CD33 and myelodysplastic syndrome: Azacitidine, the drug of choice in high-risk MDS, has been shown to affect T-cell polarization in the Th17/Treg-axis in high-risk MDS and to influence levels of BM CD57+ T-cells, CD57+ T-cell degranulation and CD34+ BM cell directed cytotoxicity.34,35 Specific MDSC-targeting in MDS has so far been aiming at CD33-expressing cells.36 So far, BI 836858 (Fc-engineered anti-CD33 moAb) for antibody-dependent cell-mediated cytotoxicity by NK-cells is currently tested in MDS patients in an ongoing Phase I/II clinical trial (ClinicalTrials.gov Identifier: NCT02240706).