Routes of delivery for CpG and anti-CD137 for the treatment of orthotopic kidney tumors in mice

In Situ Tumor Vaccination with Nanoparticle Co-Delivering CpG and STAT3 siRNA to Effectively Induce Whole-Body Antitumor Immune Response

The success of immunotherapy with immune checkpoint inhibitors (ICIs) in a subset of individuals has been very exciting. However, in many cancers, responses to current ICIs are modest and are seen only in a small subsets of patients. Herein, a widely applicable approach that increases the benefit of ICIs is reported. Intratumoral administration of augmenting immune response and inhibiting suppressive environment of tumors-AIRISE-02 nanotherapeutic that co-delivers CpG and STAT3 siRNA-results in not only regression of the injected tumor, but also tumors at distant sites in multiple tumor model systems. In particular, three doses of AIRISE-02 in combination with systemic ICIs completely cure both treated and untreated aggressive melanoma tumors in 63% of mice, while ICIs alone do not cure any mice. A long-term memory immune effect is also reported. AIRISE-02 is effective in breast and colon tumor models as well. Lastly, AIRISE-02 is well tolerated in mice and nonhuman primates. This approach combines multiple therapeutic agents into a single nanoconstruct to create whole-body immune responses across multiple cancer types. Being a local therapeutic, AIRISE-02 circumvents regulatory challenges of systemic nanoparticle delivery, facilitating rapid translation to the clinic. AIRISE-02 is under investigational new drug (IND)-enabling studies, and clinical trials will soon follow.

CD137+ T-Cells: Protagonists of the Immunotherapy Revolution

Simple Summary

The CD137 receptor is expressed by activated antigen-specific T-cells. CD137⁺ T-cells were identified inside TILs and PBMCs of different tumor types and have proven to be the naturally occurring antitumor effector cells, capable of expressing a wide variability in terms of TCR specificity against both shared and neoantigenic tumor-derived peptides. The aim of this review is thus summarizing and highlighting their role as drivers of patients’ immune responses in anticancer therapies as well as their potential role in future and current strategies of immunotherapy.

Abstract

The CD137 receptor (4-1BB, TNF RSF9) is an activation induced molecule expressed by antigen-specific T-cells. The engagement with its ligand, CD137L, is capable of increasing T-cell survival, proliferation, and cytokine production. This allowed to identify the CD137⁺ T-cells as the real tumor-specific activated T-cell population. In fact, these cells express various TCRs that are specific for a wide range of tumor-derived peptides, both shared and neoantigenic ones. Moreover, their prevalence in sites close to the tumor and their unicity in killing cancer cells both in vitro and in vivo, raised particular interest in studying their potential role in different strategies of immunotherapy. They indeed showed to be a reliable marker able to predict patient’s outcome to immune-based therapies as well as monitor their response. In addition, the possibility of isolating and expanding this population, turned promising in order to generate effector antitumor T-cells in the context of adoptive T-cell therapies. CD137-targeting monoclonal antibodies have already shown their antitumor efficacy in cancer patients and a number of clinical trials are thus ongoing to test their possible introduction in different combination approaches of immunotherapy. Finally, the intracellular domain of the CD137 receptor was introduced in the anti-CD19 CAR-T cells that were approved by FDA for the treatment of pediatric B-cell leukemia and refractory B-cell lymphoma.

Pulmonary mucosal immunity mediated through CpG provides adequate protection against pulmonary Mycobacterium tuberculosis infection in the mouse model. A role for type I interferon

Toll-Like Receptor (TLR) 9 stimulation is required for induction of potent immune responses against pathogen invasion. The use of unmethylated CpG as adjuvants in vaccines provides an excellent means of stimulating adaptive immunity. Our data demonstrate that CpG-C provided prolonged immune responses in the mouse model of tuberculosis when formulated with liposomes and the Mycobacterium tuberculosis antigen ESAT-6. A reduction in the mycobacterial burden was best achieved when administered as an intranasal vaccine and was dependent on type I interferon (IFN). There was a significant difference between CpG-C inoculated wild type and IFN-αR1^-/- mice, indicating that type I IFN plays a role in the immune response following CpG-C inoculation. Further analysis showed that early NK cell presence was not an absolute requirement, although elevated IFN-γ levels were detected in the lungs of mice within 48 h. The reduction in mycobacterial burden was MyD88-independent as CpG-C inoculated MyD88^-/- mice showed comparable mycobacterial burdens to wild type mice with no detriment due to the lack of MyD88. Together our data show that pulmonary stimulation of TLR9 bearing antigen presenting cells resulted in the induction of protective immunity against M. tuberculosis infection that was dependent on type I IFN signaling.

