Single-Cell Discovery and Multiomic Characterization of Therapeutic Targets in Multiple Myeloma

Multiple myeloma (MM) is a highly refractory hematologic cancer. Targeted immunotherapy has shown promise in MM but remains hindered by the challenge of identifying specific yet broadly representative tumor markers. We analyzed 53 bone marrow (BM) aspirates from 41 MM patients using an unbiased, high-throughput pipeline for therapeutic target discovery via single-cell transcriptomic profiling, yielding 38 MM marker genes encoding cell-surface proteins and 15 encoding intracellular proteins. Of these, 20 candidate genes were highlighted that are not yet under clinical study, 11 of which were previously uncharacterized as therapeutic targets. The findings were cross-validated using bulk RNA sequencing, flow cytometry, and proteomic mass spectrometry of MM cell lines and patient BM, demonstrating high overall concordance across data types. Independent discovery using bulk RNA sequencing reiterated top candidates, further affirming the ability of single-cell transcriptomics to accurately capture marker expression despite limitations in sample size or sequencing depth. Target dynamics and heterogeneity were further examined using both transcriptomic and immuno-imaging methods. In summary, this study presents a robust and broadly applicable strategy for identifying tumor markers to better inform the development of targeted cancer therapy.

SIGNIFICANCE

Single-cell transcriptomic profiling and multiomic cross-validation to uncover therapeutic targets identifies 38 myeloma marker genes, including 11 transcribing surface proteins with previously uncharacterized potential for targeted antitumor therapy.

Blocking the PCNA/NKp44 Checkpoint to Stimulate NK Cell Responses to Multiple Myeloma

Multiple Myeloma (MM) is a devastating malignancy that evades immune destruction using multiple mechanisms. The NKp44 receptor interacts with PCNA (Proliferating Cell Nuclear Antigen) and may inhibit NK cells' functions. Here we studied in vitro the expression and function of PCNA on MM cells. First, we show that PCNA is present on the cell membrane of five out of six MM cell lines, using novel anti-PCNA mAb developed to recognize membrane-associated PCNA. Next, we stained primary bone marrow (BM) mononuclear cells from MM patients and showed significant staining of membrane-associated PCNA in the fraction of CD38+CD138+ BM cells that contain the MM cells. Importantly, blocking of the membrane PCNA on MM cells enhanced the activity of NK cells, including IFN-γ-secretion and degranulation. Our results highlight the possible blocking of the NKp44-PCNA immune checkpoint by the mAb 14-25-9 antibody to enhance NK cell responses against MM, providing a novel treatment option.

IBI379, a novel B cell maturation antigen/CD3 bispecific T-cell engager, displays high antitumor efficacy in preclinical models of multiple myeloma

Multiple myeloma (MM) is a hematological malignancy that results from the malignant proliferation of plasma cells in the bone marrow. B cell maturation antigen (BCMA) is highly selectively expressed in malignant plasma cells and is a novel therapeutic target for MM. Here, we developed a bispecific T cell engager, IBI379, that targets BCMA and CD3, and investigated its antitumor efficacy against MM. IBI379 showed strong binding affinity with both BCMA and CD3, which triggered T cell activation, proliferation, and cytokine release. An in vitro study demonstrated that IBI379 induced the lysis of MM cells expressing differing levels of BCMA on the cell surface. Administration of IBI379 in H929 or Daudi-BCMA cell xenograft mouse models significantly inhibited tumor growth without inducing body weight loss. The mechanism of action study revealed the accumulation of CD4⁺CD8⁺ T cells and granzyme B-positive T cells in tumors that were treated with IBI379. Moreover, administration of low dose of IBI379 in cynomolgus monkeys was well-tolerated and induced the depletion of BCMA⁺ B cells and a mild transient increase of cytokines. Collectively, these results demonstrate that IBI379 is a highly potent therapeutic strategy for depleting BCMA-positive B cells and is a promising approach for the treatment of MM.

Anti-GPRC5D/CD3 Bispecific T-Cell-Redirecting Antibody for the Treatment of Multiple Myeloma

Although treatment advances over recent decades have significantly improved survival of patients with multiple myeloma, there is still an unmet medical need for more effective treatments. In this study, we identified G-protein-coupled receptor family C group 5 member D (GPRC5D) expression on the surface of malignant cells involved in multiple myeloma, but except for plasma cells and B cells, not at appreciable levels on normal hematopoietic cells and bone marrow progenitors, including hematopoietic stem cells. In addition, we constructed IgG-based anti-GPRC5D/CD3 bispecific T-cell-redirecting antibodies (GPRC5D TRAB), which suppressed the tumor growth of GPRC5D-positive myeloma cells through the activation of T cells in vitro and in vivo in xenograft models. Collectively, these findings suggest that GPRC5D is an antigen specific to multiple myeloma and a potential target of TRAB therapy.

