Safety and Clinical Activity of MEDI0562, a Humanized OX40 Agonist Monoclonal Antibody, in Adult Patients with Advanced Solid Tumors

Agonist Antibodies for Cancer Immunotherapy: History, Hopes, and Challenges

Immunotherapy is among the most promising new treatment modalities to arise over the last two decades; antibody drugs are delivering immunotherapy to millions of patients with many different types of cancer. Initial success with antibody therapeutics came in the form of direct targeting or cytotoxic antibodies, such as rituximab and trastuzumab, which bind directly to tumor cells to elicit their destruction. These were followed by immunomodulatory antibodies that elicit antitumor responses by either stimulating immune cells or relieving tumor-mediated suppression. By far the most successful approach in the clinic to date has been relieving immune suppression, with immune checkpoint blockade now a standard approach in the treatment of many cancer types. Despite equivalent and sometimes even more impressive effects in preclinical models, agonist antibodies designed to stimulate the immune system have lagged behind in their clinical translation. In this review, we document the main receptors that have been targeted by agonist antibodies, consider the various approaches that have been evaluated to date, detail what we have learned, and consider how their anticancer potential can be unlocked.

OX40/OX40 ligand and its role in precision immune oncology

Immune checkpoint inhibitors have changed the treatment landscape for various malignancies; however, their benefit is limited to a subset of patients. The immune machinery includes both mediators of suppression/immune evasion, such as PD-1, PD-L1, CTLA-4, and LAG-3, all of which can be inhibited by specific antibodies, and immune-stimulatory molecules, such as T-cell co-stimulatory receptors that belong to the tumor necrosis factor receptor superfamily (TNFRSF), including OX40 receptor (CD134; TNFRSF4), 4-1BB (CD137; TNFRSF9), and glucocorticoid-induced TNFR-related (GITR) protein (CD357; TNFRSF18). In particular, OX40 and its binding ligand OX40L (CD134L; TNFSF4; CD252) are critical for immunoregulation. When OX40 on activated T cells binds OX40L on antigen-presenting cells, T-cell activation and immune stimulation are initiated via enhanced T-cell survival, proliferation and cytotoxicity, memory T-cell formation, and abrogation of regulatory T cell (Treg) immunosuppressive functions. OX40 agonists are in clinical trials both as monotherapy and in combination with other immunotherapy agents, in particular specific checkpoint inhibitors, for cancer treatment. To date, however, only a minority of patients respond. Transcriptomic profiling reveals that OX40 and OX40L expression vary between and within tumor types, and that only ~ 17% of cancer patients have high OX40 and low OX40L, one of the expression patterns that might be theoretically amenable to OX40 agonist enhancement. Taken together, the data suggest that the OX40/OX40L machinery is a critical part of the immune stimulatory system and that understanding endogenous expression patterns of these molecules and co-existing checkpoints merits further investigation in the context of a precision immunotherapy strategy for cancer therapy.

Fcγ receptors and immunomodulatory antibodies in cancer

The discovery of both cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and programmed cell death protein 1 (PD1) as negative regulators of antitumour immunity led to the development of numerous immunomodulatory antibodies as cancer treatments. Preclinical studies have demonstrated that the efficacy of immunoglobulin G (IgG)-based therapies depends not only on their ability to block or engage their targets but also on the antibody's constant region (Fc) and its interactions with Fcγ receptors (FcγRs). Fc-FcγR interactions are essential for the activity of tumour-targeting antibodies, such as rituximab, trastuzumab and cetuximab, where the killing of tumour cells occurs at least in part due to these mechanisms. However, our understanding of these interactions in the context of immunomodulatory antibodies designed to boost antitumour immunity remains less explored. In this Review, we discuss our current understanding of the contribution of FcγRs to the in vivo activity of immunomodulatory antibodies and the challenges of translating results from preclinical models into the clinic. In addition, we review the impact of genetic variability of human FcγRs on the activity of therapeutic antibodies and how antibody engineering is being utilized to develop the next generation of cancer immunotherapies.

Acquisition of suppressive function by conventional T cells limits antitumor immunity upon Treg depletion

Regulatory T (Treg) cells contribute to immune homeostasis but suppress immune responses to cancer. Strategies to disrupt Treg cell-mediated cancer immunosuppression have been met with limited clinical success, but the underlying mechanisms for treatment failure are poorly understood. By modeling Treg cell-targeted immunotherapy in mice, we find that CD4+ Foxp3- conventional T (Tconv) cells acquire suppressive function upon depletion of Foxp3+ Treg cells, limiting therapeutic efficacy. Foxp3- Tconv cells within tumors adopt a Treg cell-like transcriptional profile upon ablation of Treg cells and acquire the ability to suppress T cell activation and proliferation ex vivo. Suppressive activity is enriched among CD4+ Tconv cells marked by expression of C-C motif receptor 8 (CCR8), which are found in mouse and human tumors. Upon Treg cell depletion, CCR8+ Tconv cells undergo systemic and intratumoral activation and expansion, and mediate IL-10-dependent suppression of antitumor immunity. Consequently, conditional deletion of Il10 within T cells augments antitumor immunity upon Treg cell depletion in mice, and antibody blockade of IL-10 signaling synergizes with Treg cell depletion to overcome treatment resistance. These findings reveal a secondary layer of immunosuppression by Tconv cells released upon therapeutic Treg cell depletion and suggest that broader consideration of suppressive function within the T cell lineage is required for development of effective Treg cell-targeted therapies.

Immune checkpoints are predominantly co-expressed by clonally expanded CD4+FoxP3+ intratumoral T-cells in primary human cancers

BACKGROUND

In addition to anti-PD(L)1, anti-CTLA-4 and anti-LAG-3, novel immune checkpoint proteins (ICP)-targeted antibodies have recently failed to demonstrate significant efficacy in clinical trials. In these trials, patients were enrolled without screening for drug target expression. Although these novel ICP-targeted antibodies were expected to stimulate anti-tumor CD8 + T-cells, the rationale for their target expression in human tumors relied on pre-clinical IHC stainings and transcriptomic data, which are poorly sensitive and specific techniques for assessing membrane protein expression on immune cell subsets. Our aim was to describe ICP expression on intratumoral T-cells from primary solid tumors to better design upcoming neoadjuvant cancer immunotherapy trials.

METHODS

We prospectively performed multiparameter flow cytometry and single-cell RNA sequencing (scRNA-Seq) paired with TCR sequencing on freshly resected human primary tumors of various histological types to precisely determine ICP expression levels within T-cell subsets.

RESULTS

Within a given tumor type, we found high inter-individual variability for tumor infiltrating CD45 + cells and for T-cells subsets. The proportions of CD8+ T-cells (~ 40%), CD4+ FoxP3- T-cells (~ 40%) and CD4+ FoxP3+ T-cells (~ 10%) were consistent across patients and indications. Intriguingly, both stimulatory (CD25, CD28, 4-1BB, ICOS, OX40) and inhibitory (PD-1, CTLA-4, PD-L1, CD39 and TIGIT) checkpoint proteins were predominantly co-expressed by intratumoral CD4+FoxP3+ T-cells. ScRNA-Seq paired with TCR sequencing revealed that T-cells with high clonality and high ICP expressions comprised over 80% of FoxP3+ cells among CD4+ T-cells. Unsupervised clustering of flow cytometry and scRNAseq data identified subsets of CD8+ T-cells and of CD4+ FoxP3- T-cells expressing certain checkpoints, though these expressions were generally lower than in CD4+ FoxP3+ T-cell subsets, both in terms of proportions among total T-cells and ICP expression levels.

CONCLUSIONS

Tumor histology alone does not reveal the complete picture of the tumor immune contexture. In clinical trials, assumptions regarding target expression should rely on more sensitive and specific techniques than conventional IHC or transcriptomics. Flow cytometry and scRNAseq accurately characterize ICP expression within immune cell subsets. Much like in hematology, flow cytometry can better describe the immune contexture of solid tumors, offering the opportunity to guide patient treatment according to drug target expression rather than tumor histological type.

