Dual Gene Delivery Reagents From Antiproliferative Alkylphospholipids for Combined Antitumor Therapy.

Alkylphospholipids (APLs) have elicited great interest as antitumor agents due to their unique mode of action on cell membranes. However, their clinical applications have been limited so far by high hemolytic activity. Recently, cationic prodrugs of erufosine, a most promising APL, have been shown to mediate efficient intracellular gene delivery, while preserving the antiproliferative properties of the parent APL. Here, cationic prodrugs of the two APLs that are currently used in the clinic, miltefosine, and perifosine, are investigated and compared to the erufosine prodrugs. Their synthesis, stability, gene delivery and self-assembly properties, and hemolytic activity are discussed in detail. Finally, the potential of the pro-miltefosine and pro-perifosine compounds M E12 and P E12 in combined antitumor therapy is demonstrated using pUNO1-hTRAIL, a plasmid DNA encoding TRAIL, a member of the TNF superfamily. With these pro-APL compounds, we provide a proof of concept for a new promising strategy for cancer therapy combining gene therapy and APL-based chemotherapy.

Synthesis and Evaluation of Antitumor Alkylphospholipid Prodrugs.

PURPOSE: Hemolysis is a serious side effect of antitumor alkylphospholipids (APLs) that limits dose levels and is a constraint in their use in therapeutic regimen. Nine prodrugs of promising APLs (miltefosine, perifosine, and erufosine) were synthesized so as to decrease their membrane activity and improve their toxicity profile while preserving their antineoplastic potency. METHODS: The synthesis of the pro-APLs was straightforwardly achieved in one step starting from the parent APLs. The critical aggregation concentration of the prodrugs, their hydrolytic stability under various pH conditions, their blood compatibility and cytotoxicity in three different cell lines were determined and compared to those of the parent antitumor lipids. RESULTS: The APL prodrugs display antitumor activity which is similar to that of the parent alkylphospholipids but without associated hemolytic toxicity. CONCLUSION: The pro-APL compounds may be considered as intravenously injectable derivatives of APLs. They could thus address one of the major issues met in cancer therapies involving antitumor lipids and restricting their utilization to oral and topical administration because of limited maximum tolerated dose.

Erufosine (ErPC3) Cationic Prodrugs as Dual Gene Delivery Reagents for Combined Antitumor Therapy.

Sixteen cationic prodrugs of the antitumor alkylphospholipid (APL) erufosine were rationally synthesized to provide original gene delivery reagents with improved cytotoxicity profile. The DNA complexation properties of these cationic lipids were determined and associated transfection rates were measured. Furthermore, the self-assembly properties of the pro-erufosine compounds were investigated and their critical aggregation concentration was determined. Their hydrolytic stability under pH conditions mimicking the extracellular environment and the late endosome milieu was measured. Hemolytic activity and cytotoxicity of the compounds were investigated. The results obtained in various cell lines demonstrate that the prodrugs of erufosine display antineoplastic activity similar to that of the parent antitumor drug but are not associated with hemolytic toxicity, which is a dose-limiting side effect of APLs and a major obstacle to their use in anticancer therapeutic regimen. Furthermore, by using lipoplexes prepared from a prodrug of erufosine and a plasmid DNA encoding a pro-apoptotic protein (TRAIL), evidence was provided for selective cytotoxicity towards tumor cells while nontumor cells were resistant. This study demonstrates that the combination approach involving well tolerated erufosine cationic prodrugs and cancer gene therapy holds significant promise in tumor therapy.

Gold(I)-Catalyzed N-Desulfonylative Amination versus N-to-O 1,5-Sulfonyl Migration: A Versatile Approach to 1-Azabicycloalkanes.

Valuable 1-azabicycloalkane derivatives have been synthesized through a novel gold(I)-catalyzed desulfonylative cyclization strategy. An ammoniumation reaction of ynones substituted at the 1-position with an N-sulfonyl azacycle took place in the presence of a gold cation by intramolecular cyclization of the disubstituted sulfonamide moiety onto the triple bond. Depending on the size of the heterocyclic ring and substitution of the substrates, two unprecedented forms of nucleophilic attack on the sulfonyl group were exploited, that is, a N-desulfonylation in the presence of an external protic O nucleophile (37-87 %, 10 examples) and a unique N-to-O 1,5-sulfonyl migration (60-98 %, 9 examples).