The importance of correctly timing cancer immunotherapy

A Partial Tumor Irradiation Approach for Complex Bulky Disease

A large proportion of cancer patients present with unresectable bulky disease at baseline or following treatment failure. The data available in the literature suggest that the vast majority of these patients do not benefit from available standard therapies. Therefore the clinical outcomes are poor; patients are desperate and usually relegated to palliative or best supportive care as the only options. Large tumor masses are usually hypoxic, resistant to radiation and systemic therapy, with extensive regional infiltration of the surrounding critical organs, the presence of which makes it impossible to deliver a radical dose of radiation. Promising data in terms of improved therapeutic ratio where such complex tumors are concerned can be seen with the use of new emerging unconventional radiotherapy techniques known as spatially fractionated radiotherapies (SFRT). One of them is PATHY, or PArtial Tumor irradiation targeting HYpoxic segment, which is characterized by a very short treatment course offering a large spectrum of therapeutic benefits in terms of the symptom relief, quality of life, local tumor control, neoadjuvant and immunomodulatory effects.

Establishing the applicability of cancer vaccines in combination with chemotherapeutic entities: current aspect and achievable prospects

Cancer immunotherapy is one of the recently developed cancer treatment modalities. When compared with conventional anticancer drug regimens, immunotherapy has shown significantly better outcomes in terms of quality of life and overall survival. It incorporates a wide range of immunomodulatory modalities that channel the effects of the immune system either by broadly modulating the host immune system or by accurately targeting distinct tumor antigens. One such treatment modality that has gained interest is cancer vaccine therapy which acts by developing antibodies against tumor cells. Cancer vaccines target individual peptides or groups of antigens that are released by tumor cells and presented by the APCs. This also initiates an effective process to activate the host immune responses. Studies on various types of cancer vaccines are conducted, out of which only few are approved by FDA for clinical uses. Despite of documented safety and efficacy of conventional chemotherapy and cancer vaccines, individually they did not produce substantial results in eradication of the cancer as a monotherapy. Hence, the combination approach holds the extensive potential to provide significant improvement in disease outcomes. Certain chemotherapy has immunomodulatory effects and is proven to synergize with cancer vaccines thereby enhancing their anti-tumor activities. Chemotherapeutic agents are known to have immunostimulatory mechanisms apart from its cytotoxic effect and intensify the anti-tumor activities of vaccines by various mechanisms. This review highlights various cancer vaccines, their mechanism, and how their activity gets affected by chemotherapeutic agents. It also aims at summarizing the evidence-based outcome of the combination approach of a cancer vaccine with chemotherapy and a brief on future aspects.

Toxoplasma gondii-derived antigen modifies tumor microenvironment of Ehrlich solid carcinoma murine model and enhances immunotherapeutic activity of cyclophosphamide

Pathogen-based cancer vaccine is a promising immunotherapeutic weapon to stimulate cancer immunosuppressive state. Toxoplasma gondii is a potent immunostimulant, and low-dose infection was linked to cancer resistance. Our goal was to evaluate the therapeutic antineoplastic activity of autoclaved Toxoplasma vaccine (ATV) against Ehrlich solid carcinoma (ESC) in mice in reference to and in combination with low-dose cyclophosphamide (CP), a cancer immunomodulator. Mice inoculation with ESC was followed by applying different treatment modalities including ATV, CP, and CP/ATV. We evaluated the impact of the different treatments on liver enzymes and pathology, tumor weight, volume, and histopathological changes. Using immunohistochemistry, we evaluated CD8⁺ T cell, FOXP3⁺ Treg, CD8⁺/Treg outside and inside ESC, and angiogenesis. Results showed significant tumor weights and volumes reduction with all treatments with 13.3% inhibition of tumor development upon combined CP/ATV use. Significant necrosis and fibrosis were noted in ESC by all treatments with improved hepatic functions versus non-treated control. Although ATV was almost equivalent to CP in tumor gross and histopathology, it promoted an immunostimulatory activity with significant Treg cells depletion outside ESC and CD8⁺ T cells infiltration inside ESC with higher CD8⁺ T/Treg ratio inside ESC superior to CP. Combined with CP, ATV exhibited significant synergistic immunotherapeutic and antiangiogenic action compared to either treatment alone with significant Kupffer cells hyperplasia and hypertrophy. Exclusively, therapeutic antineoplastic and antiangiogenic activity of ATV against ESC was verified that boosted CP immunomodulatory action which highlights a novel biological cancer immunotherapeutic vaccine candidate.