Head and Neck Squamous Cell Carcinoma Vaccine: Current Landscape and Perspectives

The treatment of unresectable or metastatic Head and Neck Squamous Cell Carcinoma (HNSCC) has traditionally relied on chemotherapy or radiotherapy, yielding suboptimal outcomes. The introduction of immunotherapy has significantly improved HNSCC treatment, even if the long-term results cannot be defined as satisfactory. Its mechanism of action aims to counteract the blockade of tumor immune escape. This result can also be obtained by stimulating the immune system with vaccines. This review scope is to comprehensively gather existing evidence and summarize ongoing clinical trials focused on therapeutic vaccines for HNSCC treatment. The current landscape reveals numerous promising drugs in the early stages of experimentation, along with a multitude of trials that have been suspended or abandoned for years. Nonetheless, there are encouraging results and ongoing experiments that instill hope for potential paradigm shifts in HNSCC therapy.

Fasting mimicking diet in mice delays cancer growth and reduces immunotherapy-associated cardiovascular and systemic side effects

Immune checkpoint inhibitors cause side effects ranging from autoimmune endocrine disorders to severe cardiotoxicity. Periodic Fasting mimicking diet (FMD) cycles are emerging as promising enhancers of a wide range of cancer therapies including immunotherapy. Here, either FMD cycles alone or in combination with anti-OX40/anti-PD-L1 are much more effective than immune checkpoint inhibitors alone in delaying melanoma growth in mice. FMD cycles in combination with anti-OX40/anti-PD-L1 also show a trend for increased effects against a lung cancer model. As importantly, the cardiac fibrosis, necrosis and hypertrophy caused by immune checkpoint inhibitors are prevented/reversed by FMD treatment in both cancer models whereas immune infiltration of CD3+ and CD8+ cells in myocardial tissues and systemic and myocardial markers of oxidative stress and inflammation are reduced. These results indicate that FMD cycles in combination with immunotherapy can delay cancer growth while reducing side effects including cardiotoxicity.

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

The tumor necrosis factor superfamily (TNFSF) and their receptors (TNFRSF) are important regulators of the immune system, mediating proliferation, survival, differentiation, and function of immune cells. As a result, their targeting for immunotherapy is attractive, although to date, under-exploited. In this review we discuss the importance of co-stimulatory members of the TNFRSF in optimal immune response generation, the rationale behind targeting these receptors for immunotherapy, the success of targeting them in pre-clinical studies and the challenges in translating this success into the clinic. The efficacy and limitations of the currently available agents are discussed alongside the development of next generation immunostimulatory agents designed to overcome current issues, and capitalize on this receptor class to deliver potent, durable and safe drugs for patients.

Therapeutic Vaccination in Head and Neck Squamous Cell Carcinoma—A Review

Therapeutic vaccination is one of the most effective immunotherapeutic approaches, second only to immune checkpoint inhibitors (ICIs), which have already been approved for clinical use. Head and neck squamous cell carcinomas (HNSCCs) are heterogenous epithelial tumors of the upper aerodigestive tract, and a significant proportion of these tumors tend to exhibit unfavorable therapeutic responses to the existing treatment options. Comprehending the immunopathology of these tumors and choosing an appropriate immunotherapeutic maneuver seems to be a promising avenue for solving this problem. The current review provides a detailed overview of the strategies, targets, and candidates for therapeutic vaccination in HNSCC. The classical principle of inducing a potent, antigen-specific, cell-mediated cytotoxicity targeting a specific tumor antigen seems to be the most effective mechanism of therapeutic vaccination, particularly against the human papilloma virus positive subset of HNSCC. However, approaches such as countering the immunosuppressive tumor microenvironment of HNSCC and immune co-stimulatory mechanisms have also been explored recently, with encouraging results.

The Role of Different Immunocompetent Cell Populations in the Pathogenesis of Head and Neck Cancer-Regulatory Mechanisms of Pro- and Anti-Cancer Activity and Their Impact on Immunotherapy

Head and neck squamous cell carcinoma (HNSCC) is one of the most aggressive and heterogeneous groups of human neoplasms. HNSCC is characterized by high morbidity, accounting for 3% of all cancers, and high mortality with ~1.5% of all cancer deaths. It was the most common cancer worldwide in 2020, according to the latest GLOBOCAN data, representing the seventh most prevalent human malignancy. Despite great advances in surgical techniques and the application of modern combinations and cytotoxic therapies, HNSCC remains a leading cause of death worldwide with a low overall survival rate not exceeding 40-60% of the patient population. The most common causes of death in patients are its frequent nodal metastases and local neoplastic recurrences, as well as the relatively low response to treatment and severe drug resistance. Much evidence suggests that the tumour microenvironment (TME), tumour infiltrating lymphocytes (TILs) and circulating various subpopulations of immunocompetent cells, such regulatory T cells (CD4+CD25+Foxp3+Tregs), cytotoxic CD3+CD8+ T cells (CTLs) and CD3+CD4+ T helper type 1/2/9/17 (Th1/Th2/Th9/Th17) lymphocytes, T follicular helper cells (Tfh) and CD56dim/CD16bright activated natural killer cells (NK), carcinoma-associated fibroblasts (CAFs), myeloid-derived suppressor cells (MDSCs), tumour-associated neutrophils (N1/N2 TANs), as well as tumour-associated macrophages (M1/M2 phenotype TAMs) can affect initiation, progression and spread of HNSCC and determine the response to immunotherapy. Rapid advances in the field of immuno-oncology and the constantly growing knowledge of the immunosuppressive mechanisms and effects of tumour cancer have allowed for the use of effective and personalized immunotherapy as a first-line therapeutic procedure or an essential component of a combination therapy for primary, relapsed and metastatic HNSCC. This review presents the latest reports and molecular studies regarding the anti-tumour role of selected subpopulations of immunocompetent cells in the pathogenesis of HNSCC, including HPV+ve (HPV+) and HPV-ve (HPV-) tumours. The article focuses on the crucial regulatory mechanisms of pro- and anti-tumour activity, key genetic or epigenetic changes that favour tumour immune escape, and the strategies that the tumour employs to avoid recognition by immunocompetent cells, as well as resistance mechanisms to T and NK cell-based immunotherapy in HNSCC. The present review also provides an overview of the pre- and clinical early trials (I/II phase) and phase-III clinical trials published in this arena, which highlight the unprecedented effectiveness and limitations of immunotherapy in HNSCC, and the emerging issues facing the field of HNSCC immuno-oncology.

First-in-human phase I study of the OX40 agonist GSK3174998 with or without pembrolizumab in patients with selected advanced solid tumors (ENGAGE-1)

BACKGROUND

The phase I first-in-human study ENGAGE-1 evaluated the humanized IgG1 OX40 agonistic monoclonal antibody GSK3174998 alone (Part 1 (P1)) or in combination with pembrolizumab (Part 2 (P2)) in patients with advanced solid tumors.

METHODS

GSK3174998 (0.003-10 mg/kg) ± pembrolizumab (200 mg) was administered intravenously every 3 weeks using a continuous reassessment method for dose escalation. Primary objectives were safety and tolerability; secondary objectives included pharmacokinetics, immunogenicity, pharmacodynamics, and clinical activity.

RESULTS

138 patients were enrolled (45 (P1) and 96 (P2, including 3 crossovers)). Treatment-related adverse events occurred in 51% (P1) and 64% (P2) of patients, fatigue being the most common (11% and 24%, respectively). No dose-toxicity relationship was observed, and maximum-tolerated dose was not reached. Dose-limiting toxicities (P2) included Grade 3 (G3) pleural effusion and G1 myocarditis with G3 increased troponin. GSK3174998 ≥0.3 mg/kg demonstrated pharmacokinetic linearity and >80% receptor occupancy on circulating T cells; 0.3 mg/kg was selected for further evaluation. Limited clinical activity was observed for GSK3174998 (P1: disease control rate (DCR) ≥24 weeks 9%) and was not greater than that expected for pembrolizumab alone (P2: overall response rate 8%, DCR ≥24 weeks 28%). Multiplexed immunofluorescence data from paired biopsies suggested that increased infiltration of natural killer (NK)/natural killer T (NKT) cells and decreased regulatory T cells (Tregs) in the tumor microenvironment may contribute to clinical responses: CD16+CD56-CD134+ NK /NKT cells and CD3+CD4+FOXP3+CD134+ Tregs exhibited the largest magnitude of change on treatment, whereas CD3+CD8+granzyme B+PD-1+CD134+ cytotoxic T cells were the least variable. Tumor gene expression profiling revealed an upregulation of inflammatory responses, T-cell proliferation, and NK cell function on treatment with some inflammatory cytokines upregulated in peripheral blood. However, target engagement, evidenced by pharmacologic activity in peripheral blood and tumor tissue, did not correlate with clinical efficacy. The low number of responses precluded identifying a robust biomarker signature predictive of response.

