The analysis evaluated patient benefit according to the level of HER2 identified in their stomach tumour. Overall survival for patients with high levels of HER2 receiving Herceptin was 16 months on average versus 11.8 months for patients receiving chemotherapy alone.These results were presented at the joint 15th Congress of the European CanCer Organisation (ECCO) and 34th Congress of the European Society for Medical Oncology (ESMO) in Berlin, Germany. They illustrate the importance of an individualized approach to patient care and the opportunity that a targeted medicine may offer.
The rationale for conducting this trial was based on the knowledge that the targeted therapy trastuzumab has demonstrated unprecedented efficacy in the treatment of HER2-positive breast cancer. In addition, the overexpression of HER2 was also observed in stomach cancer.
In the ToGA study, patients were randomized to receive one of the following regimens as their first line of treatment:
- A fluoropyrimidine (capecitabine or intravenous 5-FU) and cisplatin every 3 weeks for 6 cycles. Most patients were receiving Xeloda and cisplatin as chemotherapy
- Trastuzumab 6mg/kg every 3 weeks until disease progression in combination with a fluoropyrimidine and cisplatin which was stopped after a maximum of for 6 cycles
The primary objective of the study was to demonstrate superiority in overall survival of the trastuzumab containing treatment arm compared to the chemotherapy alone arm. The pre-planned interim analysis was triggered by the occurrence of 347 events. Secondary endpoints for the study included progression-free survival, overall response rate, duration of response, safety and quality of life. In the ToGA study, no new or unexpected side effects were observed.
For overall survival, the Hazard Ratio was 0.74 (CI 0.60, 0.91) with a highly significant p-value of p=0.0046 corresponding to a 26% reduction in the risk of death. All patients who were included the study to receive trastuzumab had a median overall survival increase by 2.7 months to 13.8 months. The response rate was increased with trastuzumab from 34.5 % to 47.3%. Patients with tumors exhibiting higher levels of HER2 experienced even greater benefit from the addition of trastuzumab.
“It is now clearly proven that Herceptin prolongs the lives of patients suffering from HER2-positive gastric cancer. As an investigator on this study and a treating physician, it is very rewarding to see a new effective treatment option emerging”, said principle investigator, Professor Eric Van Cutsem, University Hospital Gasthuisberg, Leuven, Belgium. “The results of the ToGA study reinforce the need for early and accurate HER2 testing of all advanced gastric cancer patients.”
Based on the significant findings of the ToGA study, Roche has submitted a label extension application with the EU Health Authorities for use of trastuzumab in HER2-positive advanced gastric cancer. Applications for label extension in other regions of the world will follow as soon as possible.
“We are pleased to see the impressive benefit that the targeted therapy Herceptin provides for patients with HER2-positive stomach cancer. That this benefit is even greater in patients with higher levels of HER2demonstrates the significant advances through personalized medicine”, commented William M. Burns, CEO of Roche’s Pharmaceuticals Division, “Herceptin will become the new standard of care and will make an important contribution to helping these patients.”
Stomach cancer is the second most common cause of cancer-related death worldwide with over 1,000,000 new cases diagnosed each year. Stomach cancer is associated with poor prognosis and early diagnosis is challenging because most patients do not show symptoms until the later stages. Around 16% of stomach tumors express high levels of HER2 (IHC 3+ or IHC2+/FISH+).
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