AUC. Further subgroup analysis showed that the FIRST score could still apply for patients treated with bortezomib-based regimen and frail patients.

Discussion

Our findings indicate that the FIRST score (consisting of ECOG, β2-microglobulin, hemoglobin, and lactate dehydrogenase) is a simple and robust infection stratification tool for patients with NDMM and could be used in routine clinical work.

Disease-driven engineering of peptide-targeted DM1 loaded liposomal nanoparticles for enhanced efficacy in treating multiple myeloma by exploring DM1 prodrug chemistry

Here, we report a CD138 receptor targeting liposomal formulation (TNP[Prodrug-4]) that achieved efficacious tumor growth inhibition in treating multiple myeloma by overcoming the dose limiting severe toxicity issues of a highly potent drug, Mertansine (DM1). Despite the promising potential to treat various cancers, due to poor solubility and pharmacokinetic profile, DM1's translation to the clinic has been unsatisfactory. We hypothesized that the optimal prodrug chemistry would promote efficient loading of the prodrug into targeted nanoparticles and achieve controlled release following endocytosis by the cancer cells, consequently, accomplish the most potent tumor growth inhibition. We evaluated four functional linker chemistries for synthesizing DM1-Prodrug molecules and evaluated their stability and cancer cell toxicity in vitro. It was determined that the phosphodiester moiety, as part of nanoparticle formulations, demonstrated most favorable characteristics with an IC₅₀ of ∼16 nM. Nanoparticle formulations of Prodrug-4 enabled its administration at 8-fold higher dosage of equivalent free drug while remaining below maximum tolerated dose. Importantly, TNP[Prodrug-4] achieved near complete inhibition of tumor growth (∼99% by day 10) compared to control, without displaying noticeable systemic toxicity. TNP[Prodrug-4] promises a formulation that could potentially make DM1 treatment available for wider clinical applications with a long-term goal for better patient outcomes.

Detection of Plasma Cell Disorders by Mass Spectrometry: A Comprehensive Review of 19,523 Cases

OBJECTIVES

To verify the analytical performance of a new mass spectrometry-based method, termed MASS-FIX, when screening for plasma cell disorders in a routine clinical laboratory.

PATIENTS AND METHODS

Results from 19,523 unique patients tested for an M-protein between July 24, 2018, and March 6, 2020, by a combination serum protein electrophoresis (SPEP) and MASS-FIX were examined for consistency with pretest implementation performance. MASS-FIX's ability to verify abnormal results from SPEP and free light chain measurements was then compared with that of immunofixation electrophoresis (IFE) using a separate cohort of 52,586 patients tested by SPEP/IFE during the same period.

RESULTS

Overall, 62.4% of our cohort was negative for an M-protein. Importantly, 7.3% of all specimens had an M spike on SPEP (0.1 to 8.5 g/dL) and MASS-FIX detected an M-protein in all these samples. Of all samples, 30.3% had M-proteins that were detected by MASS-FIX but the SPEP finding was too small for quantification. Of the positive samples, 5.7% contained a therapeutic monoclonal antibody. Of the positive samples, 4.1% had an N-glycosylated light chain (biomarker of high-risk plasma cell disorders). MASS-FIX confirmed a higher percentage of SPEP abnormalities than IFE. MASS-FIX was slightly more sensitive than IFE when confirming an M-protein in samples with an abnormal free light chain ratio. MASS-FIX had a very low sample repeat rate (1.5%). MASS-FIX was highly automatable resulting in a higher number of samples/technologist/day than IFE (∼30% more).

CONCLUSION

Overall, MASS-FIX was successful in maintaining validation characteristics. MASS-FIX was more sensitive in confirming SPEP abnormalities when compared with IFE. Ability to detect therapeutic monoclonal antibodies and glycosylated light chains was distinctly advantageous.

Cyclophosphamide addition to pomalidomide/dexamethasone is not necessarily associated with universal benefits in RRMM

In the backdrop of rapidly changing relapsed/refractory (RR) multiple myeloma (MM) treatment schema that mainly evolves around immunotherapies, it is easy to disregard more traditional drugs. Finding the best partner for pomalidomide, a potent third-generation immunomodulatory drug, is an important agenda we face as a community and cyclophosphamide addition has been used for outcomes augmentation. We carried out this real-world study to identify patients who will show durable response to pomalidomide and those who will benefit from cyclophosphamide addition. A total of 103 patients (57 in pomalidomide-dexamethasone [Pd] group versus 46 in pomalidomide-cyclophosphamide-dexamethasone [PCd]) were studied. They were previously treated with bortezomib (98.1%) or lenalidomide (100%) and previous lines of therapy were median 3 lines. Significantly better overall response rate (ORR) was seen in the PCd (75.6%) than Pd (41.7%) group (p = 0.001), but no differences in survival outcomes. Subgroup analysis revealed that high-risk myeloma features, poor response to lenalidomide or bortezomib had superior ORRs when cyclophosphamide was added. Also, long-term responders for pomalidomide were associated with excellent response to previous IMiD treatments. Pomalidomide-based therapy was discontinued in five patients due to intolerance or adverse events, but there was no mortality during treatment. In conclusion, we showed that pomalidomide-based treatment is still relevant and can ensure durable response in RRMM setting, especially for patients who responded well to previous lenalidomide. Addition of cyclophosphamide to Pd is associated with better ORR, and can be positively considered in fit patients with high-risk MM, extramedullary disease, and less-than-satisfactory response to previous lenalidomide treatment.

Exploiting cancer's drinking problem: regulation and therapeutic potential of macropinocytosis

Macropinocytosis, an evolutionarily conserved endocytic mechanism that mediates non-specific fluid-phase uptake, is potently upregulated by various oncogenic pathways. It is now well appreciated that high macropinocytic activity is a hallmark of many human tumors, which use this adaptation to scavenge extracellular nutrients for fueling cell growth. In the context of the nutrient-scarce tumor microenvironment, this process provides tumor cells with metabolic flexibility. However, dependence on this scavenging mechanism also illuminates a potential metabolic vulnerability. As such, there is a great deal of interest in understanding the molecular underpinnings of macropinocytosis. In this review, we will discuss the most recent advances in characterizing macropinocytosis: the pathways that regulate it, its contribution to the metabolic fitness of cancer cells, and its therapeutic potential.

