This pilot trial will determine whether retroviral-transduced peripheral blood progenitor cells (PBPCs) can be selected and expanded in vivo after non-ablative chemotherapy in patients with metastatic breast cancer. It will also examine the feasibility of administering induction high-dose therapy with antimetabolites, followed with consolidation using high-dose single alkylating agent therapy and finally intensification therapy with sequential cycles of very high doses of the natural product breast cancer chemotherapeutic agents (paclitaxel followed by doxorubicin).