Marrow stromal cells induce B7-H1 expression on myeloma cells, generating aggressive characteristics in multiple myeloma

Peptide Vaccination Against PD-L1 With IO103 a Novel Immune Modulatory Vaccine in Multiple Myeloma: A Phase I First-in-Human Trial

Background

Immune checkpoint blockade with monoclonal antibodies targeting programmed death 1 (PD-1) and its ligand PD-L1 has played a major role in the rise of cancer immune therapy. We have identified naturally occurring self-reactive T cells specific to PD-L1 in both healthy donors and cancer patients. Stimulation with a PD-L1 peptide (IO103), activates these cells to exhibit inflammatory and anti-regulatory functions that include cytotoxicity against PD-L1-expressing target cells. This prompted the initiation of the present first-in-human study of vaccination with IO103, registered at clinicaltrials.org (NCT03042793).

Methods

Ten patients with multiple myeloma who were up to 6 months after high dose chemotherapy with autologous stem cell support, were enrolled. Subcutaneous vaccinations with IO103 with the adjuvant Montanide ISA 51 was given up to fifteen times during 1 year. Safety was assessed by the common toxicity criteria for adverse events (CTCAE). Immunogenicity of the vaccine was evaluated using IFNγ enzyme linked immunospot and intracellular cytokine staining on blood and skin infiltrating lymphocytes from sites of delayed-type hypersensitivity. The clinical course was described.

Results

All adverse reactions to the PD-L1 vaccine were below CTCAE grade 3, and most were grade 1-2 injection site reactions. The total rate of adverse events was as expected for the population. All patients exhibited peptide specific immune responses in peripheral blood mononuclear cells and in skin-infiltrating lymphocytes after a delayed-type hypersensitivity test. The clinical course was as expected for the population. Three of 10 patients had improvements of responses which coincided with the vaccinations.

Conclusion

Vaccination against PD-L1 was associated with low toxicity and high immunogenicity. This study has prompted the initiation of later phase trials to assess the vaccines efficacy.

Clinical Trial Registration

clinicaltrials.org, identifier NCT03042793.

Regulation of PD-L1 expression in K-ras-driven cancers through ROS-mediated FGFR1 signaling

K-ras mutations are major genetic events that drive cancer development associated with aggressive malignant phenotypes, while expression of the immune checkpoint molecule PD-L1 plays a key role in cancer evasion of the immune surveillance that also profoundly affects the patient outcome. However, the relationship between K-ras oncogenic signal and PD-L1 expressions as an important area that requires further investigation. Using both in vitro and in vivo experimental models of K-ras-driven cancer, we found that oncogenic K-ras significantly enhanced PD-L1 expression through a redox-mediated mechanism. Activation of K-ras^G12V promoted ROS generation and induced FGFR1 expression, leading to a significant upregulation of PD-L1. We further showed that exogenous ROS such as hydrogen peroxide alone was sufficient to activate FGFR1 and induce PD-L1, while antioxidants could largely abrogate PD-L1 expression in K-ras mutant cells, indicating a critical role of redox regulation. Importantly, genetic knockout of FGFR1 led to a decrease in PD-L1 expression, and impaired tumor growth in vivo due to a significant increase of T cell infiltration in the tumor tissues and thus enhanced T-cell-mediated tumor suppression.

Our study has identified a novel mechanism by which K-ras promotes PD-L1 expression, and suggests that modulation of ROS or inhibition of the FGFR1 pathway could be a novel strategy to abrogate PD-L1-mediated immunosuppression and thus potentially improve the efficacy of immunotherapy in K-ras-driven cancers.

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Oncogenic K-Ras up-regulates PD-L1 expression in vitro and in vivo.

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ROS play a major role in mediating K-Ras-induced FGFR1 activation leading to PD-L1 expression in K-Ras-driven cancers.

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Antioxidants are able to modulate PD-L1 expression in K-Ras mutant cancer cells.

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Suppression of FGFR1 enhances CD8⁺ T cell infiltration and inhibits tumor growth.

Actors on the Scene: Immune Cells in the Myeloma Niche

Two mechanisms are involved in the immune escape of cancer cells: the immunoediting of tumor cells and the suppression of the immune system. Both processes have been revealed in multiple myeloma (MM). Complex interactions between tumor plasma cells and the bone marrow (BM) microenvironment contribute to generate an immunosuppressive milieu characterized by high concentration of immunosuppressive factors, loss of effective antigen presentation, effector cell dysfunction, and expansion of immunosuppressive cell populations, such as myeloid-derived suppressor cells, regulatory T cells and T cells expressing checkpoint molecules such as programmed cell death 1. Considering the great immunosuppressive impact of BM myeloma microenvironment, many strategies to overcome it and restore myeloma immunosurveillance have been elaborated. The most successful ones are combined approaches such as checkpoint inhibitors in combination with immunomodulatory drugs, anti-monoclonal antibodies, and proteasome inhibitors as well as chimeric antigen receptor (CAR) T cell therapy. How best to combine anti-MM therapies and what is the optimal timing to treat the patient are important questions to be addressed in future trials. Moreover, intratumor MM heterogeneity suggests the crucial importance of tailored therapies to identify patients who might benefit the most from immunotherapy, reaching deeper and more durable responses.

Quantifying PD-L1 Expression to Monitor Immune Checkpoint Therapy: Opportunities and Challenges

Simple Summary

Malignant cells hijack the regulatory roles of immune checkpoint proteins for immune evasion and survival. Therapeutics blocking those proteins can restore the balance of the immune system and lead to durable responses in cancer patients. Although a subset of patients derive benefit, there are few non-invasive technologies to guide and monitor those therapies to improve success rates. This is a review of the advancements in non-invasive methods for quantification of immune checkpoint protein programmed death ligand 1 expression, a biomarker detected by immunohistochemistry and widely used for guiding immune checkpoint therapy.

Abstract

Therapeutics targeting programmed death ligand 1 (PD-L1) protein and its receptor PD-1 are now dominant players in restoring anti-tumor immune responses. PD-L1 detection by immunohistochemistry (IHC) is emerging as a reproducible biomarker for guiding patient stratification for those therapies in some cancers. However, PD-L1 expression in the tumor microenvironment is highly complex. It is upregulated by aberrant genetic alterations, and is highly regulated at the transcriptional, posttranscriptional, and protein levels. Thus, PD-L1 IHC is inadequate to fully understand the relevance of PD-L1 levels in the whole body and their dynamics to improve therapeutic outcomes. Imaging technologies could potentially assist in meeting that need. Early clinical investigations show promising results in quantifying PD-L1 expression in the whole body by positron emission tomography (PET). Within this context, this review summarizes advancements in regulation of PD-L1 expression and imaging agents, and in PD-L1 PET for drug development, and discusses opportunities and challenges presented by these innovations for guiding immune checkpoint therapy (ICT).

