Vivus: Savior of the Pharma Industry?
Obesity took center stage in September, with important clinical results released on two key products: Vivus Pharmaceuticals' Qnexa and Arena Pharmaceuticals' Lorcaserin. That follows the release of phase 3 results on Orexigen's Contrave, another serious obesity contender, in July. All had positive results, but--if we may compare apples to slightly different apples for a moment--Vivus was the standout. Patients on Qnexa for 56 weeks lost an average 37 pounds, or 14.7% of body weight. The other drugs, while successful, ranged between 6.1% and 6.5% reduction in body weight--still handily exceeding FDA's general guidelines for a new obesity therapy. Vivus shareholders were, not surprisingly, cheering the news.
Drug developers have long thought of the ideal weight-loss pill--highly effective, safe in a broad audience (to obese and casual dieters alike), with manageable and not-too-unpleasant side effects--as the philosopher's stone of pharmaceuticals. Such a drug could top $10 billion in annual sales and stand shoulder-to-shoulder with the mighty Lipitor. Or reach even higher.
On the other hand, history shows that weight loss drugs, in reality, don't fare that well. The notorious Phen-Fen combination was effective and (for a time) successful, but deadly. Drugs that block fat absorption like Alli and Xenical are only so-so effective and pretty unpleasant to use for most people. Bontril also comes with some serious side-effects and a danger of habituation, tolerance, and withdrawal, while Meridia just doesn't work all that well for many people.
And there's another reason for a note of caution: Qnexa and Contrave are both combinations of two existing generic drugs. As the In Vivo Blog points out, NitroMed thought it had a winner with its heart drug BiDil, also a combination of two generics, only to strike out big time in the marketplace, perhaps because it priced the combo too high and sent people scrambling for off-label generic alternatives. Could these weight loss drugs face similar challenges?
It's an interesting question, though the situations are still quite different. Phen-Fen enjoyed considerable commercial success for a while, after all, yet was also a combination of existing drugs. And it was never even an FDA approved medication--it was an off-label combination of phentermine (approved in 1959 and still available today) and fenfluramine (approved in 1973 but withdrawn in 1997). Redux, or dexfenfluramine, was the new commercial entry to the market in 1996 and looked to be heading for blockbuster sales before it was withdrawn in 1997.
In the case of Qnexa, which combines phentermine with the epilepsy drug topiramate in very low doses, it won't be so easy to turn to a generic alternative because the equivalent dosages don't exist in generic form, nor does the delivery mechanism which may play a role in reducing side effects. Plus, I'd like to think the marketing teams at these companies will learn from NitroMed's experience and not make the same mistakes.
Analysts are already suggesting Qnexa could reach peak sales of $1 billion, and if the safety profile holds up in future studies, they may not be overshooting the mark for once.
Read the BioPharm Executive online newsletter September 2009.
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More By Karl Thiel