Non-human primate (baboon) anti-carcinoembryonic antigen antibody infusion in patients with metastatic adenocarcinoma. A phase I study.

A total of 14 patients with advanced visceral carcinoma which produced carcinoembryonic antigen (CEA) were treated in a Phase I study with IV infusion of affinity purified baboon anti-CEA antibody (dosage range from 0.1 to 2 mg/kg body weight). In all 14 patients, the antibody infusion caused a decrease (26% to 97%) in the plasma level of CEA. The degree of decrease depended upon the patients initial CEA level and the amount of antibody given. In 12 of the 14 patients "free" circulating antibody was observed. The plasma half-life of the antibody ranged from 0.7 to 21 h and the duration of detectable free antibody ranged from 3 to 216 h postinfusion. No toxicity was observed for the dosage range of antibody tested. In 9 of the 14 patients a low titer anti-baboon antibody response occurred between 14 and 28 days postinfusion. No clinical regression of carcinoma was documented. In 7 of the 14 patients disease remained stable during the 28-day study period. By the end of the 28-day study period plasma CEA levels had returned to at least the preinfusion level in 11 of the 14 patients.