Challenges in neoantigen-directed therapeutics

A fundamental prerequisite for the efficacy of cancer immunotherapy is the presence of functional, antigen-specific T cells within the tumor. Neoantigen-directed therapy is a promising strategy that aims at targeting the host's immune response against tumor-specific antigens, thereby eradicating cancer cells. Initial forays have been made in clinical environments utilizing vaccines and adoptive cell therapy; however, many challenges lie ahead. We provide an in-depth overview of the current state of the field with an emphasis on in silico neoantigen discovery and the clinical aspects that need to be addressed to unlock the full potential of this therapy.

Bladder Cancer Extracellular Vesicles Elicit a CD8 T Cell-Mediated Antitumor Immunity

Tumor-derived extracellular vesicles (TEVs) play crucial roles in mediating immune responses, as they carry and present functional MHC-peptide complexes that enable them to modulate antigen-specific CD8⁺ T-cell responses. However, the therapeutic potential and immunogenicity of TEV-based therapies against bladder cancer (BC) have not yet been tested. Here, we demonstrated that priming with immunogenic Extracellular Vesicles (EVs) derived from murine MB49 BC cells was sufficient to prevent MB49 tumor growth in mice. Importantly, antibody-mediated CD8⁺ T-cell depletion diminished the protective effect of MB49 EVs, suggesting that MB49 EVs elicit cytotoxic CD8⁺ T-cell-mediated protection against MB49 tumor growth. Such antitumor activity may be augmented by TEV-enhanced immune cell infiltration into the tumors. Interestingly, MB49 EV priming was unable to completely prevent, but significantly delayed, unrelated syngeneic murine colon MC-38 tumor growth. Cytokine array analyses revealed that MB49 EVs were enriched with pro-inflammatory factors that might contribute to increasing tumor-infiltrating immune cells in EV-primed MC-38 tumors. These results support the potential application of TEVs in personalized medicine, and open new avenues for the development of adjuvant therapies based on patient-derived EVs aimed at preventing disease progression.

Modeling codelivery of CD73 inhibitor and dendritic cell-based vaccines in cancer immunotherapy

Dendritic cells (DCs) are the dominant class of antigen-presenting cells in humans; therefore, a range of DC-based approaches have been established to promote an immune response against cancer cells. The efficacy of DC-based immunotherapeutic approaches is markedly affected by the immunosuppressive factors related to the tumor microenvironment, such as adenosine. In this paper, based on immunological theories and experimental data, a hybrid model is designed that offers some insights into the effects of DC-based immunotherapy combined with adenosine inhibition. The model combines an individual-based model for describing tumor-immune system interactions with a set of ordinary differential equations for adenosine modeling. Computational simulations of the proposed model clarify the conditions for the onset of a successful immune response against cancer cells. Global and local sensitivity analysis of the model highlights the importance of adenosine blockage for strengthening effector cells. The model is used to determine the most effective suppressive mechanism caused by adenosine, proper vaccination time, and the appropriate time interval between injections.

Biopolymer Immune Implants' Sequential Activation of Innate and Adaptive Immunity for Colorectal Cancer Postoperative Immunotherapy

Surgical resection is the first-line therapy for colorectal cancer (CRC). However, for advanced CRC, the curative effect of surgical resection is limited due to either local recurrence or distal metastasis. Postoperative in situ immunotherapy, presents a promising option for preventing tumor recurrence and metastasis, owing to the fact that surgeons have unique opportunities and direct access to the surgical site. Herein, a designed biopolymer immune implant for CRC post-surgical therapy, characterized with tissue adhesion, sustained drug release, and sequential elicitation of innate immunity, adaptive immunity, and immune memory effects, is reported. With gradual release of the loaded resiquimod (R848) and anti-OX40 antibody (aOX40), the immune implant can eradicate residual tumors post-surgery (with no tumor recurrence in 150 days), inhibit the growth of distal tumors and elicit immune memory effects to resist tumor re-challenge. Immunological analysis reveal that the biopolymer immune plant treatment leads to a two-stage action, with enhanced natural killer cells (NK cells) infiltration and activation of dendritic cells (DCs) in the first several days, then a greatly increased population of infiltrating T cells, and finally immune memory effects are established. The reported biopolymer immune implants provide a valuable and clinically-relevant option for post-surgical CRC management.

