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On
May 7th, Forest Laboratories
reported a bit of bad news and its share price dipped to $51. The
company said in clinical trials, memantine did not prove to be
effective against neuropathic pain in diabetic patients. The
study failed to demonstrate a statistically significant difference
versus placebo treatment. Little details were given on the trial
except Forest Labs said it is reviewing the data to decide
whether, and how, the company can develop memantine for
neuropathic pain, because earlier trials had suggested the drug
memantine might be effective.
Neurobiological Technologies (Nasdaq:
NTII) along with Forest Labs is developing memantine for
neuropathic pain.
In our opinion, the news is a minor
set back for Forest Labs as most analysts did not expect memantine
to receive FDA approval to treat neuropathic pain. The driver for
memantine will be in the treatment for Alzheimer’s disease. As a
reminder, the NDA for memantine was filed with the FDA on August
1, 2002, but Forest Labs withdrew its filing, as additional
clinical trial results were becoming available. The FDA accepted
the second filing for memantine in January 2003 and Forest is
expecting to receive an initial action letter from the FDA by
October 2003. Should the FDA find Forest’s application
acceptable, memantine could be granted approval in late 2003 or
early 2004.
Forest is presently conducting
three additional placebo-controlled Phase III studies in
mild-to-moderate and moderate-to severe Alzheimer’s. Recently,
the company released data from the first of these three trials
demonstrating no pharmacokinetic drug interactions between
memantine and aricept.
Management
appeared very confident that it has the appropriate data to get
this drug approved.
In a six-month Phase III,
double-blind, placebo-controlled trial with 400 patients that had
moderate to severe Alzheimer’s disease, patients were treated
with memantine or placebo in addition to their regular dose of
aricept. At the completion of the trial, patients in the memantine
plus aricept group had superior improvements in scores of
cognition and behavior compared to the group that received aricept
and placebo. These differences were statistically significant. The
results of this study were submitted to the FDA in December 2002.
This trial provides interesting
insight into the potential for improved outcomes for Alzheimer’s
patients. Current medications used to treat Alzheimer’s are
acetylcholinesterase (ACh) inhibitors and these merely provide
relief of the symptoms of Azlheimer’s and are far from a cure.
Any therapy that demonstrates an improvement in cognition will
have important advantages over the ACh inhibitors, which merely
slow the progression of the disease.
Memantine represents a novel
approach to treat Alzheimer’s disease in that no drug currently
available acts on the N-methyl-D-aspartate (NMDA) receptor and
none are indicated for the treatment of the advanced form of the
disease. The NMDA receptor binds the neurotransmitter glutamate,
which is generally believed to be the most important excitatory
transmitter in the brain.
With Alzheimer’s disease as
memantine’s target it is no wonder Forest Labs and analysts are
not worried about neuropathic pain. We think Forest has a winner
with memantine.
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