Nanoparticle albumin-bound paclitaxel in the treatment of metastatic breast cancer

This study examined the benefits of nanoparticle albumin-bound paclitaxel in combination with bevacizumab as first-line treatment (the first treatment of choice) for metastatic breast cancer patients.

Paclitaxel is one of several chemotherapy drugs used to treat cancer. However, treatment is often associated with severe side effects such as hypersensitivity (an allergic reaction to the drug), neutropenia (a dangerously low white blood cell count) and infections. In addition, not all patients respond to therapy.

Nanoparticle albumin-bound paclitaxel (nab-P or abraxane) is a new formula in which the drug (paclitaxel) is bound to small albumin particles. These particles prevent the drug from dissolving into the blood stream and help to concentrate it within the tumor. Nab-P has been shown to have several advantages, such as fewer side effects, shorter treatment times and overall better response rates. Currently nab-P is only used in the treatment of breast cancer patients as second-line therapy (in patients that have progressed or relapsed despite previous treatments). The use of nab-P as first line therapy is currently under investigation.

Bevacizumab (avastin) is a drug that prevents the formation of new blood vessels needed for the growth and spread of tumors.

This study included 208 women diagnosed with metastatic breast cancer. Patients were assigned to receive nab-P in different doses and at different schedules to assess the most beneficial method of treatment. Group A was treated with high dose nab-P every 3 weeks, Group B was treated with high dose nab-P every 2 weeks, and Group C was treated with low dose nab-P every week.

On average, 45% of patients responded to treatment. The average progression free survival (PFS; the between treatment and until the disease progresses or worsens) was 7.7 months for group A patients, 5.8 months for group B patients, and 8.8 months for group C patients. Overall survival was 21.3 months for group A patients, 19 months for group B patients, and 23.7 months for group C patients.

However, several side effects were also related to treatment. These included bone pain, fatigue, and nerve damage. Administration of nab-P every two weeks was stopped before the end of the trial due to high toxicity.

In conclusion, nab-P showed significant anti-tumor activity when used as first-line therapy for metastatic breast cancer patients. However, several side effects were also reported. Weekly small dose treatments were found to be related to the least amount of adverse effects.

This study was an early phase trial aimed at optimizing treatment doses and timing for future trials. Large trials directly comparing the effects of nab-P to standard treatments are needed to reach conclusive results. In addition, since the beginning of this trial the FDA has recommended that bevacizumab no longer be used in the treatment of breast cancer patients. This study was supported by Abraxis Bioscience, the manufacturers of nab-P (abraxane).

Consult with your physician regarding the various chemotherapy agents available for the treatment of metastatic breast cancer.