On December 7, 2011, researchers speaking at the San Antonio Breast Cancer Symposium (SABCS) described findings from two studies that have promising results for women with advanced breast cancer. In a large international study, the experimental drug pertuzumab was found to delay breast cancer progression for a median of 18 months when it was administered along with standard treatment, versus 12 months for women who received only the standard treatment. Pertuzumab targets cells that produce excess HER2 protein. The study compared women who received docetaxel chemotherapy plus trastuzumab (Herceptin) to those who received these two agents plus pertuzumab. To date, 165 deaths have occurred; 96 of the 406 women given trastuzumab and docetaxel, and 69 of the 402 women who were also given pertuzumab. The researchers noted that it’s still too early to calculate survival rates. The most common side effects associated with pertuzumab were diarrhea, rash, and neutropenia.
In a second study, a drug that has been used in organ transplantation, everolimus was found to delay progression of breast cancer for a median of 7 months in women whose disease was worsening despite treatment with hormone-blocking drugs. A comparison group of women who received only hormonal agents had a 3-month delay in disease progression. The 724 women in the study had worsening disease despite treatment with hormone-blocking medicines. They all were given a hormonal agent they had not taken previously, and some also received everolimus. After a year of follow-up, cancer progression was delayed 7 months in the group receiving everolimus and 3 months for the other women in the study. The combination of hormonal therapy plus everolimus was associated with a greater number of side effects, including stomatitis, anemia, shortness of breath, fatigue, and elevated blood glucose levels.
It’s good news that there are new agents on the horizon for women with advanced breast cancer. The withdrawal of support for treatment with Avastin has left women with breast cancer with fewer treatment options, and these SABCS announcements should inspire hope among women with advanced breast cancer.