Study of ABI-007 and Taxol in Patients With Metastatic Breast Cancer

Taxol (Bristol-Meyers Squibb) is active against carcinomas of the ovary, breast, lung, esophagus and head and neck. A number of dose schedules of Taxol have been tested in breast cancer. Initial trials used 250 mg/m2 as a continuous infusion over 24 hours. Subsequently, shorter infusions of Taxol over three hours were tested at a dose of 175 mg/m2, with response rates of 30%-40%. Phase II studies using higher doses of Taxol at 200-250 mg/m2 had a response rate of 56% in metastatic breast cancer patients. However, at these doses, significant toxicities occurred, including neuropathy. There was a median granulocyte count nadir at 100-200 cells/mm3 for the majority of courses administered. There were also significant side effects associated with hypersensitivity to the Taxol vehicle, Cremophor-EL. These hypersensitivity reactions require a premedication schedule that includes a corticosteroid, an H2 antagonist and an antihistamine. Abraxis BioScience is testing a reformulated form of paclitaxel without Cremophor. This formulation is a protein-stabilized, nanoparticle suspension of paclitaxel and human serum albumin in normal saline. The potential advantages of this formulation are: * Higher tolerated doses, with greater efficacy * Longer drug persistence in tumor as a result of the nanoparticle formulation * Reduced infusion time * Reduced risk of hypersensitivity with no required premedication schedule * More rapid distribution of paclitaxel to the tissues based on pharmacokinetic data This study will evaluate ABI-007, as compared to Taxol, in patients with metastatic breast cancer.