Enhancing the potency of a whole-cell breast cancer vaccine in mice with an antibody-IL-2 immunocytokine that targets exposed phosphatidylserine

Proteomic and lipidomic analysis of low-density lipoprotein identifies potential biomarkers of early estrogen receptor-positive breast cancer

Estrogen receptor (ER)-positive breast cancer (BC) is a prevalent and fatal cancer among women, and there is a need to identify molecules involved in the disease pathophysiology which could also serve as biomarkers for early detection. Detection of cancer markers in whole plasma produces excessive information, and identifying important markers involved in cancer progression is challenging. We identified a BC-specific low-density lipoprotein (LDL) particle isolated by ultracentrifugation from the plasma of ER-positive BC patients. This LDL has an aberrant proteome and lipidome, significantly different from that of LDL from healthy women, including a high association with the pro-tumor chemokines CXCL4 and CXCL7, and an enrichment with the lipid subclasses phosphatidylethanolamine, ceramide, triglycerides, lysophosphatidylcholine, phosphatidylserine, phosphatidic acid, and sphingomyelin. In contrast, phosphatidylinositol species were significantly less abundant in LDL from tumor patients than in control. Moreover, BC-associated LDL has a distinct effect on macrophage phenotype, inducing an increased gene expression of IL1β, IL8 and CD206 and decreased gene expression of TNFα, a gene signature characteristic of tumor-associated macrophages (TAMs). This suggests that this formerly unrecognized form of LDL may represent LDL particles that are recruited by the tumor microenvironment to support tumor progression by inducing discrete subsets of TAMs. In conclusion, these data offer BC-associated LDL as an early biomarker detection platform for ER-positive BC. Furthermore, LDL-associated proteins and lipids that promote BC progression may also serve in the future as novel targets for BC therapies.

Pairing tumor cell vesicle antigens with cationic nano-adjuvants by electrostatic adherence for personalized cancer vaccine

Simultaneous co-delivery of both antigens and adjuvants is crucial for the efficient activation of dendritic cells (DCs), but it has often been overlooked in the context of tumor cell-based vaccines. Building on the significant advancements in cationic nano-adjuvants, we proposed a straightforward and effective strategy for crafting personalized cancer vaccines, in which tumor cell vesicle antigens were paired with cationic nano-adjuvants to form nano-network through electrostatic adherence. Our pioneering research indicates that densely arranged nanoparticles can be simultaneously taken up by DCs, thus facilitating the co-delivery of adjuvants and antigens. To further enhance the interaction between DCs and antigens, the antigens-adjuvants nano-network was reconstructed using high aspect ratio silicon dioxide (SiO2) rods to generate 3D structures with ample interparticle spaces. This fosters a conducive environment for DCs infiltration, thereby optimizing the spatial and temporal orchestration of antigen cross-presentation. When combined with programmed death ligand 1 (PD-L1) immune checkpoint inhibitors, the dual-scale cancer vaccine effectively inhibits tumor proliferation through T cell-mediated mechanisms, resulting in a survival rate of 60 % in mice for over 40 days. In summary, our study introduces an innovative approach to the spatiotemporal orchestration of antigen cross-presentation, providing fresh insights into the construction of cancer vaccines based on tumor cells.

Phosphatidylserine (PS)-targeting chimeric Interferon (IFN) fusion proteins for anti-tumor applications

In viable healthy cells, membrane phospholipids are asymmetrically distributed across the lipid bilayer, whereby the anionic phospholipid phosphatidylserine is virtually all distributed on the inner leaflet of the plasma membrane. During apoptosis, phospholipid asymmetry collapses and PS is externalized to the external leaflet where it serves as an "eat-me" signal for efferocytosis, the process whereby dying cells are engulfed and degraded by phagocytes. PS is also externalized on viable activated tumor endothelial cells, stromal cells and cancer cells in the tumor microenvironment reflecting a pathophysiological state of solid cancers that function to suppress host anti-tumor immunity. Several strategies have been envisioned to target dysregulated PS in the tumor microenvironment including PS binding proteins such as Annexin V and PS-targeting monoclonal antibodies (Bavituximab) with promising preclinical results. Here, in an attempt to enhance the efficacy of PS-targeting therapeutics, we have generated a series of recombinant chimeric fusion proteins that fuse type I and type III IFNs (IFN-β-IFN-λ) into a single polypeptide chain separated by a short linker. The IFN-β-IFN-λ fusion proteins retain functions of both type I and type III IFNs but show combined effects to improve biological function as well as enhance anti-tumor activities. To localize IFNs to sites of externalized PS, we next fused the IFN-β-IFN-λ chimeric protein to the PS-targeting gamma-carboxyglutamic acid-rich (Gla) domain of Growth Arrest Specific factor 6 (Gas-6), rendering these IFN biologics as PS targeting modalities. Gas6-IFN-β-IFN-λ proteins selectively bind PS as evident by solid-phase ELISA assays as well as bind PS-positive cells, including apoptotic cells and cells that express CDC50 subunit mutant of the ATP11C flippase. In vivo, Gas6-IFN-β-IFN-λ retain strong anti-tumor activities in a syngeneic model when expressed ectopically in a E0771 breast cancer model and B16-F10 melanoma models. Collectively, we report on the generation and utility of a series of novel in class IFN fusion proteins that target the immune stimulatory features of IFNs to the PS externalization in the tumor microenvironment.

