N4-Behenoyl-1-beta-D-arabinofuranosylcytosine as a potential new antitumor agent.

N4-Acyl-1-beta-D-arabinofuranosylcytosines, which are lipophilic antitumor analogs of 1-beta-D-arabinofuranosylcytosine, were dissolved by the use of a detergent, HCO-60, and the differences in the antitumor activities when the drugs were administered in the forms of solution or suspension were compared. N4-Stearoyl-1-beta-D-arabinofuranosylcytosine (NSC 201290), which was the most active compound when administered as an aqueous suspension, diminished in its activities after it had been dissolved into a clear solution, whereas N4-behenoyl-1-beta-D-arabinofuranosylcytosine (NSC 239336) exhibited activities superior to those of the parent compound 1-beta-D-arabinofuranosylcytosine when administered as a solution. Moreover, the high efficacy of this compound was long lasting in the host animal, regardless of the treatment schedules or the presence of the 1-beta-D-arabinofuranosylcytosine-inactivating enzyme, cytidine deaminase.