If you or a loved one has been diagnosed with advanced stomach cancer or gastroesophageal junction (GEJ) cancer, you may hear about new targeted treatments being studied in clinical trials. One of these treatments is bemarituzumab, a medicine designed to treat a specific type of gastric cancer based on a tumor biomarker called FGFR2b.
This article explains what bemarituzumab is, who it may help, how it works, possible side effects, and what patients can expect.
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What Is Bemarituzumab?
Bemarituzumab is a type of targeted cancer treatment known as a monoclonal antibody. Unlike traditional chemotherapy, which attacks rapidly dividing cells, targeted therapies are designed to focus on specific features found on cancer cells.
Bemarituzumab targets a protein called FGFR2b. This protein is found at higher levels in some stomach cancers. Studies suggest that about 30% of HER2-negative gastric cancers may have increased FGFR2b expression (Wainberg et al., 2024).
If your tumor has high FGFR2b levels, it may respond differently to certain treatments. Bemarituzumab was developed to target cancers with this feature.
Who Might Benefit from Bemarituzumab?
Bemarituzumab has been studied in patients with:
- Advanced or metastatic gastric cancer
- Gastroesophageal junction (GEJ) adenocarcinoma
- HER2-negative tumors
- FGFR2b-positive cancer (confirmed by a lab test on tumor tissue)
In a clinical study called the FIGHT trial (Wainberg et al., 2024), bemarituzumab was given together with standard chemotherapy (mFOLFOX6) as first-line treatment.
The results showed that patients whose tumors had higher levels of FGFR2b (in at least 10% of cancer cells) had better outcomes compared with chemotherapy alone.
How Does Bemarituzumab Work?
Bemarituzumab works in two main ways:
- First, it blocks growth signals that cancer cells use to multiply.
- Second, it helps the immune system recognize and attack cancer cells that have FGFR2b.
This approach is different from chemotherapy, which works more broadly. Bemarituzumab is designed to work specifically in cancers that test positive for FGFR2b.
What Did the Clinical Trial Show?
In the FIGHT trial:
- Patients receiving bemarituzumab plus chemotherapy lived longer on average than those receiving chemotherapy alone.
- In patients with higher FGFR2b expression (≥10% of tumor cells), the median survival was about 24.7 months with bemarituzumab versus 11.1 months with chemotherapy alone.
- The cancer also stayed controlled longer in patients receiving bemarituzumab.
It is important to know that this was a phase 2 study. Larger phase 3 studies are ongoing to confirm these results.
How Is Bemarituzumab Given?
In the clinical trial, bemarituzumab was given as an intravenous (IV) infusion every two weeks, along with standard chemotherapy.
Treatment continued as long as the cancer was controlled and side effects were manageable. If this drug becomes widely approved in the future, the exact schedule may depend on final trial results and regulatory decisions.
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What Are the Possible Side Effects?
Like all cancer treatments, bemarituzumab can cause side effects. Most patients in the study experienced some side effects, especially since it was given together with chemotherapy.
The most important side effect seen with bemarituzumab was eye-related problems, especially corneal irritation. About two-thirds of patients experienced some type of eye side effect. These included:
- Dry eyes
- Blurred vision
- Eye discomfort
- Inflammation of the cornea
More severe eye side effects occurred in some patients. However, no life-threatening eye complications were reported in the study.
Other common side effects included:
- Nausea
- Diarrhea
- Fatigue
- Low white blood cell counts
- Decreased appetite
Because of the eye-related risks, patients receiving bemarituzumab may need regular eye examinations and close monitoring.
What Should Patients Expect?
If bemarituzumab becomes part of standard treatment, patients can expect:
- Tumor testing to check for FGFR2b levels
- IV infusions every two weeks
- Ongoing chemotherapy alongside the targeted therapy
- Close monitoring for side effects, especially eye symptoms
It is important to report any changes in vision, eye discomfort, or dryness to your healthcare team immediately. Not every patient with gastric cancer will qualify for bemarituzumab. The tumor must test positive for FGFR2b, and the treatment is currently still being studied in ongoing trials.
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Is Bemarituzumab Approved?
As of the latest available data from the FIGHT trial, bemarituzumab is still being evaluated in phase 3 clinical trials. These larger studies are needed to confirm whether it should become a new standard treatment. Patients interested in this therapy may ask their oncologist about clinical trial availability.
Why Biomarker Testing Matters
Modern cancer treatment increasingly relies on biomarker testing. Instead of treating all gastric cancers the same way, doctors now test tumors for specific features such as:
- HER2
- PD-L1
- FGFR2b
These biomarkers help doctors choose the most appropriate treatment for each patient. Bemarituzumab represents part of this shift toward personalized cancer care.
Final Thoughts
Bemarituzumab is a promising targeted therapy for patients with advanced gastric or gastroesophageal junction cancer whose tumors overexpress FGFR2b. In early studies, it improved survival and tumor response when added to chemotherapy, especially in patients with higher FGFR2b levels.
While more research is ongoing, bemarituzumab highlights an important step forward in precision medicine for stomach cancer.
If you have advanced gastric cancer, talk to your oncologist about biomarker testing and whether clinical trials targeting FGFR2b may be appropriate for you.