New Drugs in Multiple Myeloma

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

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.

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

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

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

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

Epigenetic and genetic dissections of UV-induced global gene dysregulation in skin cells through multi-omics analyses

To elucidate the complex molecular mechanisms underlying the adverse effects UV radiation (UVR) on skin homeostasis, we performed multi-omics studies to characterize UV-induced genetic and epigenetic changes. Human keratinocytes from a single donor treated with or without UVR were analyzed by RNA-seq, exome-seq, and H3K27ac ChIP-seq at 4 h and 72 h following UVR. Compared to the relatively moderate mutagenic effects of UVR, acute UV exposure induced substantial epigenomic and transcriptomic alterations, illuminating a previously underappreciated role of epigenomic and transcriptomic instability in skin pathogenesis. Integration of the multi-omics data revealed that UVR-induced transcriptional dysregulation of a subset of genes was attributable to either genetic mutations or global redistribution of H3K27ac. H3K27ac redistribution further led to the formation of distinctive super enhancers in UV-irradiated cells. Our analysis also identified several new UV target genes, including CYP24A1, GJA5, SLAMF7 and ETV1, which were frequently dysregulated in human squamous cell carcinomas, highlighting their potential as new molecular targets for prevention or treatment of UVR-induced skin cancers. Taken together, our concurrent multi-omics analyses provide new mechanistic insights into the complex molecular networks underlying UV photobiological effects, which have important implications in understanding its impact on skin homeostasis and pathogenesis.

A novel BCMA/CD3 bispecific T-cell engager for the treatment of multiple myeloma induces selective lysis in vitro and in vivo

B-cell maturation antigen (BCMA) is a highly plasma cell-selective protein that is expressed on malignant plasma cells of multiple myeloma (MM) patients and therefore is an ideal target for T-cell redirecting therapies. We developed a bispecific T-cell engager (BiTE) targeting BCMA and CD3ɛ (BI 836909) and studied its therapeutic impacts on MM. BI 836909 induced selective lysis of BCMA-positive MM cells, activation of T cells, release of cytokines and T-cell proliferation; whereas BCMA-negative cells were not affected. Activity of BI 836909 was not influenced by the presence of bone marrow stromal cells, soluble BCMA or a proliferation-inducing ligand (APRIL). In ex vivo assays, BI 836909 induced potent autologous MM cell lysis in both, newly diagnosed and relapsed/refractory patient samples. In mouse xenograft studies, BI 836909 induced tumor cell depletion in a subcutaneous NCI-H929 xenograft model and prolonged survival in an orthotopic L-363 xenograft model. In a cynomolgus monkey study, administration of BI 836909 led to depletion of BCMA-positive plasma cells in the bone marrow. Taken together, these results show that BI 836909 is a highly potent and efficacious approach to selectively deplete BCMA-positive MM cells and represents a novel immunotherapeutic for the treatment of MM.

Phase 2 study of tabalumab, a human anti-B-cell activating factor antibody, with bortezomib and dexamethasone in patients with previously treated multiple myeloma

In this double-blind, Phase 2 study, 220 patients with relapsed/refractory multiple myeloma were randomly assigned 1:1:1 to receive placebo (N = 72), tabalumab 100 mg (N = 74), or tabalumab 300 mg (N = 74), each in combination with dexamethasone 20 mg and subcutaneous bortezomib 1·3 mg/m² on a 21-day cycle. No significant intergroup differences were observed among primary (median progression-free survival [mPFS]) or secondary efficacy outcomes. The mPFS was 6·6, 7·5 and 7·6 months for the tabalumab 100, 300 mg and placebo groups, respectively (tabalumab 100 mg vs. placebo Hazard ratio (HR) [95% confidence interval (CI)] = 1·13 [0·80-1·59], P = 0·480; tabalumab 300 mg vs. placebo HR [95% CI] = 1·03 [0·72-1·45], P = 0·884). The most commonly-reported treatment-emergent adverse events were thrombocytopenia (37%), fatigue (37%), diarrhoea (35%) and constipation (32%). Across treatments, patients with low baseline BAFF (also termed TNFSF13B) expression (n = 162) had significantly longer mPFS than those with high BAFF expression (n = 55), using the 75th percentile cut-off point (mPFS [95% CI] = 8·3 [7·0-9·3] months vs. 5·8 [3·7-6·6] months; HR [95% CI] = 1·59 [1·11-2·29], P = 0·015). Although generally well tolerated, PFS was not improved during treatment with tabalumab compared to placebo. A higher dose of 300 mg tabalumab did not improve efficacy compared to the 100 mg dose. Nonetheless, BAFF appears to have some prognostic value in patients with multiple myeloma.

