Immunotherapy targeting 4-1BB and its ligand

Multi-niche human bone marrow on-a-chip for studying the interactions of adoptive CAR-T cell therapies with multiple myeloma

Multiple myeloma (MM), a cancer of bone marrow plasma cells, is the second-most common hematological malignancy. However, despite immunotherapies like chimeric antigen receptor (CAR)-T cells, relapse is nearly universal. The bone marrow (BM) microenvironment influences how MM cells survive, proliferate, and resist treatment. Yet, it is unclear which BM niches give rise to MM pathophysiology. Here, we present a 3D microvascularized culture system, which models the endosteal and perivascular bone marrow niches, allowing us to study MM-stroma interactions in the BM niche and model responses to therapeutic CAR-T cells. We demonstrated the prolonged survival of cell line-based and patient-derived multiple myeloma cells within our in vitro system and successfully perfused in donor-matched CAR-T cells. We then measured T cell survival, differentiation, and cytotoxicity against MM cells using a variety of analysis techniques. Our MM-on-a-chip system could elucidate the role of the BM microenvironment in MM survival and therapeutic evasion and inform the rational design of next-generation therapeutics.

Multi-Niche Human Bone Marrow On-A-Chip for Studying the Interactions of Adoptive CAR-T Cell Therapies with Multiple Myeloma

Multiple myeloma (MM), a cancer of bone marrow plasma cells, is the second-most common hematological malignancy. However, despite immunotherapies like chimeric antigen receptor (CAR)-T cells, relapse is nearly universal. The bone marrow (BM) microenvironment influences how MM cells survive, proliferate, and resist treatment. Yet, it is unclear which BM niches give rise to MM pathophysiology. Here, we present a 3D microvascularized culture system, which models the endosteal and perivascular bone marrow niches, allowing us to study MM-stroma interactions in the BM niche and model responses to therapeutic CAR-T cells. We demonstrated the prolonged survival of cell line-based and patient-derived multiple myeloma cells within our in vitro system and successfully flowed in donor-matched CAR-T cells. We then measured T cell survival, differentiation, and cytotoxicity against MM cells using a variety of analysis techniques. Our MM-on-a-chip system could elucidate the role of the BM microenvironment in MM survival and therapeutic evasion and inform the rational design of next-generation therapeutics.

TEASER

A multiple myeloma model can study why the disease is still challenging to treat despite options that work well in other cancers.

Agonism of 4-1BB for immune therapy: a perspective on possibilities and complications

Costimulatory receptors on immune cells represent attractive targets for immunotherapy given that these molecules can increase the frequency of individual protective immune cell populations and their longevity, as well as enhance various effector functions. 4-1BB, a member of the TNF receptor superfamily, also known as CD137 and TNFRSF9, is one such molecule that is inducible on several cell types, including T cells and NK cells. Preclinical studies in animal models have validated the notion that stimulating 4-1BB with agonist reagents or its natural ligand could be useful to augment conventional T cell and NK cell immunity to protect against tumor growth and against viral infection. Additionally, stimulating 4-1BB can enhance regulatory T cell function and might be useful in the right context for suppressing autoimmunity. Two human agonist antibodies to 4-1BB have been produced and tested in clinical trials for cancer, with variable results, leading to the production of a wealth of second-generation antibody constructs, including bi- and multi-specifics, with the hope of optimizing activity and selectivity. Here, we review the progress to date in agonism of 4-1BB, discuss the complications in targeting the immune system appropriately to elicit the desired activity, together with challenges in engineering agonists, and highlight the untapped potential of manipulating this molecule in infectious disease and autoimmunity.

