A New Treatment Option for CLDN18.2-Positive Advanced Gastric Cancer: One Patient’s Journey

For several years, Ms. Chen had been living with advanced gastric cancer. Surgery, chemotherapy and immunotherapy had helped at different stages, but the disease eventually progressed and her treatment options became increasingly limited.

By late 2024, her condition had deteriorated significantly. She was experiencing intestinal obstruction, peritoneal metastases, hydronephrosis, severe ascites and jaundice. Eating had become extremely difficult, and she relied largely on intravenous nutritional support.

Yet one result from an earlier pathology report would later become important: her tumor was HER2-negative but CLDN18.2-positive.

In 2025, as new treatment options targeting CLDN18.2 became available, that biomarker opened another possibility.

When an Unexpected Diagnosis Changed Everything

Ms. Chen was 40 when she was diagnosed in January 2022.

She had experienced recurrent stomach discomfort for some time, but worsening pain eventually led her to undergo gastroscopy. Initial findings suggested a relatively limited lesion, and surgery was recommended.

During the operation, however, the extent of the disease proved far greater than expected. Intraoperative pathology showed persistent positive margins, and a total gastrectomy was ultimately required.

Postoperative pathology confirmed poorly differentiated gastric adenocarcinoma with distant metastasis. The disease showed features of diffuse infiltrative gastric cancer, sometimes referred to as linitis plastica, which can spread extensively within the gastric wall even when the mucosal lesion appears relatively small.

Despite surgery and subsequent treatment, the cancer continued to progress.

A Biomarker That Did Not Yet Have a Treatment Option

Molecular and immunohistochemical testing showed that Ms. Chen’s tumor was HER2-negative and CLDN18.2-positive.

CLDN18.2 is a tight-junction protein normally found in differentiated gastric mucosal cells. In healthy tissue, it is largely concealed within tight junctions. When malignant transformation disrupts the normal tissue structure, CLDN18.2 may become exposed on the surface of tumor cells, making it a potential therapeutic target.

Today, CLDN18.2 is an increasingly important biomarker in gastric cancer. But in 2022, the finding did not immediately translate into an accessible targeted treatment for Ms. Chen.

She therefore received chemotherapy combined with immunotherapy. Her disease remained controlled for less than a year before treatment had to be interrupted after she developed immune-related pneumonitis.

Her condition subsequently worsened.

By April 2024, she had developed intestinal obstruction, peritoneal metastases, ureteral narrowing and hydronephrosis. Severe ascites and jaundice followed, and at one point her bilirubin level reached approximately 300 μmol/L. She could barely eat and required intravenous nutrition.

Searching for Another Option

Ms. Chen’s husband continued to follow developments related to CLDN18.2.

Through patient communities, he learned that a team led by Professor Zhou Jun, Medical Vice President and Director of Gastrointestinal Oncology at Shanghai GoBroad Cancer Hospital, affiliated with China Pharmaceutical University and part of GoBroad Healthcare Group (GoBroad), was working with emerging approaches for gastric cancer.

The couple met Professor Zhou in December 2024.

At that time, Ms. Chen weighed just over 30 kilograms, had very limited mobility and was experiencing incomplete intestinal obstruction. Her physical condition meant that she did not meet the eligibility criteria for the clinical study then under consideration.

The therapeutic window was narrow, but the team continued to assess whether another opportunity might become available.

In early 2025, a new treatment option targeting CLDN18.2-positive gastric cancer became available. Following a comprehensive assessment and clinical coordination, Ms. Chen began CLDN18.2-targeted therapy in February.

Treatment Adapted to the Patient

For Professor Zhou's team, identifying a potential treatment was only part of the challenge.

Years of cancer-related deterioration, previous therapies, total gastrectomy and severe nutritional impairment meant that Ms. Chen was unlikely to tolerate a conventional treatment schedule easily.

The team therefore developed an individualized treatment strategy based on her disease status, previous treatment history and physical condition. The treatment schedule was adjusted according to her response and tolerance, with close attention to adverse-event management and nutritional support.

Clinical improvement began to appear relatively soon.

A little over a week after treatment started, her bowel function began to recover. As gastrointestinal lesions decreased in size, the obstruction gradually improved and her pain became less severe.

After completing the second treatment cycle in March, she was able to eat semi-liquid foods again, including small amounts of finely prepared meat and shrimp.

For someone who had previously been unable to eat normally, these were meaningful changes in everyday function.

Why Biomarker Testing Matters

Ms. Chen’s experience also illustrates how the role of biomarker testing in gastric cancer is evolving.

When her CLDN18.2-positive result was first reported, there was no immediately available targeted treatment for her. Several years later, the same biomarker became relevant to a new therapeutic decision.

As precision treatment develops, identifying HER2, CLDN18.2 and other clinically relevant biomarkers can help physicians better understand which treatment strategies may be appropriate for an individual patient.

Accurate testing is therefore becoming an increasingly important part of treatment planning for advanced gastric cancer.

Returning to Everyday Life

By December 2025, Ms. Chen's daily life looked very different from the year before.

One morning at the hospital, she asked for pan-fried buns. Her husband bought six. She sat at the table and slowly ate four of them.

It was a simple breakfast, but after months in which normal eating had been nearly impossible, it represented something much more practical: she was once again able to enjoy food and participate in ordinary daily life.

Her treatment journey continues, and long-term outcomes require ongoing clinical follow-up. For Ms. Chen and her family, however, the progress has allowed them to start discussing plans that had once been put aside—including traveling together when her condition permits.

Her experience reflects an important development in gastric cancer care: as new targets and treatment approaches emerge, timely biomarker testing and individualized clinical assessment may create additional options for selected patients, even after previous treatments have become limited.

*This patient story describes an individual treatment experience. Treatment response and outcomes vary between patients. Medical decisions should be based on a comprehensive evaluation by qualified healthcare professionals.