Organo-phosphorus compounds S 0080Novel Class of Cyclophosphamide Prodrug: Cyclophosphamide Spiropiperaziniums (CPSP). -Title compounds (III) (no yields given) are evaluated for in vivo anticancer activities against S180 and H22. The most potent derivatives (IIIb) and (IIIc) reveal a similar antitumor activity as cyclophosphamide (I). Furthermore, (IIIb) also exhibits much lower toxicity than (I). -(SUN, Q.; LI, R.-T.; GUO, W.; CUI*, J.-R.; CHENG, T.-M.; GE, Z.-M.; Bioorg.