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.

Novel anti-B-cell maturation antigen antibody-drug conjugate (GSK2857916) selectively induces killing of multiple myeloma.

B-cell maturation antigen (BCMA), highly expressed on malignant plasma cells in human multiple myeloma (MM), has not been effectively targeted with therapeutic monoclonal antibodies. We here show that BCMA is universally expressed on the MM cell surface and determine specific anti-MM activity of J6M0-mcMMAF (GSK2857916), a novel humanized and afucosylated antagonistic anti-BCMA antibody-drug conjugate via a noncleavable linker. J6M0-mcMMAF specifically blocks cell growth via G2/M arrest and induces caspase 3-dependent apoptosis in MM cells, alone and in coculture with bone marrow stromal cells or various effector cells. It strongly inhibits colony formation by MM cells while sparing surrounding BCMA-negative normal cells. J6M0-mcMMAF significantly induces effector cell-mediated lysis against allogeneic or autologous patient MM cells, with increased potency and efficacy compared with the wild-type J6M0 without Fc enhancement. The antibody-dependent cell-mediated cytotoxicity and apoptotic activity of J6M0-mcMMAF is further enhanced by lenalidomide. Importantly, J6M0-mcMMAF rapidly eliminates myeloma cells in subcutaneous and disseminated mouse models, and mice remain tumor-free up to 3.5 months. Furthermore, J6M0-mcMMAF recruits macrophages and mediates antibody-dependent cellular phagocytosis of MM cells. Together, these results demonstrate that GSK2857916 has potent and selective anti-MM activities via multiple cytotoxic mechanisms, providing a promising next-generation immunotherapeutic in this cancer.

Enhanced cross-priming of naive CD8+ T cells by dendritic cells treated by the IMiDs® immunomodulatory compounds lenalidomide and pomalidomide.

The IMiDs(®) immunomodulatory compounds lenalidomide and pomalidomide are agents with anti-inflammatory, immunomodulatory and anti-cancer activity. An excellent success rate has been shown for multiple myeloma in phase I/II clinical trials leading to Food and Drug Administration approval of lenalidomide. One mechanism by which these drugs could enhance anti-tumour immunity may be through enhanced dendritic cell (DC) function. Thalidomide, a compound structurally related to lenalidomide and pomalidomide, is known to enhance DC function, and we have investigated whether its analogues, pomalidomide and lenalidomide, also have functional effects on DCs. We used mouse bone marrow-derived DCs treated with 5 or 10 µm pomalidomide, or lenalidomide from day 1 of culture. Treatment with IMiD(®) immunomodulatory compounds increased expression of Class I (H2-Kb), CD86, and pomalidomide also increased Class II (I-Ab) expression in bone marrow-derived DCs, as measured by flow cytometry. Fluorescent bead uptake was increased by up to 45% when DCs were treated with 5 or 10 µm pomalidomide or lenalidomide compared with non-treated DCs. Antigen presentation assays using DCs primed with ovalbumin, and syngeneic T cells from transgenic OTI and OTII mice (containing MHC restricted, ovalbumin-specific, T cells) showed that both pomalidomide and lenalidomide effectively increased CD8(+) T-cell cross-priming (by up to 47%) and that pomalidomide alone was effective in increasing CD4(+) T-cell priming (by 30%). Our observations suggest that pomalidomide and lenalidomide enhance tumour antigen uptake by DCs with an increased efficacy of antigen presentation, indicating a possible use of these drugs in DC vaccine therapies.

The role of phosphatidylinositol 3-kinase-δ in the immunomodulatory effects of lenalidomide in chronic lymphocytic leukemia.

