The T Cell in Myeloma

Pathogenesis and management of immune dysfunction secondary to B cell haematological malignancies

Malignancies of the B-lymphocyte lineage are among the most diagnosed haematological malignancies in clinical practice. In our community, multiple myeloma (MM) and its precursor condition monoclonal gammopathy of undetermined significance are the commonest, accounting for ~12% of diagnoses, followed by chronic lymphocytic leukaemia (CLL) and its precursor condition monoclonal B lymphocytosis, ~9%. Along with diffuse large B cell lymphoma, follicular lymphoma and marginal zone lymphoma, these conditions comprise around a third of all haematological malignancies diagnosed. Infection remains an important cause of mortality and morbidity in the management of patients with these conditions. This is in part treatment-related but also reflective of disease-related immune dysfunction. Infectious complications account for up to 50% of early mortality in patients with myeloma and up to 50% of all mortality in patients with CLL. A variety of strategies are available to decrease the morbidity and mortality of infectious complications; however, practices vary between countries and often between treating physicians. Treatment options have evolved significantly over the last decade, with the introduction of monoclonal antibodies, small molecule inhibitors, second- and third-generation immunomodulatory agents and CAR-T cell therapy. Much of the data that inform clinical practice in infection management predates current therapeutic approaches. This is in part because of the rapid development of new therapies but also reflective of the long natural history of many of these diseases and the need for prolonged periods of observation. In this article, we review the aspects of disease and treatment that contribute to immune dysfunction in MM, CLL and B-cell non-Hodgkin lymphoma and review the current strategies used to manage immune dysfunction and infection.

Comprehensive Single-Cell Immune Profiling Defines the Patient Multiple Myeloma Microenvironment Following Oncolytic Virus Therapy in a Phase Ib Trial

PURPOSE

Our preclinical studies showed that the oncolytic reovirus formulation pelareorep (PELA) has significant immunomodulatory anti-myeloma activity. We conducted an investigator-initiated clinical trial to evaluate PELA in combination with dexamethasone (Dex) and bortezomib (BZ) and define the tumor immune microenvironment (TiME) in patients with multiple myeloma treated with this regimen.

PATIENTS AND METHODS

Patients with relapsed/refractory multiple myeloma (n = 14) were enrolled in a phase Ib clinical trial (ClinicalTrials.gov: NCT02514382) of three escalating PELA doses administered on Days 1, 2, 8, 9, 15, and 16. Patients received 40 mg Dex and 1.5 mg/m2 BZ on Days 1, 8, and 15. Cycles were repeated every 28 days. Pre- and posttreatment bone marrow specimens (IHC, n = 9; imaging mass cytometry, n = 6) and peripheral blood samples were collected for analysis (flow cytometry, n = 5; T-cell receptor clonality, n = 7; cytokine assay, n = 7).

RESULTS

PELA/BZ/Dex was well-tolerated in all patients. Treatment-emergent toxicities were transient, and no dose-limiting toxicities occurred. Six (55%) of 11 response-evaluable patients showed decreased paraprotein. Treatment increased T and natural killer cell activation, inflammatory cytokine release, and programmed death-ligand 1 expression in bone marrow. Compared with nonresponders, responders had higher reovirus protein levels, increased cytotoxic T-cell infiltration posttreatment, cytotoxic T cells in significantly closer proximity to multiple myeloma cells, and larger populations of a novel immune-primed multiple myeloma phenotype (CD138+ IDO1+HLA-ABCHigh), indicating immunomodulation.

CONCLUSIONS

PELA/BZ/Dex is well-tolerated and associated with anti-multiple myeloma activity in a subset of responding patients, characterized by immune reprogramming and TiME changes, warranting further investigation of PELA as an immunomodulator.

Single-cell technologies in multiple myeloma: new insights into disease pathogenesis and translational implications

Multiple myeloma (MM) is a hematological malignancy characterized by clonal proliferation of plasma cells. Although therapeutic advances have been made to improve clinical outcomes and to prolong patients' survival in the past two decades, MM remains largely incurable. Single-cell sequencing (SCS) is a powerful method to dissect the cellular and molecular landscape at single-cell resolution, instead of providing averaged results. The application of single-cell technologies promises to address outstanding questions in myeloma biology and has revolutionized our understanding of the inter- and intra-tumor heterogeneity, tumor microenvironment, and mechanisms of therapeutic resistance in MM. In this review, we summarize the recently developed SCS methodologies and latest MM research progress achieved by single-cell profiling, including information regarding the cancer and immune cell landscapes, tumor heterogeneities, underlying mechanisms and biomarkers associated with therapeutic response and resistance. We also discuss future directions of applying transformative SCS approaches with contribution to clinical translation.

Machine learning-based infection prediction model for newly diagnosed multiple myeloma patients

Objective

To understand the infection characteristics and risk factors for infection by analyzing multicenter clinical data of newly diagnosed multiple myeloma (NDMM) patients.

Methods

This study reviewed 564 NDMM patients from 2 large tertiary hospitals from January 2018 to December 2021, of whom 395 comprised the training set and 169 comprised the validation set. Thirty-eight variables from first admission records were collected, including patient demographic characteristics, clinical scores and characteristics, laboratory indicators, complications, and medication history, and key variables were screened using the Lasso method. Multiple machine learning algorithms were compared, and the best performing algorithm was used to build a machine learning prediction model. The model performance was evaluated using the AUC, accuracy, and Youden's index. Finally, the SHAP package was used to assess two cases and demonstrate the application of the model.

Results

In this study, 15 important key variables were selected, namely, age, ECOG, osteolytic disruption, VCD, neutrophils, lymphocytes, monocytes, hemoglobin, platelets, albumin, creatinine, lactate dehydrogenase, affected globulin, β2 microglobulin, and preventive medicine. The predictive performance of the XGBoost model was significantly better than that of the other models (AUROC: 0.8664), and it also performed well for the expected dataset (accuracy: 68.64%).

Conclusion

A machine learning algorithm was used to establish an infection prediction model for NDMM patients that was simple, convenient, validated, and performed well in reducing the incidence of infection and improving the prognosis of patients.

Characterization of post-vaccination SARS-CoV-2 T cell subtypes in patients with different hematologic malignancies and treatments

Background

To evaluate the benefits of SARS-CoV-2 vaccination in cancer patients it is relevant to understand the adaptive immune response elicited after vaccination. Patients affected by hematologic malignancies are frequently immune-compromised and show a decreased seroconversion rate compared to other cancer patients or controls. Therefore, vaccine-induced cellular immune responses in these patients might have an important protective role and need a detailed evaluation.

