Enhancing cancer vaccines with immunomodulators

Novel therapeutic agents in clinical trials: emerging approaches in cancer therapy

Novel therapeutic agents in clinical trials offer a paradigm shift in the approach to battling this prevalent and destructive disease, and the area of cancer therapy is on the precipice of a trans formative revolution. Despite the importance of tried-and-true cancer treatments like surgery, radiation, and chemotherapy, the disease continues to evolve and adapt, making new, more potent methods necessary. The field of cancer therapy is currently witnessing the emergence of a wide range of innovative approaches. Immunotherapy, including checkpoint inhibitors, CAR-T cell treatment, and cancer vaccines, utilizes the host's immune system to selectively target and eradicate malignant cells while minimizing harm to normal tissue. The development of targeted medicines like kinase inhibitors and monoclonal antibodies has allowed for more targeted and less harmful approaches to treating cancer. With the help of genomics and molecular profiling, "precision medicine" customizes therapies to each patient's unique genetic makeup to maximize therapeutic efficacy while minimizing unwanted side effects. Epigenetic therapies, metabolic interventions, radio-pharmaceuticals, and an increasing emphasis on combination therapy with synergistic effects further broaden the therapeutic landscape. Multiple-stage clinical trials are essential for determining the safety and efficacy of these novel drugs, allowing patients to gain access to novel treatments while also furthering scientific understanding. The future of cancer therapy is rife with promise, as the integration of artificial intelligence and big data has the potential to revolutionize early detection and prevention. Collaboration among researchers, and healthcare providers, and the active involvement of patients remain the bedrock of the ongoing battle against cancer. In conclusion, the dynamic and evolving landscape of cancer therapy provides hope for improved treatment outcomes, emphasizing a patient-centered, data-driven, and ethically grounded approach as we collectively strive towards a cancer-free world.

Cry1Ac Protoxin Confers Antitumor Adjuvant Effect in a Triple-Negative Breast Cancer Mouse Model by Improving Tumor Immunity

The Cry1Ac protoxin from Bacillus thuringiensis is a systemic and mucosal adjuvant, able to confer protective immunity in different infection murine models and induce both Th1 and TCD8+ cytotoxic lymphocyte responses, which are required to induce antitumor immunity. The Cry1Ac toxin, despite having not being characterized as an adjuvant, has also proved to be immunogenic and able to activate macrophages. Here, we investigated the potential antitumor adjuvant effect conferred by the Cry1Ac protoxin and Cry1Ac toxin in a triple negative breast cancer (TNBC) murine model. First, we evaluated the ability of Cry1Ac proteins to improve dendritic cell (DC) activation and cellular response through intraperitoneal (i.p.) coadministration with the 4T1 cellular lysate. Mice coadministered with the Cry1Ac protoxin showed an increase in the number and activation of CD11c+MHCII- and CD11c+MHCII+^low in the peritoneal cavity and an increase in DC activation (CD11c+MHCII+) in the spleen. Cry1Ac protoxin increased the proliferation of TCD4+ and TCD8+ lymphocytes in the spleen and mesenteric lymph nodes (MLN), while the Cry1Ac toxin only increased the proliferation of TCD4+ and TCD8+ in the MLN. Remarkably, when tested in the in vivo TNBC mouse model, prophylactic immunizations with 4T1 lysates plus the Cry1Ac protoxin protected mice from developing tumors. The antitumor effect conferred by the Cry1Ac protoxin also increased specific cytotoxic T cell responses, and prevented the typical tumor-related decrease of T cells (TCD3+ and TCD4+) as well the increase of myeloid-derived suppressor cells (MDSC) in spleen. Also in the tumor microenvironment of mice coadministered twice with Cry1Ac protoxin immunological improvements were found such as reductions in immunosupressive populations (T regulatory lymphocytes and MDSC) along with increases in macrophages upregulating CD86. These results show a differential antitumor adjuvant capability of Cry1Ac proteins, highlighting the ability of Cry1Ac protoxin to enhance local and systemic tumor immunity in TNBC. Finally, using a therapeutic approach, we evaluated the coadministration of Cry1Ac protoxin with doxorubicin. A significant reduction in tumor volume and lung metastasis was found, with increased intratumoral levels of tumor necrosis factor-α and IL-6 with respect to the vehicle group, further supporting its antitumor applicability.

Trial Watch: experimental TLR7/TLR8 agonists for oncological indications

Resiquimod (R848) and motolimod (VTX-2337) are second-generation experimental derivatives of imiquimod, an imidazoquinoline with immunostimulatory properties originally approved by the US Food and Drug Administration for the topical treatment of actinic keratosis and genital warts more than 20 years ago. Both resiquimod and motolimod operate as agonists of Toll-like receptor 7 (TLR7) and/or TLR8, in thus far delivering adjuvant-like signals to antigen-presenting cells (APCs). In line with such an activity, these compounds are currently investigated as immunostimulatory agents for the treatment of various malignancies, especially in combination with peptide-based, dendritic cell-based, cancer cell lysate-based, or DNA-based vaccines. Here, we summarize preclinical and clinical evidence recently collected to support the development of resiquimod and motolimod and other TLR7/TLR8 agonists as anticancer agents.