In patients with chronic lymphocytic leukemia (CLL), lenalidomide can promote humoral immune responses but also induces a distinct disease-specific toxicity of tumor flare and cytokine release. These CLL-specific events result from increased expression of costimulatory molecules on B cells. Here we demonstrate that lenalidomide activation of CLL cells depends on the phosphatidylinositol 3-kinase p110δ (PI3K-δ) pathway. Inhibition of PI3K-δ signaling by the PI3K-δ-inhibiting drug, CAL-101, or by siRNA knockdown of p110δ, abrogates CLL cell activation, costimulatory molecule expression, and vascular endothelial growth factor and basic fibroblast growth factor gene expression that is induced by lenalidomide. In addition, CAL-101 attenuates lenalidomide-mediated increases in immunoglobulin M production by normal B cells. Collectively, these data demonstrate the importance of PI3K-δ signaling for lenalidomide immune modulation. These findings may guide development of strategies for the treatment of CLL that combine lenalidomide with CAL-101, with other inhibitors of the PI3K-δ pathway, or with other agents that target downstream kinases of this signaling pathway.

Immunomodulatory effects of lenalidomide and pomalidomide on interaction of tumor and bone marrow accessory cells in multiple myeloma.

The bone marrow (BM) microenvironment consists of extracellular-matrix and the cellular compartment including immune cells. Multiple myeloma (MM) cell and BM accessory cell interaction promotes MM survival via both cell-cell contact and cytokines. Immunomodulatory agents (IMiDs) target not only MM cells, but also MM cell-immune cell interactions and cytokine signaling. Here we examined the in vitro effects of IMiDs on cytokine signaling triggered by interaction of effector cells with MM cells and BM stroma cells. IMiDs diminished interleukin-2, interferonγ, and IL-6 regulator suppressor of cytokine signaling (SOCS)1 expression in immune (CD4T, CD8T, natural-killer T, natural-killer) cells from both BM and PB of MM patients. In addition, coculture of MM cells with healthy PBMCs induced SOCS1 expression in effector cells; conversely, treatment with IMiDs down-regulated the SOCS1 expression. SOCS1 negatively regulates IL-6 signaling and is silenced by hypermethylation in MM cells. To define the mechanism of inhibitory-cytokine signaling in effector cells and MM cells, we next analyzed the interaction of immune cells with MM cells that were epigenetically modified to re-express SOCS1; IMiDs induced more potent CTL responses against SOCS1 re-expressing-MM cells than unmodified MM cells. These data therefore demonstrate that modulation of SOCS1 may enhance immune response and efficacy of IMiDs in MM.

An IMiD-induced SALL4 degron system for selective degradation of target proteins.

Regulating the amount of proteins in living cells is a powerful approach for understanding the functions of the proteins. Immunomodulatory drugs (IMiDs) induce the degradation of neosubstrates by interacting with celebron (CRBN) in the cullin E3 ubiquitin ligase complex (CRL4CRBN). Here, we developed the IMiD-dependent Sal-like protein 4 (SALL4) degron (S4D) system for chemical protein knockdown. In transient assays, an N- or C-terminal S4D tag induced the degradation of proteins localized to various subcellular compartments, including the plasma membrane. The activity of luciferase-S4D was reduced by 90% within 3 h of IMiD treatment. IMiD treatment reduced the expression of endogenous S4D-fused RelA and IκBα in knock-in (KI) experiments. Interestingly, the IκBα knockdown suggested that there may be another, unknown mechanism for RelA translocation to the nucleus. Furthermore, 5-hydroxythalidomide as a thalidomide metabolite specifically degradated S4D-tagged protein. These results indicate that the S4D system is a useful tool for cellular biology.

Lenalidomide: a new agent for patients with relapsed or refractory multiple myeloma.

Lenalidomide is a potent, novel thalidomide analog that has demonstrated promising clinical activity in patients with relapsed or refractory multiple myeloma (MM). It is a lead immunomodulatory drug currently approved by the U.S. Food and Drug Administration. Neutropenia, thrombocytopenia, and thromboembolic events are common adverse effects associated with lenalidomide therapy in patients with MM. Careful monitoring of those known serious adverse effects is essential to prevent life-threatening complications. This article discusses lenalidomide's mechanisms of action, clinical trial results, and the management of common adverse effects in patients with MM.

Clinical and Immune Effects of Lenalidomide in Combination with Gemcitabine in Patients with Advanced Pancreatic Cancer.

