ENGRAFTMENT CHARACTERISTICS OF PERIPHERAL-BLOOD STEM-CELLS MOBILIZED WITH CYCLOPHOSPHAMIDE AND THE DELAYED ADDITION OF G-CSF

The optimal protocol for the mobilisation of PBSC remains unknown. We present data on 42 patients mobilised with cyclophosphamide (3 or 4 g/ m(2)) and the delayed addition of a standard 300 mu g dose of G-CSF (F ilgrastim) from day +5. The patients had received a median of 2 previo us chemotherapy regimes, 38% had received prior radiotherapy and 38/42 had active disease at the time of mobilisation. The protocol was well tolerated and 38 patients proceeded to transplantation. The median nu mber of CD34+ cells reinfused was 4.3 x 10(6)/kg (range 0.5-30) and CF U-GM 15.8 x 10(4)/kg (range 0-148). The total number of CD34+ cells ha rvested correlated with the total number of CFU-GM available for reinf usion (P = 0.008). Overall engraftment occurred with median days to ne utrophils >0.5 x 10(9)/l or platelets >20 x 10(9)/l of 14 and 13 days, respectively, Patients receiving more than 2.5 x 10(6)/kg CD34+ cells had even more rapid haemopoietic reconstitution with significant redu ctions in hospital stay and transfusion requirements. Those below this threshold had significantly delayed platelet engraftment. The mobilis ing dose of cyclophosphamide did not influence the achievement of the threshold CD34+ cell yield for optimal engraftment. The delayed additi on of a standard 300 mu g G-CSF dose after priming chemotherapy result ed in the use of a median 9 days hence 9 vials of G-CSF. This protocol presents the potential for cost saving without compromising the quali ty or success of PBSC mobilisation.