Importance of blood graft characteristics in auto-SCT: implications for optimizing mobilization regimens.

Although blood stem cells have been widely used to support high-dose therapy in the autologous setting, limited data are available on the effects of graft characteristics in patient outcomes other than haematopoietic engraftment. Retrospective studies suggest that patients who mobilize more CD34(+) cells have better outcomes than do patients who mobilize less well. Furthermore, immunological reconstitution may be important in terms of post-transplant outcome and is apparently affected by graft composition. There is accumulating evidence that the mobilization regimen used may be an important determinant of graft content. Plerixafor has been recently introduced combined with G-CSF in patients who mobilize poorly. In addition to enhancing mobilization of CD34(+) cells, there are indications that plerixafor may also affect other graft components. A combination of chemotherapy plus G-CSF with plerixafor has been shown to be very effective in stem-cell mobilization, but more data are needed in regard to other graft characteristics in this setting. Prospective studies are needed to evaluate whether higher CD34(+) doses or other modifications to graft composition translate into better long-term outcomes in the autologous setting. These studies are not only important in regard to defining the optimal stem-cell graft in the autologous setting, but also in identifying the optimal mobilization regimen.