FDA approves targeted therapy for gastric cancer and its companion diagnostic

Following a previous rejection in January, Astellas Pharma has received FDA approval for Vyloy (zolbetuximab-clzb) in combination with chemotherapy as a first-line treatment for locally advanced unresectable or metastatic gastric or gastroesophageal junction (GEJ) adenocarcinoma. The antibody drug is intended for tumors that are positive for claudin (CLDN) 18.2 and negative for human epidermal growth factor receptor 2 (HER2).

Vyloy is the first FDA-approved treatment to target CLDN18.2, a protein that has received a lot of interest in oncology research in recent years due to its link to several types of cancer, including gastric and pancreatic cancer.

The FDA decision was supported by positive results from two phase 3 clinical trials, Glow and Spotlight, which evaluated Vyloy in combination with two different chemotherapy regimens. The therapy is now approved in Japan, the UK, South Korea and the US.

“The approval of Vyloy in the US further delivers on our relentless pursuit of scientific progress for devastating diseases like gastric and GEJ cancers, which are often only discovered at the advanced stage. This achievement is the result of years of dedicated research and development focused on targeting a novel biomarker,” said Moitreyee Chatterjee-Kishore, Senior Vice President and Head of Immuno-Oncology Development at Astellas Pharma.

Simultaneously, the FDA has approved a companion diagnostic test to identify patients who may be eligible for treatment with Vyloy. Developed by Roche, this immunohistochemical assay is designed to measure the levels of the two variants of CLDN18 (18.1 and 18.2) in gastric and GEJ adenocarcinoma cells. Patients with 75% or more tumor cells testing positive for CLDN18.2 are deemed eligible for Vyloy.

Across the Glow and Spotlight trials, approximately 38% of patients were considered eligible for Vyloy using the companion diagnostic. Those who received a combination of Vyloy and chemotherapy experienced a 25-31% reduction in disease progression or death.

“Patients who are diagnosed with gastric or gastroesophageal junction cancer are often diagnosed in an advanced stage as early symptoms can be similar across several conditions,” said Jill German, head of pathology lab at Roche Diagnostics.

“Our companion diagnostic for CLDN18 can help identify patients eligible for targeted treatment and provide them with additional therapeutic options. With the launch of this test, Roche continues to advance personalized healthcare by expanding our innovative companion diagnostic portfolio.”