Immunomagnetic purging of breast cancer from bone marrow for autologous transplantation.

Intensive chemotherapy with autologous bone marrow transplantation is a promising approach for the treatment of breast cancer, provided that clonogenic tumor cells do not contaminate the patient's bone marrow. We have previously demonstrated that a combination of 4-hydroperoxycyclophosphamide (4-HC) and immunomagnetic purging (IMP) with monoclonal antibodies and microspheres could remove 4-5 logs of clonogenic breast cancer cells from a 10-fold excess of human bone marrow cells. In the present report we have evaluated an apparatus for separating tumor cells from a large volume of human marrow. This apparatus will permit preparation of large volumes of purged marrow for use in studies of intensive therapy with autologous marrow support. Bone marrow progenitor cell (CFU-GM) recovery following this IMP technique was 85% of the unpurged control, and suggests that marrow recovery following high dose systemic chemotherapy will not be adversely affected. A phase I study to evaluate marrow reconstitution following IMP is underway. Preliminary data suggest that this IMP method will not delay engraftment in breast cancer patients receiving high-dose chemotherapy and autologous bone marrow support, but further study is required.