Delivering co-stimulatory tumor necrosis factor receptor agonism for cancer immunotherapy: past, current and future perspectives

Beyond Canonical Immune Checkpoints: Overexpression of TNFRSF Members 4-1BB and OX-40 Marks T Cells Exhibiting Phenotypic Features of Exhaustion in Cervical Carcinoma

T cells are pivotal in combating cancer; however, they can become exhausted during tumour progression, losing their cytotoxic capacity and upregulating inhibitory receptors including PD-1 and TIGIT. While checkpoint blockade has emerged as a potent treatment option for numerous cancers, patient selection, long-term efficacy, and adverse effects still remain an issue. For these reasons, it is important to investigate other pathways that might lead to selective reactivation of the immune system. Co-stimulatory TNFRSF receptors, including 4-1BB and OX-40, have emerged as promising targets for reactivating exhausted T cells. However, their expression on exhausted peripheral and tumour-infiltrating lymphocytes (TILs) is not well characterised, particularly in cervical cancer (CC), which remains the leading cause of gynaecological cancer mortality in low- and middle-income countries. To investigate the expression of these receptors, PBMCs were collected from CC patients and healthy donors, along with TILs from tumour biopsies, and analysed using multiparametric flow cytometry. Our findings revealed an increased population of phenotypically exhausted (PD-1+TIGIT+) CD4+ and CD8+ T cells in TILs, and, to a lesser extent, in peripheral blood and from CC patients. These exhausted T cell subsets exhibited selective overexpression of 4-1BB and OX-40 compared to phenotypically non-exhausted cells (PD-1-TIGIT-). In TILs, 4-1BB was overexpressed 12.7-fold in CD8 cells with the exhausted phenotype, OX-40 was overexpressed 3.3-fold; in CD4 cells with the exhausted phenotype, the overexpression was 7.8× and 3.8× for 4-1BB and OX-40, respectively. CD8 and CD4 T cells that were PD-1 + TIGIT+ 4-1BB+ were 7.3× and 16× more likely to be found in the tumour versus peripheral blood. Additionally, subpopulations of PD-1high T cells were significantly elevated in the tumour-infiltrating T cells and TIGIT expression was positively associated with PD-1 levels in peripheral patient CD8+ and CD4+ T cells, potentially indicating an advanced state of exhaustion. These findings suggest that TNFRSF members, especially 4-1BB, may serve as potential immunotherapeutic targets for reinvigorating exhausted T cells in CC.

First-in-human, phase 1 dose escalation study of SL-279252, a hexameric PD1-Fc-OX40L fusion protein, in patients with advanced solid tumors and lymphoma

SL-279252 is a bifunctional hexameric fusion protein adjoining the extracellular domains of PD-1 and OX40L via an inert IgG4 derived Fc domain. A Phase 1 dose escalation study was conducted in patients (pts) with advanced solid tumors or lymphomas. SL-279252 was administered intravenously across 12 dose levels (range: 0.0001-24 mg/kg). Objectives included evaluation of safety, dose-limiting toxicity (DLT), recommended phase 2 dose, pharmacokinetic and pharmacodynamic (PD) parameters, and anti-tumor activity. Forty-nine pts (48 with solid tumor and 1 with lymphoma) were enrolled (median age 64 years; 53% male; median [range] of 3 [0-5] prior systemic therapies; 61% had been previously treated with PD-1/L1 inhibitors). Most common treatment-related adverse events (AEs) were infusion-related reaction (16%), maculopapular rash (10%), fatigue (6%), and neutropenia (6%). Treatment-related Grade (G) 3 AE was neutropenia (4%). There were no G4 or G5 AEs or DLTs. SL-279252 Cmax and area under the curve (AUC) increased proportionally with dose. T½ was ~ 20 h. Baseline anti-drug antibodies (ADA) were observed in 11/42 pts who had received a PD-1 inhibitor within 250 days. 7/31 pts had a persistent SL-279252 induced ADA response. PD effects consistent with OX40 engagement included dose dependent egress of CD4 + OX40 + cells and increases in Ki67 + CD4 and CD8 central and effector memory cells in the blood. Best response by iRECIST [1] in 46 response evaluable subjects was 1 iPR and 15 iSD. SL-279252 was well tolerated. PD effects consistent with OX40 activation were observed, however, efficacy was limited which may have been due to the disease characteristics, prior treatment with PD-1/L1 inhibitors, neutralization of the PD-1 domain of SL-279252 by circulating PD-1 inhibitors, limited SL-279252 penetration into tumors or other variables. Trial register number NCT03894618. Trial registration date 28-March-2019.