CONCLUSIONS

GSK3174998±pembrolizumab was well tolerated over the dose range tested and demonstrated target engagement. Limited clinical activity does not support further development of GSK3174998±pembrolizumab in advanced cancers.

TRIAL REGISTRATION NUMBER

NCT02528357.

Targeting Cbl-b in cancer immunotherapy

Cancer immunotherapy with immune-checkpoint blockade has improved the outcomes of patients with various malignancies, yet a majority do not benefit or develop resistance. To address this unmet need, efforts across the field are targeting additional coinhibitory receptors, costimulatory proteins, and intracellular mediators that could prevent or bypass anti-PD1 resistance mechanisms. The CD28 costimulatory pathway is necessary for antigen-specific T cell activation, though prior CD28 agonists did not translate successfully to clinic due to toxicity. Casitas B lymphoma-b (Cbl-b) is a downstream, master regulator of both CD28 and CTLA-4 signaling. This E3 ubiquitin ligase regulates both innate and adaptive immune cells, ultimately promoting an immunosuppressive tumor microenvironment (TME) in the absence of CD28 costimulation. Recent advances in pharmaceutical screening and computational biology have enabled the development of novel platforms to target this once 'undruggable' protein. These platforms include DNA encoded library screening, allosteric drug targeting, small-interfering RNA inhibition, CRISPR genome editing, and adoptive cell therapy. Both genetic knock-out models and Cbl-b inhibitors have been shown to reverse immunosuppression in the TME, stimulate cytotoxic T cell activity, and promote tumor regression, findings augmented with PD1 blockade in experimental models. In translating Cbl-b inhibitors to clinic, we propose specific gene expression profiles that may identify patient populations most likely to benefit. Overall, novel Cbl-b inhibitors provide antigen-specific immune stimulation and are a promising therapeutic tool in the field of immuno-oncology.

Exhausted T cells hijacking the cancer-immunity cycle: Assets and liabilities

T cell exhaustion is an alternative differentiation path of T cells, sometimes described as a dysfunction. During the last decade, insights of T cell exhaustion acting as a bottle neck in the field of cancer immunotherapy have undoubtedly provoked attention. One of the main drivers of T cell exhaustion is prolonged antigen presentation, a prerequisite in the cancer-immunity cycle. The umbrella term "T cell exhaustion" comprises various stages of T cell functionalities, describing the dynamic, one-way exhaustion process. Together these qualities of T cells at the exhaustion continuum can enable tumor clearance, but if the exhaustion acquired timeframe is exceeded, tumor cells have increased possibilities of escaping immune system surveillance. This could be considered a tipping point where exhausted T cells switch from an asset to a liability. In this review, the contrary role of exhausted T cells is discussed.

First-in-human phase I/II, open-label study of the anti-OX40 agonist INCAGN01949 in patients with advanced solid tumors

BACKGROUND

OX40 is a costimulatory receptor upregulated on antigen-activated T cells and constitutively expressed on regulatory T cells (Tregs). INCAGN01949, a fully human immunoglobulin G1κ anti-OX40 agonist monoclonal antibody, was designed to promote tumor-specific immunity by effector T-cell activation and Fcγ receptor-mediated Treg depletion. This first-in-human study was conducted to determine the safety, tolerability, and preliminary efficacy of INCAGN01949.

METHODS

Phase I/II, open-label, non-randomized, dose-escalation and dose-expansion study conducted in patients with advanced or metastatic solid tumors. Patients received INCAGN01949 monotherapy (7-1400 mg) in 14-day cycles while deriving benefit. Safety measures, clinical activity, pharmacokinetics, and pharmacodynamic effects were assessed and summarized with descriptive statistics.

RESULTS

Eighty-seven patients were enrolled; most common tumor types were colorectal (17.2%), ovarian (8.0%), and non-small cell lung (6.9%) cancers. Patients received a median three (range 1-9) prior therapies, including immunotherapy in 24 patients (27.6%). Maximum tolerated dose was not reached; one patient (1.1%) receiving 350 mg dose reported dose-limiting toxicity of grade 3 colitis. Treatment-related adverse events were reported in 45 patients (51.7%), with fatigue (16 (18.4%)), rash (6 (6.9%)), and diarrhea (6 (6.9%)) being most frequent. One patient (1.1%) with metastatic gallbladder cancer achieved a partial response (duration of 6.3 months), and 23 patients (26.4%) achieved stable disease (lasting >6 months in one patient). OX40 receptor occupancy was maintained over 90% among all patients receiving doses of ≥200 mg, while no treatment-emergent antidrug antibodies were detected across all dose levels. Pharmacodynamic results demonstrated that treatment with INCAGN01949 did not enhance proliferation or activation of T cells in peripheral blood or reduce circulating Tregs, and analyses of tumor biopsies did not demonstrate any consistent increase in effector T-cell infiltration or function, or decrease in infiltrating Tregs.

CONCLUSION

No safety concerns were observed with INCAGN01949 monotherapy in patients with metastatic or advanced solid tumors. However, tumor responses and pharmacodynamic effects on T cells in peripheral blood and post-therapy tumor biopsies were limited. Studies evaluating INCAGN01949 in combination with other therapies are needed to further evaluate the potential of OX40 agonism as a therapeutic approach in patients with advanced solid tumors.

TRIAL REGISTRATION NUMBER

NCT02923349.

Tumor-infiltrating OX40+ lymphocytes is an independent positive prognostic factor for patients with pancreatic ductal adenocarcinoma

PURPOSE

OX40 signaling pathway occupies a vital place in anti-tumor immunity; however, the role of tumor-infiltrating OX40+ lymphocytes in pancreatic ductal adenocarcinoma (PDAC) remains to be identified.

METHODS

A total of 325 sequential PDAC patients who received curative tumor resection between January 2014 and December 2016 were enrolled. Tissues of these patients were immunohistochemically assessed for tumor infiltration of CD4+ T cells, CD8+ cytotoxic T cells (CTLs), and OX40+ lymphocytes. The frequency of OX40+ tumor-infiltrating lymphocytes (TILs) was then analyzed to various clinicopathological features, densities of tumor infiltration of CD4+ T cells and CTLs, and survival analysis was conducted using Kaplan-Meier (KM) curves. The risk scores of associated markers were calculated by the Cox proportional-hazards model.

RESULTS

Our results showed that higher OX40+ lymphocytes infiltration was significantly correlated with superior median overall survival (OS) (25.8 vs 13.4 months, P < 0.001). Additionally, using univariate and multivariate Cox proportional hazards analyses, this study revealed that together with tumor differentiation, tumor size, serum CA199 levels, serum CA125 levels, and the infiltration of intratumoral CD8+ T cells. The abundance of OX40+ lymphocytes within the tumor was continued to be an independent predictor for OS (P = 0.023, HR = 0.713, 95% CI: 0.532-0.954).

CONCLUSIONS

This study demonstrated that intratumoral infiltration by a high number of OX40+ lymphocytes is a novel biomarker for favorable prognosis in resected PDAC patients, which implies that OX40-agonist-based immunotherapy might be a potential target in PDAC patients.

Development of OX40 agonists for canine cancer immunotherapy

Recent breakthroughs in cancer immunotherapy have provided unprecedented clinical benefits to human cancer patients. Cancer is also one of the most common causes of death in pet dogs. Thus, canine-specific immune therapies targeting similar signaling pathways can provide better treatment options for canine cancer patients. Here, we describe the development and characterization of two canine-specific anti-OX40 agonists to activate OX40 signaling. We show that canine OX40, like human OX40, is not expressed on resting T cells, and its expression is markedly increased on canine CD4 T cells and Tregs after stimulation with concanavalin A (Con-A). cOX40 is also expressed on tumor-infiltrating lymphocytes (TILs) in canine osteosarcoma patients. The canine-specific OX40 agonists strongly activates cPBMCs by increasing IFN-γ expression and do not require Fc receptor-mediated cross-linking for OX40 agonism. Together, these results suggest that cFcOX40L proteins are potent OX40 agonists and have the potential to enhance antitumor immunity in canine cancer patients.

