High Risks, Bottom Lines
In 2002, announcing a "war on Alzheimer's disease," Wyeth CEO Robert Essner said, "This is going to be the disease—and maybe
one of the biggest healthcare political issues—of my generation." More than 5 million Americans are afflicted, and nearly
10 million are unpaid caregivers, according to the Alzheimer's Association. The annual cost of the disease is already $150
billion, and over the next decade, as Baby Boomers swarm the Medicare rolls and the incidence of AD rises 30 percent, a crisis
is in the offing.
For pharma, every crisis is an opportunity. "The barrier to entry is not very high," says Datamonitor CNS senior analyst Terence
McManus. "Any drug that is disease-modifying will be an instant blockbuster." Yet the brain remains something of a mystery,
and AD research presents a minefield—poor biomarkers and animal models, and clinical trials that are among the longest, largest,
and costliest in the industry. Humans appear to be the only animal to suffer from this slow-to-develop, late-to-diagnose neurodegenerative
process, so drugmakers with a promising—but dimly understood—compound have to choose between shelving it or going headlong
into Phase III. With risks like those, scientific orthodoxy at least provides cover for pharma managers.
B-mab is the big weapon in Essner's war. Working with Dublin-based Elan, Wyeth developed the compound by reverse-engineering
their failed experimental AD vaccine and injecting pre-made amyloid-protein antibodies directly into patients. Currently in
Phase III, b-mab is expected to face FDA in early 2011. Though its data have underwhelmed, J&J liked it enough to pay $1.5
billion for a small stake in Elan and a big share of b-mab sales, which McManus estimates to peak at $2.8 billion in 2018.
B-mab's early hype sent other drugmakers searching for their own anti-amyloid monoclonal antibodies. Lilly's solanezumab is
the only competitor to have advanced into Phase III—and that by skipping a Phase II efficacy trial. The company also rushed
its novel gamma-secretase inhibitor, semagacestat, which turns off amyloid production, into Phase III. Baxter International's
Gammagard, an immune-globulin cocktail for leukemia that also has anti-amyloid antibodies, is due to report Phase III results
Each of these compounds binds to amyloid in a unique way. But none appears to halt, let alone reverse, the relentless progression
of AD. How they'll fare at FDA is a great unknown. But one thing is certain: Pressure from patients and caregivers for treatments
that offer even incremental improvements will be intense.
What's the Alternative?
With so much focus on b-mab, an the old Russian antihistamine revamped by Medivation to treat AD flew under the radar. Yet
dimebon has emerged, however unexpectedly, as the best hope of mastering the Alzheimer's beast. "It's the only drug in the
history of Alzheimer's where there was actual clinical improvement on all five outcome measures, and these benefits increased
substantially at week 52 compared to week 26," says McManus. The chemical's neuroprotective power remains a bit obscure, but
it appears to modulate several neurotransmitters—improving AD's symptoms—while also hitting the mitochondria, which confers
its disease-modifying potential. (Mitochondria, cells' "power plants," are central to many critical cell functions, and may
spark brain-cell death by the production of free radicals.) Pfizer is partnering with Medivation in five Phase III trials
in a deal worth up to $725 million in milestones; the drug is being tested in all stages of the disease. If these data are
consistent with earlier results, dimebon looks destined for FDA approval. Yet proving that dimebon is truly disease-modifying
will be an uphill battle. "Clinical trials don't last long enough to confirm reversal, and the mechanism of action has yet
to be clearly defined," says McManus, who projects that dimebon will become the first-line treatment with peak sales of $5
billion in 2018.
Claude Wischik is also working the mitochondria angle at his biotech, TauRx. He argues that tau tangles, not amyloid clumps,
are central to AD's neurotoxic cascade, which is set in motion by mitochondria whose finely tuned programming goes haywire
with aging. TauRx's lead product is Rember, a formulation of MTC, the reagent methylene blue. According to Wischik, it prevents
tau protein aggregation by boosting production of a mitochondrial enzyme. In Phase IIb trials, the startup reported—albeit
in a rushed fashion that sparked controversy—significant improvement at 24 weeks and stabilized AD over 50 weeks. Meantime,
Ashley Bush's metals-ion has moved from marginal to mainstream. His hypothesis is that aging wreaks havoc on the body's delicate
balance of metal ions: Zinc causes amyloid to accumulate, and copper bound to amyloid peptides catalyzes oxidative damage.
The technology he and his colleagues developed at Prana Biotechnology—called metal-protein attenuating compound—has yielded
four AD candidates, including a lead compound in Phase IIa. An analog of the antifungal clioquinol, PBT2 acts as a chaperone
for zinc and copper, blocking oxidative neurodegeneration and preventing toxic amyloid accumulation. (The next discovery required
of both Bush and Wischik is a deep-pockets partner to launch large-scale trials.)
With some 600 other compounds in the AD pipeline, Khachaturian's fears of a mass exodus by pharma may be exaggerated. Still,
the AD veteran is preparing a contingency plan. "We have to adopt strategic partnership models where risk, cost, and revenues
are shared among industry, academia, and government," he says. His "Campaign to Prevent Alzheimer's Disease by 2020" is organizing
think tanks to explore options, including virtual research to bridge the drug discovery/development gap, collaborative projects,
and sharing of novel ideas. "But intellectual property issues that restrict progress need reform," he says. That's one paradigm
shift, however, that may make pharma take flight.
Next-Gen Azheimer's Drugs