Earlier today, Roche announced positive results from a phase III study evaluating its breast cancer blockbuster, Herceptin, in gastric cancer. According to Roche, the addition of Herceptin to standard chemotherapy “significantly prolonged” overall survival of gastric cancer patients. From a medical perspective, this trial is a great achievement considering the severe shortage of effective treatments for gastric cancer. This is also the first success Herceptin has outside of breast cancer, where it quickly became a cornerstone treatment.
Similarly to the case in breast cancer, the gastric cancer trial (The Toga study) included only patients whose tumors express Herceptin’s target, the Her-2 protein. The idea of distinguishing between patients based on the biology of their tumors has become the standard in many cancer trials, particularly when targeted therapies such as Herceptin are involved. The Toga trial further validates this approach, and proves yet again that homing in on a genetically defined subgroup of patients may decrease a drug’s addressable market, but increases chances of showing a real benefit.
This trial is very good news for Roche, which just last week closed the deal to acquire 44% of Genentech (DNA) that it does not already own for $95 a share. Although gastric cancer is not as prevalent in developed countries as breast cancer, it represents a large market with high demand for new treatments. In particular, to date, no targeted agents have been approved for the treatment of the disease, leaving the stage to a handful of chemotherapy regimens. Herceptin may be the first targeted agent to become approved in gastric cancer, but its exclusivity might not last for long, as results from several highly anticipated phase III trials are expected in the coming 12 months. Most notable is a trial evaluating Avastin with chemotherapy (AVAGAST), which, in contrast to the Herceptin trial, does not seem to use special selection criteria.
Gastric cancer is the second leading cause of cancer related death in the world with developing countries accounting for approximately 70% of cases. In developed countries, almost 340 thousand people are diagnosed with the disease every year. In the US, gastric cancer is less common, whereas in Japan, gastric cancer occurs nearly five times more frequently, which makes Japan the most important market for gastric cancer. In an analysis conducted last year as part of the screening process for the Toga trial, investigators found that approximately 22% of patients with gastric cancer express Her-2.