Structural Basis of a Novel Agonistic Anti-OX40 Antibody

Agonistic antibodies targeting co-stimulating receptor OX40 on T cells are considered as important as (or complementary to) the immune checkpoint blockers in cancer treatment. However, none of these agonistic antibodies have reached the late stage of clinical development partially due to the lack of intrinsic potency with the correlation between binding epitope and activity of the antibody not well understood. Here, we identified a novel anti-OX40 agonistic antibody DF004, which stimulated the proliferation of human CD4⁺ T cells in vitro and inhibited tumor growth in a mouse model. Our crystallography structural studies showed that DF004 binds to the CRD2 region of OX40 while RG7888, an OX40 agonist antibody developed by Roche, binds to CRD3 of OX40 to the diametrically opposite position of DF004. This suggests that the agonistic activities of the antibodies are not necessarily epitope dependent. As their agonistic activities critically depend on clustering or cross-linking, our structural modeling indicates that the agonistic activity requires the optimal positioning of three Fc receptor/antibody/OX40 complexes on the cell membrane to facilitate the formation of one intracellular hexameric TRAF complex for downstream signal transduction, which is relatively inefficient. This may explain the lack of sufficient potency of these OX40 antibodies in a therapeutic setting and sheds light on the development of cross-linking-independent agonistic antibodies.

Current status and perspective of tumor immunotherapy for head and neck squamous cell carcinoma

Head and neck squamous cell carcinoma (HNSCC) have a high incidence and mortality rate, and investigating the pathogenesis and potential therapeutic strategies of HNSCC is required for further progress. Immunotherapy is a considerable therapeutic strategy for HNSCC due to its potential to produce a broad and long-lasting antitumor response. However, immune escape, which involves mechanisms including dyregulation of cytokines, perturbation of immune checkpoints, and recruitment of inhibitory cell populations, limit the efficacy of immunotherapy. Currently, multiple immunotherapy strategies for HNSCC have been exploited, including immune checkpoint inhibitors, costimulatory agonists, antigenic vaccines, oncolytic virus therapy, adoptive T cell transfer (ACT), and epidermal growth factor receptor (EGFR)-targeted therapy. Each of these strategies has unique advantages, and the appropriate application of these immunotherapies in HNSCC treatment has significant value for patients. Therefore, this review comprehensively summarizes the mechanisms of immune escape and the characteristics of different immunotherapy strategies in HNSCC to provide a foundation and consideration for the clinical treatment of HNSCC.

First-In-Human Phase I Study of the OX40 Agonist MOXR0916 in Patients with Advanced Solid Tumors

PURPOSE

OX40, a receptor transiently expressed by T cells upon antigen recognition, is associated with costimulation of effector T cells and impairment of regulatory T-cell function. This first-in-human study evaluated MOXR0916, a humanized effector-competent agonist IgG1 monoclonal anti-OX40 antibody.

PATIENTS AND METHODS

Eligible patients with locally advanced or metastatic refractory solid tumors were treated with MOXR0916 intravenously once every 3 weeks (Q3W). A 3+3 dose-escalation stage (0.2-1,200 mg; n = 34) was followed by expansion cohorts at 300 mg (n = 138) for patients with melanoma, renal cell carcinoma, non-small cell lung carcinoma, urothelial carcinoma, and triple-negative breast cancer.

RESULTS

MOXR0916 was well tolerated with no dose-limiting toxicities observed. An MTD was not reached. Most patients (95%) experienced at least one adverse event (AE); 56% of AEs, mostly grade 1-2, were related to MOXR0916. Most common treatment-related AEs included fatigue (17%), diarrhea (8%), myalgia (7%), nausea (6%), decreased appetite (6%), and infusion-related reaction (5%). Pharmacokinetic (PK) parameters were dose proportional between 80 and 1,200 mg and supported Q3W administration. The recommended expansion dose based on PK and OX40 receptor saturation was 300 mg Q3W. Immune activation and upregulation of PD-L1 was observed in a subset of paired tumor biopsies. One renal cell carcinoma patient experienced a confirmed partial response. Overall, 33% of patients achieved stable disease.

CONCLUSIONS

Although objective responses were rarely observed with MOXR0916 monotherapy, the favorable safety profile and evidence of tumor immune activation in a subset of patients support further investigation in combination with complementary agents such as PD-1/PD-L1 antagonists.

Cutting-Edge: Preclinical and Clinical Development of the First Approved Lag-3 Inhibitor

Immune checkpoint inhibitors (ICIs) have revolutionized medical practice in oncology since the FDA approval of the first ICI 11 years ago. In light of this, Lymphocyte-Activation Gene 3 (LAG-3) is one of the most important next-generation immune checkpoint molecules, playing a similar role as Programmed cell Death protein 1 (PD-1) and Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4). 19 LAG-3 targeting molecules are being evaluated at 108 clinical trials which are demonstrating positive results, including promising bispecific molecules targeting LAG-3 simultaneously with other ICIs. Recently, a new dual anti-PD-1 (Nivolumab) and anti-LAG-3 (Relatimab) treatment developed by Bristol Myers Squibb (Opdualag), was approved by the Food and Drug Administration (FDA) as the first LAG-3 blocking antibody combination for unresectable or metastatic melanoma. This novel immunotherapy combination more than doubled median progression-free survival (PFS) when compared to nivolumab monotherapy (10.1 months versus 4.6 months). Here, we analyze the large clinical trial responsible for this historical approval (RELATIVITY-047), and discuss the preclinical and clinical developments that led to its jump into clinical practice. We will also summarize results achieved by other LAG-3 targeting molecules with promising anti-tumor activities currently under clinical development in phases I, I/II, II, and III. Opdualag will boost the entry of more LAG-3 targeting molecules into clinical practice, supporting the accumulating evidence highlighting the pivotal role of LAG-3 in cancer.

Antibody-Targeted TNFRSF Activation for Cancer Immunotherapy: The Role of FcγRIIB Cross-Linking

Co-stimulation signaling in various types of immune cells modulates immune responses in physiology and disease. Tumor necrosis factor receptor superfamily (TNFRSF) members such as CD40, OX40 and CD137/4-1BB are expressed on myeloid cells and/or lymphocytes, and they regulate antigen presentation and adaptive immune activities. TNFRSF agonistic antibodies have been evaluated extensively in preclinical models, and the robust antitumor immune responses and efficacy have encouraged continued clinical investigations for the last two decades. However, balancing the toxicities and efficacy of TNFRSF agonistic antibodies remains a major challenge in the clinical development. Insights into the co-stimulation signaling biology, antibody structural roles and their functionality in immuno-oncology are guiding new advancement of this field. Leveraging the interactions between antibodies and the inhibitory Fc receptor FcγRIIB to optimize co-stimulation agonistic activities dependent on FcγRIIB cross-linking selectively in tumor microenvironment represents the current frontier, which also includes cross-linking through tumor antigen binding with bispecific antibodies. In this review, we will summarize the immunological roles of TNFRSF members and current clinical studies of TNFRSF agonistic antibodies. We will also cover the contribution of different IgG structure domains to these agonistic activities, with a focus on the role of FcγRIIB in TNFRSF cross-linking and clustering bridged by agonistic antibodies. We will review and discuss several Fc-engineering approaches to optimize Fc binding ability to FcγRIIB in the context of proper Fab and the epitope, including a cross-linking antibody (xLinkAb) model and its application in developing TNFRSF agonistic antibodies with improved efficacy and safety for cancer immunotherapy.

Safety and tolerability of MEDI0562, an OX40 agonist monoclonal antibody, in combination with durvalumab or tremelimumab in adult patients with advanced solid tumors

PURPOSE

Combination therapies targeting immunological checkpoints have shown promise in treating multiple tumor types. We report safety and tolerability of MEDI0562, a humanized IgG1K OX40 monoclonal antibody, in combination with durvalumab (anti-PD-L1), or tremelimumab (anti-CTLA-4), in adult patients with previously treated advanced solid tumors.

