Is Keytruda Chemotherapy? Plus, 5 More Frequently Asked Questions

If you were to ask experts, “What’s the closest thing to a wonder drug in oncology?” Keytruda (pembrolizumab) would likely be one of the top answers. With nearly 40 FDA-approved uses in more than 15 different types of cancer, it’s no wonder that it seems like Keytruda can be used for almost everything.

If you’ve been diagnosed with cancer, you wonder if Keytruda is right for you. We’ll discuss six of the most commonly asked questions about Keytruda so you can determine if Keytruda might be an option for you.

1. Is Keytruda chemotherapy?

No. Keytruda isn’t chemotherapy. It’s a type of immunotherapy, called an immune checkpoint inhibitor. It allows your immune system to better find cancer cells and destroy them. 

Depending on your type and stage of cancer, you may receive Keytruda by itself or take it with other medications, such as chemotherapy or targeted therapies.

2. How is Keytruda given?

Keytruda is given as an infusion in your vein over a period of 30 minutes. 

For most adult cancers, Keytruda is given as a 200 mg dose every 3 weeks or 400 mg every 6 weeks. Between the two, most people prefer the 6-week dosing interval. This is because they can go longer between treatments. But your healthcare team may prefer that you start off by receiving the more frequent regimen to make sure you tolerate it well. 

If it’s given to children, a dose based on body weight is used. The typical dose is 2 mg per kg of body weight every 3 weeks.

3. Do you need to get a biomarker test before receiving Keytruda?

Potentially. Cancer biomarkers are proteins, genes, or other substances that share important details about your cancer. They can tell you if your cancer is likely to spread, whether a medication is working, or if a future treatment option might be helpful. 

In certain situations, biomarkers can predict if Keytruda can work against your specific tumor. These biomarkers include programmed cell death ligand 1 (PD-L1) expression, tumor mutational burden (TMB), and DNA mismatch repair deficiency (dMMR)/microsatellite instability-high (MSI-H).

Biomarker testing is usually done for people with specific types of cancer and those with more advanced cancer. But not all cancers require biomarker testing in order for Keytruda to be effective. Talk with your healthcare team to see if biomarker testing should be a part of your care plan.

PD-L1

PD-L1 is a protein that acts as an “off switch” for immune cells called T cells. PD-L1 is made by both normal cells and tumor cells. But tumor cells make a lot more of it. The result is that T cells become blind to tumor cell growth. 

Tumors that are positive for PD-L1, or have high levels of PD-L1, may respond better to Keytruda. This is because the medication attaches to PD-L1, turning the off switch back "on.” This lets immune cells see the cancer again.

TMB

TMB tells you the number of mutations that you have in your cancer cells. Once the number of mutations is high enough, your tumor is considered tumor mutational burden-high (TMB-H). 

Those who have TMB-H tumors are more likely to have a better response to Keytruda. TMB-H can be found in any non-blood cancer, but it’s more common in skin cancers and non-small cell lung cancer.

dMMR/MSI-H

Our bodies have repair processes in place to make sure that any mistakes get corrected when we make new cells. Sometimes these repair processes fail (dMMR) and lead to a collection of mistakes known as MSI-H. 

People with MSI-H cancers are more likely to have a better response to Keytruda. Keytruda can be used for any non-blood cancer that tests positive for dMMR or MSI-H, but it’s more common in colorectal, stomach, and uterine cancers.

4. Why can Keytruda treat several types of cancer?

We’re learning more about cancer every day. We now know that PD-L1 is associated with tumor growth in many different cancers — making Keytruda treatment an option for a variety of cancers.

Keytruda has also been studied in multiple clinical trials, leading to its FDA approval in several different types of cancer. A 2018 study estimated that over 40% of people with metastatic cancer (cancer that has spread to other parts of the body) were eligible for Keytruda based on FDA-approved uses alone.

What’s more, Keytruda was the first medication to receive a tumor-agnostic indication, meaning that Keytruda can be used for any cancer that has a specific gene or protein change.

5. Is Keytruda safe?

Keytruda is safe for most people. Immunotherapy tends to be better tolerated than chemotherapy, too.

