Chemopurging of peripheral blood-derived progenitor cells by alkyl-lysophospholipid and its effect on haematopoietic rescue after high-dose therapy.

One reason for relapse after high-dose tumor therapy with subsequent autologous stem cell transplantation is tumor cell contamination of the graft. Removal of tumor cells from bone marrow grafts by chemopurging with the ether lipid edelfosine has been established as an effective and simple method. When compared with bone marrow derived grafts, progenitor cells from peripheral blood have considerably reduced the haematological recovery times. However, this advantage is put at risk by the nonspecific haematotoxic activity of the purging agent. We therefore compared the in vitro recovery of peripheral blood derived progenitor cells (PBPC) from either non-purged (n = 41) or purged (75 micrograms/ml of ether lipid for 4 h at 37 degrees C, n = 48) leukapheresis products. The recovery of CFU-GM after cryopreservation was 63 +/- 4% without and 48 +/- 3% with purging (P = 0.007). After high-dose therapy, patients (n = 37) received similar amounts of either non-purged (n = 17) or purged (n = 20) autologous PBPC. The median haematological recovery times (non-purged vs purged) to > 500 WBC/microlitres were 9.0 vs 8.5 days after transplantation, to > 2000 PMN/microlitres 10.5 vs 10.0 days, and to > 50,000 PLT/microlitres 15.5 vs 14.0 days. All differences were statistically not significant. We conclude that ether lipid purging of PBPC leads to a significant, however tolerable loss of progenitor cells in vitro, and that haematological recovery times after high-dose therapy are identically short, provided similar amounts of PBPC are reinfused.