Recombinant interferon-gamma (immuneron): results of a phase I trial in patients with cancer.

Recombinant DNA-produced interferon-gamma (rIFN-gamma) was administered intravenously to patients with solid tumors in a Phase I study. The rIFN gamma was prepared from Escherichia coli and purified to greater than 95% with a specific activity of greater than or equal to 30 X 10(6) units/mg protein. Twenty patients received intravenous bolus injections once weekly for 4 consecutive weeks. They were assigned to one of six dose groups ranging from 1 to 81 X 10(6) units/m2 body surface area; intrapatient dose escalation was not allowed. Patients were monitored intensively for toxicity, but no dose-limiting toxicity was demonstrated. Fever was the predominant side effect, occurring in all patients treated, and usually reached 38-40 degrees C. Short-term somnolence and fatigue were also observed, but no chronic fatigue was seen. Decreases in white blood cell and platelet counts, generally within the normal range, were observed; however, the counts rose again after intervals of 2-5 days. There was no firm evidence of a relationship between adverse effects and dose. No life-threatening side effects were noted and no antibodies developed to either rIFN gamma or E. coli proteins. The pharmacokinetics of rIFN gamma did not appear to alter from week 1 to week 4. Calculated half-lives were from 0.8 to 3.5 h. Doses greater than 9 X 10(6) units/m2 gave measurable serum levels for at least 12 h. A partial response of 8 weeks' duration was observed in a patient with hepatoma.