Reviewed and edited by: Danielle Leonardo, M.D. Medical Oncologist

Mesothelioma is a cancer with a poor prognosis, but immunotherapy can help people with the disease live longer. Immunotherapy makes your immune system stronger against diseases, and it’s being studied as a way to treat mesothelioma.

Tumor-infiltrating lymphocyte (TIL) therapy is a type of immunotherapy that makes use of your best cancer-fighting cells. You have cells called lymphocytes inside you that can fight mesothelioma tumors, and this is what TIL therapy focuses on.

What are lymphocytes?

Lymphocytes are part of your immune system. These cells fight harmful things in your body such as mesothelioma tumors. Lymphocytes first have to find and recognize mesothelioma cells. Then they go into the tumor and start destroying tumor cells.

It’s similar to an army of soldiers on a mission to destroy an enemy. The soldiers have to fight the enemy, but first they need to know how to find and recognize them. TIL therapy works the same way.

How does TIL therapy work?

When you have a large army of soldiers, some of them will be more skilled than others. The ones who can find and kill the enemy fastest are the strongest, most elite soldiers.

What if you could clone these elite soldiers so there were more of them to go after the enemy? That’s the goal of TIL therapy. This treatment involves cloning your best lymphocytes to go after cancer cells.

First, the mesothelioma tumor is taken out through surgery. Then doctors look inside the tumor and find lymphocytes that are there fighting tumor cells. These lymphocytes are cloned, activated, then put back into your body so they can keep fighting cancer.

The idea is that the lymphocytes inside the tumor are the best lymphocytes, because they were the ones able to find the tumor cells fastest. That’s why doctors want to clone these lymphocytes instead of ones that haven’t reached the tumor. This is where the name tumor-infiltrating lymphocytes comes from.

How well does TIL therapy work against mesothelioma?

There aren’t many studies yet about how well TIL therapy works against mesothelioma. It’s hard to say for sure that it’s a strong treatment. The good news is that so far, studies have shown that TIL therapy did reduce tumors in some people.

What are the side effects of TIL therapy?

The side effects of this therapy are hard to predict. Different people have different experiences. Talk with your healthcare provider if any side effects happen to you.

The most common side effects of TIL therapy are:

  1. Infusion-related reactions: When lymphocytes are infused back into your body, you may have allergic or hypersensitivity reactions like fever, chills, low blood pressure, or trouble breathing. Your health care team will manage these reactions.
  2. Cytokine release syndrome (CRS): Cytokine release syndrome causes inflammation in multiple parts of your body. You may get a fever, fatigue, muscle aches, and in severe cases, organ problems. Intensive treatments may be needed.
  3. Immune-related adverse events (iRAE’s): Like other immunotherapies, TIL therapy can lead to immune-related adverse events. This means your immune system becomes too active and hurts healthy cells in your body, causing inflammation. Your lungs, liver, colon, or other organs can be affected, and you may need medical intervention.

TIL therapy uses your immune system to reduce mesothelioma tumors. Lymphocytes in your immune system can find and destroy tumor cells. Some lymphocytes are able to find tumor cells faster than others, so doctors want to clone those lymphocytes because they’re the best ones. When those lymphocytes are put back into your body, they can fight tumors better.

More research needs to be done about TIL therapy. It may not work for everyone, and the side effects can be hard to predict. But this treatment looks like it has potential. TIL therapy may help people with mesothelioma have longer lives.