Harnessing Dendritic Cells for Poly (D,L-lactide-co-glycolide) Microspheres (PLGA MS)-Mediated Anti-tumor Therapy

With emerging success in fighting off cancer, chronic infections, and autoimmune diseases, immunotherapy has become a promising therapeutic approach compared to conventional therapies such as surgery, chemotherapy, radiation therapy, or immunosuppressive medication. Despite the advancement of monoclonal antibody therapy against immune checkpoints, the development of safe and efficient cancer vaccine formulations still remains a pressing medical need. Anti-tumor immunotherapy requires the induction of antigen-specific CD8+ cytotoxic T lymphocyte (CTL) responses which recognize and specifically destroy tumor cells. Due to the crucial role of dendritic cells (DCs) in initiating anti-tumor immunity, targeting tumor antigens to DCs has become auspicious in modern vaccine research. Over the last two decades, micron- or nanometer-sized particulate delivery systems encapsulating tumor antigens and immunostimulatory molecules into biodegradable polymers have shown great promise for the induction of potent, specific and long-lasting anti-tumor responses in vivo. Enhanced vaccine efficiency of the polymeric micro/nanoparticles has been attributed to controlled and continuous release of encapsulated antigens, efficient targeting of antigen presenting cells (APCs) such as DCs and subsequent induction of CTL immunity. Poly (D, L-lactide-co-glycolide) (PLGA), as one of these polymers, has been extensively studied for the design and development of particulate antigen delivery systems in cancer therapy. This review provides an overview of the current state of research on the application of PLGA microspheres (PLGA MS) as anti-tumor cancer vaccines in activating and potentiating immune responses attempting to highlight their potential in the development of cancer therapeutics.

The Modified Vaccination Technique

In addition to active and passive immunizations, there is a third method of immunization, the modified vaccination technique, which is based on injecting a combination of target antigens and antibodies against this antigen. The vaccine is essentially comprised of immune complexes with pre-determined immune-inducing components. When such an immune complex (target antigen × antibody against the target antigen) with a slight antigen excess is administered, it evokes a corrective immune response by the production of the same antibody with the same specificity against the target antigen that is present in the immune complex (pre-determined immune response).

Immunotherapy approach with recombinant survivin adjuvanted with alum and MIP suppresses tumor growth in murine model of breast cancer

Survivin has received attention as a potential target for cancer immunotherapy because of its crucial role in oncogenesis. We undertook this study to evaluate the immunotherapeutic potential of combination of recombinant survivin along with adjuvant alum and immune modulator Mycobacterium indicus pranii (MIP). In vivo efficacy of the combination was studied in an invasive murine breast cancer model. Recombinant survivin protein was purified from Escherichia coli based expression system and characterized by western blotting. Purified survivin protein was combined with alum and MIP and was used for immunization of Balb/c mice. Antigen-primed animals were then challenged with syngeneic mammary tumor cells known as 4T-1. Balb/c mice spontaneously develop tumor when inoculated with 4T-1 cells. Antigen and adjuvant combination was immunogenic and significantly suppressed tumor growth in mice immunized with combination of recombinant survivin (10 µg), alum, and MIP. This is the first report that describes a combination immunotherapy approach using recombinant survivin, alum, and MIP in highly metastatic murine breast cancer model and holds promise for development of new biotherapeutics for cancer.

Hierarchically porous, and Cu- and Zn-containing γ-AlOOH mesostrands as adjuvants for cancer immunotherapy

Alum is the only licensed adjuvant by Food and Drug Administration of USA used in many human vaccines and has excellent safety record in clinical applications. However, alum hardly induces T helper 1 (Th1) immune responses that are required for anti-tumor immunity. In the present study, we fabricated hierarchical copper- and zinc- buds dressing γ-AlOOH mesostrands (Cu- and Zn-AMSs) with randomly wrinkled morphology, mesoscale void- or cave-like pockets, high-exposed surface coverage sites, and positive charge streams in saline. We confirmed that Cu- and Zn-AMSs promoted intracellular uptake of model cancer antigen (ovalbumin, OVA) by THP-1-differentiated macrophage-like cells in vitro. Moreover, Cu- and Zn-AMSs enhanced maturation and cytokine release of bone marrow dendritic cells in vitro. In vivo study demonstrated that Cu- and Zn-AMSs markedly induced anti-tumor-immunity and enhanced CD₄⁺ and CD₈⁺ T cell populations in splenocytes of mice. These findings demonstrated that hierarchical copper- and zinc- buds dressing γ-AlOOH mesostrands, which are oriented in randomly wrinkled matrice, are suitable platforms as novel adjuvants for cancer immunotherapy.

