Perioperative treatment combining AstraZeneca's immuno-oncology drug Imfinzi (ingredient name durvalumab) with standard chemotherapy (FLOT, fluorouracil, leucovorin, oxaliplatin, docetaxel) was shown to delay disease progression and recurrence and improve survival in Asian gastric cancer patients.
AstraZeneca said this on the 6th (local time) at ESMO Asia 2025 in Singapore, announcing a subgroup analysis of Asian patients from the global phase 3 gastric cancer trial MATTERHORN.
Yelena Y. Janjigian, an oncologist at Memorial Sloan Kettering Cancer Center (MSKCC) who led the study, said, "The efficacy of Imfinzi combination therapy was consistent with the global results."
The MATTERHORN trial evaluated whether adding Imfinzi to FLOT chemotherapy improves event-free survival (EFS) and overall survival (OS) in patients with resectable stage 2–4 gastric and gastroesophageal junction (GEJ) adenocarcinoma.
Imfinzi blocks the PD-L1 signal that prevents immune cells from attacking cancer cells, helping T cells (immune cells) resume their attack. It is already approved in the United States for patients with resectable early and locally advanced gastric and gastroesophageal junction (GEJ) adenocarcinoma and is used as neoadjuvant therapy before surgery, adjuvant therapy after surgery, and then as monotherapy.
◇ Imfinzi + FLOT combination shown to reduce risk of recurrence and death in global trial
In the trial, 948 patients were randomly assigned to an Imfinzi + FLOT combination arm or a placebo + FLOT control arm. After two cycles of FLOT before surgery, Imfinzi or placebo was administered up to 12 cycles after surgery.
At the interim analysis, the median event-free survival had not been reached in the Imfinzi combination arm. The placebo control arm recorded 32.8 months. The 24-month event-free survival (EFS) rates were 67.4% and 58.5%, respectively. The risk of events or death in the Imfinzi combination arm was 29% lower than in the placebo control arm.
The 24-month overall survival (OS) rates were 75.7% and 70.4%, respectively. At this time, the risk of death in the Imfinzi combination arm was 22% lower than in the placebo control arm.
◇ Same for Asian patients as well: analysis of 180 patients in Korea, Japan and Taiwan
The Asian subgroup included 180 patients from Japan, Korea and Taiwan. Many had an Eastern Cooperative Oncology Group performance status (ECOG PS) of 0, T4 stage, gastric cancer, and lymph node positivity.
The median event-free survival was not reached in either arm. The 24-month EFS was 72.1% in the Imfinzi combination arm and 64.2% in the placebo control arm, higher than in the overall global population (67.4%, 58.5%).
The pathologic complete response rate (pCR) was 18.9% in the Imfinzi combination arm, about three to four times higher than 5.6% in the placebo control arm. The risk of events or death was also 26% lower in the Imfinzi combination arm than in the placebo control arm.
In both the Imfinzi combination arm and the placebo control arm, the incidence of grade 3–4 or higher severe reactions was similar at 87.8% and 87.5%, and the most common adverse event was neutropenia, occurring in about 69% of Asian patients. In the overall global population, it was somewhat higher at 71–72%.
◇ Korea still faces recurrence risk despite high early detection rates; Imfinzi combination draws attention
According to the World Health Organization (WHO), gastric cancer is the fifth most frequently diagnosed cancer worldwide and the fifth leading cause of death. Between 90% and 95% of gastric cancers are adenocarcinomas that begin in the gastric mucosa, and because early symptoms are rare, many cases are already advanced at diagnosis.
In Korea, nationwide screening leads to high early detection rates and lower mortality. As of 2022, gastric cancer ranked fifth in new diagnoses, and the 5-year relative survival rate was 67–69%, far higher than in the United States (37.9%). However, more than 60% face a risk of recurrence within two years after surgery, making early recurrence prevention strategies important.