FDA Approves Keytruda (Pembrolizumab) for Stomach Cancer

The US Food and Drug Administration (FDA) has approved Keytruda (pembrolizumab) to treat people with certain cancers of the stomach or gastroesophageal junction, the area where the stomach connects to the esophagus. The approval is for people with advanced cancers called adenocarcinomas that have come back or continued to grow after having at least two previous treatments.

The cancer cells must also test positive for the PD-L1 protein. The FDA also approved a new lab test to check these cancers for the PD-L1 protein.

Keytruda is a type of immunotherapy drug called an anti-PD-1 drug. The PD-L1 protein on the surface of some cancer cells can help them avoid being found and destroyed by the body’s immune system. Drugs that block the PD-L1 protein, or the corresponding PD-1 protein on immune cells, can help the immune system recognize the cancer cells and attack them.

The FDA based its approval on a study of 259 people with stomach cancer or gastroesophageal junction adenocarcinoma. In the study, 143 people had tumors that tested positive for PD-L1.  Among these patients, 2 people had a complete response, which means they no longer had any evidence of cancer, and 17 people had a partial response, meaning their cancer shrank. Among the responses, 58% lasted 6 months or longer and 26% lasted 12 months or longer.

Keytruda is given as an infusion into a vein every 3 weeks. The most common side effects are fatigue, pain, decreased appetite, itching, rash, diarrhea, nausea, fever, cough, shortness of breath, and constipation. Keytruda also has the potential to cause the immune system to attack other parts of the body, which can lead to severe side effects.

Keytruda was approved under the FDA’s accelerated approval program for drugs that show promise against a serious disease. The company that makes the drug must submit additional clinical information after approval, to demonstrate its benefit.

Keytruda is marketed by Merck & Co., Inc.

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