Keytruda (pembrolizumab)
Page Medically Reviewed and Edited by Kyle J. Becker, PharmD, MBA, BCOP This page has been fact checked by a Doctor of Pharmacy who specializes in Oncology. Sources of information are listed at the bottom of the article.
We make every attempt to keep our information accurate and up-to-date.
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Keytruda (pembrolizumab) is approved to treat cancers with a specific biomarker, the first drug approved by the U.S. Food and Drug Administration (FDA) based on cancer genetics.[1][2] For people affected by asbestos exposure, Keytruda is exciting because early studies suggest it may be a useful chemotherapy drug for mesothelioma. While more research is necessary, results are promising.
Pembrolizumab and Immunotherapy
Keytruda is an immunotherapy drug designed to help the immune system identify and attack cancer cells.[2] The immune system recognizes and attacks foreign invaders in the body. Immune system cells recognize some pathogens because of receptors called antigens on their surfaces.
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Healthy cells in the body have receptors on their surfaces that signal immune cells to leave them alone. Some cancer cells express these same receptors, called PD-1 proteins. This causes immune cells to mistake cancer cells for healthy cells and leave them alone to grow and thrive.[2]
Pembrolizumab acts on these cancer cell receptors, helping the immune system recognize them as foreign and attack them. This strategy is sometimes referred to as the immune checkpoint blockade.
Indications and Side Effects
The FDA approved Keytruda for specific types of cancers, cancers in certain stages or with certain characteristics, and cancer patients with certain biomarkers. For example, it is approved for melanoma, but only melanoma that has spread and cannot be treated surgically.
For other cancers, like non-small cell lung cancer, Keytruda is approved only in cases where the patient’s cancer worsened after treatment with standard chemotherapy drugs.
The side effects associated with pembrolizumab can be serious. Contact your doctor immediately if you have an unusual cough or diarrhea.
The most common side effects include:[1]
- Fatigue
- Rash
- Diarrhea
- Constipation
- Nausea
- Decreased appetite
- Shortness of breath
- Coughing
- Itching
More serious side effects are less common but may include:[1]
- Bruising
- Anemia
- Numbness
- Dizziness
- Hot flashes
- Flu-like symptoms
- Hair loss
- Edema
- Irregular heartbeat
- Pain
- Kidney failure
- Infections
- Insomnia
- Diabetes
- Jaundice
Chest pain, shortness of breath, and a cough may indicate a serious reaction that should be addressed immediately.[1]
Keytruda for Mesothelioma
Right now, indications for Keytruda do not include most mesothelioma patients, but research is underway to determine if it could be an effective and safe treatment for this cancer.
A study published in The Lancet Oncology showed promising results. This study shows that while other chemotherapy drugs fail mesothelioma patients, immune checkpoint drugs may be a better alternative.
The clinical trial is called KEYNOTE-028 and involved thirteen research teams in six different countries. The trial included twenty-five patients with pleural mesothelioma who had already received at least one chemotherapy treatment before the trial.
Patients received a larger than normal dose of pembrolizumab every two weeks. As a result, 20% of the patients saw reductions in tumor size, and an additional 52% had stable disease. Patients who responded had an average of twelve months of response.[3]
In 2020, the FDA approved Keytruda for certain mesothelioma patients. The approval is contingent on genetic factors. This includes patients with solid tumors with a high tumor mutational burden. Mesothelioma is one of the most common cancers with this designation.[4]
A large clinical trial using Keytruda in mesothelioma patients published results in 2020. Researchers described the duration of response of the treatment as impressive. Patients in the trial received Keytruda as a second-line treatment after others elicited no response or stalled.[5]
Keytruda for Asbestos Lung Cancer
Pembrolizumab is promising for mesothelioma patients; however, the drug is already approved for non-small cell lung cancer (NSCLC), another cancer that can be triggered by asbestos exposure. Approval for treating this kind of cancer came after clinical trial results showed it to be safe and effective. More recent studies suggest it may be more effective than standard chemotherapy drugs like cisplatin and carboplatin.
KEYNOTE-024 was a clinical trial of pembrolizumab in non-small cell lung cancer patients whose tumors express PD-L1 at 50% or higher. Data showed pembrolizumab has several advantages over traditional chemotherapy.
Patients given this drug experienced better overall survival rates, fewer less severe side effects, and improved quality of life. While some side effects were worse with pembrolizumab, overall adverse effects were lower and less severe. The benefits of pembrolizumab were seen in its use as a first-line treatment.
This trial means patients with lung cancer may be prescribed pembrolizumab instead of cisplatin or carboplatin, avoiding chemotherapy side effects and possibly achieving better results.[6]
The promise of immunotherapy drugs for cancer treatment is overwhelmingly positive. Keytruda is paving the way to a new strategy for better treatment of mesothelioma. There are now more than ninety ongoing clinical trials using Keytruda to treat various types of cancers.
Approval for Keytruda Expands, Hope for Mesothelioma Patients
In June of 2019, the FDA announced a new indication for Keytruda. It is now approved for the first-line treatment of metastatic, unresectable, or recurrent head and neck squamous cell carcinoma (HNSCC).
The FDA has approved the immunotherapy drug as a combination treatment with chemotherapy and as a stand-alone treatment for HNSCC patients with PD-L1 expression on the tumor cells.
This is important news, not just for the HNSCC patients who may benefit from Keytruda but also for mesothelioma patients. HNSCC is a rare cancer that is difficult to treat, just like mesothelioma. The approval for pembrolizumab is an important step in giving mesothelioma patients more hope of improved survival.
It is also a step in the direction of getting drugs like this approved for other rare cancers. The approval came after the clinical trial KEYNOTE-048 showed the drug could significantly prolong patient survival.
Two new mesothelioma trials are expected to start soon. If you are struggling with mesothelioma, pembrolizumab is not currently approved for treatment; however, you may be able to participate in a clinical trial. Talk to your doctor about getting involved if you qualify for this revolutionary treatment for this difficult type of cancer.
Page Medically Reviewed and Edited by Kyle J. Becker, PharmD, MBA, BCOP
Kyle J. Becker, PharmD is certified by the Board of Pharmacy Specialties in Oncology Pharmacy. Dr. Becker earned his pharmacy degree from Shenandoah University and he currently serves as an oncology pharmacist at Parkview Cancer Institute.