Prophylactic cancer vaccination by targeting functional non-self

Nonviral oncogenic antigens and the inflammatory signals driving early cancer development as targets for cancer immunoprevention

Cancer immunoprevention is an emerging field that holds much promise. Within the past 20 years, prophylactic vaccines have been implemented on the population level for the immunoprevention of carcinomas induced by viruses, specifically hepatitis B virus (HBV) and human papillomavirus (HPV) infection. Armed with the success of prophylactic vaccines that prevent viral-induced tumors, the field must overcome its next hurdle: to develop robust prophylactic vaccines that prevent the remaining >80% of human cancers not induced by viral infection. In this review, we discuss some of the most promising non-virus-associated prophylactic vaccines that target endogenous neoantigens, including the earliest oncogene products, altered mucin 1 (MUC1) and α-enolase (ENO1), all of which produce new targets in the earliest stages of nonviral-induced tumorigenesis. We also highlight a novel attenuated Listeria monocytogenes-based vaccine expressing mutant oncogene Kras(G12D) (LM-Kras) effective in a pancreatic cancer model. A novel chimeric human/rat HER-2 plasmid vaccine (HuRT-DNA vaccine) effective in a breast cancer model is also discussed. In addition to prophylactic vaccine developments, this review highlights the potential use of classic drugs, such as aspirin and metformin, as chemopreventive agents that can potentially be used as adjuvants to enhance the anticancer immunogenicity and efficacy of noninfectious prophylactic vaccines by modulating the inflammatory pathways within the early tumor microenvironment (TME) that propels tumorigenesis. Finally, timing of prophylactic vaccine administration is critical to its immunopreventive efficacy, providing a necessary role of current and emerging biomarkers for cancer screening and early cancer detection.

Placenta-derived gp96 as a multivalent prophylactic cancer vaccine

A major challenge for designing prophylactic cancer vaccines is to define immunogenic and safe cancer antigens. Given the striking similarity of antigen expression patterns between cancer and embryonic tissues, we defined a prototype strategy of using placenta-derived heat shock protein gp96, which induces prophylactic anti-tumor T cell responses. Immunization with placental gp96 provided partial protection and long-term (at least 3 months) anti-tumor immunity against growth of transplantable melanoma or breast tumors in mice, elicited total protection against 7, 12-dimethylbenz(a)-anthracene (DMBA)-induced mammary tumors in rats, and significantly reduced the occurrence and growth of autochthonous breast tumors in HER2 transgenic mice. Placental gp96 activated HER2- and MUC1-specific T cell responses through binding to tumor-associated antigens. Our results reveal the novel immunogenicity of placental gp96 and its potential use as a multivalent cancer vaccine.

Could immunosignatures technology enable the development of a preventative cancer vaccine?

The exciting prospect of developing a universal prophylactic cancer vaccine now seems more possible due to advances in technology and basic knowledge. However, the problem of testing the efficacy of such a vaccine in a clinical trial seems daunting. The low incidence and long lead-time to diagnosis of cancer would make a standard clinical trial long and expensive. Recently, we demonstrated that the immunosignatures diagnostic technology could be useful in evaluating vaccines. The technology is based on profiling the antibody diversity in an individual on a peptide chip platform. Here we propose that this technology may also enable a clinical trial of a preventative vaccine. Preliminary evidence supports the prospect of immunosignatures detecting cancer at very early stages, well before conventional diagnosis. Because the technology is simple and inexpensive, it could be used to monitor the occurrence of cancer in participants and shorten the clinical trial.

Allergens are not pathogens: why immunization against allergy differs from vaccination against infectious diseases

Vaccination against infectious diseases has been one of the major breakthroughs in human medical history, saving the lives of millions of people each year. More recently, prophylactic vaccination against non-infectious diseases such as cancer, Alzheimer’s disease, diabetes, and type I allergy is being investigated. Particularly in case of IgE-driven allergic disorders, which afflict almost a quarter of the population in highly developed countries, preventative measures would represent a major improvement for patients’ health as well as an economic relief for public health services. As an alternative to allergen-specific immunotherapy, prophylactic vaccination against type I allergic diseases could slow down or even stop the progress of the allergy pandemic. Allergen-encoding gene-based vaccines, i.e., plasmid DNA and mRNA vaccines, provide the advantage of purity over crude allergen extracts, which involve the risk of de novo sensitizations. Furthermore, these formulations have been demonstrated to induce T helper 1 as well as T regulatory immune responses—a pre-requisite for prophylactic intervention against allergies. However, prophylactic vaccines against environmental allergens strikingly differ from conventional vaccines against infectious diseases or therapeutic approaches concerning the underlying immunological mechanisms.

Potential use of vaccines in the primary prevention of breast cancer in high-risk patients

Cancer vaccines are an emerging therapeutic and prophylactic modality that may play a more important role in cancer prevention and treatment in the future. Therapeutic cancer vaccines are designed to generate a targeted, immune-mediated antitumor response. Successful prophylactic vaccines are those against oncogenic viral infections, such as the human papillomavirus and cervical cancer. However, a tough challenge for the majority of tumor vaccines is the self-nature of tumor antigens. Ongoing studies are investigating methods to enhance vaccine strategies including immune-modulating agents. The present review analyzes the potential use of vaccines in the primary prevention of breast cancer, focusing on the recent extension of vaccine target selection to self-proteins that are overexpressed during the early stages of tumor development but whose expression no longer occurs as we age, a feature that may avoid clinically significant autoimmune sequelae.

Experimental autoimmune breast failure: a model for lactation insufficiency, postnatal nutritional deprivation, and prophylactic breast cancer vaccination

Mastitis is a substantial clinical problem in lactating women that may result in severe pain and abrupt termination of breastfeeding, thereby predisposing infants to long-term health risks. Many cases of mastitis involve no known infectious agent and may fundamentally be due to autoimmune-mediated inflammation of the breast. Herein, we develop a murine model of autoimmune mastitis and provide a detailed characterization of its resulting phenotype of breast failure and lactation insufficiency. To generate breast-specific autoimmunity, we immunized SWXJ mice with recombinant mouse α-lactalbumin, a lactation-dependent, breast-specific differentiation protein critical for production of lactose. Mice immunized with α-lactalbumin showed extensive T-cell-mediated inflammation in lactating normal breast parenchyma but none in nonlactating normal breast parenchyma. This targeted autoimmune attack resulted in breast failure characterized by lactation insufficiency and decreased ability to nurture offspring. Although immunization with α-lactalbumin had no effect on fertility and birth numbers, pups nursed by α-lactalbumin-immunized mice showed significantly disrupted growth often accompanied by kwashiorkor-like nutritional abnormalities, including alopecia, liver toxicity, and runting. This experimental model of autoimmune breast failure has useful applications for prophylactic breast cancer vaccination and for addressing inflammatory complications during breastfeeding. In addition, this model is suited for investigating nutritionally based "failure-to-thrive" issues, particularly regarding the long-term implications of postnatal nutritional deprivation.