Enhanced Immunogenicity of Engineered HER2 Antigens Potentiates Antitumor Immune Responses

For cancer vaccines, the selection of optimal tumor-associated antigens (TAAs) that can maximize the immunogenicity of the vaccine without causing unwanted adverse effects is challenging. In this study, we developed two engineered Human epidermal growth factor receptor 2 (HER2) antigens, K965 and K1117, and compared their immunogenicity to a previously reported truncated HER2 antigen, K684, within a B cell and monocyte-based vaccine (BVAC). We found that BVAC-K965 and BVAC-K1117 induced comparable antigen-specific antibody responses and antigen-specific T cell responses to BVAC-K684. Interestingly, BVAC-K1117 induced more potent antitumor activity than the other vaccines in murine CT26-HER2 tumor models. In addition, BVAC-K1117 showed enhanced antitumor effects against truncated p95HER2-expressing CT26 tumors compared to BVAC-K965 and BVAC-K684 based on the survival analysis by inducing T cell responses against intracellular domain (ICD) epitopes. The increased ICD epitope-specific T cell responses induced by BVAC-K1117 compared to BVAC-K965 and BVAC-K684 were recapitulated in human leukocyte antigen (HLA)-untyped human PBMCs and HLA-A*0201 PBMCs. Furthermore, we also observed synergistic antitumor effects between BVAC-K1117 and anti-PD-L1 antibody treatment against CT26-HER2 tumors. Collectively, our findings demonstrate that inclusion of a sufficient number of ICD epitopes of HER2 in cellular vaccines can improve the antitumor activity of the vaccine and provide a way to optimize the efficacy of anticancer cellular vaccines targeting HER2.Y

Bioprofiling TS/A Murine Mammary Cancer for a Functional Precision Experimental Model

The TS/A cell line was established in 1983 from a spontaneous mammary tumor arisen in an inbred BALB/c female mouse. Its features (heterogeneity, low immunogenicity and metastatic ability) rendered the TS/A cell line suitable as a preclinical model for studies on tumor-host interactions and for gene therapy approaches. The integrated biological profile of TS/A resulting from the review of the literature could be a path towards the description of a precision experimental model of mammary cancer

