Cross resistance studies with L1210 leukemia subline single and double resistant to cisplatin and iproplatin (CHIP).

Resistance to cisplatin (DDP) and/or iproplatin (CHIP) was induced in vitro in murine L1210 leukemia cells. Double-resistant sublines with combined resistance to both drugs were also developed. Cross resistance investigations with DDP, CHIP, oxoplatinum (OXO), carboplatin (CBDCA) and its quadrivalent derivative OXOCBDCA were performed in these resistant sublines. Lack of cross resistance between DDP and CHIP was found. A higher resistance to CHIP in the double-resistant sublines was observed. A multistep process in the development of resistance to this compound is supposed. The importance of the aminoligand and the role of different pharmacokinetics in the cross resistance are discussed.