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Keytruda (pembrolizumab)

Keytruda® (pembrolizumab) is a type of immunotherapy. It is used to treat melanoma that:1

  • Cannot be removed with surgery (unresectable) or
  • Has spread to distant parts of the body (metastasized)
  • As adjuvant (additional) treatment after melanoma has been surgically removed in people with disease in the lymph nodes

Pembrolizumab does not come in generic form. Pembrolizumab is similar to Opdivo® (nivolumab), another drug approved to treat unresectable or metastatic melanoma. Nivolumab is also approved for adjuvant treatment after complete resection in melanoma patients with disease in the lymph nodes or metastatic disease. Pembrolizumab is also used to treat recurrent (has come back after treatment) locally advanced or metastatic Merkel cell carcinoma, as well as metastatic and recurrent cutaneous squamous cell carcinoma that cannot be cured by treatment with radiation or surgery.

Keytruda is approved to treat other cancers as well, including: non-small cell lung cancer, head and neck cancer, and classical Hodgkin lymphoma, along with others. Keytruda is also approved for the treatment of cancers with certain biomarkers, including certain solid tumor cancers that are considered tumor mutational burden-high (TMB H), microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR).1

How does Keytruda® work?

Pembrolizumab prevents melanoma cells from hiding from your immune system’s T-cells. Pembrolizumab is described in many ways, including:

  • immune checkpoint inhibitor
  • anti-PD-1 therapy
  • PD-1 inhibitor

T-cells (T-lymphocytes) are a type of white blood cell.2 T-cells fight cancer and infection. They travel through the body, checking whether the cells they find are normal (healthy) or foreign (unhealthy). A receptor on the outside surface, called PD-1, does the checking. PD-1 stands for “programmed death receptor-1.”

Cancer cells try to hide from T-cells. They have proteins called PD-L1 or PD-L2 (programmed death ligand-1 or 2) on their outside surface. When PD-L1 or PD-L2 binds (connects) to PD-1, it basically acts like an “off switch” for the T-cell. This makes the T-cell ignore the cancer cell.

Pembrolizumab binds to the PD-1 receptor.1 This blocks the receptor from interacting with PD-L1 or PD-L2. The T-cell is able to identify and attack the cancer cell.

Receiving Keytruda®

Before receiving pembrolizumab, read the Medication Guide that comes in the package. Talk to your doctor about how often and how many treatments you will need.

Pembrolizumab is given through an intravenous (IV) line. Your doctor will arrange for you to receive pembrolizumab.

What are the side effects of Keytruda®?

The most common side effects of Pembrolizumab include:1

  • Feeling tired
  • Itching
  • Diarrhea or constipation
  • Decreased appetite
  • Rash
  • Fever
  • Cough or shortness of breath
  • Muscle, bone, or joint pain
  • Nausea

Pembrolizumab can cause your immune system to attack normal (healthy) organs and tissue. Less common but serious possible side effects include:

  • Lung inflammation (pneumonitis)
  • Intestinal inflammation (colitis)
  • Liver inflammation (hepatitis)
  • Problems with hormone glands (thyroid, pituitary, adrenal, pancreas)
  • Kidney inflammation and kidney failure
  • Other problems (rash, changes in eye sight, muscle pain or weakness, joint pain, low red blood cell count, hearing problems)

Pembrolizumab is infused (put) into your vein through an IV line. Severe, life-threatening infusion reactions can occur. Symptoms include chills, shaking, shortness of breath, wheezing, itching, rash, flushing, dizziness, fever, and feeling like you may pass out.1

This is not an exhaustive list of all potential side effects of pembrolizumab. Talk to your healthcare provider or pharmacist for further information.

Who should not take Keytruda®?

If you are pregnant, plan to become pregnant, or are breastfeeding or plan to breastfeed, talk with your doctor. Pembrolizumab can cause harm to a developing fetus and should not be given to women who are pregnant. While receiving Pembrolizumab, females who can become pregnant should use contraceptives during treatment and for a period of time after completing treatment (patients should discuss appropriate birth control methods, and how long they need to use them, with their doctor). Females should not breastfeed during Pembrolizumab treatment and for a period of time following the final dose (patients should discuss breastfeeding considerations with their doctor).

Tell your doctor about any medical conditions you have, especially:

  • Immune system problems (Crohn’s disease, ulcerative colitis, lupus).
  • Previous organ transplant.
  • Lung or breathing problems.
  • Liver problems.

What precautions are needed when taking Keytruda®

You will need regular blood tests to check for side effects of Pembrolizumab. Your doctor may prescribe corticosteroids or hormone replacement medicines to treat certain side effects.1

Before starting treatment with pembrolizumab, patients should tell their doctor about all medications (prescription and over-the-counter), herbal supplements, and vitamins they are taking. Patients should talk to their doctor if they have any questions, or if they have questions regarding their pembrolizumab regimen.

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Written by: Sarah O'Brien | Last reviewed: February 2021.