PURPOSE: To assess the immunomodulatory and clinical effects of lenalidomide with standard treatment of gemcitabine in patients with advanced pancreatic cancer. PATIENTS AND METHODS: Patients with advanced pancreatic cancer were treated in first line with lenalidomide orally for 21 days of a 28 days cycle and the standard regimen for gemcitabine. In Part I, which we previously have reported, the dose of lenalidomide was defined (n = 12). In Part II, every other consecutive patient was treated with either lenalidomide (Group A, n = 11) or gemcitabine (Group B, n = 10) during cycle 1. From cycle 2 on, all Part II patients received the combination. RESULTS: A significant decrease in the proliferative response of peripheral blood mononuclear cells and the frequency of DCs were noted in patients at baseline compared to healthy control donors while the frequencies of CD4+ and CD8+ T cells, NK-cells and MDSCs were significantly higher in patients compared to controls. In Group A, a significant increase in the absolute numbers of activated (HLA-DR+) CD4 and CD8 T cells and CD8 effector memory T cells (p<0.01) was noted during treatment. A statistical increment in the absolute numbers of Tregs were seen after cycle 1 (p<0.05). The addition of gemcitabine, reduced most lymphocyte subsets (p<0.05). In Group B, the proportion of lymphocytes remained unchanged during the study period. There was no difference in overall survival, progression free survival and survival rate at one year comparing the two groups. DISCUSSION: Patients with advanced pancreatic carcinoma had impaired immune functions. Lenalidomide augmented T cell reactivities, which were abrogated by gemcitabine. However, addition of lenalidomide to gemcitabine seemed to have no therapeutic impact compared to gemcitabine alone in this non-randomized study. TRIAL REGISTRATION: ClinicalTrials.gov NCT01547260.

Lenalidomide and thalidomide: mechanisms of action--similarities and differences.

Multiple myeloma is a B-cell malignancy characterized by an excess of monotypic plasma cells in the bone marrow. The molecular mechanisms that are involved in disease progression depend on the interaction between the multiple myeloma cells and the bone microenvironment. Because these mechanisms have been well characterized, it is possible to develop regimens that are more specific to pathways involved in the pathogenesis of multiple myeloma than is typical for conventional chemotherapy in disease management. Thalidomide and immunomodulatory drugs (IMiDs) have now been shown to block several pathways important for disease progression in multiple myeloma. First established as agents with antiangiogenic properties, thalidomide and IMiDs inhibit the production of interleukin (IL)-6, which is a growth factor for the proliferation of myeloma cells. In addition, they activate apoptotic pathways through caspase 8-mediated cell death. At the mitochondrial level, they are responsible for c-jun terminal kinase (JNK)-dependent release of cytochrome-c and Smac into the cytosol of cells, where they regulate the activity of molecules that affect apoptosis. By activating T cells to produce IL-2, thalidomide and IMiDs alter natural killer (NK) cell numbers and function, thus augmenting the activity of NK-dependent cytotoxicity. Data delineating these events have been derived from experiments done in resistant and sensitive multiple myeloma cell lines. Although thalidomide and IMiDs demonstrate similar biologic activities, IMiDs are more potent than thalidomide and achieve responses at lower doses. Lenalidomide, a thalidomide derivative, has also been shown to have a different toxicity profile. Our understanding of the mechanism of action of these agents has provided a platform for exciting clinical trials evaluating combinations of thalidomide and lenalidomide with both conventional chemotherapy and newer targeted agents.

Immunological effects of thalidomide and its chemical and functional analogs.

