PERIPHERAL-BLOOD STEM-CELL TRANSPLANTS FOR MULTIPLE-MYELOMA - IDENTIFICATION OF FAVORABLE VARIABLES FOR RAPID ENGRAFTMENT IN 225 PATIENTS

Transfusion of autologous peripheral blood stem cells (PBSCs) of good quality ensures fast hematopoietic engraftment after myeloablative the rapy with a decrease in procedure-related morbidity and mortality. We have analyzed variables influencing the kinetics of engraftment, and t herefore reflecting the quality of PBSC collections, in 225 patients w ith newly diagnosed or refractory multiple myeloma (MM) who received a n autotransplant in support of high dose melphalan (200 mg/m(2)); 132 of these patients also completed a second transplant. All PBSCs were c ollected before the first transplant after high-dose cyclophosphamide (6 g/m(2)) and hematopoietic growth factors, mainly granulocyte-macrop hage colony-stimulating factor. PBSCs were administered either alone ( 91 patients) or with bone marrow (134 patients). A highly significant correlation was observed between the number of CD34(+) cells per kilog ram infused and prompt recovery of both granulocytes (P = .0001) and p latelets (P = .0001). After correction for the proportion of patients with greater than or equal to 2 x 10(6)/kg CD34 PBSCs infused and with less than or equal to 12 months of prior therapy, no difference in en graftment kinetics was seen between patients receiving PBSCs only and those also receiving bone marrow. Exposure to chemotherapy, even to le ss than or equal to 6 months of alkylating agents, significantly delay ed hematopoietic recovery posttransplantation. The threshold dose of C D34 cells necessary for prompt engraftment was greater than or equal t o 2.0 x 10(6)/kg for patients with less than or equal to 24 months of chemotherapy before the first transplant, whereas greater than 5 x 10( 6)/kg CD34 cells were required to assure rapid recovery also in those with longer exposure. Such quantities, easily collected in the large m ajority of patients with shorter exposure (91%), were obtained in only 28% of patients with more than 24 months of prior chemotherapy. Rapid platelet recovery within a narrow range of time (before day 14) was a lmost invariably seen (94%) when greater than 5 x 10(6)/kg CD34 cells were infused, irrespective of the duration of prior therapy, whereas t he range widened progressively when less CD34 cells were infused. In t he absence of CD34 measurements, fast recovery of platelets to greater than 50 x 10(9)/L within 14 days after high-dose cyclophosphamide and less than or equal to 12 months of prior chemotherapy were the best p redictors of early engraftment. Prudent use of stem cell-damaging agen ts, such as melphalan and nitrosoureas, is recommended in MM patients who might be candidates for autotransplantation. Alternatively, PBSCs should be collected early after diagnosis. (C) 1995 by The American So ciety of Hematology.