Part I (previously untreated or minimally pretreated patients): The first patient of each cohort receives cisplatin IV over 1 hour followed 2 hours later by a rebeccamycin analogue IV over 1 hour on day 1. The second patient in the same cohort receives the same drugs in the reverse order. The drug sequence for each additional patient within the same cohort is alternated with reference to the preceding patient. During each subsequent course, the study drugs are administered to each patient in the reverse order as compared to the prior course. Treatment repeats every 3 weeks for 4 courses in the absence of disease progression or unacceptable toxicity.