HER2/neu-specific Breast Cancer Vaccine

Breast cancer is the most common cancer among women. Of all breast cancers cases, approximately 30 percent have amplification of the self-antigen HER2/neu. Later studies demonstrated that HER2/neu-specific antibody and T cell responses were found in HER2/neu-positive breast cancer patients, indicating HER2/neu is a good target for active immunotherapy. A humanized anti HER2/neu antibody trastuzumab, was developed and found to be an effective therapy for HER2/neu. However, acquired antibody resistance occurs sooner or later in antibody treated patients. Such limitations of antibody therapy provoked scientists into the search for other therapeutic strategies. HER2/neu-targeted immunotherapeutic strategies, including vaccines using tumor lysates, protein/peptide, DNA, adenoviral vectors (AdV) and dendritic cells (DCs) pulsed with the above reagents, have been shown to be effective in experimental models. However, they have also been proven to be incapable of breaking tolerance towards HER2/neu in clinical trials and eliciting then have not elicited adequate antitumor immunity in curing HER2/neu positive breast cancer in transgenic mice with HER2/neu-specific immune tolerance, although both humoral and cellular immune responses could be detected. CD4+ helper T (Th) cells play crucial roles in priming, expansion and memory of both humoral and CD8+ cytotoxic T lymphocyte (CTL) responses. Therefore, they are essential in antitumor immunity. The tetanus toxoid Th epitope 947-967 P30, FNNFTVSFWLRVPKVSASHLE, has been found to be a universal epitope in sensitizing and proliferating CD4+ T cells ex vivo. OVA-P30 peptide vaccine could break CD8+ and CD4+ T cell tolerances against the neo-self-antigen OVA; it was able to protect transgenic rat insulin promoter (RIP)-mOVA mice from tumor growth. Adenovirus-based vaccines are able to induce high frequencies of transgene product-specific CD8+ T cell responses. In this study, we immunized C57BL/6 mice with OVA-expressing AdVOVA. We found that AdVOVA induced sustained OVA-specific CTL responses, leading to preventive antitumor immunity against OVA-expressing BL6-10OVA tumor cell challenge in wild-type C57BL/6 mice. In addition, we also immunized transgenic FVBneuN mice with neu-expressing AdVneu. We found that AdVneu vaccination induced neu-specific CTL responses, leading to partial reduction of breast carcinogenesis in FVBneuN mice. To assess whether the foreign Th epitope P30 enhances CD4+ and CD8+ T cell responses, we constructed another two recombinant AdVs (AdVOVA-P30 and AdVneu-P30), expressing OVA-P30 and HER2/neu-P30 gene, respectively. We transfected C57BL/6 mouse bone marrow dendritic cells (DCs) with AdVOVA and AdVOVA-P30 for preparation of DCOVA and DCOVA-P30 vaccines. We immunized C57BL/6 mice with DCOVA and DCOVA-P30 and then assessed CD4+ and CD8+ T cell responses and antitumor immunity subsequent to immunization. We demonstrated that both DCOVA and DCOVA-P30 were capable of stimulating both enhanced CD4+ and CD8+ T cell responses, leading to preventive antitumor immunity against challenge of OVA-expressing BL6-10OVA tumor in 100% (8/8) of the immunized mice. However, DCOVA-P30 induced more efficient CD4+ and CD8+ T cell responses than DCOVA, leading to significant reduction of growth of 3 day-established lung tumor metastasis in C57BL/6 mice, indicating that the foreign CD4+ Th epitope P30 can enhance both CD4+ and CD8+ T cell responses. In this study, we also transfected transgenic FVBneuN mouse bone marrow DCs with AdVneu and AdVneu-P30 for preparation of DCneu and DCneu-P30 vaccines. We immunized transgenic FVBneuN mice with DCneu and DCneu-P30 and then assessed CD4+ and CD8+ T cell responses and antitumor immunity subsequent to immunization. We demonstrated that DCneu-P30 but not DCneu was capable of stimulating both enhanced CD4+ and CD8+ T cell responses, leading to preventive antitumor immunity against challenge with 0.3×106 neu-expressing Tg1-1 tumor cells in 100% (8/8) immunized transgenic FVBneuN mice; this significantly reduced lung metastasis tumor colonies in immunized transgenic FVBneuN mice challenged with 1×106 Tg1-1 tumor cells, confirming that incooperation of foreign CD4+ Th epitope P30 into DC-based vaccines can at least partially break self-immune tolerance, leading to enhanced CTL responses and antitumor immunity in transgenic FVBneuN mice. Taken together, our data demonstrate that the CD4+ Th epitope P30 can enhance both CD4+ and CD8+ T cell responses, leading to enhanced DC-stimulated antitumor immunity. This may have impact in designing new DC-based vaccines for treatment of breast cancer and other types of human malignancies

Emerging immune-based technologies for high-grade gliomas

The selection of a tailored and successful strategy for high-grade gliomas (HGGs) treatment is still a concern. The abundance of aberrant mutations within the heterogenic genetic landscape of glioblastoma strongly influences cell expansion, proliferation, and therapeutic resistance. Identification of immune evasion pathways opens the way to novel immune-based strategies. This review intends to explore the emerging immunotherapies for HGGs. The immunosuppressive mechanisms related to the tumor microenvironment and future perspectives to overcome glioma immunity barriers are also debated

Use of single-chain antibody derivatives for targeted drug delivery

Single-chain antibodies (scFvs), which contain only the variable domains of full-length antibodies, are relatively small molecules that can be used for selective drug delivery. In this review, we discuss how scFvs help improve the specificity and efficiency of drugs. Small interfering RNA (siRNA) delivery using scFv-drug fusion peptides, siRNA delivery using scFv-conjugated nanoparticles, targeted delivery using scFv-viral peptide-fusion proteins, use of scFv in fusion with cell-penetrating peptides for effective targeted drug delivery, scFv-mediated targeted delivery of inorganic nanoparticles, scFv-mediated increase of tumor killing activity of granulocytes, use of scFv for tumor imaging, site-directed conjugation of scFv molecules to drug carrier systems, use of scFv to relieve pain and use of scFv for increasing drug loading efficiency are among the topics that are discussed here. © 2016, University of Michigan. All rights reserved

Immune-mediated mechanisms influencing the efficacy of anticancer therapies

Conventional anticancer therapies, such as chemotherapy, radiotherapy, and targeted therapy, are designed to kill cancer cells. However, the efficacy of anticancer therapies is not only determined by their direct effects on cancer cells but also by off-target effects within the host immune system. Cytotoxic treatment regimens elicit several changes in immune-related parameters including the composition, phenotype, and function of immune cells. Here we discuss the impact of innate and adaptive immune cells on the success of anticancer therapy. In this context we examine the opportunities to exploit host immune responses to boost tumor clearing, and highlight the challenges facing the treatment of advanced metastatic disease

