Expanding Immunotherapy to Esophageal Cancer

The FDA has expanded the use of the immunotherapeutic pembrolizumab to treat certain patients with esophageal cancer.

The U.S. Food and Drug Administration (FDA) recently approved expanding the use of pembrolizumab (Keytruda), a type of immunotherapeutic called a checkpoint inhibitor, to include the treatment of certain patients with esophageal cancer.

Pembrolizumab is intended for treating patients who have recurrent, locally advanced, or metastatic squamous cell carcinoma of the esophagus that tests positive for PD-L1 protein and that has progressed despite treatment with at least one other systemic therapeutic (meaning a treatment that travels through the bloodstream, reaching and affecting cells all over the body, after being taken by mouth or infused into the bloodstream).

Esophageal cancer accounts for about 1 percent of all new cancer cases diagnosed each year in the United States. In 2019, it is expected that 17,650 people will receive an esophageal cancer diagnosis and 16,080 people will die from the disease.

Squamous cell carcinoma is one of the most common types of esophageal cancer. It can arise throughout the esophagus, which is the tube that connects the throat to the stomach.

The approval of pembrolizumab for PD-L1–positive squamous cell carcinoma of the esophagus was based on results from one phase II and one phase III clinical trial. In the phase III clinical trial, median overall survival among patients with PD-L1–positive squamous cell carcinoma of the esophagus who received pembrolizumab was 10.3 months, compared with 6.7 months among those patients who received placebo. In the phase II trial, 20 percent of patients had partial tumor shrinkage after receiving pembrolizumab. Tumor shrinkage lasted 12 months or longer for 57 percent of these patients.

Pembrolizumab works by releasing a brake called PD-1 on cancer-fighting immune cells called T cells. Because it targets the immune system and not molecules specific to a particular cancer, it has relatively broad utility in the treatment of cancer.

Pembrolizumab was first approved by the FDA in September 2014, for treating melanoma. Since then, it has been approved for treating 11 other types of cancer, including esophageal cancer, and for treating patients with any type of solid tumor that is characterized by the presence of specific biomarkers known as microsatellite instability–high or mismatch repair–deficient.