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Cancer 'wonder' drug might not be effective in early stages

| Sunday, May 31, 2009

A "wonder" drug that fights breast, lung and colon cancer by cutting off blood supply to tumors doesn't seem to pack the same punch in colon cancer caught early, according to research from Allegheny General Hospital presented Saturday at a national cancer conference in Florida.

Avastin, made by pharmaceutical giant Roche's Genentech unit, did not improve the three-year survival rate in patients with early stages of colon cancer when compared with patients receiving standard chemotherapy, scientists said at the annual meeting of the American Society of Clinical Oncology in Orlando.

"It's been approved for advanced cancer, and it was hoped that moving it into early stage colon cancer would increase the rate of cures," said Allegheny General oncologist Dr. Norman Wolmark, lead researcher on the study. "And it didn't."

Through the National Surgical Adjuvant Breast and Bowel Project, based at Allegheny General, doctors at more than 250 hospitals worldwide recruited 2,710 early-stage colon cancer patients. Half were treated with one year of Avastin and chemotherapy; half received just chemotherapy.

Avastin is known by the generic name bevacizumab. Potential side effects include development of a hole in the stomach and bleeding problems that can hamper wound healing. Few patients experienced side effects in the clinical trial, with high blood pressure being the major problem, Wolmark said. Genentech helped pay for the clinical trial, as did the National Cancer Institute.

Though both groups of patients ultimately had the same outcome — about 75 percent lived three years without recurrence of cancer — patients on Avastin had 40 percent fewer cancer recurrences during the year they took the drug.

"While it was being given, it was effective," Wolmark said. "But after it was discontinued, the benefit disappeared, raising the extremely important question whether giving it over a longer period of time would increase the benefit."

Genentech is awaiting results of eight clinical trials to determine whether Avastin can reduce recurrence of other cancers, such as breast and lung, said spokeswoman Kristina Becker.

"We believe the results support the theory that Avastin may be an important medicine to help prevent early-stage colon cancer from returning," she said in an e-mail. "The results provide valuable insights for future trials and we are committed to ongoing and future studies of Avastin in early-stage cancer."

Wolmark's team is considering conducting another clinical trial that would increase the time span during which Avastin is given for adjuvant care from one year to two or more.

"At this point I think everybody is enthusiastic about a trial that would use bevacizumab for two years," Wolmark said. "But like any drug used over a long period of time, the risk of noncompliance increases. With each additional year, the number of patients that stop taking it grows and that's not trivial."

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