Methods

Certain T cell subtypes (CD4, CD8, Tfh, γδT), including cell functionality as indicated by cytokine secretion (IFN, TNF) and expression of activation markers (CD69, CD154) were assessed via multi-parameter flow cytometry in hematologic malignancy patients (N=12) and healthy controls (N=12) after a second SARS-CoV-2 vaccine dose. The PBMC of post-vaccination samples were stimulated with a spike-peptide pool (S-Peptides) of SARS-CoV-2, with CD3/CD28, with a pool of peptides from the cytomegalovirus, Epstein-Barr virus and influenza A virus (CEF-Peptides) or left unstimulated. Furthermore, the concentration of spike-specific antibodies has been analyzed in patients.

Results

Our results indicate that hematologic malignancy patients developed a robust cellular immune response to SARS-CoV-2 vaccination comparable to that of healthy controls, and for certain T cell subtypes even higher. The most reactive T cells to SARS-CoV-2 spike peptides belonged to the CD4 and Tfh cell compartment, being median (IQR), 3.39 (1.41-5.92) and 2.12 (0.55-4.14) as a percentage of IFN- and TNF-producing Tfh cells in patients. In this regard, the immunomodulatory treatment of patients before the vaccination period seems important as it was strongly associated with a higher percentage of activated CD4 and Tfh cells. SARS-CoV-2- and CEF-specific T cell responses significantly correlated with each other. Compared to lymphoma patients, myeloma patients had an increased percentage of SARS-CoV-2-specific Tfh cells. T-SNE analysis revealed higher frequencies of γδT cells in patients compared to controls, especially in myeloma patients. In general, after vaccination, SARS-CoV-2-specific T cells were also detectable in patients without seroconversion.

Conclusion

Hematologic malignancy patients are capable of developing a SARS-CoV-2-specific CD4 and Tfh cellular immune response after vaccination, and certain immunomodulatory therapies in the period before vaccination might increase the antigen-specific immune response. A proper response to recall antigens (e.g., CEF-Peptides) reflects immune cellular functionality and might be predictive for generating a newly induced antigen-specific immune response as is expected after SARS-CoV-2 vaccination.

Tumor and microenvironmental mechanisms of resistance to immunomodulatory drugs in multiple myeloma

Resistance to immunomodulatory drugs (IMiDs®) is a major cause of treatment failure, disease relapse and ultimately poorer outcomes in multiple myeloma (MM). In order to optimally deploy IMiDs and their newer derivates CRBN E3 ligase modulators (CELMoDs®) into future myeloma therapeutic regimens, it is imperative to understand the mechanisms behind the inevitable emergence of IMiD resistance. IMiDs bind and modulate Cereblon (CRBN), the substrate receptor of the CUL4CRBN E3 ubiquitin ligase, to target novel substrate proteins for ubiquitination and degradation. Most important of these are IKZF1 and IKZF3, key MM survival transcription factors which sustain the expression of myeloma oncogenes IRF4 and MYC. IMiDs directly target MM cell proliferation, but also stimulate T/NK cell activation by their CRBN-mediated effects, and therefore enhance anti-MM immunity. Thus, their benefits in myeloma are directed against tumor and immune microenvironment - and in considering the mechanisms by which IMiD resistance emerges, both these effects must be appraised. CRBN-dependent mechanisms of IMiD resistance, including CRBN genetic aberrations, CRBN protein loss and CRBN-substrate binding defects, are beginning to be understood. However, only a proportion of IMiD-resistant cases are related to CRBN and therefore additional mechanisms, which are currently less well described, need to be sought. These include resistance within the immune microenvironment. Here we review the existing evidence on both tumor and immune microenvironment mechanisms of resistance to IMiDs, pose important questions for future study, and consider how knowledge regarding resistance mechanism may be utilized to guide treatment decision making in the clinic.

CAR‐T cells derived from multiple myeloma patients at diagnosis have improved cytotoxic functions compared to those produced at relapse or following daratumumab treatment

Chimeric antigen receptor T cells (CAR‐T) have provided promising results in multiple myeloma (MM). However, many patients still relapse, pointing toward the need of improving this therapy. Here, we analyzed peripheral blood T cells from MM patients at different stages of the disease and investigated their phenotype and capacity to generate functional CAR‐T directed against CS1 or B Cell Maturation antigen. We found a decrease in naive T cells and elevated frequencies of exhaustion markers in T cells from treated MM patients. Interestingly, individuals treated with daratumumab display elevated ratios of central memory T cells. CAR‐T derived from patients at relapse show reduced in vitro expansion and cytotoxic capacities in response to MM cells compared to those produced at diagnosis. Of note, CAR‐T from daratumumab treated patients display intermediate defects. Reduced anti‐myeloma activity of CAR T cells from treated patients was also observed in a mouse model. Our findings suggest that T cell defects in MM patients, specifically during relapse, have a major impact on their capacity to generate efficient therapeutic CAR‐T. Selecting naive or central memory T cell subsets to generate therapeutic T cells could improve the CAR‐T therapy for MM.

The Evolution Of Immune Dysfunction In Multiple Myeloma

OBJECTIVES

This review discusses the role of immune dysfunction at the different stages of MM.

METHODS

Narrative review RESULTS: Multiple myeloma (MM) is a complex disease and immune dysfunction has been known to play an important role in disease pathogenesis, progression, and drug resistance. MM is known to be preceded by asymptomatic precursor states and progression from the precursor states to MM is likely related to a progressive impairment of the immune system.

CONCLUSIONS

An understanding of the role of the immune system in the progression of MM is important to guide the development of immunotherapeutic strategies for this disease.

Case Report: Invasive Fungal Infection and Daratumumab: A Case Series and Review of Literature

Life expectancy of multiple myeloma (MM) patients has improved in last years due to the advent of anti-CD38 monoclonal antibodies in combination with immunomodulators and proteasome inhibitors. However, morbidity and mortality related to infections remain high and represent a major concern. This paper describes the “real life” risk of invasive fungal infections (IFI) in patients treated with daratumumab-based therapy and reviews the relevant literature. In a series of 75 patients we only observed three cases of fungal pneumonia. Unfortunately, the early signs and symptoms were not specific for fungal infection. Diagnostic imaging, microbiology and patient history, especially previous therapies, are critical in the decision to start antifungal treatment. Recognising the subgroup of MM patients with high risk of IFI can increase the rate of diagnosis, adequate treatment and MM-treatment recovery.

