A decisive step towards sharing responsibility for contraception within heterosexual couples may have just been taken. A team of scientists announced on Wednesday March 23 that they had developed a male contraceptive pill that is 99% effective in mice without causing any visible side effects. It could be tested on men by the end of the year.
>> Male contraception: why doesn’t the pill (still) work for men?
Previous attempts to develop a male pill tried to mimic the functioning of the female pill by acting on a male hormone, testosterone. But these trials caused unwanted side effects such as weight gain, bouts of depression and increased cholesterol levels, which increase the risk of heart disease. The female pill also causes side effects, such as an increased risk of blood clots.
To develop a non-hormonal pill, the team behind this new discovery targeted a protein, the retinoic acid receptor alpha (RAR-alpha). This acid plays an important role in cell growth, sperm formation and embryo development. During their laboratory experiments, the researchers showed that mice whose functioning of the RAR-alpha receptors was blocked became sterile.
The team, funded by the American Institutes of Health (NIH) and the non-profit organization Male Contraceptive Initiative, therefore developed a compound called YCT529 to block the action of RAR-alpha.
The first results are spectacular: administered orally to male mice for four weeks, YCT529 drastically reduced sperm production and was 99% effective in preventing pregnancy, with no side effects observed. And six weeks after stopping the ingestion of YCT529, the mice could reproduce again.
“There is no guarantee of success… but I would be really surprised if I didn’t see an effect on humans as well”, welcomed Professor Gunda Georg, who participated in the work. The detailed results of the experiments are to be presented at the spring conference of the American Chemical Society. Progress could be rapid: the teams behind YCT529 are working with YourChoice Therapeutics to begin clinical trials in the second half of 2022.