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Xenova Group plc (XEN)

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Wednesday 14 July, 2004

Xenova Group plc

Xenova Group plc - Research Update

Successful Results from Second Clinical Trial
of Anti-Smoking Vaccine, TA-NIC

Slough, UK, 14 July 2004 - Xenova Group plc (London Stock Exchange:
XEN; NASDAQ: XNVA) announced today initial results from the second
clinical trial of TA-NIC, the Company's therapeutic vaccine being
developed for the treatment of nicotine addiction.

60 smokers, divided into three cohorts of 20 subjects, have been
recruited into this double-blind, randomised, placebo-controlled
study.  The objectives of this second Phase I clinical study were to
explore the safety, tolerability and level of anti-nicotine antibody
response to increasing doses of the vaccine TA-NIC, and to select a
dose for Phase II/III evaluation.

Key findings from the study were:

*          No drug-related serious adverse events were seen in any
*          Minimal injection-site effects were seen at the dose
  selected for Phase II/III studies
*          Anti-nicotine antibody responses were dose dependent
*          The selected dose showed an improved anti-nicotine
  antibody response profile compared to the lowest dose tested:
o        Approximately twice the level of anti-nicotine antibodies
were observed
o        Faster and more rapid onset of anti-nicotine antibody
response was achieved
*          Although not designed to test the effect of the TA-NIC
  vaccine on smoker's quit rates, there was a clear reduction across
  all groups receiving TA-NIC compared to those with the placebo
  group, in terms of those smokers who voluntarily quit during the
  12-week period or self-reported a reduction in smoking pleasure
o        At week six, 19 out of the 44 (43%) subjects receiving
TA-NIC voluntarily gave up smoking or reported reduced pleasure when
smoking compared to only 1 out of 11 (9%) receiving the placebo
On the basis of these results, a Phase II/III dose has been selected
for further clinical evaluation.  The final data from this Phase I
study is expected at the end of this year (2004) with Phase II trials
commencing shortly thereafter.

David Oxlade, Chief Executive Officer of Xenova said, "We are most
encouraged by these results.  The next stage of trials will test
TA-NIC's ability to help smokers break the habit and thereby reduce
the serious consequences to health caused by smoking."

Xenova Group plc is a UK-based biopharmaceutical company focused on
the development of novel drugs to treat cancer and addiction with a
secondary focus in immunotherapy.  The Company has a broad pipeline
of products in clinical development, including three cancer
programmes:  its lead product TransMID(TM), for the treatment of
high-grade glioma, is in Phase III trials, and its novel DNA
targeting agents and XR303 are both in Phase I for cancer
indications.  Xenova is also developing two therapeutic vaccines for
cocaine and nicotine addiction, which are in Phase II and Phase I
trials respectively.  Quoted on the London Stock Exchange (XEN) and
on NASDAQ (XNVA), Xenova employs approximately 112 people throughout
its sites in the UK and North America. (Reuters XEN.L; Bloomberg XEN
For further information about Xenova and its products please visit
the Xenova website at

Notes to Editors

Clinical Data
The first Phase I placebo controlled clinical trial was completed in
60 smokers and non-smokers in June 2002.  The vaccine was well
tolerated locally and systemically up to a course of 5 vaccinations
of 50 mcg over 8-20 weeks and a booster vaccine given at 9 months
after the initial injection.  Nicotine-specific antibodies capable of
binding free nicotine were generated, unaffected by smoking status,
during the initial primary vaccination course.  These antibody levels
declined over 3-6 months, but a further significant increase in
antibody levels was seen rapidly after the single booster injection.

Smoking Statistics
The World Health Organisation (WHO) notes that the tobacco epidemic
is still expanding, especially in developing countries where
currently 84% of smokers live.  Tobacco use kills 4.9 million people
each year and this toll is expected to double in the next 20 years.
At current rates, the total number of tobacco users is expected to
rise to 1.7 billion by 2025 from 1.3 billion now (May 2004).

