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Progress Toward Male Birth Control Pill?

Pill Would Inhibit Sperm Production, but It May Not Be Available for Several More Years

By Salynn Boyles
WebMD Health News

Reviewed by Louise Chang, MD

Aug. 16, 2012 -- The promise of a safe and effective birth control pill for men has long eluded scientists, but a new approach could change that.

Researchers have identified a small molecule compound that inhibits sperm production, and they say it could lead to the first non-hormonal, easily reversible male contraceptive since the introduction of the condom centuries ago.

So far, it's only been tested in mice. In early studies, mice treated with the molecule had lower sperm counts than untreated mice, and their sperm were slower swimmers.

The treatment effectively rendered the mice infertile without affecting their desire to mate, says researcher James Bradner, MD, of the Dana-Farber Cancer Institute.

And sperm counts rebounded quickly once the treatment was stopped.

The next step, Bradner says, is to develop a more selective version of the molecule that could be safely used in human males.

"It will take some creative chemistry to make this happen, but I think we are up to the challenge," Bradner says.

Birth Control Options for Men Limited

It has been 50 years since the birth control pill for women was introduced, forever changing contraception for women.

But men who want to practice birth control have the same two commercial options that they have had for many decades: vasectomy and condoms.

Research to develop a birth control pill for men has largely focused on manipulating male sex hormones, but this approach has proven challenging, says William J. Bremner, MD, PhD, of the University of Washington School of Medicine.

One major challenge has been the presence of a sperm-testis barrier, which prevents larger molecules from reaching the site where sperm production occurs.

The small molecule compound developed in the Dana-Farber lab, known as JQ1, easily crosses this barrier.

JQ1 targets a testes-specific protein called BRDT that is critical for sperm production.

'Non-Hormonal Male Pill Years Away'

The compound was developed as a potential new treatment for cancer. Besides BRDT, it also targets another protein associated with tumor growth.

Trials in cancer patients will soon be under way, and Bradner says they could provide some early clues about whether or not the approach will work as a male contraceptive.

"We could get a sneak peek at the effect of this type of drug on sperm production," he says.

Along with colleague Martin Matzuk, MD, of Baylor College of Medicine, where the studies in mice were conducted, the Dana-Farber team is also working to develop a drug that specifically targets BRDT.

That is important because the more specific a drug is, the safer it is likely to be.

Bremner tells WebMD that earlier attempts to develop a non-hormonal male pill have failed because the drugs were not specific enough to turn off sperm production without causing unintended harm.

Though Bremner says he is optimistic that new birth control options for men are on the horizon, he says a non-hormonal male pill is, at best, several years away.

"We are probably not talking about something that is going to be available in the next two years or even five," he says. "But this research represents a new biologic approach and it is certainly promising."

The research appears in the Aug. 17 issue of the journal Cell.

SOURCES: Matzuk, M.M. Cell, Aug. 17, 2012. James Bradner, MD, assistant professor of medicine, Harvard Medical School; physician and scientist, Dana-Farber Cancer Institute, Boston. William Bremner, MD, PhD, professor and chairman, Department of Medicine, University of Washington School of Medicine, Seattle. News release, Cell Press, Aug. 16, 2012. News release, Baylor College of Medicine, Aug. 16, 2012.

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