Clinical development of immunotherapies for HER2+ breast cancer: a review of HER2-directed monoclonal antibodies and beyond

Human epidermal growth factor receptor 2-positive (HER2⁺) breast cancer accounts for ~25% of breast cancer cases. Monoclonal antibodies (mAbs) against HER2 have led to unparalleled clinical benefit for a subset of patients with HER2⁺ breast cancer. In this narrative review, we summarize advances in the understanding of immune system interactions, examine clinical developments, and suggest rationales for future investigation of immunotherapies for HER2⁺ breast cancer. Complex interactions have been found between different branches of the immune system, HER2⁺ breast cancer, and targeted treatments (approved and under investigation). A new wave of immunotherapies, such as novel HER2-directed mAbs, antibody drug conjugates, vaccines, and adoptive T-cell therapies, are being studied in a broad population of patients with HER2-expressing tumors. The development of immunotherapies for HER2⁺ breast cancer represents an evolving field that should take into account interactions between different components of the immune system.

An Update on Anti-CD137 Antibodies in Immunotherapies for Cancer

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

Structure of the 4-1BB/4-1BBL complex and distinct binding and functional properties of utomilumab and urelumab

4-1BB (CD137, TNFRSF9) is an inducible costimulatory receptor expressed on activated T cells. Clinical trials of two agonist antibodies, utomilumab (PF-05082566) and urelumab (BMS-663513), are ongoing in multiple cancer indications, and both antibodies demonstrate distinct activities in the clinic. To understand these differences, we solved structures of the human 4-1BB/4-1BBL complex, the 4-1BBL trimer alone, and 4-1BB bound to utomilumab or urelumab. The 4-1BB/4-1BBL complex displays a unique interaction between receptor and ligand when compared with other TNF family members. Furthermore, our ligand-only structure differs from previously published data. Utomilumab, a ligand-blocking antibody, binds 4-1BB between CRDs 3 and 4. In contrast, urelumab binds 4-1BB CRD-1, away from the ligand binding site. Finally, cell-based assays demonstrate utomilumab is a milder agonist than urelumab. Collectively, our data provide a deeper understanding of the 4-1BB signaling complex, providing a template for future development of next generation 4-1BB targeted biologics.

Exploiting natural anti-tumor immunity for metastatic renal cell carcinoma

Clinical observations of spontaneous disease regression in some renal cell carcinoma (RCC) patients implicate a role for tumor immunity in controlling this disease. Puzzling, however, are findings that high levels of tumor infiltrating lymphocytes (TIL) are common to RCC. Despite expression of activation markers by TILs, functional impairment of innate and adaptive immune cells has been consistently demonstrated contributing to the failure of the immune system to control RCC. Immunotherapy can overcome the immunosuppressive effects of the tumor and provide an opportunity for long-term disease free survival. Unfortunately, complete response rates remain sub-optimal indicating the effectiveness of immunotherapy remains limited by tumor-specific factors and/or cell types that inhibit antitumor immune responses. Here we discuss immunotherapies and the function of multiple immune system components to achieve an effective response. Understanding these complex interactions is essential to rationally develop novel therapies capable of renewing the immune system's ability to respond to these tumors.

Neural Regulation of Pancreatic Cancer: A Novel Target for Intervention

The tumor microenvironment is known to play a pivotal role in driving cancer progression and governing response to therapy. This is of significance in pancreatic cancer where the unique pancreatic tumor microenvironment, characterized by its pronounced desmoplasia and fibrosis, drives early stages of tumor progression and dissemination, and contributes to its associated low survival rates. Several molecular factors that regulate interactions between pancreatic tumors and their surrounding stroma are beginning to be identified. Yet broader physiological factors that influence these interactions remain unclear. Here, we discuss a series of preclinical and mechanistic studies that highlight the important role chronic stress plays as a physiological regulator of neural-tumor interactions in driving the progression of pancreatic cancer. These studies propose several approaches to target stress signaling via the β-adrenergic signaling pathway in order to slow pancreatic tumor growth and metastasis. They also provide evidence to support the use of β-blockers as a novel therapeutic intervention to complement current clinical strategies to improve cancer outcome in patients with pancreatic cancer.

Boosting Cancer Immunotherapy with Anti-CD137 Antibody Therapy

In the past 5 years, immunomodulatory antibodies have revolutionized cancer immunotherapy. CD137, a member of the tumor necrosis factor receptor superfamily, represents a promising target for enhancing antitumor immune responses. CD137 helps regulate the activation of many immune cells, including CD4(+) T cells, CD8(+) T cells, dendritic cells, and natural killer cells. Recent studies indicate that the antitumor efficacy of therapeutic tumor-targeting antibodies can be augmented by the addition of agonistic antibodies targeting CD137. As ligation of CD137 provides a costimulatory signal in multiple immune cell subsets, combination therapy of CD137 antibody with therapeutic antibodies and/or vaccination has the potential to improve cancer treatment. Recently, clinical trials of combination therapies with agonistic anti-CD137 mAbs have been launched. In this review, we discuss the recent advances and clinical promise of agonistic anti-CD137 monoclonal antibody therapy.

The potential impact of mouse model selection in preclinical evaluation of cancer immunotherapy

This commentary provides the authors' perspective on the article "Routes of delivery for CpG and anti-CD137 for the treatment of orthotopic kidney tumors in mice", published in PLoS ONE. It also discusses the caveats of using subcutaneous tumors to model the treatment of human cancers versus orthotopic mouse models that more closely mimic human disease.