The Role of T Cell Immunity in Monoclonal Gammopathy and Multiple Myeloma: From Immunopathogenesis to Novel Therapeutic Approaches

Multiple Myeloma (MM) is a malignant growth of clonal plasma cells, typically arising from asymptomatic precursor conditions, namely monoclonal gammopathy of undetermined significance (MGUS) and smoldering MM (SMM). Profound immunological dysfunctions and cytokine deregulation are known to characterize the evolution of the disease, allowing immune escape and proliferation of neoplastic plasma cells. In the past decades, several studies have shown that the immune system can recognize MGUS and MM clonal cells, suggesting that anti-myeloma T cell immunity could be harnessed for therapeutic purposes. In line with this notion, chimeric antigen receptor T cell (CAR-T) therapy is emerging as a novel treatment in MM, especially in the relapsed/refractory disease setting. In this review, we focus on the pivotal contribution of T cell impairment in the immunopathogenesis of plasma cell dyscrasias and, in particular, in the disease progression from MGUS to SMM and MM, highlighting the potentials of T cell-based immunotherapeutic approaches in these settings.

Gnawing Between Cells and Cells in the Immune System: Friend or Foe? A Review of Trogocytosis

Trogocytosis occurs when one cell contacts and quickly nibbles another cell and is characterized by contact between living cells and rapid transfer of membrane fragments with functional integrity. Many immune cells are involved in this process, such as T cells, B cells, NK cells, APCs. The transferred membrane molecules including MHC molecules, costimulatory molecules, receptors, antigens, etc. An increasing number of studies have shown that trogocytosis plays an important role in the immune system and the occurrence of relevant diseases. Thus, whether trogocytosis is a friend or foe of the immune system is puzzling, and the precise mechanism underlying it has not yet been fully elucidated. Here, we provide an integrated view of the acquired findings on the connections between trogocytosis and the immune system.

Inflammation and infection in plasma cell disorders: how pathogens shape the fate of patients

The role of infection and chronic inflammation in plasma cell disorders (PCD) has been well-described. Despite not being a diagnostic criterion, infection is a common complication of most PCD and represents a significant cause of morbidity and mortality in this population. As immune-based therapeutic agents are being increasingly used in multiple myeloma, it is important to recognize their impact on the epidemiology of infections and to identify preventive measures to improve outcomes. This review outlines the multiple factors attributed to the high infectious risk in PCD (e.g. the underlying disease status, patient age and comorbidities, and myeloma-directed treatment), with the aim of highlighting future prophylactic and preventive strategies that could be implemented in the clinic. Beyond this, infection and pathogens as an entity are believed to also influence disease biology from initiation to response to treatment and progression through a complex interplay involving pathogen exposure, chronic inflammation, and immune response. This review will outline both the direct and indirect role played by oncogenic pathogens in PCD, highlight the requirement for large-scale studies to decipher the precise implication of the microbiome and direct pathogens in the natural history of myeloma and its precursor disease states, and understand how, in turn, pathogens shape plasma cell biology.

Harnessing the Potential of NK Cell-Based Immunotherapies against Multiple Myeloma

Natural killer (NK) cell-based therapies have emerged as promising anticancer treatments due to their potency as cytolytic effectors and synergy with concurrent treatments. Multiple myeloma (MM) is an aggressive B-cell malignancy that, despite development of novel therapeutic agents, remains incurable with a high rate of relapse. In MM, the inhospitable tumor microenvironment prevents host NK cells from exerting their cytolytic function. The development of NK cell immunotherapy works to overcome this altered immune landscape and can be classified in two major groups based on the origin of the cell: autologous or allogeneic. In this review, we compare the treatments in each group, such as autologous chimeric antigen receptor (CAR) NKs and allogeneic off-the-shelf NK cell infusions, and their combinatorial effect with existing MM therapies including monoclonal antibodies and proteasome inhibitors. We also discuss their placement in clinical treatment regimens based on the immune profile of each patient. Through this examination, we would like to discover precisely when each NK cell-based treatment will produce the maximum benefit to the MM patient.

Lymphocytopenia and Anti-CD38 Directed Treatment Impact the Serological SARS-CoV-2 Response after Prime Boost Vaccination in Patients with Multiple Myeloma

Even though several SARS-CoV-2 vaccines have shown high effectiveness in the prevention of COVID-19 in healthy subjects, vaccination response in patients with plasma-cell-related disorders (PCD) remains widely unknown. Here, we report on an analysis describing the serological response after prime-boost SARS-CoV-2 vaccination in PCD patients, as compared to a healthy control group, and on possible influencing factors of serological responses. Blood samples were analyzed for the presence of quantitative anti-SARS-CoV-2 spike RBD Ig. A total of 82 patients were included; 67 received mRNA-, eight vector-based and four heterologous vaccinations. SARS-CoV-2 antibody titers (SP-AbT) were assessed in a mean of 23 days (SD ± 11 days) after the first and in a mean 21 days (SD ± 9) after prime-boost vaccination. A positive SP-AbT was detected in 31.9% of PCD patients after the first vaccination, and in 88.9% (44/49) after prime-boost vaccination, which was significantly less likely than that in the control group (100%, 78/78) (p = 0.008). Furthermore, we have been able to validate our previously suggested threshold of 30 CD19+ B lymphocytes/µL as being predictive for SP-AbT development. Despite anti-CD38 directed therapy, quadruplet treatment, higher age and missing deep remission, which correlated negatively with SP-AbT appearance, SP-AbT formation is possible in a majority of myeloma patients after prime-boost vaccination.

Post-Vaccination Anti-SARS-CoV-2-Antibody Response in Patients with Multiple Myeloma Correlates with Low CD19+ B-Lymphocyte Count and Anti-CD38 Treatment

Simple Summary

The global impact of the current COVID-19 pandemic has led to the impressively rapid development of multiple anti-SARS-CoV-2 vaccines. However, only few data are available regarding the efficacy of anti-SARS-CoV-2 vaccines in patients with hematological malignancies, and, in particular, plasma cell neoplasia. This ongoing observational study aimed to describe the level of post-vaccination anti-SARS-CoV-2-antibodies depending on multiple clinical factors including B lymphocyte count and current therapy of 82 patients with multiple myeloma and related plasma cell neoplasia, after the first dose of anti-SARS-CoV-2 vaccination. A positive SARS-CoV-2 spike protein antibody titer (SP-AbT) was detected in 23% of assessable patients. SARS-CoV-2 SP-AbT was significantly higher in patients with higher CD19+ B lymphocyte counts and current treatment with anti-CD38-antibodies has led to significantly reduced SP-AbT titers. Based on our results, the majority of myeloma patients respond poorly after receiving the first dose of any anti-SARS-CoV-2 vaccination and need booster vaccination.

