Target value tailored (TVT) apheresis approach for blood progenitor cell collection after high-dose chemotherapy and rh-G-CSF.

Twenty-eight patients with different hematological diseases (17 non-Hodgkin's lymphoma, one Hodgkin's disease and 10 multiple myeloma) underwent peripheral blood progenitor cell (PBPC) collection after cyclophosphamide 7 g/m 2 and rh-G-CSF. Fifty-eight leukaphereses were carried out with a fully automated PBPC collection procedure. Progenitor cell release was monitored by standardized determination of CD34 + cells in the peripheral blood. After a profound aplasia, a continuous increase in CD34 + cells in the peripheral blood was seen for at least 3-4 days. In 82% of our patients more than 2.5 x 10 6 CD34/kg could be collected using a standard apheresis of 10 1. There was a high correlation between the CD34 + cells in the peripheral blood and CD34 + cells/kg harvested. (r 2 = 0.91). A relatively constant ratio (median 14.3, range 3.2-22.6) was found between CD34 + cells/kg and CFU-GM/kg. Based on the CD34 values of the pre-apheresis blood and the body weight of an individual patient and using the mathematical model of regression analysis (y = mx + b) for the correlation between the CD34 + cells/μl in the pre-apheresis blood and the CD34 + cells/kg, it was possible to create a formula allowing for target value tailored apheresis. Using this formula, the blood volume which needs to be processed in order to harvest a desired number of CD34 + cells/kg can be calculated. This strategy can be applied to reduce the time for and the number of aphereses. Nineteen leukaphereses were carried out applying the formula. In 18 of 19 leukaphereses the expected CD34 + /kg values were correctly achieved or exceeded. The formula was most reliable when the CD34 value was higher than 15/μl and when the WBC count was below 20 x 10 9 /l in the pre-apheresis blood. For mobilizations using hematopoietic growth factors alone our formula is not applicable, because in most cases the pre-apheresis white blood cell count is higher than 20 x 10 9 /l and the collection efficacy of lymphomonocytoid cells decreases with a high pre-apheresis white blood cell count. The formula also works with other mobilization regimens that induce a pronounced aplasia.