Successful treatment of relapsed AML after allogeneic stem cell transplantation with azacitidine.

Therapeutic options for patients with relapse of MDS or high risk AML after allogeneic stem cell transplantation are limited. We here present the case of a 64-year-old female patient with MDS, who received peripheral blood stem cells from her HLA-identical brother after a non-myeloablative conditioning regimen. Two months after allogeneic transplantation she suffered from a relapse, now fulfilling WHO criteria for AML with a bone marrow blast count of 91%. We then decided to treat her with azacitidine, a DNA methyltransferase inhibitor with proven antileukemic activity. The patient achieved a complete haematological response after two cycles and full donor chimerism after a single dose of donor lymphocytes. We postulate that azacitidine acts through a direct reduction of malignant cells and may in addition augment the immunologic effects of donor lymphocyte infusions.