Phase I clinical trial of monoclonal anti-human chorionic gonadotropin antibody in women with an ectopic pregnancy

A phase-I clinical trial of a mouse monoclonal anti-human chorionic gonadotropin (hCG) antibody designated as HT13 was conducted in three patients treated for ectopic pregnancy. Doses of 5 and 25 mg of purified antibody were injected into patients. Monoclonal antibody serum levels dropped to 0 within 1 to 5 days. Human antibodies directed against mouse immunoglobulins were not detected at up to 41 days after injection. In one patient, the tubal pregnancy resolved, as confirmed by hCG levels of less than 10 mUl/mL and by tubal patency at hysterosalpingography. The time of resolution was 30 days. In two patients, salpingectomy was performed because of persistence of elevated hCG levels, whereas HT13 had a striking effect on progesterone (P) and estradiol (E2) serum levels. The injection of anti-hCG antibody did not appear to interfere with the subsequent fertility of patients, and two out of three patients later developed a successful pregnancy. While the precise role of antibody injection in the interruption of ectopic pregnancy remains speculative, the injection of monoclonal anti-hCG antibody appears to induce a dramatic decrease in the production of both P and E2.