Trastuzumab effective in some breast tumors with undetectable HER-2

[Becky]

This is very interesting especially when thinking about how these pathways may be interconnected.



Regards



Becky



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NEW YORK (Reuters Health) - Trastuzumab (Herceptin) plus cisplatin is effective against breast cancer cells with low or undetectable HER-2 expression but with overexpression of the growth factor heregulin (HRG). In a study conducted at Northwestern University in Chicago, Illinois, researchers report that activation of HER-2 by HRG in breast cancers with low or undetectable HER-2 expression makes these tumors more resistant to cisplatin.

As reported in the August 10th Journal of Clinical Oncology, Dr. Ruth Lupu and colleagues engineered breast cancer cells with low HER-2 to overexpress HRG, which made them "10-fold more resistant to the alkylating agent cisplatin." The researchers found that co-exposure to trastuzumab completely reversed HRG-promoted resistance to chemo.

Trastuzumab is known to act synergistically with cisplatin and other agents such as docetaxel, paclitaxel and vinorelbine against HER-2-positive breast cancers. The team concludes this therapeutic approach can also be "extremely efficient without HER-2 overexpression."

Dr. Lupu told Reuters Health that "this is a completely new avenue of use of Herceptin in metastatic breast cancer."

Assessment of HRG expression could identify a breast cancer population with HER-2-negative tumors that might benefit from trastuzumab. "This approach makes about 30% more cases of breast cancer benefit from these chemotherapy agents," Dr. Lupu said.