Sulfonyl-Containing Aldophosphamide Analogues as Novel Anticancer Prodrugs Targeted against Cyclophosphamide-Resistant Tumor Cell Lines

A series of sulfonyl-group containing analogues of aldophosphamide (Aldo) were synthesized as potential anticancer prodrugs that liberate the cytotoxic phosphoramide mustards (PM, IPM, and tetrakis-PM) via β-elimination, a nonenzymatic activation mechanism. Kinetic studies demonstrated that all these compounds spontaneously liberate phosphoramide mustards with half-lives in the range of 0.08−15.2 h under model physiological conditions in 0.08 M phosphate buffer at pH 7.4 and 37 °C. Analogous to Aldo, the rates of β-elimination in all compounds was enhanced in reconstituted human plasma under same conditions. The compounds were more potent than the corresponding phosphoramide mustards against V-79 Chinese hamster lung fibroblasts in vitro (IC₅₀ = 1.8−69.1 μM). Several compounds showed excellent in vivo antitumor activity in CD2F1 mice against both P388/0 (Wild) and P388/CPA (CP-resistant) tumor cell lines.