Demethoxycurcumin Inhibits In Vivo Growth of Xenograft Tumors of Human Cervical Cancer Cells

BACKGROUND/AIM

Demethoxycurcumin (DMC), a derivate of curcumin from natural plants, exerts antitumor effects on various human cancer cells in vitro and in vivo. Nevertheless, no reports have disclosed whether DMC can affect the growth of human cervical cancer cells in vivo. Therefore we investigated the antitumor effects of DMC on a HeLa cell xenograft model in nude mice in this study.

MATERIALS AND METHODS

Twenty-four nude mice were subcutaneously injected with HeLa cells. All mice were randomly divided into control, low-dose DMC (30 mg/kg), and high-dose DMC (50 mg/kg) groups and individual mice were treated intraperitoneally accordingly every 2 days.

RESULTS

DMC significantly reduced tumor weights and volumes of HeLa cell xenografts in mice, indicating the suppression of growth of xenograft tumors.

CONCLUSION

These effects and findings might provide evidence for investigating the potential use of DMC as an anti-cervical cancer drug in the future.

Encapsulated Checkpoint Blocker Before Chemotherapy: The Optimal Sequence of Anti-CTLA-4 and Doxil Combination Therapy

INTRODUCTION

Today, a new paradigm has emerged for cancer treatment introducing combination therapies. Doxil, a liposomal doxorubicin serving as a chemotherapeutic agent, is an effective immunogenic killer of cancer cells. Anti-CTLA-4 has been approved for the treatment of some cancers, including melanoma, but side effects have limited its therapeutic potential.

METHODS

In this study, two approaches were utilized to increase treatment efficiency and decrease the side effects of anti-CTLA-4, combining it with chemotherapy and encapsulation in a PEGylated liposome. A different sequence of anti-CTLA-4 and Doxil was assessed in combination therapy using non-liposomal and liposomal anti-CTLA-4.

RESULTS

Our results showed that liposomal anti-CTLA-4 reduced the size of established tumors and increased survival in comparison with non-liposomal anti-CTLA-4 in a well-established B16 mouse melanoma model. In combination therapy with Doxil, only the administration of anti-CTLA-4 before Doxil showed synergism in both non-liposomal and liposomal form and increased the CD8+/regulatory T cell ratio.

DISCUSSION

In summary, our results demonstrate the potential of utilizing a nanocarrier system for the delivery of checkpoint blockers, such as anti-CTLA-4 which further showed potential in a combination therapy, especially when administered before chemotherapy.

The future of radiation-induced abscopal response: beyond conventional radiotherapy approaches

Advances in the immunological pharmaceuticals, such as checkpoint inhibitors and agonists, have positive implications for the future of the radiotherapy abscopal response. A once rare phenomenon, whereby distant nonirradiated tumor sites regressed after radiotherapy alone, may become more common when combined with the immune modulating agents. Radiotherapy can increase neoantigen expression, increased tumor PD-L1 expression, increase MHC class I expression, reverse exhausted CD8 T cells and increase tumor-infiltrating tumors within the tumor microenvironment. These changes in the tumor and the tumor microenvironment after radiotherapy could potentiate responses to anti-CTL-4, anti-PD-L1/PD-1 and other immunotherapy agents. Thus, advances in checkpoint inhibitors have increased interest in re-evaluation of the role of conventional radiotherapy approaches on the immune system. We reviewed newer nonconventional approaches such as SBRT-PATHY, GRID, FLASH, carbon ion and proton therapy and their role in eliciting immune responses. We believe that combining these novel radiation methods may enhance the outcome with the newly US FDA approved immune modulating agents.

Time-synchronized immune-guided SBRT partial bulky tumor irradiation targeting hypoxic segment while sparing the peritumoral immune microenvironment

Background

A novel unconventional SBRT-based PArtial Tumor irradiation targeting HYpoxic clonogenic cells (SBRT-PATHY) for induction of the tumoricidal bystander (BE) and abscopal effects (AE) was developed by translating our preclinical findings to a clinic in 2016. In order to further improve BE/AE response rate, SBRT-PATHY was upgraded in 2018 by the sparing of peritumoral immune microenvironment as a new OAR, defined by its own dose-constraints. Considering the anti-tumor immune response homeostatic fluctuation, which is cyclically suppressed and incited (“switched off and on”), we synchronized SBRT-PATHY with its most excitable phase, in order to overcome tumor tolerance locally and systemically. The aim of this study, therefore, was to report on the initial results of our latest innovation aimed to further improve BE/AE response rate by testing the effectiveness of the time-synchronized immune-guided SBRT-PATHY.

