News|Articles|March 27, 2026

FDA Approves PD-L1 Test to Guide Keytruda Use in Esophageal and GEJ Cancer

FDA approves a PD-L1 test to help identify patients with esophageal or gastroesophageal junction (GEJ) cancer who may benefit from Keytruda.

Agilent Technologies Inc. announced that the U.S. Food and Drug Administration (FDA) has approved a PD-L1 companion diagnostic test for patients with esophageal cancer or gastroesophageal junction cancer.

The test, called PD-L1 IHC 22C3 pharmDx, Code SK006, is designed to help doctors figure out whether a patient may be eligible for treatment with Keytruda (pembrolizumab). It does this by checking a tumor for a specific protein called PD-L1.

For patients and caregivers, this approval means there is now an FDA-approved test that can help guide decisions about whether Keytruda may be an option as part of treatment.

What the PD-L1 test looks for

After a cancer diagnosis, doctors often send a sample of the tumor to a lab for testing. The PD-L1 IHC 22C3 pharmDx test measures how much of the PD-L1 protein is present in the tumor.

If the tumor has a Combined Positive Score of 1 or higher, it meets the requirement under this approval. Patients whose tumors reach this level may be eligible to receive Keytruda.

A companion diagnostic is a test approved by the FDA to help determine whether a patient can receive a specific drug. In simple terms, it is a type of tumor testing that helps match a patient to a treatment based on the cancer’s characteristics.

According to the company, this is the only FDA-approved companion diagnostic specifically indicated to identify patients with esophageal or gastroesophageal junction cancer whose tumors express PD-L1 at the required level for possible treatment with Keytruda.

Who may qualify for treatment with Keytruda

Keytruda is indicated for patients with locally advanced or metastatic esophageal cancer or gastroesophageal junction cancer. This includes tumors located 1 to 5 centimeters above the gastroesophageal junction that cannot be removed with surgery or treated with definitive chemoradiation.

In this setting, Keytruda is used together with platinum- and fluoropyrimidine-based chemotherapy. The PD-L1 test helps doctors determine whether a patient qualifies for this treatment combination.

Esophageal cancer remains a serious disease. In 2025, approximately 16,250 deaths in the United States were caused by esophageal cancer. The 5-year relative survival rate is 21.9%.

The PD-L1 IHC 22C3 pharmDx test is also approved to help identify patients with other types of cancer who may be eligible for Keytruda, including non-small cell lung cancer, esophageal squamous cell carcinoma, cervical cancer, head and neck squamous cell carcinoma, triple-negative breast cancer, gastric or gastroesophageal junction adenocarcinoma, and epithelial ovarian, fallopian tube, or primary peritoneal carcinoma.

The test was developed by Agilent in partnership with Merck to be used alongside Keytruda. With this approval, doctors now have an FDA-approved test to help guide treatment decisions by identifying which patients’ tumors express PD-L1 at the required level.

Are there any safety issues?

The press release did not include specific details about side effects.

Keytruda is indicated in combination with platinum- and fluoropyrimidine-based chemotherapy for eligible patients whose tumors express PD-L1 at a Combined Positive Score of 1 or higher. Patients should speak with their health care team about possible side effects and whether PD-L1 testing is appropriate for their care.

Editor's note: This article is for informational purposes only and is not a substitute for professional medical advice, as your own experience will be unique. Use this article to guide discussions with your oncologist. Content was generated with AI, reviewed by a human editor, but not independently verified by a medical professional.