Cancer Drug Found to Promote Tumor Growth

A new anti-cancer drug actually promotes tumor growth at lower doses, according to a study conducted by researchers from the Institute of Cancer and published in Nature Medicine. This means that as the body removes large doses of the drug from its system, leaving behind successively smaller doses, the cancer-promoting characteristics of the drug kick in. "We've got evidence now that low doses can enhance tumor growth," said lead researcher Kairbaan Hodivala-Dilke. "So there is no benefit of giving a high dose, which then drops, and then a high dose again." The study was conducted on the drug cilengitide, an anti-angiogenesis drug in the same class as the anti-cancer medicines Avastin and Sutent. It is intended to prevent the cells in blood vessels from moving or sticking together, a critical part of the process that allows tumors to develop their own blood vessels (angiogenesis) and thereby support unlimited growth. The researchers found that when mice were given low doses of cilengitide, a molecule known as VEGFR2 was activated, which stimulated angiogenesis and led to accelerated tumor growth. Cilengitide has been tested on patients with brain tumors, but has proven effective in only a few cases. Hodivala-Dilke suggested, based on the new findings, that the drug might be more effective if given by an infusion pump that keeps levels in the body continually high. Avastin is approved for the treatment of colorectal cancer, while Sutent is used for kidney cancer. Both drugs currently extend life by an average of a few months, but have also been known to inexplicably fail. Researchers now suspect that like cilengitide, they might be promoting tumor growth as they break down. "Sutent and Avastin have proven effective enough for use ... but there is still need to understand why they can sometime fail," said Lesley Walker of Cancer Research UK. "It may be that there are similar mechanisms at work." Sources for this story include: news.bbc.co.uk. www.naturalnews.com