Molecular mechanisms of breast cancer chemoresistance by immune checkpoints

Progression of resistance to chemotherapy in breast cancer (BC) has been recognized as a main factor in decreasing the survival of patients with this malignancy. Recent investigations have described the involvement of immune checkpoint molecules in the progress of drug resistance in breast carcinoma patients. In the present study, the molecular participation of immune checkpoint factors in chemoresistance of BC both in-vitro and in-vivo is reviewed. Numerous immune checkpoints such as PD-1/PD-L1, CTLA-4, B7-H3, B7-H4, B7-1, and B7-2 have been specified as positive regulators of resistance to various drug types in BC. In several molecular pathways of drug resistance in BC, immune checkpoints affect the chemoresistance of this cancer in a drug- and cell-type-dependent manner. In addition, immune checkpoints promote chemoresistance in response to particular drugs in specific BC cell lines. Furthermore, several the immune checkpoint molecules have not been evaluated in the field of the chemoresistance in breast malignancy either in-vitro or in-vivo. Overall, investigations have indicated that targeting immune checkpoint molecules may be considered as a novel method to improve existing anti-BC treatments.

Pembrolizumab plus lenalidomide and dexamethasone in treatment-naive multiple myeloma (KEYNOTE-185): subgroup analysis in Japanese patients

The global, randomized, open-label KEYNOTE-185 study closed early after an interim analysis showed an unfavorable benefit-risk profile with pembrolizumab plus lenalidomide and low-dose dexamethasone (Rd) versus Rd alone in treatment-naive, transplant-ineligible multiple myeloma. This subgroup analysis reported outcomes in the Japanese population. Patients were randomly assigned (1:1) to pembrolizumab plus Rd or Rd alone, stratified by age and International Staging System. The primary end point was progression-free survival (PFS). Fifty-two Japanese patients were randomly assigned to pembrolizumab plus Rd (n = 27) or Rd (n = 25). The median follow-up was 7.2 months (range, 0.4-13.8). The median PFS was not reached (NR); 6-month PFS was 91.2% versus 86.2% with pembrolizumab plus Rd versus Rd [hazard ratio (HR), 0.31; 95% CI, 0.06-1.63]. The median overall survival (OS) was NR; 6-month OS was 96.2% versus 95.7% with pembrolizumab plus Rd versus Rd (HR, 0.33; 95% CI, 0.03-3.72). With pembrolizumab plus Rd versus Rd, grade 3-5 adverse events occurred in 70.4% versus 69.6% of patients; serious adverse events occurred in 40.7% versus 52.5%. Although in the Japanese subgroup of KEYNOTE-185 adding pembrolizumab to Rd did not show an unfavorable risk-benefit, the analysis is limited by short follow-up and small sample size, affecting generalizability of the results.

The microenvironment in myeloma

PURPOSE OF REVIEW

The aim of the review is to describe recent advances in our understanding of how multiple myeloma interacts with its cellular and molecular neighbours in the bone marrow microenvironment, and how this may provide targets for prognostication and prevention.

RECENT FINDINGS

The bone marrow microenvironment in myeloma is beginning to yield targets that are amenable to therapy. A number of trials demonstrate some clinical efficacy in heavily pretreated disease. The challenge remains for how and when these therapeutic interventions are of particular benefit early in disease progression.

SUMMARY

Multiple myeloma is rarely curable and its interactions with the bone marrow microenvironment are evident. However, separating cause from effect remains a challenge. We propose that targeting specific niches within the bone marrow will yield therapies that have the potential for significant benefit in myeloma and may facilitate earlier intervention to disrupt an environment that is permissive for myeloma progression.

Latest perspectives on glucocorticoid-induced apoptosis and resistance in lymphoid malignancies

Glucocorticoids are essential drugs in the treatment protocols of lymphoid malignancies. These steroidal hormones trigger apoptosis of the malignant cells by binding to the glucocorticoid receptor (GR), which is a member of the nuclear receptor superfamily. Long term glucocorticoid treatment is limited by two major problems: the development of glucocorticoid-related side effects, which hampers patient quality of life, and the emergence of glucocorticoid resistance, which is a gradual process that is inevitable in many patients. This emphasizes the need to reevaluate and optimize the widespread use of glucocorticoids in lymphoid malignancies. To achieve this goal, a deep understanding of the mechanisms governing glucocorticoid responsiveness is required, yet, a recent comprehensive overview is currently lacking. In this review, we examine how glucocorticoids mediate apoptosis by detailing GR's genomic and non-genomic action mechanisms in lymphoid malignancies. We continue with a discussion of the glucocorticoid-related problems and how these are intertwined with one another. We further zoom in on glucocorticoid resistance by critically analyzing the plethora of proposed mechanisms and highlighting therapeutic opportunities that emerge from these studies. In conclusion, early detection of glucocorticoid resistance in patients remains an important challenge as this would result in a timelier treatment reorientation and reduced glucocorticoid-instigated side effects.

The SLAMF3 rs509749 polymorphism correlates with malignant potential in multiple myeloma

The signaling lymphocytic activation molecule family 3 (SLAMF3) is highly expressed on plasma cells from patients with multiple myeloma (MM) and induces high malignant potential by ERK signaling mediated via the interaction with adaptor proteins SHP2 and GRB2. This study focused on the single-nucleotide polymorphism (SNP) of the SLAMF3 gene (rs509749, 1804A>G, M602V) in MM. The SNP G allele was a major type, and the frequencies of the GG, GA, and AA genotypes were 61.8%, 29.4%, and 8.8%, respectively, in patients with MM, which was almost the same as in healthy the control group in the Japanese population. Interestingly, patients with GG genotypes had significantly shorter overall survival times than patients with GA/AA genotypes. Consistent with those results, SLAMF3-overexpressing KMS-34 cells with the G allele (V₆₀₂) had higher cell proliferation potential and were more resistant to anti-MM agents than those with the A allele (M₆₀₂). When those cells were subcutaneously inoculated into NOG mice, tumor sizes in mice receiving V₆₀₂ cells rapidly increased, and survival was significantly shorter than in mice injected with M₆₀₂ cells. Furthermore, SLAMF3 V₆₀₂ molecules bound more tightly to SHP2 and GRB2, with increased SHP2 and ERK phosphorylation compared with M₆₀₂ cells. The mRNA expression of cell cycle-related genes (CCND1 and CCNE1) and anti-apoptotic genes (BCL2L and p21) was increased in V₆₀₂ cells compared with M₆₀₂ cells. The results thus suggested that the G allele of SLAMF3 SNP rs509749 may be associated with MM disease progression.

