Antitumor activity and cross-resistance studies with Pt-ascorbato complexes

Two ascorbatoplatinum complexes, cis-diammineascorbatoplatinum(II) (AMA) and cis-bis(ascorbato)-trans-diaminocyclohexaneplatinum(II) (CHA), were tested for antitumor activity in vivo on P388 leukemia and in vitro in suspension culture and soft agar assay. Sensitive line of L1210 and sublines with resistance induced against cis-diamminedichloroplatinum(II) (DDP) and two derivatives of trans-1,2-diaminocyclohexane (DACH) were used for the in vitro tests. DNA synthesis inhibition in both sensitive and resistant cells was tested. The results are compared with DDP and DACH-Pt(II)-4-carboxyphtalate (TMA). Both tested complexes proved their antitumor activity in our experimental systems. The CHA complex was more effective than AMA and its effectiveness is comparable with that of DDP and TMA. Cross-resistance was found between DDP and AMA as well as TMA and CHA. There was no cross-resistance between DDP versus CHA, and TMA versus AMA.