Integration of Novel Agents into the Care of Patients with Multiple Myeloma

The pace of therapeutic drug development in multiple myeloma has reached unprecedented levels, with five regulatory approvals for relapsed and/or refractory disease of either new drugs or new drug regimens in 2015, one already in 2016, and still others anticipated. This has provided a wide array of options to be considered by patients and their health care providers in the event of relapse after or progression on front-line therapy. Most of these agents are currently being evaluated in earlier patient populations, including as parts of induction, consolidation, and maintenance therapy approaches, where their benefits may be even greater. Moreover, additional randomized studies have been completed with our previous stable of novel agents that inform their use in these settings as well. In the current contribution to this CCR Focus on multiple myeloma, we will present an overview of some of the key recent data that have supported the addition of these new therapeutics to our armamentarium against multiple myeloma. Also, we will provide some guidelines about possible best practices in applying these regimens and attempt to extrapolate how they will be used as parts of our future standards of care. Clin Cancer Res; 22(22); 5443-52. ©2016 AACR SEE ALL ARTICLES IN THIS CCR FOCUS SECTION, "MULTIPLE MYELOMA MULTIPLYING THERAPIES".

Spotlight on elotuzumab in the treatment of multiple myeloma: the evidence to date

Despite advances in the treatment of multiple myeloma, it remains an incurable disease, with relapses and resistances frequently observed. Recently, immunotherapies, in particular, monoclonal antibodies, have become important treatment options in anticancer therapies. Elotuzumab is a humanized monoclonal antibody to signaling lymphocytic activation molecule F7, which is highly expressed on myeloma cells and, to a lower extent, on selected leukocyte subsets such as natural killer cells. By directly activating natural killer cells and by antibody-dependent cell-mediated cytotoxicity, elotuzumab exhibits a dual mechanism of action leading to myeloma cell death with minimal effects on normal tissue. In several nonclinical models of multiple myeloma, elotuzumab was effective as a single agent and in combination with standard myeloma treatments, supporting the use of elotuzumab in patients. In combination with lenalidomide and dexamethasone, elotuzumab showed a significant increase in tumor response rates and progression-free survival in patients with relapsed and/or refractory multiple myeloma. This review summarizes the nonclinical and clinical development of elotuzumab as a single agent and in combination with established therapies for the treatment of multiple myeloma.

Alectinib, Ceritinib, Elotuzumab, and Venetoclax

The complexity of cancer chemotherapy requires pharmacists be familiar with the complicated regimens and highly toxic agents used. This column reviews various issues related to preparation, dispensing, and administration of antineoplastic therapy, and the agents, both commercially available and investigational, used to treat malignant diseases. Questions or suggestions for topics should be addressed to Dominic A. Solimando, Jr, President, Oncology Pharmacy Services, Inc., 4201 Wilson Blvd #110-545, Arlington, VA 22203, e-mail: OncRxSvc@comcast.net; or J. Aubrey Waddell, Professor, University of Tennessee College of Pharmacy; Oncology Pharmacist, Pharmacy Department, Blount Memorial Hospital, 907 E. Lamar Alexander Parkway, Maryville, TN 37804, e-mail: waddfour@charter.net.

The next generation of novel therapies for the management of relapsed multiple myeloma

The advent of various novel therapies such as immunomodulators and proteasome inhibitors has transformed the treatment paradigm for patients with multiple myeloma (MM). As a result, the overall survival has improved dramatically over the last decade. Despite these advances, MM remains mostly incurable and most patients experience disease relapse after enjoying a period of disease control or remission. Fortunately, the scientific community continues to make strides in developing 'next-generation' therapies for the management of patients with relapsed MM. This review will summarize the efficacy of some of the newest therapeutic agents available for the treatment of patients with relapsed MM after their upfront treatment with the original novel agents such as thalidomide, lenalidomide and bortezomib.

