Coinhibitory molecule PD-1 as a potential target for the immunotherapy of multiple myeloma

PD-L1 immunohistochemistry assay optimization to provide more comprehensive pathological information in classic Hodgkin lymphoma

Overexpression of PD-L1 can be a predictive marker for anti-PD-1 therapeutic efficacy in classic Hodgkin lymphoma (CHL); however, harmonization of different IHC assays remains to be accomplished, and interpretations of PD-L1 immunostaining results remain controversial in CHL. In this study, we sought to optimize the PD-L1 immunohistochemistry (IHC) assay in CHL. All tests were performed on a tumour tissue microarray established from 54 CHL cases. Three IHC antibodies (405.9A11, SP142, 22C3) for detecting PD-L1 expression were compared semi quantitatively with the RNAscope assay (No. 310035, ACD), and the difference in the expression in background immune cells (ICs) between assays and the associations of expression levels with densities of TILs/TAMs were also analysed. 405.9A11 demonstrated best specificity in HRS cells and best sensitivity in ICs. Positive expression of PD-L1 was more frequent in ICs (85.2%) than in HRS cells (48.1%). Different subgroups of background ICs, including tumour-associated macrophages (TAMs), were assessed and scored for CD4, CD8, FOXP3, and CD163 expression. PD-L1 expression on ICs was the factor most associated with the density of TAMs. 405.9A11 provided the most convincing PD-L1 expression results. Pathologists should report PD-L1 expression in a combined manner, including both the status of HRS cells and the percentage of PD-L1-positive ICs.

Monoclonal Antibodies: The Greatest Resource to Treat Multiple Myeloma

Multiple myeloma (MM) is a currently incurable hematologic cancer. This disease is characterized by immunological alterations of myeloid cells and lymphocytes. The first-line therapy involves the use of classic chemotherapy; however, many patients have a relapsed form that could evolve into a refractory MM. The new therapeutic frontiers involve the use of new monoclonal antibodies (Mab) such as daratumumab, isatuximab, and elotuzumab. In addition to monoclonal antibodies, new immunotherapies based on modern bispecific antibodies and chimeric antigen receptor (CAR) T cell therapy have been investigated. For this reason, immunotherapy represents the greatest hope for the treatment of MM. This review intends to focus the attention on the new approved antibody targets. The most important are: CD38 (daratumumab and isatuximab), SLAM7 (elotuzumab), and BCMA (belantamab mafodotin) for the treatment of MM currently used in clinical practice. Although the disease is still incurable, the future perspective is to find the best therapeutic combination among all available drugs.

BSA-AIE Nanoparticles with Boosted ROS Generation for Immunogenic Cell Death Immunotherapy of Multiple Myeloma

The main obstacle of multiple myeloma (MM) therapy is the compromised immune microenvironment, which leads to MM relapses and extramedullary disease progression. In this study, a novel strategy is reported of enhanced immunogenic cell death (ICD) immunotherapy with aggregation-induced emission (AIE) photosensitizer-loaded bovine serum albumin (BSA) nanoparticles (referred as BSA/TPA-Erdn), which can activate T cells, convert the cold tumor to hot, and reverse T cell senescence to restore the immune microenvironment for MM treatment. Loading AIE photosensitizer into the hydrophobic domain of BSA proteins significantly immobilizes the molecular geometry, which massively increases reactive oxygen species (ROS) generation and elicits a promising ICD immune response. Employing a NOD-SCID IL-2receptor gamma null mice model with MM patients' monocytes, it is shown that BSA/TPA-Erdn can simulate human dentric cell maturation, activate functional T lymphocytes, and increase additional polarization and differentiation signals to deliver a promising immunotherapy performance. Intriguingly, for the first time, it is shown that BSA/TPA-Erdn can greatly reverse T cell senescence, a main challenge in treating MM. Additionally, BSA/TPA-Erdn can effectively recruit more functional T lymphocytes into MM tumor. As a consequence, BSA/TPA-Erdn restores MM immune microenvironment and shows the best MM tumor eradication performance, which shall pave new insights for MM treatment in clinical practices.

Different expression patterns of VISTA concurrent with PD-1, Tim-3, and TIGIT on T cell subsets in peripheral blood and bone marrow from patients with multiple myeloma

V-type immunoglobulin domain-containing suppressor of T cell activation (VISTA) is considered as an immunosuppressive factor and potential therapeutic target for anticancer therapy. However, little is known about VISTA expression and its role in immunosuppression in multiple myeloma (MM). In this study, VISTA expression and co-expression with programmed cell death receptor-1 (PD-1), T cell immunoglobulin mucin-domain-containing-3 (Tim-3), and T cell immunoglobulin and ITIM domain (TIGIT) in CD3+, CD4+, CD8+, and regulatory T (Treg) cells were analyzed in patients with MM by multi-color fluorescent flow cytometry of peripheral blood (PB) and bone marrow (BM) samples from 36 patients with MM and compared to 36 PB samples and 10 BM samples from healthy individuals (HIs), which served as controls. The results demonstrated a significant increased percentage of VISTA co-expression with PD-1, Tim-3, and TIGIT in CD3+, CD4+, CD8+, and Treg cells in PB from MM patients compared with HIs. A similar trend for VISTA+CD8+ T cells was found in BM. Moreover, a trend of a high percentage on VISTA expression and co-expression in PB rather than BM was found. Furthermore, significant positive correlations existed for VISTA expression concurrent with PD-1, Tim-3, and TIGIT in T cell subsets and clinical indicators, including Revised International Staging System (R-ISS) staging of multiple myeloma, Eastern Cooperative Oncology Group (ECOG) score, and beta-2-microglobulin (β2-MG). In conclusion, higher VISTA expression concurrent with PD-1, Tim-3, and TIGIT on T cells, particularly in the PB of patients with MM, may result in T cell exhaustion and dysfunction and be closely associated with disease progression and clinical indicators. Thus, VISTA may be considered a potential target for reversing T cell exhaustion and improving T cell function in MM.

PD-L1 and PD-L2 Mutations in Pediatric Hodgkin Lymphoma: Do They Have Any Prognostic Significance?

Background: Reed-Sternberg cells can escape from the immune system by enhancement of the expression of PD-L1 and PD-L2. Objectives: The aim of the present study was to investigate the significance PD-L1 and PD-L2 gene mutations in childhood Hodgkin Lymphoma's (HL). Methods: The study included 39 pediatric classical HL cases. PD-L1 and PD-L2 mutations were determined by Sanger sequencing. Clinicopathological parameters were obtained from patients' records. Results: Eight cases (20.5%) showed p.R260C mutations, and three (7.7%) p.R234L in the exome 5 of PD-L1 gene. None of the cases had PD-L2 mutations. p.R260C mutation exhibited a significant relationship with older age and nodular sclerosing (NS) histology and was associated with longer event free survival. Conclusions: Although PD-L1 mutational status did not show statistically significance with well-established prognostic factors, our preliminary data indicate that p.R260C mutation of PD-L1 gene may be associated with longer event free survival in older patients and NS histology in pediatric HL.