Implications of glycosylation for the development of selected cytokines and their derivatives for medical use

Cytokines are important regulators of immune responses, making them attractive targets for autoimmune diseases and cancer therapeutics. Yet, the significance of cytokine glycosylation remains underestimated. Many cytokines carry N- and O-glycans and some even undergo C-mannosylation. Recombinant cytokines produced in heterologous host cells may lack glycans or exhibit a different glycosylation pattern such as varying levels of galactosylation, sialylation, fucosylation or xylose addition compared to their human counterparts, potentially impacting critical immune interactions. We focused on cytokines that are currently utilized or designed in advanced therapeutic formats, including immunocytokines, fusokines, engager cytokines, and genetically engineered 'supercytokines.' Despite the innovative designs of these cytokine derivatives, their glycosylation patterns have not been extensively studied. By examining the glycosylation of the human native cytokines, G-CSF and GM-CSF, interferons β and γ, TNF-α and interleukins-2, -3 -4, -6, -7, -9, -12, -13, -15, -17A, -21, and - 22, we aim to assess its potential impact on their therapeutic derivatives. Understanding the glycosylation of the native cytokines could provide critical insights into the safety, efficacy, and functionality of these next-generation cytokine therapies, affecting factors such as stability, bioactivity, antigenicity, and half-life. This knowledge can guide the choice of optimal expression hosts for production and advance the development of effective cytokine-based therapeutics and synthetic immunology drugs.

Engineered mitochondria exert potent antitumor immunity as a cancer vaccine platform

The preferable antigen delivery profile accompanied by sufficient adjuvants favors vaccine efficiency. Mitochondria, which feature prokaryotic characteristics and contain various damage-associated molecular patterns (DAMPs), are easily taken up by phagocytes and simultaneously activate innate immunity. In the current study, we established a mitochondria engineering platform for generating antigen-enriched mitochondria as cancer vaccine. Ovalbumin (OVA) and tyrosinase-related protein 2 (TRP2) were used as model antigens to synthesize fusion proteins with mitochondria-localized signal peptides. The lentiviral infection system was then employed to produce mitochondrial vaccines containing either OVA or TRP2. Engineered OVA- and TRP2-containing mitochondria (OVA-MITO and TRP2-MITO) were extracted and evaluated as potential cancer vaccines. Impressively, the engineered mitochondria vaccine demonstrated efficient antitumor effects when used as both prophylactic and therapeutic vaccines in murine tumor models. Mechanistically, OVA-MITO and TRP2-MITO potently recruited and activated dendritic cells (DCs) and induced a tumor-specific cell-mediated immunity. Moreover, DC activation by mitochondria vaccine critically involves TLR2 pathway and its lipid agonist, namely, cardiolipin derived from the mitochondrial membrane. The results demonstrated that engineered mitochondria are natively well-orchestrated carriers full of immune stimulants for antigen delivery, which could preferably target local dendritic cells and exert strong adaptive cellular immunity. This proof-of-concept study established a universal platform for vaccine construction with engineered mitochondria bearing alterable antigens for cancers as well as other diseases.

Stimulating the Antitumor Immune Response Using Immunocytokines: A Preclinical and Clinical Overview

Cytokines are immune modulators which can enhance the immune response and have been proven to be an effective class of immunotherapy. Nevertheless, the clinical use of cytokines in cancer treatment has faced several challenges associated with poor pharmacokinetic properties and the occurrence of adverse effects. Immunocytokines (ICKs) have emerged as a promising approach to overcome the pharmacological limitations observed with cytokines. ICKs are fusion proteins designed to deliver cytokines in the tumor microenvironment by taking advantage of the stability and specificity of immunoglobulin-based scaffolds. Several technological approaches have been developed. This review focuses on ICKs designed with the most impactful cytokines in the cancer field: IL-2, TNFα, IL-10, IL-12, IL-15, IL-21, IFNγ, GM-CSF, and IFNα. An overview of the pharmacological effects of the naked cytokines and ICKs tested for cancer therapy is detailed. A particular emphasis is given on the immunomodulatory effects of ICKs associated with their technological design. In conclusion, this review highlights active ways of development of ICKs. Their already promising results observed in clinical trials are likely to be improved with the advances in targeting technologies such as cytokine/linker engineering and the design of multispecific antibodies with tumor targeting and immunostimulatory functional properties.

