Mesothelioma and Keytruda® (Pembrolizumab)
Keytruda® (pembrolizumab) is an immunotherapy drug approved by the FDA in September 2024 for first-line treatment of pleural mesothelioma, combined with chemotherapy. In the KEYNOTE-483 trial, patients on Keytruda with chemotherapy lived a median of 17.3 months, versus 16.1 months on chemotherapy alone.
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What Is Keytruda (Pembrolizumab)?
Keytruda® (pembrolizumab) is an immunotherapy drug that may extend life expectancy for mesothelioma patients. Immunotherapy drugs work with a patient’s immune system to kill cancer cells. Keytruda is categorized as an immune checkpoint inhibitor. It blocks a protein on immune cells, which allows them to recognize and kill cancer cells.
- Generic name: Pembrolizumab is the generic name for Keytruda.
- Brand name: Keytruda is the brand name for pembrolizumab.
- Administration: Keytruda is administered intravenously.
- Drug combinations: Keytruda may be combined with Alimta® (pemetrexed) and platinum chemotherapy.
- Types of mesothelioma treated: Keytruda is used in the treatment of pleural mesothelioma, peritoneal mesothelioma, epithelioid mesothelioma, biphasic mesothelioma and sarcomatoid mesothelioma.
- Manufacturer: Keytruda is manufactured by Merck & Co. Inc.
- FDA approval: Keytruda is approved to treat unresectable advanced or metastatic pleural mesothelioma when combined with chemotherapy. It can also treat several other cancers, including non-small cell lung cancer (NSCLC) and tumor mutational burden-high (TMB-H) cancer. Some of the drug’s approvals recommend administration along with other therapies, such as chemotherapy.
In September 2024, the U.S. Food and Drug Administration (FDA) approved Keytruda with pemetrexed and platinum chemo. This combination is now a first-line treatment for inoperable pleural mesothelioma. This development is based on results from the KEYNOTE-483 clinical trial. In the study, mesothelioma patients received either chemo or chemo and Keytruda. Patients who received Keytruda with chemo had a median overall survival of 17.3 months, compared with 16.1 months for patients who received chemo alone.
Another of Keytruda’s approved uses may cover other types of mesothelioma. Doctors can prescribe Keytruda for patients whose cancers fall into a category called tumor mutational burden-high (TMB-H). TMB-H means that tumor cells have a high number of genetic mutations. Some peritoneal mesothelioma tumors fall into the TMB-H category. Doctors may prescribe Keytruda in such cases.
How Does Keytruda (Pembrolizumab) Treat Mesothelioma?
Keytruda is an immunotherapy drug called an immune checkpoint inhibitor. Keytruda works by blocking the PD-1/PD-L1 immune checkpoint. This checkpoint function is similar to a secret handshake. The PD-L1 protein on a cancer cell can “shake hands” with the PD-1 protein on a T cell, a type of immune cell. This tells the T cell to ignore the cancer cell, shielding the cancer cell from attack.
When Keytruda blocks the checkpoint, mesothelioma cancer cells cannot use it to hide. This allows T cells to recognize and kill cancer cells.
Keytruda for Pleural Mesothelioma
Keytruda may be used to treat pleural mesothelioma. In one study, median overall survival from the start of Keytruda treatment for pleural patients was 18 months.
When coupled with other treatments, Keytruda may extend survival even longer. One study tested Keytruda with another form of immunotherapy in stage 3 and 4 patients who had already received another type of treatment. Median overall survival was nearly 24 months.
Keytruda for Peritoneal Mesothelioma
Keytruda has also been tested as a treatment for peritoneal mesothelioma patients. Studies for this type of mesothelioma are more limited but indicate improved survival for some patients.
Keytruda for Asbestos-Related Lung Cancer
Mesothelioma is not the only asbestos-related cancer Keytruda can treat. This immunotherapy drug can also treat some forms of NSCLC. Doctors can use Keytruda alongside platinum and pemetrexed chemotherapy for qualified cases of NSCLC.
