Cell-Freezing Devices Are Not Strictly Needed to Start an Autologous Hematopoietic Transplantation Program: Non-Cryopreserved Peripheral Blood Stem Cells Can be Used to Restore Hematopoiesis after High Dose Chemotherapy: A Multicenter Experience in 268 Autografts in Patients with Multiple Myeloma or Lymphoma. Study on Behalf of the Latin-American Bone Marrow Transplantation Group (LABMT)

Storage of peripheral blood stem cells (PBSC) at 4ºC is a simple and inexpensive alternative to cryopreservation for preserving the clonogenic capacity of progenitors cells in the autologous transplant setting, however it has been perceived as unsafe and has deserved little attention. We present the experience of two Latin-American centers using refrigerated, non-cryopreserved stem cells after conditioning with high dose melphalan, CBV or BEAM in a large group of lymphoma and myeloma patients

Materials and Methods

PBSC were mobilized with filgrastim 5 mg/kg/BID for three to six days.One to three apheresis procedure were employed; the cells were stored at 4ºC for 5 to 6 days in patients who received BEAM or CBV and for 3 days in those given melphalan. All of the conditioning regimens were administered preserving the full intensity of dose (Table 1). After the autograft all patients received filgrastim or pegfilgrastim

Results

102 lymphoma patients: 48 Hodgkin`s lymphoma (HL) and 54 non-Hodgkin´s lymphoma (NHL) received BEAM (71) or CBV (31). A median of 3.3 millions/kg of CD34 was infused; the median viability of the cells after 5-6 days of refrigeration (trypan blue exclusion) was 82%. 101 out of 102 patients engrafted, median time to achieve 500/ul neutrophil or more was 12 days, 100 were evaluable for thrombopoiesis, 99 of them had a self- sustained platelet count of 20.000 or more at a median of 17 days. The OS at 5 years was 59% and 42% for patients with Hodgkin and lymphoma respectively

151 patients with multiple myeloma received melphalan 200 mgs/m2. After 72 hours of refrigeration, a median of 2.6 millions/kg of CD34 cells were infused, the viability in all cases being > 90%. Three patients were not evaluable because early death. Median time to achieve 500 neutrophil or more and 20.000 platelets was 12 (9-50) and 15 (7-50) days. The OS at 5 years was 50%

21 patients with NHL and HL received as conditioning regimen melphalan 200 mgs/m2. After 72 hours of storage, a median of 1.75 millions/kg of CD34 cells were transplanted, 100% of them engrafted, median time to 500 neutrophils and 20.000 platelets was 11.9 and 15 days respectively

There were no cases of secondary engraftment failure in any of the three groups

Conclusion

In this series of 268 patients, we have shown that autologous PBSC can be kept at 4ºC in a conventional blood bank refrigerator for up to six days and use them to rescue high-dose chemotherapy in both multiple myeloma and lymphoma patients.

Avoiding freezing procedures results in substantial cost savings. The availability of freezing devices for hematopoietic stem cells is not anymore an obstacle to start a an autologous transplantation program This observation is critical in areas of underprivileged economic circumstances, where more than 50% of the inhabitants of the world live.