Novel Cyclic Peptides Inhibiting Tumor Necrosis Factor Receptor 1 Activity

This patent application pertains to macrocyclic peptides, generally represented by Formula I. These compounds exhibit selective binding to tumor necrosis factor receptor 1 (TNFR1) and hold the potential for mitigating the progression of diseases or disorders associated with TNFα/TNFR1 signaling, including autoimmune and inflammatory conditions.

Exploring miRNA therapies and gut microbiome-enhanced CAR-T cells: advancing frontiers in glioblastoma stem cell targeting

Glioblastoma multiforme (GBM) presents a formidable challenge in oncology due to its aggressive nature and resistance to conventional treatments. Recent advancements propose a novel therapeutic strategy combining microRNA-based therapies, chimeric antigen receptor-T (CAR-T) cells, and gut microbiome modulation to target GBM stem cells and transform cancer treatment. MicroRNA therapies show promise in regulating key signalling pathways implicated in GBM progression, offering the potential to disrupt GBM stem cell renewal. CAR-T cell therapy, initially successful in blood cancers, is being adapted to target GBM by genetically engineering T cells to recognise and eliminate GBM stem cell-specific antigens. Despite early successes, challenges like the immunosuppressive tumour microenvironment persist. Additionally, recent research has uncovered a link between the gut microbiome and GBM, suggesting that gut dysbiosis can influence systemic inflammation and immune responses. Novel strategies to modulate the gut microbiome are emerging, enhancing the efficacy of microRNA therapies and CAR-T cell treatments. This combined approach highlights the synergistic potential of these innovative therapies in GBM treatment, aiming to eradicate primary tumours and prevent recurrence, thereby improving patient prognosis and quality of life. Ongoing research and clinical trials are crucial to fully exploit this promising frontier in GBM therapy, offering hope to patients grappling with this devastating disease.

MD Simulation Reveals a Trimerization-Enhanced Interaction of CD137L with CD137

CD137 is a prominent costimulatory molecule of the tumor necrosis factor (TNF) receptor superfamily that activates T cells through a complex bidirectional signaling process involving CD137L. The clinical value of immunotherapies underscores the potential of CD137L/CD137 as an effective target for boosting antitumor immune responses; however, the intricate mechanisms governing these interactions have not been fully elucidated. Herein, we constructed various oligomeric states of CD137L (monomeric, dimeric, and trimeric CD137L) and explored their interactions with CD137 using molecular dynamics simulations. Our findings revealed that trimeric CD137L exhibits higher thermal stability but reduced binding affinity for CD137 compared with the dimer form, with the A'B' loop of CD137L playing a critical role in both structural stability and promoting CD137 interactions. Notably, the formation of hexameric structures enhanced the binding affinity and stability. This study provides valuable insights into the CD137L/CD137 bidirectional signaling mechanisms, which may inform the design of next-generation CD137 agonists. Ultimately, these advancements may improve cancer immunotherapy strategies, aiming to enhance therapeutic outcomes for patients through more effective and targeted therapies.

Generation and characterization of OX40-ligand fusion protein that agonizes OX40 on T-Lymphocytes

