Researchers are continually working to find better ways to treat all stages of breast cancer. Several studies offer very early results on a number of new ways to treat breast cancer. The results were reported at the 2008 San Antonio Breast Cancer Symposium.
Some of these studies were phase I studies, which means the potential treatment is tested in a very small group of people (less than 100) to make sure it's safe and figure out a safe dosage, and to evaluate side effects. Some of the studies were phase II studies, which means the new treatment was given to between 100 and 300 people to make sure it works and to further study its safety. If the results from phase II trials look promising, researchers will conduct phase III trials, which means the new treatment is given to a larger group of people (more than 1,000) to confirm that it works and to see whether it's more effective than commonly used treatments. These phase I and phase II results, while promising, are very early results and the treatments reviewed here will not be available until more research is done.
New Treatments Shown to be Effective in Treating Breast Cancer
mTOR (Mammalian Target of Rapamycin) Inhibitors: Cancer cells need energy to grow and spread. A kinase is a kind of protein that helps all cells (both normal and cancer cells) get the energy they need. Doctors know that when kinases don't act normally they help certain breast cancers grow. Herceptin (chemical name: trastuzumab) treats breast cancer by interfering with this abnormal kinase activity.
mTOR is a kinase and doctors think it helps some breast cancers grow. RAD001 is an experimental targeted therapy that interferes with mTOR activity. In a phase I trial, 20 of 27 metastatic breast cancers responded to a combination of Taxol (chemical name: paclitaxel), Herceptin, and RAD001. But in a phase II trial, only 3 of 31 metastatic breast cancers responded to treatment with only RAD001.
TAS-108: Estrogen can make hormone-receptor-positive breast cancers grow and spread. Hormonal therapy medicines either reduce the amount of estrogen in the body or block estrogen's effect on breast cancer cells. Still, some advanced-stage breast cancers that have responded to available hormonal treatments can stop responding to those treatments.
TAS-108 is an experimental hormonal therapy medicine. In women diagnosed with advanced-stage breast cancer that had stopped responding to available hormonal therapy medicines, researchers found that some of the cancers did respond to TAS-108.
Zolinza (chemical name: vorinostat): Zolinza is a medicine that interferes with a protein that controls genetic activity inside a cancer cell. In a very small, very early study involving women diagnosed with advanced-stage breast cancer, researchers found that many of the cancers responded to a combination of Zolinza, Taxol, and Avastin (chemical name: bevacizumab).
Abraxane (chemical name: albumin-bound or nab-paclitaxel): Abraxane is a newer form of paclitaxel. Both Taxol and Abraxane are approved to treat advanced-stage breast cancer. Paclitaxel has to dissolve so it can enter the bloodstream. But paclitaxel does not dissolve in water. Taxol, the older form of paclitaxel, dissolves paclitaxel in a solvent called Cremaphor. But Cremaphor can cause an allergic-like reaction during treatment.
Instead of dissolving paclitaxel in Cremaphor, Abraxane surrounds the paclitaxel with albumin, a human protein. Because Abraxane doesn't use Cremaphor, it doesn't cause the allergic-like reaction seen with Taxol.
A small, early study found that most of the 123 women diagnosed with stage II or stage III breast cancer and treated with Abraxane and the chemotherapy medicines Gemzar (chemical name: gemcitabine) and Ellence (chemical name: epirubicin) got some benefits from the treatment.
Some breast cancers produce too much of a protein called SPARC. Researchers wondered if too much SPARC on the surface of breast cancer cells was connected to worse prognosis. SPARC can bind to albumin, so this study also looked to see if Abraxane would be more effective against cancers with too much SPARC because Abraxane surrounds paclitaxel with albumin. But the results showed no connection between too much SPARC and worse prognosis. The results also found that Abraxane wasn't more effective against breast cancers with too much SPARC.
