Targeted therapy medicines work on specific cancer cell characteristics that affect how the cells behave. For example, Avastin (chemical name: bevacizumab) blocks VEGF (vascular endothelial growth factor), a protein cancer cells make to grow new blood vessels (called angiogenesis). By blocking the VEGF protein, Avastin disrupts the growth of new cancer blood vessels and starves the cancer of nutrients it needs to grow.
Several small studies on targeted therapies were presented at the 2009 San Antonio Breast Cancer Symposium.
Nexavar studies: Nexavar (chemical name: sorafenib) is a targeted therapy medicine that blocks the actions of proteins that make cancers grow and spread. Nexavar is approved by the U.S. Food and Drug Administration (FDA) to treat advanced-stage liver and kidney cancer, and doctors wondered if it could treat advanced-stage breast cancer. Results were mixed.
Nexavar in combination with the chemotherapy medicine paclitaxel (brand names: Taxol and Abraxane) didn't seem to offer any benefits for women diagnosed with locally advanced-stage or metastatic breast cancer compared to paclitaxel alone. The length of time a woman lived without the cancer growing (progression-free survival) was longer in women who got Nexavar and paclitaxel (6.9 months) compared to women who got only paclitaxel (5.6 months). Still, this difference wasn't statistically significant, which means the difference could have been due to chance and not because of the Nexavar.
Compared to women who got paclitaxel alone, women who got both Nexavar and paclitaxel:
- responded in greater numbers to the treatment (68% compared to 54%)
- responded longer to treatment (5.6 months compared to 3.7 months)
Still, side effects -- some of them serious -- were more common in women who got Nexavar and paclitaxel compared to women who got paclitaxel alone (55% compared to only 7%).
Nexavar combined with the chemotherapy medicine Xeloda (chemical name: capecitabine) offered longer progression-free survival compared to Xeloda alone (6.4 months compared to 4.1 months).
When the combination of Nexavar and Xeloda or Xeloda alone was used as the first treatment for advanced-stage breast cancer, the difference in progression-free survival was larger: 7.4 months for women who got the combination compared to 4.1 months for women who got Xeloda alone.
Sutent studies: Sutent (chemical name: sunitinib) is a targeted therapy medicine that blocks the actions of other proteins that make cancers grow and spread. Sutent is approved by the FDA to treat certain advanced-stage kidney and intestinal cancers. So doctors wondered if it could treat advanced-stage breast cancer. Results suggest that Sutent doesn't work on breast cancer.
In women diagnosed with advanced-stage breast cancer, Sutent had shorter progression-free survival compared to Xeloda (2.8 months compared to 4.2 months). The study was stopped early when the researchers found that Sutent wasn't as effective as Xeloda.
Motesanib studies: Motesanib is a targeted therapy being studied as a treatment for a number of cancers, including breast cancer.
Women diagnosed with metastatic breast cancer were given one of three treatments:
- the combination of Avastin and paclitaxel
- the combination of motesanib and paclitaxel
- paclitaxel alone
There was no real difference in the number of women who responded to the Avastin combination compared to the motesanib combination:
- 52% for the Avastin-paclitaxel combination
- 50% for the motesanib-paclitaxel combination
But both were better than paclitaxel alone:
- 41% of the women responded to paclitaxel alone
There also was no difference in progression-free survival between the treatments. Serious side effect were more common in women who got motesanib than women who got Avastin or paclitaxel alone.
While these results may seem disappointing, it's clear that doctors are working hard to find more effective breast cancer treatments and better ways to use available medicines. Finding better ways to treat breast cancer is usually the result of many small steps that add up to bigger strides toward better care.