Microparticles and PD1 interplay added a prognostic impact in treatment outcomes of patients with multiple myeloma

Although multiple myeloma (MM) is still considered as an incurable disease by current standards, the development of several combination therapies, and immunotherapy approaches has raised the hope towards transforming MM into an indolent, chronic disease, and possibly achieving a cure. We tried to shed light on the expression of PD1 and different Microparticles (MPs) in MM and their interplay as a mechanism of resistance to standardized treatments, in addition, find their associations with prognostic factors of symptomatic MM. Thirty patients with newly diagnosed and chemotherapy naïve active MM, along with 19 healthy participants of comparable age and sex were recruited, after diagnosis of MM; blood samples were collected from both patients and controls for flow cytometric detection of CD4+, CD8+, CD4+PD1+, and CD8+PD1+T cells, total MPs, CD138+ MPs, and platelet MPs. MM patients had statistically significant higher levels of TMPs, CD138+ MPs compared to their controls, while PMPs exhibited no significant difference between both groups. Statistically significant higher percentages of CD8+, PD1CD8+, PD1CD4+T cells were detected in patients compared to controls, while the latter group had a significantly higher percentage of CD4+T cells than MM patients, patients who did not achieve complete response, had significantly higher percentages of PMPs, CD138+MPs, PD1+CD8+, PD1+CD4+, and CD8+T cells (cutoff values = 61, 10.6, 13.5, 11.3 and 20.1 respectively), (p-values = 0.002, 0.003, 0.017, 0.001 and 0.008 respectively). Microparticles and PD1 expressions were associated with proliferative potential and resistance to Bortezomib-based treatments, our results suggested that they played a crucial role in myeloma progression.

Bone marrow-derived mesenchymal stem cells inhibit CD8+ T cell immune responses via PD-1/PD-L1 pathway in multiple myeloma

High expression of the inhibitory receptor programmed cell death ligand 1 (PD-L1) on tumor cells and tumor stromal cells have been found to play a key role in tumor immune evasion in several human malignancies. However, the expression of PD-L1 on bone marrow mesenchymal stem cells (BMSCs) and whether the programmed cell death 1 (PD-1)/PD-L1 signal pathway is involved in the BMSCs versus T cell immune response in multiple myeloma (MM) remains poorly defined. In this study, we explored the expression of PD-L1 on BMSCs from newly diagnosed MM (NDMM) patients and the role of PD-1/PD-L1 pathway in BMSC-mediated regulation of CD8⁺ T cells. The data showed that the expression of PD-L1 on BMSCs in NDMM patients was significantly increased compared to that in normal controls (NC) (18·81 ± 1·61 versus 2·78± 0·70%; P < 0·001). Furthermore, the PD-1 expression on CD8⁺ T cells with NDMM patients was significantly higher than that in normal controls (43·22 ± 2·98 versus 20·71 ± 1·08%; P < 0·001). However, there was no significant difference in PD-1 expression of CD4⁺ T cells and natural killer (NK) cells between the NDMM and NC groups. Additionally, the co-culture assays revealed that BMSCs significantly suppressed CD8⁺ T cell function. However, the PD-L1 inhibitor effectively reversed BMSC-mediated suppression in CD8⁺ T cells. We also found that the combination of PD-L1 inhibitor and pomalidomide can further enhance the killing effect of CD8⁺ T cells on MM cells. In summary, our findings demonstrated that BMSCs in patients with MM may induce apoptosis of CD8⁺ T cells through the PD-1/PD-L1 axis and inhibit the release of perforin and granzyme B from CD8⁺ T cells to promote the immune escape of MM.

Boosting Immunity against Multiple Myeloma

Despite the improvement of patient's outcome obtained by the current use of immunomodulatory drugs, proteasome inhibitors or anti-CD38 monoclonal antibodies, multiple myeloma (MM) remains an incurable disease. More recently, the testing in clinical trials of novel drugs such as anti-BCMA CAR-T cells, antibody-drug conjugates or bispecific antibodies broadened the possibility of improving patients' survival. However, thus far, these treatment strategies have not been able to steadily eliminate all malignant cells, and the aim has been to induce a long-term complete response with minimal residual disease (MRD)-negative status. In this sense, approaches that target not only myeloma cells but also the surrounding microenvironment are promising strategies to achieve a sustained MRD negativity with prolonged survival. This review provides an overview of current and future strategies used for immunomodulation of MM focusing on the impact on bone marrow (BM) immunome.

Belantamab mafodotin in combination with novel agents in relapsed/refractory multiple myeloma: DREAMM-5 study design

Belantamab mafodotin (belamaf) is a BCMA-targeted antibody-drug conjugate recently approved as monotherapy for adults with relapsed/refractory multiple myeloma who have received ≥4 prior therapies. Belamaf binds to BCMA and eliminates myeloma cells by multimodal mechanisms of action. The cytotoxic and potential immunomodulatory properties of belamaf have led to novel combination studies with other anticancer therapies. Here, we describe the rationale and design of DREAMM-5, an ongoing Phase I/II platform study evaluating the safety and efficacy of belamaf combined with novel agents, including GSK3174998 (OX40 agonist), feladilimab (an ICOS; GSK3359609), nirogacestat (a gamma-secretase inhibitor; PF-03084014) and dostarlimab (a PD-1 blocker) versus belamaf monotherapy for patients with relapsed/refractory multiple myeloma. Clinical trial registration: NCT04126200 (ClinicalTrials.gov).

Real-world data combined with studies on Regulatory B Cells for newly diagnosed Multiple Myeloma from a tertiary referral Hospital in South-Western China

Multiple myeloma (MM) is a heterogeneous disease that remains incurable with significant interpatient variability in outcomes. Regulatory B cells (Bregs) were observed to be involved into specific defects in MM. Here, we provide our risk-adapted approach to newly diagnosed MM (NDMM), combining with the fundamental dysfunction of Bregs. We reported one hundred consecutive patients with NDMM from South-Western China, primarily treated with bortezomib plus dexamethasone with or without a 3rd agent, were enrolled from 2017. Bone marrow aspirates were obtained and flow cytometry (FCM) was used to quantify the percentage of Bregs from the bone marrow. The correlation between Bregs and clinical characters were further analyzed. This study found using bortezomib plus dexamethasone as backbone showed promising efficacy with acceptable tolerability in NDMM. The relatively compromised progression free survival (PFS) points to the essential synergy of bortezomib and lenalidomide here. This study also found that altered proportions of Bregs were closely correlated with treatment efficacy and prognosis in MM. Further understanding of Bregs biology might provide new opportunities to develop immunotherapy, which could prove beneficial in treating MM.

The Immune Microenvironment in Multiple Myeloma: Friend or Foe?

Simple Summary

The crosstalk between multiple myeloma and immune cells within the bone marrow niche has been identified as an emerging hallmark of this hematological disease. As our knowledge on this interplay increases, it becomes more evident that successful treatment approaches need to boost the body’s natural defenses through immunotherapy. The present review will focus on the mechanisms by which myeloma cancer cells turn immune populations into their “partners in crime”. Additionally, we will provide an overview of currently ongoing pre-clinical studies targeting the bone marrow immune microenvironment.

