Having a child is a big responsibility for both fathers and mothers. In the same way, for men and women who aren’t ready for a family, the responsibility of preventing a pregnancy belongs to both partners.
For men, contraception choices are limited. While condoms are effective, they have a 15 percent failure rate in real-world application. Vasectomies have become easier and more available, but they’re both expensive and might not be reversible in some men.
But another option—a safe, reversible and non-hormonal pill—could be around the corner, thanks to a discovery by Oklahoma Medical Research Foundation scientist Kevin L. Moore, M.D.
Moore’s lab was the first to identify and clone two closely related enzymes, called tyrosylprotein sulfotransferases (TPST) 1 and 2. In experiments, they found that mice lacking the second enzyme, TPST-2, were infertile.
“They couldn’t fertilize eggs,” Moore said. “Other than that, they seemed normal in every way.”
The mice created sperm, the sperm was motile, but it couldn’t bind with the egg to cause conception. Moore realized that a compound to block the action of the TPST-2 enzyme might act as a male contraceptive in men.
And an enzyme blocker would likely have fewer negative side effects than hormonal birth control, the kind most often used by women.
“In the last 60 years, science has developed a clearer understanding about the effects of hormonal contraceptives on women, including increased risk of breast cancer and cervical cancer,” said Moore, who is the Fred Jones Distinguished Scientist at OMRF. “Knowing what we know now, why would we want to mess with the hormones of the other half of the population?”
Blocking enzymes—the approach employed by the popular cholesterol-reducing drugs known as statins—can better target biological processes than the manipulation of hormones. And, said Moore, it should avoid a host of side effects, including weight gain and increase in bad cholesterol that can accompany treatment with hormone-based compounds.
And, said Moore, “An enzyme-blocker would be reversible”—an important fact for men who might later want a family.
According to Moore, the next step will be to identify compounds that block the TPST-2 enzyme. If these efforts are successful, years of drug development and testing would follow. The ultimate goal would be a male contraceptive pill. To that end, Moore started and is president of Siwa Biotech Corporation, which is working to identify and market a male contraceptive pill based on the enzyme research.
“This work holds great promise for the development of a safe and effective male contraceptive pill,” said OMRF President Stephen Prescott, M.D. ”The road to drug development and FDA approval is long and is fraught with uncertainty, but this discovery represents an important first step.”
OMRF (omrf.org) is an independent, nonprofit biomedical research institute dedicated to understanding and developing more effective treatments for human disease. Chartered in 1946, its scientists focus on such critical research areas as Alzheimer’s disease, cancer, lupus and cardiovascular disease.