Peripheral blood stem cell (PBSC) mobilization and transplantation after fludarabine therapy in chronic lymphocytic leukaemia (CLL): a report of the European Blood and Marrow Transplantation (EBMT) CLL subcommittee on behalfof the EBMT Chronic Leukaemias Working Party (CLWP)

We performed a survey from 122 centres of the European Group of Blood and M arrow Transplantation (EBMT) concerning peripheral blood stem cell (PBSC) m obilization after fludarabine treatment of patients with chronic lymphocyti c leukaemia (CLL). A total of 101 leucaphereses from 29 patients was perfor med. The median cell numbers collected were: CD34+ cells, 2.2 x 10(6)/kg (0 .1-15.3); granulocyte-macrophage colony-forming units (GM-CFU), 4.29 x 10(4 )/kg (0.4-177); and mononuclear cells, 6.4 x 10(8)/kg (1.3-63). In univaria te and multivariate analyses, the numbers of cells collected were not signi ficantly influenced by the nature of mobilizing regimen and there was a tre nd towards the collection of a higher number of CD34+ cells from patients w ho received fludarabine only before mobilization. There was a significant c orrelation between the median number of CD34+ cells collected and the numbe r of courses of fludarabine (higher CD34+ cell numbers were related to more than six courses) and the interval between the last dose of fludarabine an d the start of mobilizing therapy (higher CD34+ cell numbers were related t o a delay greater than or equal to 2 months). Sixteen patients have subsequ ently undergone autologous transplantation and showed rapid engraftment. In conclusion, the results reported favour early stem cell mobilization in CL L patients who are in remission after first-line therapy. However, attentio n should be given to the timing of mobilization with respect to the time si nce the last dose of fludarabine.