Materials and methods

In order to serially map the homeostatic anti-tumor immune response-fluctuations, High Sensitive C-Reactive Protein (HS-CRP), Lactate Dehydrogenase (LDH) and Lymphocyte/Monocyte Ratio (LMR) were analyzed using high-order polynomial trend analysis as surrogate of immune system response. After the biomarker data analysis detected the immune fluctuations and related idiosyncratic immune cycle periodicity, we determined the “most favourable” and “least favourable” treatment time-positions in the immune cycle. In order to evaluate the impact of an idiosyncratic immune cycle on treatment outcomes, our first consecutive four patients were treated on the “most favourable” while the remaining four on the “least favourable” day.

Results

The median follow-up was 11.8 months. The biomarker data analysis showed periodic immune response fluctuations of regular frequency. The “right” synchronization of SBRT-PATHY with the “most favorable day” of anti-tumor immune response was accompanied with improved clinical outcomes in terms of BE/AE-response rate.

Conclusion

We believe the right synchronization of radiotherapy with the homeostatically oscillating immune response may improve the probability of inducing BE/AE.

Present study has been retrospectively registered on 18th of October 2019 by the ethic committee for Austrian region „Kärnten “in Klagenfurt (AUT), under study number A 37/19.

Targeting of the Cancer-Associated Fibroblast-T-Cell Axis in Solid Malignancies

The introduction of a wide range of immunotherapies in clinical practice has revolutionized the treatment of cancer in the last decade. The majority of these therapeutic modalities are centered on reinvigorating a tumor-reactive cytotoxic T-cell response. While impressive clinical successes are obtained, the majority of cancer patients still fail to show a clinical response, despite the fact that their tumors express antigens that can be recognized by the immune system. This is due to a series of other cellular actors, present in or attracted towards the tumor microenvironment, including regulatory T-cells, myeloid-derived suppressor cells and cancer-associated fibroblasts (CAFs). As the main cellular constituent of the tumor-associated stroma, CAFs form a heterogeneous group of cells which can drive cancer cell invasion but can also impair the migration and activation of T-cells through direct and indirect mechanisms. This singles CAFs out as an important next target for further optimization of T-cell based immunotherapies. Here, we review the recent literature on the role of CAFs in orchestrating T-cell activation and migration within the tumor microenvironment and discuss potential avenues for targeting the interactions between fibroblasts and T-cells.

Tumor Microenvironment as A "Game Changer" in Cancer Radiotherapy

Radiotherapy (RT), besides cancer cells, also affects the tumor microenvironment (TME): tumor blood vessels and cells of the immune system. It damages endothelial cells and causes radiation-induced inflammation. Damaged vessels inhibit the infiltration of CD8+ T lymphocytes into tumors, and immunosuppressive pathways are activated. They lead to the accumulation of radioresistant suppressor cells, including tumor-associated macrophages (TAMs) with the M2 phenotype, myeloid-derived suppressor cells (MDSCs), and regulatory T cells (Tregs). The area of tumor hypoxia increases. Hypoxia reduces oxygen-dependent DNA damage and weakens the anti-cancer RT effect. It activates the formation of new blood vessels and leads to cancer relapse after irradiation. Irradiation may also activate the immune response through immunogenic cell death induction. This leads to the "in situ" vaccination effect. In this article, we review how changes in the TME affect radiation-induced anticancer efficacy. There is a very delicate balance between the activation of the immune system and the immunosuppression induced by RT. The effects of RT doses on immune system reactions and also on tumor vascularization remain unclear. A better understanding of these interactions will contribute to the optimization of RT treatment, which may prevent the recurrence of cancer.

