VIABILITY AND QUANTIFICATION OF PROGENITOR CELLS IN VENESECTED BLOOD FROM PATIENTS RECEIVING ESCALATED-DOSE EPIRUBICIN AND CYCLOPHOSPHAMIDEWITH G-CSF FOR LYMPHOMA - POTENTIAL ROLE IN FURTHER INCREASING DOSE-INTENSITY

We assessed the concentration of haemopoietic progenitors in periphera l blood in six patients with de novo intermediate grade non-Hodgkin's lymphoma receiving multiple cycles of escalated dose epirubicin and cy clophosphamide on day 1 followed by 5ug/kg of G-CSF (filgrastim) on da ys 2-14. Specimens were taken at days 12, 15 and 18 in cycles 1 and 2 and on day 15 for cycles 3-6. Progenitor numbers were maximal on day 1 5 in cycles 1 and 2. The median number of granulocyte-macrophage colon y forming cells (GM-CFC) and CD34(+) cells on day 15 of cycles 1 and 2 was 3.8 x 10(4)/ml and 11 x 10(4)/ml, respectively. A 600ml venesecti on at this time would contain a median of 36 x 10(4) GM-CFC/kg (range 25-47) and 1.04 x 10(6) CD34(+) cells/kg (range 0.73-1.4), based on in dividual patient weights. Day 15 progenitor numbers were maintained fo r the first 3 cycles but tended to fall thereafter. The viability of t he progenitors collected in whole blood and stored at 4 degrees C for various time intervals was also assessed. The median percent of GM-CFC and erythroid blast forming units (BFU-e) surviving after storage for 48hrs was 79% and 69% respectively and after 72hrs was 48% and 63% re spectively. Serum collected 2hrs after the completion of chemotherapy had minimal inhibitory effect on progenitors collected prior to treatm ent. Our data demonstrate that two weeks after anthracycline-based che motherapy and G-CSF in previously untreated patients the peripheral bl ood contains large numbers of progenitors. A 600ml venesection at this time stored at 4 degrees C, and then reinfused after the next cycle o f chemotherapy would contain sufficient viable progenitors to potentia lly hasten haematological recovery.