Factors affecting blood stem cell collections following high-dose cyclophosphamide mobilization in lymphoma, myeloma and solid tumors

Abstract

Sixty patients with malignancy were enrolled in a study of high dose chemotherapy and peripheral blood stem cell transplantation (PBSCT). The International Journal of Cell Cloning were harvested prior to PBSCT using 75 cycles of high-dose Cyclophosphamide (Cy) mobilization (4 or 7 G/m2) with collection of a median of 4.6 × 108/kg mononuclear cells (MNC) (range 0.2 - 9.5) and 21.6 × 104/kg colony forming unit - granulocyte /macrophage (CFU-GM) (range 0.1 -220). Forty seven patients were mobilized once, 11 required 2 cycles and 2 required 3 cycles. Eight patients (13%) failed to reach the optimim CFU-GM target (total of > 15 × 104 CFU-GM/kg) following Cy mobilization. In a multivariate regression analysis, a number of factors identified those patients who were likely to achieve optimum stem cell collections. These included the use of the higher Cy mobilization dose (P <0.02), a longer interval from last chemotherapy cycle to mobilization(P <0.01) and a higher pre-mobilization bone marrow CFU-GM level (P <0.005). Patient's age, the degree of bone marrow infiltration, the kind of disease or the number of premobillzation chemotherapeutic cycles did not affect the ability to collect adequate stem cell numbers. The mobilization procedure was associated with moderate non-hematologic toxicity and significant hematological morbidity was observed primarily in patients mobilized using the 7 G/m2 dose. Patients mobilized at the higher Cy dose experienced significantly prolonged median days with ANC < 500 (10 vs. 6.6) and platelets < 50,000 (7 vs. 1.4), deeper neutropenic and thrombocytopenic nadirs, more febrile days and bacteremic episodes (P for all < 0.0001). Refinements to the protocol, in particular the use of hematopoietic colony-stimulating growth factors, are currently under investigation.