BREAST-CANCER CELLS ARE EFFECTIVELY PURGED FROM PERIPHERAL-BLOOD PROGENITOR CELLS WITH AN IMMUNOMAGNETIC TECHNIQUE

Peripheral blood progenitor cells (PBPCs) are being used increasingly to provide hematopoietic support after intensive chemotherapy, However , many investigators have detected tumor cells contaminating PBPC coll ections, Methods that eliminate the tumor cells and spare the normal h ematopoietic progenitor cells may improve the number of long-term, dis ease-free survivors after intensive chemotherapy, We developed an effe ctive method using anti-breast cancer murine monoclonal antibodies (Mo Abs) and immunomagnetic beads to eliminate a low percentage of breast cancer cells from PBPCs, We identified optimal anti-breast cancer MoAb s that react with membrane glycoproteins and conditions for selective removal of tumor cells, Using three anti-breast cancer MoAbs (260F9, 3 17G5, and 520C9) at 0.8 mu g/ml, a cell concentration of 2 x 10(8) cel ls/ml and a bead: total cell ratio of 0.75 beads:1 cell, we eliminated 3.3-4.8 (mean, 4.1) logs of tumor cells consistently from a model sys tem with 1% breast cancer cells and 99% normal PBPCs, Similar levels o f tumor cell elimination were obtained with three breast cancer cell l ines, Colony-forming units were not affected adversely, with a mean re covery of 200% compared with the control, A clinical trial has begun t hat uses immunomagnetically purged, autologous bone marrow and PBPCs t o support patients with metastatic breast cancer receiving high-dose c hemotherapy.