FDA Accepts Application Seeking Approval of Keytruda-Chemo Combo for Stomach Cancer Subtypes

The FDA will review Keytruda plus chemotherapy for unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma.

The Food and Drug Administration (FDA) accepted a new application to seek approval of Keytruda in combination with two types of chemotherapy for first-line treatment of patients with locally advanced unresectable or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma.

The supplemental Biologics License Application, if approved, would allow the anti-PD-1 therapy Keytruda to be used with fluoropyrimidine- and platinum-containing chemotherapy to treat patients with this subtype of gastrointestinal cancers, according to a press release from Merck, the drug’s manufacturer.

“The five-year survival rate for patients diagnosed with metastatic gastric cancer is estimated to be only 6%, and 80% of patients with locally advanced unresectable or metastatic gastric or gastroesophageal junction adenocarcinoma have HER2-negative disease,” Dr. Scot Ebbinghaus, vice president of global clinical development for Merck Research Laboratories, said in the release. “We are committed to working closely with the FDA to bring Keytruda to more patients with gastric and gastroesophageal junction cancer who are in need of additional treatment options that may help them live longer.”

The application accepted by the FDA is based on findings from the KEYNOTE-859 trial, which demonstrated that Keytruda plus chemotherapy improved overall survival (the time from treatment assignment to all-cause death) compared with chemotherapy alone, according to the release. Patients with HER2-negative disease experienced an improvement in overall survival regardless of PD-L1 expression, which can prevent a patient’s immune system from operating properly.

Researchers conducting the KEYNOTE-859 trial enrolled 1,579 patients with HER2-negative locally advanced unresectable or metastatic gastric or GEJ adenocarcinoma. Patients were randomly assigned either Keytruda with fluoropyrimidine- and platinum-containing chemotherapy (785 patients) or placebo with chemotherapy (787 patients).

Researchers measured several factors throughout the study including overall survival, progression-free survival (the time from treatment assignment to disease worsening or all-cause death, whichever occurs first), objective response rate (the percentage of patients with a complete response, or disappearance of all target lesions, or partial response, which is a 30% decrease in the diameter of the target lesion) and duration of response (the time from first response to treatment to disease progression or all-cause death). Potential side effects were also monitored throughout the trial.

According to the release, the FDA has a target action date of Dec. 16, 2023, by which the agency decides whether the therapy will be approved or whether more data are needed to support its use.

Keytruda, in combination with chemotherapy, was approved by the FDA in 2021 for the first-line treatment of patients with locally advanced unresectable or metastatic HER2-positive gastric or GEJ adenocarcinoma.

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