PD-L1 expression in bone marrow plasma cells as a biomarker to predict multiple myeloma prognosis: developing a nomogram-based prognostic model

PD-L1 expression is associated with poor prognosis, although this relationship is unclear in bone marrow-derived haematologic malignancies, including multiple myeloma. We aimed to determine whether PD-L1 expression could predict the prognosis of newly diagnosed multiple myeloma (NDMM). We evaluated 126 NDMM patients (83, retrospectively; 43, prospectively) who underwent bone marrow examinations. Bone marrow aspirates were analysed for PD-L1 expression, categorized as low or high expression, using quantitative immunofluorescence. High PD-L1 expression could independently predict poor overall survival (OS) (95% CI = 1.692-8.346) in multivariate analysis. On subgroup analysis, high PD-L1 expression was associated with poor OS (95% CI = 2.283-8.761) and progression-free survival (95% CI = 1.024-3.484) in patients who did not undergo autologous stem cell transplantation (ASCT) compared with those who did. High PD-L1 expression was associated with poor OS despite frontline treatments with or without immunomodulators. Thus, PD-L1 expression can be a useful prognosis predictor in NDMM patients, whereas ASCT may be used in patients with high PD-L1 expression. We developed a prognostic nomogram and found that a combination of PD-L1 expression in bone marrow plasma cells and clinical parameters (age, cytogenetics, and lactate dehydrogenase) effectively predicted NDMM prognosis. We believe that our nomogram can help identify high-risk patients and select appropriate treatments.

Cytokine-Mediated Dysregulation of Signaling Pathways in the Pathogenesis of Multiple Myeloma

Multiple myeloma (MM) is a hematologic disorder of B lymphocytes characterized by the accumulation of malignant plasma cells (PCs) in the bone marrow. The altered plasma cells overproduce abnormal monoclonal immunoglobulins and also stimulate osteoclasts. The host’s immune system and microenvironment are of paramount importance in the growth of PCs and, thus, in the pathogenesis of the disease. The interaction of MM cells with the bone marrow (BM) microenvironment through soluble factors and cell adhesion molecules causes pathogenesis of the disease through activation of multiple signaling pathways, including NF-κβ, PI3K/AKT and JAK/STAT. These activated pathways play a critical role in the inhibition of apoptosis, sustained proliferation, survival and migration of MM cells. Besides, these pathways also participate in developing resistance against the chemotherapeutic drugs in MM. The imbalance between inflammatory and anti-inflammatory cytokines in MM leads to an increased level of pro-inflammatory cytokines, which in turn play a significant role in dysregulation of signaling pathways and proliferation of MM cells; however, the association appears to be inadequate and needs more research. In this review, we are highlighting the recent findings on the roles of various cytokines and growth factors in the pathogenesis of MM and the potential therapeutic utility of aberrantly activated signaling pathways to manage the MM disease.

CAMK1D Triggers Immune Resistance of Human Tumor Cells Refractory to Anti-PD-L1 Treatment

The success of cancer immunotherapy is limited by resistance to immune checkpoint blockade. We therefore conducted a genetic screen to identify genes that mediated resistance against CTLs in anti-PD-L1 treatment-refractory human tumors. Using PD-L1-positive multiple myeloma cells cocultured with tumor-reactive bone marrow-infiltrating CTL as a model, we identified calcium/calmodulin-dependent protein kinase 1D (CAMK1D) as a key modulator of tumor-intrinsic immune resistance. CAMK1D was coexpressed with PD-L1 in anti-PD-L1/PD-1 treatment-refractory cancer types and correlated with poor prognosis in these tumors. CAMK1D was activated by CTL through Fas-receptor stimulation, which led to CAMK1D binding to and phosphorylating caspase-3, -6, and -7, inhibiting their activation and function. Consistently, CAMK1D mediated immune resistance of murine colorectal cancer cells in vivo The pharmacologic inhibition of CAMK1D, on the other hand, restored the sensitivity toward Fas-ligand treatment in multiple myeloma and uveal melanoma cells in vitro Thus, rapid inhibition of the terminal apoptotic cascade by CAMK1D expressed in anti-PD-L1-refractory tumors via T-cell recognition may have contributed to tumor immune resistance.

Potent anti-myeloma efficacy of dendritic cell therapy in combination with pomalidomide and programmed death-ligand 1 blockade in a preclinical model of multiple myeloma

Dendritic cell (DC)-based vaccines are recognized as a promising immunotherapeutic strategy against cancer; however, the efficacy of immunotherapy with DCs is controlled via immune checkpoints, such as programmed death-ligand 1 (PD-L1). PD-L1 expressed on DC and tumor cells binds to programmed death-1 (PD-1) receptors on the activated T cells, which leads to the inhibition of cytotoxic T cells. Blocking of PD-L1 on DC may lead to improve the efficacy of DC therapy for cancer. Here we demonstrated that DC vaccination in combination with pomalidomide and programmed death-ligand 1 (PD-L1) blockade inhibited tumor growth of a multiple myeloma (MM) mouse model. DCs + pomalidomide with dexamethasone + PD-L1 blockade significantly inhibited immune immunosuppressive factors and promoted proportions of immune effector cells in the spleen and tumor microenvironment. Additionally, functional activities of cytotoxic T lymphocytes and NK cells in spleen were enhanced by DCs + pomalidomide with dexamethasone + PD-L1 blockade. Taken together, this study identifies a potential new therapeutic approach for the treatment of MM. These results also provide a foundation for the future development of immunotherapeutic modalities to inhibit tumor growth and restore immune function in MM.

Marrow-Infiltrating Regulatory T Cells Correlate with the Presence of Dysfunctional CD4+PD-1+ Cells and Inferior Survival in Patients with Newly Diagnosed Multiple Myeloma

PURPOSE

Immune dysregulation is described in multiple myeloma. While preclinical models suggest a role for altered T-cell immunity in disease progression, the contribution of immune dysfunction to clinical outcomes remains unclear. We aimed to characterize marrow-infiltrating T cells in newly diagnosed patients and explore associations with outcomes of first-line therapy.

EXPERIMENTAL DESIGN

We undertook detailed characterization of T cells from bone marrow (BM) samples, focusing on immune checkpoints and features of immune dysfunction, correlating with clinical features and progression-free survival.

RESULTS

We found that patients with multiple myeloma had greater abundance of BM regulatory T cells (Tregs) which, in turn, expressed higher levels of the activation marker CD25 compared with healthy donors. Patients with higher frequencies of Tregs had shorter PFS and a distinct Treg immune checkpoint profile (increased PD-1, LAG-3) compared with patients with lower frequencies of Tregs. Analysis of CD4 and CD8 effectors revealed that low CD4effector (CD4eff):Treg ratio and increased frequency of PD-1-expressing CD4eff cells were independent predictors of early relapse over and above conventional risk factors, such as genetic risk and depth of response. Ex vivo functional analysis and RNA sequencing revealed that CD4 and CD8 cells from patients with greater abundance of CD4effPD-1+ cells displayed transcriptional and secretory features of dysfunction.

CONCLUSIONS

BM-infiltrating T-cell subsets, specifically Tregs and PD-1-expressing CD4 effectors, negatively influence clinical outcomes in newly diagnosed patients. Pending confirmation in larger cohorts and further mechanistic work, these immune parameters may inform new risk models, and present potential targets for immunotherapeutic strategies.