Abstract

Multiple myeloma (MM) is one of the most prevalent hematological cancers worldwide, characterized by the clonal expansion of neoplastic plasma cells in the bone marrow (BM). A combination of factors is implicated in disease progression, including BM immune microenvironment changes. Increasing evidence suggests that the disruption of immunological processes responsible for myeloma control ultimately leads to the escape from immune surveillance and resistance to immune effector function, resulting in an active form of myeloma. In fact, one of the hallmarks of MM is the development of a permissive BM milieu that provides a growth advantage to the malignant cells. Consequently, a better understanding of how myeloma cells interact with the BM niche compartments and disrupt the immune homeostasis is of utmost importance to develop more effective treatments. This review focuses on the most up-to-date knowledge regarding microenvironment-related mechanisms behind MM immune evasion and suppression, as well as promising molecules that are currently under pre-clinical tests targeting immune populations.

Determination of PD-1 expression in peripheral blood cells in patients with endometriosis

In patients with endometriosis, ectopic endometrial tissues can escape from immune system control and survive in other tissues. The pathophysiology of endometriosis is still not fully understood. In this study, we aimed to clarify the pathophysiology of endometriosis, which is thought to be a benign but infiltrative cancer type, which has many similarities with cancer biology by determining PD-1 expression in patients with endometriosis. In this study, n = 73 cases who underwent surgery or examination at the Obstetrics and Gynecology Clinic of Sivas Cumhuriyet University Faculty of Medicine and diagnosed as endometriosis in the biopsy material taken with the pre-diagnosis of endometriosis constituted the patient group. The control group consisted of n = 64 healthy subjects without concomitant malignancy or chronic inflammatory disease. Venous whole blood samples were obtained from the study groups. PD-1 and PD-L1 levels were determined by the ELISA method from serum and plasma samples. PD-1 gene expression level was determined by RT-PCR. The PD-1 level was found to be approximately 350 ± 150 ng/L and 45 ± 17 ng/L in endometriosis and control group, respectively. While the PD-L1 level was approximately 760 ± 108 ng/L in the patients, this level was 140 ± 14 ng/L in the controls. According to the RT-PCR results, the expression of the PD-1 gene 10 times higher compared to the controls. Conclusion: The identified increase of PD-1 levels and gene expression in endometriosis groups show that immunotherapy may be used in the treatment of endometriosis.

Novel progresses of chimeric antigen receptor (CAR) T cell therapy in multiple myeloma

Multiple myeloma (MM) is a malignant proliferative disease of plasma cells, which leads to suppressed hematopoietic and osteolytic diseases. Despite the use of traditional chemotherapy, hematopoietic stem cell transplantation (HSCT) and targeted drugs, MM still cannot be completely cured. In recent years, chimeric antigen receptor (CAR) T cells have revolutionized immunotherapy and cancer treatment. The great success of CAR-T cells in leukemia and lymphoma has promoted its development in MM. The primary requisite for developing clinically effective CAR-T cells suitable for MM is to identify the appropriate targets. In early clinical trials, CAR-T cells targeting B-cell maturation antigen (BCMA) have shown significant anti-MM activity. Currently popular targets in clinical research and preclinical research include CD138, CD38, CS1, CD19, κ light chain, CD56, CD44v6, Lewis Y, NY-ESO-1, CD229, etc. Common toxicities such as cytokine release syndrome (CRS) and neurotoxicity also occur but controllable. MM cells are mainly localized in bone marrow, therefore, the bone marrow microenvironment has a significant effect on the therapeutic effect of CAR-T cells. Targeting both MM cells and the bone marrow microenvironment is currently the most promising treatment. In this review, we provide a comprehensive overview of CAR-T cell therapy in MM, as well as outline potential targets and methods that can overcome local immunosuppression and improve the efficacy of CAR-T cells.

Activatable Polymer Nanoenzymes for Photodynamic Immunometabolic Cancer Therapy

Tumor immunometabolism contributes substantially to tumor proliferation and immune cell activity, and thus plays a crucial role in the efficacy of cancer immunotherapy. Modulation of immunometabolism to boost cancer immunotherapy is mostly based on small-molecule inhibitors, which often encounter the issues of off-target adverse effects, drug resistance, and unsustainable response. In contrast, enzymatic therapeutics can potentially bypass these limitations but has been less exploited. Herein, an organic polymer nanoenzyme (SPNK) with near-infrared (NIR) photoactivatable immunotherapeutic effects is reported for photodynamic immunometabolic therapy. SPNK is composed of a semiconducting polymer core conjugated with kynureninase (KYNase) via PEGylated singlet oxygen (¹ O₂ ) cleavable linker. Upon NIR photoirradiation, SPNK generates ¹ O₂ not only to exert photodynamic effect to induce the immunogenic cell death of cancer, but also to unleash KYNase and trigger its activity to degrade the immunosuppressive kynurenine (Kyn). Such a combinational effect mediated by SPNK promotes the proliferation and infiltration of effector T cells, enhances systemic antitumor T cell immunity, and ultimately permits inhibition of both primary and distant tumors in living mice. Therefore, this study provides a promising photodynamic approach toward remotely controlled enzymatic immunomodulation for improved anticancer therapy.

Immune checkpoint inhibitors in multiple myeloma: A review of the literature

The human immune system has structures called checkpoints controlling the intensity and the duration of immune responses. In the last years, studies and research have been concentrating on creating new drugs recognized as Immune Checkpoint Inhibitors that have been launched in clinical practice to treat patients with several types of cancer, including multiple myeloma. Multiple myeloma is characterized by dysfunctions in humoral and cellular immunity altering immune surveillance and support tumor advancement to escape: in particular, the disease causes the inactivation of T-cells because of their bond with antigens shown in cancer cells. It can be stated that checkpoint inhibitors "inhibit the inhibition" of cell-mediated immunity and induce tumor cells apoptosis. In this review we have focused our attention on summarizing current information about Immune Checkpoint Inhibitors which have been developed in the last years to treat multiple myeloma; particular consideration will be dedicated to describing their mechanism of action and their potential use in therapy. Further investigations are necessary in this field to define the possibility of an effective and safe inclusion of these drugs in clinical practice.

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.

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.

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.

Prognostic Impact of Adenosine Receptor 2 (A2aR) and Programmed Cell Death Ligand 1 (PD-L1) Expression in Colorectal Cancer

Background

Programmed cell death ligand 1 (PD-L1) is a key inhibitor to the immune response by binding to the specific receptor PD-1. Adenosine receptor 2 (A2aR) can play an immunosuppressive role in tumor microenvironment by binding to its ligand adenosine (ADO). However, the expression of these two markers has been rarely studied in colorectal cancer simultaneously.

Materials and Methods

We, respectively, collected tumor and adjacent nontumor tissue specimens of 204 patients with colorectal cancer. The expressions of PD-L1 and A2aR were detected by immunohistochemistry. The association among their expressions with clinicopathological characteristics and prognostic parameters were analyzed as well.

Results

The expressions of PD-L1 and A2aR in tumor tissues were both higher than those in matched adjacent nontumor tissues. PD-L1 expression was significantly correlated with lymph node metastasis and tumor TNM stage. A2aR expression was significantly correlated with tumor size, depth of tumor invasion, and TNM stage. Univariate analysis showed that the high expressions of PD-L1 and A2aR were inversely correlated with the overall survival, respectively. Multivariate analysis further confirmed that both of them were independent prognostic markers for patients.

