When cancer is resistant to a treatment it means the cancer cells aren't weakened or destroyed by the treatment any more. A study suggests that HER2-positive breast cancer cells resistant to Herceptin (chemical name: trastuzumab) may respond to Tykerb (chemical name: lapatinib). These results were reported at the 2010 American Association of Cancer Research annual meeting.
HER2-positive cancers make too much of the HER2 protein. The HER2 protein sits on the surface of cancer cells and receives signals that encourage breast cancer cells to grow and spread. About one out of every four breast cancers is HER2-positive. Both Herceptin and Tykerb work by blocking the HER2 protein's ability to make HER2-positive breast cancers grow.
Both Herceptin and Tykerb are targeted therapies. Herceptin is used to treat both early-stage and advanced-stage HER2-positive breast cancers. Tykerb is approved to be used in combination with the chemotherapy Xeloda (chemical name: capecitabine) to treat HER2-positive, metastatic breast cancers that have stopped responding to certain chemotherapy medicines and Herceptin. Tykerb also is approved to be used in combination with the hormonal therapy Femara (chemical name: letrozole) to treat postmenopausal women diagnosed with hormone-receptor-positive, HER2-positive, advanced-stage breast cancer.
This study was done in a lab on cells, not in people. The researchers identified specific proteins called biomarkers linked to both response and resistance to Herceptin and Tykerb. More research may help doctors understand how these biomarkers might be used when planning breast cancer treatment.
Stay tuned to Breastcancer.org's Research News to learn about new results that might help doctors develop new breast cancer treatments and better use the treatments we have now.