Prolongation of the survival of breast cancer-bearing mice immunized with GM-CSF-secreting syngeneic/allogeneic fibroblasts transfected with a cDNA expression library from breast cancer cells

Recent Progress on Therapeutic Vaccines for Breast Cancer

Breast cancer remains the most frequently diagnosed malignancy worldwide. Advanced breast cancer is still an incurable disease mainly because of its heterogeneity and limited immunogenicity. The great success of cancer immunotherapy is paving the way for a new era in cancer treatment, and therapeutic cancer vaccination is an area of interest. Vaccine targets include tumor-associated antigens and tumor-specific antigens. Immune responses differ in different vaccine delivery platforms. Next-generation sequencing technologies and computational analysis have recently made personalized vaccination possible. However, only a few cases benefiting from neoantigen-based treatment have been reported in breast cancer, and more attention has been given to overexpressed antigen-based treatment, especially human epidermal growth factor 2-derived peptide vaccines. Here, we discuss recent advancements in therapeutic vaccines for breast cancer and highlight near-term opportunities for moving forward.

The Role of the Tumor Microenvironment in Developing Successful Therapeutic and Secondary Prophylactic Breast Cancer Vaccines

Breast cancer affects roughly one in eight women over their lifetime and is a leading cause of cancer-related death in women. While outcomes have improved in recent years, prognosis remains poor for patients who present with either disseminated disease or aggressive molecular subtypes. Cancer immunotherapy has revolutionized the treatment of several cancers, with therapeutic vaccines aiming to direct the cytotoxic immune program against tumor cells showing particular promise. However, these results have yet to translate to breast cancer, which remains largely refractory from such approaches. Recent evidence suggests that the breast tumor microenvironment (TME) is an important and long understudied barrier to the efficacy of therapeutic vaccines. Through an improved understanding of the complex and biologically diverse breast TME, it may be possible to advance new combination strategies to render breast carcinomas sensitive to the effects of therapeutic vaccines. Here, we discuss past and present efforts to advance therapeutic vaccines in the treatment of breast cancer, the molecular mechanisms through which the TME contributes to the failure of such approaches, as well as the potential means through which these can be overcome.

Novel Immunotherapeutic Approaches for Head and Neck Squamous Cell Carcinoma

The immune system plays a key role in preventing tumor formation by recognizing and destroying malignant cells. For over a century, researchers have attempted to harness the immune response as a cancer treatment, although this approach has only recently achieved clinical success. Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide and is associated with cigarette smoking, alcohol consumption, betel nut use, and human papillomavirus infection. Unfortunately, worldwide mortality from HNSCC remains high, partially due to limits on therapy secondary to the significant morbidity associated with current treatments. Therefore, immunotherapeutic approaches to HNSCC treatment are attractive for their potential to reduce morbidity while improving survival. However, the application of immunotherapies to this disease has been challenging because HNSCC is profoundly immunosuppressive, resulting in decreased absolute lymphocyte counts, impaired natural killer cell function, reduced antigen-presenting cell function, and a tumor-permissive cytokine profile. Despite these challenges, numerous clinical trials testing the safety and efficacy of immunotherapeutic approaches to HNSCC treatment are currently underway, many of which have produced promising results. This review will summarize immunotherapeutic approaches to HNSCC that are currently undergoing clinical trials.

Vaccine immunotherapy in breast cancer treatment: promising, but still early

Cancer vaccine-based immunotherapy should potentiate immunosurveillance function, preventing and protecting against growing tumors. Tumor cells usually activate the immune system, including T lymphocytes and natural killer cells, which are able to eliminate the transformed cells. Immunosubversion mechanisms related to tumor cells antigenic immunoediting induces mechanisms of tolerance and immunoescape. This condition impairs not only host-generated immunosurveillance, but also attempts to harness the immune response for therapeutic purposes. Most trials evaluating breast cancer vaccines have been carried out in patients in the metastatic and adjuvant setting. The aim of this review is to analyze the activity of vaccination strategies in current clinical trials. We summarize the differential approaches, protein-based and cell-based vaccines, focusing on vaccines targeting HER2/neu protein. Another focus of the review is to provide the reader with future challenges in the field, taking into account both the immunological and clinical aspects to better target the goal.

