Two vaccines inducing antibodies against human chorionic gonadotropin (hCG) have completed Phase I clinical trials, indicating the reversibility and safety of these vaccines. One is currently in Phase II efficacy trials in women in three major centres in India. The available data suggest that the vaccine prevents pregnancy above antibody titres of 50 ng/ml hCG bioneutralization capacity.
PIP: Birth control vaccines inducing antibodies against human chorionic gonadotropin (hCG) are in the forefront of development among all potential birth control vaccines. 2 such vaccines have been developed; one of them uses the 37-amino acid carboxy terminal peptide of beta-hCG (the CTP vaccine), and the other employs the entire beta-hCG (the beta-hCG vaccine) or its heterospecies dimer with an alpha subunit for ovine luteinizing hormone (the HSD vaccine). A Phase I clinical trial with the CTP vaccine was conducted in Australia in 39 women, 10 serving as controls and 20 immunized with the vaccine. No important adverse reactions were observed and the immune response was reversible. Menstrual pattern was unchanged. More extensive Phase I clinical trials were conducted with the beta-hCG/HSD vaccines in 5 centers in India and in Finland, Chile and Brazil which invariably confirmed the lack of side effects and the reversibility of the vaccine. The HSD vaccine proceeded to Phase II trials conducted in 3 major centers in India. 14 women were exposed to the risk of pregnancy for 12 months and 2 completed 19 months without becoming pregnant. As of February 1, 1992, 642 cycles of exposure had been recorded. Only 1 pregnancy had taken place above the threshold level of 59 ng/ml bioneutralization capacity. Research results also indicate that a recombinant vaccine in a live vector such as vaccinia would require less frequent injections, and elicit a high antibody response capable of preventing pregnancy. Vaccines have entered Phase 1 clinical trials employing vaccinia as a vector as potential vaccines against the human immunodeficiency virus (HIV). Vaccination-inducing antibodies against hCG may have an application in the treatment of lung cancer, as a cell line, ChaGo, developed from a human lung cancer patient, makes hCG and its subunits.