Functions of Immune Checkpoint Molecules Beyond Immune Evasion

Immune checkpoint molecules, including inhibitory and stimulatory immune checkpoint molecules, are defined as ligand-receptor pairs that exert inhibitory or stimulatory effects on immune responses. Most of the immune checkpoint molecules that have been described so far are expressed on cells of the adaptive immune system, particularly on T cells, and of the innate immune system. They are crucial for maintaining the self-tolerance and modulating the length and magnitude of immune responses of effectors in different tissues to minimize the tissue damage. More and more evidences have shown that inhibitory or stimulatory immune checkpoint molecules are expressed on a sizeable fraction of tumor types. Although the main function of tumor cell-associated immune checkpoint molecules is considered to mediate the immune evasion, it has been reported that the immune checkpoint molecules expressed on tumor cells also play important roles in the maintenance of many malignant behaviors, including self-renewal, epithelial-mesenchymal transition, metastasis, drug resistance, anti-apoptosis, angiogenesis, or enhanced energy metabolisms. In this section, we mainly focus on delineating the roles of the tumor cell-associated immune checkpoint molecules beyond immune evasion, such as PD-L1, PD-1, B7-H3, B7-H4, LILRB1, LILRB2, TIM3, CD47, CD137, and CD70.

An Update on Anti-CD137 Antibodies in Immunotherapies for Cancer

The selective expression of CD137 on cells of the immune system (e.g., T and DC cells) and oncogenic cells in several types of cancer leads this molecule to be an attractive target to discover cancer immunotherapy. Therefore, specific antibodies against CD137 are being studied and developed aiming to activate and enhance anti-cancer immune responses as well as suppress oncogenic cells. Accumulating evidence suggests that anti-CD137 antibodies can be used separately to prevent tumor in some cases, while in other cases, these antibodies need to be co-administered with other antibodies or drugs/vaccines/regents for a better performance. Thus, in this work, we aim to update and discuss current knowledge about anti-cancer effects of anti-CD137 antibodies as mono- and combined-immunotherapies.

Analysis of the protein-protein interaction networks of differentially expressed genes in pulmonary embolism

The aim of the present study was to explore the function and interaction of differentially expressed genes (DEGs) in pulmonary embolism (PE). The gene expression profile GSE13535, was downloaded from the Gene Expression Omnibus database. The DEGs 2 and 18 h post-PE initiation were identified using the affy package in R software. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of the DEGs were analyzed using Database for Annotation Visualization and Integrated Discovery (DAVID) online analytical tools. In addition, protein-protein interaction (PPI) networks of the DEGs were constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins. The PPI network at 18 h was modularized using ClusterONE, and a functional enrichment analysis of the DEGs in the top three modules was performed with DAVID. Overall, 80 and 346 DEGs were identified 2 and 18 h after PE initiation, respectively. The KEGG pathways, including chemokine signaling and toll-like receptor signaling, were shown to be significantly enriched. The five highest degree nodes in the PPI networks at 2 or 18 h were screened. The module analysis of the PPI network at 18 h revealed 11 hub nodes. A Gene Ontology terms analysis demonstrated that the DEGs in the top three modules were associated with the inflammatory, defense and immune responses. The results of the present study suggest that the DEGs identified, including chemokine-related genes TFPI2 and TNF, may be potential target genes for the treatment of PE. The chemokine signaling pathway, inflammatory response and immune response were explored, and it may be suggested that these pathways have important roles in PE.

Targeting costimulatory molecules to improve antitumor immunity

The full activation of T cells necessitates the concomitant activation of two signals, the engagement of T-cell receptor by peptide/major histocompatibility complex II and an additional signal delivered by costimulatory molecules. The best characterized costimulatory molecules belong to B7/CD28 and TNF/TNFR families and play crucial roles in the modulation of immune response and improvement of antitumor immunity. Unfortunately, tumors often generate an immunosuppressive microenvironment, where T-cell response is attenuated by the lack of costimulatory molecules on the surface of cancer cells. Thus, targeting costimulatory pathways represent an attractive therapeutic strategy to enhance the antitumor immunity in several human cancers. Here, latest therapeutic approaches targeting costimulatory molecules will be described.

