According to results recently presented at the 2004 San Antonio Breast Cancer Symposium, the newly approved chemotherapy agent Abraxane™ (nanoparticle paclitaxel) produces anti-cancer responses in women with breast cancer that no longer responds to the class of chemotherapy agents referred to as taxanes.
Breast cancer is diagnosed in approximately 250,000 women annually in the United States alone. Although breast cancer often responds to initial therapy, it may recur, particularly if the cancer has spread from the site of origin and is considered to be advanced. Once the cancer stops responding to a chemotherapy agent, it is referred to as refractory to that class of agents. The taxanes (Taxotere®, paclitaxel) are commonly used chemotherapy agents in the treatment of breast cancer. Although patients with taxane-refractory breast cancer have further chemotherapy options available to them, researchers are comparing the effectiveness of different agents for this group of patients.
Abraxane™ is a chemotherapy agent that includes the active ingredient of paclitaxel. However, the ingredients in paclitaxel also include agents that allow for the proper storage and administration of the drug. These agents in paclitaxel are responsible for the development of many side effects associated with treatment of the drug. 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. Abraxane™ was recently approved for the treatment of patients with breast cancer that have received prior treatment with anthracyclines (doxorubicin, epirubicin, Doxil®), but has recurred following treatment.
Researchers from U.S. Oncology recently conducted a clinical trial to evaluate the effectiveness of Abraxane™ in the treatment of taxane-refractory breast cancers. This trial included 75 patients with advanced breast cancer who were refractory to taxanes. Patients had received an average of approximately 3 prior chemotherapy regimens. Overall anti-cancer responses were achieved in over 50% of patients, with the reduction of cancer size in 12% of patients, and cancer stabilization in terms of progression occurring in approximately 40% of patients. Severe low levels of white blood cells (neutropenia) occurred in only 3% of patients, and severe loss of sensation in hands or feet (sensory neuropathy) occurred in 17% of patients. Of the patients who suffered from severe sensory neuropathy, 77% were able to be re-treated with Abraxane™ at lower dose levels. Seventy-five percent of all patients in the trial were able to receive continued full doses of Abraxane™.
The researchers concluded that Abraxane™ produces significant responses in patients with taxane-refractory breast cancer. Although the active ingredient of Abraxane™ is that of the taxane paclitaxel, significant benefit was derived from its use. Patients with taxane-refractory breast cancer may wish to speak with their physician regarding the risks and benefits of treatment with Abraxane™.
Reference: O’Shaughnessy JA, Blum JL, Sandbach JF, Savin MA, Fenske E, Hawkins MJ, Baylor-Charles A: Weekly nanoparticle albumin paclitaxel (Abraxane) results in long-term disease control in patients with taxane-refractory metastatic breast cancer [abstract 1070] San Antonio Breast Cancer Symposium, San Antonio, TX, Dec 8, 2004.