The isomer separation of the reaction product of the first stage is performed, and the composition of the high-purity compound SP-1 in which the HPLC purity of the single isomer SP-1 is 90% or more is obtained through two-step chemical synthesis. A method for producing a composition SP-1 rich composition to be produced. Compound SP-1 rich composition having significantly higher in vitro tumor cell growth inhibitory effect than NUC-1031 and Compound RP-1, use of this composition, and at least one pharmaceutically acceptable excipient with this composition A pharmaceutical composition comprising an agent. [Selection] Figure 7第１段階の反応生成物の異性体分離を行い、さらに二段階の化学合成を経て、単一異性体ＳP－１のＨＰＬＣ純度が９０％以上である高純度の化合物ＳP－１の組成物を製造する化合物ＳP－１リッチな組成物の製造方法。体外腫瘍細胞増殖抑制効果がＮＵＣ－１０３１及び化合物ＲP－１より顕著に高い化合物ＳP－１リッチな組成物、この組成物の用途、並びにこの組成物と少なくとも一種の薬学的に許容される賦形剤とを含む医薬組成物。【選択図】図７