4-1BB triggering ameliorates experimental autoimmune encephalomyelitis by modulating the balance between Th17 and regulatory T cells

Agonistic anti-4-1BB Ab is known to ameliorate experimental autoimmune encephalomyelitis. 4-1BB triggering typically leads to the expansion of CD8(+) T cells, which produce abundant IFN-γ, and this in turn results in IDO-dependent suppression of autoimmune responses. However, because neutralization of IFN-γ or depletion of CD8(+) T cell only partially abrogates the effect of 4-1BB triggering, we sought to identify an additional mechanism of 4-1BB-triggered suppression of autoimmune responses using IFN-γ- or IFN-γR-deficient mice. 4-1BB triggering inhibited the generation of Th17 cells that is responsible for experimental autoimmune encephalomyelitis induction and progression, and increased Foxp3(+)CD4(+) regulatory T (Treg) cells, particularly among CD4(+) T cells. This was not due to a direct effect of 4-1BB signaling on CD4(+) T cell differentiation: 4-1BB signaling not only reduced Th17 cells and increased Treg cells in wild-type mice, which could be due to IFN-γ production by the CD8(+) T cells, but also did so in IFN-γ-deficient mice, in that case by downregulating IL-6 production. These results show that although secondary suppressive mechanisms evoked by 4-1BB triggering are usually masked by the strong effects of IFN-γ, 4-1BB signaling seems to modulate autoimmune responses by a number of mechanisms, and modulation of the Th17 versus Treg cell balance is one of those mechanisms.

The role of TNF superfamily members in T-cell function and diseases

Interactions that occur between several tumour necrosis factor (TNF)-TNF receptors that are expressed by T cells and various other immune and non-immune cell types are central to T-cell function. In this Review, I discuss the biology of four different ligand-receptor interactions - OX40 ligand and OX40, 4-1BB ligand and 4-1BB, CD70 and CD27, and TL1A and death receptor 3 - and their potential to be exploited for therapeutic benefit. Manipulating these interactions can be effective for treating diseases in which T cells have an important role, including inflammatory conditions, autoimmunity and cancer. Here, I explore how blocking or inducing the signalling pathways that are triggered by these different interactions can be an effective way to modulate immune responses.

IFN-gamma-indoleamine-2,3 dioxygenase acts as a major suppressive factor in 4-1BB-mediated immune suppression in vivo

It has been reported that 4-1BB triggering in vivo selectively suppressed the recall response of staphylococcal enterotoxin A (SEA)-specific CD4(+) T cells, in which CD8(+) T-derived TGF-beta was involved. Here, we have examined an alternative mechanism for the 4-1BB-mediated CD4(+) T suppression, as the neutralization of TGF-beta is only effective in rescuing the SEA-specific recall response at high cellular concentrations. We show that this selective suppression of CD4(+) T cells by 4-1BB triggering in vivo is mediated mainly by induction of indoleamine 2,3-dioxygenase (IDO) in an IFN-gamma-dependent manner. SEA-specific CD4(+) T responses were suppressed partly by TGF-beta-expressing CD8(+) T cells, particularly CD11c(+)CD8(+) T cells, but strongly inhibited by dendritic cells (DCs) expressing IDO. IFN-gamma that increased IDO in DCs was produced primarily from CD11c(+)CD8(+) T cells, which were expanded selectively by 4-1BB stimulation. CD4(+), CD8(+), and plasmacytoid DCs exerted a similar suppressive activity toward the SEA-specific CD4(+) T cells. Neutralization of IFN-gamma or IDO activity in vivo largely reversed the 4-1BB-mediated CD4(+) T suppression. Collectively, these data indicate that 4-1BB-dependent suppression of SEA-specific CD4(+) T responses was mediated mainly by IFN-gamma-dependent IDO induction and partially by TGF-beta.

Mechanisms involved in synergistic anticancer effects of anti-4-1BB and cyclophosphamide therapy

Chemotherapy can precondition for immunotherapy by creating an environment for homeostatic lymphoproliferation and eliminating some of the suppressive immune networks. We found that combination therapy with anti-4-1BB and cyclophosphamide (CTX) produced synergistic anticancer effects in the poorly immunogenic B16 melanoma model in mice. The antitumor effect of the combination therapy depended mainly on CD8(+) T cells, the 4-1BB-dependent expansion and differentiation of which into IFN-gamma-producing CD11c(+)CD8(+) T cells was enhanced by CTX. Anti-4-1BB induced a rapid repopulation of T and B cells from CTX-mediated lymphopenia. Anti-4-1BB protected naïve T cells from CTX and promoted proliferation of memory/effector and memory T cells. The combination treatment produced approximately 60- and 2.2-fold more CTLs per tumor-associated antigen compared with CTX or anti-4-1BB alone, respectively. This indicates that anti-4-1BB promoted a preferential expansion of tumor-specific CD8(+) T cells among the repopulated lymphocytes following CTX-mediated lymphopenia. CTX treatment enhanced 4-1BB expression on CD4 and CD8 T cells, and CTX alone or in combination with anti-4-1BB effectively suppressed peripheral regulatory T cells. Our results indicate that anti-4-1BB and CTX can be practical partners in cancer therapy because CTX creates an environment in which anti-4-1BB actively promotes the differentiation and expansion of tumor-specific CTLs.