Conclusion

The results of this study suggested that the high expressions of PD-L1 and A2aR were associated with a poor prognosis of colorectal cancer. Coinhibition of these two proteins may be a new breakthrough in the treatment of this disease.

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.

Treatment of Lymphoid and Myeloid Malignancies by Immunomodulatory Drugs

Thalidomide and its derivatives (lenalidomide, pomalidomide, avadomide, iberdomide hydrochoride, CC-885 and CC-90009) form the family of immunomodulatory drugs (IMiDs). Lenalidomide (CC5013, Revlimid®) was approved by the US FDA and the EMA for the treatment of multiple myeloma (MM) patients, low or intermediate-1 risk transfusion-dependent myelodysplastic syndrome (MDS) with chromosome 5q deletion [del(5q)] and relapsed and/or refractory mantle cell lymphoma following bortezomib. Lenalidomide has also been studied in clinical trials and has shown promising activity in chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL). Lenalidomide has anti-inflammatory effects and inhibits angiogenesis. Pomalidomide (CC4047, Imnovid® [EU], Pomalyst® [USA]) was approved for advanced MM insensitive to bortezomib and lenalidomide. Other IMiDs are in phases 1 and 2 of clinical trials. Cereblon (CRBN) seems to have an important role in IMiDs action in both lymphoid and myeloid hematological malignancies. Cereblon acts as the substrate receptor of a cullin-4 really interesting new gene (RING) E3 ubiquitin ligase CRL4CRBN. This E3 ubiquitin ligase in the absence of lenalidomide ubiquitinates CRBN itself and the other components of CRL4CRBN complex. Presence of lenalidomide changes specificity of CRL4CRBN which ubiquitinates two transcription factors, IKZF1 (Ikaros) and IKZF3 (Aiolos), and casein kinase 1α (CK1α) and marks them for degradation in proteasomes. Both these transcription factors (IKZF1 and IKZF3) stimulate proliferation of MM cells and inhibit T cells. Low CRBN level was connected with insensitivity of MM cells to lenalidomide. Lenalidomide decreases expression of protein argonaute-2, which binds to cereblon. Argonaute-2 seems to be an important drug target against IMiDs resistance in MM cells. Lenalidomide decreases also basigin and monocarboxylate transporter 1 in MM cells. MM cells with low expression of Ikaros, Aiolos and basigin are more sensitive to lenalidomide treatment. The CK1α gene (CSNK1A1) is located on 5q32 in commonly deleted region (CDR) in del(5q) MDS. Inhibition of CK1α sensitizes del(5q) MDS cells to lenalidomide. CK1α mediates also survival of malignant plasma cells in MM. Though, inhibition of CK1α is a potential novel therapy not only in del(5q) MDS but also in MM. High level of full length CRBN mRNA in mononuclear cells of bone marrow and of peripheral blood seems to be necessary for successful therapy of del(5q) MDS with lenalidomide. While transfusion independence (TI) after lenalidomide treatment is more than 60% in MDS patients with del(5q), only 25% TI and substantially shorter duration of response with occurrence of neutropenia and thrombocytopenia were achieved in lower risk MDS patients with normal karyotype treated with lenalidomide. Shortage of the biomarkers for lenalidomide response in these MDS patients is the main problem up to now.

Therapeutic antibodies for multiple myeloma

In recent years, many antibody therapies for multiple myeloma have been developed. Antibodies against SLAMF7, CD38, B-cell maturation antigen and PD-1 have been developed and clinical trials are currently under way. As of July 2017, antibodies clinically available in Japan for the treatment of multiple myeloma are elotuzumab against SLAMF7 and daratumumab against CD38. Elotuzumab is a humanized IgG1-kappa monoclonal antibody targeting human SLAMF7. SLAMF7 is a cell surface glycoprotein receptor highly expressed on multiple myeloma cells, and it is also expressed on natural killer cells and is critical for natural killer function. Binding of elotuzumab to natural killer cells leads to activation of natural killer cells, resulting in antibody-dependent cell-mediated cytotoxicity of elotuzumab-bound multiple myeloma cells, but not complement-dependent cytotoxicity. The result of a randomized phase III trial of elotuzumab+lenalidomide+dexamethasone (ELOQUENT-2) reduced the risk of disease progression/death by 30% vs lenalidomide+dexamethasone in relapse/refractory multiple myeloma. Daratumumab is a human anti-CD38 IgG1-kappa antibody. CD38 is expressed ubiquitously virtually in all tissues that are highly expressed on plasma cells and it represents an attractive target for immunotherapy using monoclonal antibodies. In the phase III CASTOR trial, patients treated with daratumumab+bortezomib+dexamethasone had a better CR rate and progression-free survival rate compared with bortezomib+dexamethasone-treated patients (29% vs 10%, median progression-free survival: 16.7 vs 7.1 months, respectively). Moreover, in the phase III POLLUX trial, patients treated with daratumumab+lenalidomide+dexamethasone had a better response and progression-free survival (CRR or better: 55% vs 23%, 30-month progression-free survival: 58% vs 35%), compared with lenalidomide+dexamethasone-treated patients.

HGF/MET and the Immune System: Relevance for Cancer Immunotherapy

An overactivation of hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor (MET) axis promotes tumorigenesis and tumor progression in various cancer types. Research data recently evidenced that HGF/MET signaling is also involved also in the immune response, mainly modulating dendritic cells functions. In general, the pathway seems to play an immunosuppressive role, thus hypothesizing that it could constitute a mechanism of primary and acquired resistance to cancer immunotherapy. Recently, some approaches are being developed, including drug design and cell therapy to combine MET and programmed cell death receptor-1 (PD-1)/programmed cell death receptor-ligand 1 (PD-L1) inhibition. This approach could represent a new weapon in cancer therapy in the future.

Murine pre-B-cell ALL induces T-cell dysfunction not fully reversed by introduction of a chimeric antigen receptor

Adoptive transfer of patient-derived T cells modified to express chimeric antigen receptors (CARTs) has demonstrated dramatic success in relapsed/refractory pre-B-cell acute lymphoblastic leukemia (ALL), but response and durability of remission requires exponential CART expansion and persistence. Tumors are known to affect T-cell function, but this has not been well studied in ALL and in the context of chimeric antigen receptor (CAR) expression. Using TCF3/PBX1 and MLL-AF4-driven murine ALL models, we assessed the impact of progressive ALL on T-cell function in vivo. Vaccines protect against TCF3/PBX1.3 but were ineffective when administered after leukemia injection, suggesting immunosuppression induced early during ALL progression. T cells from leukemia-bearing mice exhibited increased expression of inhibitory receptors, including PD1, Tim3, and LAG3, and were dysfunctional following adoptive transfer in a model of T-cell receptor (TCR)-dependent leukemia clearance. Although expression of inhibitory receptors has been linked to TCR signaling, pre-B-cell ALL induced inhibitory receptor expression, at least in part, in a TCR-independent manner. Finally, introduction of a CAR into T cells generated from leukemia-bearing mice failed to fully reverse poor in vivo function.