Combination of 2 Bioactive Compounds for Treatment of Breast Cancer: Triterpenoid Cucurbitacin I and Phenolic CAPE

It has been demonstrated that both cucurbitacin I (Cu I) and caffeic acid phenethyl ester (CAPE) have anticancer activities. The current study aimed to examine the proliferation, migration, and colony formation actions of Cu I and CAPE on MCF-7 and MDA-MB-231 human breast cancer cells. The antimigration, antiproliferative, and colony inhibition effects of different dosages of Cu I, CAPE, and Cu I + CAPE on cells were determined by the 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) cell viability assay, wound healing, and colony formation assays, respectively. Compared with single treatment, combination of 2 bioactive compounds enhanced the anticancer activity. When Cu I and CAPE were combined, a strong inhibitor effect was shown on cell growth, colony formation, and cell migration compared with the compounds used singly. The concomitant treatment with Cu I and CAPE showed stronger antiproliferative activities on both MCF-7 and MDA-MB-231 cells compared with individual treatment with either Cu I or CAPE. Caffeic acid phenethyl ester is a specific inhibitor of Nuclear factor-kappa B (NF-κB). It shows anticancer activity depending on this inhibition. It is a bioactive phenolic compound that is derived from propolis. Cucurbitacin I is a selective Januskinase/signal transducer and a transcription-3 signal pathway inhibitor. Combination of these 2 natural anticancer compounds is beneficial in the treatment of cancer, as well as the side effects associated with classical chemotherapeutics not being observed with the use of these compounds.

Radiation therapy and immunotherapy: what is the optimal timing or sequencing?

Radiotherapy is a component of the standard of care for many patients with locally advanced nonmetastatic tumors and increasingly those with oligometastatic tumors. Despite encouraging advances in local control and progression-free and overall survival outcomes, continued manifestation of tumor progression or recurrence leaves room for improvement in therapeutic efficacy. Novel combinations of radiation with immunotherapy have shown promise in improving outcomes and reducing recurrences by overcoming tumor immune tolerance and evasion mechanisms via boosting the immune system's ability to recognize and eradicate tumor cells. In this review, we discuss preclinical and early clinical evidence that radiotherapy and immunotherapy can improve treatment outcomes for locally advanced and metastatic tumors, elucidate underlying molecular mechanisms and address strategies to optimize timing and sequencing of combination therapy for maximal synergy.

Microparticle Depots for Controlled and Sustained Release of Endosomolytic Nanoparticles

Introduction

Nucleic acids have gained recognition as promising immunomodulatory therapeutics. However, their potential is limited by several drug delivery barriers, and there is a need for technologies that enhance intracellular delivery of nucleic acid drugs. Furthermore, controlled and sustained release is a significant concern, as the kinetics and localization of immunomodulators can influence resultant immune responses. Here, we describe the design and initial evaluation of poly(lactic-co-glycolic) acid (PLGA) microparticle (MP) depots for enhanced retention and sustained release of endosomolytic nanoparticles that enable the cytosolic delivery of nucleic acids.

Methods

Endosomolytic p[DMAEMA]_10kD-bl-[PAA_0.3-co-DMAEMA_0.3-co-BMA_0.4]_25kD diblock copolymers were synthesized by reversible addition-fragmentation chain transfer polymerization. Polymers were electrostatically complexed with nucleic acids and resultant nanoparticles (NPs) were encapsulated in PLGA MPs. To modulate release kinetics, ammonium bicarbonate was added as a porogen. Release profiles were quantified in vitro and in vivo via quantification of fluorescently-labeled nucleic acid. Bioactivity of released NPs was assessed using small interfering RNA (siRNA) targeting luciferase as a representative nucleic acid cargo. MPs were incubated with luciferase-expressing 4T1 (4T1-LUC) breast cancer cells in vitro or administered intratumorally to 4T1-LUC breast tumors, and silencing via RNA interference was quantified via longitudinal luminescence imaging.

Results

Endosomolytic NPs complexed to siRNA were effectively loaded into PLGA MPs and release kinetics could be modulated in vitro and in vivo via control of MP porosity, with porous MPs exhibiting faster cargo release. In vitro, release of NPs from porous MP depots enabled sustained luciferase knockdown in 4T1 breast cancer cells over a five-day treatment period. Administered intratumorally, MPs prolonged the retention of nucleic acid within the injected tumor, resulting in enhanced and sustained silencing of luciferase relative to a single bolus administration of NPs at an equivalent dose.

Conclusion

This work highlights the potential of PLGA MP depots as a platform for local release of endosomolytic polymer NPs that enhance the cytosolic delivery of nucleic acid therapeutics.

