7-con-O-Methylnogaril (menogaril, NSC-269148) is a new anthracycline antibiotic that has been evaluated in a Phase I clinical trial. The drug was administered in a single i.v. infusion over a period of 60 min given every 3 weeks. Twenty-four patients received 64 courses of the drug in a dose range of 16 to 256 mg/m2. Granulocytopenia was dose limiting and prolonged, requiring treatment delay in 5 of 9 patients treated at doses greater than or equal to 192 mg/m2. Concentration dependent phlebitis occurred in 12 patients, and was of minimal severity when the menogaril concentration was less than 1 mg/ml. Hair loss was experienced by 8 patients but was generally mild with only one patient developing total alopecia. Possible acute cardiac toxicity was noted in one patient who had a transient episode of atrial fibrillation following his fifth course of menogaril. Phase II studies of 7-con-O-methylnogaril are planned at a starting dose of 160 mg/m2 for patients with prior chemotherapy or radiotherapy, and 200 mg/m2 for those without prior therapy given at 28-day intervals.