Posts tagged ‘contrave’

QNEXA Advisory Committee follow up… Think about this

I’ve had a few days to think about this and still have a difficult time understanding the Advisory Committee vote. I admit that I didn’t see this coming. Maybe I should have. After all, this committee (with different members) gave a thumbs up to CONTRAVE. And what happened with CONTRAVE? The FDA went back to the basics of the drug approval process, the basics of benefit risk, and determined that the sponsor had not satisfied the regulatory requirements.

Will the same thing happen with QNEXA? I don’t know what the FDA will do, but I do know what they should do. Efficacy doesn’t seem to be an issue although there doesn’t seem to be any additional weight loss after 1 year of treatment. With the unanswered, it seems likely that if approved, use beyond one year will be limited.

But let’s look at the safety issues. The two biggies are sitting right out there – cardiovascular risk and teratogenic potential in women of child bearing potential. Both of these are unknowns at this time and both can be answered. The question for the FDA is whether the answers should come before approval or after approval.

Teratogenic risk: QNEXA is a teratogen. The population at risk has a high percentage of women of child bearing potential. The component responsible for the teratogenic risk is already available for the treatment or migraines and epilepsy in a population that contains women of child bearing potential. The issue here is not the approvability of the drug but rather the adequacy of the REMS program and the labeling. Can the FDA and the sponsor work this out before the PDUFA Date?

Cardiovascular risk. The FDA has raised this issue in both of their Briefing Documents. The previous Advisory Committee had this as one of the major outstanding issues they used to support its 6-10 vote against recommending approval. The FDA is concerned enough about cardiovascular risk with obesity drugs to call for another Advisory Committee meeting with this as the sole topic for discussion next month. Now, the interesting thing is that the upcoming Advisory Committee meeting is going to be another meeting of the Endocrine Metabolic Drugs panel, the same panel that just recommended approval for QNEXA. The FDA will probably invite a lot of cardiologists, more than were at the QNEXA meeting. The cardiologist vote for QNEXA was split, one for, one against approval. The negative vote was very negative. It is unlikely the FDA will make any decision about resolving the cardiovascular risk associated with QNEXA until after the March Advisory Committee. If the Committee continues to support the current FDA reequirement that studies that rule out cardiovascular risk must be completed before approval then the decision to be made by the FDA is obvious. If however, the Committee recommends that in some circumstances these studies can be conducted post approval, the question then becomes whether the FDA and the sponsor can work this out before the PDUFA Date. They would have to agree to the protocol for such a study and agree on labeling that identifies the absence of information that defines the population at risk.

I’m of a view now that QNEXA will be approved for the treatment of obesity. The questions of when and with what kind of a label still remain. It is unlikely it will be approved at its PDUFA Date. How long after the PDUFA Date is a question that can only be answered after the March Advisory Committee meeting. A point to keep in mind – while we are focusing on the approval of QNEXA, the FDA is also thinking about the precedent it will set for other drugs in the review/development pipeline.

Diet Drugs in 2012

We’ve had several questions from readers asking if our opinion on the diet drugs that failed in 2011 has changed. Specifically, will Qnexa (or by extrapolation) or any of the other diet drugs have an easier go of it the next time around, ie, is the Cupcake Commentary still valid?

We’re going to take a slightly different approach with this posting and give our readers an insight into one of the changes we are thinking about for 2012 and beyond. We’re going to provide a more detailed commentary in this, the first response to our new feature, the Readers Forum.

Let’s start with the basic criteria for approval from the FDA Guidance on Diet Drugs. The draft guidelines from 2007 state that to prove efficacy, a diet drug must have two adequate and well controlled studies that demonstrate:

After 1 year treatment either:

  • There is a difference of 5% or greater between placebo and active drug OR
  • Greater than 35% of patients treated with drug have a difference of greater than 5% from baseline and twice the difference from placebo.

In earlier postings, we pointed out that the 5% difference is a very modest decrease in weight for a year and is comparable to having one less cupcake a week for a year for a 200 pound person. (200 lbs x 5% = 10 pounds; 10 lbs/52 weeks = 0.192 pounds per week, or about 3 oz, the size of a typical cupcake).

Let’s look at the data that were reported in the Briefing Documents prepared by the sponsors and the FDA for the Advisory Committee meetings that were held to discuss the diet drugs submitted for approval.