However, it’s not without its own risks. The most common Keytruda side effects are fatigue, diarrhea, and skin rashes. When Keytruda starts working and allows your immune system to see cancer cells again, it can sometimes miss its target and attack healthy cells too. This can lead to inflammation-related side effects known as immune-related adverse events (irAEs), including:

• Skin inflammation (dermatitis)

• Lung inflammation (pneumonitis)

• Gut inflammation (colitis)

• Low thyroid function (hypothyroidism)

• Liver inflammation (hepatitis)

While uncommon, irAEs can also occur in other organs, such as the kidney, liver, and heart.

6. How can you manage side effects from Keytruda?

Keytruda side effects range from mild to life-threatening. But most are manageable if they’re caught early. Reach out to your healthcare team if you experience any unusual side effects or if your side effects don’t seem to be getting better.

Below are possible management strategies for fatigue and some common irAEs.

Fatigue

Fatigue can often be managed without having to stop Keytruda. Your healthcare team may want to run some tests to make sure there isn’t something else contributing to your fatigue. Otherwise, you can try some lifestyle changes, such as:

• Staying hydrated

• Practicing good sleep hygiene

• Light exercise

• Diet changes

Skin problems

Skin problems, such as rash and itching, usually start within the first few weeks of treatment with Keytruda. For mild to moderate rashes, you’ll likely be prescribed a topical corticosteroid, (steroid) such as hydrocortisone, for treatment. If itching is an issue, taking an oral antihistamine, such as diphenhydramine (Benadryl), can help.

If the rash is widespread or comes with blistering, peeling, or fever, you should reach out to your healthcare team immediately. Keytruda has rarely been associated with various life-threatening skin conditions, such as Stevens Johnson Syndrome (SJS), toxic epidermal necrolysis (TEN), and drug rash with eosinophilia and systemic symptoms (DRESS).

Diarrhea

Diarrhea and other gut-related problems typically start within the first 6 to 8 weeks of treatment. If your diarrhea is mild, you can try the following strategies:

• Take an over-the-counter antidiarrheal such as loperamide (Imodium A-D)

• Stay hydrated 

• Avoid dietary triggers such as dairy, fried foods, and lots of fiber

If your diarrhea doesn’t improve with the above strategies, it’s time to call your healthcare team. Continued or worsening diarrhea could be a sign of an infection or colitis. 

Thyroid problems

Keytruda can cause your thyroid to be more or less active. Low thyroid activity (hypothyroidism) is more common. This usually happens 4 to 6 weeks after starting Keytruda and can come with side effects such as weight gain, constipation, and sensitivity to cold. 

Your healthcare team will regularly monitor your thyroid function with blood draws while you’re receiving Keytruda. If your thyroid levels drop too low, your healthcare provider will likely start you on thyroid hormone replacement with a medication called levothyroxine (Synthroid). 

Lung problems

Keytruda can rarely cause lung inflammation, known as pneumonitis. There isn’t a lot you can do to prevent this side effect, but it’s important that you let your healthcare team know about any new shortness of breath, dry cough, or chest pain you experience. You’ll likely have to do some imaging and be treated with steroids such as prednisone if you develop pneumonitis.

If any of the above side effects are severe or don’t improve with treatment, your healthcare team will likely need to stop Keytruda for a while.

How to save on Keytruda

There are ways to save on Keytruda, which is only available as a reference (“brand name”) medication. GoodRx can help you navigate between copay savings cards and patient assistance programs to save money on your prescription.

• Save with a copay savings card. If you have commercial insurance and meet eligibility requirements, Keytruda’s price is as little as $25 per infusion if you use the manufacturer’s savings card.

• Save with patient assistance programs. If you’re uninsured or underinsured, you may be eligible for a Keytruda patient assistance program, which offers the medication free of charge.

Why trust our experts?

Written by:

Rachel Feaster, PharmD, BCOP, BCPS

Rachel Feaster has over 10 years of professional experience in ambulatory, inpatient, pharmacogenomics, and oncology care. She is board certified in oncology and pharmacotherapy.

Edited by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Vanessa Carranza, PharmD

Vanessa Carranza, PharmD, is a pharmacist who has dedicated her career to the advancement of medical education for healthcare providers, patients, and caregivers, most notably in the oncology space.

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