Autologous transplantation of blood stem cells mobilized with filgrastim alone in 93 patients with malignancies: the number of CD34+ cells reinfused is the only factor predicting both granulocyte and platelet recovery.

High-dose chemotherapy (HDC) supported by autologous transplantation of blood stem cells (BSC) is used increasingly for patients with poor-risk malignancies. We report our experience with 93 consecutive patients who were mobilized with recombinant human granulocyte colony-stimulating factor (rhG-CSF) alone. They received a fixed dose of G-CSF for 5 or 6 days, and BSC were collected by leukapheresis. Aphereses were evaluated for MNC, CD34+ cells, and CFU-GM counts and cryopreserved. All patients received a conditioning regimen without TBI. Engraftment was assessed as the first of 2 consecutive days on which patients achieved 0.5 and 1 x 10(9)/L neutrophils and an unsupported platelet count of 25 x 10(9)/L. Multivariate analysis was performed to study patients and graft characteristics that could influence reconstitution. The G-CSF priming regimen was well tolerated and allowed collection of BSC for all patients, 66% of them achieving >3 x 10(6)/kg CD34+ cells, and 86% achieving >10 x 10(4) CFU-GM/kg. The numbers of collected CD34 and CFU-GM cells were highly correlated. The number of courses of chemotherapy prior to collection, a diagnosis of breast cancer, the use of rhG-CSF posttransplant, and the numbers of CFU-GM and CD34+ cells reinfused were correlated with hematologic recovery. In a multivariate analysis, however, the number of CD34+ cells was the only factor independently influencing both granulocyte and platelet recovery. Patients who received at least 3 x 10(6)/kg CD34+ cells achieved granulocyte reconstitution on day 11 after reinfusion (range 8-15) and an unsupported platelet count of 25 x 10(9)/l on day 14 (range 12-180), significantly earlier than patients who received fewer cells (p < 0.001). In addition, G-CSF administration postreinfusion independently enhanced granulocyte reconstitution but not platelet recovery. In conclusion, CD34+ cell number appears to be the only factor predicting both granulocyte and platelet reconstitution. Based on this study, the collection of a minimal number of 3 x 10(6)/kg CD34+ cells appears desirable.