The atmosphere in the packed San Diego Huntington’s disease
support group meeting room on the evening of October 28 was both somber and
electric with anticipation.
Flanked by loved ones, HD-affected individuals struggled
with involuntary movements and a hampered ability to communicate, providing
stark evidence of the disease’s unrelenting attack on minds and bodies.
For asymptomatic HD gene carriers like me, they represented
our future if scientists don’t soon find a way to stop the inevitable,
devastating symptoms. I always leave these monthly meetings deeply unsettled and
unable to sleep soundly.
At the front of the room, a key player in the effort to
develop effective treatments, Jody Corey-Bloom, M.D., Ph.D., explained how the
local firm Isis Pharmaceuticals, Inc., had successfully run the first
ever safety test of its unique type of drug in patients suffering from a
neurological disorder, in this case, amytrophic lateral sclerosis (ALS), also
known as Lou Gehrig’s disease or motor neuron disease. The results were
published in the May 2013 issue of the journal Lancet Neurology.
Isis is developing an HD-gene-silencing drug in partnership with the
pharmaceutical giant Roche.
“I realize you guys are just tired of waiting (for
treatments),” Dr. Corey-Bloom told the audience of some 50 people. “But I think
Isis is really in a good position right now (to get their HD drug into a
clinical trial)…. They’ve got lots of money, with Roche’s kind of support. I
think that they’re feeling comfortable about the fact that they were able to do
this.”
None of the ALS trial participants experienced adverse
effects from the Isis drug, Dr. Corey-Bloom said.
Although Dr. Corey-Bloom pointed out that the very small dose of
the Isis drug, an artificial form of DNA known as an antisense oligonucleotide
(ASO), did not affect the ALS symptoms, the evidence from the trial of safety
and patients’ tolerance for the drug helped paved the way for additional tests
to examine efficacy.
It also set the stage for the planned Isis-Roche HD clinical
trial, tentatively scheduled to start sometime in the next 18 months. The
project has the support of the CHDI Foundation, Inc., the non-profit virtual
biotech firm dedicated to finding treatments for HD. (Click here to read more.)
Surveying the field
The San Diego support group had convened to hear Dr. Corey-Bloom’s
annual HD research update, usually the best attended meeting of the year.
The diminutive but tireless neurologist dedicated the first
half of her 85-minute presentation to HD research conducted locally, including
projects at the unit she directs, the Huntington’s Disease Society of America
Center of Excellence for Family Services and Research at the University of
California, San Diego. These studies have mainly focused on ways to measure the
onset and progression of the disease – essential for gauging the efficacy of
drugs tested in clinical trials. (Click here for an example.)
In addition, Dr. Corey-Bloom surveyed some of the clinical
trials set to begin soon, including a phase II trial for a phosphodiesterase
inhibitor (a kind of “Viagra for the brain”) planned by Omeros Corporation.
Dr. Corey-Bloom also announced that she’s seeking funding from
the National Institutes of Health (NIH) to conduct a clinical trial in HD
patients of an already widely used non-HD drug shown to increase BDNF (brain
derived neurotrophic factor), a kind of “fertilizer” for the brain. HD patients
have insufficient BDNF, which could cause cell death in the deep structures of
the brain where the disease is thought to begin, she explained.
“I stumbled across it mainly because I was just reading some
other things,” said Dr. Corey-Bloom, who declined to identify the drug until
funding is in place and the drug’s manufacturer agrees to participate in the
research. “I said, ‘Ooh! Wow!’ It’s such a great story. It’s been keeping me up
at night thinking about it. We will
get it going. First with animals, then with people.”
Her project collaborator is Beth Thomas, Ph.D., of the Scripps Research Institute in San Diego.
You can watch Dr. Corey-Bloom’s presentation and the Q &
A in the videos below.
Advances in Huntington's Disease Treatments: A Presentation by Dr. Jody Corey-Bloom (Part I) from Gene Veritas on Vimeo.
Advances in Huntington's Disease Treatments: A Presentation by Dr. Jody Corey-Bloom (Part II) from Gene Veritas on Vimeo.
Comfort and risk
versus efficacy
As potentially one of the best treatments for HD because of
its genetic approach, the Isis ASOs for HD commanded the most attention from
both Dr. Corey-Bloom and the audience.
As Isis and Roche move ever closer to the long-awaited trial
– Isis had first hoped to start a Phase I several years ago – crucial questions
of drug delivery and dosage have gained increasing attention.
Dr. Corey-Bloom’s observations highlighted a delicate issue:
the tensions between patient comfort/risk and drug efficacy.
She identified a key question: will enough of the ASO
travel through the cerebral spinal fluid (CSF) from the patient’s back, where
Isis plans to introduce the drug via a spinal tap, all the way to the brain?
A certain amount of the CSF naturally travels up the spinal
column and over the brain, Dr. Corey-Bloom explained, but some of the ASO
medication could be lost along the way.
“I think one of the big issues is how to inject,” she said.
“I actually said the last time I was at Isis that they just need to put in an
Ommaya reservoir and just inject it that way…. We do lots of chemotherapy for people that have
brain cancer or brain infections. We put this little plastic disk into this
space at the bottom of the brain [she indicated behind her ear], and then if
people need to have anti-fungal medication … or cancer chemotherapies, we
inject right into that little bubble, and it goes right into the cerebral
spinal fluid.”
Dr. Corey-Bloom said that Isis scientists wanted to avoid
the extra risk and cost of the Ommaya insertion, which, although done in just
about 15 minutes and with minimal sedation, requires an operating room.
“It’s so much easier to be doing it through a spinal tap in
the back than to be doing ‘brain surgery,’ which is what they kept calling it,”
she continued, referring to the fact that the spinal tap doesn’t require an
operation.
However, she affirmed that opting for the “more involved”
Ommaya reservoir could bring better trial results.
“At least we’ll know that the medicine is getting in right
up there, as opposed to way down here,” she said, pointing to her back. “If it
doesn’t work, or if it doesn’t work as well as it should, we’ll be kind of
wondering if maybe should have put it in a lot closer to where we need it to
go.”
Proactive families
The support group/physician connection underscores the
critical role of proactive patient and family participation in research and
clinical trials.
The audience always follows up with questions that focus on
the heart of the matter: when and how clinical trials and treatments will bring
the promise of ameliorating HD.
Referring to Dr. Corey-Bloom’s discussion of the critical
use of MRI scans in HD research, one group member asked whether a similar
magnetic force or some electronic structure could be used to “drive” the Isis
ASO drug up to the brain.
That’s “really kind of clever,” she responded, noting that
she would present the idea to Isis when she meets with company researchers on
November 20 to discuss the clinical trial program, including the option of the
Ommaya reservoir. Her job, she said, is to bring home the clinical reality of
HD to scientists who spend most of their time in the lab.
Future benefits
Dr. Corey-Bloom also will urge Isis to go beyond the
standard safety and tolerability measures of a Phase I trial to consider measuring
efficacy, too, she added. “They’re going to want to do a Phase I trial that is
only safety and tolerability…. I think that misses your opportunity to do
exploratory efficacy measures.”
The Food and Drug Administration permits this type of
exploratory work in Phase I, she noted.
Isis and Roche could not draw official conclusions from such
exploratory data, she said, but it could give the scientists “some idea of what
to use” in the potential Phases II and III of the trial and beyond.
Looking to the future could help broaden the application of
the drug to people in different stages of HD – including presymptomatic gene
carriers like me for whom an effective treatment would prevent onset and
ultimately make HD a thing of the past.