Immune regulation and control of regulatory T cells by OX40 and 4-1BB

The TNFR family members OX40 (CD134) and 4-1BB (CD137) have been found to play major roles as costimulatory receptors for both CD4 and CD8 T cells. In particular, in many situations, they can control proliferation, survival, and cytokine production, and hence are thought to dictate accumulation of protective T cells during anti-viral and anti-tumor responses and pathogenic T cells during autoimmune reactions. As opposed to simply controlling the activity of naïve, effector, and memory T cells, recent data have suggested that both molecules are also instrumental in controlling the generation and activity of so-called regulatory or suppressor T cells (Treg), perhaps in both positive and negative manners. Part of the action on Treg might function to further promote protective or pathogenic T cells, but alternate activities of OX40 and 4-1BB on Treg are also being described that suggest that there might be control by these molecules at multiple levels that will alter the biological outcome when these receptors are ligated. This review specifically focuses on recent studies of regulatory T cells, and regulatory or suppressive activity, that are modulated by OX40 or 4-1BB.

Enhancement of the anti-leukemic activity of cytokine induced killer cells with an anti-CD19 chimeric receptor delivering a 4-1BB-ζ activating signal

OBJECTIVE

There is growing interest in the use of cytokine-induced killer (CIK) cells in cancer therapy. In this study, we sought to maximize the antileukemic activity of anti-CD19 receptor-modified CIK cells against B-lineage acute lymphoblastic leukemia (ALL).

MATERIALS AND METHODS

CIK cells were transduced with retroviral vectors carrying different types of anti-CD19 chimeric receptors: anti-CD19-zeta, anti-CD19-DAP10, anti-CD19-4-1BB-zeta, and anti-CD19-CD28-zeta. A truncated form of the receptor was used as a control. Transduced CIK cells were then analyzed for their cytotoxic activity against ALL cells and for their capability to proliferate and to release cytokines after ALL encounter.

RESULTS

CIK cells were efficiently transduced with all the anti-CD19 retroviral vectors. Anti-CD19 receptor expression conferred powerful killing activity against ALL cells. However, there were clear advantages when receptors containing the co-stimulatory molecules 4-1BB or CD28 were transduced. Such cells had significantly more potent cytotoxicity than cells expressing the anti-CD19-zeta or anti-CD19-DAP10. Moreover, the presence of 4-1BB or CD28 in the receptor increased the production of interleukin (IL)-2, tumor necrosis factor (TNF)-alpha, TNF-beta, IL-5, IL-6, and IL-8 elicited by coculture with ALL cells. Notably, anti-CD19-4-1BB-zeta CIK cells secreted particularly low levels of interleukin-10 and proliferated strongly after contact with ALL cells.

CONCLUSIONS

Anti-CD19 chimeric receptors delivering primary and costimulatory signals render CIK cells powerfully cytotoxic against ALL cells and induce secretion of immunostimulatory cytokines and proliferation. These results support the testing of genetically modified CIK cells in clinical trials.

CTLA-4 blockade during dendritic cell based booster vaccination influences dendritic cell survival and CTL expansion

Dendritic cells (DCs) are potent antigen-presenting cells and critical for the priming of CD8+ T cells. Therefore the use of these cells as adjuvant cells has been tested in a large number of experimental and clinical vaccination studies, in particular cancer vaccine studies. A number of protocols are emerging that combine vaccination with CTL expanding strategies, such as e.g. blockade of CTLA-4 signalling. On the other hand, the lifespan and in vivo survival of therapeutic DCs have only been addressed in a few studies, although this is of importance for the kinetics of CTL induction during vaccination. We have previously reported that DCs loaded with specific antigens are eliminated by antigen specific CTLs in vivo and that this elimination affects the potential for in vivo CTL generation. We now show that CTLA-4 blockade increases the number of DC vaccine induced LCMV gp33 specific CTLs and the lysis of relevant in vivo targets. However, the CTLA-4 blockage dependent expansion of CTLs also affect DC survival during booster DC injections and our data suggest that during a booster DC vaccine, the largest increase in CTL levels is already obtained during the first vaccination.

