At the beginning of October, the U.S. Food and Drug Administration (FDA) approved a drug combination to treat malignant pleural mesothelioma that cannot be otherwise removed by surgery. This approval is the first the FDA has made for a mesothelioma drug treatment regimen in 16 years. It is also the second-ever systemic therapy for mesothelioma approved by the FDA.
The newly approved drug combination includes nivolumab and ipilimumab. These drugs are both immunotherapy drugs developed by Bristol-Myers Squibb. Studies have shown that when used together, they can enhance T-cell function, which can lead to a decrease in tumor growth.
What do T-cells do?
T-cells are a type of white blood cell that plays a vital part in the body’s immune system. When they recognize a threat to the body, they become active and attack the threat. However, T-cells need a way to differentiate between healthy cells and cancerous ones.
To do this, T-cells have special proteins on their surface that act as receptors. Healthy cells have proteins that bind with the receptor on the T-cell. When this occurs, the T-cell becomes inactive and does not attack the healthy cell.
T-cells can also be inactivated by immune-regulating cells when the T-cells are not needed. The immune-regulating cells do this with proteins that bind with a different receptor on the T-cell.
How do the drugs help?
When someone has cancer, they may need more active T-cells than if they do not have cancer. However, some cancer cells can mimic healthy cells by developing the same protein that healthy cells use to turn off the T-cells. When cancer cells turn off T-cells, the body’s immune system may not properly fight cancer.
Nivolumab is also known by its brand name, Opdivo. It blocks the T-cell receptor that healthy cells and some cancerous cells use to inactivate the T-cell. With this receptor blocked, cancerous cells cannot mimic healthy cells.
Ipilimumab is also known by its brand name, Yervoy. It blocks the receptor that immune-regulating cells would use to inactivate the T-cell. This drug may also affect T-cells by helping some of them “remember” how to fight cancer cells, which can improve the body’s ability to fight cancer even after the treatment is complete.
Together, nivolumab and ipilimumab prevent T-cells from being inactivated. This can mean there are more active T-cells available to find and fight cancerous cells. However, this can have some drawbacks.
Are there risks to this drug regimen?
With its receptors blocked, T-cells may not be able to distinguish healthy cells from cancerous cells. As a result, active T-cells can attack healthy cells in the body during or after treatment.
When this happens, someone may experience various side effects, some of which can be very serious. Side effects could cause problems in someone’s lungs, intestines, liver, thyroid, pancreas, kidneys, skin, brain or other organs.
Despite the risks, this drug combination can offer hope for some people diagnosed with malignant pleural mesothelioma.
Mesothelioma is a particularly aggressive form of cancer, and it can develop decades after someone’s exposure to asbestos. Because of these traits, many people do not even realize that they are ill until cancer has reached an advanced stage.
This means that many people with a mesothelioma diagnosis have limited treatment options. The FDA’s approval of nivolumab and ipilimumab may offer those diagnosed with mesothelioma access to another potentially life-saving treatment option.