Since the development of the first vaccine more than two centuries ago, vaccines have successfully helped save hundreds of millions of lives against some of the deadliest viral and bacterial diseases in the 20th century. Some of these diseases include polio, measles, smallpox, diphtheria, tetanus, and tuberculosis.
Vaccines work by exposing a person to the inactivated or weakened version of the virus or bacteria. This allows the person’s immune system to identify these threats based on their specific markers called “antigens” and develop a response against them. Ideally, these are administered to individuals who have not been infected yet by the virus or bacteria.
In the case of cancer, the development of preventive and therapeutic cancer vaccines is more difficult because cancer cells closely resemble normal healthy cells, unlike viruses and bacteria which appear foreign to the immune system. Additionally, each person’s tumor is unique and contains its own distinct antigens, requiring more complicated approaches to develop effective cancer vaccines. To know more about cancer vaccines, check out Treatment Vaccines in the Fight Against Cancer.
What kinds of preventive cancer vaccines are available?
At present, there are two types of preventive cancer vaccines approved by the U.S. Food and Drug Administration. These are:
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- HPV vaccine – This vaccine targets the human papillomavirus (HPV), which may cause the development of cervical, vaginal, and anal cancers if it stays in the body for a long time. Although HPV can cause other types of cancer such as oral cancer, the FDA has still not approved the use of HPV vaccine for these diseases.
- Hepatitis vaccine – This vaccine can help prevent the development of Hepatitis B-related liver cancer.
For other types of cancer such as breast cancer, there are still no FDA-approved preventive vaccines yet. However, studies are being conducted to design a preventive vaccine against breast cancer. The vaccine aims to target antigens that are expressed during breast cancer initiation. According to a 2022 article entitled “New generation of cancer-preventing vaccines could wipe out tumors before they form”, the National Breast Cancer Coalition is poised to test breast cancer preventive vaccines for healthy people who have high genetic risk factors for the disease.
This area of study is very important because breast cancer remains the most freuently diagnosed cancer in the US, affecting 2.3 million women globally in 2020.
What are the kinds of therapeutic vaccines available?
Despite advancements in cancer treatments like chemotherapy, endocrine therapy, and HER2 targeted therapy in the past decades, there is still a great challenge in preventing metastasis and relapse of breast cancer. Since breast cancer is immunologic, cancer vaccine is a promising option to control the progression of breast cancer as it aims to induce durable immunologic response to eradicate tumor cells.
There are different types of therapeutic vaccines for breast cancer based on platforms and formulations.
- Peptide vaccine – This vaccine is more widely used because short amino acid peptides are easy and cheap to manufacture and transport.
- Protein-based vaccine – Developed with an amino acid sequence longer than peptide, this vaccine has a less efficient presentation proces. The response is also difficult to measure because of lack of a specific marker.
- Carbohydrate antigen vaccine – Unlike the first two vaccines, this vaccine identifies carbohydrate antigens abnormally expressed by tumor cells.
- Tumor cell vaccine – This vaccine uses whole tumor cells or products of tumor cell lysis to activate an immune response. Its disadvantage is that it lacks a standardized method for tumor cell preparation and may cause an autoimmune reaction.
- DNA-based vaccine – Using the DNA sequence encoding tumor antigens, this vaccine enables the immune cells to stimulate an antigen-specific immunity. Despite its low cost production and storage, it has weak immunogenicity due to low efficiency of antigen expression and plasmids uptake.
How effective is breast cancer therapeutic vaccine?
As of the moment, clinical trials on the evaluation of the effectiveness of breast cancer vaccines have demonstrated promising results. Researchers from the University of Washington School of Medicine reported in a study published in 2022 by JAMA Oncology that the Phase I experimental vaccine safely generated a strong immune response to a key breast tumor protein. This result, however, requires further evaluation in a larger, randomized clinical trial.
Despite the successful induction of immune responses, clinical trials such as this have not provided enough evidence of clinical benefits as waning of the immunity over time was observed, resulting in increased recurrences. A potential explanation to date for this is that the effective immunity against tumors stimulated by vaccines is only short-term to contribute to survival.
Moving forward, researchers are looking into investigating factors such as optimal immunization dose and schedule, delivery routes, and options for immunologic boosters as part of their next steps. They will also consider combining cancer vaccines with immune checkpoint blockade or anti-HER2 monoclonal antibodies. The HER2 (human epidermal growth factor receptor 2) protein, at high levels, is the one that triggers quick growth of cancer cells.
Are there any potential side effects of breast cancer vaccines?
In the same study by the group of researchers from the University of Washington School of Medicine, the experimental vaccines did not trigger severe side effects. The most common side effects observed among the 66 women subjects were swelling and redness in the injection site, fever, chills and other flu-like symptoms.
