UPDATE 1-Astra drug shows glioblastoma promise-researchers

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LOS ANGELES, April 17 (Reuters) - An experimental cancer drug being developed by AstraZeneca Plc (AZN.L: Quote, Profile, Research) showed promise in treating a type of brain cancer, researchers said on Tuesday.

The mid-stage trial results show promise because the drug, known as AZD2171, normalized tumor vasculature and alleviated swelling in most of the glioblastoma patients treated with it, said the researchers from Massachusetts General Hospital and Harvard Medical School.

"This is a very promising outcome, but it definitely needs more follow up," said Dr. Tracy Batchelor, chief of neuro-oncology at Massachusetts General Hospital and lead investigator of the study, which was sponsored by the National Cancer Institute. He said the research team plans to start a Phase III trial of AZD2171 this year, funded by AstraZeneca.

The drug is an angiogenesis inhibitor designed to keep tumors from developing oxygen-carrying blood vessels, It interferes with a molecule called vascular endothelial growth factor (VEGF), which tells cells to grow new blood vessels.

Several anti-VEGF drugs have been developed by various companies, including Avastin from Roche (ROG.VX: Quote, Profile, Research) and Genentech (DNA.N: Quote, Profile, Research), an antibody-based drug which is already on the market.

The researchers said imaging and biomarker studies they performed as treatment was under way exposed a "window" during which the blood system feeding the tumor reverted to a more normal state, before changing again into the leaky, dilated vessels that make drug treatment difficult.

They also said the blood biomarker studies showed that as tumors stopped relying on VEGF to pump up blood flow to them they started using two other growth factors, neither of which had previously been recognized as important for human tumor blood vessel growth.