Preclinical studies comparing Abraxane to paclitaxel demonstrated lower toxicities, with a maximum tolerated dose (MTD) approximately 50% higher for Abraxane (7) compared to paclitaxel (11). At equal doses there was less myelosuppression and improved efficacy than paclitaxel in a xenograft tumor model of human mammary adenocarcinoma. Clinical studies confirmed improved toxicity profile and higher response rates, in metastatic breast cancer, of Abraxane compared to cremophor EL paclitaxel (Taxol) (5, 8). The weekly regimen was shown to be active even in patients with cancers refractory to paclitaxel, docetaxel or when Abraxane was given after both agents (8).