Phase II Study of Ixabepilone in Metastatic Breast Cancer and Its Effects on the Ultrastructure of Neurons

Primary Objectives * Assess ultrastructure changes in dermal myelinated nerves of patients who receive ixabepilone chemotherapy * Detailed characterization of peripheral neuropathy in patients who receive ixabepilone Secondary Objectives * Clinical benefit rate * Time to progression ( TTP) * Toxicity * Exploratory studies: * Relation of MDR 1 and TRKA polymorphisms to evolution of ultrastructural neurologic changes observed in neurons. * Relation of NGF, IL8, and IL10 to the development of clinical symptoms and ultrastructural changes in neurons.

Eligible patient population: * Stage 4 breast cancer * Resolution from toxicity of prior therapy to ≤ CTC grade 1 ( except alopecia) * No limit on prior number of therapies to treat cancer * Adequate organ function * Life expectancy greater than 3 months Treatment: ixabepilone 40 mg/m2 Q3w over 3 hours Evaluation on Study: I. Efficacy evaluation: * Baseline CT chest, abdomen and pelvis and bone scan within 4 weeks of starting therapy * Evaluation of disease every 2 cycles of chemotherapy * Ongoing toxicity evaluation using NCI CTC 3. II. Neurological evaluation: * Detailed neurologic exam using Neuropathy Assessment Instrument (represents a standard neurological exam) * Serum NGF, IL 8,10, prior to starting therapy and prior to each cycle of ixabepilone * DNA for assessment of TRK A and MDR1 polymorphisms * Punch biopsy of skin prior to starting therapy and after every 2 cycles. Laboratory evaluation of peripheral nerve biopsies will be conducted at Rockefeller University under the direction of Dr. Carlson in Dr. Strickland's Lab.