Development of a reporter gene method to measure the bioactivity of anti-CD38 × CD3 bispecific antibody

Background

A T cell-redirecting bispecific antibody (bsAb) consisting of a tumor-binding unit and a T cell-binding unit is a large group of antibody-based biologics against death-causing cancer diseases. The anti-CD38 × anti-CD3 bsAb (Y150) is potential for treating multiple myeloma (MM). When developing a cell-based reporter gene bioassay to assess the activities of Y150, it was found that the expression of CD38 on the human T lymphocyte cells (Jurkat) caused the nonspecific activation, which interfered with the specific T cells activation of mediated by the Y150 and CD38(+) tumor cells.

Methods

Here, we first knocked-out the CD38 expression on Jurkat T cell line by CRISPR-Cas9 technology, then developed a stable monoclonal CD38(−) Jurkat T cell line with an NFAT-RE driving luciferase expressing system. Further based on the CD38(−) Jurkat cell, we developed a reporter gene method to assess the bioactivity of the anti-CD38 × anti-CD3 bsAb.

Results

Knocking out CD38 expression abolished the nonspecific self-activation of the Jurkat cells. The selected stable monoclonal CD38(−) Jurkat T cell line assured the robustness of the report genes assay for the anti-CD38 × anti-CD3 bsAb. The relative potencies of the Y150 measured by the developed reporter gene assay were correlated with those by the flow-cytometry-based cell cytotoxicity assay and by the ELISA-based binding assay.

Conclusions

The developed reporter gene assay was mechanism of action-reflective for the bioactivity of anti-CD38 × anti-CD3 antibody, and suitable for the quality control for the bsAb product.

Tissue biodistribution and tumor targeting of near-infrared labelled anti-CD38 antibody-drug conjugate in preclinical multiple myeloma

Daratumumab (DARA) is an FDA-approved high-affinity monoclonal antibody targeting CD38 that has shown promising therapeutic efficacy in double refractory multiple myeloma (MM) patients. Despite the well-established clinical efficacy of DARA, not all heavily pretreated patients respond to single-agent DARA, and the majority of patients who initially respond eventually progress. Antibody-drug conjugates (ADCs) combine the highly targeted tumor antigen recognition of antibodies with the cell killing properties of chemotherapy for effective internalization and processing of the drug. In this study, we evaluated the anti-tumor efficacy of DARA conjugated to the maytansine derivative, mertansine (DM1), linked via a non-cleavable bifunctional linker. The ADC was labelled with the near-infrared (NIR) fluorophore IRDye800 (DARA-DM1-IR) to evaluate its stability, biodistribution and pharmacokinetics in vitro and in vivo. We demonstrated the conjugation of: 1) DM1 enhanced tumor-killing efficacy of the native DARA and 2) IRDye800 allowed for visualization of uptake and tumor targeting ability of the ADC. With the advent of other classes of immunoconjugates for use in MM, we reasoned that such imaging techniques can be utilized to evaluate other promising conjugates in preclinical MM models on a whole-body and cellular level.

Induction Therapy Strategies in the Transplant-Ineligible Population

ABSTRACT

Multiple myeloma (MM), a plasma cell malignancy, accounts for ~10% of hematologic malignancies and predominantly affects the older population. It exhibits a heterogeneous biology and a complex genetic phenotype that affect patient prognosis. The treatment of MM has evolved significantly over the last decade with the use of autologous stem cell transplantation and several novel agents. Consequently, outcomes have improved in this time period, with the most impact in younger patients. Management of MM in elderly frail patients requires a thoughtful approach as majority of these patients carry multiple comorbidities and are precluded from high-dose chemotherapy and autologous stem cell transplantation-accounting for the more modest improvement in outcomes. Assessing transplant eligibility and performance status is a critical first step. Subsequently, the choice of frontline therapy in transplant-ineligible frail patients must balance efficacy with adverse effects to optimize quality of life. Here, we review the current state of induction regimens in this patient population.

Individualized genetic makeup that controls natural killer cell function influences the efficacy of isatuximab immunotherapy in patients with multiple myeloma

BACKGROUND

Phase IIb clinical trial with isatuximab (Isa)-lenalidomide (Len)-dexamethasone (Dex) showed an improved progression-free survival (PFS) in patients with relapsed or refractory multiple myeloma (RRMM), but the efficacy varied by patient. Antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) cells plays a crucial role in arbitrating antitumor activities of therapeutic-antibodies. We tested if patient-specific genetic makeup known to set NK cell functional threshold influence response to Isa-Len-Dex therapy.

METHODS

We characterized 57 patients with RRMM receiving Isa-Len-Dex for polymorphisms of killer-cell immunoglobulin-like receptors (KIR), human leukocyte antigen (HLA) class I, and FCGR3A loci. In vitro ADCC assay, coincubating primary NK cells expressing specific KIR repertoire with multiple myeloma cell lines (MM cells) expressing selected HLA class I ligands, was used to confirm the identified genetic correlatives of clinical response.

RESULTS

Patients with KIR3DL2+ and its cognate-ligand HLA-A3/11+ had superior PFS than patients missing this combination (HR=0.43; p=0.02), while patients carrying KIR2DL1+ and HLA-C2C2+ compared with to patients missing this pair showed short PFS (HR=3.54; p=0.05). Patients with KIR3DL2+ and HLA-A3/11+ plus high-affinity FCGR3A-158V allele showed the most prolonged PFS (HR=0.35; p=0.007). Consistent with these clinical data, mechanistic experiments demonstrated that NK cells expressing KIR3DL2 trigger greater ADCC when MM cells express HLA-A3/11. Inversely, NK cells expressing KIR2DL1 do not kill if MM cells express the HLA-C2C2 ligand. NK cells expressing high-affinity FCGR3A-158VV-induced greater ADCC compared with those with low-affinity FCGR3A-158FF.

CONCLUSIONS

Our results suggest that KIR3DL2+ and HLA-A3/11+ with FCGR3A-158V markers lead to enhanced Isa-dependent NK-mediated cytolysis against MM cells and results in improved PFS in patients with RRMM treated by Isa-Len-Dex. Moreover, the presence of KIR2DL1+ and HLA-C2C2+ identifies patients who may have a lower response to Isa-Len-Dex therapy linked to a reduced NK-mediated ADCC. These biomarkers could potentially identify, via precision medicine, patients more likely to respond to Isa-Len-Dex immunotherapy.