The role of SLAMF7 in multiple myeloma: impact on therapy

INTRODUCTION

Multiple myeloma (MM), a mature B-cell neoplasm, is the second most common hematologic malignancy worldwide. Despite significant improvements in outcome with new therapies, the majority of responding patients will eventually develop resistance to treatment. Furthermore, patients swith disease refractory to both proteasome inhibitors and immunomodulatory drugs (IMiDs) have a poor prognosis. Areas covered: Several new therapeutic approaches are emerging and immunotherapeutic strategies present an important advance for the treatment of patients with relapsed or refractory MM. Among the monoclonal antibodies under development in MM, those targeting SLAMF7 and CD38 have shown the most consistent benefit in trials to date. In this review, we will specifically focus on elotuzumab (anti-SLAMF7 antibody), and provide a summary of the mechanism of action, the clinical results and the safety profile of this new drug. Expert commentary: Although elotuzumab has no single agent activity in MM, randomized trials in relapsed/refractory MM have demonstrated significantly improved progression-free survival when the agent is added to bortezomib-dexamethasone or lenalidomide-dexamethasone. Furthermore, this agent with its novel mechanism of action can be combined with standard therapies without a significant increase in toxicity. Elotuzumab is a highly effective therapy and future data are necessary to identify the best place for this therapy in the setting of MM.

Elotuzumab: a novel immune-stimulating therapy to treat multiple myeloma

INTRODUCTION

Multiple myeloma (MM), constantly remains debilitating disease, consequently leading to death. Clinical trials involving drugs with different mechanisms of action, carry the expectancy for improvement of treatment outcomes. The results of the currently published studies on the monoclonal antibodies, in particular elotuzumab confirm previous expectations of improving treatment outcomes of such therapy in MM patients.

AREAS COVERED

This humanized monoclonal antibody targeting surface glycoprotein CS1, expressed commonly on plasma cells and certain cells of the immune system, stimulates the immune system to fight against MM cells. Elotuzumab in the combination with len/dex has been approved by the FDA for treatment of relapsed/refractory MM patients who have received one to three prior therapies. Expert commentary: This review summarizes the chemistry, mechanism of action and preclinical and clinical studies, pharmacodynamics, pharmacokinetics, safety and toxicity of elotuzumab in terms of MM treatment and its potential application in the future.

APRIL and BCMA promote human multiple myeloma growth and immunosuppression in the bone marrow microenvironment

Here we show that overexpression or activation of B-cell maturation antigen (BCMA) by its ligand, a proliferation-inducing ligand (APRIL), promotes human multiple myeloma (MM) progression in vivo. BCMA downregulation strongly decreases viability and MM colony formation; conversely, BCMA overexpression augments MM cell growth and survival via induction of protein kinase B (AKT), MAPK, and nuclear factor (NF)-κB signaling cascades. Importantly, BCMA promotes in vivo growth of xenografted MM cells harboring p53 mutation in mice. BCMA-overexpressing tumors exhibit significantly increased CD31/microvessel density and vascular endothelial growth factor compared with paired control tumors. These tumors also express increased transcripts crucial for osteoclast activation, adhesion, and angiogenesis/metastasis, as well as genes mediating immune inhibition including programmed death ligand 1, transforming growth factor β, and interleukin 10. These target genes are consistently induced by paracrine APRIL binding to BCMA on MM cells, which is blocked by an antagonistic anti-APRIL monoclonal antibody hAPRIL01A (01A). 01A is cytotoxic against MM cells even in the presence of protective bone marrow (BM) myeloid cells including osteoclasts, macrophages, and plasmacytoid dendritic cells. 01A further decreases APRIL-induced adhesion and migration of MM cells via blockade of canonical and noncanonical NF-κB pathways. Moreover, 01A prevents in vivo MM cell growth within implanted human bone chips in SCID mice. Finally, the effect of 01A on MM cell viability is enhanced by lenalidomide and bortezomib. Taken together, these data delineate new molecular mechanisms of in vivo MM growth and immunosuppression critically dependent on BCMA and APRIL in the BM microenvironment, further supporting targeting this prominent pathway in MM.

Monoclonal antibodies - A new era in the treatment of multiple myeloma

Monoclonal antibodies (mAbs) are currently the most investigated therapeutic compounds in oncology, but there is no monoclonal antibody approved in the treatment of multiple myeloma (MM). Nevertheless several really promising molecules are under investigation in phase III clinical trials. Dominantly daratumumab (anti-CD38) and elotuzumab (anti-CS1) showed extraordinary effectiveness in phase I/II trials. The toxicity was acceptable which is important for their addition to standard anti-myeloma agents like proteasome inhibitors or immunomodulatory drugs. Monoclonal antibodies such as denosumab (anti-RANKL) or BHQ880 (anti-DKK-1) are investigated also in the management of myeloma bone disease. This review is focused on the most promising mAbs, their mechanisms of action and the rationale of use. Practically all available results have been described. If the ongoing trials confirm the efficacy and safety of mAbs, they would become an important part of MM treatment that would be translated in the further improvement of therapeutic outcomes.