Mohamed Ibrahim Bassyouni
2021 / 9 / 7
Therapeutic vaccine in the treatment of cancer
When we say a vaccine against cancer, we mean an "immunotherapy" and not a "preventive vaccine", as is the case with most viruses. The concept of therapeutic vaccines is different. When a person hears the word vaccine, the idea of preventing a disease comes to mind. However, curative vaccines are the method of treatment. Like any other vaccine, the immune system is regulated against a specific type of target. The main goal is to enhance the activity of the immune system. This type of vaccine can be used to treat various types of diseases and viral infections. Efforts are being made to develop vaccines against many deadly diseases such as HIV, cancer, dengue fever, cholera, diphtheria, etc.
The therapeutic vaccine, that is, the one that does not aim to prevent the occurrence of the disease, but rather to treat it when it occurs. A therapeutic vaccine is a vaccine that is given after an illness´-or-injury has already occurred. The therapeutic vaccine works by activating the patient s immune system to fight infection. The therapeutic vaccine differs from the preventive vaccine in that the preventive vaccines are given to individuals as a precautionary measure to avoid infection´-or-disease, while the therapeutic vaccines are given after the individual has already contracted the disease´-or-infection. A therapeutic vaccine fights an infection already in the body rather than immunizing the body to protect against future diseases and infections. Therapeutic vaccines are mostly used against viral infections. Patients with chronic viral infections are given therapeutic vaccines, because their immune system is unable to produce enough effective antibodies. Sipuleucel-T, sold under the trade name Provenge and developed by Dendreon Pharmaceuticals LLC, is a cell-based immunotherapy for prostate cancer. It is an autologous cellular immunotherapy designed to stimulate a patient s immune system against cancer. It was the first therapeutic vaccine approved by the US Food and Drug Administration in 2010. This therapeutic vaccine helped treat prostate cancer as patients white blood cells (WBCs) were taken and treated with a drug (the vaccine) to train them to differentiate and fight cancer cells.
Therapeutic vaccines are a new form of vaccine that is mostly used for viral infections and various types of cancers. A therapeutic vaccine helps the immune system recognize a foreign agent such as a cancer cell´-or-virus. A specific type of therapeutic vaccine includes Antigen Vaccines. In the case of antigen vaccines, a foreign agent is introduced into the body to activate the immune system so that it recognizes the agent when it later encounters it.
There are two types of therapeutic vaccines:
Self means "derived from self". An autovaccine is a personal vaccine made from an individual s cells which can be either cancer cells´-or-immune system cells.
Allo means "other". Allogenic vaccines are basically cancer vaccines made from a different person s cancer cells that are grown in a laboratory.
Cancer is the leading cause of death in the modern era. Cancer types and stages have improved over time, as have cancer treatment efforts. Currently, there are about 369 cancer vaccine studies underway worldwide.
There are three therapeutic cancer vaccines approved by the US Food and Drug Administration, which are as follows-;-
Provenge is Sipuleucel-T, a dendritic cell-based vaccine for prostate cancer.
Bacillus Calmettle-Guerin (TheraCys) is a live attenuated vaccine that uses the Mycobacterium bovis strain for invasive bladder cancer.
Talimogene laherparepvec (T-VEC´-or-Imlygic) is an advanced melanoma vaccine.
We must know that vaccines against cancer are not new, but rather the search for them began more than thirty years ago, using RNA and viral vector techniques that were used to develop corona vaccines. Rapid development of these vaccines and testing them on millions of people will also allow to accelerate research on vaccines in the field of cancer. A few months ago, for example, Biontech began a clinical trial in humans using an RNA-based cancer vaccine. A few days ago, Oxford announced the start of a human trial for a vaccine against cancer that relies on the viral vector technology, after the vaccine, when used along with an immunotherapy for cancer, showed promising results in animals.
To understand the action of vaccines in cancer, we must first understand what cancer immunotherapy´-or-Immunotherapy is.
Immunotherapy does not involve attacking the disease itself, but rather re-dir-ecting the patient s immune system to fight the disease effectively by -dir-ecting CD8 killer T cells to the tumor.
The most common anti-PD1 immunotherapies are those that inhibit the PD-1 protein.
PD-1 is a protein found on the surface of T cells, and its binding to another protein, PDL-1, stops T cells from attacking the body s cells.
Unfortunately, cancer cells also largely have PDL-1 on their surface, which allows them to shut down the immune system and prevent T cells from attacking it.
Anti-PD1 immunotherapy prevents the cancer cell from misleading the immune system by blocking the association of PD-1/PDL1 and making T cells able to reactivate and attack the cancerous tumor, while this treatment was effective in many patients, and it was not shown to be effective in other patients. And it appeared that the reason was the insufficient number of T cells in these patients. The Oxford Cancer Vaccine aims to raise the number of killer T cells and provoke a strong immune response against cancer cells.
To this end, the vaccine specifically targets antigenes proteins found on the surface of cancer cells called MAGE. These proteins act as alarms that attract immune cells to the tumor, as the high number of these cells contributes to increasing the effectiveness of anti-PD1 immunotherapy.
Two points remain about MAGE proteins:
⁃-;- It is specifically present on the surface of cancer cells and not present in healthy cells, which allows to reduce the side effects of the immune system attack on healthy cells.
⁃-;- It is present in several types of cancer, allowing the treatment technique to be expanded to more than one type. The experiment with the immunotherapeutic vaccine in experimental animals showed good results as the tumor size decreased and the mice survived for a longer period.
There is no vaccine for HIV today, but therapeutic vaccines could be a breakthrough for HIV. Such vaccines would boost the immune system of infected patients to fight disease. Many researchers are trying to develop and test therapeutic HIV vaccines in order to slow the progression of HIV/AIDS. People with HIV usually have an undetectable level of HIV, which is detected with antiretroviral therapy (ART). If vaccines for HIV work, many lives will be saved. Several clinical trials of therapeutic HIV vaccines are being conducted, such as those conducted by AIDS info.
All of this could constitute a qualitative leap in the field of cancer treatment and the successful use of technologies in Corona vaccines will allow accelerating experiments and raising confidence in therapeutic vaccines in the hope that experiments will reach good results that improve our methods of treating cancer and provide patients with broader treatment options and a better quality of life.