TRIAL REGISTRATION NUMBER

NCT01749969.

Emerging New Approaches in Desensitization: Targeted Therapies for HLA Sensitization

There is an urgent need for therapeutic interventions for desensitization and antibody-mediated rejection (AMR) in sensitized patients with preformed or de novo donor-specific HLA antibodies (DSA). The risk of AMR and allograft loss in sensitized patients is increased due to preformed DSA detected at time of transplant or the reactivation of HLA memory after transplantation, causing acute and chronic AMR. Alternatively, de novo DSA that develops post-transplant due to inadequate immunosuppression and again may lead to acute and chronic AMR or even allograft loss. Circulating antibody, the final product of the humoral immune response, has been the primary target of desensitization and AMR treatment. However, in many cases these protocols fail to achieve efficient removal of all DSA and long-term outcomes of patients with persistent DSA are far worse when compared to non-sensitized patients. We believe that targeting multiple components of humoral immunity will lead to improved outcomes for such patients. In this review, we will briefly discuss conventional desensitization methods targeting antibody or B cell removal and then present a mechanistically designed desensitization regimen targeting plasma cells and the humoral response.

Resveratrol induces AMPK and mTOR signaling inhibition-mediated autophagy and apoptosis in multiple myeloma cells

Resveratrol, a natural compound extracted from the skins of grapes, berries, or other fruits, has been shown to have anti-tumor effects against multiple myeloma (MM) via promoting apoptosis and inhibiting cell viability. In addition to apoptosis, autophagy also plays a significant role in anti-tumor effects. However, whether autophagy is involved in anti-MM activity of resveratrol remains unclear. In this study, human MM cell lines U266, RPMI-8226, and NCI-H929 were treated with resveratrol. Cell Counting Kit-8 assay and colony formation assay were used to measure cell viability. Western blot analysis was used to detect apoptosis- and autophagy-associated proteins. 3-Methyladenine (3-MA) was applied to inhibit autophagy. Results showed that resveratrol inhibited cell viability and colony formation via promoting apoptosis and autophagy in MM cell lines U266, RPMI-8226, and NCI-H929. Resveratrol promoted apoptosis-related proteins, Caspase-3 activating poly-ADP-ribose polymerase and Caspase-3 cleavage, and decreased the protein level of Survivin in a dose-dependent manner. Additionally, resveratrol upregulated the levels of LC3 and Beclin1 in a dose-dependent way, indicating that autophagy might be implicated in anti-MM effect of resveratrol. Furthermore, 3-MA relieved the cytotoxicity of resveratrol by blocking the autophagic flux. Resveratrol increased the phosphorylation of adenosine monophosphate (AMP)-activated protein kinase and decreased the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream substrates p70S6K and 4EBP1 in a dose-dependent manner, leading to autophagy. Therefore, our results suggest that resveratrol exerts anti-MM effects through apoptosis and autophagy, which can be used as a new therapeutic strategy for MM in clinic.

B-Cell Regeneration Profile and Minimal Residual Disease Status in Bone Marrow of Treated Multiple Myeloma Patients

B-cell regeneration during therapy has been considered as a strong prognostic factor in multiple myeloma (MM). However, the effects of therapy and hemodilution in bone marrow (BM) B-cell recovery have not been systematically evaluated during follow-up. MM (n = 177) and adult (≥50y) healthy donor (HD; n = 14) BM samples were studied by next-generation flow (NGF) to simultaneously assess measurable residual disease (MRD) and residual normal B-cell populations. BM hemodilution was detected in 41 out of 177 (23%) patient samples, leading to lower total B-cell, B-cell precursor (BCP) and normal plasma cell (nPC) counts. Among MM BM, decreased percentages (vs. HD) of BCP, transitional/naïve B-cell (TBC/NBC) and nPC populations were observed at diagnosis. BM BCP increased after induction therapy, whereas TBC/NBC counts remained abnormally low. At day+100 postautologous stem cell transplantation, a greater increase in BCP with recovered TBC/NBC cell numbers but persistently low memory B-cell and nPC counts were found. At the end of therapy, complete response (CR) BM samples showed higher CD19^- nPC counts vs. non-CR specimens. MRD positivity was associated with higher BCP and nPC percentages. Hemodilution showed a negative impact on BM B-cell distribution. Different BM B-cell regeneration profiles are present in MM at diagnosis and after therapy with no significant association with patient outcome.

Adaptive Natural Killer Cells Facilitate Effector Functions of Daratumumab in Multiple Myeloma

PURPOSE

To investigate the different roles of heterogeneous natural killer (NK)-cell subpopulations in multiple myeloma and to identify NK-cell subsets that support the robust anti-myeloma activity of daratumumab via antibody-dependent cellular cytotoxicity (ADCC).

EXPERIMENTAL DESIGN

We performed single-cell RNA sequencing of NK cells from patients with newly diagnosed multiple myeloma (NDMM) and delineated adaptive NK cells in their bone marrow (BM). We further characterized the distinct immunophenotypic features and functions of adaptive NK cells by multicolor flow cytometry in 157 patients with NDMM.

RESULTS

Adaptive NK cells exhibit a significantly lower level of CD38 expression compared with conventional NK cells, suggesting that they may evade daratumumab-induced fratricide. Moreover, adaptive NK cells exert robust daratumumab-mediated effector functions ex vivo, including cytokine production and degranulation, compared with conventional NK cells. The composition of adaptive NK cells in BM determines the daratumumab-mediated ex vivo functional activity of BM NK cells in patients with NDMM. Unlike conventional NK cells, sorted adaptive NK cells from the BM of patients with NDMM exert substantial cytotoxic activity against myeloma cells in the presence of daratumumab.

CONCLUSIONS

Our findings indicate that adaptive NK cells are an important mediator of ADCC in multiple myeloma and support direct future efforts to better predict and improve the treatment outcome of daratumumab by selectively employing adaptive NK cells.