OX40, a member of the tumor necrosis factor (TNF) receptor superfamily, is expressed on the surface of activated T cells. Upon interaction with its cognate ligand, OX40L, OX40 transmits costimulatory signals to antigen-primed T cells, promoting their activation, differentiation, and survival-processes essential for the establishment of adaptive immunity. Although the OX40-OX40L interaction has been extensively studied in the context of disease treatment, developing a substitute for the naturally expressed membrane-bound OX40L, particularly a multimerized OX40L trimers, that effectively regulates OX40-driven T cell responses remains a significant challenge. In this study, we successfully engineered soluble OX40L-fusion proteins capable of robustly activating OX40 on T cells. This was achieved by incorporating functional multimerization domains into the TNF homology domain of OX40L. These OX40L proteins bound to OX40, subsequently activated NF-κB signaling, and induced cytokine production by T cells in vitro. In vivo, mice treated with one of the OX40L-fusion proteins-comprising a single-chain OX40L trimer linked to the C-terminus of the human IgG1 Fc domain, forming a dimer of trimers-exhibited significantly enhanced clonal expansion of antigen-specific CD4+ T cells during the primary phase of the immune response. A comparable antibody-fusion single-chain TNF protein incorporating 4-1BBL, CD70 (CD27L), or GITRL in place of OX40L elicited similar in vivo T cell responses. Thus, we propose that optimizing the multimerization of OX40L proteins through innovative design strategies may facilitate the development of more effective agonists for targeted immunotherapies.

Emerging druggable targets for immune checkpoint modulation in cancer immunotherapy: the iceberg lies beneath the surface

The immune system serves as a fundamental defender against the initiation and progression of cancer. Failure of the immune system augments immunosuppressive action that leading to cancer manifestation. This immunosuppressive effect causes from significant alterations in immune checkpoint expression associated with tumoral progression. The tumor microenvironment promotes immune escape mechanisms that further amplifying immunosuppressive actions. Notably, substantial targeting of immune checkpoints has been pragmatic in the advancement of cancer research. This study highlights a comprehensive review of emerging druggable targets aimed at modulating immune checkpoint co-inhibitory as well as co-stimulatory molecules in response to immune system activation. This modulation has prompted to the development of newer therapeutic insights, eventually inducing immunogenic cell death through immunomodulatory actions. The study emphasizes the role of immune checkpoints in immunogenic regulation of cancer pathogenesis and explores potential therapeutic avenues in cancer immunotherapy.Modulation of Immunosuppressive and Immunostimulatory pathways of immune checkpoints in cancer immunotherapy.

Targeting the TNF and TNFR superfamilies in autoimmune disease and cancer

The first anti-tumour necrosis factor (TNF) monoclonal antibody, infliximab (Remicade), celebrated its 25th anniversary of FDA approval in 2023. Inhibitors of TNF have since proved clinically efficacious at reducing inflammation associated with several autoimmune diseases, including rheumatoid arthritis, psoriasis and Crohn's disease. The success of TNF inhibitors raised unrealistic expectations for targeting other members of the TNF superfamily (TNFSF) of ligands and their receptors, with difficulties in part related to their more limited, variable expression and potential redundancy. However, there has been a resurgence of interest and investment, with many of these cytokines or their cognate receptors now under clinical investigation as targets for modulation of autoimmune and inflammatory diseases, as well as cancer. This Review assesses TNFSF-targeted biologics currently in clinical development for immune system-related diseases, highlighting ongoing challenges and future directions.

Targeting TNFRSF25 by agonistic antibodies and multimeric TL1A proteins co-stimulated CD8+ T cells and inhibited tumor growth

BACKGROUND

Tumor necrosis factor receptor superfamily 25 (TNFRSF25) is a T-cell co-stimulatory receptor. Expression of its ligand, TNF-like cytokine 1A (TL1A), on mouse tumor cells has been shown to promote tumor regression. This study aimed to develop TNFRSF25 agonists (both antibodies (Abs) and TL1A proteins) and to investigate their potential antitumor effects.

METHODS

Anti-mouse TNFRSF25 (mTNFRSF25) Abs and multimeric TL1A proteins were generated as TNFRSF25 agonists. Their agonism was assessed in luciferase reporter and T-cell co-stimulation assays, and their antitumor effects were evaluated in syngeneic mouse tumor models. TNFRSF25 expression within the tumor microenvironment and the effects of an anti-mTNFRSF25 agonistic Ab on tumor-infiltrating T cells were evaluated by flow cytometry. Cell depletion assays were used to identify the immune cell types that contribute to the antitumor effect of the anti-mTNFRSF25 Ab. The Fc gamma receptor (FcγR) dependence of TNFRSF25 agonists was assessed in an in vivo T-cell expansion model and a mouse tumor model using Fc variants and FcγR-deficient mice.

