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 beta(2) 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.