US researchers have identified a compound that may offer the first effective and hormone-free birth control pill for men.
The discovery, reported in medical journal Cell, is of a small molecule which the researchers found makes male mice reversibly infertile without destroying their sex drive.
“A pharmacologic approach to male contraception remains a longstanding challenge in medicine,” the researchers, from the Baylor College of Medicine, University of Oxford and Harvard Medical School, said in the report.
“Toward this objective, we explored the spermatogenic effects of a selective small-molecule inhibitor (JQ1).”
Harvard Medical School’s James Bradner said JQ1 is a new small molecule inhibitor of a bookmark placed throughout human genomes at regions of chromatin that are associated with gene activation.
“We developed JQ1 in my laboratory first as a cancer therapeutic with the idea that we might cause cancer cells to forget, in effect, that they are cancer,” Dr Bradner said.
With the discovery that JQ1 effectively blocks the cell division necessary for normal sperm production, the researchers have also demonstrated quite clearly that it’s possible to separate the male hormonal production of testosterone from sperm production and that you can interfere with one without interfering with another, said David de Kretser, founding director of the Monash Institute of Medical Research.
“It’s a nice piece of work which describes a process that can be interfered with in terms of sperm development which basically does not interfere with the hormone secretions of the testis which define sex drive and masculinity,” Professor de Krester said.
But couples looking for a quick and easy male contraceptive option might be disappointed.
“This was developed by injection - I’m not sure it would survive being given by a pill,” Professor de Krester said. “The next step really would be trying to see if you could find a molecule that survived being swallowed.”
The development of a potential new contraceptive is also likely to very long and arduous process leading up to the first human studies, said Robert McLachlan, director of clinical research at Prince Henry’s Institute of Medical Research.
“This requires industry partners, who at this point in time have been reluctant to engage in male contraceptive initiatives because of concerns such as side effects, efficacy and the size of the potential market,” Professor McLachlan said.
However Moira O’Bryan, head of the Male Infertility and Germ Cell Biology Laboratory at Monash University, said the medical and social costs of unplanned pregnancies are enormous and studies from both academics and drug companies have repeatedly shown that there is a strong desire for male-based contraceptives.
“Although there is undoubtedly an urgent need for additional contraceptive options, the path between this paper and a new product is likely to be long,” Professor O’Bryan said.
“Several doses of drug will need to be tested and the method of delivery improved. Frequent injections are unlikely to be acceptable to many.”
“It will be fascinating to see how JQ1 evolves, but we know that such pipelines may require 15 years of evaluation and there are many potential pitfalls along the journey,” Professor McLachlan said.