Ginsenoside Rh2 enhances the antitumor immunological response of a melanoma mice model

The treatment of malignant tumors following surgery is important in preventing relapse. Among all the post-surgery treatments, immunomodulators have demonstrated satisfactory effects on preventing recurrence according to recent studies. Ginsenoside is a compound isolated from panax ginseng, which is a famous traditional Chinese medicine. Ginsenoside aids in killing tumor cells through numerous processes, including the antitumor processes of ginsenoside Rh2 and Rg1, and also affects the inflammatory processes of the immune system. However, the role that ginsenoside serves in antitumor immunological activity remains to be elucidated. Therefore, the present study aimed to analyze the effect of ginsenoside Rh2 on the antitumor immunological response. With a melanoma mice model, ginsenoside Rh2 was demonstrated to inhibit tumor growth and improved the survival time of the mice. Ginsenoside Rh2 enhanced T-lymphocyte infiltration in the tumor and triggered cytotoxicity in spleen lymphocytes. In addition, the immunological response triggered by ginsenoside Rh2 could be transferred to other mice. In conclusion, the present study provides evidence that ginsenoside Rh2 treatment enhanced the antitumor immunological response, which may be a potential therapy for melanoma.

Construction of random tumor transcriptome expression library for creating and selecting novel tumor antigens

Novel tumor antigens are necessary for the development of efficient tumor vaccines for overcoming the immunotolerance and immunosuppression induced by tumors. Here, we developed a novel strategy to create tumor antigens by construction of random tumor transcriptome expression library (RTTEL). The complementary DNA (cDNA) from S180 sarcoma was used as template for arbitrarily amplifying gene fragments with random primers by PCR, then ligated to the C-terminal of HSP65 in a plasmid pET28a-HSP for constructing RTTEL in Escherichia coli. A novel antigen of A5 was selected from RTTEL with the strongest immunotherapeutic effects on S180 sarcoma. Adoptive immunotherapy with anti-A5 sera also inhibited tumor growth, further confirming the key antitumor roles of A5-specific antibodies in mice. A5 contains a sequence similar to protein-L-isoaspartate (D-aspartate) O-methyltransferase (PCMT1). The antisera of A5 were verified to cross-react with PCMT1 by Western blotting assay and vice versa. Both anti-A5 sera and anti-PCMT1 sera could induce antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity toward S180 cells by in vitro assay. Further assay with fluorescent staining showed that PCMT1 is detectable on the surface of S180 cells. Summary, the strategy to construct RTTEL is potential for creating and screening novel tumor antigens to develop efficient tumor vaccines. By RTTEL, we successfully created a protein antigen of A5 with significant immunotherapeutic effects on S180 sarcoma by induction of antibodies targeting for PCMT1.

IMA901: a multi-peptide cancer vaccine for treatment of renal cell cancer

Despite a major improvement in the treatment of advanced kidney cancer by the recent introduction of targeted agents such as multi-kinase inhibitors, long-term benefits are still limited and a significant unmet medical need remains for this disease. Cancer immunotherapy has shown its potential by the induction of long-lasting responses in a small subset of patients, however, the unspecific immune interventions with (high dose) cytokines used so far are associated with significant side effects. Specific cancer immunotherapy may circumvent these problems by attacking tumor cells while sparing normal tissue with the use of multi-peptide vaccination being one of the most promising strategies. We here summarize the clinical and translational data from phase I and II trials investigating IMA901. Significant associations of clinical benefit with detectable T cell responses against the IMA901 peptides and encouraging survival data in treated patients has prompted the start of a randomized, controlled phase III trial in 1st line advanced RCC with survival results expected toward the end of 2015. Potential combination strategies with the recently discovered so-called checkpoint inhibitors are also discussed.

Cancer vaccines: Looking to the future

These are exciting times for the field of cancer immunotherapy. Although the clinical efficacy of monoclonal antibodies has been demonstrated since the early 1990s, the therapeutic profile of other immunotherapeutic approaches-especially vaccines-has not yet been formally clarified. However, the recent success of several immunotherapeutic regimens in cancer patients has boosted the development of this treatment modality. These achievements stemmed from recent scientific advances demonstrating the tolerogenic nature of cancer and the fundamental role of the tumor immune microenvironment in the suppression of antitumor immunity. New immunotherapeutic strategies against cancer attempt to promote protective antitumor immunity while disrupting the immunoregulatory circuits that contribute to tumor tolerance. Cancer vaccines differ from other anticancer immunotherapeutics in that they initiate the dynamic process of activating the immune system so as to successfully re-establish a state of equilibrium between tumor cells and the host. This article reviews recent clinical trials involving several different cancer vaccines and describes some of the most promising immunotherapeutic approaches that harness antitumor T-cell responses. In addition, we describe strategies whereby cancer vaccines can be exploited in combination with other therapeutic approach to overcome-in a synergistic fashion-tumor immunoevasion. Finally, we discuss prospects for the future development of broad spectrum prophylactic anticancer vaccines.

