Patients mobilizing large numbers of CD34+ cells ('super mobilizers') have improved survival in autologous stem cell transplantation for lymphoid malignancies

The cellular composition of an autologous graft may influence autologous stem cell transplantation (ASCT) outcome. Etoposide (VP) plus filgrastim (G) frequently mobilizes high numbers of CD34+ cells for autologous transplantation. We investigated whether patients collecting high numbers of CD34+ cells ('super mobilizers') have a better outcome than other patients. We reviewed 350 consecutive adult patients with NHL or Hodgkin's lymphoma receiving an ASCT from January 1994 to December 2005, mobilized with VP+G. Super mobilizers were defined as collecting a minimum of 8 × 10⁶ CD3+ cells/kg. Two hundred and three patients were super mobilizers, while 147 collected between 2.0 and 7.95 CD3+ cells/kg. Super mobilizers were younger and more likely to have received two or fewer prior chemotherapy regimens (80 versus 63%, P>0.001). Median CD34+ cell dose for the super mobilizing group was 13.7 × 10⁶ versus 4.4 × 10⁶/kg in the standard collecting group. The super mobilizer group had a superior overall survival (P=0.006). In multivariable analysis, favorable disease status and younger age at transplant, and super mobilization were associated with improved survival. We conclude that patients had an improved ASCT outcome if large numbers of CD34+ cells were mobilized and infused. The explanation for this observation is unknown.