Keytruda for Mesothelioma

What Is Keytruda (Pembrolizumab)?

Keytruda (pembrolizumab) is a modified protein called a humanized antibody used in mesothelioma immunotherapy. It closely matches the natural proteins already found in your body, so your immune system can accept it more easily. 

Key Facts About Keytruda for Mesothelioma

1. Keytruda is a monoclonal antibody, a lab-made protein that targets specific cancer cells to treat mesothelioma.
2. Doctors give it through an IV, so the medicine goes directly into your bloodstream. 
3. Keytruda treatments last about 30 minutes and occur every 3 weeks.
4. Combining it with chemo drugs helps people with mesothelioma who can’t undergo surgery. 

Keytruda attaches to a specific protein called PD-1 on your immune or T cells, helping them find and attack cancer. That’s why it’s called a PD-1 inhibitor or immune checkpoint inhibitor. Checkpoint inhibitors are both immunotherapies and targeted therapies. Targeted therapy blocks signals that help mesothelioma cells grow, while immunotherapy trains your immune system to recognize and attack the cancer.

Clinical trials show Keytruda is most effective when tumors don’t respond to treatment or have returned. A phase 3 trial showed improved survival time. Ongoing global trials continue exploring Keytruda for mesothelioma. Researchers often combine it with surgery or chemo.

How Does Keytruda Work to Treat Mesothelioma?

Keytruda helps your immune system find and fight mesothelioma. Some cancer cells use a protein called PD-L1 to hide from your immune system’s attacks. Keytruda prevents that from happening. Unlike chemo, which kills cancer cells directly but can also harm healthy cells, Keytruda supports your body’s natural defenses.

Dr. Catherine Perrault, a board-certified family physician and Medical Officer at The Mesothelioma Center, explains, “To understand how Keytruda works as immunotherapy, we need to understand mesothelioma cells overwhelm your immune system. Your immune system, at its baseline, is there to protect you from diseases. Mesothelioma cells trick the immune system, essentially turning it off. Keytruda stops cancer’s ability to trick your immune system.”

The FDA in September 2024 approved Keytruda combined with chemo as a first-line treatment for pleural mesothelioma. Combining these mesothelioma treatments increases their effectiveness.

Who Is Eligible for Keytruda Treatment?

Keytruda is most often used for mesothelioma that has spread, come back or can’t be removed with surgery. Some people get it alone, and others receive it along with chemo. Doctors look at many factors when deciding if Keytruda is a good option for you, including your overall health, the type of mesothelioma you have and how you’ve responded to other mesothelioma treatments.

Key Factors Doctors Consider

• General health: You should feel well enough to do most daily activities and attend regular appointments.
• PD-L1 levels: Mesothelioma tumors with more of this protein, which helps cancer hide from the immune system, may respond better to Keytruda.
• Surgical status: Keytruda is typically used when surgery isn’t an option.
• Tumor traits: A high number of changes or mutations in the mesothelioma tumor’s DNA may make Keyruda more effective.
• Visible tumors: Cancer must show up clearly on scans to measure how treatment is working.

Your mesothelioma specialist will review your test results and discuss the potential benefits and risks with you. If you’re unsure about your options, it’s always OK to ask questions or get a second opinion. The goal is to find the treatment plan that fits your needs and gives you the best chance of feeling better.

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Benefits & Side Effects of Keytruda for Mesothelioma Patients

Keytruda helps some people with mesothelioma live longer and feel better. Studies show Keytruda has been shown to shrink tumors, reduce symptoms and even help when other treatments stop working for some people. 

While it’s FDA-approved specifically for pleural mesothelioma, doctors have seen benefits for some of their peritoneal patients as well. A 2025 case report in Oncology Letters, a peer-reviewed journal, documented a late-stage peritoneal patient who lived longer than 2 years with Keytruda. 

Benefits of Keytruda for Mesothelioma

• In some studies, Keytruda helped about 20% to 25% of people see their tumors shrink.
• Keytruda can help reduce symptoms like chest pain and trouble breathing.
• It may offer a longer-lasting response than chemo for some people.
• Patients often report fewer harsh side effects than with chemo.
• In a phase 3 trial, the Keytruda plus chemo group’s response rate was 63% and the 3-year survival rate was 25%. For the chemo-only group, response rate was 40% and 3-year survival was 17%.

Many people say they like that Keytruda causes fewer side effects than chemo. It may cause tiredness or rash, but it doesn’t usually cause hair loss or strong nausea. Some people also get relief from pain or pressure in their chest or belly. Regular checkups help manage side effects early.

Pleural mesothelioma survivor Barbara Lapalla shares with us the benefits she’s felt taking Keytruda. She tells us, “I feel fantastic, better now than I have in quite a while. There’s nothing I can’t do. I’m not restricted in any way. I like staying active, keeping busy.”

Side Effects of Keytruda

People with mesothelioma report Keytruda side effects such as diarrhea, anemia and fatigue. Side effects are usually less severe than those from chemo. Report any side effects you experience to your doctor.

Common Side Effects of Pembrolizumab

• Anemia (low red blood cell count)
• Constipation
• Cough
• Diarrhea
• Dry mouth
• Fatigue
• Itching
• Loss of appetite
• Nausea
• Pain in muscles, bones or joints
• Rashes
• Shortness of breath

A total of 69% of participants in a clinical trial known as Phase 2 KEYNOTE-158 experienced side effects. But none had to stop treatment because of those side effects. The most commonly reported side effects were dry mouth, fatigue, nausea and loss of appetite. Serious side effects occurred in 12% of patients. 

Keytruda rarely causes severe immune reactions in mesothelioma patients. Rare but serious side effects can impact the lungs, liver and kidneys, involving inflammation or failure. Hormone gland issues may also develop, including hair loss, muscle aches, rapid heartbeat, headaches and weight loss. 

Keytruda Treatment Process: What to Expect

You can expect to receive the drug through an IV every few weeks. During this time, your care team will watch how your body responds. 

Steps to Starting Keytruda for Mesothelioma

1. Talk with your mesothelioma doctor about using Keytruda and take any tests needed.
2. Start getting Keytruda through an IV at a clinic or hospital.
3. Return every few weeks for more treatments, scans and checkups.
4. Tell your care team how you feel and report any changes or side effects.
5. Keep following your doctor’s advice and ask questions when needed.

Survivor Barbara Lapalla started Keytruda after chemo failed to work for her. “Keytruda, it has worked like a charm for me, although I’m not exactly sure why,” Barbara tells us. “There have been absolutely no side effects. For me, it’s the magic bullet.”

Common Questions About Keytruda for Mesothelioma

How long does it take for Keytruda to work?

Keytruda for mesothelioma may take a few weeks or months to show signs that it’s working. Doctors will see if your mesothelioma tumors have responded with scans and tests. Some people respond within a few treatments, while others need more time. Everyone’s body reacts differently. Your doctor will watch closely to see how it’s going.

Can Keytruda cure mesothelioma?

Keytruda cannot cure mesothelioma, but it can help some people live longer and feel better. It works by helping your immune system fight mesothelioma. Some patients see their tumors shrink or stop growing. Your care team will do everything they can to find the best treatment plan for you.

Can I receive Keytruda with other treatments?

Yes, doctors may give you Keytruda for mesothelioma along with other treatments like chemotherapy. This may help your body fight mesothelioma more strongly. Your doctor will choose the safest and most helpful mix based on your health.