- Patients must have concluded prior therapy no less than the duration of one cycle of treatment prior to beginning treatment with rebeccamycin analog, but in all cases there must be at least a 2 week interval since last treatment; thus, if a patient is receiving therapy every three weeks, the patient must be at least three weeks from the last treatment before beginning protocol-based therapy; patients must have recovered from the toxicities of prior therapy, and meet the performance status and laboratory criteria for eligibility before beginning treatment