mRNA Vaccines

Scientists are studying whether vaccines made of mRNA may be useful in cancer treatment. Learn about mRNA vaccines, how they may help treat cancers, and what we know about their safety. 

Understanding mRNA

mRNA stands for “messenger RNA.” It is a natural part of our cells that carries a temporary set of instructions from part of our DNA (our genes). It tells the cell how to make a certain protein, and then it is broken down.

What mRNA does:

• Gives short-term instructions for the body to make a protein
• Works only in the outer part of the cell (not in the nucleus of the cell, where DNA lives)
• Breaks down within hours to days

What mRNA does NOT do:

• Does not affect your DNA, where your genes are
• Does not stay in your body long-term
• Cannot copy or spread on its own

Why mRNA matters in cancer

Using mRNA is a promising new way to make vaccines to help treat cancer.

Vaccines are substances that help your immune system learn to fight off something that doesn’t belong there. We’re most familiar with vaccines that help prevent some types of infections, such as the flu vaccine. But vaccines might also be helpful in treating cancer, if the vaccine can get the immune system to see and attack cancer cells. It's been hard to make effective cancer vaccines for several reasons, but mRNA might provide a way to make cancer vaccines that are more effective and easier to create.

mRNA vaccines for cancer treatment

When used as a vaccine, mRNA can be injected into the body packaged in tiny fat droplets. It finds its way into cells and gives them temporary instructions to make one or more proteins found on cancer cells. The immune system then learns to recognize those proteins as “flags” and attack the cancer cells that carry them.

mRNA vaccines might prove to be useful in several ways to treat cancer:

• Personalized vaccines: mRNA vaccines can be designed and made quickly, which is important because cancer cells can change frequently. Scientists may be able to design personalized mRNA vaccines that target unique properties of cancer cells, called “neoantigens,” before the cancer changes. The immune system can attack the cancer cells with neoantigens without harming normal cells. Each cancer has a unique mix of neoantigens, so a personalized approach may be useful.
• General vaccines: Some mRNA vaccines are made to target cancer proteins that many patients share, so they could help a wider group of people.
• Boosting other treatments: mRNA vaccines might be helpful when combined with other types of immunotherapy, such as checkpoint inhibitors.

Clinical trials are testing mRNA cancer vaccines in several types of cancer, including lung, breast, prostate, melanoma (skin), pancreatic, and brain cancers. Early results have been promising, but more research is still needed.

Are mRNA vaccines safe?

Each mRNA vaccine (or any other type of vaccine) has its own potential side effects.

So far, the only widely available mRNA vaccines have been used to help prevent COVID-19. The mRNA vaccines have been given to many people worldwide, and they’ve generally shown a good safety record. This has given doctors and scientists a lot of information about safety.

What we’ve seen so far:

• The most common reactions are short-term, such as soreness at the injection site, fatigue, or mild fever.
• Uncommon side effects, like heart inflammation in young men after COVID-19 vaccines, have been reported but remain rare.
• In cancer studies, the most common side effects are mild flu-like symptoms caused by the immune system becoming active.

How safety is checked:

• The manufacturing process is carefully controlled for purity and safety.
• New mRNA treatments need to go through several phases of clinical trials before approval.
• After approval, safety continues to be monitored worldwide.

Key points

• mRNA vaccines are a promising area of cancer treatment research.
• Although none have been approved at this time, they’re being studied for use against several types of cancer.
• mRNA vaccines can be made fairly quickly, which might allow for more personalized (and hopefully more effective) vaccines in the future.
• mRNA vaccines cannot change your DNA.
• mRNA vaccines cannot give you an infection.
• mRNA from a vaccine stays in the body for only a short time before it naturally breaks down.