Key Takeaways

  • Keytruda works by inhibiting the activity of the programmed cell death protein 1 (PD-1), which typically limits the activity of your immune system. Cancer cells often produce PD-1 to prevent your natural immune system from targeting the cancer.
  • Your doctor will order imaging scans and blood tests to determine how a tumor responds to Keytruda and whether it shrinks over time.
  • Keytruda does not cure cancer. However, if a doctor determines that you are a candidate for treatment with Keytruda, this medication may help you to live longer.

Keytruda is approved by the Food and Drug Administration (FDA) to treat certain types of cancer, such as skin cancer and lung cancer, in adults. These cancers are typically in the later stages. For some cancers, the FDA has also approved the drug for use in children.

Keytruda is a brand-name intravenous (IV) infusion containing pembrolizumab. This drug is a type of immunotherapy that belongs to the group of medications called PD-1 inhibitors.

If an oncologist (cancer specialist) prescribes Keytruda, they’ll ask you to attend regular appointments so they can check for signs that this drug is working.

This article describes the tests these appointments may include and answers some frequently asked questions about treatment with Keytruda.

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Immunotherapy is a new but promising treatment for several types of cancer. However, it may not work for everyone. When an immunotherapy drug such as Keytruda does work, the amount of time for signs to appear can vary. Keytruda may work more slowly than traditional cancer treatments such as radiation and chemotherapy.

Some people may experience a delay in their body’s response to Keytruda, and a tumor may continue to grow at first. However, others may experience an initial rapid response to the medication before its effect on a tumor slows.

Keytruda typically helps treat certain cancers in the later stages. It can prolong a person’s life, but eventually their cancer will progress or side effects will become too bothersome. At this point, doctors will recommend stopping Keytruda treatment.

An oncologist will monitor your body’s response to Keytruda throughout your treatment. This will allow them to find out whether the drug is working for you. You’ll attend regular checkups during which your doctor can use certain tests to monitor your treatment.

Imaging tests

The most common scan for monitoring cancer treatment is a CT scan. It provides an up-to-date image of the tumor, allowing your doctor to see whether the tumor shrinks with treatment.

However, researchers are exploring the benefits of MRI scans for providing a detailed view of the immune response to immunotherapy treatment for cancer.

Both types of scans will show a doctor how a tumor responds to treatment and whether it shrinks over time.

Blood tests

A doctor may order laboratory testing of blood samples to check for certain biomarkers. These natural markers occur in your bodily fluids and can show a doctor whether a tumor grows or shrinks over time.

The type of tests a doctor may use will depend on the type of cancer you have. One such test is the cancer antigen 125 (CA-125) test.

However, the FDA has not approved any blood tests to assess the effectiveness of immunotherapy. Researchers are studying the effectiveness of a type of liquid biopsy (ctDNA) that detects how well a person’s body responds to immunotherapy throughout treatment.

There is no cure for cancer. However, certain cancer treatments, including Keytruda, may offer longer life expectancies.

According to clinical trials, some people may need only 24 weeks of immunotherapy treatment, such as Keytruda, to remove any signs of cancer. However, this is likely with only certain types of cancers and is rare.

The success of Keytruda treatment depends on certain factors, such as:

  • the type of cancer you have
  • the stage of the cancer
  • previous treatments
  • your overall health

How Keytruda works

Keytruda belongs to a category of cancer treatment called immunotherapy.

Your immune system naturally destroys abnormal cells in your body, which can help prevent the growth of cancer cells. Immunotherapy medications such as Keytruda boost the immune system to target and destroy more cancer cells.

Sometimes, immune cells called tumor-infiltrating lymphocytes gather around cancer cells. This is a sign doctors may look for to determine whether a person’s body may respond to immunotherapy treatment.

Keytruda works by inhibiting the activity of the programmed cell death protein 1 (PD-1). This protein typically limits the activity of your immune system. Cancer cells often produce PD-1 to prevent your natural immune system from targeting the tumor.

Treatment with Keytruda reduces the limiting activity of PD-1, helping your immune system find and destroy more cancer cells.

Here are the answers to some frequently asked questions about treatment with Keytruda.

When do the side effects of Keytruda start? Will I feel worse before I feel better?

Side effects from Keytruda can vary. You may notice side effects after your first IV infusion or in the weeks and months after you start treatment.

Also, you may experience different side effects depending on whether you receive Keytruda alone or in combination with other cancer treatments, such as chemotherapy.

Most side effects from Keytruda are temporary. Some may go away as your body adjusts to the medication. However, some may continue throughout your treatment. In clinical trials of Keytruda, some people discontinued treatment with the drug because of side effects.

For more information about the side effects of Keytruda, talk with your doctor or pharmacist.

How long does Keytruda stay in your system?

The half-life of Keytruda’s active ingredient, pembrolizumab, is around 22 days. (A drug’s half-life is the amount of time it takes for your body to get rid of half a dose.) This means Keytruda will likely stay in your system for about 3.5 months.

If you have questions about the effects of Keytruda, talk with your doctor.

Keytruda is a type of immunotherapy medication that helps your immune system find and destroy cancer cells. If a doctor determines that you are a candidate for treatment with Keytruda, this medication may help you to live longer with cancer.

Immunotherapy is still in its early stages. Researchers are still learning how best to use these immunotherapy medications, including finding the best ways to monitor their effects throughout treatment. The current monitoring methods are imaging scans, such as CT scans, and blood tests.

Disclaimer: Medical News Today 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.