Zn- and Mg- containing tricalcium phosphates-based adjuvants for cancer immunotherapy

Zn-, and Mg-containing tricalcium phosphates (TCPs) loaded with a hydrothermal extract of a human tubercle bacillus (HTB) were prepared by immersing Zn-TCP and Mg-TCP in HTB-containing supersaturated calcium phosphate solutions. The in vitro and in vivo immunogenic activities of the HTB-loaded Zn-, and Mg-TCPs (Zn-Ap-HTB and Mg-Ap-HTB, respectively) were evaluated as potential immunopotentiating adjuvants for cancer immunotherapy. The Zn-Ap-HTB and Mg-Ap-HTB adjuvants showed no obvious cytotoxicity and more effectively stimulated granulocyte-macrophage colony-stimulating factor (GM-CSF) secretion by macrophage-like cells than unprocessed HTB or HTB-loaded TCP (T-Ap-HTB) in vitro. Zn-Ap-HTB and Mg-Ap-HTB mixed with liquid-nitrogen-treated tumor tissue markedly inhibited the in vivo development of rechallenged Lewis lung carcinoma (LLC) cells compared with T-Ap-HTB and the unprocessed HTB mixed liquid-nitrogen-treated tumor tissue. Zn-Ap-HTB and Mg-Ap-HTB contributed to eliciting potent systemic antitumor immunity in vivo.

Particle-size-dependent toxicity and immunogenic activity of mesoporous silica-based adjuvants for tumor immunotherapy

Conventionally used adjuvants alone are insufficient for triggering cell-mediated immunity, although they have been successfully developed to elicit protective antibody responses in some vaccines. Here, with the aim of eliciting cell-mediated immunity, pathogen-associated molecular patterns (PAMPs) were immobilized with apatite within the pores and on the surface of mesoporous silica (MS) with particle sizes from 30 to 200nm to prepare novel MS-Ap-PAMP adjuvants, which showed cell-mediated anti-tumor immunity that was markedly improved compared to commercial alum adjuvant in vitro and in vivo. The toxicity and antitumor immunity of the MS-Ap-PAMP adjuvants were evaluated in vitro and in vivo. MS with a particle size of 200nm showed minimum in vitro cytotoxicity to NIH3T3 cells, particularly at concentrations no higher than 100μgml(-1). In particular, apatite precipitation within the pores and on the surface of MS decreased the in vitro cytotoxicity of MS particles. The MS-Ap-PAMP adjuvants showed the maximum in vitro immunogenic activity among original culture medium, PAMP and alum-PAMP. Moreover, injection of the MS-Ap-PAMP adjuvant in combination with liquid-nitrogen-treated tumor tissue (derived from Lewis lung carcinoma cells) into C57BL/6 mice markedly inhibited in vivo tumor recurrence and the development of rechallenged tumor compared to those with commercial alum adjuvant. The MS-Ap-PAMP adjuvant contributed to the elicitation of a potent systemic antitumor immunity without obvious toxicity in vivo.

Mesoporous silica-calcium phosphate-tuberculin purified protein derivative composites as an effective adjuvant for cancer immunotherapy

The synthesis of mesoporous silica/calcium phosphate composite loaded with the immunopotentiator tuberculin purified protein derivative (PPD-MS/CaP) as an effective adjuvant for cancer immunotherapy is reported here. The PPD-MS/CaP adjuvant is prepared by immersing mesoporous silica in a supersaturated calcium phosphate solution supplemented with the immunopotentiator PPD for 24 h. PPD is coprecipitated with calcium phosphate inside and on the surface of mesoporous silica. By loading the immunopotentiator PPD in the PPD-MS/CaP adjuvant, an enhanced activation of antigen-presenting cells, such as GM-CSF secretion by THP-1 differentiated macrophages, is obtained probably due to sustained PPD release and an efficient cellular uptake of PPD. The PPD-MS/CaP adjuvant mixed with liquid-N2 -treated tumor tissue effectively triggers anti-tumor immune response and markedly inhibits in vivo tumor growth. The PPD-MS/CaP adjuvant is a promising alternative for cancer immune therapy.

Tumor cells in multiple myeloma patients inhibit myeloma-reactive T cells through carcinoembryonic antigen-related cell adhesion molecule-6

Although functionally competent cytotoxic, T cells are frequently observed in malignant diseases, they possess little ability to react against tumor cells. This phenomenon is particularly apparent in multiple myeloma. We here demonstrate that cytotoxic T cells reacted against myeloma antigens when presented by autologous dendritic cells, but not by myeloma cells. We further show by gene expression profiling and flow cytometry that, similar to many other malignant tumors, freshly isolated myeloma cells expressed several carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) at varying proportions. Binding and crosslinking of CEACAM-6 by cytotoxic T cells inhibited their activation and resulted in T-cell unresponsiveness. Blocking of CEACAM-6 on the surface of myeloma cells by specific monoclonal antibodies or CEACAM-6 gene knock down by short interfering RNA restored T-cell reactivity against malignant plasma cells. These findings suggest that CEACAM-6 plays an important role in the regulation of CD8+ T-cell responses against multiple myeloma; therefore, therapeutic targeting of CEACAM-6 may be a promising strategy to improve myeloma immunotherapy.