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Let’s look at the alternatives to diet drugs. On one side are the diets and exercise that offer limited benefit and little risk. From purely anecdotal reports, if would appear that the General Motors Diet is the most successful. Many have not heard of this diet because nobody can make any money writing about it. It is the diet that has been used by the General Motors health professionals for years and is freely available on the Internet. Success is often reported as 5% weight loss in a week and safety is not an issue. Attendant with the success is often a change in eating habits.

On the other side of the diet drugs is gastric bypass surgery and its alternative, the stomach band. Success is reported as high as 30% weight loss in a year, a normalization of the diabetic state and a change in eating habits. Safety concerns include those associated with surgery and potential long term metabolic changes. It should be noted that this extreme surgical intervention is limited to those identified as obese and there is significant pre-screening qualification before the surgery and extensive monitoring afterward.

So, as a generality, diets can be said to be the least effective (as measured by sustained weight loss) for the majority of people but the safest, while gastric bypass surgery is currently the most effect but carries the most danger. Diet drugs tend to be between these two extremes, marginally more effective than diet alone but significant potential for more adverse effects.

Of course, the patient populations of these three treatments tend to be different. Diet and exercise is a treatment available to anyone, diet drugs for patients who need a bit more than the diet and exercise and bypass surgery generally reserved for those described as obese.

The FDA and its Advisors must determine if the diet drugs are safe and effective for the intended population, that is, those who fail diet and exercise alone but not so obese that they require bypass surgery.

Is there a regulatory precedent for this kind of treatment and this kind of population? I say yes. Recall the acne treatment isotretinoin or ACCUTANE as it was first marketed. Acne is a disease that can be treated with non-prescription drugs in the mildest condition, prescription drugs for those who don’t respond to the non-prescription drugs and for the most severe forms of acne, treatment with ACCUTANE is effective. Also like the use of diet drugs, acne treatment has a certain cosmetic component to it. By that I mean while there are certainly positive health components to treating both obesity and acne, treatment of both also usually results in a more attractive individual.

The ACCUTANE approval was held up because, like some of the diet drugs, it produced birth defects. The conventional wisdom whispered but never overtly expressed at the time was that this was a time bomb waiting to explode. One potential patient group was women of child bearing potential and clearing up acne had the potential to make their child bearing potential greater. Very restrictive labeling was proposed and rejected. The approval of ACCUTANE was delayed while this aspect of benefit risk was debated. When it was approved, and to this day, it carries a severe restriction requiring that women of child bearing potential have 2 negative pregnancy tests and be using 2 methods of birth control before it can be prescribed to them.

There is no reason to believe that the FDA has reduced its standards for drugs that have a potential for birth defects, especially if the drug has the potential for wide spread use in women of child bearing potential. Like ACCCUTANE, diet drugs have the potential to to make the child bearing potential of women of child bearing potential more potential.

Vivus has resubmitted its NDA for QNEXA with requested additional cardiovascular safety data to address issues that arose during the previous NDA review. These data will be reviewed at an upcoming Advisory Committee in February when the committee will have the opportunity to see the FDAs view of these limited data. It is likely the FDA will also ask the committee to comment on QNEXA use in women of child bearing potential, perhaps the reason the FDA has not insisted on included this population as a contraindication. Or perhaps they just feel it doesn’t make any difference because the drug still doesn’t have a benefit risk ratio that justifies approval.

NEXT TIME: Is it time for the FDA to revise the Guidance document for drugs used to treat obesity?

CONTRAVE Revisited

Yes, we know that all of the bells have tolled for Contrave – even the fat lady’s final notes have faded, but we feel compelled to comment on the Orexigen announcement that they have put their plans for Contrave on hold because they failed to convince the FDA that their plan to study the potential cardiovascular effects was sound.  Equally interesting to us was the comment made that such action by the FDA challenges the development of obesity drugs in the US.

We have been consistent in our opinion of the three obesity drugs that were before the FDA during the past year.  Uniformly, they either didn’t meet the very lenient efficacy requirement or in fact failed it.  Recall our cupcake commentary – 5% weight loss over the course of a year for a 200 pound person is the equivalent of one cupcake a week.  Remember also, it is all about benefit risk with the FDA.  With such a lenient efficacy requirement, it is understandable that the FDA expects a very clean safety profile.

There is a case for the continued evaluation of obesity drugs in the US.  With all the reports confiming that we are a society that is becoming more and more obese, dieting and will power don’t seem to be able to control the trend.  So how about developing a drug that is as effective as gastric by pass with 25% weight loss not uncommon in the year following surgery.  Such a weight loss with the accompanying reduction in co-morbidities associated with obesity may just get the benefit risk to a position that the FDA finds acceptable.