EXPERIMENTAL DESIGN

In this phase 1, multicenter, open-label study, patients received escalating doses of MEDI0562 (2.25, 7.5, or 22.5 mg) every two weeks (Q2W) in combination with durvalumab (1500 mg) or tremelimumab (75 or 225 mg) Q4W, intravenously, until unacceptable toxicity or progressive disease. Tumor assessments were performed Q8W. The primary objective was to evaluate safety and tolerability.

RESULTS

Among the 27 and 31 patients who received MEDI0562 + durvalumab or MEDI0562 + tremelimumab, 74.1% and 67.7% reported a treatment-related adverse event (AE), and 22.2% and 19.4% experienced a treatment‑emergent AE that led to discontinuation, respectively. The maximum tolerated dose of MEDI0562 + durvalumab was 7.5 mg MEDI0562 + 1500 mg durvalumab; the maximum administered dose of MEDI0562 + tremelimumab was 22.5 mg MEDI0562 + 225 mg tremelimumab. Three patients in the MEDI0562 + durvalumab arm had a partial response. The mean percentage of Ki67+CD4+ and Ki67+CD8+ memory T cells increased by >100% following the first dose of MEDI0562 + durvalumab or tremelimumab in all dose cohorts. A decrease in OX40+FOXP3 T regulatory cells was observed in a subset of patients with available paired biopsies.

CONCLUSIONS

Following dose escalation, moderate toxicity was observed in both treatment arms, with no clear efficacy signals demonstrated.

The Treatment of Advanced Melanoma: Therapeutic Update

Cutaneous melanoma is the main cause of death for skin cancer. The majority of patients with a diagnosis of melanoma have localized disease, which can be successfully treated with surgical treatment. However, the surgical approach is not curative for advanced melanoma (AM). Indeed, the management of AM is still challenging, since melanoma is the solid tumor with the highest number of mutations and cancer cells have the capacity to evade the immune system. In the past, the treatment of AM relied on chemotherapeutic agents, without showing efficacy data. Recent knowledge on melanoma pathogenesis as well as the introduction of immunotherapies, targeted therapies vaccines, small molecules, and combination therapies has revolutionized AM management, showing promising results in terms of effectiveness and safety. The aim of this review is to assess and to discuss the role of emerging therapies for AM management in order to obtain a complete overview of the currently available treatment options and future perspectives.

OX40 and 4-1BB delineate distinct immune profiles in sarcoma

Systemic relapse after radiotherapy and surgery is the major cause of disease-related mortality in sarcoma patients. Combining radiotherapy and immunotherapy is under investigation as a means to improve response rates. However, the immune contexture of sarcoma is understudied. Here, we use a retrospective cohort of sarcoma patients, treated with neoadjuvant radiotherapy, and TCGA data. We explore therapeutic targets of relevance to sarcoma, using genomics and multispectral immunohistochemistry to provide insights into the tumor immune microenvironment across sarcoma subtypes. Differential gene expression between radioresponsive myxoid liposarcoma (MLPS) and more radioresistant undifferentiated pleomorphic sarcoma (UPS) indicated UPS contained higher transcript levels of a number of immunotherapy targets (CD73/NT5E, CD39/ENTPD1, CD25/IL2RA, and 4-1BB/TNFRSF9). We focused on 4-1BB/TNFRSF9 and other costimulatory molecules. In TCGA data, 4-1BB correlated to an inflamed and exhausted phenotype. OX40/TNFRSF4 and 4-1BB/TNFRSF9 were highly expressed in sarcoma subtypes versus other cancers. Despite OX40 and 4-1BB being described as Treg markers, we identified that they delineate distinct tumor immune profiles. This was true for sarcoma and other cancers. While only a limited number of samples could be analyzed, spatial analysis of OX40 expression identified two diverse phenotypes of OX40+ Tregs, one associated with and one independent of tertiary lymphoid structures (TLSs). Patient stratification is of intense interest for immunotherapies. We provide data supporting the viewpoint that a cohort of sarcoma patients, appropriately selected, are promising candidates for immunotherapies. Spatial profiling of OX40+ Tregs, in relation to TLSs, could be an additional metric to improve future patient stratification.

Current Clinical Trial Landscape of OX40 Agonists

PURPOSE OF REVIEW

Despite the efficacy of immune checkpoint blockade (ICB) immunotherapy, most cancer patients still develop progressive disease necessitating additional treatment options. One approach is ligation of the OX40 (CD134) costimulatory receptor which promotes T cell activation, effector function, and the generation of long-lived memory cells.

RECENT FINDINGS

Numerous preclinical studies have demonstrated that OX40 agonists alone or in combination with ICB (e.g., anti-PD-1, anti-PD-L1, and anti-CTLA-4) augment anti-tumor immunity. In this review, we discuss the impact of OX40 agonists on T cell function and the therapeutic potential of OX40 agonists alone or in conjunction with ICB for patients with advanced malignancies.

Therapeutic targeting miR130b counteracts diffuse large B-cell lymphoma progression via OX40/OX40L-mediated interaction with Th17 cells

MicroRNAs (miRNAs) are involved in lymphoma progression by regulating the tumor microenvironment. Serum miR130b is overexpressed in diffuse large B-cell lymphoma (DLBCL), inducing Th17 cell alterations. To further illustrate its biological significance and therapeutic rationale, miR130b was detected by quantitative real-time PCR in the serum samples of 532 newly diagnosed DLBCL patients. The mechanism of miR130b on lymphoma progression and the tumor microenvironment was investigated both in vitro and in vivo. Therapeutic targeting miR130b was also evaluated, including OX40 agonistic antibody and lipid nanoparticles (LNPs)-miR130b antagomir. The results showed that serum miR130b significantly correlated with tumor miR130b and serum interleukin-17, indicating lymphoma relapse and inferior survival of DLBCL patients. MiR130b overexpression altered tumor microenvironment signaling pathways and increased Th17 cell activity. As mechanism of action, miR130b downregulated tumor OX40L expression by directly targeting IFNAR1/p-STAT1 axis, recruiting Th17 cells via OX40/OX40L interaction, thereby promoting immunosuppressive function of Th17 cells. In co-culture systems of B-lymphoma cells with immune cells, miR130b inhibited lymphoma cell autophagy, which could be counteracted by OX40 agonistic antibody and LNPs-miR130b antagomir. In murine xenograft model established with subcutaneous injection of A20 cells, both OX40 agonistic antibody and LNPs-miR130b antagomir remarkably inhibited Th17 cells and retarded miR130b-overexpressing tumor growth. In conclusion, as an oncogenic biomarker of DLBCL, miR130b was related to lymphoma progression through modulating OX40/OX40L-mediated lymphoma cell interaction with Th17 cells, attributing to B-cell lymphoma sensitivity towards OX40 agonistic antibody. Targeting miR130b using LNPs-miR130b antagomir could also be a potential immunotherapeutic strategy in treating OX40-altered lymphoid malignancies.

T-cell subsets in the skin and their role in inflammatory skin disorders

T lymphocytes (T cells) are major players of the adaptive immune response. Naive T cells are primed in the presence of cytokines, leading to polarization into distinct T-cell subsets with specific functions. These subsets are classified based on their T-cell receptor profile, expression of transcription factors, surface cytokine and chemokine receptors, and their cytokine production, which together determine their specific function. This review provides an overview of the various T-cell subsets and their function in several inflammatory skin disorders ranging from allergic inflammation to skin tumors. Moreover, we highlight similarities of T-cell responses across different skin disorders, demonstrating the presence of similar and opposing functions for the different T-cell subsets. Finally, we discuss the effects of currently available and promising therapeutic approaches to harness T cells in inflammatory skin diseases for which efficacy next to unwanted side effects provide new insights into the pathophysiology of skin disorders.