Role of tumor vascular architecture in drug delivery

Tumor targeted drug delivery has the potential to improve cancer care by reducing non-target toxicities and increasing the efficacy of a drug. Tumor targeted delivery of a drug from the systemic circulation, however, requires a thorough understanding of tumor pathophysiology. A growing or receding (under the impact of therapy) tumor represents a dynamic environment with changes in its angiogenic status, cell mass, and extracellular matrix composition. An appreciation of the salient characteristics of tumor vascular architecture and the unique biochemical markers that may be used for targeting drug therapy is important to overcome barriers to tumor drug therapy and to facilitate targeted drug delivery. This review discusses the unique aspects of tumor vascular architecture that need to be overcome or exploited for tumor targeted drug delivery.

Antitumor activity of mixed heat shock protein/peptide vaccine and cyclophosphamide plus interleukin-12 in mice sarcoma

Background

The immune factors heat shock protein (HSP)/peptides (HSP/Ps) can induce both adaptive and innate immune responses. Treatment with HSP/Ps in cancer cell-bearing mice and cancer patients revealed antitumor immune activity. We aimed to develop immunotherapy strategies by vaccination with a mixture of HSP/Ps (mHSP/Ps, HSP60, HSP70, Gp96 and HSP110) enhanced with cyclophosphamide (CY) and interleukin-12 (IL-12).

Methods

We extracted mHSP/Ps from the mouse sarcoma cell line S180 using chromatography. The identity of proteins in this mHSP/Ps was assayed using SDS-PAGE and Western blot analysis with antibodies specific to various HSPs. BALB/C mice bearing S180 cells were vaccinated with mHSP/Ps ×3, then were injected intraperitoneally with low-dose CY and subcutaneously with IL-12, 100 μg/day, ×5. After vaccination, T lymphocytes in the peripheral blood were analyzed using FACScan and Cytotoxicity (CTL) was analyzed using lactate dehydrogenase assay. ELISPOT assay was used to evaluate interferon γ (IFN-γ), and immune cell infiltration in tumors was examined in the sections of tumor specimen.

Results

In mice vaccinated with enhanced vaccine (mHSP/Ps and CY plus IL-12), 80% showed tumor regression and long-term survival, and tumor growth inhibition rate was 82.3% (30 days), all controls died within 40 days. After vaccination, lymphocytes and polymorphonuclear leukocytes infiltrated into the tumors of treated animals, but no leukocytes infiltrated into the tumors of control mice. The proportions of natural killer cells, CD8+, and interferon-γ-secreting cells were all increased in the immune group, and tumor-specific cytotoxic T lymphocyte activity was increased.

Conclusions

In this mice tumor model, vaccination with mHSP/Ps combined with low-dose CY plus IL-12 induced an immunologic response and a marked antitumor response to autologous tumors. The regimen may be a promising therapeutic agent against tumors.

'Dressed for success' C-type lectin receptors for the delivery of glyco-vaccines to dendritic cells

Current strategies in immunotherapy for the treatment of tumors or autoimmunity focus on direct in vivo targeting of antigens to dendritic cells (DC), as these cells are the key regulators of immune responses. Multiple DC subsets can be distinguished in both humans and mice, based on phenotype and location. Moreover, recent data show that these subsets have distinct functions. All these features have implications for the design of DC-targeting vaccines. In this review we integrate recent knowledge on the different DC subsets in human and mice and how DC-expressed C-type lectin receptors (CLR) can be exploited for the induction of either antigen-specific immunity or tolerance.

CpG Oligodeoxynucleotides Enhance the Activities of CD8+ Cytotoxic T-Lymphocytes Generated by Combined hMUC1 Vaccination and hNIS Radioiodine Gene Therapy

PURPOSE

The authors evaluated whether the cytotoxicity of CD8+CTLs generated by combined hMUC1 vaccination and hNIS radioiodine gene therapy was enhanced in the presence of CpG in an established tumor model.

METHODS

CMNF cells (CT26 cells expressing hMUC1, hNIS and Firefly luciferase) were transplanted into BALB/c mice. Four and 10 days later, tumor-bearing mice were immunized intramuscularly with pcDNA3.1 or pcDNA-hMUC1 or pcDNA-hMUC1+CpG, and subsequently administered PBS or (131)I [five groups (seven mice/group): referred to as the pcDNA3.1+PBS, phMUC1+PBS, pcDNA3.1+(131)I, phMUC1+(131)I, and phMUC1+(131)I+CpG groups]. The number of CD8+IFNr+ T cells of splenocytes as well as the number of CD8+IFNr+ T cells of splenocytes re-stimulated with CD11c+ cells was determined using FACS analysis. The activities of cytotoxic T cells (CTLs) from splenocytes were investigated.