Thalidomide has recently shown considerable promise in the treatment of a number of conditions, such as leprosy and cancer. Its effectiveness in the clinic has been ascribed to wide-ranging properties, including anti-TNF-alpha, T-cell costimulatory and antiangiogenic activity. Novel compounds with improved immunomodulatory activity and side effect profiles are also being evaluated. These include selective cytokine inhibitory drugs (SelCIDs), with greatly improved TNF-alpha inhibitory activity, and immunomodulatory drugs (IMiDs) that are structural analogs of thalidomide, with improved properties. A third group recently identified within the SelCID group, with phosphodiesterase type 4-independent activity, is in the process of being characterized in laboratory studies. This review describes the emerging immunological properties of thalidomide, from a historical context to present-day clinical applications, most notably in multiple myeloma but also in other cancers, inflammatory disease, and HIV. We also describe the laboratory studies that have led to the characterization and development of SelCIDs and IMiDs into potentially clinically relevant drugs. Early trial data suggest that these novel immunomodulatory compounds may supercede thalidomide to become established therapies, particularly in certain cancers. Further evidence is required, however, to correlate the clinical efficacy of these compounds with their known immunomodulatory, antiangiogenic, and antitumor properties.

Prognostic indicators of lenalidomide for multiple myeloma: consensus and controversy.

The long-term outcome of multiple myeloma (MM) has been greatly improved through new agents, one being lenalidomide (LEN). Based upon the findings of in vitro experiments, its mode of action against MM occurs through a combination of direct tumoricidal effects on myeloma cells, modulatory effects on tumor immunity and tumor microenvironment-regulatory effects. However, it has not been clearly defined whether the clinical response and long-term outcome of MM with LEN treatment truly reflect the mechanisms of action of LEN proposed by in vitro studies. To ascertain what is known and what remains to be elucidated with LEN, we review the current literature on the mode of action of LEN in association with myeloma pathophysiology, and discuss the prognostic indicators in the treatment of MM with LEN.

Thalidomide: current and potential clinical applications.

More than three decades after its withdrawal from the world marketplace, thalidomide is attracting growing interest because of its reported immunomodulatory and anti-inflammatory properties. Current evidence indicates that thalidomide reduces the activity of the inflammatory cytokine tumor necrosis factor (TNF)-alpha by accelerating the degradation of its messenger RNA. Thalidomide also inhibits angiogenesis. Recently, the drug was approved for sale in the United States for the treatment of erythema nodosum leprosum, an inflammatory complication of Hansen's disease. However, it has long been used successfully in several other dermatologic disorders, including aphthous stomatitis, Behçet's syndrome, chronic cutaneous systemic lupus erythematosus, and graft-versus-host disease, the apparent shared characteristic of which is immune dysregulation. Many recent studies have evaluated thalidomide in patients with human immunodeficiency virus (HIV) infection; the drug is efficacious against oral aphthous ulcers, HIV-associated wasting syndrome, HIV-related diarrhea, and Kaposi's sarcoma. To prevent teratogenicity, a comprehensive program has been established to control access to the drug, including registration of prescribing physicians, dispensing pharmacies, and patients; mandatory informed consent and education procedures; and limitation of the quantity of drug dispensed. Clinical and, in some patients, electrophysiologic monitoring for peripheral neuropathy is indicated with thalidomide therapy. Other adverse effects include sedation and constipation. With appropriate safeguards, thalidomide may benefit patients with a broad variety of disorders for which existing treatments are inadequate.

Immunotherapeutic and antitumour potential of thalidomide analogues.

The immunomodulatory drug thalidomide has been shown to be clinically useful in a number of conditions including various immunological disorders and cancers. Clinical activity in vivo is attributed to the wide ranging immunological and non-immunological properties possessed by this drug; these include anti-TNF-alpha, T-cell co-stimulatory, anti-angiogenic activities and also direct antitumour activity. Recently, the design of compounds based on the thalidomide structure has led to the synthesis of analogues with greatly enhanced immunological activity and with similarly decreased toxicity. These derivatives fail into at least two categories; selective cytokine inhibitory drugs (SelCID), which are phosphodiesterase Type 4 (PDE4) inhibitors and immunomodulatory drugs (IMiD), similar to thalidomide which act via unknown mechanism(s). These compounds are in the process of being characterised in laboratory studies and are also now being assessed in Phase I and Phase I/II clinical studies. In this review we will highlight the properties of these two novel classes of compound in terms of their effects on both immunological and non-immunological systems in vitro. We will also describe how these studies are enabling the characterisation and development of these compounds into clinically relevant drugs in widely varying diseases. To this end we will describe the various clinical studies of lead compounds that are in progress and speculate as to the potential and future development of these exciting compounds.