In one study, patients with NSCLC received chemotherapy and Keytruda. Median survival was 22 months. Compared to chemotherapy alone, Keytruda more than doubled survival.
Did You Know?
Some treatments for mesothelioma are not covered by insurance.
Treatment for mesothelioma can become a financial burden.
What to Expect During the Keytruda (Pembrolizumab) Treatment Process
Keytruda is administered via IV (intravenous therapy). IV infusions take about 30 minutes and occur every three weeks. Courses of treatment may continue for up to two years or longer if effective and well-tolerated.
In 2025, the FDA also approved Keytruda Qlex, a version of the drug given as an injection under the skin rather than through an IV. A Keytruda Qlex injection takes about 1 to 2 minutes, compared with the 30-minute IV infusion. A care team decides which form is right for each patient.
Since September 2024, Keytruda combined with chemotherapy has been a first-line treatment for inoperable pleural mesothelioma. Keytruda has also been studied as a second-line treatment for mesothelioma patients whose disease did not respond to, or recurred after, an earlier treatment such as surgery, radiation or chemotherapy. Both uses have shown promising results in clinical trials.
Survival After Keytruda (Pembrolizumab) for Mesothelioma
Several clinical studies have evaluated the effect of Keytruda on mesothelioma prognosis. Median survival for pleural mesothelioma patients receiving Keytruda ranges from 10 to 18 months.
Mesothelioma Survival in the KEYNOTE-028 Clinical Trial
The KEYNOTE-028 clinical trial involved 13 different sites across six countries. It was one of the earliest studies to report success in treating malignant pleural mesothelioma with Keytruda. Study participants had previously received chemotherapy or did not qualify for standard treatment. Researchers reported several encouraging results:
- Five of the 25 patients (20%) had a confirmed partial response and 13 (52%) had stable disease, for a disease control rate of 72%.
- Patients experienced about five months with no tumor progression.
- Median overall survival reached 18 months.
This median survival result falls among the best reported for second-line mesothelioma therapy. The success of this early trial may have motivated researchers to continue studying this drug.
A later, randomized phase III trial (PROMISE-meso) tested Keytruda alone against standard chemotherapy in patients whose mesothelioma had already progressed on chemo. More patients responded to Keytruda. But the trial found no difference in overall survival between the two groups, partly because most patients on chemotherapy switched to Keytruda once their disease progressed.
Mesothelioma Survival After Keytruda (Pembrolizumab) Combination Immunotherapy
Another mesothelioma clinical trial investigated Keytruda as part of a combination treatment. The combination extended survival to nearly two years. Researchers achieved this by combining Keytruda with another immunotherapy: CAR T cells.
CAR T-cell therapy is a new approach to cancer treatment. Doctors use a patient’s own immune cells to create cancer-fighting cells called CAR T cells. Once they have enough, doctors give the CAR T cells back to the patient. The CAR T cells can then identify and attack cancer cells.
Prior to the study, participants had already received at least one form of mesothelioma treatment. After enrolling, pleural mesothelioma patients first underwent CAR T-cell therapy. Weeks later, they received Keytruda. Researchers found Keytruda helped the CAR T cells fight cancer.
Patients receiving Keytruda with CAR T cells had a median survival of 23.9 months. Notably, more than 70% of the patients in this study had late-stage mesothelioma. Mesothelioma life expectancy in later stages ranges from 12 to 16 months. This means CAR T cells and Keytruda may have improved survival by one year for these patients.
Mesothelioma and Keytruda (Pembrolizumab) Research Is Ongoing
The efficacy of Keytruda for mesothelioma is still being tested, with various ongoing studies. Several active mesothelioma clinical trials include Keytruda as part of their treatment approach.
In some studies, Keytruda will provide one part of a multimodal mesothelioma treatment. This may prove beneficial, as multimodal treatment has come the closest to a mesothelioma cure.