RESULTS

Marked tumor growth inhibition was observed in the phMUC1+(131)I and phMUC1+(131)I+CpG groups, but not in the other three single therapy groups. Particularly the number of CD8+IFN-γ+ T cells of splenocytes was more increased in the phMUC1+(131)I+CpG group than in the phMUC1+(131)I group. The number of CD8+IFN-γ+ T cells of splenocytes stimulated with CD11c+ cells was the most enhanced in the phMUC1+(131)I+CpG group among the five groups. Concurrently, the activities of hMUC1-associated CTLs obtained from splenocytes in the phMUC1+(131)I+CpG group were significantly greater than in the other four groups (pcDNA+PBS, phMUC1+PBS, pcDNA+(131)I, phMUC1+(131)I, and phMUC1+(131)I+CpG, 16 ± 2%, 20 ± 1%, 30 ± 2%, 60 ± 2%, and 87 ± 2%, respectively, P < 0.01).

CONCLUSION

Our data suggest that adjuvant CpG ODNs can increase the killing activities of CTLs generated by combined hMUC1 DNA vaccination and hNIS radioiodine gene therapy.

Recombinant immunotherapeutics: current state and perspectives regarding the feasibility and market

Recombinant immunotherapeutics are important biologics for the treatment and prevention of various diseases. Immunotherapy can be divided into two categories, passive and active. For passive immunotherapy, the successes of antibody and cytokine therapeutics represent a promising future and opportunities for improvements. Efforts, such as cell engineering, antibody engineering, human-like glycosylation in yeast, and Fab fragment development, have led the way to improve antibody efficacy while decreasing its high manufacturing costs. Both new cytokines and currently used cytokines have demonstrated therapeutic effects for different indications. As for active immunotherapy, recently approved HPV vaccines have encouraged the development of preventative vaccines for other infectious diseases. Immunogenic antigens of pathogenic bacteria can now be identified by genomic means (reverse vaccinology). Due to the recent outbreaks of pandemic H1N1 influenza virus, recombinant influenza vaccines using virus-like particles and other antigens have also been engineered in several different recombinant systems. However, limitations are found in existing immunotherapeutics for cancer treatment, and recent development of therapeutic cancer vaccines such as MAGE-A3 and NY-ESO-1 may provide alternative therapeutic strategy.

A TLR9 agonist enhances therapeutic effects of telomerase genetic vaccine

The telomerase reverse transcriptase (TERT) is an attractive target for cancer vaccination because its expression is reactivated in most tumors. In this study, we have evaluated the ability of a genetic vaccine targeting murine TERT (mTERT) based on DNA electroporation (DNA-EP) and adenovirus serotype 6 (Ad6) to exert therapeutic effects in combination with a novel TLR9 agonist, referred to as immune modulatory oligonucleotide (IMO), as an adjuvant. IMO was administered to mice at the same time as vaccine. IMO induced dose-dependent cytokine secretion and activation of NK cells. Most importantly, vaccination of mice with IMO in combination with mTERT vaccine conferred therapeutic benefit in tumor bearing animals and this effect was associated with increased NK, DC and T cell tumor infiltration. These data show that appropriate combination of a DNA-EP/Ad6-based cancer vaccine against TERT with IMO induces multiple effects on innate and adaptive immune responses resulting in a significant antitumor efficacy.

Strategies to enhance the therapeutic activity of cancer vaccines: using melanoma as a model

Although there has been initial success with some types of immunotherapy, such as adoptive cellular therapy and monoclonal antibody therapy for cancer, the experience with therapeutic cancer vaccines has been much less encouraging. Almost all randomized phase III trials testing therapeutic cancer vaccines have failed to meet their end points. There are several potential explanations for this, ranging from factors related to the clinical trial design and the vaccine itself. Perhaps the most important are host-related factors. Specifically, progression and metastases of many cancers are associated with induction of multiple cancer-specific immune-inhibitory pathways. These inhibitory pathways include induction of T-cell anergy through dendritic cell dysfunction, release of immunosuppressive cytokines, T-cell exhaustion through inhibitory T-cell signaling and T regulatory cell-mediated tumor-specific immune suppression. All of these pathways have been shown to be operational in patients with melanoma. To enhance the activity of therapeutic cancer vaccines, these immunosupressive pathways need to be addressed and reversed. A number of new immunomodulatory reagents that are able to interfere with some of these pathways are now being assessed in the clinic. Sanofi Pasteur designed a clinical trial in patients with advanced or metastatic melanoma that is intended to both induce tumor-specific T-cell responses and modulate or reverse some of the immune suppression pathways that the melanoma has induced. To accomplish this, the recently optimized ALVAC melanoma multi-antigen vaccine is administered with high doses of IFN-alpha. Clinical trial parameters have also been optimized to enhance the likelihood of inducing and documenting antitumor activity. Success with other therapeutic cancer vaccine approaches will likely require similar approaches in which promising immunogenic vaccines are integrated with biologically and clinically active immunomodulatory reagents.