The T-win® technology: immune-modulating vaccines

The T-win® technology is an innovative investigational approach designed to activate the body's endogenous anti-regulatory T cells (anti-Tregs) to target regulatory as well as malignant cells. Anti-Tregs are naturally occurring T cells that can directly react against regulatory immune cells because they recognize proteins that these targets express, including indoleamine 2,3-dioxygenase (IDO), tryptophan 2,6-dioxygenase, arginase, and programmed death ligand 1 (PD-L1). The T-win® technology is characterized by therapeutic vaccination with long peptide epitopes derived from these antigens and therefore offers a novel way to target genetically stable cells with regular human leukocyte antigen expression in the tumor microenvironment. The T-win® technology thus also represents a novel way to attract pro-inflammatory cells to the tumor microenvironment where they can directly affect immune inhibitory pathways, potentially altering tolerance to tumor antigens. The modification of an immune regulatory environment into a pro-inflammatory milieu potentiates effective anti-tumor T cell responses. Many regulatory immune cells may be reverted into effector cells given the right stimulus. Because T-win® technology is based on the immune-modulatory function of the vaccines, the vaccines activate both CD4 and CD8 anti-Tregs. Of importance, in clinical trials, vaccinations against IDO or PD-L1 to potentiate anti-Tregs have so far proved to be safe, with minimal toxicity.

Biomarkers for checkpoint inhibition in hematologic malignancies

In the past few years we have seen remarkable paradigm shifts in the treatment of many solid tumors due to the introduction of inhibitors targeting immune checkpoints such as PD-1/PD-L1 and CTLA-4. Recent results indicate that checkpoint inhibition also represents a very promising approach for certain types of hematologic malignancies. Unfortunately, treatment with checkpoint inhibitors is also associated with substantial toxicities and high costs and only a subset of patients appears to derive clinical benefit from these treatments. This demonstrates the urgent need for biomarkers for the identification of patient populations that are likely to respond to this type of therapy and/or have fewer side effects. Here, we have reviewed available information on the prognostic and predictive value of biomarkers for anti-CTLA-4 and anti-PD-1/PD-L1 as the most commonly used checkpoint inhibitors. There are currently no reliable biomarkers capable of predicting responses to anti-CTLA-4 agents, such as ipilimumab, in hematologic malignancies. Certain polymorphisms in the CTLA-4 gene, however, seem to have an impact on the patients' outcome, especially in the case of chronic lymphocytic leukemia (CLL). There is now sufficient data supporting PD-L1 expression levels in the tumor tissue as an independent prognostic factor in B cell lymphomas such as diffuse large B-cell lymphoma (DLBCL). Overexpression of PD-L1 in the tumor tissue and elevated serum levels of soluble PD-L1 may also represent adverse prognostic factors in certain subtypes of T cell lymphomas. Finally, expression levels of PD-L1 also seem to predict responses to anti-PD-1/PD-L1 approaches in patients with Hodgkin lymphoma. Future studies will have to further delineate the prognostic/predictive role of PD-L1 expression as a biomarker in hematologic malignancies and may be able to identify confounding variables, which will hopefully to some extent be generalizable to other types of anti-tumor immunotherapies.

Bone marrow-derived mesenchymal stem cells promote cell proliferation of multiple myeloma through inhibiting T cell immune responses via PD-1/PD-L1 pathway

OBJECTIVES

This study aims to explore the effect of bone marrow mesenchymal stem cells (BMSCs) on multiple myeloma (MM) development and the underlying mechanism.

MATERIALS AND METHODS

BMSCs from C57BL/6 J mice were isolated and the third passage was used for subsequent experiments. Additionally, a series of in vitro transwell coculture assays were performed to explore the effects of BMSCs on the proliferation of MM cells 5TGM1 and CD4+ T cells. Furthermore, a 5TGM1-induced MM mice model was established. Moreover, PD-L1 shRNA was transfected into BMSCs to investigate whether PD-1/PD-L1 pathway involved in BMSCs-mediated regulation of T cells and MM growth.

RESULTS

Data revealed that BMSCs significantly promoted 5TGM1 proliferation in a dose-dependent manner. Furthermore, BMSCs administration exerted stimulatory effects on MM development in terms of shortening the mouse survival rate, promoting tumor growth, and enhancing inflammatory infiltration in the MM model mice. Moreover, BMSCs decreased the percentage of Th1 and Th17 cells, whereas increased that of Th2 and Treg cells. Their corresponding cytokines of these T cell subsets showed similar alteration in the presence of BMSCs. Additionally, BMSCs significantly suppressed CD4+ T cell proliferation. We also found that PD-L1 shRNA inhibited 5TGM1 proliferation likely through activation of CD4+ T cells. Further in vivo experiments confirmed that PD-L1 inhibition attenuated BMSCs-induced MM growth, inflammation infiltration and imbalance of Th1/Th2 and Th17/Treg.

CONCLUSION

In summary, our findings demonstrated that BMSCs promoted cell proliferation of MM through inhibiting T cell immune responses via PD-1/PD-L1 pathway.

Soluble PD-L1: A biomarker to predict progression of autologous transplantation in patients with multiple myeloma

Autologous hematopoietic stem cell transplantation (AuHSCT) is standard in treating eligible multiple myeloma (MM) patients. However, the outcome after treatment is highly variable. We used ELISA to analyze the levels of soluble PD-L1 (suPD-L1) in bone marrow (BM) plasma from 61 patients with MM at 100 days after AuHSCT. Patients were classified into high (H) and normal-to-low (NL) groups depending on their suPD-L1 levels. Among patients who had a very good partial response (VGPR) or better after AuHSCT, those in the H-group had a shorter response period (RpSCT) as well as shorter overall survival (OS) than those in the NL-group. Multivariate analyses confirmed that a high suPD-L1 level and high-risk cytogenetic abnormalities are independent factors for RpSCT. Our data suggest that suPD-L1 in the BM plasma of MM patients who have VGPR or better after AuHSCT could be used as a biomarker to predict outcome.

Activity of pembrolizumab in relapsed/refractory NK/T-cell lymphoma

Natural killer/T-cell lymphoma (NKTCL) is a rare subtype of non-Hodgkin lymphoma that is associated with a poor outcome. Currently, the treatment needs of NKTCL remain unmet, and efforts to further improve treatment are urgently needed. Herein, seven patients with NKTCL who failed to respond to various types of chemotherapies were treated with the anti-programmed death 1 (anti-PD-1) antibody pembrolizumab at 100 mg every 3 weeks. After a median of four cycles of treatment (range 2-18), four out of seven patients responded (two complete response, two partial response, overall response rate 57%). Expression of PD1-ligand available was 50, 20, 30, 70, and 30% of five patients respectively. It is negative in one patient and not tested in one patient. Adverse events, which mostly ranged from grade I to grade III, were tolerable and could be safely handled, although immune-related pneumonitis was notable. Overall, PD-1 blockade with pembrolizumab represents a favorable strategy for the treatment of refractory/relapsed NKTCL.