PCSK9: A Key Target for the Treatment of Cardiovascular Disease (CVD)

Proprotein convertase subtilisin/kexin type 9 (PCSK9), as a vital modulator of low-density lipoprotein cholesterol (LDL-C) , is raised in hepatocytes and released into plasma where it binds to LDL receptors (LDLR), leading to their cleavage. PCSK9 adheres to the epidermal growth factor-like repeat A (EGF-A) domain of the LDLR which is confirmed by crystallography. LDLR expression is adjusted at the transcriptional level through sterol regulatory element binding protein 2 (SREBP-2) and at the post translational stages, specifically through PCSK9, and the inducible degrader of the LDLR PCSK9 inhibition is an appealing new method for reducing the concentration of LDL-C. In this review the role of PCSK9 in lipid homeostasis was elucidated, the effect of PCSK9 on atherosclerosis was highlighted, and contemporary therapeutic techniques that focused on PCSK9 were summarized. Several restoration methods to inhibit PCSK9 have been proposed which concentrate on both extracellular and intracellular PCSK9, and they include blockage of PCSK9 production by using gene silencing agents and blockage of it's binding to LDLR through antibodies and inhibition of PCSK9 autocatalytic processes by tiny molecule inhibitors.

ImmunoPET in Multiple Myeloma-What? So What? Now What?

Despite constant progress over the past three decades, multiple myeloma (MM) is still an incurable disease, and the identification of new biomarkers to better select patients and adapt therapy is more relevant than ever. Recently, the introduction of therapeutic monoclonal antibodies (mAbs) (including direct-targeting mAbs and immune checkpoint inhibitors) appears to have changed the paradigm of MM management, emphasizing the opportunity to cure MM patients through an immunotherapeutic approach. In this context, immuno-positron emission tomography (immunoPET), combining the high sensitivity and resolution of a PET camera with the specificity of a radiolabelled mAb, holds the capability to cement this new treatment paradigm for MM patients. It has the potential to non-invasively monitor the distribution of therapeutic antibodies or directly monitor biomarkers on MM cells, and to allow direct observation of potential changes over time and in response to various therapeutic interventions. Tumor response could, in the future, be anticipated more effectively to provide individualized treatment plans tailored to patients according to their unique imaging signatures. This work explores the important role played by immunotherapeutics in the management of MM, and focuses on some of the challenges for this drug class and the significant interest of companion imaging agents such as immunoPET.

Multiple Myeloma: Available Therapies and Causes of Drug Resistance

Multiple myeloma (MM) is the second most common blood cancer. Treatments for MM include corticosteroids, alkylating agents, anthracyclines, proteasome inhibitors, immunomodulatory drugs, histone deacetylase inhibitors and monoclonal antibodies. Survival outcomes have improved substantially due to the introduction of many of these drugs allied with their rational use. Nonetheless, MM patients successively relapse after one or more treatment regimens or become refractory, mostly due to drug resistance. This review focuses on the main drugs used in MM treatment and on causes of drug resistance, including cytogenetic, genetic and epigenetic alterations, abnormal drug transport and metabolism, dysregulation of apoptosis, autophagy activation and other intracellular signaling pathways, the presence of cancer stem cells, and the tumor microenvironment. Furthermore, we highlight the areas that need to be further clarified in an attempt to identify novel therapeutic targets to counteract drug resistance in MM patients.

Alterations in the Transcriptional Programs of Myeloma Cells and the Microenvironment during Extramedullary Progression Affect Proliferation and Immune Evasion

PURPOSE

In multiple myeloma, extramedullary progression is associated with treatment resistance and a high mortality rate. To understand the molecular mechanisms controlling the devastating progression of myeloma, we applied single-cell RNA-sequencing (RNA-seq) to myeloma in the bone marrow and myelomatous pleural effusions or ascites.

EXPERIMENTAL DESIGN

Bone marrow or extramedullary myeloma samples were collected from 15 patients and subjected to single-cell RNA-seq. The single-cell transcriptome data of malignant plasma cells and the surrounding immune microenvironment were analyzed.

RESULTS

Comparisons of single-cell transcriptomes revealed the systematic activation of proliferation, antigen presentation, proteasomes, glycolysis, and oxidative phosphorylation pathways in extramedullary myeloma cells. The myeloma cells expressed multiple combinations of growth factors and receptors, suggesting autonomous and pleiotropic growth potential at the single-cell level. Comparisons of the tumor microenvironment revealed the presence of cytotoxic T lymphocytes and natural killer (NK) cells in both the bone marrow and extramedullary ascites, demonstrating a gene-expression phenotype indicative of functional compromise. In parallel, isolated myeloma cells persistently expressed class I MHC molecules and upregulated inhibitory molecules for cytotoxic T and NK cells.

CONCLUSIONS

These data suggest that myeloma cells are equipped with specialized immune evasion mechanisms in cytotoxic microenvironments. Taken together, single-cell transcriptome analysis revealed transcriptional programs associated with aggressive myeloma progression that support autonomous cell proliferation and immune evasion.

Dynamic CD138 surface expression regulates switch between myeloma growth and dissemination

The canonical plasma cell marker CD138 (syndecan-1) is highly expressed on the myeloma cell surface, but its functional role in vivo is unclear, as well as the ontogeny of CD138-high and CD138-negative (neg) myeloma cells. In this study we used an in vivo murine Vk*MYC myeloma model where CD138 is heterogeneously expressed depending on tumor size. We find that in comparison to CD138-neg myeloma cells, the CD138-high subset of myeloma cells is highly proliferative, less apoptotic, and enhanced IL-6R signaling, which is known to promote survival. In addition CD138-high myeloma engrafts better than its CD138-neg counterpart. In contrast, CD138-neg cells are more motile both in vitro and in vivo, and more readily disseminate and spread to other bones in vivo than CD138-high subset. Neutralizing CD138 rapidly triggers migration of myeloma cells in vivo and leads to intravasation, which results in increased dissemination to other bones. Both murine and human myeloma cells can rapidly recycle CD138 surface expression through endocytic trafficking, in response to serum levels. Blocking CD138 enhances myeloma sensitivity to bortezomib chemotherapy and significantly reduces tumor size compared to bortezomib treatment alone. Thus, our data show that CD138 surface expression dynamically regulates a switch between growth vs. dissemination for myeloma, in response to nutrient conditions.

