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Press Release:
http://www.uky.edu/PR/News/050217_parkinsons_treatment.htm

Researchers : Treatment Study Should Go On

Contact: Allison Elliott

In the wake of Amgen’s latest denial, researchers and patients are
seeking a third-party sponsor to provide the drug to the patients who
already have undergone surgery for GDNF delivery to the brain and want to
continue treatment. The Kentucky research team asks Amgen not to block
progress on treating Parkinson’s disease.


 LEXINGTON, Ky. (Feb. 17, 2005) -- In a recently published study,
University of Kentucky researchers say a promising experimental drug
actually appears to slow the progress of Parkinson’s disease, unlike
current treatments that only treat the debilitating disease’s symptoms.

The progress shown in an early clinical trial of glial cell line-derived
neurotrophic factor (GDNF) is why the decision by the drug’s maker –
Amgen – to halt testing is so disappointing, UK researchers and patients
who have been taking the drug contended in a news conference today.

“We are very disappointed by Amgen’s decision,” said Don Gash, the UK
Alumni Chair in Anatomy and Neurobiology, professor in the Department of
Anatomy and Neurobiology, and director of the M. Margrite Davis-Ralph E.
Mills Magnetic Resonance Imaging and Spectroscopy Center at UK.
“Parkinson’s is a debilitating disease, and the patients and families who
have staked their hopes and lives on the testing of this treatment
deserve better.”

However, Amgen’s decision to deny compassionate use, announced Feb. 11,
2005, leaves patients cut off from the drug they say they need. In its
decision, the pharmaceutical company cited safety and efficacy concerns,
but their data are based upon tests utilizing animal models and dosing
procedures that differ from the successful UK study, contend Gash and
fellow researcher Greg Gerhardt. Gerhardt is a professor in the
Department of Anatomy and Neurobiology and Department of Neurology,
director of the UK Morris K. Udall Parkinson’s Disease Research Center of
Excellence, and director of the Center for Sensor Technology.

In the Journal of Neurosurgery, UK researchers report that their open
label study of direct brain delivery of GDNF, a natural brain protein,
demonstrates the safety and potential efficacy of the procedure.

According to Gash, the best hope for the Kentucky patients to resume
receiving GDNF lies in the possibility of sponsorship of Phase 2 clinical
trials by a third party. UK was one of several international sites
testing GDNF.

Researchers who oversaw the various successful human trials of the drug
first joined together in a request for compassionate use of the drug by
those patients whose lives had already been improved by GDNF. Though the
FDA supported their case, Amgen did not.

In the wake of Amgen’s latest denial, researchers and patients are
seeking a third-party sponsor to provide the drug to the patients who
already have undergone surgery for GDNF delivery to the brain and want to
continue treatment. The Kentucky research team asks Amgen not to block
progress on treating Parkinson’s disease.

“For science to advance, it is very important to continue studying the
patients who chose to resume GDNF treatment,” said Gash.

The University of Kentucky study expands upon an initial report on GDNF
authored by neurosurgeon Dr. Steven Gill and colleagues at the Frenchay
Hospital in Bristol, United Kingdom. The six-month Kentucky study was an
FDA-approved, Phase 1 trial of 10 patients with advanced Parkinson’s
disease. The Kentucky patients were the first in the United States to
receive direct brain delivery of GDNF.

The drug was delivered directly to patients’ brains via implanted pumps.
Patients received a fixed daily dose, increased at successive eight-week
intervals, followed by a five-week “washout” period during which GDNF was
not administered.

The results were positive. Patients who were unable to complete simple
tasks before receiving GDNF experienced substantial improvements in motor
skills and physical function during treatment. Twenty-four weeks after
beginning GDNF administration, patients’ scores on the Unified
Parkinson’s Disease Rating Scale (UPDRS) – the standard clinical measure
of Parkinson’s – improved 34 percent in the “off” and 29 percent in the
“on” state, compared to a baseline measured before GDNF treatment.

Although patients received GDNF to only one side of their brains,
measures using standard neurological tests showed improvements of 40 to
50 percent in fine motor control and speed on both sides of their bodies,
along with improvements in posture stability and gait. All improvements
of motor function continued through washout. The only side effect,
reported by two of the patients, was a mild tingling sensation known as
transient Lhermitte’s sign.

“GDNF appears to slow the loss of dopamine cells in the brain – a key
factor in stemming the progression of Parkinson’s disease,” said Dr. John
Slevin, professor in the UK Department of Neurology and Department of
Pharmacology and director of the Movement Disorders Clinic at UK. Slevin
said, “Amgen contends current treatments are therapeutically equivalent
to GDNF, but the drugs now available lose efficacy as the disease
progresses, and do little to slow the loss of dopamine cells.”

One reason cited by Amgen for the withdrawal of GDNF was the observation
of cerebellar lesions when large doses of GDNF were used in an animal
model.

“None of the patients have shown evidence of cerebellar injury; it has
only been seen in animals. To understand what has happened, we are
increasing our testing of potential adverse effects of GDNF,” Gerhardt
said. “These toxicity results should be taken very seriously. However, we
need to push forward and examine whether the negative results are
specific to animals. Further testing is warranted.”

On Aug. 31, 2004, at the conclusion of the successful Phase 1 trial at
UK, patients decided to continue receiving GDNF as part of a Phase 2
clinical trial sponsored by Amgen. The next day the drug manufacturer
announced they would discontinue all testing. The patients, who met each
other for the first time when they agreed to join the Phase 2 trial, have
joined with patients from other test sites in asking for continued use of
the drug they say improved their lives.

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