The study (called the ToGA study) was led by Eric Van Cutsem, a professor at the University Hospital Gasthuisberg, Leuven, Belgium and was presented at the annual meeting of the American Society of Clinical Oncology which is being held in Orlando Floriday from 29 May to 2 June.
Patients diagnosed with advanced stomach (gastric) cancer generally do not have a good prognosis, the median survival time after initial diagnosis is about 10 months with current standard therapies.
In an international phase III study sponsored by Roche, the drug company that markets Herceptin, Van Cutsem and colleagues found that adding Herceptin (trastuzumab) to standard chemotherapy (Xeloda or intravenous 5-FU and cisplatin) helped patients with HER2-positive stomach cancer live a median of 13.8 months compared with 11.1 months for those who had standard chemotherapy on its own.
The trial enrolled 594 patients who tested positive for HER2 tumors from a group of about 3,800 patients with inoperable locally advanced, recurrent and/or metastatic stomach cancer.
The study was done because Herceptin is known to be effective at targeting breast tumors that over-express HER2 and the investigators wanted to know if it might be effective in stomach cancers that also over-express HER2. Herceptin, a humanized antibody, is a targeted therapy that interferes with molecules that help HER2-positive tumors to grow.
HER2 is a gene that expresses a protein called Human Epidermal growth factor Receptor 2 that is is responsible for making tumors aggressive by controlling the signalling pathways for cell growth and differentiation.
The patients were randomized to one of two groups. One group received a fluoropyrimidine (Xeloda or intravenous 5-FU) and cisplatin every 3 weeks for 6 cycles, mostly in the form of a chemotherapy.
The other group received Herceptin 6mg/kg every 3 weeks until progression, in additon to the fluoropyrimidine and cisplatin therapy for 6 cycles.
The results also showed that:
- Herceptin reduced the risk of death in patients with HER2-positive advanced and inoperable stomach cancer by 26 per cent compared to patients who were not given the drug.
- Patients with tumors showing high levels of HER2 benefited even further from treatment with Herceptin: their survival was extended to an average of 16 months.
In a prepared statment from Roche, Van Cutsem said there was a high “unmet medical need” in advanced forms of stomach cancer, and the study shows that using Herceptin as a targeted therapy contributes enormously to advancing therapy in this area.
“To see this unprecedented survival benefit for patients with HER2-positive stomach cancer is enormously rewarding,” said Van Cutsem.
Every year more than 1 million people find out they have stomach cancer, which is the second most common cause of cancer-related death worldwide.
Symptoms don’t show in the early stages, making the disease a difficult one to diagnose soon enough to allow early treatment that would improve prognosis.
HER2-positive stomach cancer accounts for about 22 per cent of stomach cancers: this is the same in Europe and Asia where the disease is most prevalent.
CEO of Roche’s Pharmaceuticals Division, William M Burns, said that Herceptin had been an enormous benefit to women with HER2-positive breast cancer, and the company was “extremely pleased to see its impressive benefit extending to patients with stomach cancer”.
“The targeted therapy Herceptin will become the new standard of care and we can make an important contribution in helping these patients live longer,” he added.
Herceptin is sold in the US Genentech, in Japan by Chugai and internationally by Roche.
Worldwide, nearly 600,000 patients with HER2-positive breast cancer have been treated with Herceptin since 1998.
Main source: Roche.
Written by: Catharine Paddock, PhD