Pre- and postoperative treatment combining AstraZeneca's immunotherapy "IMFINZI (ingredient name durvalumab)" with standard chemotherapy (FLOT, fluorouracil, leucovorin, oxaliplatin, docetaxel) was found to safely delay disease progression and recurrence and improve survival in Asian patients as well.
AstraZeneca on the 6th (local time) announced the Asian subgroup analysis of the global phase 3 gastric cancer trial "MATTERHORN" at the European Society for Medical Oncology Asia (ESMO Asia 2025) in Singapore.
The MATTERHORN phase 3 study evaluated whether adding IMFINZI to FLOT 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 proves reduced risk of recurrence and death in global trial
In the earlier global study, 948 patients were randomized to the IMFINZI+FLOT combination arm or the placebo+FLOT control arm. After two cycles of FLOT before surgery, IMFINZI or placebo was administered for up to 12 cycles after surgery.
In the interim analysis, the IMFINZI combination arm showed a 29% lower risk of disease progression, recurrence, or death. At 1 year, 78.2% of the IMFINZI arm were event-free, compared with 74.0% in the placebo control. At 24 months, the rates were 67.4% and 58.5%, respectively.
For overall survival (OS), the risk of death was 22% lower in the IMFINZI combination arm. The 3-year survival rate was 68.6%, higher than 61.9% in the FLOT-only arm. Looking at long-term survival trends, the 18-month OS was 81.1% in the IMFINZI arm and 77.1% in the placebo control; at 24 months, 75.5% versus 70.4%; and at 36 months, 68.6% versus 61.9%, with the gap widening over time.
◇ Asian gastric cancer patients show the same pattern… analysis of 180 patients in Japan, Korea, and Taiwan
The Asian subgroup analysis included 180 patients from Japan, Korea, and Taiwan.
The rate of complete tumor removal after surgery (pCR) was 18.9% in the IMFINZI combination arm, about three to four times higher than 5.6% in the placebo control. The 24-month event-free survival (EFS) was 72.1% in the IMFINZI arm and 64.2% in the placebo control, higher than in the overall global cohort (67.4%, 58.5%). The risk of events or death was 26% lower in the IMFINZI arm.
In both the IMFINZI arm and the placebo control, the incidence of grade 3–4 or higher severe reactions was similar at 87.8% and 87.5%, with neutropenia being the most common adverse event, occurring in about 69% of Asian patients. Most adverse events were within the expected range for the FLOT regimen, and treatment discontinuations or serious safety issues were rare. In the overall global cohort, the rate was around 71–72%, somewhat higher than in the Asian cohort.
◇ Korea, high early detection rate but persistent risk of recurrence… attention on IMFINZI combination
According to the World Health Organization (WHO), gastric cancer is the fifth most commonly 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 minimal, many cases are already advanced at diagnosis.
In Korea, widespread national screening leads to earlier detection and lower mortality. As of 2022, gastric cancer ranks fifth in new diagnoses, and the 5-year relative survival rate is 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 crucial.
Yelena Y. Janjigian, an oncologist at Memorial Sloan Kettering Cancer Center (MSKCC) who led the study, said, "The Asian analysis shows that in Asian patients as well, the IMFINZI combination consistently lowers the risk of recurrence and improves survival, in line with the global results."