Enhancing cellular cancer vaccines

Various strategies have been used to generate cellular cancer vaccines with the expectation that they will become an effective part of the overall management of cancer patients. However, with few notable exceptions, immunization has not resulted in significant long-term therapeutic benefits. Tumor growth has continued and patient survival has been at best only modestly prolonged. One possible explanation is that as only a small proportion of the constituents of malignant cells are "tumor specific" and the vast majority are the products of nonantigenic, normal "housekeeping" genes, the immune response in patients immunized with cellular cancer vaccines is not sufficient to result in tumor rejection. Here, we review and characterize various types of cellular cancer vaccines. In addition, in a mouse breast cancer model system, we describe a unique strategy designed to enrich cellular vaccines for cells that induce tumor immunity. Numerous advantages and disadvantages of cancer immunotherapy with cellular vaccines are also presented.

Gene transfer of AIMP1 and B7.1 into epitope-loaded, fibroblasts induces tumor-specific CTL immunity, and prolongs the survival period of tumor-bearing mice

T helper type 1 (Th1) cell-mediated immune responses play various roles in cellular immunity, including inducing cytotoxic T lymphocytes (CTLs) and they have been shown to be crucial in cancer immunotherapy. Previously, we found that aminoacyl-tRNA synthetase-interacting multifunctional protein 1 (AIMP1) stimulated antigen-presenting cells to secrete IL-12, leading to enhanced Th1 cell responses. In this study, as a way of enhancing antigen-specific Th1 responses, mouse fibroblasts (H-2(b)) were genetically modified to express an AIMP1 and a costimulatory B7.1 (Fb/AIMP1/B7.1). Fb/AIMP1/B7.1 cells were then loaded with an ovalbumin epitope as a model antigen (Fb/AIMP1/B7.1/OVA), and tested to determine if they induced OVA-specific CTLs in C57BL/6 mice (H-2(b)). Immunization with Fb/AIMP1/B7.1/OVA cells induced strong cytotoxic activities against OVA-expressing EG7 tumor cells, but not against other H-2(b) tumor cells. The levels of the cytotoxic response in the immunized mice with Fb/AIMP1/B7.1/OVA cells were significantly higher than the responses in mice immunized with other cell constructs. CD8(+) T cells were a major cell-type of OVA-specific antitumor immunity induced by Fb/AIMP1/B7.1/OVA cells. Furthermore, treatment with Fb/AIMP1/B7.1/OVA cells significantly prolonged the survival period of EG7 tumor-bearing mice. These results indicate that AIMP1-secreting, epitope-loaded fibroblasts efficiently induce antigen-specific CTL responses in mice.

T-regulatory cells are relatively deficient in squamous carcinomas undergoing regression in mice immunized with a squamous carcinoma vaccine enriched for immunotherapeutic cells

In a prior report (Int J Cancer 2006; 119: 339-348), we described a new vaccination strategy for squamous cell carcinoma (SCC). The vaccine was prepared by transfer of unfractionated DNA-fragments (25 kb) from KLN205 cells, a squamous carcinoma cell line (DBA/2 origin; H-2(d)) into LM cells, a highly immunogenic mouse fibroblast cell line (C3H/He origin; (H-2(k))). As only a small proportion of the transfected cell population was expected to have incorporated DNA segments that included genes specifying antigens associated with the squamous carcinoma cells, we devised a novel strategy to enrich the vaccine for immunotherapeutic cells. Enhanced immunity to squamous carcinoma was induced in tumor-bearing mice treated solely by immunization with the enriched vaccine, which translated into prolonged survival without toxicity. Here, we describe the characteristics of the cell populations infiltrating established squamous carcinomas undergoing regression in mice immunized with vaccines enriched for immunotherapeutic cells. The results indicated that CD8+ T cells were predominant and that T-regulatory cells (FoxP3+, CD4/CD25+, CD4/CD62L(high), CD4/CTLA-4e) were relatively deficient in the regressing tumors. Inflammatory infiltrates were not detected in various organs and tissues of mice immunized with the DNA-based vaccine.