Patent Grant

Allergy Therapeutics PLC
03 December 2004



                          Allergy Therapeutics plc

         Allergy Therapeutics granted UK patent for sublingual vaccine

Allergy Therapeutics (LSE: AGY), the specialty pharmaceuticals company focused
on allergy vaccines, announced today it has been granted the first patent for
its family of MPL(R)-based sublingual vaccines, by the UK patent office.

Allergy Therapeutics believes a sublingual allergy vaccine has significant
potential to capture market share from symptomatic treatments, such as
antihistamines, as it could be self-administered at home and prescribed by
general practitioners. Allergy Therapeutics is developing a sublingual vaccine
incorporating MPL(R), which is at the proof of concept stage, the outcome of
which is expected in the first half of 2005.

The patent is very broad, covering all antigens, and therefore could cover
vaccines for any mucosally-transmitted disease as well as allergy. It has been
granted jointly to Allergy Therapeutics and Corixa, from which Allergy
Therapeutics originally licenced MPL(R) for use in allergy vaccines.

Commenting on the granting of the patent, Keith Carter, Chief Executive of
Allergy Therapeutics, said:

"The granting of this patent marks a milestone for the company as it is the
first we have received for a sublingual product in any jurisdiction. Current
sublingual allergy vaccines such as our own Oralvac(R) are efficacious but less
so than injected vaccines and only after daily dosing lasting one or more years.
It is our hope that the incorporation of our patented adjuvant MPL(R) will
result in a more efficacious sublingual vaccine with a short dosing schedule.
The sublingual development pipeline is at an early stage but we believe it has
the potential to mount a real challenge to the dominance of antihistamines in
the treatment of allergies."

                                                                 3 December 2004

For further information:

Allergy Therapeutics                       01903 844720
Keith Carter, Chief Executive

KBC Peel Hunt Ltd                          020 7418 8900
Capel Irwin

Grandfield                                 020 7417 4181
Samantha Robbins


NOTES TO EDITORS

Allergy market

Current allergy treatment is almost exclusively concerned with the management of
allergic symptoms using drugs such as anti-histamines and steroids supplemented
with, in the case of allergic asthma, drugs to improve breathing such as
B-agonists. These medicines are available, as oral or inhaled formulations, by
prescription and over-the-counter ("OTC"). Although these palliative drugs
provide temporary symptomatic relief, they can be inconvenient to use and can
cause unwanted side effects. Most importantly, they need to be administered
chronically and do not modify the underlying disease state, nor do they prevent
the so-called Allergic March from seasonal/perennial rhino-conjunctivitis to
allergic asthma. Sales of these palliative symptomatic anti-allergy drugs exceed
US$12 billion.

An alternative to this palliative treatment is allergy vaccination (also
referred to as specific immunotherapy or de-sensitisation). Allergy vaccination
(both injectable and sublingual) is currently the only treatment for Type 1
Allergy hypersensitivity that can alter or cure the underlying disease process.

Allergy vaccine market

Conventional immunotherapy is a gradual immunisation process in which increasing
individualised concentrations of pollen extracts are administered to induce
increased tolerance to natural allergen exposure. Practice varies, but typically
the procedure involves weekly or monthly doses of the offending allergens which,
over time, induce immunological tolerance. Three years or more of allergy
vaccination is required for long term effect of the treatment. Because of the
number of injections (as many as 180), length of treatment and potential risk of
serious side effects, a significant portion of patients do not complete the
therapy course. As a result, allergy vaccination has less than a 5 per cent.
market share in most markets.

It is unsurprising that conventional immunotherapy has not captured a
significant portion of the growing market for the treatment and prevention of
allergies because its complexity and risk limits its use to qualified allergists
and limits its attractiveness to patients. Hence Allergy Therapeutics believes
that capturing maximum market share with allergy vaccines will come by improving
the characteristics of the products. Allergy Therapeutics' short term,
well-tolerated, safe and effective MPL(R)-based vaccines are designed, once
registered, to achieve this market expansion.

While sublingual vaccines have the advantage of not requiring injections, they
currently have the disadvantage of requiring daily administration under the
tongue and efficacy (relief from allergic symptoms), usually takes more than one
year of vaccine administration before reaching significant levels. The
pre-clinical work upon which the newly granted patent is based suggests that a
mucosally-delivered MPL(R)-containing vaccine may be effective more rapidly and
with fewer doses required.

About MPL(R)

MPL(R) monophosphoryl lipid A. is a Lipopolysaccharide ("LPS") derived from the
cell walls of salmonella minnesota that has been purified and detoxified. The
non-specific human immune response system recognises LPS as being derived from
bacterial sources and reacts to LPS as though it was a bacterial infection. As a
result, the immune system mounts a cell-mediated immune response (TH1) and
synthesises IgG specific to the challenging material, which in combination with
the allergoid creates a rapidly efficacious product. The clinical experience
with MPL(R) is extensive, demonstrating the adjuvant to be safe, well-tolerated
and effective for human use.



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