MHY1485 potentiates immunogenic cell death induction and anti-cancer immunity following irradiation

Recent in vitro experiments showed that combined treatment with MHY1485, a low-molecular-weight compound, and X-ray irradiation significantly increased apoptosis and senescence in tumor cells, which was associated with oxidative stress, endoplasmic reticulum (ER) stress and p21 stabilization, compared to radiation treatment alone. However, evidence for MHY1485 treatment-mediated suppression of tumor growth in animals is still lacking. Furthermore, it has been shown that ER stress enhances immunogenic cell death (ICD) in tumor cells, as it can exert a favorable influence on the anti-cancer immune system. In the present study, we examined whether co-treatment of MHY1485 and X-ray irradiation induces ICD and in vivo tumor growth suppression using the CT26 and Lewis lung carcinoma murine tumor cell lines. We found that MHY1485 + X-ray treatment promotes ICD more effectively than X-ray treatment alone. MHY1485 suppresses tumor growth in vivo under co-treatment with X-rays and increases INF-γ, tumor necrosis factor, interleukin-2 and interleukin-12 levels in the spleen as well as the presence of CD8+ cells in the tumor. The results suggest that MHY1485 treatment leads to the conversion of irradiated tumors into effective vaccines. Thus, MHY1485 is a promising lead compound for use in combination with radiotherapy.

Bidirectional crosstalk between therapeutic cancer vaccines and the tumor microenvironment: Beyond tumor antigens

Immunotherapy has rejuvenated cancer therapy, especially after anti-PD-(L)1 came onto the scene. Among the many therapeutic options, therapeutic cancer vaccines are one of the most essential players. Although great progress has been made in research on tumor antigen vaccines, few phase III trials have shown clinical benefits. One of the reasons lies in obstruction from the tumor microenvironment (TME). Meanwhile, the therapeutic cancer vaccine reshapes the TME in an ambivalent way, leading to immune stimulation or immune escape. In this review, we summarize recent progress on the interaction between therapeutic cancer vaccines and the TME. With respect to vaccine resistance, innate immunosuppressive TME components and acquired resistance caused by vaccination are both involved. Understanding the underlying mechanism of this crosstalk provides insight into the treatment of cancer by directly targeting the TME or synergizing with other therapeutics.

Breast cancer vaccines: New insights into immunomodulatory and nano-therapeutic approaches

Breast cancer (BC) is known to be a highly heterogeneous disease that is clinically subdivided into four primary molecular subtypes, each having distinct morphology and clinical implications. These subtypes are principally defined by hormone receptors and other proteins involved (or not involved) in BC development. BC therapeutic vaccines [including peptide-based vaccines, protein-based vaccines, nucleic acid-based vaccines (DNA/RNA vaccines), bacterial/viral-based vaccines, and different immune cell-based vaccines] have emerged as an appealing class of cancer immunotherapeutics when used alone or combined with other immunotherapies. Employing the immune system to eliminate BC cells is a novel therapeutic modality. The benefit of active immunotherapies is that they develop protection against neoplastic tissue and readjust the immune system to an anti-tumor monitoring state. Such immunovaccines have not yet shown effectiveness for BC treatment in clinical trials. In recent years, nanomedicines have opened new windows to increase the effectiveness of vaccinations to treat BC. In this context, some nanoplatforms have been designed to efficiently deliver molecular, cellular, or subcellular vaccines to BC cells, increasing the efficacy and persistence of anti-tumor immunity while minimizing undesirable side effects. Immunostimulatory nano-adjuvants, liposomal-based vaccines, polymeric vaccines, virus-like particles, lipid/calcium/phosphate nanoparticles, chitosan-derived nanostructures, porous silicon microparticles, and selenium nanoparticles are among the newly designed nanostructures that have been used to facilitate antigen internalization and presentation by antigen-presenting cells, increase antigen stability, enhance vaccine antigenicity and remedial effectivity, promote antigen escape from the endosome, improve cytotoxic T lymphocyte responses, and produce humoral immune responses in BC cells. Here, we summarized the existing subtypes of BC and shed light on immunomodulatory and nano-therapeutic strategies for BC vaccination. Finally, we reviewed ongoing clinical trials on BC vaccination and highlighted near-term opportunities for moving forward.

