Keytruda (pembrolizumab) is an immunotherapy drug used to treat many types of cancer. Your doctor will use imaging, blood tests, and other laboratory tests to monitor whether the drug is working.
Keytruda and other immunotherapy drugs work by improving your immune system’s ability to identify and destroy cancer cells. Keytruda may be used alone or with other treatments, such as chemotherapy. Some of the cancers it’s approved to treat are:
- melanoma
- lung cancer
- head and neck squamous cell cancer
- esophageal cancer
- stomach cancer
Keytruda stimulates your immune system, causing it to attack cancer cells. More specifically, the drug blocks a certain protein on the surface of T cells, a type of white blood cell. This process helps your T cells find and destroy cancer cells.
Although Keytruda can help prevent the spread of cancer for some people, it’s not effective for everyone. During your Keytruda treatment, you’ll need to have regular follow-ups with your cancer team to assess whether the drug is working for you.
The main way your doctor can judge whether Keytruda is working is by ordering imaging tests to see whether the size of your tumor has changed.
In some cases, tumors can get larger before getting smaller. This is called
You’ll also receive regular blood tests before, during, and after your Keytruda treatment. These tests will help show whether your immune system activity has increased and assess your overall health. Often, these tests check for biomarkers that give your doctor important information about your cancer.
You may also have urine tests or other bodily fluid tests done to check for certain markers that indicate that your cancer might be improving.
The development of side effects such as inflammation can potentially suggest that Keytruda is changing your immune system activity. But some people may not have noticeable side effects, even if the drug is effective for them.
Immunotherapy drugs such as Keytruda are often slower to take effect than some other treatments, such as chemotherapy. This is because these drugs stimulate your immune system to attack cancer cells instead of destroying them directly.
Keytruda infusions are generally given every 3 to 6 weeks, depending on which condition they’re being used to treat. Research suggests that Keytruda takes about 16 weeks to reach peak concentration in your blood when it’s given every 3 weeks. So it may take several months for Keytruda to noticeably shrink your tumor.
Because of the way the drug works, you likely won’t notice it working in your body. But your doctor will order imaging tests to monitor whether the drug is effective at treating your cancer.
If you have questions about what to expect from your Keytruda treatment, talk with your doctor.
Keytruda is often used to treat advanced cancer that can’t be treated with surgery or chemotherapy. Because of this, the goal of Keytruda treatment is often to extend the amount of time your cancer remains stable.
Many studies have found that Keytruda can potentially help slow or reverse the progression of cancer when given by itself or with other treatments, such as chemotherapy.
For example, in a 2021 study of people with cervical cancer, researchers found that, compared with those who received only chemotherapy, more people who received pembrolizumab (the active ingredient in Keytruda) with chemotherapy had survived after 24 months. The survival rates were as follows:
- 53% among people given pembrolizumab and chemotherapy
- 41.7% among people given a placebo along with chemotherapy
Keytruda treatment usually lasts for up to 2 years. But some people may receive it longer if there’s evidence that it’s still effective and the side effects are minimal.
If Keytruda isn’t working for you or is causing unmanageable side effects, your doctor may recommend trying a different drug instead. They can discuss other treatment options with you. (To learn more about Keytruda’s side effects, see this article.)
If your doctor feels that your cancer isn’t likely to be well managed with Keytruda or other cancer treatments, they may recommend
Keytruda is used to treat many types of cancer. It’s often prescribed for advanced cancers that can’t be treated with surgery or chemotherapy.
Your doctor can check whether Keytruda is working by using certain scans or tests to monitor your cancer.
If you have other questions about what to expect with Keytruda treatment, talk with your doctor.
Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.