Fc-based Duokines: dual-acting costimulatory molecules comprising TNFSF ligands in the single-chain format fused to a heterodimerizing Fc (scDk-Fc)

Targeting costimulatory receptors of the tumor necrosis factor superfamily (TNFSF) to activate T-cells and promote anti-tumor T-cell function have emerged as a promising strategy in cancer immunotherapy. Previous studies have shown that combining two different members of the TNFSF resulted in dual-acting costimulatory molecules with the ability to activate two different receptors either on the same cell or on different cell types. To achieve prolonged plasma half-life and extended drug disposition, we have developed novel dual-acting molecules by fusing single-chain ligands of the TNFSF to heterodimerizing Fc chains (scDuokine-Fc, scDk-Fc). Incorporating costimulatory ligands of the TNF superfamily into a scDk-Fc molecule resulted in enhanced T-cell proliferation translating in an increased anti-tumor activity in combination with a primary T-cell-activating bispecific antibody. Our data show that the scDk-Fc molecules are potent immune-stimulatory molecules that are able to enhance T-cell mediated anti-tumor responses.

Immunotherapy of Cancer by Targeting Regulatory T cells

Regulatory T (Treg) cells maintain immune homeostasis by inhibiting abnormal/overactive immune responses to both autogenic and nonautogenic antigens. Treg cells play an important role in immune tolerance, autoimmune diseases, infectious diseases, organ transplantation, and tumor diseases. Treg cells have two functional characteristics: T cell anergy and immunosuppression. Treg cells remain immune unresponsive to high concentrations of interleukin-2 and anti-CD3 monoclonal antibodies. In addition, the activation of Treg cells after TCR-mediated signal stimulation inhibits the activation and proliferation of effector T cells. In the process of tumor development, Treg cells accumulate locally in the tumor and lead to tumor escape by inducing anergy and immunosuppression. It is believed that targeted elimination of Treg cells can activate tumor-specific effector T cells and improve the efficiency of cancer immunotherapy. Therefore, inhibition/clearance of Treg cells is a promising strategy for enhancing antitumor immunity. Here, we review studies of cancer immunotherapies targeting Treg cells.

Immunotherapy for Melanoma

Melanoma is the leading cause of death from skin cancer and is responsible for over 7000 deaths in the USA each year alone. For many decades, limited treatment options were available for patients with metastatic melanoma; however, over the last decade, a new era in treatment dawned for oncologists and their patients. Targeted therapy with BRAF and MEK inhibitors represents an important cornerstone in the treatment of metastatic melanoma; however, this chapter carefully reviews the past and current therapy options available, with a significant focus on immunotherapy-based approaches. In addition, we provide an overview of the results of recent advances in the adjuvant setting for patients with resected stage III and stage IV melanoma, as well as in patients with melanoma brain metastases. Finally, we provide a brief overview of the current research efforts in the field of immuno-oncology for melanoma.

A Phase I, Open-Label, Dose-Escalation Study of the OX40 Agonist Ivuxolimab in Patients with Locally Advanced or Metastatic Cancers

PURPOSE

Stimulation of effector T cells is an appealing immunotherapeutic approach in oncology. OX40 (CD134) is a costimulatory receptor expressed on activated CD4⁺ and CD8⁺ T cells. Induction of OX40 following antigen recognition results in enhanced T-cell activation, proliferation, and survival, and OX40 targeting shows therapeutic efficacy in preclinical studies. We report the monotherapy dose-escalation portion of a multicenter, phase I trial (NCT02315066) of ivuxolimab (PF-04518600), a fully human immunoglobulin G2 agonistic monoclonal antibody specific for human OX40.

PATIENTS AND METHODS

Adult patients (N = 52) with selected locally advanced or metastatic cancers received ivuxolimab 0.01 to 10 mg/kg. Primary endpoints were safety and tolerability. Secondary/exploratory endpoints included preliminary assessment of antitumor activity and biomarker analyses.

RESULTS

The most common all-causality adverse events were fatigue (46.2%), nausea (28.8%), and decreased appetite (25.0%). Of 31 treatment-related adverse events, 30 (96.8%) were grade ≤2. No dose-limiting toxicities occurred. Ivuxolimab exposure increased in a dose-proportionate manner from 0.3 to 10 mg/kg. Full peripheral blood target engagement occurred at ≥0.3 mg/kg. Three (5.8%) patients achieved a partial response, and disease control was achieved in 56% of patients. Increased CD4⁺ central memory T-cell proliferation and activation, and clonal expansion of CD4⁺ and CD8⁺ T cells in peripheral blood were observed at 0.1 to 3.0 mg/kg. Increased immune cell infiltrate and OX40 expression were evident in on-treatment tumor biopsies.

CONCLUSIONS

Ivuxolimab was generally well tolerated with on-target immune activation at clinically relevant doses, showed preliminary antitumor activity, and may serve as a partner for combination studies.

Signal pathways of melanoma and targeted therapy

Melanoma is the most lethal skin cancer that originates from the malignant transformation of melanocytes. Although melanoma has long been regarded as a cancerous malignancy with few therapeutic options, increased biological understanding and unprecedented innovations in therapies targeting mutated driver genes and immune checkpoints have substantially improved the prognosis of patients. However, the low response rate and inevitable occurrence of resistance to currently available targeted therapies have posed the obstacle in the path of melanoma management to obtain further amelioration. Therefore, it is necessary to understand the mechanisms underlying melanoma pathogenesis more comprehensively, which might lead to more substantial progress in therapeutic approaches and expand clinical options for melanoma therapy. In this review, we firstly make a brief introduction to melanoma epidemiology, clinical subtypes, risk factors, and current therapies. Then, the signal pathways orchestrating melanoma pathogenesis, including genetic mutations, key transcriptional regulators, epigenetic dysregulations, metabolic reprogramming, crucial metastasis-related signals, tumor-promoting inflammatory pathways, and pro-angiogenic factors, have been systemically reviewed and discussed. Subsequently, we outline current progresses in therapies targeting mutated driver genes and immune checkpoints, as well as the mechanisms underlying the treatment resistance. Finally, the prospects and challenges in the development of melanoma therapy, especially immunotherapy and related ongoing clinical trials, are summarized and discussed.

Directing T-Cell Immune Responses for Cancer Vaccination and Immunotherapy

Cancer vaccination and immunotherapy revolutionised the treatment of cancer, a result of decades of research into the immune system in health and disease. However, despite recent breakthroughs in treating otherwise terminal cancer, only a minority of patients respond to cancer immunotherapy and some cancers are largely refractive to immunotherapy treatment. This is due to numerous issues intrinsic to the tumour, its microenvironment, or the immune system. CD4+ and CD8+ αβ T-cells emerged as the primary effector cells of the anti-tumour immune response but their function in cancer patients is often compromised. This review details the mechanisms by which T-cell responses are hindered in the setting of cancer and refractive to immunotherapy, and details many of the approaches under investigation to direct T-cell function and improve the efficacy of cancer vaccination and immunotherapy.

Spatial Mapping and Immunomodulatory Role of the OX40/OX40L Pathway in Human Non-Small Cell Lung Cancer

PURPOSE

To evaluate the tissue distribution and clinical significance of OX40 and OX40L in human non-small cell lung cancer (NSCLC).

EXPERIMENTAL DESIGN

Using multiplexed quantitative immunofluorescence, we conducted simultaneous and localized measurements of OX40 and OX40L proteins, major T-cell subsets, and conventional type 1 dendritic cells (cDC1) in 614 primary NSCLCs from three independent cohorts represented in tissue microarrays. We also measured OX40L protein in samples from a phase I clinical trial of intratumor administration of a lipid nanoparticle encapsulated mRNA encoding OX40L (mRNA-2416) in human solid tumors. Finally, we studied the OX40 pathway in 212 uterine/ovarian serous carcinomas.

RESULTS

OX40 protein was expressed in approximately 90% of NSCLCs, and OX40L was detected in approximately 10% of cases. Increased expression of OX40 was associated with higher CD4⁺ and CD8⁺ T lymphocytes, as well as cDC1s. Elevated expression of OX40L was consistently associated with increased CD4⁺ tumor-infiltrating lymphocytes and longer overall survival. No association was found between OX40 or OX40L levels and oncogenic driver mutations in EGFR and KRAS in lung adenocarcinomas. Delivering OX40L mRNA using intratumor mRNA-2416 injection mediated increased local OX40L protein levels that was most prominent in a patient with ovarian serous carcinoma. Detectable OX40L protein levels were observed in 15% of primary uterine/ovarian serous malignancies and associated with longer survival.

