- Phase I: Patients receive pentostatin IV on days -7, -5, and -3 followed by allogeneic stem cell transplantation on day 0. Beginning on day 1, patients receive filgrastim (G-CSF) IV over 1 hour or subcutaneously daily until blood counts recover. As graft-versus-host disease prophylaxis, patients receive cyclosporine IV continuously until stem cell engraftment and then orally with gradual tapering.