NEW STRATEGIES IN MARROW PURGING FOR BREAST-CANCER PATIENTS RECEIVINGHIGH-DOSE CHEMOTHERAPY WITH AUTOLOGOUS BONE-MARROW TRANSPLANTATION

High-dose chemotherapy and autologous bone marrow transplantation (ABM T) are commonly used to treat selected patients with high-risk breast cancer. A limitation of ABMT is that clonogenic cancer cells could be collected with the bone marrow and produce a relapse of disease when r einfused into patients. Purging the marrow ex vivo may eliminate the t umor cells, but it can also delay engraftment. We employed two differe nt purging methods whereby breast cancer cells were depleted without d elaying engraftment. The addition of WR-2721 (amifostine) to 4-hydrope roxycyclophosphamide (4-HC) reduced the time to engraftment by 10 days compared with marrow purged with 4-HC alone (26 versus 37 days, respe ctively). The positive selection of CD34+ hematopoietic progenitors pr oduced engraftment within 21 days. The use of granulocyte colony-stimu lating factor (G-CSF) accelerated the engraftment time of CD34+ hemato poietic progenitors to 11 days.