The investigative agent, atezolizumb, in addition to the chemotherapy agent, Abraxane (nab-paclitaxel), provides high anti-cancer responses among patients with triple-negative breast cancer. These results were recently presented at the 2015 annual San Antonio Breast Cancer Symposium.

Approximately 10-20% of breast cancers are referred to as triple-negative breast cancer (TNBC). 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.

Researchers recently conducted a clinical trial to explore the effectiveness of a treatment combination consisting of an investigational agent, azetolizumab, and Abraxane.

Azetolizumab is an agent referred to as a checkpoint inhibitor. It helps the immune system recognize cancer cells as a threat, so that an immune attack is initiated against the cancer.

The recent trial included women with advanced TNBC.

• Anti-cancer responses with atezolizumab/Abraxane were achieved 70.8% of patients.
• Among patients who had not received prior therapy for advanced TNBC, anti-cancer responses with atezolizumab/Abraxane were achieved in nearly 89% of patients.
• Serious side effects were not increased with the addition of atezolizumab to Abraxane, when compared to prior results of patients treated with Abraxane alone.

The researchers concluded that the treatment combination consisting of atezolizumab plus Abraxane provides high anti-cancer responses among women with advanced TNBC. Due to these promising results, a phase III clinical trial further evaluating this treatment combination has been initiated.

Reference: Adams S, et al. Safety and clinical activity of atezolizumab (anti-PD-L1) in combination with nab-paclitaxel in patients with triple-negative breast cancer. Proceedings from the 2015 annual San Antonio Breast Cancer Symposium. Presented December 10, 2015. Abstract number: 850477.

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