On June 1, 2025 AstraZeneca reported positive results from the MATTERHORN Phase III trial showed perioperative treatment with Imfinzi (durvalumab) in combination with standard-of-care FLOT (fluorouracil, leucovorin, oxaliplatin, and docetaxel) chemotherapy demonstrated a statistically significant and clinically meaningful improvement in the primary endpoint of event-free survival (EFS) versus chemotherapy alone (Press release, AstraZeneca, JUN 1, 2025, View Source [SID1234653555]). Patients were treated with neoadjuvant Imfinzi in combination with chemotherapy before surgery, followed by adjuvant Imfinzi in combination with chemotherapy, then Imfinzi monotherapy. The trial evaluated this regimen versus perioperative chemotherapy alone for patients with resectable, early-stage and locally advanced (Stages II, III, IVA) gastric and gastroesophageal junction (GEJ) cancers.
Schedule your 30 min Free 1stOncology Demo!
Discover why more than 1,500 members use 1stOncology™ to excel in:
Early/Late Stage Pipeline Development - Target Scouting - Clinical Biomarkers - Indication Selection & Expansion - BD&L Contacts - Conference Reports - Combinatorial Drug Settings - Companion Diagnostics - Drug Repositioning - First-in-class Analysis - Competitive Analysis - Deals & Licensing
Schedule Your 30 min Free Demo!
These results will be presented today during the Plenary Session at the 2025 American Society of Clinical Oncology (ASCO) (Free ASCO Whitepaper) Annual Meeting in Chicago, IL (abstract #LBA5) and simultaneously published in The New England Journal of Medicine.
In a planned interim analysis, patients treated with the Imfinzi-based perioperative regimen showed a 29% reduction in the risk of disease progression, recurrence or death versus chemotherapy alone (based on an EFS hazard ratio [HR] of 0.71; 95% confidence interval [CI] 0.58-0.86; p<0.001). Estimated median EFS was not yet reached for the Imfinzi arm versus 32.8 months for the comparator arm. An estimated 78.2% of patients treated with the Imfinzi-based perioperative regimen were event-free at one year compared to 74.0% in the comparator arm; the estimated 24-month EFS rate was 67.4% versus 58.5%, respectively, signaling a greater magnitude of benefit over time for the Imfinzi-based regimen.
For the secondary endpoint of overall survival (OS), a strong trend was observed in favour of the Imfinzi-based perioperative regimen (HR=0.78; 95% CI 0.62-0.97; p=0.025). The trial will continue to follow OS, which will be formally assessed at the final analysis.
Yelena Y. Janjigian, MD, Chief Attending Physician of the Gastrointestinal Medical Oncology Service, Memorial Sloan Kettering Cancer Center, New York, and principal investigator for the trial, said: "Despite receiving curative-intent surgery and chemotherapy, patients with gastric and gastroesophageal cancers frequently develop recurrent disease. Results from the MATTERHORN trial showed that more than two-thirds of patients treated with a durvalumab-based perioperative regimen had not experienced a recurrence or were progression-free after two years. This new treatment approach should become the new standard of care in this setting based on these results."
Cristian Massacesi, Chief Medical Officer and Oncology Chief Development Officer, AstraZeneca, said: "This immunotherapy-based perioperative regimen has the potential to change the clinical paradigm in early gastric and gastroesophageal junction cancers based on the reduction in risk of progression, recurrence or death by nearly a third and the strong trend towards improved survival. As the third positive trial of perioperative treatment with Imfinzi across multiple tumour types, the MATTERHORN trial further validates this approach and highlights our commitment to bringing novel therapies to early stages of disease where there is the greatest chance for cure."
Summary of results: MATTERHORN
Imfinzi-based regimen
(n=474)
Chemotherapy regimen
(n=474)
EFSi
Median EFS (95% CI) (in months)
NR (40.7-NR)
32.8 (27.9-NR)
HR (95% CI)
0.71
(0.58-0.86)
p-valueii
p<0.001
EFS rate at 12 months (%)
78.2
74.0
EFS rate at 24 months (%)
67.4
58.5
OS
mOS (in months)
NR
47.2
HR (95% CI)
0.78
(0.62-0.97)
p-valueiii
p=0.025
i. EFS rates are based on Kaplan Meier estimates.
ii. Threshold to declare statistical significance p-value<0.0239.
iii. Threshold to declare statistical significance p-value<0.0001.