RESULTS

TNFRSF25 agonists exhibited antitumor effects in syngeneic mouse tumor models without causing observed side effects. We identified an anti-mTNFRSF25 agonistic Ab, 1A6-m1, which exhibited greater antitumor activity than a higher affinity anti-TNFRSF25 Ab which engages an overlapping epitope with 1A6-m1. 1A6-m1 activated CD8+ T cells and antigen-specific T cells, leading to tumor regression; it also induced long-term antitumor immune memory. Although activating TNFRSF25 by 1A6-m1 expanded splenic regulatory T (Treg) cells, it did not influence intratumoral Treg cells. Moreover, 1A6-m1's antitumor effects required the engagement of both inhibitory FcγRIIB and activating FcγRIII. Replacing 1A6-m1's CH1-hinge region with that of human IgG2 (h2) conferred enhanced antitumor effects. Finally, we also generated multimeric human and mouse TL1A fusion proteins as TNFRSF25 agonists, and they co-stimulated CD8+ T cells and reduced tumor growth, even in the absence of Fc-FcγR interactions.

CONCLUSION

Our data demonstrates the potential of activating TNFRSF25 by Abs and multimeric TL1A proteins for cancer immunotherapy and provides insights into their development astherapeutics.

Fcγ-Receptor-Independent Controlled Activation of CD40 Canonical Signaling by Novel Therapeutic Antibodies for Cancer Therapy

The activation of CD40-mediated signaling in antigen-presenting cells is a promising therapeutic strategy to promote immune responses against tumors. Most agonistic anti-CD40 antibodies currently in development require the Fcγ-receptor (FcγR)-mediated crosslinking of CD40 molecules for a meaningful activation of CD40 signaling but have limitations due to dose-limiting toxicities. Here we describe the identification of CD40 antibodies which strongly stimulate antigen-presenting cells in an entirely FcγR-independent manner. These Fc-silenced anti-CD40 antibodies induce an efficient upregulation of costimulatory receptors and cytokine release by dendritic cells. Finally, the most active identified anti-CD40 antibody shows activity in humanized mice. More importantly, there are no signs of obvious toxicities. These studies thus demonstrate the potent activation of antigen-presenting cells with anti-CD40 antibodies lacking FcγR-binding activity and open the possibility for an efficacious and safe combination therapy for cancer patients.

Antibody agonists trigger immune receptor signaling through local exclusion of receptor-type protein tyrosine phosphatases

Antibodies can block immune receptor engagement or trigger the receptor machinery to initiate signaling. We hypothesized that antibody agonists trigger signaling by sterically excluding large receptor-type protein tyrosine phosphatases (RPTPs) such as CD45 from sites of receptor engagement. An agonist targeting the costimulatory receptor CD28 produced signals that depended on antibody immobilization and were sensitive to the sizes of the receptor, the RPTPs, and the antibody itself. Although both the agonist and a non-agonistic anti-CD28 antibody locally excluded CD45, the agonistic antibody was more effective. An anti-PD-1 antibody that bound membrane proximally excluded CD45, triggered Src homology 2 domain-containing phosphatase 2 recruitment, and suppressed systemic lupus erythematosus and delayed-type hypersensitivity in experimental models. Paradoxically, nivolumab and pembrolizumab, anti-PD-1-blocking antibodies used clinically, also excluded CD45 and were agonistic in certain settings. Reducing these agonistic effects using antibody engineering improved PD-1 blockade. These findings establish a framework for developing new and improved therapies for autoimmunity and cancer.

GITR and TIGIT immunotherapy provokes divergent multicellular responses in the tumor microenvironment of gastrointestinal cancers

BACKGROUND

Understanding the mechanistic effects of novel immunotherapy agents is critical to improving their successful clinical translation. These effects need to be studied in preclinical models that maintain the heterogenous tumor microenvironment (TME) and dysfunctional cell states found in a patient's tumor. We investigated immunotherapy perturbations targeting co-stimulatory molecule GITR and co-inhibitory immune checkpoint TIGIT in a patient-derived ex vivo system that maintains the TME in its near-native state. Leveraging single-cell genomics, we identified cell type-specific transcriptional reprogramming in response to immunotherapy perturbations.