Abstract

Few data are available regarding the efficacy of anti-SARS-CoV-2 vaccines in patients with hematological malignancies, and particular, plasma cell neoplasia. This ongoing single-center study aimed to describe the level of post-vaccination anti-SARS-CoV-2-antibodies depending on B lymphocyte count, current therapy, and remission status of patients with multiple myeloma and related plasma cell dyscrasia, after the first dose of anti-SARS-CoV-2 vaccination. The 82 patients included in this study received SARS-CoV-2 vaccines (including mRNA- and vector-based vaccines) as a routine measure. After the first vaccination, a positive SARS-CoV-2 spike protein antibody titer (SP-AbT) was detected in 23% of assessable patients. SARS-CoV-2 SP-AbT was significantly higher in patients with higher CD19+ B lymphocyte counts. A cut-off value of ≥30 CD19+ B cells/µL was significantly positive correlating with higher SARS-CoV-2 SP-AbT. In contrast, current treatment with anti-CD38-antibodies has led to significantly reduced SP-AbT titers. Furthermore, in multivariable linear regression, higher age and insufficiently controlled disease significantly correlated negatively with SARS-CoV-2 SP-AbT. Conversely, treatment with immunomodulatory drugs did not harm the development of antibody titers. Based on our results, the majority of myeloma patients respond poorly after receiving the first dose of any anti-SARS-CoV-2 vaccination and need booster vaccination.

Genotype-immunophenotype analysis reveals the immunogenomic subtype and prognosis of multiple myeloma

Immune dysfunction plays an important role in tumour development, recurrence, therapeutic responses and overall survival (OS). Multiple myeloma (MM) is a clonal B-cell malignancy which characterized by anti-tumoural immune dysfunction. In this study, we analysed 28 tumour-immune-related pathways and calculated the immune pathway score through published microarray data from the Gene Expression Omnibus (GEO) data portal. A training set of 345 patients and a validation set of 214 patients with primary MM were chosen. We performed least absolute shrinkage and selection operator (LASSO) analysis to identify prognostic factors. Then, we used cluster analysis to divide patients into three immunogenomic subtypes, which named abnormal immune activated type, common type and anti-myeloma immune activated type. Log‑rank tests showed that anti-myeloma immune activated type had the best prognosis and abnormal immune activated type had the shortest OS (P = 0.000) and event-free survival (EFS) (P = 0.000). Multivariate Cox also indicated that the immunogenomic subtype was an independent predictor of OS (P = 0.001) and EFS (P = 0.000). We also analysed the characteristics and the immune-response patterns of different subtypes. Then, we established a mathematical model to classify patients in the validation set. In the validation set, patients with different immunogenomic subtypes also had a significantly different OS (P = 0.001) and EFS (P = 0.005). Our study explored tumour-immune-related pathways at a multi-dimensional level and found the immunogenomic subtype of MM. Potential mechanisms on the genetic level of how tumour-immunity influences the prognosis and therapeutic responses are provided. The immunogenomic subtype may be feasible for deciding clinical treatment in the future.

Inverse relationship between oligoclonal expanded CD69- TTE and CD69+ TTE cells in bone marrow of multiple myeloma patients

CD8+CD57+ terminal effector T (TTE) cells are a component of marrow-infiltrating lymphocytes and may contribute to the altered immune responses in multiple myeloma (MM) patients. We analyzed TTE cells in the bone marrow (BM) and peripheral blood (PB) of age-matched controls and patients with monoclonal gammopathy of undetermined significance (MGUS), smoldering MM (SMM), and newly diagnosed (ND) MM using flow cytometry, mass cytometry, and FlowSOM clustering. TTE cells are heterogeneous in all subjects, with BM containing both CD69- and CD69+ subsets, while only CD69- cells are found in PB. Within the BM-TTE compartment, CD69- and CD69+ cells are found in comparable proportions in controls, while CD69- cells are dominant in MGUS and SMM and predominantly either CD69- or CD69+ cells in NDMM. A positive relationship between CD69+TTE and CD69-TTE cells is observed in the BM of controls, lost in MGUS, and converted to an inverse relationship in NDMM. CD69-TTE cells include multiple oligoclonal expansions of T-cell receptor/Vβ families shared between BM and PB of NDMM. Oligoclonal expanded CD69-TTE cells from the PB include myeloma-reactive cells capable of killing autologous CD38hi plasma cells in vitro, involving degranulation and high expression of perforin and granzyme. In contrast to CD69-TTE cells, oligoclonal expansions are not evident within CD69+TTE cells, which possess low perforin and granzyme expression and high inhibitory checkpoint expression and resemble T resident memory cells. Both CD69-TTE and CD69+TTE cells from the BM of NDMM produce large amounts of the inflammatory cytokines interferon-γ and tumor necrosis factor α. The balance between CD69- and CD69+ cells within the BM-TTE compartment may regulate immune responses in NDMM and contribute to the clinical heterogeneity of the disease.

Understanding the Role of T-Cells in the Antimyeloma Effect of Immunomodulatory Drugs

Immunomodulatory drugs (IMiDs) are effective treatments for patients with multiple myeloma. IMiDs have pleotropic effects including targeting the myeloma cells directly, and improving the anti-myeloma immune response. In the absence of myeloma cells, lenalidomide and pomalidomide induce CD4⁺ T cell secretion of IL-2 and indirect activation of Natural Killer (NK) cells. In the context of T cell receptor ligation, IMiDs enhance T cell proliferation, cytokine release and Th1 responses, both in vivo and in vitro. Furthermore, combination treatment of IMiDs and myeloma-targeting monoclonal antibodies eg. daratumumab (anti-CD38) and elotuzumab (anti-SLAMF7), checkpoint inhibitors, or bispecific T cell engagers showed synergistic effects, mainly via enhanced T and NK cell dependent cellular toxicity and T cell proliferation. Conversely, the corticosteroid dexamethasone can impair the immune modulatory effects of IMiDs, indicating that careful choice of myeloma drugs in combination with IMiDs is key for the best anti-myeloma therapeutic efficacy. This review presents an overview of the role for T cells in the overall anti-myeloma effects of immunomodulatory drugs.