Gastric (stomach) cancer is the fifth most common cancer worldwide and the fifth-highest leading cause of cancer mortality.1 Nearly one million new patients were diagnosed with gastric cancer in 2022, with approximately 660,000 deaths reported globally.1 In many regions, its incidence has been increasing in patients younger than 50 years old, along with other gastrointestinal (GI) malignancies.2 In 2024, there were approximately 43,000 drug-treated patients in the US, European Union (EU) and Japan with early-stage and locally advanced gastric or GEJ cancer.3 Approximately 62,000 patients in these regions are expected to be newly diagnosed in this setting by 2030.4
GEJ cancer is a type of gastric cancer that arises from and spans the area where the oesophagus connects to the stomach.5
Disease recurrence is common in patients with resectable gastric cancer despite undergoing surgery with curative intent and treatment with neoadjuvant/adjuvant chemotherapy. Approximately one in four patients with gastric cancer who undergo surgery develop recurrent disease within one year, and one in four patients do not survive beyond two years, reflecting high unmet medical need.6-7 Additionally, the five-year survival rate remains poor, with less than half of patients alive at five years.8
MATTERHORN
MATTERHORN is a randomised, double-blind, placebo-controlled, multi-centre, global Phase III trial evaluating Imfinzi as perioperative treatment for patients with resectable Stage II-IVA gastric and GEJ cancers. Perioperative therapy includes treatment before and after surgery, also known as neoadjuvant/adjuvant therapy. In the trial, 948 patients were randomised to receive a 1500mg fixed dose of Imfinzi plus FLOT chemotherapy or placebo plus FLOT chemotherapy every four weeks for two cycles prior to surgery. This was followed by Imfinzi or placebo every four weeks for up to 12 cycles after surgery (including two cycles of Imfinzi or placebo plus FLOT chemotherapy and 10 additional cycles of Imfinzi or placebo monotherapy).
In the MATTERHORN trial, the primary endpoint is EFS, defined as time from randomization until the date of one of the following events (whichever occurred first): RECIST (version 1.1, per blinded independent central review assessment) progression that precludes surgery or requires non-protocol therapy during the neoadjuvant period; RECIST progression/recurrence during the adjuvant period; non-RECIST progression that precludes surgery or requires non-protocol therapy during the neoadjuvant period or discovered during surgery; progression/recurrence confirmed by biopsy post-surgery; or death due to any cause. Key secondary endpoints include pCR rate, defined as the proportion of patients who have no detectable cancer cells in resected tumour tissue following neoadjuvant therapy, and OS. The trial enrolled participants in 176 centres in 20 countries, including in the US, Canada, Europe, South America and Asia.
Imfinzi
Imfinzi is a human monoclonal antibody that binds to the PD-L1 protein and blocks the interaction of PD-L1 with the PD-1 and CD80 proteins, countering the tumour’s immune-evading tactics and releasing the inhibition of immune responses.
Imfinzi is also approved in combination with chemotherapy (gemcitabine plus cisplatin) in locally advanced or metastatic biliary tract cancer and in combination with Imjudo (tremelimumab) in unresectable hepatocellular carcinoma (HCC). Imfinzi is also approved as a monotherapy in unresectable HCC in Japan and the EU.
In addition to its indications in GI cancers, Imfinzi is the global standard of care based on OS in the curative-intent setting of unresectable, Stage III non-small cell lung cancer (NSCLC) in patients whose disease has not progressed after chemoradiotherapy (CRT). Additionally, Imfinzi is approved as a perioperative treatment in combination with neoadjuvant chemotherapy in resectable NSCLC, and in combination with a short course of Imjudo and chemotherapy for the treatment of metastatic NSCLC. Imfinzi is also approved for limited-stage small cell lung cancer (SCLC) in patients whose disease has not progressed following concurrent platinum-based CRT; and in combination with chemotherapy for the treatment of extensive-stage SCLC.
Imfinzi is approved in the US and other countries as a perioperative treatment in combination with neoadjuvant chemotherapy for muscle-invasive bladder cancer based on the NIAGARA Phase III trial. Additionally, Imfinzi plus standard-of-care Bacillus Calmette-Guérin induction and maintenance therapy demonstrated a statistically significant and clinically meaningful improvement in disease-free survival for patients with high-risk non-muscle-invasive bladder cancer in the POTOMAC Phase III trial.
Imfinzi in combination with chemotherapy followed by Imfinzi monotherapy is approved as a 1st-line treatment for primary advanced or recurrent endometrial cancer (mismatch repair deficient disease only in US and EU). Imfinzi in combination with chemotherapy followed by Lynparza (olaparib) and Imfinzi is approved for patients with mismatch repair proficient advanced or recurrent endometrial cancer in EU and Japan.
Since the first approval in May 2017, more than 374,000 patients have been treated with Imfinzi. As part of a broad development programme, Imfinzi is being tested as a single treatment and in combinations with other anti-cancer treatments for patients with NSCLC, bladder cancer, breast cancer, ovarian cancer and several gastrointestinal cancers.