Checkpoint Inhibitors and Engineered Cells: New Weapons for Natural Killer Cell Arsenal Against Hematological Malignancies

Natural killer (NK) cells represent one of the first lines of defense against malignant cells. NK cell activation and recognition are regulated by a balance between activating and inhibitory receptors, whose specific ligands can be upregulated on tumor cells surface and tumor microenvironment (TME). Hematological malignancies set up an extensive network of suppressive factors with the purpose to induce NK cell dysfunction and impaired immune-surveillance ability. Over the years, several strategies have been developed to enhance NK cells-mediated anti-tumor killing, while other approaches have arisen to restore the NK cell recognition impaired by tumor cells and other cellular components of the TME. In this review, we summarize and discuss the strategies applied in hematological malignancies to block the immune check-points and trigger NK cells anti-tumor effects through engineered chimeric antigen receptors.

Resistance mechanisms to immune checkpoints blockade by monoclonal antibody drugs in cancer immunotherapy: Focus on myeloma

Multiple myeloma (MM) is a clonal B-cell malignancy characterized by the accumulation of neoplastic proliferation of a plasma cell in the bone marrow that produces a monoclonal immunoglobulin. The immune checkpoint inhibitors against programmed death-1/programmed death-1 ligand and cytotoxic T-lymphocyte antigen 4 axis have demonstrated appropriate anticancer activity in several solid tumors and liquid cancers, and are rapidly transforming the practice of medical oncology. However, in a high percentage of patients, the efficacy of immune checkpoints blockade remains limited due to innate or primary resistance. Moreover, the malignancies progress in many patients due to acquired or secondary resistance, even after the clinical response to immune checkpoints' blockade. The evidence shows that multiple tumor-intrinsic and tumor-extrinsic factors and alterations in signaling pathways are involved in primary and secondary resistance to immune checkpoints blockade. Improved identification of intrinsic and extrinsic factors and mechanisms of resistance or response to immune checkpoints blockade may not only provide novel prognostic or predictive biomarkers but also guide the optimal combination/sequencing of immune checkpoint blockade therapy in the clinic. Here, we review the underlying biology and role of immune checkpoints blockade in patients with MM. Furthermore, we review the host and tumor-related factor effects on immune checkpoints blockade in MM immunotherapy.

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

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

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.

Genomic Instability in Multiple Myeloma

Genomic instability (GIN), an increased tendency to acquire genomic alterations, is a cancer hallmark. However, its frequency, underlying causes, and disease relevance vary across different cancers. Multiple myeloma (MM), a plasma cell malignancy, evolves through premalignant phases characterized by genomic abnormalities. Next-generation sequencing (NGS) methods are deconstructing the genomic landscape of MM across the continuum of its development, inextricably linking malignant transformation and disease progression with increasing acquisition of genomic alterations, and illuminating the mechanisms that generate these alterations. Although GIN drives disease evolution, it also creates vulnerabilities such as dependencies on 'superfluous' repair mechanisms and the induction of tumor-specific antigens that can be targeted. We review the mechanisms of GIN in MM, the associated vulnerabilities, and therapeutic targeting strategies.

Identification of the immune checkpoint signature of multiple myeloma using mass cytometry-based single-cell analysis

Objectives

New targets or strategies are needed to increase the success of immune checkpoint-based immunotherapy for multiple myeloma (MM). However, immune checkpoint signals in MM microenvironment have not been fully elucidated. Here, we aimed to have a broad overview of the different immune subsets and their immune checkpoint status, within the MM microenvironment, and to provide novel immunotherapeutic targets to treat MM patients.

Methods

We performed immune checkpoint profiling of bone marrow (BM) samples from MM patients and healthy controls using mass cytometry. With high-dimensional single-cell analysis of 30 immune proteins containing 10 pairs of immune checkpoint axes in 0.55 million of BM cells, an immune landscape of MM was mapped.

Results

We identified an abnormality of immune cell composition by demonstrating a significant increase in activated CD4 T, CD8 T, CD8⁺ natural killer T-like and NK cells in MM BM. Our data suggest a correlation between MM cells and immune checkpoint phenotypes and expand the view of MM immune signatures. Specifically, several critical immune checkpoints, such as programmed cell death 1 (PD-1)/PD ligand 2, galectin-9/T-cell immunoglobulin mucin-3, and inducible T-cell costimulator (ICOS)/ICOS ligand, on both MM and immune effector cells and a number of activated PD-1⁺ CD8 T cells lacking CD28 were distinguished in MM patients.

Conclusion

A clear interaction between MM cells and the surrounding immune cells was established, leading to immune checkpoint dysregulation. The analysis of the immune landscape enhances our understanding of the MM immunological milieu and proposes novel targets for improving immune checkpoint blockade-based MM immunotherapy.

Challenges for Immunotherapy in Multiple Myeloma: Bone Marrow Microenvironment-Mediated Immune Suppression and Immune Resistance

The power of immunotherapy in the battle of Multiple Myeloma (MM) started with allogeneic stem cell transplantation, and was rediscovered with immunomodulatory drugs and extended with the outstanding results achieved with targeted antibodies. Today, next to powerful antibodies Elotuzumab and Daratumumab, several T-cell-based immunotherapeutic approaches, such as bispecific antibodies and chimeric antigen receptor-transduced T-cells (CAR T-cells) are making their successful entry in the immunotherapy arena with highly promising results in clinical trials. Nonetheless, similar to what is observed in chemotherapy, MM appears capable to escape from immunotherapy, especially through tight interactions with the cells of the bone marrow microenvironment (BM-ME). This review will outline our current understanding on how BM-ME protects MM-cells from immunotherapy through immunosuppression and through induction of intrinsic resistance against cytotoxic effector mechanisms of T- and NK-cells.

PD-L1-PD-1 Pathway in the Pathophysiology of Multiple Myeloma

PD-L1 expressed on tumor cells contributes to disease progression with evasion from tumor immunity. Plasma cells from multiple myeloma (MM) patients expressed higher levels of PD-L1 compared with healthy volunteers and monoclonal gammopathy of undetermined significance (MGUS) patients, and its expression is significantly upregulated in relapsed/refractory patients. Furthermore, high PD-L1 expression is induced by the myeloma microenvironment and PD-L1⁺ patients with MGUS and asymptomatic MM tend to show disease progression. PD-L1 expression on myeloma cells was associated with more proliferative potential and resistance to antimyeloma agents because of activation of the Akt pathway through PD-1-bound PD-L1 in MM cells. Those data suggest that PD-L1 plays a crucial role in the disease progression of MM.