Interleukin 2-Based Fusion Proteins for the Treatment of Cancer

Interleukin 2 (IL-2) plays a fundamental role in both immune activation and tolerance and has revolutionized the field of cancer immunotherapy since its discovery. The ability of IL-2 to mediate tumor regression in preclinical and clinical settings led to FDA approval for its use in the treatment of metastatic renal cell carcinoma and metastatic melanoma in the 1990s. Although modest success is observed in the clinic, cancer patients receiving IL-2 therapy experience a wide array of side effects ranging from flu-like symptoms to life-threatening conditions such as vascular leak syndrome. Over the past three decades, efforts have focused on circumventing IL-2-related toxicities by engineering methods to localize IL-2 to the tumor or secondary lymphoid tissue, preferentially activate CD8⁺ T cells and NK cells, and alter pharmacokinetic properties to increase bioavailability. This review summarizes the various IL-2-based strategies that have emerged, with a focus on chimeric fusion methods.

Advancements in Human Breast Cancer Targeted Therapy and Immunotherapy

Human breast cancer treatment regimens have evolved greatly due to the significant advances in understanding the molecular mechanisms and pathways of the common subtypes of breast cancer. In this review, we discuss recent progress in breast cancer targeted therapy and immunotherapy as well as ongoing clinical trials. We also highlight the potential of combination therapies and personalized approaches to improve clinical outcomes. Targeted therapies have surpassed the hormone receptors and the human epidermal growth factor receptor 2 (HER2) to include many other molecules in targetable pathways such as the epidermal growth factor receptor (EGFR), poly (adenosine diphosphate-ribose) polymerase (PARP), and cyclin-dependent kinase 4/6 (CDK4/6). However, resistance to targeted therapy persists, underpinning the need for more efficacious therapies. Immunotherapy is considered a milestone in breast cancer treatments, including the engineered immune cells (CAR-T cell therapy) to better target the tumor cells, vaccines to stimulate the patient's immune system against tumor antigens, and checkpoint inhibitors (PD-1, PD-L1, and CTLA4) to block molecules that mediate immune inhibition. Targeted therapies and immunotherapy tested in breast cancer clinical trials are discussed here, with special emphasis on combinatorial approaches which are believed to maximize treatment efficacy and enhance patient survival.

Extracellular Matrix: Emerging Roles and Potential Therapeutic Targets for Breast Cancer

Increasing evidence shows that the extracellular matrix (ECM) is an important regulator of breast cancer (BC). The ECM comprises of highly variable and dynamic components. Compared with normal breast tissue under homeostasis, the ECM undergoes many changes in composition and organization during BC progression. Induced ECM proteins, including fibrinogen, fibronectin, hyaluronic acid, and matricellular proteins, have been identified as important components of BC metastatic cells in recent years. These proteins play major roles in BC progression, invasion, and metastasis. Importantly, several specific ECM molecules, receptors, and remodeling enzymes are involved in promoting resistance to therapeutic intervention. Additional analysis of these ECM proteins and their downstream signaling pathways may reveal promising therapeutic targets against BC. These potential drug targets may be combined with new nanoparticle technologies. This review summarizes recent advances in functional nanoparticles that target the ECM to treat BC. Accurate nanomaterials may offer a new approach to BC treatment.

Utilizing Immunocytokines for Cancer Therapy

Cytokine therapy for cancer has indicated efficacy in certain diseases but is generally accompanied by severe toxicity. The field of antibody-cytokine fusion proteins (immunocytokines) arose to target these effector molecules to the tumor environment in order to expand the therapeutic window of cytokine therapy. Pre-clinical evidence has shown the increased efficacy and decreased toxicity of various immunocytokines when compared to their cognate unconjugated cytokine. These anti-tumor properties are markedly enhanced when combined with other treatments such as chemotherapy, radiotherapy, and checkpoint inhibitor antibodies. Clinical trials that have continued to explore the potential of these biologics for cancer therapy have been conducted. This review covers the in vitro, in vivo, and clinical evidence for the application of immunocytokines in immuno-oncology.