Smoking cessation in the UK
Long term (and short term) success rates in terms of smokers reducing
or stopping smoking remain low, with only approximately 5% of smokers
being able to stop smoking after receiving advice from their doctor;
a maximum of approximately 18% succeed when intensive support from
specialists as well as nicotine replacement therapy are provided in

Of the 1.3 billion smokers globally, it is estimated that some 4
million smokers each year in the UK attempt to quit, but that only
3-6% (or 1-2% of all smokers) are successful in giving up tobacco.
 Conventional treatment of nicotine addiction concentrates on
psychosocial interventions (counselling, smoking cessation clinics)
together with pharmacotherapy, including nicotine replacement therapy
(NRT) and bupropion (Zyban�, GlaxoSmithKline).  Even with effective
behavioural and pharmacological therapies, many individuals dependant
on nicotine fail in their attempts to remain abstinent, with smoking
cessation rates of only approximately 10-20% at 1 year.  Long term
cessation rates are even lower with 40% of ex-smokers relapsing after
12 months abstinence.

Inhaled nicotine is highly addictive.  Absorption of nicotine from
cigarette smoke through the lung is rapid, producing with each
inhalation a high concentration arterial bolus of nicotine that
reaches the brain within 10-16 seconds, faster than by intravenous
injection.  Nicotine is able to cross the blood brain barrier where
it binds to acetyl-choline receptors, triggering the release of
neurotransmitters, such as dopamine and serotonin.  These give rise
to positive feelings (pleasure, relaxation, lack of anxiety,
suppressed appetite, improved concentration) which are reinforced
with each cigarette.  Nicotine has a distribution half life of 15-20
minutes and a terminal half life in the blood of two hours. Smokers
therefore experience a pattern of repetitive and transient high blood
nicotine concentrations from each cigarette, with regular hourly
cigarettes needed to maintain raised concentrations, and overnight
blood levels dropping near to those of non-smokers.  Smoking
cessation is difficult to achieve due to the addictive properties of
nicotine and the unpleasant withdrawal symptoms (irritability, lack
of concentration, weight gain, nicotine craving).

TA-NIC mode of action
TA-NIC is a therapeutic vaccine in development for the treatment of
nicotine addiction.  Nicotine is a small molecule which, by itself,
does not trigger an immune response.  However, when nicotine is
carried by an immunogenic protein it can prime the immune system to
produce anti-nicotine antibodies.  The active ingredient of TA-NIC
vaccine is a protein conjugate: nicotine butyric acid (NBA)
covalently linked to recombinant cholera toxin B (rCTB).  rCTB was
chosen as the carrier protein because it is known to be highly
immunogenic and has been used for many years as a component of
cholera vaccine.  rCTB has been approved by the Swedish Medical
Products Agency for use in an oral cholera vaccine that is marketed
in Sweden and Norway and in 2003 was approved by the CPMP.

Nicotine is bound by the induced circulating anti-nicotine antibodies
in the bloodstream and the resulting antigen-antibody complex is too
large to cross the blood-brain barrier, so the pleasurable stimulus
which usually accompanies smoking will be absent or reduced. Without
this reward, the motivation to smoke again is reduced, preventing the
reinforcement which is required to maintain the nicotine addiction.

NICE Guidance on the use of nicotine replacement therapy (NRT) and
bupropion for smoking cessation. March 2002


For Xenova: Disclaimer to take advantage of the "Safe Harbor"
provisions of the US Private Securities Litigation Reform Act of
1995. This press release contains "forward-looking statements,"
including statements about development and commercialization of
products. Various risks may cause Xenova's actual results to differ
materially from those expressed or implied by the forward looking
statements, including: unexpected costs and delays, adverse results
in our drug discovery and clinical development programs; failure to
obtain patent protection for our discoveries; commercial limitations
imposed by patents owned or controlled by third parties; our
dependence upon strategic alliance partners to develop and
commercialize products and services; difficulties or delays in
obtaining regulatory approvals to market products and services
resulting from our development efforts; the requirement for
substantial funding to conduct research and development and to expand
commercialization activities; and product initiatives by
competitors.  For a further list and description of the risks and
uncertainties we face, see the reports we have filed with the
Securities and Exchange Commission.  We disclaim any intention or
obligation to update or revise any forward-looking statements,
whether as a result of new information, future events or otherwise.


Xenova Group plc
+44 (0)1753 706600
David A. Oxlade, Chief Executive Officer
Daniel Abrams, Finance Director
Veronica Cefis Sellar, Head of Corporate Communications

UK - Financial Dynamics
+44 (0)20 7831 3113
David Yates
Ben Atwell

US - Trout Group/BMC Communications
+1 212 477 9007
Media: Brad Miles
Investors: Lee Stern