Thank you for the opportunity to speak today. I am Dr. Christina Silcox, I have a PhD in Medical Engineering and Medical Physics from MIT, and I am a senior fellow at the National Center for Health Research. Our research center scrutinizes scientific and medical data and provides objective health information to patients, providers and policy makers. Those are the perspectives I bring with me today. We do not accept funding from pharmaceutical companies so I have no conflicts of interest.
The Center strongly supports research to advance understanding of, and solutions to, women’s lack of sexual desire. We understand that it is a real and distressing problem for many women.
We have followed the regulatory history of flibanserin. Based on our analysis of the study results available today, we conclude that the benefits of this drug do not outweigh the risks.
We ask the Advisory Committee to vote against approval of this drug.
We acknowledge there may be a small positive effect on the distress women feel and the number of satisfying sexual events per month. The effect on desire depends on measurement technique, but there may also be a small effect.
With such a substantial placebo effect and a very small benefit of the drug, is flibanserin safe enough to justify approval? We would say no.
#1: The drug was studied on very healthy, premenopausal women for generally less than a year of continuous use but would be taken for much longer IF it is effective. The data from these studies show that taking flibanserin increases the likelihood of low blood pressure, fainting, and other potentially serious adverse events including appendicitis, which is quite concerning. This risk is increased when women are on hormonal birth control. The high drop-out rate from the study adds to these concerns, since it suggests adverse reactions that might be ignored for women who are not in a clinical trial. In addition, we can’t know the risks for women already taking a long list of common medications, including blood pressure drugs and anti-fungals, because they were excluded from all three pivotal studies.
#2. The study shows a dangerous interaction with alcohol for men, but we don’t know the risks for women since the alcohol study included only 2 women. For a drug that will only be taken by women. By a company that claims to champion women. It is well known that alcohol metabolism differ for men and women, and alcohol metabolism decreases dramatically right after a woman ovulates each month. Sprout should have done this study with a large group of women of different ages. Because they didn’t, we don’t know the risks of alcohol for women but they are likely to be higher than they are for men.
#3. Equally important, what are the risks of developing breast cancer when taking flibanserin year after year? The risk of mammary gland tumors in mice increased with dosage, which experts consider an important safety risk, especially at levels so much below 100 times the human dose. This suggests a link to cancer, but, since the control mice in the study had fewer tumors than historical controls, those data are difficult to interpret.
When you consider the mouse data as well as the genotoxicity result in one of the in vitro tests, there are too many red flags to ignore. Sprout should repeat the study again with a mouse strain that has a lower and more predictable baseline rate of mammary tumors.
In conclusion, we strongly support FDA’s previous decisions to deny approval for a drug with minimal benefits that has so many unknown risks. The risks that we know about are reason for concern. . But it’s the risks that we don’t know about — due to Sprout’s research decisions– that are the most serious. Unfortunately, time does not permit me to expound on other issues.
In conclusion, until the sponsor is willing to take the research as seriously as they take their PR campaign, I urge you to vote AGAINST approval.
These comments may be edited for length at the FDA meeting.