According to an article recently published in the journal Cancer, patients with advanced gastric cancer who respond to a vaccine that stimulates the immune system to help fight cancer demonstrate significantly improved survival compared to patients who do not respond to the vaccine.
Cancer of the stomach, or gastric cancer, is the 14th most common cancer in the U.S. Unfortunately, only 10-20% of gastric cancer patients in the U.S. are diagnosed with early-stage cancer; the majority is diagnosed with advanced disease.
Metastatic gastric cancer refers to cancer that has spread to several and/or distant sites in the body. Treatment for metastatic gastric cancer is often not intended to cure the patient, but is rather aimed at improving their quality of life and extending their survival.
The main component of treatment for patients who cannot have their cancer surgically removed (unresectable), due to extent of spread or location of the cancer, is chemotherapy. Researchers continue to evaluate and compare new agents or regimens for the treatment of metastatic or unresectable gastric cancer in order to improve survival.
Gastrin is a hormone that is released when food enters the stomach; some foods seem to stimulate the production of gastrin more than others. Cells, called G cells, that are found in the stomach lining produce gastrin, which is released into the bloodstream. When blood levels of gastrin reach a certain level, gastric acid is released to help break down and digest the food. Gastrin may also affect other parts of the digestive system, such as the pancreas, liver, and intestines.
Gastrin has also been shown to stimulate the growth of various types of cancer cells, including gastric cancer cells. These cells overexpress genes and receptors (proteins) that are very sensitive to the stimulatory effects of gastrin. G17 is the predominant form of gastrin and circulates throughout the body. G17 is thought to reduce the cancer-killing effects of some chemotherapy agents on gastric cancer cells.
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Researchers from five different countries recently conducted a multi-institutional clinical trial evaluating a vaccine, called G17DT, in the treatment of gastric cancer. G17DT stimulates immune cells in the patient’s body to attack cancerous cells displaying gastrin receptors.
This trial included patients with metastatic or unresectable gastric cancer. Patients were treated with G17DT in addition to the chemotherapy agents 5-fluorouracil and Platinol® (cisplatin).
- Patients who responded to G17DT had significantly improved survival over those who did not respond to the vaccine.
- Overall anticancer response rate to treatment was 30%.
- Median time to cancer progression was 5.4 months.
- Median survival was nine months.
- Patients who responded to the vaccine, as determined through blood tests, had a significantly longer time to cancer progression than those who did not respond to the vaccine.
- Patients who responded to the vaccine had a median survival time of 10.3, versus only 3.8 months for those who did not respond to the vaccine.
- There were no serious side effects associated with the vaccine.
The researchers concluded that the addition of the vaccine GD17, which is still in clinical trials, to chemotherapy may improve survival without serious side effects for some patients who respond to the vaccine. The authors state that a phase III trial (phase of trial prior to FDA review) is warranted to further evaluate the potential for improved survival among patients with advanced gastric cancer.
Patients with advanced gastric cancer may wish to speak with their physician about their individual risks and benefits of participating in a clinical trial further evaluating GD17 or other promising therapeutic approaches. Two sources of information regarding ongoing clinical trials include the National Cancer Institute (www.cancer.gov) and www.cancerconnect.com.
Reference: Ajani J, Hecht J, Ho L, et al. An Open-Label, Multinationa, Multicenter Study of G17DT Vaccination Combination with Cisplatin and 5-Fluorouracil in Patients with Untreated, Advanced Gastric or Gastroesophageal Cancer: The GC4 Study. Cancer. 2006; 106: 1908-1916.