Vaccine Therapies for Cancer: Then and Now

There are strong biologic and preclinical rationales for the development of therapeutic cancer vaccines; however, the clinical translation of this treatment strategy has been challenging. It is now understood that many previous clinical trials of cancer vaccines used target antigens or vaccine designs that inherently lacked sufficient immunogenicity to induce clinical responses. Despite the historical track record, breakthrough advances in cancer immunobiology and vaccine technologies have supported continued interest in therapeutic cancer vaccinations, with the hope that next-generation vaccine strategies will enable patients with cancer to develop long-lasting anti-tumor immunity. There has been substantial progress identifying antigens and vaccine vectors that lead to strong and broad T cell responses, tailoring vaccine designs to achieve optimal antigen presentation, and finding combination partners employing complementary mechanisms of action (e.g., checkpoint inhibitors) to overcome the diverse methods cancer cells use to evade and suppress the immune system. Results from randomized, phase 3 studies testing therapeutic cancer vaccines based on these advances are eagerly awaited. Here, we summarize the successes and failures in the clinical development of cancer vaccines, address how this historical experience and advances in science and technology have shaped efforts to improve vaccines, and offer a clinical perspective on the future role of vaccine therapies for cancer.

Targeting phosphatidylserine for Cancer therapy: prospects and challenges

Cancer is a leading cause of mortality and morbidity worldwide. Despite major improvements in current therapeutic methods, ideal therapeutic strategies for improved tumor elimination are still lacking. Recently, immunotherapy has attracted much attention, and many immune-active agents have been approved for clinical use alone or in combination with other cancer drugs. However, some patients have a poor response to these agents. New agents and strategies are needed to overcome such deficiencies. Phosphatidylserine (PS) is an essential component of bilayer cell membranes and is normally present in the inner leaflet. In the physiological state, PS exposure on the external leaflet not only acts as an engulfment signal for phagocytosis in apoptotic cells but also participates in blood coagulation, myoblast fusion and immune regulation in nonapoptotic cells. In the tumor microenvironment, PS exposure is significantly increased on the surface of tumor cells or tumor cell-derived microvesicles, which have innate immunosuppressive properties and facilitate tumor growth and metastasis. To date, agents targeting PS have been developed, some of which are under investigation in clinical trials as combination drugs for various cancers. However, controversial results are emerging in laboratory research as well as in clinical trials, and the efficiency of PS-targeting agents remains uncertain. In this review, we summarize recent progress in our understanding of the physiological and pathological roles of PS, with a focus on immune suppressive features. In addition, we discuss current drug developments that are based on PS-targeting strategies in both experimental and clinical studies. We hope to provide a future research direction for the development of new agents for cancer therapy.

Combining doxorubicin with stearylamine-bearing liposomes elicits Th1 cytokine responses and cures metastasis in a mouse model

Surface exposed phosphatidylserine (PS) of cancer aids it to evade immune surveillance and thereby results in tumor progression. Earlier, we reported that PS targeting cationic liposomes, phosphatidylcholine-stearylamine (PC-SA), alone and in combination with doxorubicin can result in complete remission of B16F10 melanoma in C57BL/6 mice without signs of toxicity. Inducing an immunogenic response is highly crucial for any cancer therapy as it is essential in improving the tumor microenvironment for any drug to act. Herein, we demonstrate that PC-SA, besides having tumor reducing ability, elicits a strong immune response. The combination therapy (PC-SA-DOX) is superior to free DOX in enhancing the anti-tumor immune effect on CD4-positive and CD8-positive T cells for IFN-γ, IL-2 and TNF-α production in sera and splenic culture supernatants of B16F10 tumor-induced mice. An upregulation of IL-12 and NO production is evidenced in spleen cultures of these mice, thereby showing a promising role of both Th1 type and innate immune response for host anti-tumor activity. Complete elimination of cancer is sometimes accomplished by surgery, but its effectiveness is often limited due to the propensity of cancers to spread to distant organs by metastasis. In our present study, we show that in PC-SA-DOX treated mice, the elevated Th1 cytokine levels create an immuno-protective environment which thereby facilitates in curing lung metastasis. Our results, therefore, warrant the need of effective immune stimulation by anticancer formulations for inhibition of solid tumors and metastasis, demonstrated by the liposomal DOX formulation.

A Generic Coordination Assembly-Enabled Nanocoating of Individual Tumor Cells for Personalized Immunotherapy

A generic and effective tumor cells encapsulation strategy enabled by metal-organic coordination is developed to prepare a vaccine for personalized immunotherapy. Specifically, an epigallocatechin-3-gallate (EGCG)-Al(III) coordination layer is in situ formed onto individual living cells in aqueous phase and the process can be completed within an hour. 98% of proteins in the cells are entrapped within the microparticles, which are endowed with high antigens loading capacity. The microparticles enhance the uptake efficiency of antigens, protect antigens from degradation in vivo, and delay the retention time of antigens in the lymph nodes. Moreover, dendritic cells (DCs) activation is triggered by the microparticles, and simultaneously, the expression of costimulation marker on DCs and the production of Th1-related cytokines are significantly upregulated. Moreover, six kinds of tumor cells are utilized and successfully coated with the EGCG/Al(III) layer, suggesting the generalization of this strategy. More importantly, the microparticles exhibit a comparative antitumor effect with polyinosinic-polycytidylic acid (PolyI:C) in B16 pulmonary metastasis model. Overall, the encapsulation strategy enabled by metal-organic coordination can be potentially useful for personalized immunotherapy customized to individual patient's tumor cells.