The role of CXCR4 in multiple myeloma: Cells' journey from bone marrow to beyond

CXCR4 is a pleiotropic chemokine receptor which acts through its ligand CXCL12 to regulate diverse physiological processes. CXCR4/CXCL12 axis plays a pivotal role in proliferation, invasion, dissemination and drug resistance in multiple myeloma (MM). Apart from its role in homing, CXCR4 also affects MM cell mobilization and egression out of the bone marrow (BM) which is correlated with distant organ metastasis. Aberrant CXCR4 expression pattern is associated with osteoclastogenesis and tumor growth in MM through its cross talk with various important cell signalling pathways. A deeper insight into understanding of CXCR4 mediated signalling pathways and its role in MM is essential to identify potential therapeutic interventions. The current therapeutic focus is on disrupting the interaction of MM cells with its protective tumor microenvironment where CXCR4 axis plays an essential role. There are still multiple challenges that need to be overcome to target CXCR4 axis more efficiently and to identify novel combination therapies with existing strategies. This review highlights the role of CXCR4 along with its significant interacting partners as a mediator of MM pathogenesis and summarizes the targeted therapies carried out so far.

Elotuzumab: A Review in Relapsed and/or Refractory Multiple Myeloma

Intravenous elotuzumab (Empliciti™), a monoclonal antibody targeting the signalling lymphocytic activation molecule F7 (SLAMF7) glycoprotein, is approved for use in combination with lenalidomide and dexamethasone for the treatment of multiple myeloma in previously-treated adult patients. In the pivotal, multinational, phase III ELOQUENT-2 trial in adults with relapsed and/or refractory multiple myeloma, elotuzumab in combination with lenalidomide and dexamethasone significantly prolonged median progression-free survival (PFS) and increased overall response rate (ORR; co-primary endpoints) compared with lenalidomide and dexamethasone alone. The clinical benefit of elotuzumab was maintained over the longer term (≤ 4 years' minimum follow-up); final overall survival data are awaited. Health-related quality of life was not negatively impacted by the addition of elotuzumab. Elotuzumab combination therapy had a generally manageable tolerability profile and the most common adverse events (AEs) of grade ≥ 3 severity were haematological (e.g. lymphocytopenia, anaemia, thrombocytopenia, neutropenia). Elotuzumab plus lenalidomide and dexamethasone extends the treatment options available for the management of relapsed and/or refractory multiple myeloma.

What is the Best Radionuclide for Immuno-PET of Multiple Myeloma? A Comparison Study Between 89Zr- and 64Cu-Labeled Anti-CD138 in a Preclinical Syngeneic Model

Although positron emission tomography (PET) imaging with 18-Fluorodeoxyglucose (¹⁸F-FDG) is a promising technique in multiple myeloma (MM), the development of other radiopharmaceuticals seems relevant. CD138 is currently used as a standard marker for the identification of myeloma cells and could be used in phenotype tumor imaging. In this study, we used an anti-CD138 murine antibody (9E7.4) radiolabeled with copper-64 (⁶⁴Cu) or zirconium-89 (⁸⁹Zr) and compared them in a syngeneic mouse model to select the optimal tracers for MM PET imaging. Then, 9E7.4 was conjugated to TE2A-benzyl isothiocyanate (TE2A) and desferrioxamine (DFO) chelators for ⁶⁴Cu and ⁸⁹Zr labeling, respectively. ⁶⁴Cu-TE2A-9E7.4 and ⁸⁹Zr-DFO-9E7.4 antibodies were evaluated by PET imaging and biodistribution studies in C57BL/KaLwRij mice bearing either 5T33-MM subcutaneous tumors or bone lesions and were compared to ¹⁸F-FDG-PET imaging. In biodistribution and PET studies, ⁶⁴Cu-TE2A-9E7.4 and ⁸⁹Zr-DFO-9E7.4 displayed comparable good tumor uptake of subcutaneous tumors. On the bone lesions, PET imaging with ⁶⁴Cu-TE2A-9E7.4 and ⁸⁹Zr-DFO-9E7.4 showed higher uptake than with ¹⁸F-FDG-PET. Comparison of both 9E7.4 conjugates revealed higher nonspecific bone uptakes of ⁸⁹Zr-DFO-9E7.4 than ⁶⁴Cu-TE2A-9E7.4. Because of free ⁸⁹Zr’s tropism for bone when using ⁸⁹Zr-anti-CD138, ⁶⁴Cu-anti-CD138 antibody had the most optimal tumor-to-nontarget tissue ratios for translation into humans as a specific new imaging radiopharmaceutical agent in MM.

Systemic Delivery of Monoclonal Antibodies to the Central Nervous System for Brain Tumor Therapy

As an essential component of immunotherapy, monoclonal antibodies (mAbs) have emerged as a class of powerful therapeutics for treatment of a broad range of diseases. For central nervous system (CNS) diseases, however, the efficacy remains limited due to their inability to enter the CNS. A platform technology is reported here that enables effective delivery of mAbs to the CNS for brain tumor therapy. This is achieved by encapsulating the mAbs within nanocapsules that contain choline and acetylcholine analogues; such analogues facilitate the penetration of the nanocapsules through the brain-blood barrier and the delivery of mAbs to tumor sites. This platform technology uncages the therapeutic power of mAbs for various CNS diseases that remain poorly treated.

Development of Novel Epoxyketone-Based Proteasome Inhibitors as a Strategy To Overcome Cancer Resistance to Carfilzomib and Bortezomib

Over the past 15 years, proteasome inhibitors (PIs), namely bortezomib, carfilzomib (Cfz) and ixazomib, have significantly improved the overall survival and quality-of-life for multiple myeloma (MM) patients. However, a significant portion of MM patients do not respond to PI therapies. Drug resistance is present either de novo or acquired after prolonged therapy through mechanisms that remain poorly defined. The lack of a clear understanding of clinical PI resistance has hampered the development of next-generation PI drugs to treat MM patients who no longer respond to currently available therapies. Here, we designed and synthesized novel epoxyketone-based PIs by structural modifications at the P1' site. We show that a Cfz analog, 9, harboring a hydroxyl substituent at its P1' position was highly cytotoxic against cancer cell lines displaying de novo or acquired resistance to Cfz. These results suggest that peptide epoxyketones incorporating P1'-targeting moieties may have the potential to bypass resistance mechanisms associated with Cfz and to provide additional clinical options for patients resistant to Cfz.