NK and NKT Cell-Mediated Immune Surveillance against Hematological Malignancies

Recent cancer treatment modalities have been intensively focused on immunotherapy. The success of chimeric antigen receptor T cell therapy for treatment of refractory B cell acute lymphoblastic leukemia has pushed forward research on hematological malignancies. Among the effector types of innate lymphocytes, natural killer (NK) cells show great importance in immune surveillance against infectious and tumor diseases. Particularly, the role of NK cells has been argued in either elimination of target tumor cells or escape of tumor cells from immune surveillance. Therefore, an NK cell activation approach has been explored. Recent findings demonstrate that invariant natural killer T (iNKT) cells capable of producing IFN-γ when optimally activated can promptly trigger NK cells. Here, we review the role of NKT and/or NK cells and their interaction in anti-tumor responses by highlighting how innate immune cells recognize tumors, exert effector functions, and amplify adaptive immune responses. In addition, we discuss these innate lymphocytes in hematological disorders, particularly multiple myeloma and acute myeloid leukemia. The immune balance at different stages of both diseases is explored in light of disease progression. Various types of innate immunity-mediated therapeutic approaches, recent advances in clinical immunotherapies, and iNKT-mediated cancer immunotherapy as next-generation immunotherapy are then discussed.

A critical evaluation of pembrolizumab in addition to lenalidomide and dexamethasone for the treatment of multiple myeloma

Introduction: Several modalities of immunotherapy have proved successful in multiple myeloma, including immunomodulatory agents, monoclonal antibodies directed to plasma cell surface antigens and chimeric antigen receptor T cells. The PD-1 pathway is implicated in the progression of multiple myeloma. Several properties of lenalidomide are potentially synergistic with PD-1/PD-L1 blockade.Areas covered: Preclinical data related to anti-PD-1/PD-L1 antibodies and the results of early clinical trials of pembrolizumab single-agent and in combination with lenalidomide and dexamethasone are discussed. Despite promising preliminary data, the pivotal phase III trial evaluating lenalidomide and dexamethasone in combination with pembrolizumab in patients with newly diagnosed multiple myeloma presented unexpected safety findings and was discontinued. Differences with previous results and the findings of other trials involving pomalidomide as an immunomodulatory agent or nivolumab as anti-PD-1 antibody are discussed.Expert opinion: Disappointing efficacy outcomes of the combination of checkpoint blockade antibodies and immunomodulating agents in multiple myeloma along with toxicity issues make the combination unattractive in comparison with available alternatives. It is essential to critically review preclinical and clinical datha to understand the pitfalls of lenalidomide with pembrolizumab and similar combinations in multiple myeloma to gain insight on the future role of anti-PD-1 agents in emerging therapeutic scenarios.

Frequent methylation of the tumour suppressor miR-1258 targeting PDL1: implication in multiple myeloma-specific cytotoxicity and prognostification

miR-1258 is localised to the first intron of ZNF385B at chromosome 2q31.3. miR-1258 promoter methylation was studied in 147 samples including 10 normal buffy coat, eight normal bone marrow plasma cells, 16 human myeloma cell lines (HMCLs), 20 MGUS, 63 diagnostic myeloma, and 30 relapsed myeloma samples by methylation-specific PCR. In myeloma lines, miR-1258 methylation, verified by pyrosequencing, was detected in 62·5% HMCLs but not normal controls, and expression of miR-1258 correlated with that of ZNF385B. 5-Aza-2'-deoxycytidine resulted in promoter demethylation and ZNF385B/miR-1258 re-expression. Luciferase assay confirmed programmed cell death ligand-1 (PDL1) as a direct target of miR-1258. Over-expression of miR-1258 in completely methylated myeloma cells led to reduced cellular proliferation and enhanced apoptosis, hence a tumour suppressor role, in addition to repression of PDL1. In primary samples, miR-1258 methylation, with lower expression of miR-1258, was detected in 49·2% diagnostic myeloma, imparting an inferior PFS (P = 0·034) in addition to 50·0% relapsed myeloma but not MGUS. Therefore, miR-1258 is a tumour suppressor miRNA co-regulated with its host gene, and frequently hypermethylated in active myeloma instead of MGUS, hence acquired during myeloma progression. Methylation-mediated miR-1258 silencing led to overexpression of PDL1 and inferior PFS, implicating miR-1258 in the modulation of myeloma-specific cytotoxicity.

PDCD1 and PDCD1LG1 polymorphisms affect the susceptibility to multiple myeloma

Single-nucleotide polymorphisms (SNPs) of the programmed cell death protein-1 (PDCD1), programmed cell death protein-1 ligand-1 (PDCD1LG1), and cytotoxic T lymphocyte-associated antigen-4 (CTLA4) genes are implicated in the pathogenesis of some cancers. We investigated the role of PDCD1, PDCD1LG1, and CTLA4 SNPs in MM pathogenesis and the susceptibility to and clinical features of multiple myeloma (MM). We obtained genomic DNA from 124 patients with MM and 211 healthy controls and detected PDCD1 (rs36084323, rs41386349, and rs2227982), PDCD1LG1 (rs2297136 and rs4143815), and CTLA4 (rs733618, rs11571316, rs231775, and rs3087243) genotypes using the polymerase chain reaction-restriction fragment length polymorphism method or the TaqMan allelic discrimination real-time PCR method. The patients with MM had a significantly higher frequency of the PDCD1 GCC/GCC haplotype (rs36084323/rs41386349/rs2227982) compared with the healthy controls. PDCD1 rs2227982 CC genotype was associated significantly with a higher frequency of bone lesions. Patients with PDCD1LG1 rs2297136 TT and TC types (high-expression types) showed lower albumin level than those with CC genotype. In addition, the PDCD1LG1 rs4143815 CC and CG types (high-expression types) were associated significantly with higher frequency of patients who were treated with thalidomide and/or bortezomib. However, there was no statistical significance between CTLA4 polymorphisms and clinical variables of patients with MM. There were no significant differences between all the polymorphisms and OS. Our study indicates that the PDCD1 haplotype is associated with a susceptibility to MM. The PDCD1 rs2227982 and PDCD1LG1 rs2297136 affect the clinical features of multiple myeloma patients.

Daratumumab prevents programmed death ligand-1 expression on antigen-presenting cells in de novo multiple myeloma

Background

Daratumumab (Dara), an anti‐CD38 monoclonal antibody, has an immunologic mechanism of action through targeting of CD38 expressing immune cells in patients with multiple myeloma (MM). Furthermore, it was recently shown that CD38 upregulation in tumors, is a major mechanism of acquired resistance to antiprogrammed cell death 1 (PD‐1)/programmed cell death ligand 1 (PD‐L1). Therefore, we decided to evaluate the immunomodulatory effects of CD38 blockade by Dara on the PD‐L1 expressing immune cells.

Methods

We analyzed CD38 and PD‐L1 expression on immune cells at different time points in 18 newly diagnosed MM receiving bortezomib, lenalidomide and dexamethasone, with or without Dara.