Co-immunisation with DNA encoding RANK/RANKL or 4-1BBL costimulatory molecules does not enhance effector or memory CTL responses afforded by immunisation with a tumour antigen-encoding DNA vaccine

T cell mediated immune responses are induced following interaction of MHC-presented epitope on professional antigen presenting cells such as dendritic cells (DCs) with cognate T cell receptor. Up-regulation of receptor-ligand pairs of costimulatory molecules linking DC to T cell enhances the resulting T cell responses. This 'second signalling' occurs through the B7 molecules CD80/86 expressed by DCs, and importantly through members of the TNF ligand/TNF receptor superfamilies. We have previously shown that co-expression of RANK/RANKL or 41BB-L in addition to tumour antigen in dendritic cells augmented cognate effector and memory tumour antigen-directed cytotoxic T cell responses when the DCs were used to immunise mice. Here, we examined whether co-immunisation with naked plasmid DNAs encoding antigen and these costimulatory molecule(s), would enhance antigen specific T cell responses. We demonstrate that co-immunisation with DNAs encoding tumour antigen and costimulatory molecules failed to enhance antigen-directed CTL responses, or tumour protection, afforded by immunisation with DNA encoding tumour antigen alone.

Recent Advances and Current Challenges in Tumor Immunology and Immunotherapy

Despite advances in animal studies, where the cure of the majority of mice with pre-established (albeit early-stage) tumors has become almost standard, human clinical trials have been much less successful. Here we describe some of the most recent advances in the specialist field of tumor immunology and immunotherapy, highlighting salient work to identify key problem areas and potential solutions. We make particular note of recent developments in adoptive therapy; whole-cell, DNA, and peptide vaccines; and antibody therapy. We also describe the revival of interest in regulatory T cells and conclude by detailing the need for clinical trial read-out autonomy and methods to predict which patients will respond to a particular treatment.

Dual immunoregulatory pathways of 4-1BB signaling

It is perhaps rare to encounter among the various immunologically competent receptor-ligand pairs that a single cell surface determinant unleashes both a hidden suppressive function and costimulation. 4-1BB, an activation-induced tumor necrosis factor receptor family member chiefly viewed as a powerful T-cell costimulatory molecule, is one such example. Accumulated evidence in recent years uncovered an unknown facet of in vivo 4-1BB signaling (i.e., "active suppression"). Although in vitro signaling via 4-1BB is shown to support both CD4(+) and CD8(+) T-cell responses, the same induces a predominant CD8(+) T-cell response suppressing CD4(+) T-cell function when applied in vivo. How, when, and why such dual immunoregulatory effect of anti-4-1BB monoclonal antibody (MAB) comes into play is currently the focus of intense research. Existing data, although not complete, uncover several important aspects of in vivo 4-1BB signaling in the amelioration or exacerbation of various immune disorders. Despite minor disagreements, a majority agree that upregulation of interferon (IFN)-gamma is critical to anti-4-1BB MAB therapy in addition to immune modulators such as interleukin 2, transforming growth factor beta, and indolamine 2,3-dioxygenase(5), all of which contribute greatly to the success of anti-4-1BB MAB-based immunotherapy. Anti-4-1BB MAB-mediated expansion of novel CD11c(+)CD8(+) T cells is additional weaponry that appears critical for its in vivo suppressive function. These CD11c(+)CD8(+) T cells express high levels of IFN-gamma, become effective killers, and mediate selective suppression of CD4(+) T cells. In this review, we discuss the dual nature (costimulatory and suppressive) of 4-1BB-mediated immune regulation, its current status, future direction, and its impact on the immune system, with special reference to its immunotherapy.