Monoclonal Antibody Therapies for Hematological Malignancies: Not Just Lineage-Specific Targets

Today, monoclonal antibodies (mAbs) are a widespread and necessary tool for biomedical science. In the hematological cancer field, since rituximab became the first mAb approved by the Food and Drug Administration for the treatment of B-cell malignancies, a number of effective mAbs targeting lineage-specific antigens (LSAs) have been successfully developed. Non-LSAs (NLSAs) are molecules that are not restricted to specific leukocyte subsets or tissues but play relevant pathogenic roles in blood cancers including the development, proliferation, survival, and refractoriness to therapy of tumor cells. In consequence, efforts to target NLSAs have resulted in a plethora of mAbs-marketed or in development-to achieve different goals like neutralizing oncogenic pathways, blocking tumor-related chemotactic pathways, mobilizing malignant cells from tumor microenvironment to peripheral blood, modulating immune-checkpoints, or delivering cytotoxic drugs into tumor cells. Here, we extensively review several novel mAbs directed against NLSAs undergoing clinical evaluation for treating hematological malignancies. The review focuses on the structure of these antibodies, proposed mechanisms of action, efficacy and safety profile in clinical studies, and their potential applications in the treatment of hematological malignancies.

Immune Therapies in Multiple Myeloma

Treatment paradigms have changed rapidly for multiple myeloma, and immune therapies have taken center stage. Advances in therapies for myeloma have led to a dramatic improvement in the survival of patients with this incurable malignancy. The immune system is significantly impaired in patients with myeloma as a result of the disease leading to suppression of normal plasma cells as well the negative effects on cellular immunity. Given this scenario, immune approaches have not been successful until recently. Monoclonal antibodies directed against CD38 (daratumumab) and SLAMF7 (elotuzumab) are already in the clinic, and several other antibodies directed against different plasma cell antigens are under evaluation. Although immune checkpoint inhibition with PD-1 inhibitors had no clinical efficacy when the inhibitors were used as single agents, it has led to some dramatic results when the inhibitors are combined with immunomodulatory drugs such as lenalidomide and pomalidomide. Vaccination strategies have shown in vivo immune responses but no clear clinical efficacy. Newer approaches to vaccination with multiple antigens, used in combinations with immunomodulatory drugs and in the setting of minimal residual disease, have all increased possibility of this approach succeeding. Ex vivo effector cell expansion also appears to be promising and is in clinical trials. Finally, a chimeric antigen receptor T-cell approach appears to have some promise based on isolated reports of success and remains an area of intense investigation. Immune-based approaches can potentially augment or even supplant some of the current approaches and, given the low toxicity profile, may hold great potential in the early treatment of precursor-stage diseases. Clin Cancer Res; 22(22); 5453-60. ©2016 AACR SEE ALL ARTICLES IN THIS CCR FOCUS SECTION, "MULTIPLE MYELOMA MULTIPLYING THERAPIES".

The bone-marrow niche in MDS and MGUS: implications for AML and MM

Several haematological malignancies, including multiple myeloma (MM) and acute myeloid leukaemia (AML), have well-defined precursor states that precede the development of overt cancer. MM is almost always preceded by monoclonal gammopathy of undetermined significance (MGUS), and at least a quarter of all patients with myelodysplastic syndromes (MDS) have disease that evolves into AML. In turn, MDS are frequently anteceded by clonal haematopoiesis of indeterminate potential (CHIP). The acquisition of additional genetic and epigenetic alterations over time clearly influences the increasingly unstable and aggressive behaviour of neoplastic haematopoietic clones; however, perturbations in the bone-marrow microenvironment are increasingly recognized to have key roles in initiating and supporting oncogenesis. In this Review, we focus on the concept that the haematopoietic neoplasia-microenvironment relationship is an intimate rapport between two partners, provide an overview of the evidence supporting a role for the bone-marrow niche in promoting neoplasia, and discuss the potential for niche-specific therapeutic targets.

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

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

Role of Galectins in Multiple Myeloma

Galectins are a family of lectins that bind β-galactose-containing glycoconjugates and are characterized by carbohydrate-recognition domains (CRDs). Galectins exploit several biological functions, including angiogenesis, regulation of immune cell activities and cell adhesion, in both physiological and pathological processes, as tumor progression. Multiple myeloma (MM) is a plasma cell (PC) malignancy characterized by the tight adhesion between tumoral PCs and bone marrow (BM) microenvironment, leading to the increase of PC survival and drug resistance, MM-induced neo-angiogenesis, immunosuppression and osteolytic bone lesions. In this review, we explore the expression profiles and the roles of galectin-1, galectin-3, galectin-8 and galectin-9 in the pathophysiology of MM. We focus on the role of these lectins in the interplay between MM and BM microenvironment cells showing their involvement in MM progression mainly through the regulation of PC survival and MM-induced angiogenesis and osteoclastogenesis. The translational impact of these pre-clinical pieces of evidence is supported by recent data that indicate galectins could be new attractive targets to block MM cell growth in vivo and by the evidence that the expression levels of LGALS1 and LGALS8, genes encoding for galectin-1 and galectin-8 respectively, correlate to MM patients’ survival.

Emerging options in multiple myeloma: targeted, immune, and epigenetic therapies

Considerable progress has been made in the treatment of multiple myeloma in the past decade with median survival for the disease improving significantly. This has come through a combination of better understanding of the disease biology and coordinated research into new treatment approaches including better supportive care. However, patients eventually become refractory to available treatments and succumb to the disease, highlighting the need to develop new treatment approaches. The genetic heterogeneity in the disease and clonal evolution under treatment pressure underlie the development of resistance, underscoring the need to develop more effective therapies that can eradicate the disease at initial treatment as well as the need for new classes of drugs with varying mechanisms of action. To this end, there has been intense focus on exploring novel approaches to therapy including small-molecule inhibitors targeting specific abnormalities, immune therapies including monoclonal antibodies and adaptive T-cell therapy, as well as epigenetic approaches. Although many of these drugs are in the early stages of clinical development, the early data appear to be very promising. Many of these drugs can be safely and effectively combined with the current treatment classes such as proteasome inhibitors and immunomodulatory drugs, further enhancing the treatment options for myeloma.

Oncolytic virotherapy as an immunotherapeutic strategy for multiple myeloma

Multiple Myeloma (MM), a clonal malignancy of antibody-producing plasma cells, is the second most common hematologic malignancy and results in significant patient morbidity and mortality. The high degree of immune dysregulation in MM, including T cell imbalances and up-regulation of immunosuppressive checkpoint proteins and myeloid derived suppressor cells, allows this malignancy to escape from host immune control. Despite advances in the therapeutic landscape of MM over the last decade, including the introduction of immunomodulatory drugs, the prognosis for this disease is poor, with less than 50% of patients surviving 5 years. Thus, novel treatment strategies are required. Oncolytic viruses (OV) are a promising new class of therapeutics that rely on tumour specific oncolysis and the generation of a potent adaptive anti-tumour immune response for efficacy. To date, a number of OV have shown efficacy in pre-clinical studies of MM with three reaching early phase clinical trials. OVs represent a rational therapeutic strategy for MM based on (1) their tumour tropism, (2) their ability to potentiate anti-tumour immunity and (3) their ability to be rationally combined with other immunotherapeutic agents to achieve a more robust clinical response.