MUC4 Based Immunotherapy for Pancreatic Cancer

Pancreatic Cancer (PC) is a lethal disease claiming approximately 45000 lives in the US in 2018, and it establishes an elaborate immunosuppressive tumor microenvironment that aids in disease pathogenesis. Immunotherapy has emerged as a strategy to target tumor cells by reprogramming patient’s immune system. Challenges present in PC immunotherapy are: i) identifying a tumor-associated antigen that could be targeted, ii) identifying adjuvants that could efficiently deliver antigens, iii) eliciting robust anti-tumor responses and iv) overcoming peripheral tolerance and immunosuppression elicited by the tumor. Firstly, we detected circulating autoantibodies to MUC4 present in PC patients and observed that IgM autoantibodies to MUC4 peptides significantly correlate with overall PC patient survival, thus suggesting that MUC4 could potentially be targeted for PC immunotherapy. Our group is the first to successfully purify recombinant MUC4β protein and characterize its immunogenic activity. We addressed the challenge of protein delivery by encapsulating MUC4β in novel polyanhydride nanoparticles (MUC4 nanovaccine). In the second part of the dissertation, we characterized MUC4 nanovaccine in both in vitro and in vivo system. Our studies showed that MUC4 nanovaccine could robustly activate dendritic cells (DCs) and induce secretion of Th1 cytokines in vitro. High levels of Th1 IgG2b anti-MUC4β antibodies were detected in MUC4 nanovaccine-immunized mice. As described in the third part of the dissertation, we observed that ex vivo T-cells activated by MUC4 nanovaccine-pulsed DCs showed enhanced cytotoxic killing of miniMUC4 tumor cells, when compared to soluble MUC4β mixed with empty nanoparticles (MUC4+NP). We validated our data in an in vivo subcutaneous PC tumor mouse model, and observed enhanced immune cells infiltration and corresponding levels of necrosis in miniMUC4 tumors corroborated with low tumor volume of miniMUC4 tumor (in comparison to contralateral vector control tumor) in MUC4-immunized mice. Furthermore, the presence of PD-L1 surface expression on miniMUC4 tumor cells indicated active immunosuppression lodged by tumor cells in response to IFNγ-secreting infiltrating cytotoxic T-cells. Taken together, studies in this dissertation demonstrate that MUC4 nanovaccine could serve as a potential strategy for PC immunotherapy

Oncolytic Virus Immunotherapy

Dear Readers, Oncolytic Viruses (OV) are self-propagating agents that can selectively induce the lysis of cancer cells while sparing normal tissues. OV-mediated cancer cell death is often immunogenic and triggers robust anticancer immune responses and immunoconversion of tumor microenvironments. This makes oncolytic virotherapy a promising new form of immunotherapy and OVs ideal candidates for combination therapy with other anticancer agents, including other immunotherapeutics. There are more than 40 OVs from nine different families in clinical development and many more at the preclinical stage. Each OV has its own unique characteristics, its pros and cons. Although herpes simplex virus is currently the lead clinical agent, a real champion among the OVs has not yet emerged, justifying the continuous development and optimization of these agents. This book, “Oncolytic Virus Immunotherapy”, summarizes the state-of-the-art and gives a comprehensive overview of the OV arena with a particular focus on new trends, directions, challenges, and opportunities

Emerging glyco-based strategies to steer immune responses

Glycan structures are common posttranslational modifications of proteins, which serve multiple important structural roles (for instance in protein folding), but also are crucial participants in cell-cell communications and in the regulation of immune responses. Through the interaction with glycan-binding receptors, glycans are able to affect the activation status of antigen-presenting cells, leading either to induction of pro-inflammatory responses or to suppression of immunity and instigation of immune tolerance. This unique feature of glycans has attracted the interest and spurred collaborations of glyco-chemists and glyco-immunologists to develop glycan-based tools as potential therapeutic approaches in the fight against diseases such as cancer and autoimmune conditions. In this review, we highlight emerging advances in this field, and in particular, we discuss on how glycan-modified conjugates or glycoengineered cells can be employed as targeting devices to direct tumor antigens to lectin receptors on antigen-presenting cells, like dendritic cells. In addition, we address how glycan-based nanoparticles can act as delivery platforms to enhance immune responses. Finally, we discuss some of the latest developments in glycan-based therapies, including chimeric antigen receptor (CAR)-T cells to achieve targeting of tumor-associated glycan-specific epitopes, as well as the use of glycan moieties to suppress ongoing immune responses, especially in the context of autoimmunity