Isatuximab as monotherapy and combined with dexamethasone in patients with relapsed/refractory multiple myeloma

This phase 2 study evaluated isatuximab as monotherapy or combined with dexamethasone in relapsed/refractory multiple myeloma (RRMM). Patients had RRMM refractory to an immunomodulatory drug (IMiD) and a proteasome inhibitor (PI) or had received ≥3 prior lines of therapy incorporating an IMiD and PI. Patients received isatuximab either as monotherapy (20 mg/kg on days 1, 8, 15, and 22 [once weekly] of cycle 1 followed by 20 mg/kg on days 1 and 15 of subsequent cycles; Isa group) or in combination with dexamethasone (40 mg/d [20 mg/d in patients aged ≥75 years] once weekly; Isa-dex group). Treated patients (N = 164) had received a median of 4 (range, 2-10) prior treatment lines. Patients received a median of 5 (1-24) and 7 (1-22) treatment cycles; at data cutoff, 13 (11.9%) of 109 and 15 (27.3%) of 55 patients remained on treatment in the Isa and Isa-dex arms, respectively. Overall response rate (primary efficacy end point) was 23.9% in the Isa arm and 43.6% in the Isa-dex arm (odds ratio, 0.405; 95% confidence interval, 0.192-0.859; P = .008). Median progression-free survival and overall survival were 4.9 and 18.9 months for Isa, and 10.2 and 17.3 months for Isa-dex. Infusion reactions (mostly grade 1/2) and hematologic abnormalities were the most common adverse events. There was a similar incidence of grade 3 or higher infections in both groups (22.0% and 21.8%). In conclusion, addition of dexamethasone to isatuximab increased response rates and survival outcomes with no detrimental effect on safety. This trial was registered at www.clinicaltrials.gov as #NCT01084252.

Treg and Oligoclonal Expansion of Terminal Effector CD8+ T Cell as Key Players in Multiple Myeloma

The classical paradigm of host-tumor interaction, i.e. elimination, equilibrium, and escape (EEE), is reflected in the clinical behavior of myeloma which progresses from the premalignant condition, Monoclonal Gammopathy of Unknown Significance (MGUS). Despite the role of other immune cells, CD4⁺ regulatory T cells (Treg) and cytotoxic CD8⁺ T cells have emerged as the dominant effectors of host control of the myeloma clone. Progression from MGUS to myeloma is associated with alterations in Tregs and terminal effector CD8⁺ T cells (T_TE). These changes involve CD39 and CD69 expression, affecting the adenosine pathway and residency in the bone marrow (BM) microenvironment, together with oligoclonal expansion within CD8⁺ T_TE cells. In this mini-review article, in the context of earlier data, we summarize our recent understanding of Treg involvement in the adenosine pathway, the significance of oligoclonal expansion within CD8⁺ T_TE cells and BM-residency of CD8⁺ T_TE cells in MGUS and newly diagnosed multiple myeloma patients.

Hematopoietic versus Solid Cancers and T Cell Dysfunction: Looking for Similarities and Distinctions

Simple Summary

Dysfunction of the immune T cell compartment occurs in many hematopoietic as well as solid cancers and hampers successful application of new immunotherapeutic approaches. A complete understanding of T cell dysfunction might improve the outcome of such therapies, but an overview in the various cancers is still lacking. We aim to map areas of similarities and differences in solid versus hematopoietic malignancies, providing a high-level rather than a detailed perspective on T cell dysfunction in those tumors.

Abstract

Cancer cells escape, suppress and exploit the host immune system to sustain themselves, and the tumor microenvironment (TME) actively dampens T cell function by various mechanisms. Over the last years, new immunotherapeutic approaches, such as adoptive chimeric antigen receptor (CAR) T cell therapy and immune checkpoint inhibitors, have been successfully applied for refractory malignancies that could only be treated in a palliative manner previously. Engaging the anti-tumor activity of the immune system, including CAR T cell therapy to target the CD19 B cell antigen, proved to be effective in acute lymphocytic leukemia. In low-grade hematopoietic B cell malignancies, such as chronic lymphocytic leukemia, clinical outcomes have been tempered by cancer-induced T cell dysfunction characterized in part by a state of metabolic lethargy. In multiple myeloma, novel antigens such as BCMA and CD38 are being explored for CAR T cells. In solid cancers, T cell-based immunotherapies have been applied successfully to melanoma and lung cancers, whereas application in e.g., breast cancer lags behind and is modestly effective as yet. The main hurdles for CAR T cell immunotherapy in solid tumors are the lack of suitable antigens, anatomical inaccessibility, and T cell anergy due to immunosuppressive TME. Given the wide range of success and failure of immunotherapies in various cancer types, it is crucial to comprehend the underlying similarities and distinctions in T cell dysfunction. Hence, this review aims at comparing selected, distinct B cell-derived versus solid cancer types and at describing means by which malignant cells and TME might dampen T cell anti-tumor activity, with special focus on immunometabolism. Drawing a meaningful parallel between the efficacy of immunotherapy and the extent of T cell dysfunction will shed light on areas where we can improve immune function to battle cancer.

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.

Peripheral Absolute Lymphocyte Count: An Economical and Clinical Available Immune-Related Prognostic Marker for Newly Diagnosed Multiple Myeloma

Background

To find economical and clinically available immune-related prognostic markers that could predict the overall survival (OS) of newly diagnosed multiple myeloma (NDMM) in the new drug era.

Material/Methods

Absolute lymphocyte count (ALC) and absolute monocyte count (AMC) were measured in routine blood samples from 102 patients with NDMM, and the lymphocyte-monocyte ratio (LMR) was derived. All the patients were receiving bortezomib-based chemotherapy as induction treatment. Log-rank testing was used for comparing the differences between groups. Univariate and multivariate tests were used to identify prognostic markers.

Results

The median ALC and LMR values at diagnosis were 1.43×10⁹/L and 3.7, respectively, and served as the cutoff point. As prognostic factors, ALC, LMR, and a new staging system combining ALC and the ISS staging system (L-ISS) were expected to have a significant impact on predicting OS. Furthermore, multivariate analysis showed that ALC ≥1.43×10⁹/L (hazard ratio [HR]: 0.223; 95% confidence interval [CI]: 0.071–0.705; P=0.011), LMR ≥3.7 (HR: 0.363; 95% CI: 0.139–0.947; P=0.038), and L-ISS late stage (HR: 1.619; 95% CI: 1.065–2.743; P=0.027) were independent predictors for OS.

