Immunotherapy Amplifies Response

  • Promising new data presented at the 2025 ASCO conference indicate that adding durvalumab (Imfinzi) to the treatment plan for gastric and gastroesophageal junction (GEJ) cancers could keep the disease under control for longer.
  • The drug was added alongside the standard chemotherapy combination, FLOT, before and after surgery for gastric and GEJ cancers and was shown to improve event-free survival.
  • More than two-thirds of the patients, 67.4%, treated with the durvalumab regimen remained event-free at two years after starting the treatment compared to 58.5% in the control group.

Promising data presented at the 2025 American Society of Clinical Oncology (ASCO) meeting in Chicago indicate that adding immunotherapy drug durvalumab (brand name: Imfinzi) to the treatment plan for gastric and gastroesophageal junction (GEJ) cancers could keep the disease under control for longer.

The research looked into adding durvalumab to the standard chemotherapy combination, FLOT, before and after surgery for gastric and GEJ cancers. Data showed it kept the cancer quiet for longer than chemotherapy alone. The findings came from the international phase III MATTERHORN trial, which followed almost 1,000 people with stage II to stage IVA disease.

The data will lead to “a big shift in the standard of care,” Dr. Sofya Pintova, a gastrointestinal medical oncologist at Mount Sinai Hospital in New York City, tells SurvivorNet Connect. It’s expected to be practice-changing.

While the final data on overall survival (OS) will not be released for a few months, Dr. Pintova explains that the results look very positive for patients with localized disease.

“It looks like a very positive study that will confirm overall survival benefits and will benefit a lot of patients,” she says. “We will be able cure more patients with this strategy.”

To assess how effective the approach was, researchers looked a event-free survival (EFS) and pathologic complete response (pCR) in removed tissue.

What Did The Data Show?

The results of the MATTERHORN phase III trial, which were presented at the ASCO conference on June 1, show giving durvalumab as a perioperative treatment in combination with FLOT chemotherapy reduced the risk of disease progression, recurrence, or death by 29% vs. chemo alone for patients with gastric or GEJ cancers that were considered resectable.

More than two-thirds of the patients, 67.4%, treated with the durvalumab regimen remained event-free at two years after starting the treatment compared to 58.5% in the control group.

This is the first and only immunotherapy to show significant event-free survival for this group of patients in a global, phase III study.

Researchers also observed a benefit in OS, though the patients in the trial will continue to be observed to come up with final numbers later on.

Dr. Rodrigo C. Leão Edelmuth is a board certified digestive surgeon at Hospital Israelita Albert Einstein in São Paulo, Brazil. He holds his General Surgery and Digestive Surgery degree from São Paulo University Medical School. He underwent a postgraduate course on Surgical Leadership at Harvard Medical School and a Research Fellowship in the Department of Surgery at Weill Cornell Medicine in New York. Dr. Edelmuth is member of the Society of American Gastrointestinal and Endoscopic Surgeons (SAGES) and of the Society for Surgery of the Alimentary Tract (SSAT). In 2022 he received the SAGES Career Development Award. Read More