MATTERHORN trial – FLOT plus durvalumab will become the new standard of care in the preoperative setting for gastroesophageal cancer

Today, AstraZeneca announced positive results from the MATTERHORN study where the chemotherapy regimen FLOT (fluorouracil, leucovorin, oxaliplatin, and docetaxel) with the immunotherapy drug Imfinzi (durvalumab) significantly improves patient outcomes, setting a new benchmark for preoperative treatment of one of the most lethal cancers – gastric and gastroesophageal cancer.

Gastric cancer is the 5th deadliest cancer worldwide, with nearly one million new cases diagnosed each year. Despite current treatment options, recurrence remains a major challenge—one in four patients experiences cancer relapse within a year with poor rates of 5-year survival.

With the MATTERHORN trial, the combination of immunotherapy and chemotherapy nearly tripled the pathologic complete response rate compared to chemotherapy alone with a 19% vs 7% reported by the previous interim analysis.

And now, while the final results are awaiting, there seems to be a trend toward an improved OS as well with the combinational regimen.

A Shift in Standard Treatment

MATTERHORN is first global, randomised Phase III trial to demonstrate superior event-free survival with an immunotherapy combination over standard of care in this setting and was conducted in 176 centres in 20 countries. The principal investigator of the study Dr Yelena Janjigian, Chief of Gastrointestinal Oncology at Memorial Sloan Kettering Cancer Center, shared her comments on the success of study with OncoDaily:

“MATTERHORN team thrilled to share the positive top-line results from the MATTERHORN study, demonstrating that FLOT plus durvalumab will become the new standard of care in the preoperative setting for gastroesophageal cancer.

Building on the foundation set by landmark trials such as FLOT4, TOPGEAR, and ESOPEC, the MATTERHORN study not only solidifies the pivotal role of FLOT in the perioperative management of gastroesophageal cancer but also introduces a perioperative immunotherapy option in localized disease.

This marks a significant paradigm shift away from traditional perioperative chemoradiation and toward a more targeted and effective treatment approach.” – says Dr Janjigian.

A Global Effort, A Shared Success

Dr. Janjigian credited the success of the study to the patients and caregivers who participated, recognizing their vital role in advancing cancer treatment:

“We extend our deepest gratitude to the patients and caregivers whose trust and participation made this study possible. Their courage and commitment are at the heart of every breakthrough in cancer care.

Thank you to everyone involved for your exceptional teamwork, dedication, and unwavering commitment to advancing cancer care on a global scale.”

As the study moves toward final overall survival (OS) analysis, the potential for long-term benefits are yet to be announced during the major upcoming events, as reported by AstraZeneca.

Find out more about the latest advancements in oncology with OncoDaily.

See the press release by AstraZeneca below.

MATTERHORN is the first global, randomised Phase III trial to demonstrate superior event-free survival (EFS) with an immunotherapy combination over the standard of care in this setting.

Imfinzi plus chemotherapy more than doubled the pathologic complete response (pCR) rate in a previously reported analysis of this trial in 2023.

Positive high-level results from the MATTERHORN Phase III trial showed that perioperative treatment with AstraZeneca’s Imfinzi (durvalumab) in combination with standard-of-care FLOT chemotherapy (fluorouracil, leucovorin, oxaliplatin, and docetaxel) demonstrated a statistically significant and clinically meaningful improvement in EFS. 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.

For the secondary endpoint of overall survival (OS), a strong trend was observed in favor of the Imfinzi-based regimen at this interim analysis. The trial will continue to follow OS, which will be formally assessed at the final analysis.

Gastric cancer is the fifth leading cause of cancer death globally, with nearly one million people diagnosed each year. In 2024, there were roughly 43,000 drug-treated patients in the US, European Union (EU), and Japan with early-stage and locally advanced gastric or GEJ cancer. Approximately 62,000 patients in these regions are expected to be newly diagnosed in this setting by 2030.

Yelena Y. Janjigian, MD, Chief Attending Physician of the Gastrointestinal Medical Oncology Service, Memorial Sloan Kettering Cancer Center, New York, and principal investigator in the trial, said:

“Despite receiving curative-intent chemotherapy and surgery, patients with gastric cancer commonly face disease recurrence and have a poor prognosis. These exciting data from MATTERHORN show that a durvalumab-based perioperative regimen resulted in a clinically meaningful improvement in patient outcomes, including decreasing the risk of the cancer coming back.”

Cristian Massacesi, Chief Medical Officer and Oncology Chief Development Officer, AstraZeneca, said:V

“MATTERHORN is the first Phase III trial of an immunotherapy to show a statistically significant improvement in event-free survival in patients with resectable gastric and gastroesophageal junction cancers. This perioperative approach with Imfinzi underscores our commitment to moving into earlier stages of cancer where novel therapies can have the biggest impact on patients’ lives.”

The safety profile for Imfinzi and FLOT chemotherapy was consistent with the known profiles of each medicine, and there were no new safety findings.

In a previously reported interim analysis for the key secondary endpoint of pathologic complete response (pCR), the Imfinzi combination more than doubled the pCR rate compared to neoadjuvant chemotherapy alone (19% versus 7%, odds ratio 3.08; p<0.00001).

Data will be presented at a forthcoming medical meeting and shared with global regulatory authorities.

Gastric and Gastroesophageal Junction (GEJ) Cancers

Gastric (stomach) cancer is the fifth most common cancer worldwide and the fifth-highest leading cause of cancer mortality. In many regions, its incidence is increasing in patients younger than 50 years old, along with other gastrointestinal (GI) malignancies. Nearly one million new patients were diagnosed with gastric cancer in 2022, with approximately 660,000 deaths reported globally.

GEJ cancer is a type of gastric cancer that arises from and spans the area where the esophagus connects to the stomach.

Disease recurrence is common in resectable gastric cancer patients despite undergoing curative-intent surgery and treatment with neoadjuvant/adjuvant chemotherapy. Approximately one in four patients who undergo surgery develop recurrent disease within one year, and one in four patients do not survive beyond two years, reflecting a high unmet medical need. Additionally, the five-year survival rate remains poor, with less than half of patients alive at five years.

MATTERHORN Trial

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).

The primary endpoint is event-free survival (EFS), defined as the time from randomisation until progression that precludes surgery or requires non-protocol therapy, local or distant recurrence, progression of disease, or death due to any cause as assessed by blinded independent central review (BICR) according to RECIST 1.1 and/or local pathology testing.

Imfinzi

Imfinzi (durvalumab) 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 approved in combination with chemotherapy (gemcitabine plus cisplatin) in locally advanced or metastatic biliary tract cancer (BTC) 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 non-small cell lung cancer (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 (etoposide and either carboplatin or cisplatin) for the treatment of extensive-stage SCLC.

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 SCLC, NSCLC, bladder cancer, breast cancer, several GI and gynaecologic cancers, and other solid tumours.