The present invention relates to the HDM2-p53 interaction inhibitors (S)-5-(5-Chloro-1-methyl-2-oxo-1,2-dihydro-pyridin-3-yl)-6-(4-chloro-phenyl)-2-(2,4-dimethoxy-pyrimidin-5-yl)-1-isopropyl-5,6-dihydro-1H-pyrrolo[3,4-d]imidazol-4-one (HDM201), or a pharmaceutically acceptable non-covalent derivative theeof, for use in the treatment of patients with hematological tumors, wherein the drug is administered by an extended low dose dosing regimen.本發明係關於HDM2-p53交互作用抑制劑(S)-5-(5-氯-1-甲基-2-側氧基-1,2-二氫-吡啶-3-基)-6-(4-氯-苯基)-2-(2,4-二甲氧基-嘧啶-5-基)-1-異丙基-5,6-二氫-1H-吡咯并[3,4-d]咪唑-4-酮(HDM201),或其醫藥學上可接受之非共價衍生物,其係用於治療患有血液腫瘤之患者,其中該藥物係藉由長期低劑量給藥方案投與。