Conclusions

ALC and LMR can serve as surrogate markers for patients’ antitumor immunity at the initial diagnosis of multiple myeloma. A new immune-related staging system, L-ISS, which combines ALC and the ISS staging system, can predict clinical outcomes in patients who are receiving bortezomib-based chemotherapy.

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.

Risk and impact of invasive fungal infections in patients with multiple myeloma

Infection is associated with great morbidity and mortality in patients with multiple myeloma (MM), but evidence for invasive fungal infections (IFIs) is lacking. We aimed to investigate risk factors for IFI in MM patients and to determine its impact on patients' survival. We retrospectively analyzed MM patients at Taipei Veterans General Hospital in Taiwan between January 2002 and October 2018. MM was diagnosed according to the International Myeloma Working Group criteria. IFI was defined according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria. All risk factors of IFI in MM patients were estimated using Cox regression models in the univariate and multivariate analyses. Of the 623 patients recruited, 22 (3.5%) were diagnosed with proven or probable IFI. Light chain disease (adjusted hazard ratio [HR] 6.74, 95% confidence interval [CI] 2.10-21.66), hemoglobin less than 8 g/dl (adjusted HR 3.34, 95% CI 1.32-8.42), serum albumin < 3.5 g/dl (adjusted HR 3.24, 95% CI 1.09-9.68), and having received allogeneic stem cell transplantation (allo-SCT) (adjusted HR 5.98, 95% CI 1.62-22.03) were significantly associated with IFI in the multivariate analysis. Contracting IFI was in turn associated with early mortality (adjusted HR 11.60, 95% CI 1.26-106.74). Light chain disease, anemia, hypoalbuminemia, and receiving allo-SCT were independent predictors of IFI in MM patients. The early mortality risk is much higher in those encountering IFI. Physicians must be aware of the rare but potentially lethal infections.

Low absolute CD4+ T cell counts in peripheral blood predict poor prognosis in patients with newly diagnosed multiple myeloma

The T lymphocyte system plays an active role in tumor immunosurveillance in multiple myeloma (MM), and abnormal T lymphocyte populations are often observed in patients with MM. In the current study, we evaluated the prognostic impact of abnormal T lymphocyte subset distributions in patients with newly diagnosed MM (NDMM). Between December 2012 to October 2016, 110 NDMM patients were included in this study. Multiparameter flow cytometry was applied to quantitatively analysis the peripheral blood T lymphocyte subsets, including CD4⁺ T cell, CD8⁺ T cell, and CD4/CD8 ratio. Survival analyses were performed based on the patients' clinical data and the quantity of T lymphocyte subsets. The median follow-up time was 27.0 months (range, 2.5-66). Baseline percentages and absolute CD4⁺ T cell counts and the CD4/CD8 ratio were positively correlated with both overall survival (OS) and progression-free survival (PFS) according to Kaplan-Meier curves (p < .05). In the multivariate COX analysis, lower CD4⁺ T cell count was an independent unfavorable factor in predicting both OS (p = .016) and PFS (p = .010). Furthermore, lower CD4/CD8 ratio was an independent adverse prognostic factor for shorter PFS (p = .017). These results suggested that T lymphocyte subsets were crucial indicators in correlation with MM patients' prognosis. Low CD4⁺ T cell counts and CD4/CD8 ratio were independent unfavorable prognostic predictors for patients with MM at diagnosis.

A Unique Role of T Helper 17 Cells in Different Treatment Stages of Multiple Myeloma

BACKGROUND

T helper 17 (Th17) cells are a subset of CD4-positive T cells, which secrete interleukin 17 and specifically express the retinoic acid receptor-related orphan receptors γt gene. Recently, Studies have shown that the level of Th17 cells in peripheral blood of newly diagnosed multiple myeloma (MM) patients is significantly higher than that of healthy persons. Th17 cells play an important role in the immune microenvironment of MM and interact with tumor cells, osteoclasts, and osteoblasts. Th17 cells might be a potential therapeutic target for MM patients.

PATIENTS AND METHODS

In this study, we further tracked the levels of Th17 cells in peripheral blood of 56 patients with MM from newly diagnosed to partial remission to complete remission to relapse and 11 healthy donors.

RESULTS

The level of Th17 cells increased further when the disease reached partial remission, decreased to normal level when it reached complete remission, and increased again when the disease recurred. In addition, we also found that in newly diagnosed MM patients, Th17 cell levels fluctuated greatly; not all patients were upregulated, and patients with normal Th17 cell levels had the highest chance of complete remission.

CONCLUSION

Th17 cells contribute to the stratification of different treatment stages of MM patients. The level of Th17 cells in patients with newly diagnosed MM is associated with the treatment outcome of complete remission.

Bone Marrow Stromal Cells-Induced Drug Resistance in Multiple Myeloma

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

T Cell Transcriptional Profiling and Immunophenotyping Uncover LAG3 as a Potential Significant Target of Immune Modulation in Multiple Myeloma

Autologous stem cell transplant (ASCT) is the standard of care for patients with multiple myeloma (MM). The clinical significance of peripheral blood T lymphocyte (PBTL) immunologic changes associated with ASCT is poorly understood. Here we evaluated T cell transcriptional messenger RNA profiles and immunophenotypes to correlate immunologic senescence, exhaustion, and anergy with clinical endpoints in a cohort of patients with MM undergoing ASCT. ASCT induced global transcriptional T cell changes and altered molecular levels of markers of T cell subtypes, T cell activation, and exhaustion. These included reduced CD4/CD8 ratio, skewing toward the Th1 subset, reduced expression of costimulatory receptors CD27 and CD28, heightened T cell activation, and increased expression of immune modulatory molecules LAG3 and PD1. Multicolor flow cytometry experiments confirmed altered circulating CD4 and CD8 subsets and skewing toward differentiated effector cells. Moreover, ASCT promoted an exhausted immunophenotype in CD3⁺CD4⁺ subsets and a senescent immunophenotype in CD3⁺CD8⁺ subsets. Subset-specific altered expression was also seen for surface molecules with immunomodulatory function. ASCT affected soluble levels of molecules with immunomodulatory function by increasing plasma HVEM and TIM3. High molecular LAG3 level was associated with inferior event-free survival post-ASCT (hazard ratio = 5.44; confidence interval, 1.92 to 15.46; P = .001; adjusted P [controlling for false discovery rate] = .038). Using a comprehensive evaluation of PBTLs on a molecular and phenotypic level, we have identified that ASCT induces global T cell alterations with CD4 and CD8 subset-specific changes. Moreover, LAG3 emerged as an early biomarker of adverse events post-ASCT. These findings will support the development of treatment strategies targeting immune defects in MM to augment or restore T cell responses.