A review of immunomodulators with reference to Canova

Immunomodulators are substances which modify the immunity of an individual to favour a particular immunological response. The immune response and the function of the immune response regulation process are described, with special reference to cancer and autoimmune disease. Homeopathy and its role in immune regulation are discussed with special reference to Canova. Canova is a homeopathic product produced, according to the Hahnemannian homeopathic method, in Brazil. Its role in cancer, bone marrow and haematopoiesis as well as macrophage and monocyte activation is reviewed. Canova seems to stabilize platelet morphology in human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS). The data suggest that the future of immunomodulators and homeopathic products which appear to have an effect on the immune response requires a better understanding of the relative need for immune activation versus immune modulation. Homeopathic products specifically need more attention.

Vaccination with vif-deleted feline immunodeficiency virus provirus, GM-CSF, and TNF-alpha plasmids preserves global CD4 T lymphocyte function after challenge with FIV

Feline immunodeficiency virus (FIV) DNA vaccine approaches that included a vif-deleted FIV provirus (FIV-pPPRDeltavif) and feline cytokine expression plasmids were tested for immunogenicity and efficacy by immunization of specific pathogen free cats. Vaccine protocols included FIV-pPPRDeltavif plasmid alone; a combination of FIV-pPPRDeltavif DNA and feline granulocyte macrophage-colony stimulating factor (GM-CSF) and tumor necrosis factor (TNF)-alpha expression plasmids; or a combination of FIV-pPPRDeltavif and feline interleukin (IL)-15 plasmids. Cats immunized with FIV-pPPRDeltavif, GM-CSF and TNF-alpha plasmids demonstrated an increased frequency of FIV-specific T cell proliferation responses compared to other vaccine groups. Immunization with FIV-pPPRDeltavif and IL-15 plasmids was distinguished from other vaccine protocols by the induction of antiviral antibodies. Suppression of virus loads was not observed for any of the FIV-pPPRDeltavif DNA vaccine protocols after challenge with the FIV-PPR isolate. However, prior immunization with FIV-pPPRDeltavif, GM-CSF, and TNF-alpha plasmids resulted in preservation of CD4 T cell functions, including mitogen-induced cytokine expression and antigen-specific proliferation upon infection with FIV. These findings justify further examination of cytokine combinations as adjuvants for lentiviral DNA vaccines.

Immune therapy for cancer

Over the past decade, immune therapy has become a standard treatment for a variety of cancers. Monoclonal antibodies, immune adjuvants, and vaccines against oncogenic viruses are now well-established cancer therapies. Immune modulation is a principal element of supportive care for many high-dose chemotherapy regimens. In addition, immune activation is now appreciated as central to the therapeutic mechanism of bone marrow transplantation for hematologic malignancies. Advances in our understanding of the molecular interactions between tumors and the immune system have led to many novel investigational therapies and continue to inform efforts for devising more potent therapeutics. Novel approaches to immune-based cancer treatment strive to augment antitumor immune responses by expanding tumor-reactive T cells, providing exogenous immune-activating stimuli, and antagonizing regulatory pathways that induce immune tolerance. The future of immune therapy for cancer is likely to combine many of these approaches to generate more effective treatments.

Treatment of mammary carcinomas in HER-2 transgenic mice through combination of genetic vaccine and an agonist of Toll-like receptor 9

PURPOSE

Oligodeoxynucleotides containing unmethylated CpG dinucleotides induce innate and adaptive immunity through Toll-like receptor 9 (TLR9). In the present study, we have examined the ability of a novel agonist of TLR9, called immunomodulatory oligonucleotide (IMO), to enhance effects of a HER-2/neu plasmid DNA electroporation/adenovirus (DNA-EP/Ad) vaccine.

EXPERIMENTAL DESIGN

BALB/NeuT mice were treated with DNA-EP vaccine alone, IMO alone, or the combination of two agents starting at week 13, when all mice showed mammary neoplasia. Tumor growth and survival were documented. Antibody and CD8+ T-cell responses were determined. Peptide microarray analysis of sera was carried out to identify immunoreactive epitopes. Additionally, microCT and microPET imaging was carried out in an advanced-stage tumor model starting treatment at week 17 in BALB/NeuT mice.

