[Ex vivo and in vivo purging for PBSCT]

Relapse due to either residual host disease or reinfused tumor cells remains the principal cause of treatment failure after autologous stem cell transplantation. It is very attractive to remove contaminated tumor cells from autologous grafts prior to transplant and many purging techniques including hyperthermia we developed, have been reported on this subject. However, there are only limited data suggesting that purging autografts have any favorable effect on relapses or disease-free survival. Drug-treated purging and CD34 positive cell selections that remove substantial numbers of T cells or destroy stem cells may have adverse effects such as delayed hematopoietic or T cell recovery. Therefore, there is a critical need for large, well-designed trials to re-evaluate ex vivo and in vivo purging effects on relapses and disease-free survival after autologous stem cell transplantation.