Study: Revoked breast cancer drug increased tumor-forming cells

Jan 25, 2012

University of Michigan researchers say a drug used to treat advanced breast cancer actually led to an increase in the number of tumor-forming cells.  The FDA revoked its approval of the drug last year.

The drugs Avastin and Sutent were used to shrink tumors and slow the progress of breast cancer.  But the effects didn’t last and when the tumors returned, they were more aggressive.

Dr. Max Wicha is director of U-of-M’s Comprehensive Cancer Center.

He says their research showed the drugs choke off blood supply to the tumor, but had an unintended consequence: They also cut off oxygen to the tumor.

"That deprivation of oxygen stimulates the cancer stem cells, and that's why the tumors become more aggressive, and the patients don't live longer," Wicha says.

He says researchers are now looking at whether Avastin and Sutent could be used with other drugs to knock out cancer stem cells.

He says understanding the biology of what’s happening in cancer will give clues to why some treatments work or don’t work  and how they can be improved.

Avastin is approved for use in other types of cancer.

Results of the study appear online in the Proceedings of the National Academy of Sciences Early Edition.