Merck drug extends immune system fight to stomach cancer
By Ben Hirschler MADRID (Reuters) - Merck & Co's drug Keytruda, the first in a new wave of immune-boosting medicines to be approved for treating melanomas in the United States, also has potential in stomach cancer, new research shows. Early clinical trial results reported on Sunday mean that gastric, or stomach cancer can be added to a growing list of tumor types where so-called immunotherapy may have an important role to play. Keytruda belongs to a drug class designed to help the body's own immune system fend off cancer by blocking a protein known as Programed Death receptor (PD-1), or a related target PD-L1, used by tumors to evade disease-fighting cells. On Sept. 4 it became the first drug of this type to win U.S. approval, although rivals including Bristol-Myers Squibb, Roche and AstraZeneca are working on similar products. While developed first for melanoma, these medicines are also showing promise in a range of other tumor types, including kidney, lung, bladder, and head and neck cancer. In a small Phase I study involving 39 patients with PD-L1 positive, advanced stomach cancer, a total of 12 people - or 31 percent - saw their tumors shrink after being given Keytruda, Kei Muro of Japan's Aichi Cancer Center Hospital told the European Society of Medical Oncology annual congress. Importantly, overall response rates were similar in Asian patients -- a population with a high rate of stomach cancer -- and non-Asian patients, Muro said. The Phase I clinical trial is continuing but at the time of analysis the duration of responses in individual patients ranged from more than eight weeks to more than 20 weeks. Merck said it planned to start a larger Phase II study in the first quarter of 2015 on the back of the encouraging data. Common adverse side effects included thyroid problems and fatigue, while serious grade 3-5 adverse events occurred in three patients. There was one treatment-related death. Immunotherapy is dominating the meeting of oncologists in Madrid as excitement builds about an approach that promises to push many cancer patients into remission by unleashing the power of their own immune systems to fight tumors. Further data on Merck's drug as a treatment for bladder cancer is also due to be released on Monday in Madrid. Some analysts believe the new immunotherapy drug class could generate more than $30 billion in annual sales worldwide by 2025 - a figure that reflects both the wide range of patients who could benefit and the high price of the medicines. The U.S. price for Keytruda is around $12,500 per month in melanoma patients, for whom the median duration of treatment has been 6.2 months. (Reporting by Ben Hirschler; Editing by Greg Mahlich)
