In 1960, the FDA approved Enovid, but the struggle for better birth control continues. Enovid, a female oral contraceptive, consisted of a mixture of hormones. For many women, hormone-based contraceptives are unacceptable. According to Samuel Lai, PhD, a chemical and biomolecular engineer at the University of North Carolina at Chapel Hill, and his colleagues: “Many women risk unintended pregnancy because of medical contraindications or dissatisfaction with contraceptive methods, including real and perceived side effects associated with the use of exogenous hormones.”

So, Lai and his colleagues developed IgG monoclonal antibodies that can be delivered directly to the vagina to trap and immobilize sperm.

The team created this contraceptive by bioprocessing immunoglobulin G (IgG) and tested it in sheep. Lai said that the most interesting finding in this work is “that we can readily modify IgG to achieve agglutination potencies comparable to IgM, but maintain the same bioprocessing ease of IgG, by simply stringing together additional Fab domains.” Although Lai said that this approach “seems conceptually straightforward and exceedingly simple,” no one had tried it. As Lai said, “It’s interesting to me how well it worked, allowing us to see exceptional potencies even with just tens of micrograms of antibodies dosed per sheep.”

When asked about the key obstacles to the bioprocessing, Lai said, “There weren’t many challenges, which was the point.” Nonetheless, just expecting  something to be largely straightforward is not the same as demonstrating that, which Lai’s team did. “In our hands, despite the large molecular weight of some of our constructs, they had bioprocessing ease and stability that matches if not exceeds the parent IgG.”

The team went on to develop this contraceptive under current good manufacturing processes (cGMP) and good laboratory practices (GLP). As Lai noted: “We made cGMP-quality materials and formulated them into vaginal films that meet GLP specifications, and saw 100% efficacy in sheep.”