CONCLUSIONS

The OX40 pathway is expressed in a fraction of NSCLCs and is associated with a favorable immune contexture. Although OX40L is uncommonly expressed in NSCLC and serous malignancies, it is associated with better prognosis and can be introduced using exogenous mRNA.

OX40-targeted immune agonist antibodies induce potent antitumor immune responses without inducing liver damage in mice

Despite promising preclinical and clinical data demonstrating that immune agonist antibody immunotherapies (IAAs) such as αOX40 induce strong antitumor immune responses, clinical translation has been significantly hampered by the propensity of some IAAs to induce dose-limiting and sometimes life-threatening immunotoxicities such as cytokine release syndrome and hepatotoxicity. For example, in a recent study αOX40 was shown to induce significant liver damage in mice by inducing the pyroptosis of liver natural killer T cells (NKT) cells. Surprisingly; however, given these previous reports, αOX40 treatment in our hands did not induce NKT cell pyroptosis or liver damage. We investigated numerous potential confounding factors including age, sex, tumor burden, dosing strategy, and the gut microbiota, which could have explained this discrepancy with the previous study. In none of these experiments did we find that αOX40 induced any more than very mild inflammation in the liver. Our study therefore suggests that, preclinically, αOX40 is a safe and effective immunotherapy and further studies into the clinical benefit of αOX40 are warranted.

CD137 as an Attractive T Cell Co-Stimulatory Target in the TNFRSF for Immuno-Oncology Drug Development

Immune checkpoint inhibitors have altered the treatment landscape significantly in several cancers, yet not enough for many cancer patients. T cell costimulatory receptors have been pursued as targets for the next generation of cancer immunotherapies, however, sufficient clinical efficacy has not yet been achieved. CD137 (TNFRSF9, 4-1BB) provides co-stimulatory signals and activates cytotoxic effects of CD8+ T cells and helps to form memory T cells. In addition, CD137 signalling can activate NK cells and dendritic cells which further supports cytotoxic T cell activation. An agonistic monoclonal antibody to CD137, urelumab, provided promising clinical efficacy signals but the responses were achieved above the maximum tolerated dose. Utomilumab is another CD137 monoclonal antibody to CD137 but is not as potent as urelumab. Recent advances in antibody engineering technologies have enabled mitigation of the hepato-toxicity that hampered clinical application of urelumab and have enabled to maintain similar potency to urelumab. Next generation CD137 targeting molecules currently in clinical trials support T cell and NK cell expansion in patient samples. CD137 targeting molecules in combination with checkpoint inhibitors or ADCC-enhancing monoclonal antibodies have been sought to improve both clinical safety and efficacy. Further investigation on patient samples will be required to provide insights to understand compensating pathways for future combination strategies involving CD137 targeting agents to optimize and maintain the T cell activation status in tumors.

Cervical Cancer Immunotherapy: Facts and Hopes

It is a sad fact that despite being almost completely preventable through human papillomavirus (HPV) vaccination and screening, cervical cancer remains the fourth most common cancer to affect women worldwide. Persistent high-risk HPV (hrHPV) infection is the primary etiologic factor for cervical cancer. Upward of 70% of cases are driven by HPV types 16 and 18, with a dozen other hrHPVs associated with the remainder of cases. Current standard-of-care treatments include radiotherapy, chemotherapy, and/or surgical resection. However, they have significant side effects and limited efficacy against advanced disease. There are a few treatment options for recurrent or metastatic cases. Immunotherapy offers new hope, as demonstrated by the recent approval of programmed cell death protein 1-blocking antibody for recurrent or metastatic disease. This might be augmented by combination with antigen-specific immunotherapy approaches, such as vaccines or adoptive cell transfer, to enhance the host cellular immune response targeting HPV-positive cancer cells. As cervical cancer progresses, it can foster an immunosuppressive microenvironment and counteract host anticancer immunity. Thus, approaches to reverse suppressive immune environments and bolster effector T-cell functioning are likely to enhance the success of such cervical cancer immunotherapy. The success of nonspecific immunostimulants like imiquimod against genital warts also suggest the possibility of utilizing these immunotherapeutic strategies in cervical cancer prevention to treat precursor lesions (cervical intraepithelial neoplasia) and persistent hrHPV infections against which the licensed prophylactic HPV vaccines have no efficacy. Here, we review the progress and challenges in the development of immunotherapeutic approaches for the prevention and treatment of cervical cancer.

Looking into a Better Future: Novel Therapies for Metastatic Melanoma

Even though melanoma represents a small percentage of all cutaneous cancers, it is responsible for most deaths from skin neoplasms. In early stages it can be successfully treated with surgery, but as the disease expands the survival rate drops significantly. For many years the mainstay of treatment for metastatic melanoma was chemotherapeutic agents, even though they failed to prove survival prolongation. After the advent of ipilimumab, a survival benefit and better overall response rate could be offered to the patients. Other new therapies, such as immunotherapies, targeted therapies, vaccines, and small molecules, are currently being studied. Also, combination regimens have demonstrated superiority to some monotherapies. Nowadays, ipilimumab should no longer be considered the first-line therapy given its severe toxicity and lower efficacy, while nivolumab remains efficacious and has a good safety profile. T-VEC as monotherapy has been shown to be an elegant alternative even for the elderly or cases of head and neck melanomas. If the BRAF mutation status is positive, the combination of dabrafenib and trametinib could be an option to consider. Despite the success of the novel treatments, their effectiveness is still limited. New studies have opened up new avenues for future research in melanoma treatment, which is expected to lead to better therapeutic outcomes for our patients. The objective of this review is to discuss the novel therapies for metastatic melanoma that have been tested in humans during the last 3 years to obtain a sharper perspective of the available treatment options for specific patient characteristics.

Beyond conventional immune-checkpoint inhibition - novel immunotherapies for renal cell carcinoma

The management of advanced-stage renal cell carcinoma (RCC) has been transformed by the development of immune-checkpoint inhibitors (ICIs). Nonetheless, most patients do not derive durable clinical benefit from these agents. Importantly, unlike other immunotherapy-responsive solid tumours, most RCCs have only a moderate mutational burden, and paradoxically, high levels of tumour CD8+ T cell infiltration are associated with a worse prognosis in patients with this disease. Building on the successes of antibodies targeting the PD-1 and CTLA4 immune checkpoints, multiple innovative immunotherapies are now in clinical development for the treatment of patients with RCC, including ICIs with novel targets, co-stimulatory pathway agonists, modified cytokines, metabolic pathway modulators, cell therapies and therapeutic vaccines. However, the successful development of such novel immune-based treatments and of immunotherapy-based combinations will require a disease-specific framework that incorporates a deep understanding of RCC immunobiology. In this Review, using the structure provided by the well-described cancer-immunity cycle, we outline the key steps required for a successful antitumour immune response in the context of RCC, and describe the development of promising new immunotherapies within the context of this framework. With this approach, we summarize and analyse the most encouraging targets of novel immune-based therapies within the RCC microenvironment, and review the landscape of emerging antigen-directed therapies for this disease.

Beyond First-Line Immune Checkpoint Inhibitor Therapy in Patients With Hepatocellular Carcinoma

Until recently, the treatment landscape for hepatocellular cancer (HCC) was dominated by tyrosine kinase inhibitors (TKIs) which offered an overall survival (OS) benefit when used both in the first-and second-line setting compared to best supportive care. However, the treatment landscape has changed with the introduction of immune checkpoint inhibitors (ICIs) for the treatment of HCC with significant improvement in OS and progression free survival reported with combination atezolizumab and bevacizumab compared to sorafenib in the first-line setting. Nonetheless, the response to ICIs is 20–30% and invariably patients will progress. What remains unclear is which therapeutics should be used following ICI exposure. Extrapolating from the evidence base in renal cell carcinoma, subsequent therapy with TKIs offers both a response and survival benefit and are recommended by European guidelines. However, there are a number of novel therapies emerging that target mechanisms of ICI resistance that hold promise both in combination with ICI or as subsequent therapy. This paper will discuss the evidence for ICIs in HCC, the position of second-line therapies following ICIs and research strategies moving forward.