METHODS

We generated ex vivo tumor slice cultures from fresh surgical resections of gastric and colon cancer and treated them with GITR agonist or TIGIT antagonist antibodies. We applied paired single-cell RNA and TCR sequencing to the original surgical resections, control, and treated ex vivo tumor slice cultures. We additionally confirmed target expression using multiplex immunofluorescence and validated our findings with RNA in situ hybridization.

RESULTS

We confirmed that tumor slice cultures maintained the cell types, transcriptional cell states and proportions of the original surgical resection. The GITR agonist was limited to increasing effector gene expression only in cytotoxic CD8 T cells. Dysfunctional exhausted CD8 T cells did not respond to GITR agonist. In contrast, the TIGIT antagonist increased TCR signaling and activated both cytotoxic and dysfunctional CD8 T cells. This included cells corresponding to TCR clonotypes with features indicative of potential tumor antigen reactivity. The TIGIT antagonist also activated T follicular helper-like cells and dendritic cells, and reduced markers of immunosuppression in regulatory T cells.

CONCLUSIONS

We identified novel cellular mechanisms of action of GITR and TIGIT immunotherapy in the patients' TME. Unlike the GITR agonist that generated a limited transcriptional response, TIGIT antagonist orchestrated a multicellular response involving CD8 T cells, T follicular helper-like cells, dendritic cells, and regulatory T cells. Our experimental strategy combining single-cell genomics with preclinical models can successfully identify mechanisms of action of novel immunotherapy agents. Understanding the cellular and transcriptional mechanisms of response or resistance will aid in prioritization of targets and their clinical translation.

Reconciling intrinsic properties of activating TNF receptors by native ligands versus synthetic agonists

The extracellular domain of tumor necrosis factor receptors (TNFR) generally require assembly into a homotrimeric quaternary structure as a prerequisite for initiation of signaling via the cytoplasmic domains. TNF receptor homotrimers are natively activated by similarly homo-trimerized TNF ligands, but can also be activated by synthetic agonists including engineered antibodies and Fc-ligand fusion proteins. A large body of literature from pre-clinical models supports the hypothesis that synthetic agonists targeting a diverse range of TNF receptors (including 4-1BB, CD40, OX40, GITR, DR5, TNFRSF25, HVEM, LTβR, CD27, and CD30) could amplify immune responses to provide clinical benefit in patients with infectious diseases or cancer. Unfortunately, however, the pre-clinical attributes of synthetic TNF receptor agonists have not translated well in human clinical studies, and have instead raised fundamental questions regarding the intrinsic biology of TNF receptors. Clinical observations of bell-shaped dose response curves have led some to hypothesize that TNF receptor overstimulation is possible and can lead to anergy and/or activation induced cell death of target cells. Safety issues including liver toxicity and cytokine release syndrome have also been observed in humans, raising questions as to whether those toxicities are driven by overstimulation of the targeted TNF receptor, a non-TNF receptor related attribute of the synthetic agonist, or both. Together, these clinical findings have limited the development of many TNF receptor agonists, and may have prevented generation of clinical data which reflects the full potential of TNF receptor agonism. A number of recent studies have provided structural insights into how different TNF receptor agonists bind and cluster TNF receptors, and these insights aid in deconvoluting the intrinsic biology of TNF receptors with the mechanistic underpinnings of synthetic TNF receptor agonist therapeutics.

The benefits of clustering in TNF receptor superfamily signaling

The tumor necrosis factor (TNF) receptor superfamily is a structurally and functionally related group of cell surface receptors that play crucial roles in various cellular processes, including apoptosis, cell survival, and immune regulation. This review paper synthesizes key findings from recent studies, highlighting the importance of clustering in TNF receptor superfamily signaling. We discuss the underlying molecular mechanisms of signaling, the functional consequences of receptor clustering, and potential therapeutic implications of targeting surface structures of receptor complexes.