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.

Safety and efficacy of targeting CD138 with a chimeric antigen receptor for the treatment of multiple myeloma

After unprecedented successes in B-cell malignancies, chimeric antigen receptor T cells have recently been investigated for the treatment of multiple myeloma. Chimeric antigen receptor targeting T cells B-cell maturation antigen (BCMA) on malignant plasma cells have led to impressive clinical responses in recent trials. However, BCMA-negative relapses have been observed, supporting the need for complementary treatment strategies. Here, we explored the feasibility of targeting CD138 (syndecan-1), a surface marker expressed on both normal and malignant plasma cells. We showed that T cells from both healthy donors and from multiple myeloma patients, when transduced with a CD138-specific chimeric antigen receptor, can eliminate tumor cell lines and primary myeloma cells both in vitro and in vivo. CD138 is also expressed by putative myeloma stem cells identified by Hoechst staining, and these cells can be eliminated by CD138-specific chimeric antigen receptor T cells. Preclinical analyses did not identify any on target off tumor cytotoxicity against normal epithelial or endothelial cells, further supporting the rationale for the use of adoptively transferred CD138-specific chimeric antigen receptor T cells for the treatment of patients with relapsed/refractory multiple myeloma.

Evaluating the role of Tregs in the progression of multiple myeloma

The role of regulatory T-cells (Treg) and Th17 cells in the progression of multiple myeloma has been unclear. There are conflicting reports of the Treg and Th17 frequency being increased, decreased, and unchanged as compared with controls. In this study, we sought to characterize the T-cell subsets including Treg function in both blood and marrow compartments of monoclonal gammopathy of undetermined significance (MGUS) and multiple myeloma (MM). The Treg/Th17 ratio is skewed toward the suppressive phenotype in MGUS and MM. There are more activated and memory Tregs in the myeloma marrow. Although the myeloma Tregs are functional, they are less suppressive than Tregs in chronic lymphocytic leukemia where they drive disease progression. None of the T-cell subsets were found to have a clinical correlation with time to progression in MGUS or progression-free survival in myeloma. Tregs are important but unlikely major players in the progression of MGUS to MM.

Allogeneic CAR-T Cells: More than Ease of Access?

Patient derived anti-CD19 chimeric antigen receptor-T (CAR-T) cells are a powerful tool in achieving a complete remission in a range of B-cell malignancies, most notably B-acute lymphoblastic leukaemia (B-ALL) and diffuse large B-cell lymphoma (DLBCL). However, there are limitations, including inability to manufacture CAR-T cells from the patient's own T cells, disease progression and death prior to return of engineered cells. T cell dysfunction is known to occur in cancer patients, and several groups have recently described differences in CAR-T cells generated from chronic lymphocytic leukaemia (CLL) patients compared with those from a healthy donor. This is thought to contribute to the low response rate in this disease group. Healthy donor, gene-edited CAR-T cells which do not require human leucocyte antigen (HLA) matching have the potential to provide an 'off the shelf' product, overcoming the manufacturing difficulties of producing CAR-T cells for each individual patient. They may also provide a more functional, potent product for malignancies such as CLL, where T cell dysfunction is common and frequently cannot be fully reversed during the manufacturing process. Here we review the potential benefits and obstacles for healthy donor, allogeneic CAR-T cells.

Targeting B Cell Maturation Antigen (BCMA) in Multiple Myeloma: Potential Uses of BCMA-Based Immunotherapy

The approval of the first two monoclonal antibodies targeting CD38 (daratumumab) and SLAMF7 (elotuzumab) in late 2015 for treating relapsed and refractory multiple myeloma (RRMM) was a critical advance for immunotherapies for multiple myeloma (MM). Importantly, the outcome of patients continues to improve with the incorporation of this new class of agents with current MM therapies. However, both antigens are also expressed on other normal tissues including hematopoietic lineages and immune effector cells, which may limit their long-term clinical use. B cell maturation antigen (BCMA), a transmembrane glycoprotein in the tumor necrosis factor receptor superfamily 17 (TNFRSF17), is expressed at significantly higher levels in all patient MM cells but not on other normal tissues except normal plasma cells. Importantly, it is an antigen targeted by chimeric antigen receptor (CAR) T-cells, which have already shown significant clinical activities in patients with RRMM who have undergone at least three prior treatments, including a proteasome inhibitor and an immunomodulatory agent. Moreover, the first anti-BCMA antibody–drug conjugate also has achieved significant clinical responses in patients who failed at least three prior lines of therapy, including an anti-CD38 antibody, a proteasome inhibitor, and an immunomodulatory agent. Both BCMA targeting immunotherapies were granted breakthrough status for patients with RRMM by FDA in Nov 2017. Other promising BCMA-based immunotherapeutic macromolecules including bispecific T-cell engagers, bispecific molecules, bispecific or trispecific antibodies, as well as improved forms of next generation CAR T cells, also demonstrate high anti-MM activity in preclinical and even early clinical studies. Here, we focus on the biology of this promising MM target antigen and then highlight preclinical and clinical data of current BCMA-targeted immunotherapies with various mechanisms of action. These crucial studies will enhance selective anti-MM response, transform the treatment paradigm, and extend disease-free survival in MM.

