Zinostatin and doxorubicin. A combination phase I study

Because of encouraging single-agent activity for both zinostatin and doxorubicin in hepatocellular cancer, a phase I tolerance study with these drugs in combination was undertaken. The dose of zinostatin given daily for 5 consecutive days and repeated every 6 weeks was fixed at 2250 units/M2. The starting dose of doxorubicin was 45 mg/m2 on days 1 and 22 of every 6-week cycle, but this was escalated or deescalated by increments of 33% as tolerated. The occurrence of unpredictable severe and prolonged cumulative myelosuppressive toxicity in most patients resulted in considerable management difficulties. In addition, three patients developed congestive heart failure at cumulative doxorubicin doses ranging from 195 to 270 mg/m2 and two patients developed possible drug-related nephrotoxicity. Until reasons for the pharmacogenetic variability observed with zinostatin are defined, combination studies employing this drug are not recommended.