A very small study found that BSI-201, an experimental targeted therapy medicine, makes chemotherapy work better against aggressive forms of breast cancer. These results confirm findings from earlier studies. These results were reported at the 2009 San Antonio Breast Cancer Symposium.
DNA carries genetic information in both healthy and cancer cells. Chemotherapy medicines work against cancer by damaging the DNA or blocking DNA reproduction. But all cells can fix DNA damage caused by chemotherapy medicines. So sometimes cancer cells may not respond or stop responding to a chemotherapy medicine. When cancer stops responding to a treatment, it's called "treatment resistance."
BSI-201 is a PARP inhibitor. The PARP (poly ADP-ribose polymerase) enzyme fixes DNA damage in cells, including DNA damage caused by chemotherapy medicines. Scientists developed PARP inhibitors based on the idea that a medicine that interferes with or inhibits the PARP enzyme might make it harder for cancer cells to fix damaged DNA, which would make it harder for cancer to become resistant to chemotherapy.
In this study, 123 women diagnosed with advanced-stage, triple-negative (HER2-negative, estrogen-receptor-negative, progesterone-receptor-negative) breast cancer were treated with a combination of two standard chemotherapy medicines: gemcitabine (brand name: Gemzar) and carboplatin (brand name: Paraplatin). Half of the women also received BSI-201. All of the women had received a variety of other cancer treatments before this study.
The women who got the two chemotherapy medicines plus BSI-201:
- were more likely to respond to treatment; 48% of the women who got BSI-201 had some response to treatment, compared to only 16% of women who didn't get BSI-201
- lived longer without the cancer getting worse; women who got BSI-201 lived for almost 7 months without the cancer getting worse, compared to about 3 months for women who didn't get BSI-201
- lived longer overall; women who got BSI-201 lived for about 12 months compared to about 8 months for women who didn't get BSI-201
Women who got BSI-201 plus chemotherapy had the same types and severity of side effects as the women who got only chemotherapy.
While this study is promising, BSI-201 is considered an experimental treatment. More research is needed before doctors completely understand how and when to use PARP inhibitors to treat breast cancer.
If you're being treated for advanced-stage breast cancer, you and your doctor may be considering a number of treatment options, especially if the cancer has stopped responding to standard treatments. If you're willing to participate in a clinical trial, you may have even more options available, possibly including a PARP inhibitor. Talk to your doctor about clinical trials that might be a good fit for you and your unique situation. Visit the Breastcancer.org Clinical Trials pages for more information.
Stay tuned to Breastcancer.org Research News to learn about the latest research on new, better ways to more effectively treat breast cancer.