Activation of NK cells and disruption of PD-L1/PD-1 axis: two different ways for lenalidomide to block myeloma progression

Natural Killer (NK) cells play a critical role against tumor cells in hematological malignancies. Their activating receptors are essential in tumor cell killing. In Multiple Myeloma (MM) patients, NK cell differentiation, activation and cytotoxic potential are strongly impaired leading to MM escape from immune surveillance in tissues and bone marrow. Mechanisms used by MM to affect NK cell functions are mediated by the release of soluble factors, the expression of activating and inhibitory NK cell ligands, and the expression of immune check-point inhibitors. Lenalidomide represents an efficient clinical approach in MM treatment to improve patients' survival. Lenalidomide does not only promotes tumor apoptosis, but also stimulates T and NK cells, thereby facilitating NK-mediated tumor recognition and killing. This occurs since Lenalidomide acts on several critical points: stimulates T cell proliferation and cytokine secretion; decreases the expression of the immune check-point inhibitor Programmed Death-1 (PD-1) on both T and NK cells in MM patients; decreases the expression of both PD-1 and PD-L1 on MM cells; promotes MM cell death and abrogates MM/stromal microenvironment cross-talk, a process known to promote the MM cell survival and proliferation. This leads to the inhibition of the negative signal induced by PD-1/PD-L1 axis on NK cells, restoring NK cell cytotoxic functions. Given the importance of an effective immune response to counteract the MM progression and the promising approaches using anti-PD-1/PD-L1 strategies, we will discuss in this review how Lenalidomide could represent an adequate approach to re-establish the recognition against MM by exhausted NK cell.

Discovery and application of immune biomarkers for hematological malignancies

INTRODUCTION

Hematological malignancies originate and progress in primary and secondary lymphoid organs, where they establish a uniquely immune-suppressive tumour microenvironment. Although high-throughput transcriptomic and proteomic approaches are being employed to interrogate immune surveillance and escape mechanisms in patients with solid tumours, and to identify actionable targets for immunotherapy, our knowledge of the immunological landscape of hematological malignancies, as well as our understanding of the molecular circuits that underpin the establishment of immune tolerance, is not comprehensive. Areas covered: This article will discuss how multiplexed immunohistochemistry, flow cytometry/mass cytometry, proteomic and genomic techniques can be used to dynamically capture the complexity of tumour-immune interactions. Moreover, the analysis of multi-dimensional, clinically annotated data sets obtained from public repositories such as Array Express, TCGA and GEO is crucial to identify immune biomarkers, to inform the rational design of immune therapies and to predict clinical benefit in individual patients. We will also highlight how artificial neural network models and alternative methodologies integrating other algorithms can support the identification of key molecular drivers of immune dysfunction. Expert commentary: High-dimensional technologies have the potential to enhance our understanding of immune-cancer interactions and will support clinical decision making and the prediction of therapeutic benefit from immune-based interventions.

Adoptive cell therapy in multiple Myeloma

INTRODUCTION

Recent breakthrough advances in Multiple Myeloma (MM) immunotherapy have been achieved with the approval of the first two monoclonal antibodies, elotuzumab and daratumumab. Adoptive cell therapy (ACT) represents yet another, maybe the most powerful modality of immunotherapy, in which allogeneic or autologous effector cells are expanded and activated ex vivo followed by their re-infusion back into patients. Infused effector cells belong to two categories: naturally occurring, non-engineered cells (donor lymphocyte infusion, myeloma infiltrating lymphocytes, deltagamma T cells) or genetically- engineered antigen-specific cells (chimeric antigen receptor T or NK cells, TCR-engineered cells). Areas covered: This review article summarizes our up-to-date knowledge on ACT in MM, its promises, and upcoming strategies to both overcome its toxicity and to integrate it into future treatment paradigms. Expert opinion: Early results of clinical studies using CAR T cells or TCR- engineered T cells in relapsed and refractory MM are particularly exciting, indicating the potential of long-term disease control or even cure. Despite several caveats including toxicity, costs and restricted availability in particular, these forms of immunotherapy are likely to once more revolutionize MM therapy.

The immune checkpoint molecule V-set Ig domain-containing 4 is an independent prognostic factor for multiple myeloma

Multiple myeloma (MM) remains as an incurable disease, despite recent substantial improvements in treatment. Therefore, development of novel biomarkers for risk stratification and new therapeutic targets are imperative. One of the emerging treatments for MM is the immune checkpoint blockades. V-set Ig domain-containing 4 (VSIG4) is a lately studied B7-related immune checkpoint modulator. We assessed the VSIG4 expression in patients with MM and its prognostic impact. We analyzed 81 bone marrow and 66 extramedullary biopsy samples of MM patients using immunohistochemistry. VSIG4 mRNA expression data from the Multiple Myeloma Genomics Portal (MMGP) were analyzed to validate our results. The overall survival (OS) of the high VSIG4 expression group was significantly poorer than that of the low VSIG4 expression group (p = 0.046). VSIG4 expression was remained statistically significant after adjustment for revised international staging system (rISS) and Mayo stratification algorithm (mSMART) risk classification, respectively (p = 0.019 and 0.017). Corroborating results were also observed on analyses of VSIG4 expression in patients with extramedullary MM and external data from the MMGP. Our results suggest that VSIG4 expression in MM is an independent indicator of poor prognosis, implying a possible therapeutic target for immunotherapy for MM.

Monoclonal Antibodies in Multiple Myeloma: A New Wave of the Future

In 2015, 2 monoclonal antibodies were approved for the treatment of relapsed or refractory multiple myeloma (RRMM), elotuzumab and daratumumab. Elotuzumab is a monoclonal IgG-κ antibody directed against SLAMF7 (signaling lymphocytic activation molecule F7), a cell surface receptor involved in natural killer cell activation. Daratumumab is a monoclonal IgG-κ antibody that binds to CD38, a transmembrane protein found on the surface of myeloma cells and responsible for cellular adhesion and ectoenzymatic activity. Both elotuzumab and daratumumab act through recruitment of the immune system to enhance cellular cytotoxicity directed against myeloma cells. Elotuzumab requires lenalidomide and dexamethasone combined to enhance progression-free survival in patients with RRMM, and daratumumab has both single-agent and combination activity with either lenalidomide or the proteasome inhibitor bortezomib in RRMM. The adverse effect profile of both agents mainly consists of allergic-type infusion reactions. Other considerations for monoclonal antibody use in the treatment of MM include the potential for interference in serum protein electrophoresis testing and cross-reactivity of daratumumab with CD38 present on red blood cells. In the present report, we discussed the clinical development of daratumumab and elotuzumab and newer immunologic approaches to the treatment of MM.

Pembrolizumab, pomalidomide, and low-dose dexamethasone for relapsed/refractory multiple myeloma

Programmed death 1 (PD-1) receptor and its ligand (PD-L1) facilitate immune evasion in multiple myeloma (MM). We hypothesized that pembrolizumab, PD-1-antibody, can enhance antimyeloma cellular immunity generated by pomalidomide, leading to improved clinical responses. In this single-center, phase 2 study, 48 patients with relapsed/refractory MM (RRMM) received 28-day cycles of pembrolizumab, 200 mg IV every 2 weeks, pomalidomide 4 mg daily for 21 days, and dexamethasone 40 mg weekly. Patients had a median of 3 (range: 2-5) lines of therapy, median age 64 (range: 35-83) years, and had received both an immune modulatory drug (IMiD) and proteasome inhibitor: (35 [73%] of 48) were refractory to both; (31 [70%]) had received an autologous transplant, and (30 [62%]) had high-risk cytogenetics. Adverse events grade 3 to 4 occurred in (19 [40%] of 48 patients), including hematologic toxicities (19 [40%]), hyperglycemia (12 [25%]), and pneumonia (7 [15%]). Autoimmune events included pneumonitis (6 [13%]) and hypothyroidism (5 [10%]), mostly ≤ grade 2. Objective responses occurred in (29 [60%] of 48) patients, including stringent complete response/complete response (4 [8%]), very good partial response (9 [19%]), and partial response (16 [33%]); median duration of response was 14.7 months. At median follow-up of 15.6 months, progression-free survival (PFS) was 17.4 months and overall survival was not reached. Analyses of pretreatment marrow samples revealed a trend for increased expression of PD-L1 in responding patients and longer PFS with increased T-lymphocyte infiltrates, irrespective of PD-1 expression. Pembrolizumab, pomalidomide, and low-dose dexamethasone have acceptable safety and durable responses in RRMM patients. This trial was registered at www.clincialtrials.gov as #NCT02289222.