Antibody-cytokine fusion proteins: Biopharmaceuticals with immunomodulatory properties for cancer therapy

Cytokines have long been used for therapeutic applications in cancer patients. Substantial side effects and unfavorable pharmacokinetics limit their application and may prevent dose escalation to therapeutically active regimens. Antibody-cytokine fusion proteins (often referred to as immunocytokines) may help localize immunomodulatory cytokine payloads to the tumor, thereby activating anticancer immune responses. A variety of formats (e.g., intact IgGs or antibody fragments), molecular targets (e.g., extracellular matrix components and cell membrane antigens) and cytokine payloads have been considered for the development of this novel class of biopharmaceuticals. This review presents the basic concepts on the design and engineering of immunocytokines, reviews their potential limitations, points out emerging opportunities and summarizes key features of preclinical and clinical-stage products.

Current Approaches in Development of Immunotherapeutic Vaccines for Breast Cancer

Cancer is the leading cause of death worldwide. In developed as well as developing countries, breast cancer is the most common cancer found among women. Currently, treatment of breast cancer consists mainly of surgery, chemotherapy, hormone therapy, and radiotherapy. In recent years, because of increased understanding of the therapeutic potential of immunotherapy in cancer prevention, cancer vaccines have gained importance. Here, we review various immunotherapeutic breast cancer vaccines including peptide-based vaccines, whole tumor cell vaccines, gene-based vaccines, and dendritic cell vaccines. We also discuss novel nanotechnology-based approaches to improving breast cancer vaccine efficiency.

Immunocytokines and bispecific antibodies: two complementary strategies for the selective activation of immune cells at the tumor site

The activation of the immune system for a selective removal of tumor cells represents an attractive strategy for the treatment of metastatic malignancies, which cannot be cured by existing methodologies. In this review, we examine the design and therapeutic potential of immunocytokines and bispecific antibodies, two classes of bifunctional products which can selectively activate the immune system at the tumor site. Certain protein engineering aspects, such as the choice of the antibody format, are common to both classes of therapeutic agents and can have a profound impact on tumor homing performance in vivo of individual products. However, immunocytokines and bispecific antibodies display different mechanisms of action. Future research activities will reveal whether an additive of even synergistic benefit can be obtained from the judicious combination of these two types of biopharmaceutical agents.

Imaging and Therapy of Pancreatic Cancer with Phosphatidylserine-Targeted Nanovesicles

Pancreatic cancer remains one of the most intractable cancers, with a dismal prognosis reflected by a 5-year survival of ~6%. Since early disease symptoms are undefined and specific biomarkers are lacking, about 80% of patients present with advanced, inoperable tumors that represent a daunting challenge. Despite many clinical trials, no single chemotherapy agent has been reliably associated with objective response rates above 10% or median survival longer than 5 to 7 months. Although combination chemotherapy regimens have in recent years provided some improvement, overall survival (8-11 months) remains very poor. There is therefore a critical need for novel therapies that can improve outcomes for pancreatic cancer patients. Here, we present a summary of the current therapies used in the management of advanced pancreatic cancer and review novel therapeutic strategies that target tumor biomarkers. We also describe our recent research using phosphatidylserine-targeted saposin C-coupled dioleoylphosphatidylserine nanovesicles for imaging and therapy of pancreatic cancer.

Effective binding of a phosphatidylserine-targeting antibody to Ebola virus infected cells and purified virions

Ebola virus is responsible for causing severe hemorrhagic fevers, with case fatality rates of up to 90%. Currently, no antiviral or vaccine is licensed against Ebola virus. A phosphatidylserine-targeting antibody (PGN401, bavituximab) has previously been shown to have broad-spectrum antiviral activity. Here, we demonstrate that PGN401 specifically binds to Ebola virus and recognizes infected cells. Our study provides the first evidence of phosphatidylserine-targeting antibody reactivity against Ebola virus.