Phase I trial of isatuximab monotherapy in the treatment of refractory multiple myeloma

This phase I dose-escalation/expansion study evaluated isatuximab (anti-CD38 monoclonal antibody) monotherapy in patients with relapsed/refractory multiple myeloma (RRMM). Patients progressing on or after standard therapy received intravenous isatuximab (weekly [QW] or every 2 weeks [Q2W]). The primary objective was to determine the maximum tolerated dose (MTD) of isatuximab. Overall, 84 patients received ≥ 1 dose of isatuximab. The MTD was not reached; no cumulative adverse reactions were noted. The most frequent adverse events were infusion reactions (IRs), occurring in 37/73 patients (51%) following introduction of mandatory prophylaxis. IRs were mostly grade 1/2, occurred predominantly during Cycle 1, and led to treatment discontinuation in two patients. CD38 receptor occupancy reached a plateau of 80% with isatuximab 20 mg/kg (highest dose tested) and was associated with clinical response. In patients receiving isatuximab ≥ 10 mg/kg, overall response rate (ORR) was 23.8% (15/63), including one complete response. In high-risk patients treated with isatuximab 10 mg/kg (QW or Q2W), ORR was 16.7% (3/18). Median (range) duration of response at doses ≥ 10 mg/kg was 25 (8–30) weeks among high-risk patients versus 36 (6–85) weeks for other patients. In conclusion, isatuximab demonstrated a manageable safety profile and clinical activity in patients with RRMM.

Indatuximab Ravtansine (BT062) Monotherapy in Patients With Relapsed and/or Refractory Multiple Myeloma

BACKGROUND

Indatuximab ravtansine (BT062) is an antibody-drug conjugate that binds to CD138, which is overexpressed on multiple myeloma (MM) cells.

PATIENTS AND METHODS

We report from 2 clinical studies of patients with relapsed and/or refractory MM previously treated with an immunomodulatory drug and a proteasome inhibitor. Single- and multi-dosing schedules were investigated to define dose-limiting toxicities, maximum tolerated dose (MTD), recommended phase II dose, and to describe safety, efficacy, and pharmacokinetics.

RESULTS

In the first-in-human study, indatuximab ravtansine was administered to 32 patients on day 1 of each 21-day cycle. The MTD was 160 mg/m². In the phase I/IIa study, indatuximab ravtansine was administered to 35 patients on days 1, 8, and 15 of each 28-day cycle, and the MTD/recommended phase II dose was 140 mg/m². Most (88%) adverse events were grade 1 or 2, the most common being diarrhea and fatigue. There was rapid clearance of indatuximab ravtansine and no relevant accumulation. Over 75% of heavily pretreated patients achieved stable disease or better. With the multi-dose schedule, minor and partial responses occurred in 14.7% of patients, the median time to progression was 3 months, and the median overall survival was 26.7 months.

CONCLUSION

Our data support further investigation of indatuximab ravtansine as part of a combination regimen for relapsed and/or refractory MM.

Navigating the treatment landscape in multiple myeloma: which combinations to use and when?

Multiple myeloma is one of the most common hematological malignancies, affecting mainly elderly patients. The treatment landscape for the management of this disease has evolved significantly over the past 15 years, and a vast array of therapeutics is now available, including immunomodulatory drugs, proteasome inhibitors, histone deacetylase inhibitors, and monoclonal antibodies. As a result, deciding which drugs to use and when, and whether these should be used in a particular order or combination, can be challenging. Although combination regimens are often associated with deeper responses and better long-term outcomes than monotherapy, and are becoming the standard of care, they may result in significant incremental toxicity; hence, a sequential approach may be more appropriate for some patients. In particular, treatment choices can vary depending on whether the patient has newly diagnosed multiple myeloma, is eligible for transplant, has relapsed and/or refractory multiple myeloma, or is considered to have high-risk disease. In this review, we discuss factors to be taken into account when making treatment decisions in each of these settings. We also briefly discuss possible therapeutic strategies involving agents that may become available in the future.

Monoclonal Antibodies for the Treatment of Multiple Myeloma: An Update

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

Pathological roles of the homeostatic chemokine CXCL12

CXCL12 is a CXC chemokine that traditionally has been classified as a homeostatic chemokine. It contributes to physiological processes such as embryogenesis, hematopoiesis and angiogenesis. In contrast to these homeostatic functions, increased expression of CXCL12 in general, or of a specific CXCL12 splicing variant has been demonstrated in various pathologies. In addition to this increased or differential transcription of CXCL12, also upregulation of its receptors CXC chemokine receptor 4 (CXCR4) and atypical chemokine receptor 3 (ACKR3) contributes to the onset or progression of diseases. Moreover, posttranslational modification of CXCL12 during disease progression, through interaction with locally produced molecules or enzymes, also affects CXCL12 activity, adding further complexity. As CXCL12, CXCR4 and ACKR3 are broadly expressed, the number of pathologies wherein CXCL12 is involved is growing. In this review, the role of the CXCL12/CXCR4/ACKR3 axis will be discussed for the most prevalent pathologies. Administration of CXCL12-neutralizing antibodies or small-molecule antagonists of CXCR4 or ACKR3 delays disease onset or prevents disease progression in cancer, viral infections, inflammatory bowel diseases, rheumatoid arthritis and osteoarthritis, asthma and acute lung injury, amyotrophic lateral sclerosis and WHIM syndrome. On the other hand, CXCL12 has protective properties in Alzheimer's disease and multiple sclerosis, has a beneficial role in wound healing and has crucial homeostatic properties in general.

Daratumumab: A Review in Relapsed and/or Refractory Multiple Myeloma

Intravenous daratumumab (DARZALEX^®) is a first-in-class human IgG1κ monoclonal antibody against CD38 available for use in patients with relapsed and/or refractory multiple myeloma. In phase I/II and II trials and a pooled analysis of these studies, daratumumab monotherapy induced an overall response (partial response or better) in approximately one-third of patients; responses were rapid, deep and durable. An overall survival (OS) benefit was seen with daratumumab monotherapy, including in patients with a minimal response or stable disease. In phase III trials, daratumumab in combination with either bortezomib plus dexamethasone or lenalidomide plus dexamethasone significantly prolonged progression-free survival and induced deep and durable responses compared with bortezomib plus dexamethasone or lenalidomide plus dexamethasone. An OS benefit with daratumumab triple combination therapy is yet to be demonstrated (as the OS data were not mature at the time of the last analysis). Daratumumab was generally well tolerated when used as monotherapy and had a generally manageable tolerability profile when used in combination therapy. Infusion-related reactions (IRRs) were the most common adverse events; these were predominantly grade 1 or 2 and mostly occurred during the first infusion. The most common grade 3-4 adverse events associated with daratumumab triple combination therapy were thrombocytopenia, neutropenia and anaemia. Although final OS data are awaited, current evidence indicates that daratumumab is a valuable addition to the treatment options currently available for patients with relapsed or refractory multiple myeloma.