RESULTS

The combination of DNA-EP and IMO resulted in significant tumor regression or delay to tumor progression. 2-Deoxy-2-[18F]fluoro-D-glucose microPET and microCT imaging of mice showed reduced tumor size in the DNA-EP/IMO combination treatment group. Mice treated with the combination produced greater antibody titers with IgG2a isotype switch and antibody-dependent cellular cytotoxicity activity than did mice treated with DNA-EP vaccine. An immunogenic B-cell linear epitope, r70, within the HER-2 dimerization domain was identified through microarray analysis. Heterologous DNA-EP/Ad vaccination combined with IMO increased mice survival.

CONCLUSION

The combination of HER-2/neu genetic vaccine and novel agonist of TLR9 had potent antitumor activity associated with antibody isotype switch and antibody-dependent cellular cytotoxicity activities. These results support possible clinical trials of the combination of DNA-EP/Ad-based cancer vaccines and IMO.

Melanoma vaccines

Over the last century, vaccine studies have demonstrated that the human immune system, with appropriate help, can limit or prevent infection against otherwise lethal pathogens. Encouraged by these results, success in animal models and numerous well-documented reports of immune-mediated melanoma regression in humans, investigators developed melanoma vaccines. However, despite considerable laboratory evidence for vaccine-induced immune responses, clinical responses remain poor. Recent studies have elucidated several mechanisms that hinder or prevent the creation of successful vaccines and suggest novel approaches to overcome these barriers. Unraveling the mechanisms of autoimmunity, dendritic cell activation, regulatory T cells and Toll-like receptors will generate novel vaccines that, when used in conjunction with standard adjuvant therapies, may result in improved clinical outcomes. The objective of this review is to provide an overall summary of recent clinical trials with melanoma vaccines and highlight novel vaccine strategies to evaluate in the near future.

Immunomodulatory effects of phytocompounds characterized by in vivo transgenic human GM-CSF promoter activity in skin tissues

To investigate the immunomodulatory activities of phytocompounds for potential therapeutics, we devised an in vivo, transgenic, human cytokine gene promoter assay using defined epidermal skin cells as test tissue. Test compounds were topically applied to mouse skin before or after gene gun transfection, using a cytokine gene promoter-driven luciferase reporter. Croton oil, an inflammation inducer, induced transgenic GM-CSF and TNF-alpha promoter activities in skin epidermis 6-fold and 3.4-fold, respectively; however, it produced a less than 1.5-fold and 1.7-fold change in IL-1beta and IL-18 promoter activity, respectively. The phytocompound shikonin drastically inhibited inducible GM-CSF promoter activity. However, a fraction of Dioscorea batatas extract significantly increased the GM-CSF promoter activity in normal and inflamed skin. Shikonin suppressed the transcriptional activity of GM-CSF promoter by inhibiting the binding of TFIID protein complex (TBP) to TATA box. Our results demonstrate that this in vivo transgenic promoter activity assay system is cytokine gene-specific, and highly responsive to pro-inflammatory or anti-inflammatory stimuli. Currently it is difficult to profile the expression and cross-talk of various types of cytokines in vivo. This investigation has established a bona fide in vivo, in situ, immune tissue system for research into cytokine response to inflammation.

Lessons from randomized phase III studies with active cancer immunotherapies--outcomes from the 2006 meeting of the Cancer Vaccine Consortium (CVC)

After years of effort to develop active cancer immunotherapies, seven candidate products achieved promising results in phase I/II studies that triggered phase III randomized studies. One candidate to date has received an approvable letter from the United States Food and Drug Administration (FDA), defining a clear path to licensure for sipuleucel-T (Provenge, Dendreon) within the next couple of years. The other phase III studies failed to achieve statistical criteria for some or all of the critical endpoints. Yet, there is widespread recognition that using a patient's own immune system to target and destroy cancer cells may offer an effective biological therapy with less toxicity than presently available anti-cancer therapies, and several candidates are still being evaluated in clinical studies. This review summarizes the lessons learned from these case studies, evaluates scientific, study design, and business factors that can affect study outcomes, identifies common challenges faced by sponsors developing these innovative therapies, and provides considerations for future study designs that may increase the likelihood of success.

Cell based cancer vaccines: regulatory and commercial development

There is both clinical and regulatory drive to expedite development of safe, efficacious cancer therapies. Stimulation of the patients immune system through vaccination with tumour cells has long been at the vanguard of cancer therapeutic vaccines, and several have been demonstrated to be safe and to have efficacy in early clinical trials for a range of cancers including melanoma, renal cell carcinoma, prostate and colorectal cancers. A number of development-stage vaccines and strategies are currently being tested, utilising either autologous or allogeneic tumour cells, which may also have been ex vivo manipulated (e.g. cytokine transfected cells). It seems likely that clinical trial success, and hence patient benefit, could be improved through better patient identification, possibly by the discovery and use of novel immune response biomarkers. In this review, we aim to summarise the state of tumour cell vaccines in commercial development and to explore not only the difficulties of determining efficacy, but also the production challenges faced when developing a vaccine from proof of principle to pivotal phase III trials.