Therapeutic Vaccines

The idea of developing vaccines for Cancer is not so far fetched. Just as the immune system constantly works to protect the body from harmful viruses and bacteria, it also plays a vital role in protecting the body from cancer. Many cancerous cells express markers, called antigens, that act as targets for the immune system. In many cases, immune cells recognize the cancerous cells and destroy them. However, some cancerous cells are able to hide from the immune system or suppress it, or large numbers of cancerous cells simply overwhelm the immune system’s ability to clear the cells. The cancer cells are then able to divide and spread unchecked, damaging tissues and organs as they do. Today’s researchers are devising vaccines they hope will trigger the immune system to attack cancer cells reliably and effectively. They are also exploring other ways to boost the immune system’s response to cancerous cells. A therapeutic cancer vaccine, on the other hand, would be used to treat cancer after it has already appeared. There are two main types of such therapeutic vaccines: autologous vaccines and allogenic vaccines.

Autologous cancer vaccines: It is a personalized vaccine made from an individual’s own cells—either cancer cells or immune system cells. To make an autologous cancer cell cancer vaccine, cells from a person’s tumor are removed from the body and treated in a way that makes them a target for the immune system. They are then injected into the body, where immune cells recognize them, disable them and then do the same to other cancer cells in the body. Ideally, memory immune cells would persist in the body and be able to respond if cancer cells returned. The goal may be to treat the cancer present in the body or to prevent tumors from recurring after more conventional cancer treatments like surgery, radiation, or chemotherapy, have eliminated most or all of the cancer.

Allogenic cancer vaccines: They are made from non-self cancer cells grown in a lab.  Allogenic cancer vaccines are appealing because they are less costly to develop and produce than autologous vaccines. So far, none has been shown to be effective enough to be licensed.

Protein or Peptide Cancer Vaccines: The autologous and allogenic vaccines are whole-cell vaccines, that is, they are made from entire cancer cells or immune system cells. But some cancer vaccines in development are made from parts of cancer cells. These parts are proteins from cells, or even smaller components called peptides, which are sections of proteins. These proteins and peptides can be delivered as a vaccine alone, coupled with carriers such as viruses, or in combination with immune-stimulating molecules. As with most of the other therapeutic cancer vaccines, these protein or peptide vaccines for cancer are still in clinical trials.

DNA Vaccines: Another approach to therapeutic cancer vaccines uses DNA associated with tumor antigens to mount an immune response to an existing tumor. Generally, this involves vaccinating the cancer patient with a preparation containing DNA rings called plasmids. The plasmids, while not taken up into the patient’s own cellular DNA, prompt body cells to produce key tumor antigens. Those antigens then signal immune cells to start responding to similar antigens on existing cancer cells in the body.

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Source: https://www.historyofvaccines.org/content/articles/cancer-vaccines-and-immunotherapy