Vγ9Vδ2 T Cells in the Bone Marrow of Myeloma Patients: A Paradigm of Microenvironment-Induced Immune Suppression

Vγ9Vδ2 T cells are non-conventional T cells with a natural inclination to recognize and kill cancer cells. Malignant B cells, including myeloma cells, are privileged targets of Vγ9Vδ2 T cells in vitro. However, this inclination is often lost in vivo due to multiple mechanisms mediated by tumor cells and local microenvironment. Multiple myeloma (MM) is a paradigm disease in which antitumor immunity is selectively impaired at the tumor site. By interrogating the immune reactivity of bone marrow (BM) Vγ9Vδ2 T cells to phosphoantigens, we have revealed a very early and long-lasting impairment of Vγ9Vδ2 T-cell immune functions which is already detectable in monoclonal gammopathy of undetermined significance (MGUS) and not fully reverted even in clinical remission after autologous stem cell transplantation. Multiple cell subsets [MM cells, myeloid-derived suppressor cells, regulatory T cells, and BM-derived stromal cells (BMSC)] are involved in Vγ9Vδ2 T-cell inhibition via several immune suppressive mechanisms including the redundant expression of multiple immune checkpoints (ICPs). This review will address some aspects related to the dynamics of ICP expression in the BM of MM patients in relationship to the disease status (MGUS, diagnosis, remission, and relapse) and how this multifaceted ICP expression impairs Vγ9Vδ2 T-cell function. We will also provide some suggestions how to rescue Vγ9Vδ2 T cells from the immune suppression operated by ICP and to recover their antimyeloma immune effector functions at the tumor site.

Multiple Myeloma Index for Risk of Infection

Based on our earlier research into the main characteristics and risk factors for infections in hospitalized patients with multiple myeloma, we created the numerical Multiple Myeloma Index for Risk of Infection (MMIRI) to predict infection in myeloma patients. The included factors that could influence the pathogenesis and incidence of infections were sex, performance status, Durie Salmon stage of disease, International Staging System, serum creatinine level, immune paresis, neutropenia, serum ferritin level, the presence of any catheters, disease duration, stable/progressive disease, and type of therapy. For each of these parameters, the strength of association with infection was statistically estimated and specific number of points was assigned to each of these parameters, proportional to the strength of the association. When designing the MMIRI, we included only those parameters that we determined were pathophysiologically associated with the infection. After further statistical analysis, we identified an optimal cutoff score of 6 or above as indicating a significant risk for infection, with a sensitivity of 93.2% and specificity of 80.2%. The scoring system in the retrospective receiver operating characteristic analysis showed an area under the curve of 0.918. The potential value of the MMIRI is the possibility of identifying those patients who would benefit from the prophylactic administration of antibiotics and other anti-infective measures while minimizing the contribution to antibiotic resistance related to the overuse of these drugs. As far as we know, this index represents the first attempt to create such an instrument for predicting the occurrence of infections in myeloma patients.

Identification and characterization of HLA-A24-specific XBP1, CD138 (Syndecan-1) and CS1 (SLAMF7) peptides inducing antigens-specific memory cytotoxic T lymphocytes targeting multiple myeloma

X-box binding protein 1 (XBP1), CD138 (Syndecan-1) and CS1 (SLAMF7) are highly expressed antigens in cancers including multiple myeloma (MM). Here, we identify and characterize immunogenic HLA-A24 peptides derived from these antigens for potential vaccination therapy of HLA-A24+ patients with MM. The identified immunogenic HLA-A24-specific XBP1 unspliced (UN)185-193 (I S P W I L A V L), XBP1 spliced (SP)223-231 (V Y P E G P S S L), CD138265-273 (I F A V C L V G F) and CS1240-248 (L F V L G L F L W) peptides induced antigen-specific CTL with anti-MM activity in an HLA-A24 restricted manner. Furthermore, a cocktail containing the four HLA-A24 peptides evoked MM-specific CTL with distinct phenotypic profiles (CD28, CD40L, 41BB, CD38, CD69) and anti-tumor activities, evidenced by perforin upregulation, CD107a degranulation (cytotoxicity) and Th1-type cytokines (IFN-γ/IL-2/TNF-α) production in response to HLA-A24+ MM cells. The multipeptide-specific CTL included antigen-specific memory CD8+ T cells expressing both T-cell activation (CD38, CD69) and immune checkpoints antigens (CTLA, PD-1, LAG-3, TIM-3). These results provide the framework for a multipeptide vaccination therapy to induce tumor-specific CTL in HLA-A24-positive patients with myeloma and other cancers expressing these antigens.

Autologous T cells expressing the oncogenic transcription factor KLF6-SV1 prevent apoptosis of chronic lymphocytic leukemia cells

Crosstalk between leukemic cells and the tumor microenvironment is of importance in chronic lymphocytic leukemia (CLL). T cells seem to sustain the survival of CLL cells by various mechanisms. The Krüppel-like family of transcription factors (KLFs) are identified as regulators of proliferation and cell death. In the present study, we analyzed the expression of the wild type (WT) gene KLF6 and the oncogenic splice variant 1 (KLF6-SV1) at the mRNA level in subsets of T cells from CLL patients (n = 29), multiple myeloma patients (n = 6) and normal donors (n = 10). RNA Silencing was used for wtKLF6 and KLF6-SV1. Tumor cell apoptosis was measured. A significant overexpression of wtKLF6 and KLF6-SV1 in T cells of CLL patients compared to normal donors and myeloma patients was noted (p<0.002). Western blot showed that both wtKLF6 and KLF6-SV1 were expressed in purified T cells from CLL patients. KLF6-SV1 siRNA transfection induced a significant down-regulation of KLF6-SV1 in CLL T cells, which lost the capability to sustain the growth of leukemic cells. However, no such a significant effect was seen after wtKLF6 transfection of the autologous T cells. The results suggest that KLF6-SV1 may play a role in the regulation of survival CLL cells.

Innate immunity and cellular senescence: The good and the bad in the developmental and aged brain

Ongoing studies evidence cellular senescence in undifferentiated and specialized cells from tissues of all ages. Although it is believed that senescence plays a wider role in several stress responses in the mature age, its participation in certain physiological and pathological processes throughout life is coming to light. The "senescence machinery" has been observed in all brain cell populations, including components of innate immunity (e.g., microglia and astrocytes). As the beneficial versus detrimental implications of senescence is an open question, we aimed to analyze the contribution of immune responses in regulatory mechanisms governing its distinct functions in healthy (development, organogenesis, danger patrolling events) and diseased brain (glioma, neuroinflammation, neurodeneration), and the putative connection between cellular and molecular events governing the 2 states. Particularly this review offers new insights into the complex roles of senescence both as a chronological event as age advances, and as a molecular mechanism of brain homeostasis through the important contribution of innate immune responses and their crosstalk with neighboring cells in brain parenchyma. We also highlight the impact of the recently described glymphatic system and brain lymphatic vasculature in the interplay between peripheral and central immune surveillance and its potential implication during aging. This will open new ways to understand brain development, its deterioration during aging, and the occurrence of several oncological and neurodegenerative diseases.