Phase I and pharmacokinetic study of sequences of the rebeccamycin analogue NSC 655649 and cisplatin in patients with advanced solid tumors.

PURPOSE: To evaluate the feasibility of administering NSC 655649, a water-soluble rebeccamycin analogue that inhibits both topoisomerases I and II, in combination with cisplatin (CDDP) in adults with solid malignancies. Major toxicologic and pharmacologic differences between the two sequences of drug administration were also assessed. EXPERIMENTAL
DESIGN: NSC 655649 was administered as a 60-minute i.v. infusion; CDDP was given i.v. before or after NSC 655649 on day 1. Each patient was treated with alternating drug sequences every 3 weeks; doses of each drug were escalated in separate cohorts of new patients. Sequential dose escalation of NSC 655649 or CDDP resulted in three dosage permutations of NSC 655649/CDDP: 440/50, 550/50, and 440/75 mg/m2. After the maximum tolerated dose level was determined, the feasibility of using granulocyte colony-stimulating factor to permit further dose escalation was explored.
RESULTS: Twenty patients were treated with 70 courses of NSC 655649/CDDP. Myelosuppression was the principal toxicity. The incidence of severe neutropenia, often associated with severe thrombocytopenia, was unacceptably high in minimally pretreated patients at the NSC 655649/CDDP dose level of 550/50 mg/m2 without and with granulocyte colony-stimulating factor. Major pharmacokinetic interactions between NSC 655649 and CDDP were not apparent. No relevant sequence-dependent differences in toxicity or pharmacokinetic variables occurred. Three patients had partial responses.
CONCLUSIONS: NSC 655649 and CDDP were well tolerated by minimally pretreated subjects at 440 and 50 mg/m2, respectively. Neither pharmacokinetic interactions between the agents nor sequence-dependent toxicologic or pharmacokinetic effects were apparent. The tolerance and preliminary activity observed with this combination suggest that disease-directed evaluations of the regimen are warranted.