Keytruda (Pembrolizumab)

Reviewed by: HU Medical Review Board | Last reviewed: April 2023

Keytruda (pembrolizumab) is an immunotherapy drug that can be used to treat some forms of advanced or metastatic bladder cancer. It may also be used for the treatment of patients with high-risk bladder cancer that has not grown into the bladder muscle and is not responding to Bacillus Calmette-Guerin (BCG) therapy, and who are not having all, or part of, their bladder surgically removed.1,2

Additionally, pembrolizumab may be used to treat certain forms of solid tumor cancers, which includes bladder cancer, that have specific molecular changes or biomarkers identified in the cancer and meet additional criteria. Patients receive treatment with pembrolizumab through an intravenous (IV) infusion.1-3

How does immunotherapy work?

Pembrolizumab is a type of immunotherapy drug called a PD-1 inhibitor, that has been approved to treat various forms of bladder cancer and other types of cancers. The body’s immune system consists of a group of organs and cells that work to protect the body from diseases and infections. In a patient with cancer, immunotherapy drugs work by affecting the way the immune system functions to help it fight cancer cells more effectively.1,2

How does pembrolizumab work?

Pembrolizumab works by blocking the function of a specific protein called PD-1. PD-1 is a checkpoint protein present on T cells (immune system cells) that can attach to the PD-L1 protein on certain cancer cells and help disguise them from the immune system. Because the immune system cannot detect and attack them, cancer cells can grow more easily when PD-1 is allowed to bind to PD-L1.1,2

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Who can receive pembrolizumab?

Patients with certain forms of advanced or metastatic bladder cancer can be treated with pembrolizumab. Advanced or metastatic bladder cancer means that the cancer cells have spread beyond the bladder and/or to other parts of the body. Pembrolizumab is generally prescribed for patients who have already tried treatment with a chemotherapy that contains platinum, but the chemotherapy was not effective against the cancer or it was initially effective but has stopped working.1,4

Pembrolizumab may also be used for patients with advanced or metastatic bladder cancer who are unable to receive certain platinum-containing chemotherapy. If you have advanced or metastatic bladder cancer, your healthcare providers can discuss whether treatment with pembrolizumab may be suitable.1,4

Pembrolizumab may also be used for patients with high-risk bladder cancer that has not grown into the bladder muscle and is not responding to Bacillus Calmette-Guerin (BCG) therapy. Additionally, these patients would have been unable to have bladder removal surgery (cystectomy) or would have decided not to have this surgery.3

Pembrolizumab may also be used for the treatment of solid tumor cancers with certain biomarkers, including tumors that are considered tumor mutational burden-high (TMB-H), microsatellite instability-high (MSI-H) or mismatch repair deficient (dMMR), which may include some bladder cancers. In these instances, the bladder cancer should have gotten worse after other types of treatment and there are no other available treatment options.2

Reporting other health conditions

Before prescribing pembrolizumab, healthcare providers need to know if a patient has certain other health conditions that may be made worse by taking pembrolizumab. These include:1,2

  • Immune system problems, such as Crohn’s disease or ulcerative colitis
  • Having had an organ transplant
  • Lung or breathing problems
  • Liver or kidney problems
  • Endocrine disorders such as diabetes or thyroid disorders

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 people who are pregnant.1,2

While receiving pembrolizumab, those 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). They also should not breastfeed during pembrolizumab treatment and for a period of time following the final dose (patients should discuss breastfeeding considerations with their doctor).1,2

What are the possible side effects of pembrolizumab?

The side effects that are most common in patients treated with pembrolizumab include:1,2

More serious side effects

Treatment with a PD-1 inhibitor such as pembrolizumab can help a patient’s immune system to fight cancer cells, but it can also cause the immune system to attack healthy cells. This can cause very serious side effects in some patients. Before starting treatment with pembrolizumab, healthcare providers will speak with patients about the relative benefits and risks of treatment.1,2

If a patient chooses to begin treatment with pembrolizumab, healthcare providers will explain the signs and symptoms of serious side effects so that the patient can recognize them quickly and seek treatment. Such serious side effects can include:1,2

  • Lung problems
  • Intestinal problems
  • Liver problems
  • Hormone gland problems
  • Kidney problems
  • Problems in other organs
  • Severe infusion reactions
  • Skin reactions

Patients who experience any symptoms of severe side effects should contact their healthcare providers right away to seek immediate treatment.

These are not all the possible side effects of pembrolizumab. Talk to your doctor about what to expect when taking pembrolizumab. You also should call your doctor if you have any changes that concern you when taking pembrolizumab.

Before beginning treatment for bladder cancer, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you are taking. This includes over-the-counter drugs.