Phase I study of echinomycin administered on an intermittent bolus schedule

We have conducted a phase I study of the cyclic peptide echinomycin (Quinomycin A) on a schedule of administration of once every 4 weeks. Ten dose levels between 20 and 1800 micrograms/m2 were studied. Acute gastrointestinal toxicity, thrombocytopenia, and transient elevations of serum transaminases occurred at doses of greater than or equal to 1000 micrograms/m2. Gastrointestinal toxicity was severe and dose-limiting in several patients at doses of 1800 micrograms/m2. Thrombocytopenia was erratic, but generally increased with drug doses. Platelet count nadirs occurred 5-10 days after administration. Hepatic toxicity was reflected in transient elevations of serum transaminases without hyperbilirubinemia. Three patients experienced apparent anaphylactic reactions to doses of 1500 micrograms/m2. The maximum tolerated single dose of echinomycin was 1800 micrograms/m2. A starting phase II dose of 1500 micrograms/m2 is recommended.