Phase I study of i.v. administered recombinant gamma interferon in cancer patients

We report a phase I study of the biological effects, tolerance, and pharmacokinetics of 6- and 24-hour iv infusions of recombinant interferon-gamma (rIFN-gamma) in cancer patients. Twenty-one patients received the 6-hour iv infusion regimen at doses ranging from 0.016 to 0.65 mg/m2/day. Forty-one patients received the 24-hour iv infusion regimen at doses ranging from 0.01 to 0.05 mg/m2/day. Fever and flu-like symptoms were the most common side effects and were seen at all dose levels. The maximum tolerated dose was 0.16 mg/m2 for the 6-hour regimen and 0.01 mg/m2/day for the 24-hour regimen. A dose-dependent granulocytopenia was observed at doses greater than or equal to 0.05 mg/m2/day. A marked increase in beta2 microglobulin occurred by Day 5 of treatment in almost all patients, regardless of the dose level. Consistent serum levels of rIFN-gamma were achieved only at doses of 0.325 mg/m2/day of the 6-hour infusion. The mean serum concentrations at this dose ranged from 18 to 83 units/ml as measured by bioassay (0.64-2.4 ng/ml by enzyme-linked immunoassay). Antibody against rIFN-gamma did not develop in any patient. During the short period of evaluation of this study, one patient with renal cell carcinoma achieved a partial response, and three patients with renal cell (two) and lung carcinoma (one), respectively, achieved minor responses. This study will form the framework for phase II efficacy trials of iv rIFN-gamma.