Imfinzi Approved for Pre & Post-Surgery Gastric Cancer Treatment | AstraZeneca

March 25, 2026 Dr. Michael Lee – Health Editor Health

AstraZeneca Korea announced today that its immunotherapy drug, Imfinzi (durvalumab), has received approval as a pre- and post-operative treatment for resectable gastric or gastroesophageal junction adenocarcinoma. The approval marks the first time an immunotherapy has been authorized for use before and after surgery for gastric cancer in South Korea.

The approved regimen involves administering Imfinzi in combination with chemotherapy (FLOT) for two cycles before surgery, followed by two cycles of the combination therapy post-surgery, and then continuing with Imfinzi as a maintenance therapy.

Gastric cancer remains a significant health challenge, with high rates of recurrence even after surgical intervention. Approximately 40-60% of gastric cancer patients experience relapse, and half of those who relapse do so within two years, with 90% relapsing within five years, according to data cited by AstraZeneca.

The approval is based on the results of the global Phase 3 MATTERHORN trial, which evaluated the efficacy and safety of Imfinzi plus FLOT, followed by Imfinzi monotherapy, compared to standard FLOT chemotherapy alone or surgery alone in patients with resectable gastric and gastroesophageal junction adenocarcinoma.

The MATTERHORN study demonstrated that Imfinzi improved event-free survival (EFS), overall survival (OS), and pathological complete response (pCR) rates. Specifically, Imfinzi reduced the risk of disease progression, recurrence, or death by 29% (HR 0.71, 95% CI. 0.58-0.86), resulting in a significant improvement in EFS (35.2% vs 46%). Although overall survival was numerically higher in the Imfinzi group at 24 months (75.7% vs 70.4%), the difference was not statistically significant. The pathological complete response rate was also significantly higher in the Imfinzi group, at 19.2% (95% CI, 15.7-23.0) compared to 7.2% (95% CI, 5.0-9.9) in the control group.

“Even in cases where surgery is possible, a considerable number of patients experience recurrence,” said Dr. Lee Geun-uk, Professor of Hematology-Oncology at Bundang Seoul University Hospital. “Particularly in stage 2-3 gastric cancer patients, a significant proportion experience relapse despite undergoing post-operative adjuvant therapy. A recent treatment strategy encompassing both pre- and post-operative approaches was urgently needed.”

Dr. Lee added, “The MATTERHORN study confirmed clinical benefits in terms of EFS and OS compared to placebo, and the pCR rate was approximately 2.7 times higher with the existing treatment. This has significant clinical implications, and we anticipate that this new treatment option will enable more gastric cancer patients to survive longer without recurrence.”

Lee Hyun-joo, Executive Vice President of AstraZeneca’s Oncology Business Unit, stated, “Through the MATTERHORN study, we have confirmed clinical benefits of immunotherapy as a pre- and post-operative treatment for resectable gastric cancer patients. Based on this research, with Imfinzi now approved for the treatment of gastric and gastroesophageal junction adenocarcinoma, we can provide a new treatment option for domestic gastric cancer patients who have previously faced significant unmet needs.”