Targeting specificity of dendritic cells on breast cancer stem cells: in vitro and in vivo evaluations

Breast cancer is a leading cause of death in women, and almost all complications are due to chemotherapy resistance. Drug-resistant cells with stem cell phenotypes are thought to cause failure in breast cancer chemotherapy. Dendritic cell (DC) therapy is a potential approach to eradicate these cells. This study evaluates the specificity of DCs for breast cancer stem cells (BCSCs) in vitro and in vivo. BCSCs were enriched by a verapamil-resistant screening method, and reconfirmed by ALDH expression analysis and mammosphere assay. Mesenchymal stem cells (MSCs) were isolated from allogeneic murine bone marrow. DCs were induced from bone marrow-derived monocytes with 20 ng/mL GC-MSF and 20 ng/mL IL-4. Immature DCs were primed with BCSC- or MSC-derived antigens to make two kinds of mature DCs: BCSC-DCs and MSC-DCs, respectively. In vitro ability of BCSC-DCs and MSC-DCs with cytotoxic T lymphocytes (CTLs) to inhibit BCSCs was tested using the xCELLigence technique. In vivo, BCSC-DCs and MSC-DCs were transfused into the peripheral blood of BCSC tumor-bearing mice. The results show that in vitro BCSC-DCs significantly inhibited BCSC proliferation at a DC:CTL ratio of 1:40, while MSC-DCs nonsignificantly decreased BCSC proliferation. In vivo, tumor sizes decreased from 18.8% to 23% in groups treated with BCSC-DCs; in contrast, tumors increased 14% in the control group (RPMI 1640) and 47% in groups treated with MSC-DCs. The results showed that DC therapy could target and be specific to BCSCs. DCs primed with MSCs could trigger tumor growth. These results also indicate that DCs may be a promising therapy for treating drug-resistant cancer cells as well as cancer stem cells.

Dendritic cell-based vaccines: clinical applications in breast cancer

Recent evidence suggests that the immune system is involved in the carcinogenesis process and the antitumor immune responses impact the clinical outcome, thus emphasizing the concept of cancer immune surveillance. In this context, dendritic cells (DCs) seem to play a crucial role, as they are the most potent antigen-presenting cells (APCs) and are able to stimulate naive T lymphocytes and to generate memory T lymphocytes. Immunotherapy with DC-based vaccines is a very attractive approach to treat cancer, offering the potential for high tumor-specific cytotoxicity. Although breast cancer (BC) is traditionally considered a poorly immunogenic tumor, increasing numbers of both preclinical and clinical studies demonstrate that vaccination with DCs is capable of inducing an antitumor-specific response, while being well tolerated and safe. However, clinical objective responses are still disappointing and many reasons may explain the difficulty of developing effective DC-based therapies for BC. In this review, we discuss the characteristics of DCs, and the major clinical indications for DC-based immunotherapy in BC with related drawbacks.

The IL-2 cytokine family in cancer immunotherapy

The use of cytokines from the IL-2 family (also called the common γ chain cytokine family) such as interleukin (IL)-2, IL-7, IL-15, and IL-21 to activate the immune system of cancer patients is one of the most important areas of current cancer immunotherapy research. The infusion of IL-2 at low or high doses for multiple cycles in patients with metastatic melanoma and renal cell carcinoma was the first successful immunotherapy for cancer proving that the immune system could completely eradicate tumor cells under certain conditions. The initial clinical success observed in some IL-2-treated patients encouraged further efforts focused on developing and improving the application of other IL-2 family cytokines (IL-4, IL-7, IL-9, IL-15, and IL-21) that have unique biological effects playing important roles in the development, proliferation, and function of specific subsets of lymphocytes at different stages of differentiation with some overlapping effects with IL-2. IL-7, IL-15, and IL-21, as well as mutant forms or variants of IL-2, are now also being actively pursued in the clinic with some measured early successes. In this review, we summarize the current knowledge on the biology of the IL-2 cytokine family focusing on IL-2, IL-15 and IL-21. We discuss the similarities and differences between the signaling pathways mediated by these cytokines and their immunomodulatory effects on different subsets of immune cells. Current clinical application of IL-2, IL-15 and IL-21 either as single agents or in combination with other biological agents and the limitation and potential drawbacks of these cytokines for cancer immunotherapy are also described. Lastly, we discuss the future direction of research on these cytokines, such as the development of new cytokine mutants and variants for improving cytokine-based immunotherapy through differential binding to specific receptor subunits.

Allogeneic tumor cell vaccines: the promise and limitations in clinical trials

The high mortality rate associated with cancer and its resistance to conventional treatments such as radiation and chemotherapy has led to the investigation of a variety of anti-cancer immunotherapies. The development of novel immunotherapies has been bolstered by the discovery of tumor-associated antigens (TAAs), through gene sequencing and proteomics. One such immunotherapy employs established allogeneic human cancer cell lines to induce antitumor immunity in patients through TAA presentation. Allogeneic cancer immunotherapies are desirable in a clinical setting due to their ease of production and availability. This review aims to summarize clinical trials of allogeneic tumor immunotherapies in various cancer types. To date, clinical trials have shown limited success due potentially to extensive degrees of inter- and intra-tumoral heterogeneity found among cancer patients. However, these clinical results provide guidance for the rational design and creation of more effective allogeneic tumor immunotherapies for use as monotherapies or in combination with other therapies.