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Side Effects and Risks of Keytruda (Pembrolizumab)
Side effects with Keytruda are typically mild, though common. In the KEYNOTE-028 trial, 64% of mesothelioma patients who received Keytruda reported at least one side effect. The most common side effects were nausea and fatigue, reported by 24% of patients. Other common Keytruda side effects include joint stiffness, itching, decreased appetite and dry mouth.
None of the study patients discontinued treatment due to severe side effects.
- Abdominal pain
- Constipation
- Cough
- Decreased appetite
- Diarrhea
- Difficulty breathing (dyspnea)
- Fatigue
- Fever
- Itching
- Musculoskeletal pain (body aches and pains)
- Nausea
- Rash
The common side effects are relatively mild among pleural mesothelioma patients treated with Keytruda. However, some patients with other cancers have experienced more serious reactions.
In certain cases, Keytruda patients have had immune-mediated responses or autoimmune reactions. This means Keytruda may allow the patient’s immune system to attack healthy tissues or cause other problems. Such reactions are considered uncommon and may resolve after discontinuing treatment.
- Colitis (inflammation of the colon)
- Dermatitis (inflammation of the skin)
- Hepatitis (inflammation of the liver)
- Hypophysitis (inflammation of the pituitary gland)
- Hypothyroidism (underactive thyroid)
- Nephritis (inflammation of the kidneys)
- Pneumonitis (inflammation of the lung walls)
- Uveitis (inflammation of the eye)
Any patient interested in Keytruda should discuss it with an oncologist. Mesothelioma patients can discuss side effects and advantages with their doctor. A mesothelioma expert can help patients weigh the benefits and risks of standard and emerging treatments.
Eligibility for Keytruda (Pembrolizumab)
Keytruda combined with chemotherapy has become a standard, first-line treatment for many patients with inoperable pleural mesothelioma, rather than an option tried only after other treatments fail. Keytruda has FDA approval for use in patients with inoperable pleural mesothelioma.
It is also approved on its own for TMB-H classified tumors. This means peritoneal mesothelioma patients with the following characteristics may qualify for Keytruda treatment:
- Doctors consider the patient’s case inoperable.
- The patient has no other satisfactory treatment options.
- The patient has received another treatment first, and the cancer has progressed despite treatment.
- The patient’s tumor falls into the TMB-H category. TMB-H status means the tumor has a high number of genetic mutations.
Any mesothelioma patient considering Keytruda should discuss their options with a doctor. A mesothelioma doctor can help them understand the risks and benefits of available therapies. Together, the patient and doctor can devise the best approach for the patient’s unique situation.
Common Questions About Keytruda (Pembrolizumab)
Can Keytruda cure mesothelioma?
How much does Keytruda cost?
Before insurance coverage, Keytruda doses given every three weeks cost $12,272, which is the current list price Merck publishes. However, patients will often pay significantly less than the list price after insurance coverage. For example, 39% of patients with a Medicare Advantage plan paid no out-of-pocket costs for Keytruda. Among patients with commercial insurance, 59% paid nothing out of pocket. For patients who do need to pay out-of-pocket costs, mesothelioma financial assistance may help cover these.
A patient’s out-of-pocket costs will vary based on their full coverage and treatment details. Insurance providers and healthcare professionals can help patients estimate the full cost of Keytruda treatment.
Is Keytruda a first-line treatment for mesothelioma now?
Yes, Keytruda is a first-line treatment for pleural mesothelioma that cannot be treated with surgery. Since September 2024, doctors can prescribe Keytruda with chemotherapy as an initial treatment, not only after another treatment has stopped working.
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Dr. Francis Perry Wilson is the Director of the Clinical and Translational Research Accelerator at the Yale University School of Medicine. He specializes in nephrology and clinical research.
Liza Adelberg has more than 20 years of experience in marketing and communications. At Mesothelioma.com, she creates clear, compassionate resources for patients and families affected by asbestos-related diseases.