Enhancing Dendritic Cell Therapy in Solid Tumors with Immunomodulating Conventional Treatment

Dendritic cells (DCs) are the most potent antigen-presenting cells and are the key initiator of tumor-specific immune responses. These characteristics are exploited by DC therapy, where DCs are ex vivo loaded with tumor-associated antigens (TAAs) and used to induce tumor-specific immune responses. Unfortunately, clinical responses remain limited to a proportion of the patients. Tumor characteristics and the immunosuppressive tumor microenvironment (TME) of the tumor are likely hampering efficacy of DC therapy. Therefore, reducing the immunosuppressive TME by combining DC therapy with other treatments could be a promising strategy. Initially, conventional cancer therapies, such as chemotherapy and radiotherapy, were thought to specifically target cancerous cells. Recent insights indicate that these therapies additionally augment tumor immunity by targeting immunosuppressive cell subsets in the TME, inducing immunogenic cell death (ICD), or blocking inhibitory molecules. Therefore, combining DC therapy with registered therapies such as chemotherapy, radiotherapy, or checkpoint inhibitors could be a promising treatment strategy to improve the efficacy of DC therapy. In this review, we evaluate various clinical applicable combination strategies to improve the efficacy of DC therapy.

Therapeutic Cancer Vaccine and Combinations With Antiangiogenic Therapies and Immune Checkpoint Blockade

Considering the high importance of immune surveillance and immune escape in the evolution of cancer, the development of immunotherapeutic strategies has become a major field of research in recent decades. The considerable therapeutic breakthrough observed when targeting inhibitory immune checkpoint molecules has highlighted the need to find approaches enabling the induction and proper activation of an immune response against cancer. In this context, therapeutic vaccination, which can induce a specific immune response against tumor antigens, is an important approach to consider. However, this strategy has its advantages and limits. Considering its low clinical efficacy, approaches combining therapeutic cancer vaccine strategies with other immunotherapies or targeted therapies have been emphasized. This review will list different cancer vaccines, with an emphasis on their targets. We highlight the results and limits of vaccine strategies and then describe strategies that combine therapeutic vaccines and antiangiogenic therapies or immune checkpoint blockade. Antiangiogenic therapies and immune checkpoint blockade are of proven clinical efficacy for some indications, but are limited by toxicity and the development of resistance. Their combination with therapeutic vaccines could be a way to improve therapeutic outcome by specifically stimulating the immune system and considering a global approach to tumor microenvironment remodeling.

Combination Strategies to Optimize Efficacy of Dendritic Cell-Based Immunotherapy

Dendritic cells (DCs) are antigen-presenting cells (APCs) that are essential for the activation of immune responses. In various malignancies, these immunostimulatory properties are exploited by DC-therapy, aiming at the induction of effective anti-tumor immunity by vaccination with ex vivo antigen-loaded DCs. Depending on the type of DC-therapy used, long-term clinical efficacy upon DC-therapy remains restricted to a proportion of patients, likely due to lack of immunogenicity of tumor cells, presence of a stromal compartment, and the suppressive tumor microenvironment (TME), thereby leading to the development of resistance. In order to circumvent tumor-induced suppressive mechanisms and unleash the full potential of DC-therapy, considerable efforts have been made to combine DC-therapy with chemotherapy, radiotherapy or with checkpoint inhibitors. These combination strategies could enhance tumor immunogenicity, stimulate endogenous DCs following immunogenic cell death, improve infiltration of cytotoxic T lymphocytes (CTLs) or specifically deplete immunosuppressive cells in the TME, such as regulatory T-cells and myeloid-derived suppressor cells. In this review, different strategies of combining DC-therapy with immunomodulatory treatments will be discussed. These strategies and insights will improve and guide DC-based combination immunotherapies with the aim of further improving patient prognosis and care.

Experimental Combined Immunotherapy of Tumours with Major Histocompatibility Complex Class I Downregulation

Combined immunotherapy constitutes a novel, advanced strategy in cancer treatment. In this study, we investigated immunotherapy in the mouse TC-1/A9 model of human papillomavirus type 16 (HPV16)-associated tumors characterized by major histocompatibility complex class I (MHC-I) downregulation. We found that the induction of a significant anti-tumor response required a combination of DNA vaccination with the administration of an adjuvant, either the synthetic oligodeoxynucleotide ODN1826, carrying immunostimulatory CpG motifs, or α-galactosylceramide (α-GalCer). The most profound anti-tumor effect was achieved when these adjuvants were applied in a mix with a one-week delay relative to DNA immunization. Combined immunotherapy induced tumor infiltration with various subsets of immune cells contributing to tumor regression, of which cluster of differentiation (CD) 8⁺ T cells were the predominant subpopulation. In contrast, the numbers of tumor-associated macrophages (TAMs) were not markedly increased after immunotherapy but in vivo and in vitro results showed that they could be repolarized to an anti-tumor M1 phenotype. A blockade of T cell immunoglobulin and mucin-domain containing-3 (Tim-3) immune checkpoint had a negligible effect on anti-tumor immunity and TAMs repolarization. Our results demonstrate a benefit of combined immunotherapy comprising the activation of both adaptive and innate immunity in the treatment of tumors with reduced MHC-I expression.

