FDA Approves Keytruda for Advanced or Metastatic Merkel Cell Carcinoma
The U.S. Food and Drug Administration (FDA) has granted approval for Keytruda® (pembrolizumab) as a treatment for advanced or metastatic Merkel cell carcinoma in both adults and children.1Merkel cell carcinoma (MCC) is a rare and difficult-to-treat skin cancer that is more likely to recur and is fatal in one-third of cases.2
Demonstrated effectiveness in clinical trials
Keytruda was evaluated by the FDA under priority review as a breakthrough therapy. This designation provides a faster review process and is given to treatments that meet an unmet need in serious conditions. The approval was based on data from a clinical trial which involved 50 patients with recurrent locally advanced or metastatic MCC who had not received prior systemic therapy for their advanced disease. (Most of the patients had previously had surgery or radiation therapy.)
Keytruda was administered as an intravenous (IV) infusion every three weeks. The overall response rate was 56%, meaning 56% of patients receiving Keytruda had significant shrinkage in their tumors. In addition, 24% of the patients had a complete response rate. The duration of the response was also significant: in 54%, Keytruda kept the MCC from worsening or spreading for 12 months or more, and in 96%, Keytruda kept the MCC from worsening for 6 months or more.1,3
How Keytruda works
Keytruda is a type of immunotherapy, medicines that stimulate the body’s immune system to recognize and fight cancer cells. Keytruda is a type of immune checkpoint inhibitor. T-cells (a type of white blood cell that is important in fighting cancer and foreign invaders in the body) have receptors on the surface of their cells that act like brakes. One of these brakes is called PD-1 (programmed death receptor-1). Some cancer cells evolve to engage these brakes, escaping the immune system’s defenses and causing the T-cells to ignore the cancer cells. Keytruda blocks the PD-1 receptor on T-cells, preventing the cancer cell from engaging that brake and allowing the T-cells to recognize the cancer cells.3
Common side effects of Keytruda
The most common side effects (experienced by at least 20% of patients receiving Keytruda in clinical trials) included fatigue, muscle or bone pain, decreased appetite, itchy skin (pruritus), diarrhea, nausea, rash, fever, cough, difficulty breathing, constipation, pain, and abdominal pain.1 These are not all the possible side effects of Keytruda. Patients should talk to their doctor about what to expect and report any side effects that are concerning or that don't go away.
Who should not take Keytruda?
Keytruda should not be used in women who are pregnant or planning to become pregnant, as it can harm an unborn baby. Women who are able to become pregnant should use birth control during treatment and for at least 4 months following the last dose of Keytruda.3
It is not known if Keytruda passes into breastmilk, and women who are breastfeeding or plan to breastfeed should not use Keytruda.3
Keytruda should not be used in people with immune system problems, those who have previously had organ transplants, or those with kidney, endocrine, or liver problems. Patients should discuss all their medical conditions with their doctor prior to starting treatment with Keytruda.3
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