IMPAKT: Estrogen receptor status may explain some resistance to therapy in women with HER2-positive breast cancer

May 7, 2010

Researchers have discovered molecular evidence that may explain why some women with HER2-positive breast cancer do not respond to drugs designed to target this molecule.

The research, presented at the IMPAKT Breast Cancer Conference in Brussels, Belgium,  looked at data from nearly 2000 patients to determine if estrogen receptor status plays a part in the biology of HER2-positive breast cancer and response to therapy.  The researchers found that estrogen receptor status of HER2-positive breast cancer seems to be correlated with different responses to anti-HER therapies.  Patients with ER+/HER2+ compared with ER-/HER2+ breast cancers may actually benefit more from drugs that inhibit the P13K/AKT molecular pathway, while inhibition of the the estrogen receptor may actually result in worse outcome for the patients.  This may help explain why women with HER2+ cancer who are given hormonal therapy along have poorer outcomes, say the researchers.  Read more in a press release from the European Society for Medical Oncology (ESMO).