Results

We first confirmed that CD38 is widely expressed on immune cells, with the strongest expression on plasmacytoid dendritic cells (pDC). Furthermore, Dara induces a strong depletion of pDC in addition to the well‐known rapid depletion of natural killer cells. Finally, we found that PD‐L1 expression on antigen‐presenting cells (APC) increases with MM treatment in patients that did not received Dara, while addition of Dara prevents this increase.

Conclusion

Overall, our results suggest new mechanisms of action of Dara through depletion of pDC and prevention of PD‐L1 upregulation expression on APC. Our finding provides new evidences for development of therapeutic strategies targeting both CD38 and PD‐L1/PD‐1 pathway in patients with MM.

SLAMF3-Mediated Signaling via ERK Pathway Activation Promotes Aggressive Phenotypic Behaviors in Multiple Myeloma

The signaling lymphocytic activation molecule family 3 (SLAMF3) is a member of the immunoglobulin superfamily expressed on T, B, and natural killer cells and modulates the activation and cytotoxicity of these cells. SLAMF3 is also expressed on plasma cells from patients with multiple myeloma (MM), although its role in MM pathogenesis remains unclear. This study found that SLAMF3 is highly and constitutively expressed on MM cells regardless of disease stage and that SLAMF3 knockdown/knockout suppresses proliferative potential and increases drug-induced apoptosis with decreased levels of phosphorylated ERK protein in MM cells. SLAMF3-overexpressing MM cells promote aggressive myeloma behavior in comparison with cytoplasmic domain-truncated SLAMF3 (ΔSLAMF3) cells. SLAMF3 interacts directly with adaptor proteins SH2 domain-containing phosphatase 2 (SHP2) and growth factor receptor bound 2 (GRB2), which also interact with each other. SLAMF3 knockdown, knockout, ΔSLAMF3, and SHP2 inhibitor-treated MM cells decreased phosphorylated ERK protein levels. Finally, serum soluble SLAMF3 (sSLAMF3) levels were markedly increased in advanced MM. Patients with high levels of sSLAMF3 progressed to the advanced stage significantly more often and had shorter progression-free survival times than those with low levels. This study revealed that SLAMF3 molecules consistently expressed on MM cells transmit MAPK/ERK signals mediated via the complex of SHP2 and GRB2 by self-ligand interaction between MM cells and induce a high malignant potential in MM. Furthermore, high levels of serum sSLAMF3 may reflect MM disease progression and be a useful prognostic factor. IMPLICATIONS: SLAMF3 may be a new therapeutic target for immunotherapy and novel agents such as small-molecule inhibitors.

PD-1 Blockade Reinvigorates Bone Marrow CD8+ T Cells from Patients with Multiple Myeloma in the Presence of TGFβ Inhibitors

PURPOSE

Immune-checkpoint inhibitors have shown therapeutic efficacy in various malignant diseases. However, anti-programmed death (PD)-1 therapy has not shown clinical efficacy in multiple myeloma.

EXPERIMENTAL DESIGN

Bone marrow (BM) mononuclear cells were obtained from 77 newly diagnosed multiple myeloma patients. We examined the expression of immune-checkpoint receptors in BM CD8⁺ T cells and their functional restoration by ex vivo treatment with anti-PD-1 and TGFβ inhibitors.

RESULTS

We confirmed the upregulation of PD-1 and PD-L1 expression in CD8⁺ T cells and myeloma cells, respectively, from the BM of multiple myeloma patients. PD-1-expressing CD8⁺ T cells from the BM of multiple myeloma patients coexpressed other checkpoint inhibitory receptors and exhibited a terminally differentiated phenotype. These results were also observed in BM CD8⁺ T cells specific to myeloma antigens NY-ESO-1 and HM1.24. BM CD8⁺ T cells from multiple myeloma patients exhibited reduced proliferation and cytokine production upon T-cell receptor stimulation. However, anti-PD-1 did not increase the proliferation of BM CD8⁺ T cells from multiple myeloma patients, indicating that T-cell exhaustion in multiple myeloma is hardly reversed by PD-1 blockade alone. Intriguingly, anti-PD-1 significantly increased the proliferation of BM CD8⁺ T cells from multiple myeloma patients in the presence of inhibitors of TGFβ, which was overexpressed by myeloma cells.

CONCLUSIONS

Our findings indicate that combined blockade of PD-1 and TGFβ may be useful for the treatment of multiple myeloma.

Immunotherapy for Multiple Myeloma

Despite therapeutic advances over the past decades, multiple myeloma (MM) remains a largely incurable disease with poor prognosis in high-risk patients, and thus new treatment strategies are needed to achieve treatment breakthroughs. MM represents various forms of impaired immune surveillance characterized by not only disrupted antibody production but also immune dysfunction of T, natural killer cells, and dendritic cells, although immunotherapeutic interventions such as allogeneic stem-cell transplantation and dendritic cell-based tumor vaccines were reported to prolong survival in limited populations of MM patients. Recently, epoch-making immunotherapies, i.e., immunomodulatory drug-intensified monoclonal antibodies, such as daratumumab combined with lenalidomide and chimeric antigen receptor T-cell therapy targeting B-cell maturation antigen, have been developed, and was shown to improve prognosis even in advanced-stage MM patients. Clinical trials using other antibody-based treatments, such as antibody drug-conjugate and bispecific antigen-directed CD3 T-cell engager targeting, are ongoing. The manipulation of anergic T-cells by checkpoint inhibitors, including an anti-T-cell immunoglobulin and ITIM domains (TIGIT) antibody, also has the potential to prolong survival times. Those new treatments or their combination will improve prognosis and possibly point toward a cure for MM.

Myeloma: next generation immunotherapy

The course of multiple myeloma (MM) from initial diagnosis to a relapsed/refractory state is characterized by acquisition of drug resistance as well as progressive immunologic dysfunction. Despite this, however, a number of novel therapies that work in part or solely via immune stimulation are in development for MM, with promising early clinical results. Several new whole-cell or multiepitope vaccine approaches are demonstrating immunologic efficacy in smoldering MM or as posttherapy consolidation, with trials ongoing to see whether this translates into delayed progression or elimination of minimal residual disease. Programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) inhibition in combination with immunomodulatory drugs demonstrated excessive toxicity in randomized trials; however, antibodies targeting PD-1/PD-L1 and other checkpoint molecules continue to be explored in combination with tumor-targeted antibodies and other T cell-directed therapies. B-cell maturation antigen (BCMA) has emerged as the next big antigen target, with multiple BCMA-specific antibody-drug conjugates (ADCs) and T cell-directed bispecific antibodies/bispecific therapeutic engagers (BiTEs) entering the clinic. In initial trials, the ADC GSK2857916 and the BiTE AMG 420 have demonstrated high response rates in relapsed/refractory patients, with depth and durability of responses that may end up rivaling chimeric antigen receptor T-cell therapies. These agents have unique toxicities that require close monitoring, but they are moving forward in larger registration studies and in combination with standard MM agents. Additional ADCs and bispecific antibodies targeting BCMA and other surface antigens (eg, CD38, CD46, CD48, FcRH5, and G protein-coupled receptor, class C group 5 member D) are moving forward in phase 1 trials and may provide even more options for MM patients.

