Adding Immunotherapy Before & After Surgery
- Promising new data presented at the 2025 ASCO conference indicates that adding a drug called durvalumab (brand name: Imfinzi) to the treatment plan for gastric (stomach) and gastroesophageal junction (GEJ) cancers in earlier stages could keep the disease under control for longer.
- The drug was added alongside the standard chemotherapy combination known as FLOT before and after surgery for gastric and GEJ cancers.
- Data from the phase III MATTERHORN trial showed it kept the cancer quiet for longer than chemotherapy alone, reducing the risk of disease progression or death by 29% for patients with early-stage and locally advanced disease.
- Dr. Sofya Pintova, a gastrointestinal medical oncologist at Mount Sinai Hospital in New York City, calls the data “practice-changing.”
The research looked into adding durvalumab to the standard chemotherapy combination known as FLOT before and after surgery for gastric and GEJ cancers. Data showed it kept the cancer quiet for longer than chemotherapy alone, reducing the risk of disease progression or death by 29% for patients with early-stage and locally advanced disease (stages II, III, and IVa). The findings came from the international phase III MATTERHORN trial, which followed almost 1,000 people with stage II to stage IVA disease.
Read MoreDurvalumab is the first immunotherapy to demonstrate significant event-free survival in a global, phase III setting.
Gastric Cancer: The Treatment Path
When cancer research is published, it can sometimes be difficult to interpret for patients and their families.
Here’s a refresher of terms you’ll need to know to understand the latest data.
- Resectable cancer means the tumor can be removed with surgery that aims for cure.
- FLOT combines four medicines: 5-fluorouracil, leucovorin, oxaliplatin, and docetaxel. Doctors give it every two weeks in the “neoadjuvant” window before surgery and again in the “adjuvant” window afterward.
- Durvalumab is an infusion given every four weeks that blocks PD-L1, a shield many cancers use to hide from immune cells.
- Event-free survival (EFS) counts the months until the first major setback, such as the cancer returning, growing through treatment, or causing death from any cause.
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 (around the time of surgery) 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 (operable).
More than two-thirds of the patients, 67.4%, treated with the durvalumab regimen remained event-free (no signs of progression) 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 overall survival, though the patients in the trial will continue to be observed to come up with final numbers later on.
Understanding PD-L1 and How Doctors Check It
PD-L1 stands for programmed death-ligand 1. Think of it as a “do-not-disturb” tag that some cancer cells hang on their surface. When immune cells bump into that tag, they back off instead of attacking. Drugs like durvalumab block the PD-L1 signal, pull the tag down, and let the immune system move in.
Tumors with higher PD-L1 levels often respond better to checkpoint inhibitors such as durvalumab. Knowing the PD-L1 score can help oncologists fine-tune treatment plans.
The following steps are involved in finding PD-L1 levels.
- Tissue sample. During your initial endoscopy or biopsy, the pathologist saves slivers of tumor tissue in wax blocks.
- Immunohistochemistry (IHC). The lab adds a special dye that sticks to PD-L1 proteins. Under the microscope, stained tumor cells light up brown.
- Scoring. The pathologist counts how many cancer cells (and sometimes nearby immune cells) carry brown stain and reports a percentage. Different studies use slightly different cutoffs, but a score of 1% or higher is often called “PD-L1 positive.”
- Turnaround time. Results usually come back within one to two weeks, well before chemotherapy starts.
If your pathology report already lists PD-L1, bring that page to your next visit. If it doesn’t, ask whether the existing biopsy can be retested or if a fresh sample is needed. The test is covered by most insurance plans, and many centers run it routinely for stomach and junction cancers now that immunotherapy has entered the playbook.
Questions To Ask Your Doctor
If you or a loved one has recently learned a stomach or GEJ cancer is resectable, you might soon hear about adding durvalumab to the usual chemo-plus-surgery plan.
Questions to discuss with your care team include:
- Am I eligible for durvalumab, and is it available at my treatment center?
- Will my insurance cover the added cost?
- How will we monitor for side effects?
- Will immunotherapy delay or complicate surgery?
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