Keytruda for Mesothelioma

FDA Approval of Keytruda for Mesothelioma

The U.S Food and Drug Administration approved Keytruda in June 2020 for a segment of unresectable or metastatic cases of malignant pleural mesothelioma. Patients must have a high tumor mutational burden, meaning the tumor has a high volume of genetic mutations. In mesothelioma, the high TMB is due to high levels of PD-L1.

Keytruda is only approved for mesothelioma as a second-line treatment. Patients also must have tried chemotherapy first before receiving Keytruda for mesothelioma. The only way patients can get Keytruda as a first-line treatment is through a clinical trial.

Unresectable means surgery cannot be performed as it will not benefit the patient. This usually describes advanced-stage mesothelioma (stage 3 or stage 4).

The FDA approval came along with the FoundationOneCDx assay (Foundation Medicine, Inc.) as a companion diagnostic for pembrolizumab. FoundationOneCDx is to be used to help identify patients with types of solid tumors who may be eligible for treatment with Keytruda.

How Keytruda Works

Keytruda is a type of immunotherapy drug called a checkpoint inhibitor. These types of drugs boost the immune system’s ability to respond to aggressive cancers like mesothelioma. In more technical terms, Keytruda stops cancerous proteins from subduing the immune system.

PD-1 and PD-L1

The immune system has soldier cells, known as T cells, that attack and kill diseases. However, mesothelioma cells have surface proteins that subdue T cells.

Mesothelioma tumors include a protein called PD-L1, which interacts with the PD-1 protein found on T cells. When PD-L1 and PD-1 bind together, T cells no longer recognize mesothelioma tumors as a threat to the body. This means they cannot actively fight off disease, allowing cancer to spread freely.

Keytruda Blocking PD-L1

Keytruda blocks interactions between PD-L1 and PD-1 proteins, preventing the binding of the two proteins. By blocking the interaction, T cells remain active and alert, ready to fight off mesothelioma.

Keytruda helps the immune system perform to its best ability, helping it to attack and kill cancer cells and preventing them from growing and spreading throughout the body.

Mesothelioma Survival With Keytruda

The FDA looks at two factors when approving or rejecting a therapy for a disease: safety and survival. Keytruda provided patients and specialists with hopeful mesothelioma survival rates.

Keytruda’s FDA approval came shortly after the success of a study involving Keytruda for tumor mutational burden-high (TMB-H) cancers:

• 24% of participants had a partial response rate (meaning their disease shrunk slightly). 
• 5% had a complete response (meaning their disease shrunk significantly or completely).

The study also compared how Keytruda helped TMB-H patients and non-TMB-H patients:

• 26.4% of TMB-H patients had progression-free survival for one year, compared to just 14% of the non-TMB-H patients. 
• 18.9% of TMB-H patients had progression-free survival for two years, compared to just 6.5% of people with non-TMB-H cancers.

Side Effects of Keytruda

The FDA often relies on side effects to determine the safety of a drug. Chemotherapy can present side effects, such as mild fatigue, severe nausea, weakened bones or nerve damage. 

The side effects of Keytruda are not usually as intense, but they can vary depending on your medication regimen. Typical side effects of Keytruda include:

• Fatigue 
• Muscle pain 
• Rash 
• Diarrhea 
• Fever 
• Cough 
• Decreased appetite 
• Itching 
• Bone or joint pain
• Shortness of breath 
• Constipation 
• Abdominal pain
• Nausea 
• Low levels of thyroid hormone 

If you’re taking Keytruda along with other prescription drugs, your side effects may become more severe. Consult your doctor to see if you’re eligible for a different mesothelioma immunotherapy drug.

Process of Keytruda for Mesothelioma

Keytruda is given through an IV (intravenously) for 30-minute increments every few weeks. Keytruda is usually given every three weeks.

Patients can receive Keytruda as long as they want. Some patients continued receiving Keytruda every few weeks for multiple years. The length of your treatment depends on how mesothelioma responds to the immunotherapy and whether you experience severe side effects.

How to Get Keytruda for Mesothelioma

The first step is to receive a medical diagnosis. This requires a consultation from your doctor, imaging tests to look for evidence of cancer and a biopsy at a hospital or cancer center.

If your mesothelioma is in an early stage, you may be a candidate for surgery. This is the best option for treatment. If surgery isn’t possible, then you can ask about Keytruda.

Patients can go to their local medical facility or a top cancer center for regular doses of the immunotherapy, as many local cancer hospitals and oncologists offer Keytruda treatment. However, it’s recommended for patients to see a mesothelioma specialist first to make sure Keytruda is the right treatment option. Most local oncologists don’t know the best ways to treat mesothelioma.

You have the best chances of receiving immunotherapy at a top-ranked mesothelioma cancer center. These facilities are more likely to provide therapies other than chemotherapy. Some examples include:

• Brigham and Women’s Hospital in Boston
• Baylor St. Luke’s Medical Center in Houston
• Moffitt Cancer Center in Tampa