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.

Inflammation induced PD-L1-specific T cells

PD-L1-specific T cells are a natural part of the T-cell repertoire in humans. Hence, we have previously described spontaneous CD8⁺ and CD4⁺ T-cell reactivity against PD-L1 in the peripheral blood of patients with various cancers as well as in healthy donors. It is well described that the expression of the PD-L1 protein is introduced in cells by pro-inflammatory cytokines, e.g. IFN-γ. In the current study, we were able to directly link inflammation with PD-L1-specific T cells by showing that inflammatory mediators such as IFN-γ generate measurable numbers of PD-L1-specific T cells in human PBMCs as well as in in vivo models. These PD-L1-specific T cells can vigorously modulate the cell compartments of the local environment. PD-L1-specific T cells may be important for immune homeostasis by sustaining the ongoing inflammatory response by the suppression of regulatory cell function both directly and indirectly.

Pembrolizumab plus lenalidomide and dexamethasone for patients with treatment-naive multiple myeloma (KEYNOTE-185): a randomised, open-label, phase 3 trial

BACKGROUND

Lenalidomide and dexamethasone has been a standard of care in transplant-ineligible patients with newly diagnosed multiple myeloma. The addition of a third drug to the combination is likely to improve treatment efficacy. KEYNOTE-185 assessed the efficacy and safety of lenalidomide and dexamethasone with and without pembrolizumab in patients with previously untreated multiple myeloma. Here, we present the results of an unplanned interim analysis done to assess the benefit-risk of the combination at the request of the US Food and Drug Administration (FDA).

METHODS

KEYNOTE-185 was a randomised, open-label, phase 3 trial done at 95 medical centres across 15 countries (Australia, Canada, France, Germany, Ireland, Israel, Italy, Japan, New Zealand, Norway, Russia, South Africa, Spain, UK, and USA). Transplantation-ineligible patients aged 18 years and older with newly diagnosed multiple myeloma, Eastern Cooperative Oncology Group performance status of 0 or 1, and who were treatment naive were enrolled, and randomly assigned 1:1 to receive either pembrolizumab plus lenalidomide and dexamethasone or lenalidomide and dexamethasone alone using an interactive voice or integrated web response system. Patients received oral lenalidomide 25 mg on days 1-21 and oral dexamethasone 40 mg on days 1, 8, 15, and 22 of repeated 28-day cycles, with or without intravenous pembrolizumab 200 mg every 3 weeks. The primary endpoint was progression-free survival, which was investigator-assessed because of early trial termination. Efficacy was analysed in all randomly assigned patients and safety was analysed in all patients who received at least one dose of study drug. This trial is registered at ClinicalTrials.gov, number NCT02579863, and it is closed for accrual.

FINDINGS

Between Jan 7, 2016, and June 9, 2017, 301 patients were randomly assigned to the pembrolizumab plus lenalidomide and dexamethasone group (n=151) or the lenalidomide and dexamethasone group (n=150). On July 3, 2017, the FDA decided to halt the study because of the imbalance in the proportion of death between groups. At database cutoff (June 2, 2017), with a median follow-up of 6·6 months (IQR 3·4-9·6), 149 patients in the pembrolizumab plus lenalidomide and dexamethasone group and 145 in the lenalidomide and dexamethasone group had received their assigned study drug. Median progression-free survival was not reached in either group; progression-free survival estimates at 6-months were 82·0% (95% CI 73·2-88·1) versus 85·0% (76·8-90·5; hazard ratio [HR] 1·22; 95% CI 0·67-2·22; p=0·75). Serious adverse events were reported in 81 (54%) patients in the pembrolizumab plus lenalidomide and dexamethasone group versus 57 (39%) patients in the lenalidomide and dexamethasone group; the most common serious adverse events were pneumonia (nine [6%]) and pyrexia (seven [5%]) in the pembrolizumab plus lenalidomide and dexamethasone group and pneumonia (eight [6%]) and sepsis (two [1%]) in the lenalidomide and dexamethasone group. Six (4%) treatment-related deaths occurred in the pembrolizumab plus lenalidomide and dexamethasone group (cardiac arrest, cardiac failure, myocarditis, large intestine perforation, pneumonia, and pulmonary embolism) and two (1%) in the lenalidomide and dexamethasone group (upper gastrointestinal haemorrhage and respiratory failure).

INTERPRETATION

The results from this unplanned, FDA-requested, interim analysis showed that the benefit-risk profile of pembrolizumab plus lenalidomide and dexamethasone is unfavourable for patients with newly diagnosed, previously untreated multiple myeloma. Long-term safety and survival follow-up is ongoing.

FUNDING

Merck Sharp & Dohme, a subsidiary of Merck & Co, Inc (Kenilworth, NJ, USA).

High PD-L1 Expression Predicts for Worse Outcome of Leukemia Patients with Concomitant NPM1 and FLT3 Mutations

Compared to solid tumors, the role of PD-L1 in hematological malignancies is less explored, and the knowledge in this area is mostly limited to lymphomas. However, several studies indicated that PD-L1 is also overexpressed in myeloid malignancies. Successful treatment of the acute myeloid leukemia (AML) is likely associated with elimination of the residual disease by the immune system, and possible involvement of PD-L1 in this process remains to be elucidated. We analyzed PD-L1 expression on AML primary cells by flow cytometry and, in parallel, transcript levels were determined for the transcription variants v1 and v2. The ratio of v1/v2 cDNA correlated with the surface protein amount, and high v1/v2 levels were associated with worse overall survival (p = 0.0045). The prognostic impact of PD-L1 was limited to AML with mutated nucleophosmin and concomitant internal tandem duplications in the FLT3 gene (p less than 0.0001 for this particular AML subgroup).

PD-L1, LAG3, and HLA-DR are increasingly expressed during smoldering myeloma progression

Symptomatic multiple myeloma (MM) is a plasma cell neoplasm that represents the final stage of a continuum of clinical conditions that start from monoclonal gammopathy of unknown significance (MGUS), then transits in the more advance, but still asymptomatic, smoldering MM (SMM), with a final evolution in symptomatic MM. To investigate SMM microenvironment modifications, we studied 16 patients diagnosed at our hospital. Eight of them (group A) developed MM within 2 years from diagnosis while the others (group B) had stable SMM. Samples were bone marrow biopsies at diagnosis and after 2 years (± 4 months) and were analyzed by immunohistochemical analysis. Firstly, we found a significant increase in both CD4+ cells (11 vs 17%, p < 0.01) and CD8+ cells (15 vs 18%, p < 0.01) between diagnosis and at follow-up samples (whole cohort). This was associated to an increase in the CD4+/CD8+ ratio (0.74 vs 0.93, p < 0.01). Secondly, we discovered an increased expression of T cell inhibitory molecules during SMM evolution. In fact, plasma cell PD-L1 and microenvironment cell LAG3 expression increased from 1 to 12% (p = 0.03) and 4 to 10% (p = 0.04), respectively, from diagnosis to follow-up. Also, plasma cells and microenvironment cells HLA-DR expression augmented during SMM evolution from 7 to 10% (p = 0.04) and 29 to 39% (p = 0.01), respectively. When comparing group A vs group B, we found an increased CD68-KP1+ cell infiltration in favor of group B at diagnosis (23 vs 28%, p = 0.01) and a greater plasma cell infiltration at follow-up (50 vs 26%, p < 0.01). Our findings suggest how immune escape mechanisms appear earlier during multiple myeloma evolution, and that LAG3 could be a possible immunologic target in this setting.