Whole-cell vaccine coated with recombinant calreticulin enhances activation of dendritic cells and induces tumour-specific immune responses

It has been reported that calreticulin (CRT) plays an important role in mediating immunogenic tumour cell death. In the process of tumour cell apoptosis induced by specific stimuli, CRT is quickly transferred from the endoplasmic reticulum to the cell membrane. As a specific ligand, CRT on the surface of apoptotic tumour cells could mediate the recognition and clearance of apoptotic tumour cells by professional and non-professional phagocytes. In our previous studies, we used B16-F1 mouse melanoma cells coated with mCRT-vGPCR (a recombinant fusion protein of mouse CRT and virus G-protein-coupled receptor) as a whole-cell tumour vaccine to immunise experimental animals and found that this whole-cell vaccine could strongly inhibit the growth of homologous tumours. In this study, we further evaluated immune responses induced by this mCRT-vGPCR-coated whole-cell vaccine both in vivo and in vitro. An in vitro phagocytosis assay showed that the mCRT-vGPCR on the cell surface greatly enhanced the engulfment of B16-F1 cells by dendritic cells (DCs). The specific antitumour immune response was observed when the mCRT-vGPCR-coated B16-F1 cells were used as a whole-cell tumour vaccine to immune mice, which included significantly enhanced cytotoxic T lymphocyte (CTL) activities and increased the number of IFN-γ-producing T cells. These results indicate that the mCRT-vGPCR-coated whole-cell vaccine can induce specific antitumour immunity though the activation of DCs. These results may provide an experimental basis for the development of new tumour vaccines.

Formulation and evaluation of oral microparticulate ovarian cancer vaccines

Ovarian cancer is the fifth most leading cause of cancer related deaths in women in the US. Customized immunotherapeutic strategies may serve as an alternative method to control the recurrence or progression of ovarian cancer and to avoid severe adverse effects of chemotherapy. In this study, a microparticulate vaccine using whole cell lysate of a murine ovarian cancer cell line, ID8 was prepared with the use of a spray dryer. These particles were designed for oral delivery using enteric polymers such as methacrylic copolymer, Eudragit(®) FS30D and hydroxyl propyl methyl cellulose acetate succinate. These particles were targeted for uptake via microfold cell (M-cell) in Peyer's patches of small intestine using M-cell targeting ligand, Aleuria aurantia lectin. The interleukins (ILs) such as IL-2 and IL-12 were added to the vaccine formulation to further enhance the immune response. The particles obtained were of 1.58±0.62 μm size with a charge of 12.48±2.32 mV. The vaccine efficacy was evaluated by administering the particles via oral route to C57BL/6 female mice. At the end of vaccination, mice were challenged with live tumor cells. Vaccinated mice showed significant (around six-fold) retardation of tumor volume in comparison to non-vaccinated animals for 3 weeks after the tumor challenge (p<0.001). The serum IgG antibody levels were found to be elevated in case of vaccinated animals in comparison to non-vaccinated group (p<0.05). Analysis of IgG1 titers (indicative of Th2 response) and IgG2a titers (indicative of Th1 response) showed a mixed Th1 and Th2 immune response in case vaccine alone and Th2 response in case of vaccine with interleukins group. Moreover, CD8+ T-cell, CD4+ T-cell and B-cell populations in different lymphatic organs were elevated in case of vaccinated mice. Thus, whole cell lysate vaccine microparticles formulated by spray drying could trigger humoral as well as cellular immune response when administered orally. Such vaccine could potentially be an effective treatment for patients with residual tumor or high tumor-relapse probability.

Immunocytokines: a novel class of potent armed antibodies

Several cytokines have been investigated in clinical trials, based on their potent therapeutic activity observed in animal models of cancer and other diseases. However, substantial toxicities are often reported at low doses, thus preventing escalation to therapeutically active regimens. The use of recombinant antibodies or antibody fragments as delivery vehicles promises to enhance greatly the therapeutic index of pro-inflammatory and anti-inflammatory cytokines. This review surveys preclinical and clinical data published in the field of antibody-cytokine fusions (immunocytokines). Molecular determinants (such as molecular format, valence, target antigen), which crucially contribute to immunocytokine performance in vivo, are discussed in the article, as well as recent trends for the combined use of this novel class of biopharmaceuticals with other therapeutic agents.