12.2019 | THE SCIENTIST 27© SCIENCE SOURCE, CMUH
I
n September of this year, pharmaceutical
companies Biogen and Eisai announced
that they were halting Phase 3 clinical trials
of a drug, elenbecestat, aimed at thwarting
amyloid-β buildup in Alzheimer’s disease.
Although the drug had seemed so promising
that the companies elected to test it in two
Phase 3 trials simultaneously, preliminary
analyses determined that elenbecestat’s
risks outweighed its benefits, and the drug
shouldn’t be moved to market. The cancel-
lation “amounts to a further step in the
unwinding of Biogen’s expensive, painful, and
ultimately fruitless investment in Alzheimer’sdisease (AD) drug development,” analyst
Geoffrey Porges told Reuters at the time.
Biogen’s misfortune is just the latest in
a slew of late-stage Alzheimer’s drug fail-
ures. Six months earlier, the company had
halted another set of parallel Phase 3 tri-
als due to lack of efficacy of a different drug
candidate, aducanumab (though after fur-
ther data analysis, Biogen announced that it
will seek approval for aducanumab after all).
And between 2013 and 2018, Pfizer, Eli Lilly,
Merck, and Johnson & Johnson all termi-
nated Phase 3 or Phase 2/3 trials due to poor
early results. Ye t some Alzheimer’s research-ers say they think they’ve spotted a silver lin-
ing in this cloud of bad news—a hint in the
data from these studies about how future
work might meet with more success.
In some of these trials, Alzheimer’s
patients who were at earlier stages of the
disease did better than those with more
advanced cognitive decline, says Colin Mas-
ters, a neuroscientist at Florey Institute of
Neuroscience and Mental Health in Australia
who was not involved in the trials. This indi-
cates that the key to finding an effective treat-
ment might be to catch subjects before their
condition advances too far, he adds. “The idea