Quantification of number of CD38 sites on bone marrow plasma cells in patients with light chain amyloidosis and smoldering multiple myeloma

BACKGROUND

Recent approaches in multiple myeloma (MM) treatment have targeted CD38. As antigen expression levels on plasma cells (PCs) were demonstrated to affect response to monoclonal antibody (mAb) treatment, a precise characterization of PC phenotype is warranted.

METHODS

Anti-CD38 mAb (isatuximab) was tested for antibody-dependent cellular cytotoxicity (ADCC) in MM cell lines. Quantification of the number of sites (NOS) of CD38 on bone marrow PCs and other immune cells obtained from light chain (AL) amyloidosis (n = 46) and smoldering multiple myeloma (SMM) patients (n = 19) was performed with two different quantitative flow cytometry (QFCM) applications.

RESULTS

ADCC activity of isatuximab was observed in cell lines with >100 × 10³ CD38-NOS only. The average PC CD38-NOS was 153 ± 53 × 10³ in AL amyloidosis and 138.7 ± 53 × 10³ in SMM patients. Eight (17%) AL amyloidosis and 4 (21%) SMM patients showed a PC CD38-NOS level <100 × 10³ . In four AL amyloidosis and two SMM patients <10% of PCs had a CD38-NOS ≥100 × 10³ . The CD38-NOS identified on bone marrow lymphocytes, monocytes, and granulocytes was two log units below the CD38-NOS on PCs (P < 0.001). No significant differences in CD38-NOS expression levels on any of the analyzed PC subpopulations in AL amyloidosis and SMM patients were identified.

CONCLUSION

Levels of CD38 expression affect the isatuximab-mediated ADCC in vitro. As PCs of patients with AL amyloidosis and SMM do not homogenously express high CD38 our data provide a rationale for assessment of CD38-NOS in patients with PC disorders prior to anti-CD38 treatment. © 2018 International Clinical Cytometry Society.

Potent antitumor effect of combination therapy with sub-optimal doses of Akt inhibitors and pomalidomide plus dexamethasone in multiple myeloma

Afuresertib (AFU), a novel inhibitor of the serine/threonine kinase AKT, has clinical efficacy as a monotherapy against hematological malignancies and is expected to be used in combination with standard therapies for multiple myeloma (MM). To develop a more effective and less toxic combination of immunomodulatory drugs (IMiDs) for therapy, the antitumor effect of sub-optimal doses of AFU, pomalidomide plus dexamethasone (PD), and the AFU-PD combination on MM cells were examined in the present study. Two MM cell lines, XG-7 and U266, with low sensitivity to both PD and AFU monotherapies, were subjected to these combinations and analyzed. Although the cell lines showed a slight reduction in viability with the sub-optimal doses of each monotherapy, the combination of the treatments resulted in a reduction in cell viability and the progression of apoptosis. Co-treatment with sub-optimal doses of PD and AFU enhanced caspase activation and highly suppressed the expression of IKZF1 and IKZF3. In addition, this combination promoted the dephosphorylation and stabilization of 4EBP1, an inhibitor of eIF4E activation, which led to the impairment of eIF4E-mediated translational activity. Furthermore, AFU showed a sufficient inhibitory effect on the phosphorylation of FOXO1, a tumor suppressor, in monotherapy or in combination with PD, which may be attributable to the activation of FOXO1, the subsequent inhibition of tumor growth, and the induction of cell death. In conclusion, the combination therapy with sub-optimal doses of PD and AFU exhibited potent antitumor activity in MM cells and may provide a novel strategy for the treatment of patients who experienced intolerable toxicity or insufficient response during IMiD therapy.

Efficacy and Mechanism of Antitumor Activity of an Antibody Targeting Transferrin Receptor 1 in Mouse Models of Human Multiple Myeloma

The transferrin receptor 1 (TfR1) is an attractive target for Ab-mediated cancer therapy. We previously developed a mouse/human chimeric IgG3 Ab (ch128.1) targeting human TfR1, which exhibits direct in vitro cytotoxicity against certain human malignant B cells through TfR1 degradation and iron deprivation. ch128.1 also demonstrates exceptional antitumor activity against the B cell malignancy multiple myeloma (MM) in xenograft models of SCID-Beige mice bearing either disseminated ARH-77 or KMS-11 cells in an early disease setting. Interestingly, this activity is observed even against KMS-11 cells, which show no sensitivity to the direct cytotoxic activity of ch128.1 in vitro. To understand the contributions of the Fc fragment, we generated a ch128.1 mutant with impaired binding to FcγRs and to the complement component C1q, which retains binding to the neonatal Fc receptor. We now report that this mutant Ab does not show antitumor activity in these two MM models, indicating a crucial role of the Fc fragment in the antitumor activity of ch128.1, which can be attributed to effector functions (Ab-dependent cell-mediated cytotoxicity, Ab-dependent cell-mediated phagocytosis, and/or complement-dependent cytotoxicity). Interestingly, in the KMS-11 model, complement depletion does not affect protection, whereas macrophage depletion does. Consistent with this observation, we found that ch128.1 induces Ab-dependent cell-mediated cytotoxicity and Ab-dependent cell-mediated phagocytosis against KMS-11 cells in the presence of murine bone marrow-derived macrophages. Finally, we found that ch128.1 therapy effectively increases survival in a late MM disease setting. Our results suggest that macrophages play a major role in ch128.1-mediated antitumor protection in our models and that ch128.1 can be effective against human B cell malignancies such as MM.

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.

