[Antitumor effect of 1,3,3,5,5-pentaziridino-1-thia-2,4,6-triaza-3,5- diphoshorine-1-oxide].

The antitumor activity of 1.3.3.5.5-pentaziridino-1-thia-2.4.6-triaza-3.5-diphospho rine-1-oxide (SOAz) was investigated in vitro and in vivo. The results obtained were as follows: SOAz showed marginal cytotoxicity against growth of L1210 cells cultured in vitro. In the cell-cycle traverse of RPMI 8402 cells, SOAz prolonged the duration of the S phase, leading to the eventual accumulation of cells at the G2 phase. At the highest concentration, SOAz stopped the cell cycle progression completely. SOAz was found to have similar activity to carbazilquinone, cyclophosphamide or mitomycin C on P388 leukemia. SOAz showed marked antitumor effect against early-stage L1210 leukemia, and was also effective against advanced-stage L1210 leukemia. The therapeutic efficacy of SOAz depends on the treatment schedule. Single injection and intermittent treatment were superior to daily treatment. Oral administration of SOAz was effective as well as i.p., i.v. and i.m. administration.