Generating hypotheses by discovering implicit associations in the literature: a case report of a search for new potential therapeutic uses for thalidomide.

The availability of scientific bibliographies through online databases provides a rich source of information for scientists to support their research. However, the risk of this pervasive availability is that an individual researcher may fail to find relevant information that is outside the direct scope of interest. Following Swanson's ABC model of disjoint but complementary structures in the biomedical literature, we have developed a discovery support tool to systematically analyze the scientific literature in order to generate novel and plausible hypotheses. In this case report, we employ the system to find potentially new target diseases for the drug thalidomide. We find solid bibliographic evidence suggesting that thalidomide might be useful for treating acute pancreatitis, chronic hepatitis C, Helicobacter pylori-induced gastritis, and myasthenia gravis. However, experimental and clinical evaluation is needed to validate these hypotheses and to assess the trade-off between therapeutic benefits and toxicities.

Thalidomide: new indications?

Thalidomide, which was developed as a nonbarbiturate sedative agent, was taken off the market in 1961 after it was linked to a spate of major birth defects. Gradually, thalidomide was reintroduced for the treatment of a few skin diseases including leprous erythema nodosum, severe mucosal ulcers (e.g., associated with HIV infection or Behçet's disease), lymphocytic skin infiltrations, cutaneous lupus erythematosus, and chronic graft-versus-host disease. Recent reports of original pharmacological properties including modulation of cytokine production (mainly reduced TNF-alpha production) and inhibition of angiogenesis have led to the suggestion that thalidomide may be useful in some inflammatory and neoplastic conditions. Several open-label studies and case reports have described the effects of thalidomide in Crohn's disease, rheumatoid arthritis, ankylosing spondylarthritis, systemic sclerosis, and a few other systemic disorders. In these indications, minor but dose-limiting side effects were apparently common. Thalidomide analogs with better acceptability profiles are under evaluation. The anti-angiogenic effects of thalidomide may make this compound valuable as single-drug therapy or as an adjunct to chemotherapy in patients with cancer, particularly those with metastases or multiple myeloma. This possibility requires further evaluation.

Thalidomide--a therapy for the immunological consequences of HIV infection?

The beneficial effects of the teratogenic drug thalidomide on a variety of disorders involving the immune system have been established recently. Comparison of symptoms and immunologic abnormalities of such diseases with the acquired immunodeficiency syndrome, as well as experimentally obtained results suggest that thalidomide may be a useful agent suppressing autoaggressive reactions initiated by the human immunodeficiency virus.

Thalidomide-based treatment for HIV-associated multiple myeloma: a case report.

The spectrum of hematologic and immunologic abnormalities induced by HIV infection is broad. Although the incidence of HIV-associated B-cell neoplasms has increased, relatively few cases of multiple myeloma have been reported, and even fewer cases have detailed treatment outcome. The case of an HIV-infected man in whom multiple myeloma was diagnosed following progressive anemia and fatigue is described. The patient began treatment consisting of thalidomide, dexamethasone, and clarithromycin, which led to a rapid and dramatic antitumor response. He experienced modest regimen-related toxicities while retaining a normal CD4+ T-lymphocyte count and a nondetectable HIV viral load. The immunologic and antitumor effects of thalidomide in the context of multiple myeloma and HIV infection are also briefly reviewed. Given thalidomide's relatively favorable side-effect profile and purported immunologic benefit, further studies of this drug in the treatment of HIV-associated multiple myeloma should be pursued.

Thalidomide: dual benefits in palliative medicine and oncology.

Thalidomide is an immunomodulator, anti-angiogenic agent, anti-cytokine, and anti-integrin. Alone or in combination with other drugs, thalidomide has also demonstrated anti-cachexin and anti-neoplastic properties. Anorexia and cachexia are common symptoms of advanced cancer. Since certain cytokines also promote tumor growth, we may have a class of agents with palliative and anti-tumor benefits in combination with anti-neoplastics and anti-cytokines, such as thalidomide.