In in vitro studies, no turnover of aldophosphamide and mafosfamide wa
s observed with the tumor-specific aldehyde dehydrogenase 3 isozyme (A
LDH3) isolated from human stomach mucosa as well as from lung (A549) a
nd pharynx (UMSCC2) carcinoma cell lines. Only the human liver cytosol
ic ALDH preparation (ALDH1) showed any significant oxidation of aldoph
osphamide and mafosfamide.