Pembrolizumab (brand name: Keytruda) is a prescription immunotherapy drug used to treat many different types of cancer in adults and children. Adult uses include:

• Advanced Melanoma (skin cancer)
• Non-Small Cell Lung Cancer
• Head and Neck Squamous Cell Cancer
• Classical Hodgkin Lymphoma (a type of blood cancer)
• Primary Mediastinal Large B-Cell Lymphoma (PMBCL)
• Urothelial (Bladder) Cancer
• Microsatellite Instability-High or Mismatch Repair Deficient Cancer (cancer that affects the proper repair of DNA inside the cell).
• Microsatellite Instability-High or Mismatch Repair Deficient Colorectal Cancer (CRC)
• Gastric (Stomach) Cancer
• Cervical Cancer
• Hepatocellular (Liver) Carcinoma
• Merkel Cell Carcinoma (rare type of skin cancer)
• Renal (Kidney) Cell Cancer
• Tumor Mutational Burden-High (TMB-H) Cancer (cancers that have many gene mutations)
• Cutaneous Squamous Cell Carcinoma (skin cancer)
• Small Cell Lung Cancer
• Esophageal Cancer
• Endometrial Cancer
• Triple Negative Breast Cancer

In April 2020 Keytruda was also approved for adults at a dosing regimen of 400 mg every 6 weeks, in addition to 200 mg every 3 weeks.

See: Keytruda (pembrolizumab) dosing (in more detail)

Keytruda is also approved to treat various types of cancers in children, such as:

• Classical Hodgkin Lymphoma
• Primary Mediastinal Large B-Cell Lymphoma
• Microsatellite Instability-High or Mismatch Repair Deficient Cancer
• Merkel Cell Carcinoma
• Tumor Mutational Burden-High (TMB-H) Cancer

Pembrolizumab (Keytruda) from Merck was first approved in September 2014, and since that time over 19 new indications have been approved. Pembrolizumab is currently being evaluated in close to 500 clinical trials evaluating various cancers, according to the NIH. Ongoing investigational studies for new uses for pembrolizumab include:

• Chronic Myelogenous Leukemia
• Mesothelioma
• Recurrent Malignant Glioma (a type of brain cancer), among many others.

Other new uses for Keytruda treatment will most likely be approved by the FDA over time.

Learn more: FDA Approval History for Keytruda

How effective is pembrolizumab in cancer treatment?

Some, but not all people, have a very positive response with checkpoint inhibitors like pembrolizumab and achieve remission. For some patients, pembrolizumab (Keytruda) can be used as a first-line treatment or combined with medicines after their diagnosis.

How well pembrolizumab works for an individual patient will be based on many factors, including:

• their specific type of cancer
• whether they express certain genetic markers on their tumors
• their overall health at the time of treatment
• previous cancer treatments
• their ability to tolerate the side effects of the medication.

In some patients, tumors have regressed and disappeared with checkpoint inhibitors. Some patients have extended their survival for years. But this does not necessarily mean they are "cured", that the cancer won't return, or that everyone will respond. Talk to your doctor about how well pembrolizumab may work for you and your specific type of cancer.

Clinical studies can give you an idea how well a treatment can work for a disease and are the gold standard for drug approvals. But one study cannot give you an overall picture of how well your treatment might work. Results can be variable and cancer treatment is very individual. There are many studies done in all of the various cancers that pembrolizumab is approved to treat. It's important to discuss your expected treatment outcomes with your doctor.

Here are examples of study results looking at the effectiveness of pembrolizumab (Keytruda) in three different cancers: advanced melanoma, non-small cell lung cancer and Hodgkin lymphoma.

Advanced Melanoma

The first cancer that pembrolizumab (Keytruda) was approved for was advanced melanoma, a type of serious skin cancer that cannot be surgically removed or has spread in the body.

• When compared to ipilimumab (Yervoy), another immunotherapy drug used to treat melanoma, researchers found more patients treated with pembrolizumab were alive at the time of follow-up compared to patients treated with ipilimumab. Results showed that 67% (185 of 277) of patients who received pembrolizumab were alive at the follow-up compared to 60% (166 of 278) of patients who received ipilimumab.
• In addition, pembrolizumab helped to shrink tumors: 33% of patients who received pembrolizumab had tumor shrinkage, compared to 12% treated with ipilimumab.
• Pembrolizumab given every 3 weeks was shown to reduce the risk of dying by 31% compared to ipilimumab.
• Half of patients who received pembrolizumab given every 3 weeks were alive without their cancer spreading, growing, or getting worse at 4.1 months, compared to 2.8 months for patients on ipilimumab.

Non-Small Cell Lung Cancer (NSCLC)

Pembrolizumab was studied in patients with advanced NSCLC (when used alone as a first treatment) and was compared to treatment with a platinum-containing chemotherapy. All patients tested positive for the biomarker PD-L1 at a level of 50% or more.

• In this study, more patients receiving pembrolizumab lived longer (71%) than those receiving chemotherapy (58%).
• Half of patients were alive without their cancer progressing at 10.3 months compared to 6 months for those receiving chemotherapy.
• More patients receiving pembrolizumab had their tumors shrink (45%) vs. chemotherapy (28%).
• Pembrolizumab reduced the risk of cancer spreading, growing, or getting worse by 50% when compared to chemotherapy.

Longer term (5-year) study results (from the KEYNOTE-024 study) are now available for pembrolizumab (Keytruda) treatment of advanced NSCLC. Data published in 2020 shows that at 5 years, the overall survival rate was twice as high for patients who received pembrolizumab (31.9%) when compared to a chemotherapy (16.3%) regimen. Pembrolizumab also reduced the risk of death by 38% versus chemotherapy (a median overall survival of 26.3 versus 13.4 months).

Classical Hodgkin Lymphoma (cHL)

Pembrolizumab was studied in patients with classical Hodgkin lymphoma (cHL) whose treatment did not work or whose cancer had returned after 3 or more types of treatment. Some patients had already received a stem cell transplant. Patients received 200 mg of Keytruda every 3 weeks.

• Sixty-nine percent of 210 patients had a response to treatment and had a complete or partial response.
• The median time of response to treatment was 11.1 months in patients who responded to pembrolizumab.

Bottom Line

• Pembrolizumab (brand name: Keytruda) from Merck was first approved in September 2014 and since that time over 19 cancer uses have been approved by the FDA. It treats cancers ranging from advanced skin cancer, to bladder cancer to lung cancer.
• Pembrolizumab is now approved to treat certain lymphomas, a type of blood cancer, in addition to solid tumors
• Talk to your doctor about how well pembrolizumab may work for you and your specific type of cancer, as everyone's cancer treatment is unique.

This is not all the information you need to know about pembrolizumab (brand name: Keytruda) for safe and effective use. Review the full pembrolizumab (Keytruda) product information here, and discuss this information with your doctor or other health care provider.