Why the FDA Keeps Saying 'No' to Diet Pills

 |  Includes: ABT, ARNA, RHHBY, SNY, VVUS
by: Pharmalot

Earlier this year, there was nothing short of hoopla surrounding the notion that a new trio of diet drugs may win FDA approval. Why? Obesity remains a huge health problem (no pun intended) and there hadn’t been a new prescription diet pill since Roche’s (OTCQX:RHHBY) Xenical arrived in 1999. And with FDA advisory committee meetings planned, the reasoning went that the agency saw the need for a new therapy.

All of which made sense, to a point. But this is an era when the FDA is under pressure to ensure that safety is a high priority. And rightfully so, given recent controversies over manipulation of clinical trial data and side effects surrounding various meds, as well as agency infighting. Diet pills, however, have merited special attention thanks to the 1997 withdrawal of part of Wyeth’s fen-phen cocktail.

The FDA may recognize a need for drugs that help people lose weight, but at what cost? How much safety risk can be tolerated when drugs offer little to modest weight loss? Such scrutiny led Sanofi-Aventis (NYSE:SNY) three years ago to give up on winning FDA approval for Acomplia due to psychiatric side effects (see this). And three weeks ago, Abbott Laboratories (NYSE:ABT) reluctantly withdrew its Meridia pill.

So is it really a surprise that Vivus (NASDAQ:VVUS) failed to win approval for Qnexa, which the fledgling drugmaker announced last week? Or that Arena Pharmaceuticals’s (NASDAQ:ARNA) Lorqess was rejected this month? No. In both cases, the agency issued complete response letters underscoring safety concerns. With Lorqess, the FDA cited marginal efficacy and controversial oncerns about trials showing tumors in rats (back story).

With the Vivus drug, the FDA wants the drugmaker to provide evidence its Qnexa pill does not elevate cardiovascular risks and to evaluate any potentially harmful effects on a fetus. Of course, the drug may yet get approved and the wait may not be indefinite, given the agency seems focused on REMS warnings and did not request new studies. Then again, it could (see the Vivus statement).

Given than an FDA advisory committee voted 10 to 6 last summer to reject Qnexa, the FDA move is hardly shocking, even though clinical trials showed patients on the highest dose lost an average of 10.6 percent of their weight after one year, compared with 1.7 percent for those on a placebo. Qnexa, by the way, combines phentermine (the surviving half of fen-phen) and topiramate, which is sold as Topamax and can cause psychiatric side effects and an irregular heartbeat.

Such issues have failed to deter Japanese drugmakers, which are desperately seeking a beachhead in the US market, from investing in diet drugs. Eisai paid $50 million for the rights to sell Arena’s Lorqess and Takeda Pharmaceuticals is giving Orexigen Therapeutics $50 million for exclusive North American marketing rights to its Contrave pill, which an FDA panel will review in December (back story). But as we have noted previously, such bets should be made with caution.

The FDA may yet approve Lorqess or Qnexa if enough concerns are dispelled. And perhaps Contrave will fare better, although the FDA review will not be available for several weeks. But even if one or more of the pills do eventually make it to pharmacy shelves, the drugmakers will be forced to maintain strict REMS programs. Investors, in particular, would do well to recall that safety is the catchword. Some may argue the pendulum at the FDA has swung too far in one direction, so far that, perhaps, some agency staffers are overly zealous. But unless or until a drug can deliver a clear benefit with minimal risk, no one should expect a bumper crop of new diet drugs anytime soon.