The combination of the immune stimulating agent Tecentriq™ (atezolizumab), plus the chemotherapy agent Abraxane® (nab-paclitaxel) is effective in providing anti-cancer responses among patients with advanced triple-negative breast cancer (TNBC). These results were recently reported at the 2016 annual meeting of the American Society of Clinical Oncology (ASCO).
Approximately 10-20% of breast cancers are referred to as triple-negative breast cancer. These types of cancers are both hormone-negative and HER2-negative.
Hormone-negative breast cancer refers to a type of breast cancer that is both estrogen- and progesterone-receptor negative. This means that this type of cancer is not stimulated to grow from exposure to the female hormones estrogen and/or progesterone. Only about one-third or fewer breast cancers are hormone-negative.
Approximately 25-30% of breast cancers are referred to as human epidermal growth factor receptor (HER)2-positive, in which the cancer cells have a gene mutation that causes extra HER2 receptors to be present on the cell surface. Since the HER2 pathway is involved in cellular growth and replication, excessive HER2 receptors result in uncontrolled replication and spread of the HER2-positive cancer cells. HER2-negative breast cancer refers to cancer that does not have a mutated HER2 pathway, and therefore, is not stimulated to replicate and spread through the activity of excessive HER2 receptors.
Many treatments are available specifically for hormone-positive breast cancers, as well as HER2-breast cancers. Since these treatments are ineffective in TNBC, research efforts are underway to find new treatment options or optimal combinations of agents for this type of breast cancer.
Standard treatment for TNBC typically consists of surgery, chemotherapy, and/or radiation therapy. However, optimal chemotherapy regimens for TNBC continue to be explored.
Tecentriq is an agent that stimulates the immune system to recognize and mount an immune attack against cancer cells. It has already been approved for the treatment of bladder cancer and has demonstrated anti-cancer activity in metastatic TNBC in prior studies.
Researchers recently conducted a clinical trial to further evaluate the potential effectiveness of Tecentriq in the treatment of metastatic TNBC. The trial included 32 patients with advanced TNBC who were treated with Tecentriq plus Abraxane. Patients had received a median of 5 prior systemic therapies. Interim analysis of the data were presented at the 2016 annual ASCO meeting:
- Overall anti-cancer responses were achieved in 38% of patients. Among the patients who had not received prior therapy, 46% achieved an anti-cancer response.
- A complete disappearance of cancer was achieved in 3% of patients; a partial reduction in cancer was achieved in 34%; and disease stabilization was achieved in 44% of patients.
- The most common serious side effects were low levels of blood cells and diarrhea.
The researchers concluded that the treatment combination consisting of Tecentriq plus Abraxane provides significant anti-cancer activity among patients with advanced TNBC, even among those who have received extensive prior therapies. Based upon these results, Tecentriq plus Abraxane is now being evaluated in a phase III clinical trial for advanced TNBC.
Reference: Adams, S, et al. Phase Ib trial of atezolizumab in combination with nab-paclitaxel in patients with metastatic triple-negative breast cancer (mTNBC). Proceedings from the 2016 annual ASCO meeting. Abstract #1009. Available at: https://meetinglibrary.asco.org/content/169304-176. Accessed June 17, 2016.
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