Cancer vaccines -2

Q: What is Cervavac? Is it really useful?

Krishna: Cervavac is a preventive vaccine. This is actually a vaccine aginst human papillomavirus (HPV) that causes cancer.

Cancer vaccines exist both to prevent different types of cancer and to treat them. 

Vaccines train the body’s immune system to fight disease.

There are two types of cancer vaccines. One targets the viruses that can cause cancer. This will only work if a person receives them before they have exposure to the virus.

Vaccines that prevent cancer work by training the immune system to recognize and destroy the viruses that can lead to cancer. 

Some cancers are caused by viruses. Vaccines that help protect against infections with these viruses might also help prevent some of these cancers.

Doctors can also use some vaccines to treat some types of cancer. These tend to help stop the cancer from coming back or from spreading.

Vaccines that treat cancer work by training the immune system to recognize and destroy cancer cells. 

Vaccines to prevent cancers:

Some viruses can cause certain types of cancer. Vaccines to prevent cancer work by helping the body fight the virus.

Immune cells are part of the body’s defense against harmful molecules, such as viruses. Each immune cell has proteins, called immune receptors, on its surface. Viruses also have proteins on their surface. These are called antigens.

Receptors and antigens are unique to each immune cell and each virus. They fit together like a lock and key. When an immune cell finds the antigen that “fits” in its lock, it binds to it and destroys the virus.

Sometimes, the body might not have immune cells with the right receptors to fight the virus. Vaccines to prevent cancer work by training the immune cells to recognize the virus.

Examples of cancer preventing vaccines: HPV vaccine, Hepatitis B vaccine

Cervavac is an Indian-made low cost HPV vaccine.

Vaccines to treat cancer: 

Cancer treatment vaccines are different from the vaccines that work against viruses. These vaccines try to get the immune system to mount an attack against cancer cells in the body. Instead of preventing disease, they are meant to get the immune system to attack a disease that already exists.

Some cancer treatment vaccines are made up of cancer cells, parts of cells, or pure antigens (certain proteins on the cancer cells). Sometimes a patient’s own immune cells are removed and exposed to these substances in the lab to create the vaccine. Once the vaccine is ready, it’s injected into the body to increase the immune response against cancer cells.

Vaccines are often combined with other substances or cells called adjuvants that help boost the immune response even further.

Cancer vaccines cause the immune system to attack cells with one or more specific antigens. Because the immune system has special cells for memory, it’s hoped that the vaccine might continue to work long after it’s given.

Like viruses, cancer cells also have antigens on their surface. However, immune cells do not usually have the right receptors to bind to them. Vaccines to treat cancer tend to work by helping the immune system find, bind to, and destroy cancer cells.

Vaccines for cancer treatment can: prevent cancer from returning, kill cancer cells that have remained in the body following treatment, prevent a tumor from growing or spreading.

Doctors can use vaccines alongside other cancer treatments, such as chemotherapy.

Current cancer-treating vaccines in the world.  So far, the FDA(US) have only approved the following vaccines

BCG live: This vaccine can treat early stage bladder cancer.

Sipuleucel-T: This vaccine can treat prostate cancer that is no longer being helped by hormone therapy. Side effects  are usually mild and can include fever, chills, fatigue, back and joint pain, nausea, and headache. A few men may have more severe symptoms, including problems breathing and high blood pressure.

Talimogene laherparepvec (T-VEC): This vaccine can treat advanced  melanoma skin cancer. It is made from a herpes virus that has been altered in the lab to produce a substance that the body normally produces, called a cytokine. This cytokine boosts the immune system and can cause flu-like symptoms for a short time.

Vaccines to treat cancer must cater to an individual’s needs. Scientists build each medicine to target the antigens on that person’s particular cancer cells.

Researchers are currently studying more possible vaccines for many types of cancer, including: lung cancer, brain tumors, breast cancer, pancreatic cancer, bladder cancer, myeloma , melanoma. colorectal cancer, kidney cancer, leukemia, and cervical cancer.

Main challenges the researchers face while developing the cancer vaccines:

Developing cancer vaccines is difficult for a number of reasons. The list below will look at these in more detail.

• Weakened immune systems: Cancer cells are able to grow because they suppress the immune system. This means that immune cells are weaker and more difficult to train.
• Tumor size: A vaccine cannot always treat a larger or more advanced tumor on its own. Doctors may need to provide other forms of treatment alongside the vaccine.
• The appearance of the cells: Cancer develops when the body’s own cells start to multiply uncontrollably. This means that cancer cells can look just like normal cells to the body’s immune system. Therefore, it may not always attack cancer cells.
• Unpredictable responses: Older adults and people who are sick have weakened immune systems. This means that their bodies might not be able to respond to a vaccine as well as they need to.

There are several other vaccines that are undergoing trials across the world.

You will find another article on the same topic here: https://kkartlab.in/group/some-science/forum/topics/cancer-vaccines