Beyond PD-1: The Next Frontier for Immunotherapy in Melanoma

The advent of first and second-generation immune checkpoint blockade (ICI) has resulted in improved survival of patients with metastatic melanoma over the past decade. However, the majority of patients ultimately progress despite these treatments, which has served as an impetus to consider a range of subsequent therapies. Many of the next generation of immunotherapeutic agents focus on modifying the immune system to overcome resistance to checkpoint blockade. ICI resistance can be understood as primary, or acquired-where the latter is the most common scenario. While there are several postulated mechanisms by which resistance, particularly acquired resistance, occurs, the predominant escape mechanisms include T cell exhaustion, upregulation of alternative inhibitory checkpoint receptors, and alteration of the tumor microenvironment (TME) into a more suppressive, anti-inflammatory state. Therapeutic agents in development are designed to work by combating one or more of these resistance mechanisms. These strategies face the added challenge of minimizing immune-related toxicities, while improving antitumor efficacy. This review focuses upon the following categories of novel therapeutics: 1) alternative inhibitory receptor pathways; 2) damage- or pathogen-associated molecular patterns (DAMPs/PAMPs); and 3) immune cell signaling mediators. We present the current state of these therapies, including preclinical and clinical data available for these targets under development.

How Do We Meet the Challenge of Chimeric Antigen Receptor T-Cell Therapy for Solid Tumors?

ABSTRACT

Immune checkpoint inhibition has vastly improved the treatment of solid tumors, but most patients do not experience durable clinical benefit, so novel immunotherapeutic approaches are needed. Autologous T cells genetically engineered to express chimeric antigen receptors (CARs) have led to unprecedented clinical success in hematologic malignancies, and increasing efforts are actively being pursued to translate these benefits to the solid tumor arena. However, solid tumors present unique challenges for CAR T-cell development. In this review, we examine the potential barriers to progress and present emerging approaches to overcome these challenges with CAR therapy in solid tumors.

Update of early phase clinical trials in cancer immunotherapy

Immunotherapy has revolutionized the landscape of cancer treatment and become a standard pillar of the treatment. The two main drivers, immune checkpoint inhibitors and chimeric antigen receptor T cells, contributed to this unprecedented success. However, despite the striking clinical improvements, most patients still suffer from disease progression because of the evolution of primary or acquired resistance. This mini-review summa-rizes new treatment options including novel targets and interesting combinational approaches to increase our understanding of the mechanisms of the action of and resistance to immunotherapy, to expand our knowledge of advances in biomarker and therapeutics development, and to help to find the most appropriate option or a way of overcoming the resistance for cancer patients.

Update of early phase clinical trials in cancer immunotherapy

Immunotherapy has revolutionized the landscape of cancer treatment and become a standard pillar of the treatment. The two main drivers, immune checkpoint inhibitors and chimeric antigen receptor T cells, contributed to this unprecedented success. However, despite the striking clinical improvements, most patients still suffer from disease progression because of the evolution of primary or acquired resistance. This mini-review summarizes new treatment options including novel targets and interesting combinational approaches to increase our understanding of the mechanisms of the action of and resistance to immunotherapy, to expand our knowledge of advances in biomarker and therapeutics development, and to help to find the most appropriate option or a way of overcoming the resistance for cancer patients. [BMB Reports 2021; 54(1): 70-88].

The Impact of Tregs on the Anticancer Immunity and the Efficacy of Immune Checkpoint Inhibitor Therapies

Although cancers arise from genetic mutations enabling cells to proliferate uncontrollably, they cannot thrive without failure of the anticancer immunity due in a large part to the tumor environment's influence on effector and regulatory T cells. The field of immune checkpoint inhibitor (ICI) therapy for cancer was born out of the fact that tumor environments paralyze the immune cells that are supposed to clear them by activating the immune checkpoint molecules such as PD-1. While various subsets of effector T cells work collaboratively to eliminate cancers, Tregs enriched in the tumor environment can suppress not only the native anticancer immunity but also diminish the efficacy of ICI therapies. Because of their essential role in suppressing autoimmunity, various attempts to specifically deplete tumor-associated Tregs are currently underway to boost the efficacy of ICI therapies without causing systemic autoimmune responses. A better understanding the roles of Tregs in the anti-cancer immunity and ICI therapies should provide more specific targets to deplete intratumoral Tregs. Here, we review the current understanding on how Tregs inhibit the anti-cancer immunity and ICI therapies as well as the advances in the targeted depletion of intratumoral Tregs.

Tumor Microenvironment and Immunotherapy Response in Head and Neck Cancer

The tumor microenvironment (TME) encompasses cellular and non-cellular components which play an important role in tumor evolution, invasion, and metastasis. A complicated interplay between tumor cells and adjacent TME cells, such as stromal cells, immune cells, inflammatory cells, and cytokines, leads to severe immunosuppression and the proliferation of cancer cells in several solid tumors. An immunosuppressive TME has a significant impact on treatment resistance and may guide response to immunotherapy. In head and neck cancer (HNC), immunotherapeutic drugs have been incorporated in everyday clinical practice. However, despite an exceptional rate of durable responses, only a low percentage of patients respond. In this review, we will focus on the complex interactions occurring in this dynamic system, the TME, which orchestrate key events that lead to tumor progression, immune escape, and resistance. Furthermore, we will summarize current clinical trials that depict the TME as a potential therapeutic target for improved patient selection.

OX40 Agonist BMS-986178 Alone or in Combination With Nivolumab and/or Ipilimumab in Patients With Advanced Solid Tumors

PURPOSE

This phase I/IIa study (NCT02737475) evaluated the safety and activity of BMS-986178, a fully human OX40 agonist IgG1 mAb, ± nivolumab and/or ipilimumab in patients with advanced solid tumors.

PATIENTS AND METHODS

Patients (with non-small cell lung, renal cell, bladder, other advanced cancers) received BMS-986178 (20-320 mg) ± nivolumab (240-480 mg) and/or ipilimumab (1-3 mg/kg). The primary endpoint was safety. Additional endpoints included immunogenicity, pharmacodynamics, pharmacokinetics, and antitumor activity per RECIST version 1.1.

RESULTS

Twenty patients received BMS-986178 monotherapy, and 145 received combination therapy in various regimens (including two patients receiving nivolumab monotherapy). With a follow-up of 1.1 to 103.6 weeks, the most common (≥5%) treatment-related adverse events (TRAEs) included fatigue, pruritus, rash, pyrexia, diarrhea, and infusion-related reactions. Overall, grade 3-4 TRAEs occurred in one of 20 patients (5%) receiving BMS-986178 monotherapy, six of 79 (8%) receiving BMS-986178 plus nivolumab, zero of two receiving nivolumab monotherapy, six of 41 (15%) receiving BMS-986178 plus ipilimumab, and three of 23 (13%) receiving BMS-986178 plus nivolumab plus ipilimumab. No deaths occurred. No dose-limiting toxicities were observed with monotherapy, and the MTD was not reached in either the monotherapy or the combination escalation cohorts. No objective responses were seen with BMS-986178 alone; objective response rates ranged from 0% to 13% across combination therapy cohorts.

CONCLUSIONS

In this study, BMS-986178 ± nivolumab and/or ipilimumab appeared to have a manageable safety profile, but no clear efficacy signal was observed above that expected for nivolumab and/or ipilimumab.

T-cell agonists in cancer immunotherapy

Cancer cells can evade immune surveillance in the body. However, immune checkpoint inhibitors can interrupt this evasion and enhance the antitumor activity of T cells. Other mechanisms for promoting antitumor T-cell function are the targeting of costimulatory molecules expressed on the surface of T cells, such as 4-1BB, OX40, inducible T-cell costimulator and glucocorticoid-induced tumor necrosis factor receptor. In addition, CD40 targets the modulation of the activation of antigen-presenting cells, which ultimately leads to T-cell activation. Agonists of these costimulatory molecules have demonstrated promising results in preclinical and early-phase trials and are now being tested in ongoing clinical trials. In addition, researchers are conducting trials of combinations of such immune modulators with checkpoint blockade, radiotherapy and cytotoxic chemotherapeutic drugs in patients with advanced tumors. This review gives a comprehensive picture of the current knowledge of T-cell agonists based on their use in recent and ongoing clinical trials.