Implantable Synthetic Immune Niche for Spatiotemporal Modulation of Tumor-Derived Immunosuppression and Systemic Antitumor Immunity: Postoperative Immunotherapy

The development of biomaterial-based immune niches that can modulate immunosuppressive factors in tumor microenvironment (TME) will be a key technology for improving current cancer immunotherapy. Here, implantable, engineered 3D porous scaffolds are designed to generate synergistic action between myeloid-derived suppressor cell (MDSC)-depleting agents, which can accommodate the establishment of a permissive immunogenic microenvironment to counteract tumor-induced immunosuppression, and cancer vaccines consisting of whole tumor lysates and nanogel-based adjuvants, which can generate tumor antigen-specific T cell responses. The local peritumoral implantation of the synthetic immune niche (termed immuneCare-DISC, iCD) as a postsurgical treatment in an advanced-stage primary 4T1 breast tumor model generates systemic antitumor immunity and prevents tumor recurrence at the surgical site as well as the migration of residual tumor cells into the lungs, resulting in 100% survival. These therapeutic outcomes are achieved through the inhibition of immunosuppressive MDSCs in tumors and spleens by releasing gemcitabine and recruitment/activation of dendritic cells, enhanced population of CD4⁺ and CD8⁺ T cells, and increased IFN-γ production by cancer vaccines from the iCD. This combined spatiotemporal modulation of tumor-derived immunosuppression and vaccine-induced immune stimulation through the iCD is expected to provide an immune niche for prevention of postoperative tumor recurrence and metastasis.

ICOS activation in combination with electrochemotherapy generates effective anti-cancer immunological responses in murine models of primary, secondary and metastatic disease

Electrochemotherapy is an evolving therapy which has recently been shown to induce an immunogenic form of cell death. It is hypothesized that the immunogenic cell death induced by electrochemotherapy may compliment the responses seen with anti-cancer immunotherapies. We therefore examined the effect of electrochemotherapy in combination with ICOS activation, which promotes the activity of previously activated T cells. In comparison to either monotherapy which resulted in no curative outcomes in any model, in a CT26 primary tumour 50% of mice were cured, with 100% of cured mice surviving tumour rechallenge. In a dual flank CT26 model mimicking secondary disease 20% of mice were cured, and 30% of mice were cured using an aggressively metastatic Lewis Lung Carcinoma model. We have shown the novel combination of electrochemotherapy with ICOS activation can inhibit local and distal tumour growth, including total tumour clearance with long lasting immunological memory.

Tackling immunomonitoring in gastrointestinal cancer

PURPOSE OF REVIEW

The growing awareness that the immune system is a key player in the antitumoral response and the excellent clinical results achieved in some settings with anti-programmed cell death 1 (PD1)/programmed death ligand 1 (PDL1) and anti-cytotoxic T-lymphocyte-associated protein 4 (CTLA4) drugs has led to the rise of immunotherapy as a supplement or an alternative to conventional cancer treatment. The high costs associated with these therapies, their significant toxicity and the need to understand and circumvent immune escape mechanisms raise the urgent need for immunological assessment of therapy response. The study of the immunological parameters before, during and after treatment is referred to as immunomonitoring. This review discusses the current knowledge of immunomonitoring markers in gastrointestinal cancers.

RECENT FINDINGS

The last decade has seen a collaborative effort to standardize the assays performed in clinical trials to assess response to immunotherapy. Since then, multiple studies have been conducted on blood samples, biopsies and surgical specimens to determine their immunological profiles leading to the identification of several immunological markers possessing a predictive value of response to treatment.

SUMMARY

Future research will focus on detangling the predictive value of immune markers in different therapeutic models, and also to develop new noninvasive means to monitor the immune response of patients. VIDEO ABSTRACT: http://links.lww.com/COON/A20.