Stephanie Fox-Rawlings, PhD, National Center for Health Research: November 1, 2018
Thank you for the chance to speak today on behalf of the National Center for Health Research. I am Dr. Stephanie Fox-Rawlings. Our Center analyzes scientific and medical data to provide objective health information to patients, health professionals, and policy makers. We do not accept funding from drug and medical device companies, so I have no conflicts of interest.
As we’ve heard today, depression is a serious health issue. However, FDA approval requires proof that new drugs are safe and effective. New drugs have to work to help patients.
I’ll focus on efficacy first. The evidence presented for buprenorphine/samidorphan (BUP/SAM) does not provide adequate evidence that it reduces depression more than placebo.
Two of the three trials designed to provide evidence of efficacy did not find any statistical benefit of the drug compared to placebo. The third trial, study 207, had a statistically significant reduction in depression on the MADRS for the 2mg/2mg dose. However, this trial also has major shortcomings. For example, it used the MADRS-6, which lacks important aspects of depression and therefore can’t prove efficacy.
Using the full MADRS, the only time the drug is more effective than placebo is for just a few weeks in the middle of a short trial. By the end of the trial, the placebo group was doing as well as the treatment group. This does not demonstrate a meaningful benefit for patients. And though statistically significant for that short time, treated patients improved less than 2 points more than placebo on a 60 point scale. This difference seems too small to be clinically meaningful for patients.
MADRS has clear standards for improvement. “Responders” are defined as those whose symptoms improve by at least 50%. Remission is defined by those scores are 10 or below on MADRS. Patients taking the drug were not more likely to be a responder or go into remission than patients taking placebo for any of the efficacy trials. This again raises questions about whether the benefit in study 207 is clinically meaningful compared to studies of other antidepressants. These trials may just be too short, but there needs to be confirmatory evidence that the statistically significant result is real.
Study 202 was designed as a proof of concept study and FDA points out that it can’t prove efficacy because it lacks the statistical controls to make sure that the difference did not occur by chance. Also, the relatively high dropout rate for patients in the drug arms could have a large effect on the results. We agree with the FDA reviewers that the lack of a dose response also raises red flags. If the drug is effective, the high dose (8mg/8mg) should at least show a statistical trend toward significance. It doesn’t.
As we all know, in studies of depression the placebo groups often do quite well. Placebo controls are essential because they help control for the natural ebb and flow of depression episodes. Instead, the sponsor tries to eliminate evidence of the placebo effect. Without the trial-long comparison of the placebo to drug arms, it is not possible to determine whether natural fluctuations in depression or the treatment are affecting the results.
There are concerns about safety.
The clinical trials included very few older patients. Older patients metabolize drugs more slowly and are more likely to have adverse reactions. They are also likely to be taking many other drugs that could interact with this drug.
Like all opioids, even ones with abuse-deterrent properties, this drug has the potential for misuse and abuse. This is a major concern because depressed patients are more likely to have substance abuse disorders and are at increased risk for opioid overdose.
In summary, the clinical trial data do not provide adequate evidence that BUP/SAM reduces the symptoms of depression. There are concerns about it potential for long-term harms to patients and others who might misuse or abuse it. BUP/SAM needs to provide strong evidence of efficacy before approval.
Although refractory depression is a serious condition, prescribing a treatment with unproven benefits and unknown risks is very dangerous. And, as you know, new drugs for depression tend to be more widely prescribed than the narrow indications that FDA approves. Approving this drug even for refractory depression could easily contribute greatly to our current opioid epidemic.
The joint Psychopharmacologic Drugs Advisory Committee and the Drug Safety and Risk Management Advisory Committee voted against approval (21 against and 2 for).