Ixempra (chemical name: ixabepilone): Ixempra is approved to treat advanced-stage breast cancer after other chemotherapy treatments have stopped working. Ixempra is given alone or in combination with the chemotherapy medicine Xeloda (chemical name: capecitabine).
A small, early study looked at using Ixempra in combination with Herceptin to treat HER2-positive, metastatic breast cancer. Of 39 women treated with Ixempra and Herceptin, 20 of the women got some benefit from the combination. In 10 of the other women, the cancer stopped growing while being treated with Ixempra and Herceptin.
Potential New Breast Cancer Treatments
IGF Receptor Inhibitors: All cells have different types of receptors on their surfaces. These receptors tell the cell when to grow and divide based on chemical signals. But hormone receptors on the surface of many breast cancer cells can work with another receptor called IGF-R1 (insulin-like growth factor type 1). Together, these two receptors make breast cancers grow and spread. Doctors think that blocking the IGF receptor might make advanced-stage breast cancers respond better to hormonal therapy medicines.
An early safety study involving a small number of women diagnosed with advanced-stage hormone-receptor-positive breast cancer found that combining an experimental IGF receptor inhibitor called CP-751,871 with the hormonal therapy medicine Aromasin (chemical name: exemestane) didn't cause any severe side effects or problems. Some of the women treated with CP-751,871 developed high blood sugar, liver problems, or headaches. More research is needed to see if an IGF receptor inhibitor can effectively treat advanced-stage hormone-receptor-positive breast cancer.
PARP Inhibitors: DNA is the genetic code inside of a cell. Breast cancer cells are more likely than normal cells to have damaged DNA. Some chemotherapy medicines work by damaging breast cancer cells' DNA. Still, cells can repair the damage. A protein called PARP helps cells repair DNA damage. Researchers have found that PARP levels are higher than normal in some cancer cells, including breast cancer cells. This could make it easier for a breast cancer cell to recover from damage caused by chemotherapy.
BSI-201 is an experimental medicine that interferes with PARP's ability to repair DNA damage. An early safety study involving a small number of women diagnosed with advanced-stage, triple-negative (estrogen-receptor-negative, progesterone-receptor-negative, and HER2-negative) breast cancer found that adding BSI-201 to a combination of the chemotherapy medicines Gemzar and carboplatin didn't cause any more side effects than the chemotherapy medicines alone. More research is needed to determine if a PARP inhibitor can effectively treat advanced-stage, triple-negative breast cancer.
Nexavar (chemical name: sorafenib): Cancer cells need a steady blood supply to grow and spread. To ensure this steady supply, cancers can make new blood vessels grow into the tumor. This new blood vessel growth is called angiogenesis. The targeted therapy medicine Avastin works by blocking angiogenesis and starving the cancer. Nexavar is a new targeted therapy that also blocks angiogenesis. Nexavar also blocks the actions of other proteins that tell cancers to grow and spread. Nexavar has been approved to treat advanced-stage liver and kidney cancers.
An early study gave Nexavar with and after the chemotherapy medicines doxorubicin, cyclophosphamide, and paclitaxel to lower the risk of breast cancer coming back (recurrence) in a small number of women. The women had been diagnosed with early-stage breast cancer that had spread to the lymph nodes or were considered at high risk for the cancer coming back. The researchers found Nexavar caused a small increase in side effects compared to the chemotherapy medicines alone. More research is needed to see if Nexavar and chemotherapy can reduce the risk of breast cancer coming back after surgery.
Research on new treatments and new uses for current medicines offers hope for more effective breast cancer treatment options. Still, much more research is needed before any of these new medicines are widely available.
If you're being treated for breast cancer, especially advanced-stage breast cancer, you and your doctor might consider whether participating in a clinical trial makes sense for you. Clinical trials are designed to answer very specific questions about the new treatment, so your unique situation will be carefully considered before you're accepted into a trial. Besides the benefits you might get from the treatment being studied, being in a clinical trial allows you to help find better breast cancer treatments.