The global gastric cancer community recently came together for an international post-ASCO 2026 review webinar co-hosted by leading patient advocacy organisations, including Debbie’s Dream Foundation, the Gastric Cancer Foundation, No Stomach For Cancer, Hope for Stomach Cancer, My Gut Feeling, and Stomach Cancer UK.

The webinar featured an overview of the most important gastric cancer updates presented at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting by Dr Yelena Janjigian of Memorial Sloan Kettering Cancer Centre. This was followed by a discussion with Dr Samuel Klempner of Harvard Medical School, Dr Elena Elimova of Princess Margaret Cancer Centre, and gastric cancer patient advocate Frank Blandon.

Together, they explored how the latest research could influence treatment decisions, access to care, and the day-to-day realities faced by people living with gastric cancer.

A Major Advance for HER2-Positive Gastric Cancer

One of the most significant developments presented at ASCO 2026 came from the HERIZON-GEA-01 trial, which focused on HER2-positive gastric cancer, a subtype driven by excessive HER2 protein activity that promotes tumour growth.

Treatment for HER2-positive gastric cancer has evolved considerably over the past decade. The introduction of trastuzumab alongside chemotherapy marked the first major breakthrough. More recently, immunotherapy was added to treatment for some patients, although its benefits were largely limited to those whose tumours expressed the PD-L1 biomarker.

New results presented this year suggest that a treatment combination including zanidatamab, chemotherapy and immunotherapy may offer even greater benefits.

Zanidatamab is a bispecific antibody, meaning it is designed to target two areas of the HER2 protein simultaneously. The study showed improved overall survival compared with previous standards of care and, importantly, benefits were observed regardless of PD-L1 status.

For patients, this could represent a significant step towards more effective treatment options for HER2-positive disease.

New Possibilities Around Surgery

For patients with earlier-stage gastric cancer who are eligible for surgery, experts discussed two important studies: MATTERHORN and ASTRUM-006.

MATTERHORN Trial

The MATTERHORN study evaluated the addition of the immunotherapy drug durvalumab to the standard FLOT chemotherapy regimen before and after surgery.

Results continue to demonstrate improved outcomes, including a 6% absolute improvement in overall survival at three years. While all patient groups appeared to benefit, the greatest benefit was observed among patients with PD-L1-positive tumours.

ASTRUM-006 Trial

Not all patients can tolerate the intensive FLOT regimen. For these individuals, ASTRUM-006 offers a potential alternative.

The study combined a less intensive chemotherapy approach with immunotherapy and demonstrated encouraging results, particularly among patients with PD-L1-positive disease.

However, the discussion also highlighted an important question increasingly faced by patients worldwide: how long should immunotherapy continue after surgery?

Dr Elimova noted that in some countries, including Canada, extended post-surgical immunotherapy may not be reimbursed, creating significant financial burdens for patients and families.

Emerging Targets: MET and KRAS

Researchers are also making progress against less common but challenging tumour types.

MET-Amplified Tumours

MET amplification occurs in approximately 5% of gastric cancers and is associated with more aggressive disease.

Early data combining standard treatment with the targeted therapy savolitinib has shown encouraging tumour responses. Much of this research is currently being conducted in Asia, with further studies expected in the coming years.

KRAS Alterations

Several new KRAS-targeted therapies are being investigated, and early results are promising. While these treatments remain experimental, they represent an important area of future development.

The discussion also highlighted the growing importance of comprehensive biomarker testing and next-generation sequencing (NGS). Although access remains inconsistent across countries, these tests can help identify treatment options and clinical trial opportunities.

Metastatic Disease: Refining Immunotherapy Strategies

Researchers continue to explore whether combining different immunotherapies can further improve outcomes.

While some newer approaches, including bispecific antibodies such as cadonilimab, have generated excitement, results from the ATTRACTION-06 trial showed that combining nivolumab and ipilimumab with chemotherapy did not improve overall survival in the first-line setting.

As a result, dual checkpoint blockade is not yet considered a standard first-line treatment for metastatic gastric cancer. Nevertheless, research in this area continues.

The Patient Perspective: Frank Blandon’s Experience

A particularly powerful part of the webinar came from Frank Blandon, who shared his experience of living with stage IV gastric adenocarcinoma.

Currently receiving capecitabine maintenance therapy, Frank highlighted several challenges that are often difficult to capture in clinical trial results.

The Fear of Stopping Treatment

While doctors regularly discuss when treatment can safely be stopped, patients may experience significant anxiety at the thought of ending a therapy that has kept their cancer under control.

Frank described how continuing treatment can provide reassurance and a sense of security, even when difficult decisions about long-term management arise.

Living with Side Effects

Frank also discussed the reality of managing treatment-related side effects.

During previous treatment with FOLFOX, he developed severe neuropathy that required discontinuation of oxaliplatin. Today, he manages hand-foot syndrome caused by capecitabine through daily supportive care.

His experience highlights that successful cancer treatment often involves ongoing management of side effects as well as the cancer itself.

The Importance of Testing

Frank emphasised the value of comprehensive biomarker testing throughout the treatment journey. Such testing not only helps guide current treatment decisions but may also identify future treatment options and clinical trial opportunities.

Looking Ahead: The Promise and Challenges of Liquid Biopsies

Experts also discussed the growing interest in circulating tumour DNA (ctDNA) testing.

These blood-based tests have the potential to detect minimal residual disease following surgery and could eventually help determine which patients require additional treatment and which may safely avoid it.

However, Dr Elimova cautioned that ctDNA testing has not yet been validated for routine treatment decision-making in gastric cancer. Furthermore, detecting microscopic traces of cancer months before they become visible on scans may create additional anxiety for some patients.

Key Takeaway

ASCO 2026 delivered encouraging news for people affected by gastric cancer. New targeted therapies such as zanidatamab are improving outcomes for HER2-positive patients, advances in perioperative treatment are increasing the chances of cure, and emerging biomarkers continue to move the field towards more personalised care.

At the same time, the discussion served as an important reminder that treatment decisions extend beyond clinical data. Access to care, treatment costs, side effect management, and the emotional realities of living with cancer remain central to the patient experience.

To learn more about the studies discussed, visit the ASCO 2026 Annual Meeting coverage.

Author:

Giusy Rizzo