Monoclonal gammopathy of undetermined significance

Monoclonal gammopathy of undetermined significance (MGUS) is a premalignant plasma cell dyscrasia that consistently precedes multiple myeloma (MM) with a 1% risk of progression per year. Recent advances have improved understanding of the complex genetic and immunologic factors that permit progression from the aberrant plasma cell clone to MGUS and overt MM. Additional evidence supports bidirectional interaction of MGUS cells with surrounding cells in the bone marrow niche that regulates malignant transformation. However, there are no robust prognostic biomarkers. Herein we review the current body of literature on the biology of MGUS and provide a rationale for the improved identification of high-risk MGUS patients who may be appropriate for novel clinical interventions to prevent progression or eradicate premalignant clones prior to the development of overt MM.

Immunogenic Cell Death and Immunotherapy of Multiple Myeloma

Over the past decades, immunotherapy has demonstrated a prominent clinical efficacy in a wide variety of human tumors. For many years, apoptosis has been considered a non-immunogenic or tolerogenic process whereas necrosis or necroptosis has long been acknowledged to play a key role in inflammation and immune-related processes. However, the new concept of “immunogenic cell death” (ICD) has challenged this traditional view and has granted apoptosis with immunogenic abilities. This paradigm shift offers clear implications in designing novel anti-cancer therapeutic approaches. To date, several screening studies have been carried out to discover bona fide ICD inducers and reveal the inherent capacity of a wide variety of drugs to induce cell death-associated exposure of danger signals and to bring about in vivo anti-cancer immune responses. Recent shreds of evidence place ER stress at the core of all the scenarios where ICD occur. Furthermore, ER stress and the unfolded protein response (UPR) have emerged as important targets in different human cancers. Notably, in multiple myeloma (MM), a lethal plasma cell disorder, the elevated production of immunoglobulins leaves these cells heavily reliant on the survival arm of the UPR. For that reason, drugs that disrupt ER homeostasis and engage ER stress-associated cell death, such as proteasome inhibitors, which are currently used for the treatment of MM, as well as novel ER stressors are intended to be promising therapeutic agents in MM. This not only holds true for their capacity to induce cell death, but also to their potential ability to activate the immunogenic arm of the ER stress response, with the ensuing exposure of danger signals. We provide here an overview of the up-to-date knowledge regarding the cell death mechanisms involved in situations of ER stress with a special focus on the connections with the drug-induced ER stress pathways that evoke ICD. We will also discuss how this could assist in optimizing and developing better immunotherapeutic approaches, especially in MM treatment.

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

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

Loc108167440 suppressed myeloma cell growth by P53-mediated apoptosis

Multiple myeloma (MM) results from biased proliferation of cancerous plasma cells (PC). Therapeutic strategies that target MM PC will provide immense value to the treatment of MM. For this, it is necessary to identify novel molecules that differ between MM PC and healthy PC. RNA sequencing was used to determine differences in gene expression profiles between LPS-induced plasmablasts (PB)/PC and the PB-like myeloma SP 2/0 cell line. Compared to LPS-induced PB/PC, SP 2/0 cells expressed significantly lower levels of Loc108167440 mRNA. Loc108167440 overexpression reduced the number of SP 2/0 cells by stimulating apoptotic cell death. In addition, Loc108167440 overexpression suppressed tumor progression in the SP 2/0 xenograft mouse model. Finally, we demonstrated that Loc108167440 overexpression up-regulated expression of p53 in SP 2/0 cells. These results suggest that Loc108167440 overexpression suppressed SP 2/0 cell growth by inducing p53-mediated apoptosis. Thus, Loc108167440 overexpression may be a potential therapy for treating MM.

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.

Aberrant PD-1 ligand expression contributes to the myocardial inflammatory injury caused by Coxsackievirus B infection

Coxsackievirus group B (CVB) is considered as one of the most common pathogens of human viral myocarditis. CVB-induced myocarditis is mainly characterized by the persistence of the virus infection and immune-mediated inflammatory injury. Costimulatory signals are crucial for the activation of adaptive immunity. Our data reveal that the CVB type 3 (CVB3) infection altered the expression profile of costimulatory molecules in host cells. CVB3 infection caused the decrease of PD-1 ligand expression, partially due to the cleavage of AU-rich element binding protein AUF1 by the viral protease 3C^pro, leading to the exacerbated inflammatory injury of the myocardium. Moreover, systemic PD-L1 treatment, which augmented the apoptosis of proliferating lymphocytes, alleviated myocardial inflammatory injury. Our findings suggest that PD1-pathway can be a potential immunologic therapeutic target for CVB-induced myocarditis.

Immunotherapeutic Approaches for Multiple Myeloma: Where Are We Now?

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

Immunotherapy in myeloma: how far have we come?

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

B7-H3 promotes multiple myeloma cell survival and proliferation by ROS-dependent activation of Src/STAT3 and c-Cbl-mediated degradation of SOCS3

B7-H3 (CD276) is broadly overexpressed by multiple human cancers. It plays a vital role in tumor progression and has been accepted as one of the inhibitory B7 family checkpoint molecules. To identify the functions and underlying mechanisms of B7-H3 in multiple myeloma, we analyzed B7-H3 expression in myeloma patients and used siRNAs and overexpression plasmid of B7-H3 to investigate its roles and downstream signaling molecules in myeloma cell lines. The results showed that surface expression of B7-H3 was upregulated in myeloma samples and cell lines. Lower expression of B7-H3 in myeloma cells was associated with better progression-free survival. Myeloma cell survival, drug resistance, and tumor growth could be promoted by B7-H3. The molecular basis for these functional roles of B7-H3 involved the activation of JAK2/STAT3 via redox-mediated oxidation and activation of Src. We further identified a STAT3-promoting signaling pathway by which oxidant-mediated Src phosphorylation led to secondary activation of the E3 ubiquitin ligase c-Cbl. Activated c-Cbl subsequently caused specific proteasomal degradation of SOCS3, a negative regulator of JAK2/STAT3. These data indicate B7-H3's important role in the activation of ROS/Src/c-Cbl pathway in multiple myeloma which integrates redox regulation and sustained STAT3 activation at the level of degradation of STAT3 suppressor.