Simultaneous administration of G-CSF and GM-CSF for re-mobilization in patients with inadequate initial progenitol cell collections for autologous transplantation

Background A proportion of candidates for high-dose chemotherapy with autologous PBPC support (HDC-PBCS) will not provide an adequate PBPC yield from their first mobilization. The value of re-mobilization. The value of re-mobilization a nd the best regimen for re-mobilization in these patients is unclear. Methods In 23 patients who failed to provide greater than or equal to 3 X 10(6) CD3 4(+) cells/kg after their first mobilization, PBPC were re-mobilized using a regimen of simultaneous administration of G-CSF and GM-CSF (10 mu g/kg/da y each) with leukaphereses (LP) starting Day 4 or 5 of CSF administration. Yields of WBC/kg, MNC/kg and CD34(+) cells/kg/L of processed blood were com pared between the first and second mobilization in each patient. The abilit y of the combined yield from the two mobilizations to achieve the desired t hreshold PBPC yield and the tolerability of the re-mobilization were determ ined. Results The re-mobilization regimen was well-tolerated and no patient discontinued the regimen because of toxicity. Median collected WBC/kg/L (1.37 X 10(7) ve rsus 2.62 X 10(7), p = 0.0065), MNC/kg/L (0.77 X 10(7) versus 1.97 X 10(7), p = 0.0003), CD34(+) cells/kg/L (1.64 X 10(7) versus 1.97 X 10(7),p = 0.00 1) were significantly higher after the second mobilization (G-CSF/GM-CSF co mbination). Percentage of CD34(+) cells in the leukapheresis was also signi ficantly higher after the second mobilization (median 0.104% versus 0.195%, p = 0.036). Twelve of 22 patients achieved the target PBPC dose (> 3 X 10( 6) /CD34(+)cells/kg) after two mobilizations (six patients achieved the tar get from the second mobilization alone). A further eight underwent HDC-PBPC S without achieving the target PBPC dose. These patients experienced a sign ificant delay in neutrophil and platelet engraftment when compared with tho se patients achieving the target dose. Discussion This study demonstrates that the combination of G-CSF and GM-CSF is an effe ctive and tolerable method for re-mobilization of PBPC in patients who fail to provide an adequate yield from their first mobilization.