Current and New Therapeutic Strategies for Relapsed and Refractory Multiple Myeloma: An Update

Although survival of multiple myeloma patients has at least doubled during recent years, most patients eventually relapse, and treatment at this stage may be particularly complex. At the time of relapse, the use of alternative drugs to those given upfront is current practice. However, many new options are currently available for the treatment of relapsed multiple myeloma, including recently approved drugs, such as the second- and third-generation proteasome inhibitors carfilzomib and ixazomib, the immunomodulatory agent pomalidomide, the monoclonal antibodies daratumumab and elotuzumab and the histone deacetylase inhibitor panobinostat, but also new targeted agents are under active investigation (e.g. signal transduction modulators, kinesin spindle protein inhibitors, and inhibitors of NF-kB, MAPK, AKT). We here describe a new paradigm for the treatment of relapsed multiple myeloma. The final goal should be finding a balance among efficacy, toxicity, and cost and, at the end of the road, achieving long-lasting control of the disease and eventually even cure in a subset of patients.

The good and bad faces of the CXCR4 chemokine receptor

Chemokines are chemotactic cytokines that promote cell migration and activation under homeostatic and inflammatory conditions. Chemokines bind to seven transmembrane-spanning receptors that are coupled to heterotrimeric guanine nucleotide-binding (G) proteins, which are the responsible for intracellularly transmitting the activating signals for cell migration. Hematopoiesis, vascular development, lymphoid organ morphogenesis, cardiogenesis and neural differentiation are amongst the processes involving chemokine function. In addition, immune cell trafficking from bone marrow to blood circulation, and from blood and lymph to lymphoid and inflamed tissues, is tightly regulated by chemokines both under physiological conditions and also in autoimmune diseases. Furthermore, chemokine binding to their receptors stimulate trafficking to and positioning of cancer cells into target tissues and organs during tumour dissemination. The CXCL12 chemokine (also known as stromal-cell derived factor-1α, SDF-1α) plays key roles in hematopoiesis and lymphoid tissue architecture, in cardiogenesis, vascular formation and neurogenesis, as well as in the trafficking of solid and hematological cancer cell types. CXCL12 binds to the CXCR4 receptor, a multi-facetted molecule which tightly mirrors CXCL12 functions in homeostasis and disease. This review addresses the important roles of the CXCR4-CXCL12 axis in homeostasis, specially focusing in hematopoiesis, as well as it provides a picture of CXCR4 as mediator of cancer cell spreading, and a view of the available CXCR4 antagonists in different cancer types.

Immunotherapy Strategies Against Multiple Myeloma

Multiple myeloma is a monoclonal B-cell malignancy characterized by an accumulation of malignant plasma cells in the bone marrow, the presence of a monoclonal protein in the serum and/or urine, decreased normal immunoglobulin levels, and lytic bone disease. Patients with multiple myeloma benefit from combination therapy including novel therapeutic agents followed by autologous stem cell transplantation prolonged maintenance therapy. However, multiple myeloma remains incurable; most patients with multiple myeloma will eventually become resistant to chemotherapy, and progression or relapse of the disease is inevitable. Immunotherapy represents a novel therapeutic approach with few adverse effects and good targeting capability that might be a powerful pool to allow long-term control of minimal residual disease. This article reviews the literature evaluating 4 major immunotherapeutic approaches for multiple myeloma including cellular immunotherapy, humoral immunotherapy, radio immunotherapy, and immunomodulation.

CD86 regulates myeloma cell survival

Although prognosis for patients with multiple myeloma has improved over the past decade, research toward discovery of new therapeutic avenues is important and could lead to a cure for this plasma cell malignancy. Here we show that blocking the CD28-CD86 pathway via silencing of either CD28 or CD86 leads to myeloma cell death. Inhibiting this pathway leads to downregulation of integrins and IRF4, a known myeloma survival factor. Our data also indicate that CD86, the canonical ligand in this pathway, has prosurvival activity that is dependent on its cytosolic domain. These findings indicate that targeting of this pathway is a promising therapeutic avenue for myeloma, because it leads to modulation of different processes important in cell viability.

A novel Fc-engineered human ICAM-1/CD54 antibody with potent anti-myeloma activity developed by cellular panning of phage display libraries

To identify antibodies suitable for multiple myeloma (MM) immunotherapy, a cellular screening approach was developed using plasma cell lines JK-6L and INA-6 and human synthetic single-chain fragment variable (scFv) phage libraries. Isolated phage antibodies were screened for myeloma cell surface reactivity. Due to its binding characteristics, phage PIII-15 was selected to generate the scFv-Fc fusion protein TP15-Fc with an Fc domain optimized for FcγRIIIa binding. Various MM cell lines and patient-derived CD138-positive malignant plasma cells, but not granulocytes, B or T lymphocytes from healthy donors were recognized by TP15-Fc. Human intercellular adhesion molecule-1 (ICAM-1/CD54) was identified as target antigen by using transfected Chinese hamster ovary (CHO) cells. Of note, no cross-reactivity of TP15-Fc with mouse ICAM-1 transfected cells was detected. TP15-Fc was capable to induce antibody-dependent cell-mediated cytotoxicity (ADCC) against different human plasma cell lines and patients' myeloma cells with peripheral blood mononuclear cells (PBMC) and purified NK cells. Importantly, TP15-Fc showed potent in vivo efficacy and completely prevented growth of human INA-6.Tu1 plasma cells in a xenograft SCID/beige mouse model. Thus, the novel ADCC-optimized TP15-Fc exerts potent anti-myeloma activity and has promising characteristics to be further evaluated for MM immunotherapy.

Effect of pomalidomide on relapsed/refractory multiple myeloma: a systematic review and meta-analysis

In this work, we aim to further analyze the effect of pomalidomide for relapsed and/or refractory multiple myeloma (RRMM). A systematic literature search of PubMed, MEDLINE and EMBASE was conducted on September 20, 2016. Pooled effect size (ES) with corresponding 95% confidence intervals (CIs) were calculated using random-effects model. STATA software (version 12.0; Stata Corporation; College Station, TX, USA) was employed to do all statistical analyses. A total of 8 studies were included for analysis. The combined results demonstrated that the pooled proportion of overall response rate (ORR) was 0.35 (95% CI 0.27 to 0.43, P=0.000), and the pooled proportion of complete response rate (CRR) was 0.02 (95% CI 0.01 to 0.03, P=0.541). Pomalidomide was generally well tolerated by patients reported in the studies. Further studies would be required to conduct more prospective randomized controlled trials (RCTs) with larger samples to assess the proper place of pomalidomide as single agent or combined with other agents for RRMM.

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.