Keytruda (pembrolizumab) is an immunotherapy drug used to treat many types of cancer, including melanoma, lung cancer, and stomach cancer. Your doctor will use imaging, blood tests, and other laboratory tests to monitor whether this drug is working.
Keytruda and other immunotherapy drugs work by improving your immune system’s ability to identify and destroy cancer cells. This medication may be used alone or with other treatments, such as chemotherapy.
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.
Keep reading about ways to know whether Keytruda is effective for your condition.
Your doctor will use imaging tests, blood tests, and other laboratory tests to monitor whether Keytruda is working.
Imaging tests
Your doctor will monitor how well Keytruda is working for your condition by checking the size of your tumor with imaging tests such as a CT or an MRI scan. These scans are the main way your doctor can judge whether Keytruda is effective.
In some cases, tumors can get larger before getting smaller, which is known as
Lab tests
Blood tests and other lab tests may also help your doctor monitor your cancer.
You’ll have 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 undergo urine tests or other bodily fluid tests to check for certain markers that indicate that your cancer might be improving.
Side effects
Keytruda stimulates your immune system, causing it to attack cancer cells. The development of side effects such as inflammation can potentially suggest that Keytruda is changing your immune system activity. However, some people may not have noticeable side effects, even if the drug is effective for them.
The symptoms of inflammation depend on where it occurs. For example, lung inflammation may lead to shortness of breath, cough, or chest pain.
Immunotherapy drugs such as Keytruda are often slower to take effect than some other treatments, such as chemotherapy. This is because they help your immune system attack cancer cells instead of destroying them directly.
Keytruda infusions are generally given every 3 to 6 weeks, depending on the condition the drug is being used to treat. Research suggests that this medication 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 Keytruda works, you likely won’t notice it working in your body. However, 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 when surgery or chemotherapy are unsuitable treatments. Because of this, the goal of this approach 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 (Keytruda’s active ingredient) 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. However, some people may receive it longer if there’s evidence that it’s still effective and the side effects are minimal.
Although Keytruda can help prevent the spread of cancer for some people, it’s not effective for everyone. If this medication 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.
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 this medication 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.