Albumin-Bound Paclitaxel in the Treatment of Metastatic Breast Cancer

The taxanes, paclitaxel and docetaxel, are an important class of antineoplastic agents with relevant clinical activity in both early and advanced breast cancer. Nanoparticle albumin-bound paclitaxel (Abraxane®) is a 130–nm particle cremophor-free formulation of paclitaxel. Exploiting endogenous albumin pathways and avoiding solvent-based toxicities, nab-paclitaxel allows higher intratumor concentrations of paclitaxel through gp60 mediated endothelial transcytosis. Also, because it is free solvents, nab-paclitaxel offers shorter infusions and easily administration with no premedication and special infusions sets. In a phase III randomized trial, nab-paclitaxel at 260 mg/m2 every 3 weeks seems to have a superior therapeutic index than Cr-El paclitaxel, with a higher response rate and longer time to progression and with less toxicity, except peripheral neuropathy. Based on these results, nab-paclitaxel was approved for the treatment of metastatic breast cancer in patients who have failed first-line treatment for metastatic disease and for whom standard; anthracycline containing therapy is not indicated. The results of the comparison of three doses of nab-paclitaxel with docetaxel in a randomized phase II trial suggest a superior efficacy and safety of weekly nab-paclitaxel compared with 3-weekly docetaxel. All the available data suggest the superior therapeutic index of nab-paclitaxel compared with both docetaxel and Cr-EL paclitaxel. Weekly nab-paclitaxel may be an adequate alternative to classic formulations of taxanes in the treatment of patients with metastatic breast cancer.