Obesity: The 10 Percent Rule
The legacy of fen-phen's and accomplia's disastrous side effects casts a long shadow over the dream of a pill that melts away
fat. This year has been especially dark for obesity drugs: one standby was yanked from the market and last month, Arena's
lorcaserin and Vivus' Qnexa each went before the FDA advisory firing squad only to have their one-year Phase III data shot down. In both cases, the FDA
asked for two-year trials—to allow for a more realistic amplification of any potential safety signals, especially given the
fact that obesity drugs, however narrowly indicated, have a curious tendency to become mass-market products. "At the FDA meetings,
the body language of the committee was worse for lorcaserin than for Qnexa," says Alan Carr, a Needham & Co. analyst.
Qnexa takers in Phase III trials lost an average of 10 percent of their body weight—twice the minimum FDA requirement. Average
pounds dropped by people on Orexigen's Contrave, which has its day in the FDA sun this month, was 5 percent. Lorcaserin failed to hit even that mark. Most analysts expect
lack of efficacy to combine with an abundance of adverse-events risk to sink all three agents. But Ben Weintraub, director
of research at Wolters Kluwer Pharma Solutions, begs to differ, spying a sunny sky for both Contrave and, especially, Qnexa.
"Losing 10 percent of body weight is a significant accomplishment, and additional safety data will likely satisfy the FDA's
concerns," he says. The drugs may be tightly restricted to obese people with cardiovascular problems who face an early death.
But three strikeouts would mark the start of a long and silent post-season in the weight-loss field. "It will be years before
we see another obesity drug," says Carr.
Alzheimer's: A Disease at a Crossroads
"Alzheimer's is the black hole of R&D," says Wolters Kluwer's Ben Weintraub. "It's the only big disease left that is basically
untreatable." Since 2003, more than 10 much-hyped compounds have bitten the dust. Almost all targeted the protein amyloid-beta,
the hallmark plaque long thought to cause the disease's devastation of brain matter. But experimental agents that slow or
stop the amyloid buildup have stubbornly shown no cognitive or memory benefit in patients. Last summer, the amyloid hypothesis
hit a crisis point when a Phase III Lilly drug was shown to do a great job removing the plaque—only to result in a negative
clinical effect. Two top Harvard Alzheimer's experts published a paper promoting the inevitable, if heretical, hypothesis:
Does amyloid protect rather then destroy neurons?
Ben Weintraub, Director of Research, Wolters Kluwer Pharma Solutions
There is a growing consensus that by the time amyloid buildup is detectable, the disease has likely progressed too far to
be modified. Effective treatment must begin much earlier, but so far no biomarker has been discovered to identify vulnerable
patients. And with the association between surrogate markers and clinical benefits increasingly in doubt, the FDA is currently
at a loss when it comes to evaluating the efficacy of new drugs. Drugmakers are understandably discouraged at the prospect
of progressing yet another risky molecule, given the fact that Phase III Alzheimer's trials are among the longest, hardest,
and most expensive in pharma R&D. "Companies are forced to do proof-of-concept in Phase III because Phase II trials are too
small and there are no acceptable animal models," says Alan Carr.
Bapineuzumab (bapi), a monoclonal antibody developed by Elan and Wyeth (now J&J and Pfizer), may win FDA approval by sheer dint of its
drugmakers' refusal to shelve it. A passive immunotherapy that triggers amyloid antibodies, bapi reduced plaques by 25 percent
but flunked midstage efficacy tests—except in a subset of patients who lacked a specific mutation. The determined J&J/Pfizer
group has launched 14 Phase III trials with a total of 10,000 patients. Recently, researchers made the intriguing finding
that bapi may show some clinical benefits because of an indirect downstream effect: it appears to lower the amount of tau,
Alzheimer's No. 2 surrogate marker, in spinal fluid.
Despite its recent setback, Lilly is full steam ahead with its Alzheimer's program, one of the industry's largest. Its new
lead product is a second amyloid-targeting Phase III compound, solanezumab, a monoclonal antibody that sucks up amyloid before it can form plaque deposits.
EnVivo Pharmaceuticals is testing EVP-6124, a partial a7 nicotinic receptor agonist that appears to stimulate neurons, increasing the alertness effect of the neurotransmitter
acetylcholine. If this effect pans out, EVP-6124 may be given in tandem with current cholinesterase inhibitors, which increases
levels of acetylcholine, potentially allowing for lower doses and fewer side effects.
The outlier in the late-stage pipeline is Baxter's Gammagard, an IV immunoglobulin containing amyloid-beta antibodies, which emerged as an Alzheimer's contender after a retrospective
analysis revealed that people previously treated with the passive immune therapy had 42 percent less risk of developing the
disease. A Phase II study showed significant benefits in three measures—cognitive, functional, and neuroimaging—a first for
any Alzheimer's trial. Two Phase III trials are ongoing.
Meantime, the need for new drugs intensifies as more and more Baby Boomers live into advanced old age. The global market is
estimated to be worth $20 billion by the end of the decade. "This is a time of major soul-searching in the field," says Dr.
Murali Doraiswamy, an Alzheimer's researcher at Duke University.