How Pembrolizumab (Keytruda®) Treats Mesothelioma
Keytruda® is an immunotherapy drug categorized as an immune checkpoint inhibitor, a type of monoclonal antibody. The drug works by blocking the PD-L1 protein, which is a protein that can be found on normal and cancer cells. The protein is used by cancer cells to trick a patient’s T-cells (a type of white blood cell that detects and fights disease) into thinking the cancer is a healthy, functioning cell. Without Keytruda®, or another anti-PD-1 drug, the cancer cell uses the PD-L1 protein to connect with the PD-1 protein on the T-cell. This connection prevents the T-cell from attacking and allows the cancer to grow and spread. Keytruda® blocks the interaction between PD-1 and the PD-L1 protein on mesothelioma cancer cells, making them vulnerable to attack from the body’s immune system.
Keytruda® is administered via IV (intravenous therapy) for 30-minute increments every three weeks. Typically, courses of treatment continue for up to two years or longer if effective and well-tolerated. Keytruda® is used as a second-line treatment for mesothelioma patients whose disease did not respond or recurred after first-line treatment with either surgery, radiation or chemotherapy. Using the medication as a second-line treatment has shown promising results in multiple clinical trials to date.
The KEYNOTE-028 clinical trial conducted in 13 different sites across six different countries was the first to show success using Keytruda® to treat malignant pleural mesothelioma patients who were previously treated with chemotherapy or were considered ineligible for treatment. Researchers reported that 14 of 25 participants (56%) experienced a reduction in tumor size. Additionally, the average overall survival with Keytruda® was 18 months, and patients in the trial averaged six months with no disease progression. The average overall survival rate reported in the trial is a promising result of treatment, as the typical life expectancy for pleural mesothelioma patients is six months to one year. Researchers further noted that for patients who receive a second-line treatment, prognosis is typically six to seven months.
The efficacy of the treatment option is still being tested, with various ongoing clinical trials. Other clinical trials have shown results that have confirmed the success achieved in KEYNOTE-028. One trial conducted at The University of Chicago Medicine Comprehensive Cancer Center has found patients treated with Keytruda® experienced a 21% response rate and a 76% disease control rate so far. Though overall median survival will not be concluded until the trial’s end, researchers noted a median progression-free survival of 6.2 months.
More trials are still underway and results will continue to be reported.
Eligibility for Pembrolizumab (Keytruda®)
Keytruda® has now been included as a recommended therapy option in the National Comprehensive Cancer Network (NCCN) malignant pleural mesothelioma guidelines, meaning that patients can now receive immunotherapy drugs as a standard treatment option outside of a clinical trial. There are clinical trials involving Keytruda® and other immunotherapies used in combination with other treatments that may represent a good option for some patients.
Resources for Mesothelioma Patients
03. Side Effects
Side Effects and Risks of Pembrolizumab (Keytruda®)
Side effects with Keytruda® are typically mild, though quite common. One study from 2017 reported that 64% of their participants experienced adverse effects from the treatment. However, the most common side effects were fatigue and nausea, which were reported among 24% of patients. While more than half of patients in the study experienced side effects, no participants chose to discontinue treatment due to adverse effects, indicating to researchers that Keytruda®is a tolerable treatment with low-toxicity.
Common Pembrolizumab (Keytruda®) Side Effects
- Dry mouth
- Joint pain
- Loss of appetite
While the common side effects are relatively mild among pleural mesothelioma patients treated with Keytruda®, there are certain risks associated with any course of immunotherapy treatment. While the immunotherapy drugs work to attack the cancer cells within a patient’s body, they may also erroneously attack healthy cells and negatively impact organ function.
Autoimmune Reactions to Pembrolizumab (Keytruda®)
- Dermatitis (inflammation of the skin)
- Colitis (inflammation of the colon)
- Hepatitis (inflammation of the liver)
- Hypothyroidism (underactive thyroid)
- Hypophysitis (inflammation of the pituitary gland)
- Interstitial nephritis (inflammation of the kidneys)
- Pneumonitis (inflammation of the lung walls)
- Uveitis (inflammation of the eye)
Knowing the potential of risk, both rare and common, is important for patients prior to beginning any treatment modality. They should also ask their physician about treatment side effects to consider when undergoing both standard and experimental treatment options. For some mesothelioma patients, the benefits of treatment with Keytruda® may outweigh potential risks.
With no cure, and limited effective treatment options available to mesothelioma patients, the promise of a new treatment is a source of hope for those impacted by the disease.