The present invention provides a pharmaceutical composition comprising at least one hydrophobic camptothecin derivative or a pharmaceutically acceptable salt of said derivative and a polyethylene glycol (PEG) conjugated phospholipid. Also provided is a method to inhibit cancer cells in a subject in need thereof by administering the pharmaceutical composition of the present invention.本發明提供一種醫藥組合物,其包含至少一種疏水性喜樹鹼衍生物或該衍生物之醫藥學上可接受之鹽及結合聚乙二醇(PEG)之磷脂。亦提供一種藉由投與本發明之該醫藥組合物來抑制有需要之個體的癌細胞的方法。