Immune checkpoint blockade: the role of PD-1-PD-L axis in lymphoid malignancies

The co-inhibitory receptor programmed cell death (PD)-1, expressed by immune effector cells, is credited with a protective role for normal tissue during immune responses, by limiting the extent of effector activation. Its presently known ligands, programmed death ligands (PD-Ls) 1 and 2, are expressed by a variety of cells including cancer cells, suggesting a role for these molecules as an immune evasion mechanism. Blocking of the PD-1-PD-L signaling axis has recently been shown to be effective and was clinically approved in relapsed/refractory tumors such as malignant melanoma and lung cancer, but also classical Hodgkin’s lymphoma. A plethora of trials exploring PD-1 blockade in cancer are ongoing. Here, we review the role of PD-1 signaling in lymphoid malignancies, and the latest results of trials investigating PD-1 or PD-L1 blocking agents in this group of diseases. Early phase studies proved very promising, leading to the clinical approval of a PD-1 blocking agent in Hodgkin’s lymphoma, and Phase III clinical studies are either planned or ongoing in most lymphoid malignancies.

Immune checkpoint blockade for hematologic malignancies: a review

Immune checkpoint blockade has revolutionized the treatment of cancer, with impressive responses seen in a broad variety of tumor types. Blockade of immune checkpoints and immune signaling antibodies has shown promise in multiple types of hematologic malignancies (HMs), with dramatic single agent responses for pembrolizumab and nivolumab in Hodgkin lymphoma (HL). In this review, we outline the current state of immune checkpoint blockade drug development in HMs, and discuss mechanisms of activity and resistance, and highlight potential targets in the immune tumor microenvironment (TME). Blockade of T-cell checkpoint molecules PD-1/PD-L1 and CTLA-4 are the most clinically mature of the immune checkpoint strategies. Novel and upcoming strategies for immune checkpoint blockade drug development in HMs using innovative combinations to modulate immunologic targets shows significant promise as a way to expand the number of patients with blood cancers who could benefit from immunotherapy.

New monoclonal antibodies on the horizon in multiple myeloma

Across all cancers, monoclonal antibodies have emerged as a potential strategy for cancer therapy. Monoclonal antibodies target antigens expressed on the surface of cancer cells and accessory cells. This targeted approach uses the host's immune system to promote the killing of cancer cells. Multiple myeloma (MM) is the second most common hematologic malignancy that remains incurable in the majority of patients. The treatment of MM has evolved dramatically over the past decade and continues to evolve with the approval of four new drugs in 2015. Most recently the United States Food and Drug Administration (US FDA) approved two monoclonal antibodies for the treatment of this disease. Monoclonal antibodies are generally well-tolerated and offer a novel method of action for treated relapsed and refractory disease and are now being studied in the upfront setting. In this article, we review the evidence for the existing approved monoclonal antibodies and discuss promising targeted therapies and innovative strategies for the treatment of MM.

Current treatment options of T cell-associated immunotherapy in multiple myeloma

Multiple myeloma (MM) is a complex disease and is presently an incurable malignant plasma cell tumor. Although the introduction of proteasome inhibitor and the immunomodulators markedly improved the effect of myeloma therapy, most patients still suffer from relapse even with an initially effective therapy. Accumulating evidence suggests that immunotherapy is a promising option in treating MM. And T cell plays crucial role through inducing sustained immune response in vivo in the immunotherapy of tumors. In this article, we will discuss progress of several T cell-based immunotherapies with insight into how they eradicate myeloma cells and their disadvantages.

Increase of Soluble Programmed Cell Death Ligand 1 in Patients with Chronic Hepatitis C

Objectives: To determine whether the soluble programmed cell death ligand 1 (sPD-L1) levels in patients with chronic hepatitis C (CHC) are associated with the clinical features of the disease and the efficacy of treatment, including interferon (IFN)-α. Methods: We investigated the sPD-L1 levels in the sera of 80 genotype 1b Japanese patients with CHC who underwent 12 weeks of telaprevir (TVR)- or simeprevir (SMV)-based triple therapy followed by 12 weeks of dual therapy with pegylated IFN-α plus ribavirin. Serum was also obtained from 22 patients with chronic hepatitis B (CHB) and from 10 healthy donors (HC). The sPD-L1 levels were measured using an ELISA kit. In addition, we examined the PD-L1 expression on the cell surface of immortalized hepatocytes (HPT1) after incubation with cytokines, including IFN-γ. Results: The pretreatment serum sPD-L1 levels were significantly increased in patients with CHC (median 109.3 pg/ml, range 23.1-402.3) compared with patients with CHB (69.2 pg/ml, 15.5-144.8; P <0.001) and HC (100.3 pg/ml, 40.1-166.6; P = 0.039). No significant differences in the sustained virological response (SVR) rates were found between the TVR- (85.0%, n=40) and SMV-treated (80.0%, n=40) groups, and the pretreatment levels of serum sPD-L1 were not significantly different between patients who achieved SVR (105.0 pg/ml, 23.1-402.3) and non-SVR patients (133.5 pg/ml, 39.9-187.2; P = 0.391). The pretreatment level of sPD-L1 was positively correlated with the alanine aminotransferase and alpha-fetoprotein levels (R² = 0.082, P = 0.016, and R² = 0.149, P = 0.002, respectively). Although immortalized hepatocytes do not express PD-L1, we confirmed that PD-L1 expression was induced after stimulation with IFN-γ. Conclusions: In this study, we first found that sPD-L1 was increased in patients with CHC. Our results indicate that the level of serum sPD-L1 might be associated with the progression of CHC and the generation of hepatocellular carcinoma.

PD-1/PD-L1 inhibitors in multiple myeloma: The present and the future

The introduction of PD-1/PD-L1 pathway inhibitors has marked a significant milestone in the treatment of various types of solid tumors. The current situation in multiple myeloma (MM) is rather unclear, as distinct research groups have reported discordant results. This discrepancy dominantly concerns the expression of PD-1/PD-L1 molecules as well as the identification of the responsible immune effector cell population. The results of monotherapy with PD-1/PD-L1 inhibitors have been unsatisfactory in MM, suggesting that a combination approach is needed. The most logical partners are immunomodulatory agents as they possess many synergistic effects. We are also proposing other rational and promising combinations (e.g., daratumumab, ibrutinib, anti-CD137) that warrant further investigation.