Incorporating the use of GM-CSF in the treatment of chronic lymphocytic leukemia

We evaluated the clinical activity of GM-CSF in combination with standard dose rituximab in patients with chronic lymphocytic leukemia (CLL). The rationale for exploring this combination is provided by the ability of GM-CSF to increase surface expression of CD20 in CLL cells and potentially render them a better target for rituximab. GM-CSF also enhances antibody-dependent cellular cytotoxicity against CLL cells. The combination of GM-CSF and rituximab was evaluated as initial treatment in elderly patients with indication for treatment and in patients at high risk for progression identified by elevated β² microglobulin. This combination was also evaluated in patients with recurrent CLL. On the basis of the results of 118 patients, we observed an overall response rate of 65 and 9% complete remission and these results compare favourably with the results obtained with rituximab single agent. This combination was well tolerated with the most common toxicity consisting in mild GM-CSF injection site erythema. On the basis of this experience, we are currently evaluating the use of GM-CSF in combination with the chemoimmunotherapy regimen fludarabine, cyclophosphamide and rituximab.