Nanoparticle albumin-bound paclitaxel for treatment of metastatic breast cancer.

Two taxanes, paclitaxel and docetaxel, are among the most widely used chemotherapeutic agents in solid tumor oncology, with efficacy against tumors of the breast, lung, head and neck, ovary, prostate, stomach and urothelium. The taxanes have been studied extensively and have been proven effective for treating early and advanced breast cancer. However, paclitaxel and docetaxel are both highly hydrophobic compounds, requiring synthetic solvents for parenteral administration. The solvents in commercially available preparations cause life-threatening toxic effects and decreased efficacy, and they are inconvenient to administer. Nanoparticle albumin-bound paclitaxel (nabP) is a novel, solvent-free formulation of paclitaxel. With nabP, in contrast to standard paclitaxel, life-threatening hypersensitivity reactions have not been observed, and it can be administered safely without steroid and antihistamine premedication. Furthermore, nabP exploits cellular and tumor transport mechanisms to preferentially target tumor cells. Data from phase III studies of metastatic breast cancer demonstrated higher response rates, longer time to progression and an improved toxicity profile for nabP compared with standard paclitaxel. The U.S. Food and Drug Administration approved nabP in late 2004 for treatment of metastatic breast cancer after failure of an anthracycline-based regimen.