For many years, scientists and researchers have searched for a cure for cancer. Several technological advancements have been made and there are a variety of therapies available. While there is no cure for cancer, there are treatments that may cure individuals with cancer. Cancer vaccines have been a large area of interest for treatment with the first preventive vaccine being approved in 1981 and the first therapeutic vaccine being approved in 1990. Now, over 40 years later, ongoing research is being conducted to find vaccines for cancer treatment in various fields. This blog post delves into how therapeutic cancer vaccines work, what options are currently available, and what the future looks like in our ongoing fight against curing cancer.
How Therapeutic Cancer Vaccines Work
Antigens are located on cell surfaces and are perceived by the body as potentially harmful substances. Consequently, the immune system targets and attacks antigens to eliminate them. This process results in the immune system developing a “memory” that aids in fighting future antigens. Therapeutic cancer vaccines enhance the immune system’s ability to find and destroy antigens. Cancer cells contain cancer-specific antigens on their surface that healthy cells lack. When a vaccine with these molecules is administered to a patient, the molecules act as antigens that tell the immune system to find and destroy the cancer cells.
Some cancer vaccines are tailored for a specific person, referred to as personalized vaccines. This type of vaccine is produced from samples of a person’s tumor removed during surgery. To some degree, each person’s tumor is unique and has its own distinguishable antigens. These tumors display unique targets due to mutations referred to as neoantigens. They are exclusively expressed by tumor cells, not a patient’s healthy cells. Personalized neoantigen vaccines can, in theory, directly target a patient’s tumor cells and generate an immune response while sparing healthy cells. This would also potentially help reduce side effects from an immune attack.
Most cancer vaccines are exclusively accessible via participation in clinical trials involving volunteer investigative studies. However, there are currently two FDA-approved vaccines for cancer treatment.
Current Vaccines for Cancer Treatment
Bacillus Calmette-Guérin (BCG): This vaccine stimulates the immune system by using weakened bacteria. It is approved for patients with early-stage bladder cancer.
Sipuleucel-T (Provenge®): This vaccine is made from a patient’s own stimulated dendritic cells, which are a type of immune cell that presents antigens on its surface to enhance immune responses. It is currently approved for prostate cancer.
Like any treatment, there are side effects associated with cancer vaccines that vary based on the type of cancer vaccine, what the vaccine targets, the location and type of cancer, and a patient’s overall health. Side effects may be due to a misdirected immune response in which the immune system targets healthy cells that express the same target proteins. Some common side effects of the current FDA-approved cancer vaccines include chills, fever, and joint aches, among others.
Challenges of Using Treatment Vaccines
Creating vaccines for cancer treatment is difficult for a multitude of reasons. The most prominent reason is that cancer cells weaken and suppress the immune system. This is what allows cancer to thrive in the first place, and scientists are currently testing the input of substances to improve the body’s immune response. Similarly, sick and elderly people have weak immune systems.
Their bodies cannot produce as strong immune responses after vaccine administration as a younger and healthy person. This, along with alternative cancer treatments weakening an individual’s immune system, limits how well a vaccine can work. Additionally, cancer cells come from a person’s healthy cells. Some cancer cells may not appear harmful to the immune system and will be ignored by the cells rather than attacked. Furthermore, large or more advanced tumors are more difficult to get rid of than small, less-developed tumors. Vaccines may not be sufficient to combat cancers of this size and may be given in conjunction with other treatments.
Cancer Vaccine Clinical Trials
Several vaccine targets for various cancers are presently being investigated in clinical trials. Some cancers include bladder, breast, kidney, lung, pancreatic, and prostate cancer, along with brain tumors, leukemia, melanomas, and myelomas. Both treatment and preventive vaccines are being tested and looking to help treat cancers at various stages. Most cancer vaccines are still in the clinical trial phase, but there are hopes that there may one day be a breakthrough. With the two vaccines for cancer treatment available, future ones are an inevitability even though it may be years until we see the next approved one.
Conclusion
The future for developing new cancer vaccines is bright. With new technology and ongoing clinical trials, research is progressing at an incredible rate. Personalized vaccines, combination therapies, and technological advancements are some of the many ways we are tackling beating cancer for good. While many challenges lie ahead, the ongoing research and collaborative efforts of scientific and medical professionals around the world are charging a way forward into a more cancer-free future.
