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Science Forum Index » Medicine - Cancer Forum » The Anti-Smoking Vaccine
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| E.Nigma |
 Posted: Fri Dec 15, 2006 1:54 pm |
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By Jeffrey Helm, The Tyee
First Posted on September 30, 2006,
http://www.alternet.org/story/41848/
Someday, along with jabs against mumps and measles, kids could get
vaccinated against nicotine, cocaine and heroin.
Vaccines for cocaine and nicotine have already been tested in humans.
Nicotine vaccines, in particular, are getting a lot of attention.
This summer a recruitment campaign got under way across the United
States for clinical trials of NicVAX, a nicotine vaccine. Nabi
Pharmaceuticals says it is developing NicVAX in order to help
"billions worldwide who are addicted to smoking tobacco products or
are at risk of becoming addicted."
But vaccines against a drug are different from normal vaccines
against disease-causing viruses and bacteria. Normal vaccines prevent
disease from taking hold. That is not the focus of drug vaccines like
NicVAX.
"The target for [drug] vaccines right now is treatment or relapse
prevention," says Dr. Paul Pentel from the University of Minnesota,
one of the leading researchers in nicotine vaccine development. "It's
simply way to early to know if vaccines would be appropriate for
[addiction] prevention."
Even so, that won't prevent the off-label use of a product like
NicVAX. Off-label use is when doctors prescribe a drug for something
other than what it was originally meant for, and for some drugs,
off-label use accounts for the bulk of their sales.
Whether the purpose is treatment or prevention, a vaccine made
against a drug would soak up the drug and prevent it from working.
Even if a smoker who was trying to quit slipped and lit up, the
cigarette would just tar up their lungs a little more. No buzz, just
stinky hot smoke. An effective nicotine vaccine would force you to
quit cold turkey whether you wanted to or not. Which is both a
strength and a potential problem of such treatments.
How an anti-drug vaccine works
Vaccines work by getting your body to produce antibodies, which are
molecules designed to bind. They are tailor-made to latch onto and
immobilize anything foreign that catches the attention of your immune
system. Antibodies are also very specific. An antibody against a
virus, like polio, won't work against anything else.
Normally the body does not make antibodies that target drugs because
drug molecules are too small. They need to be small so that they can
move easily from the blood to where they work in the brain.
In order for the immune system to make antibodies against a drug, a
piece of the drug molecule is joined to a larger protein that the
immune system will pay attention to. Then the body will start making
antibodies that will grapple onto the drug.
With a standard immune response, other cells chew up bound
antibodies, and whatever they are hanging onto. This does not happen
with vaccines for drugs; the antibodies just stay latched to the drug
molecules. But now the drug molecule is much bigger since it has an
antibody stuck to it. So big, that the bound drug can't get into the
brain to do any harm. Neither can it interact with anything else in
the body.
A few party crashers help withdrawal
The intended use of NicVAX, and other drug vaccines in development,
is to help people quit and stay clean.
In a small preliminary study, 40 per cent of smokers on NicVAX quit,
as compared to a 9 per cent quit rate of those on a placebo (fake
drug). "That differential was the largest differential of any smoking
cessation product ever tested," Tom Rathjen, vice-president of
investor relations for Nabi Biopharmaceuticals, said.
Great results, even when some of the nicotine is getting to the
brain.
Shutting out the drug completely from the brain was the initial idea,
but the antibodies made from NicVAX let a little nicotine through --
which actually isn't so bad. The small amount of nicotine that gets
through lessens withdrawal symptoms, and for reasons that are not
entirely clear, the entry of unbound nicotine into the brain is also
slowed. This slowing of nicotine entry also reduces its addictive
strength.
"The reinforcing properties of nicotine are greatest in the first few
seconds or minutes after a puff of a cigarette," Pentel said. "If
it's possible to slow the entry of nicotine into the brain, this
could potentially reduce its subjective and its addictive effects."
But I don't like needles
Physicians have concerns with drug vaccines, like NicVAX, beyond
possible allergic reactions that come with any vaccine. With a
vaccine against a drug, whenever the drug is taken, bunches of
antibody-drug formations fill the blood stream. When more than one
antibody binds to a drug, the resulting clump, called an
antigen-antibody complex, can cause problems. Dr. David Marsh, who is
the head of Addiction Services for Vancouver Coastal Health,
expressed concern that drug vaccine studies have not always looked at
antigen-antibody complex effects because they are difficult to study.
"I'm not sure if the trials to date have addressed the potential
risks of that, like glomerular nephritis (kidney problems), or other
problems that antigen-antibody complexes are known to cause."
Although antigen-antibody complexes may still be a concern for other
drug vaccines in development, for NicVAX it doesn't appear to be a
problem. The antibodies produced with NicVAX bind nicotine
one-to-one, so no antigen-antibody complexes would be formed that
could damage the kidney. Another concern, and potential benefit,
would be the longevity of the treatment. Some traditional vaccines
against disease can give you immunity for life -- immunity that you
cannot reverse. A lifelong effect is much more economical than a
regime of pills, but, as a general rule, non-reversible treatments
make doctors nervous. If something goes wrong, you cannot stop the
treatment. Although NicVAX does last a long time, the effects are not
lifelong, so the treatment should be reversible in time. Preliminary
studies have shown that a treatment of NicVAX lasts for 12-18 months.
