The Food and Drug Administration (FDA) has recently approved the chemotherapy agent Abraxane™ (nanoparticle albumin paclitaxel) for the treatment of patients with breast cancer. The indication of Abraxane™ includes patients who have stopped responding to prior therapies that included a class of commonly used chemotherapy agents referred to as anthracyclines (doxorubicin, epirubicin, Doxil®).
Breast cancer is one of the most common cancers diagnosed in women. It is estimated that approximately 250,000 women are diagnosed annually in the United States and 40,000 deaths are attributed to breast cancer each year. Although treatment for patients with early-stage breast cancer, or cancer that has not spread from its site of origin, results in high cure rates, some patients ultimately experience a recurrence and spread of their cancer. Metastatic breast cancer refers to cancer that has spread from the breast to distant sites in the body, often invading vital organs. Survival for patients with metastatic breast cancer is poor, with the average survival time from diagnosis of this advanced stage of cancer being 18 to 30 months.
Treatment for metastatic breast cancer is aimed at improving the duration of survival and/or quality of life for patients, but often not with the intent to cure. Paclitaxel (Taxol®) is a chemotherapy agent that is commonly used in the treatment of breast cancer. Patients with cancer that has recurred following previous therapy and has developed into metastatic breast cancer are often treated with paclitaxel. The formulation of paclitaxel includes agents that allow for the proper storage and administration of the drug; however, these agents are also responsible for the development of many side effects associated with paclitaxel.
Abraxane™ is a new form of paclitaxel that is bound with albumin, which is a type of protein normally found in the human body. This form of paclitaxel delivers high concentrations of the active ingredient into the cancer cells and reduces the incidence of side effects, compared to the original form of the drug. The pivotal clinical trial that prompted FDA approval included a direct comparison of Abraxane™ to paclitaxel in patients with metastatic breast cancer. This trial included 460 patients, 14% of whom had not received prior treatment with chemotherapy and 77% of whom had received prior therapy that included an anthracycline. Anti-cancer response rates and time to cancer progression were improved in the group of patients treated with Abraxane™, compared to those treated with paclitaxel. Overall, anti-cancer response rates occurred in 33% of patients treated with Abraxane™, compared to only 19% of those treated with paclitaxel. Time to cancer progression was significantly longer in the group treated with Abraxane™ (nearly 22 weeks), compared to those treated with paclitaxel (approximately 16 weeks). In the subgroup of patients who had not received prior chemotherapy, anti-cancer responses were achieved in 42% of those treated with Abraxane™, compared to only 27% of those treated with paclitaxel. Severe neutropenia (low levels of immune cells) occurred in only 9% of patients treated with Abraxane™, compared to 22% of patients treated with paclitaxel. Sensory neuropathy (loss of sensation) occurred in 10% of patients treated with Abraxane™, compared with 2% of patients treated with paclitaxel. The neuropathy resolved itself in an average of 22 days in the group of patients treated with Abraxane™.
Patients with recurrent breast cancer may wish to speak with their physician about their individual risks and benefits of treatment including Abraxane™.
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