azacitidine + valproic acid + hydroxyurea + donor leukocyte infusions

This is a combination therapy involving four components used primarily in the treatment of acute myeloid leukemia (AML), especially in post-transplant relapse settings. The combination includes: - **Azacitidine**: A hypomethylating agent that incorporates into DNA and RNA, leading to DNA hypomethylation and reactivation of tumor suppressor genes, thereby inhibiting cancer cell proliferation. - **Valproic acid**: A histone deacetylase (HDAC) inhibitor that modulates gene expression epigenetically, with immunosuppressive effects on immunocompetent cells; it may stabilize clinical status and improve quality of life in AML patients. - **Hydroxyurea**: An antimetabolite that inhibits ribonucleotide reductase, blocking DNA synthesis by stopping cells from making DNA; it slows or stops growth of cancer cells and is used for various hematologic malignancies. - **Donor leukocyte infusions (DLI)**: Immunotherapy involving infusion of donor immune cells after allogeneic stem cell transplantation to enhance graft-versus-leukemia effect. The combination aims to provide low-toxicity outpatient treatment for unfit or elderly AML patients with posttransplant relapse. Valproic acid combined with azacitidine/hydroxyurea has shown feasibility without inducing graft-versus-host disease (GVHD) progression in most cases. Hydroxyurea synergizes with valproic acid by amplifying S-phase arrest and increasing DNA damage in AML cells. Donor leukocyte infusions add an immunotherapeutic component enhancing anti-leukemic effects.