Several strategies have been tested in order to improve these results. The anti-CD20 monoclonal antibody rituximab, given concomitantly with allo-HCT or donor lymphocyte infusions, may reduce graft-versus-host disease and facilitate disease control. This may be due, not only to direct cytotoxicity, but also to modulation of GVHD and the graft-versus CLL effect (GVCLL). Interestingly, rituximab has been shown to promote the cross-presentation of tumor-derived peptides by antigen-presenting cells, thus enhancing the formation of cytotoxic T-cell clones and a GVCLL effect. With the addition of rituximab to the conditioning regimen, rates at 4 years for current progression-free survival (CPFS) and overall survival were 44% and 48%.