No more 'just say no'
The biggest controversy around drug vaccines is the possibility that
the technology could be used to immunize people against drug use
before they become addicted. Researchers say that it is much too
early to even begin thinking about using vaccines for addiction
prevention. But market forces being what they are, researchers don't
have much say.
NicVAX is being fast-tracked for approval by the Food and Drug
Administration (FDA) of the United States, and if everything goes
well, it could be on the market by late 2008.
Once NicVAX is on the shelves, there is nothing preventing doctors
from prescribing it for the troubled child of parents worried that
their offspring might pick up bad habits after school. Nabi
recognizes that this off-label use of NicVAX could occur and is
careful not to make any rash judgements. "That [preventative use]
obviously becomes a controversial issue with many people," says
Rathjen. "It would not be something that we are going to be pursuing,
at least initially." But not all off-label use of NicVAX is as
ethically questionable as childhood vaccinations.
Less controversial would be vaccinating pregnant mothers to protect
developing children from the negative effects of their mother's drug
use. Nabi is leaving their options open, but vaccinations in the
interest of healthy babies aside, the debate on drug vaccines for
addiction prevention might be closed before the ethical arguments
even start. This is because drug vaccines don't provide absolute
immunity. Especially for people who don't want to be immune.
The amount of antibodies that are produced in response to a vaccine
are not limitless. Thus, if someone really wants to get high, they
will just take more of the drug in order to overwhelm the antibodies
in their system. But the amount of drug that would be needed to
overwhelm the antibodies would be very high and dangerous to take,
since it could very easily lead to an overdose. In the case of
NicVAX, you'd have to smoke a whole lot of cigarettes. Rathjen said
that NicVAX "was effective in animals that were given the equivalent
of 20 packs of cigarettes a day."
Previous research also shows that people and animals don't take more
of a drug in an effort to overwhelm the antibodies. But it is
unlikely that the animals knew they could overwhelm the antibodies
with more drug, and people that sign up to test a drug vaccine
probably have at least a small desire to quit. "Vaccines [for
addiction], like other medications, have to be used in appropriate
populations," says Pentel. That population being people who want to
stop using and abusing addictive drugs.
For overdoses, antibodies made to order
With vaccines it often takes time, and sometimes more than one
injection, before there are enough antibodies in the body to get
anything done. It takes around four injections of NicVAX over two
months to get functional antibody levels. But in critical situations,
like a drug overdose, you only have minutes, not months. The body
needs time to make antibodies, but antibodies can be pre-made and
injected into the bloodstream, which would be a useful tool for
doctors. "If somebody arrives at the emergency room with an overdose,
you could infuse them with a packet of antibodies and soak up the
drug," explains Dr. Marsh. Pre-made drug antibodies would also have
less safety concerns than vaccines because they wouldn't stay in the
body as long. Where pre-made antibodies would be most beneficial is
for other abused drugs besides nicotine.
Currently there is vaccine and antibody research being done for
cocaine, heroin/morphine, methamphetamine, and phencyclidine (PCP).
======
E.
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| J |
| Posted: Fri Dec 15, 2006 3:06 pm |
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betsyb wrote:
Quote: "E.Nigma" <NoReply@vnn.vn> wrote in message
http://www.alternet.org/story/41848/
Someday, along with jabs against mumps and measles, kids could get
vaccinated against nicotine, cocaine and heroin.
Vaccines for cocaine and nicotine have already been tested in humans.
Nicotine vaccines, in particular, are getting a lot of attention.
This summer a recruitment campaign got under way across the United
States for clinical trials of NicVAX, a nicotine vaccine.
Do everyone a favor and post where we can find the Clinical Trials?
This Phase II is no longer recruiting
http://clinicaltrials.gov/show/NCT00218413
This one is.
http://clinicaltrials.gov/ct/show/NCT00318383
Phase IIB results (expected) to be released mid 2007
http://www.nabi.com/images/factsheets/fsNicVAX.pdf
The study protocol is based on consultations with U.S. and EU regulators on
the design and endpoints for Phase lll efficacy studies. Results from this
study are expected to be announced in mid-2007. The timing of this study
positions the company to be able to initiate Phase lll efficacy studies in
the second-half of 2007.
J |
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| betsyb |
| Posted: Fri Dec 15, 2006 3:31 pm |
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"J" <ercent@anon.inv> wrote in message
news:4582F24F.613A9E96@execulink.com...
Quote: betsyb wrote:
"E.Nigma" <NoReply@vnn.vn> wrote in message
http://www.alternet.org/story/41848/
Someday, along with jabs against mumps and measles, kids could get
vaccinated against nicotine, cocaine and heroin.
Vaccines for cocaine and nicotine have already been tested in humans.
Nicotine vaccines, in particular, are getting a lot of attention.
This summer a recruitment campaign got under way across the United
States for clinical trials of NicVAX, a nicotine vaccine.
Do everyone a favor and post where we can find the Clinical Trials?
This Phase II is no longer recruiting
http://clinicaltrials.gov/show/NCT00218413
This one is.
http://clinicaltrials.gov/ct/show/NCT00318383
Phase IIB results (expected) to be released mid 2007
http://www.nabi.com/images/factsheets/fsNicVAX.pdf
The study protocol is based on consultations with U.S. and EU regulators
on
the design and endpoints for Phase lll efficacy studies. Results from this
study are expected to be announced in mid-2007. The timing of this study
positions the company to be able to initiate Phase lll efficacy studies in
the second-half of 2007.
J
Thanks much J. One is by my son in Maryland and he also needs to stop. Too
bad there are none closer to NJ |
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