What Investors Need To Know About The Efficacy Of Belviq

| About: Arena Pharmaceuticals, (ARNA)

Arena Pharmaceuticals (NASDAQ:ARNA) has a new drug that recently had its label approved by the DEA. That drug is called Belviq.

There seems to be some confusion about the efficacy though.

Consumer Reports reported last Thursday in an article "Weight-loss pill Belviq is now available, but we say skip it" that the efficacy is 3 to 3.7%. The actual efficacy as declared clearly on the DEA label is 7.9% from the baseline of 100kg (220.9 pounds).

Let's clarify what the numbers actually are:

The 3% to 3.7% that was quoted in the Consumer Reports article and others is not the efficacy for the target group responders to Belviq. That number is an average of the entire test group including responders and non responders. Therefore that number does not represent the efficacy for responders, which are the target for Belviq.

  1. The efficacy is reported on the DEA label as 7.9%.
  2. The target beneficiary group is 47.1% of subjects.
  3. That means that 52.9% are non responders and this goes to the churn as those non-responders will likely be discontinued after 12 weeks.
  4. The DEA label clearly indicates that 47.1% of patients will lose greater than or equal to 5% of their body weight.
  5. The DEA label clearly indicates that 22.4% of responders will lose greater than or equal to 10% of their body weight.

There is a persistent tumor rumor that seems to be also misunderstood.

Consumer Reports repeated it in their article as well: "The FDA's advisory panel initially rejected Belviq because of a risk of tumors found in animal studies."

For investors, "recent" reports are better than "initial" reports -- especially when there seem to have been issues with the initial reports. A carefully controlled blind reanalysis by a pathology working group went through the tissue samples and found that much of the initial results were wrong apparently due to reporting errors. Read the "FDA Briefing Document NDA 22529 Lorcaserin (Belviq)" from the May 10, 2012 Meeting of the Endocrinologic and Metabolic Drugs Advisory Committee and note the findings. The data indicates various ranges of 'safety' pertaining to tumor development in relation to dosage ranging from 5-fold up to a 70-fold margin for various forms.

Another seemingly persistent rumor is that the European Medicines Agency rejected the drug. This is not true though. The European Medicines Agency did not reject the drug, Arena pulled the application in order to allow completion of studies that would alleviate concerns. Arena reported when they announced that they pulled the application their intention to reapply with the European Medicines Agency for approval of Belviq after those concerns were addressed.

In Summary

The DEA label is clear:

  1. The efficacy for Belviq is at least 7.9% in 47.1% of patients.
  2. 47.1% of patients lose greater than or equal to 5% of body weight.
  3. 22.4% of patients lose greater than or equal to 10% of body weight.
  4. From a baseline of 100kg (220.9 pounds), 47.1% of patients lose 11 pounds of more.
  5. From a baseline of 100kg (220.9 pounds), 22.4% of patients lose 22 pounds or more.

In other words, the efficacy for Belviq can be as high as 11% or better in 22.4% of patients in the target responder group.

Disclosure: I am long ARNA. I wrote this article myself, and it expresses my own opinions. I am not receiving compensation for it (other than from Seeking Alpha). I have no business relationship with any company whose stock is mentioned in this article.