Research Programme Update

Sareum Holdings PLC
06 February 2007


For immediate release                                          6 February 2007



   SAREUM HOLDINGS PLC, THE INSTITUTE OF CANCER RESEARCH AND CANCER RESEARCH
                                 TECHNOLOGY LTD





          Progression of Checkpoint Kinase 1 Drug Discovery Programme



Sareum Holdings plc (Sareum) (AIM: SAR), the specialist structure-based drug
discovery business, The Institute of Cancer Research (The Institute), Europe's 
leading cancer research centre, and Cancer Research Technology Limited (CRT), 
the oncology focused development and commercialisation company, are pleased 
to announce that novel small molecule compounds, the subject of a series of 
patent filings, show activity in targeting Checkpoint Kinase 1 (CHK1).

CHK1 is a key component of a biochemical pathway responsible for preventing the
effectiveness of traditional cancer therapeutics such as chemotherapy and is the
primary target of the joint collaboration. The aim of the programme, first
announced in July 2005, is to develop potential cancer treatments with valuable
benefits for cancer patients including lower doses of existing therapies, fewer
adverse side-effects and efficacy where tumours currently do not respond to
chemotherapy.  In August 2006 Sareum announced that the collaboration had
discovered a novel compound series which showed activity in cancer cell models.

The patent filings are part of an ongoing strategy to secure the intellectual
property rights relating to the novel compound series developed from this
collaboration, their effectiveness in inhibiting CHK1 function and their use in
the treatment of cancer.

Sareum has used its expertise in fragment and structure-based drug discovery to
identify novel chemical compounds effective against CHK1.  These compound series
have been rapidly progressed towards drug candidates utilising Sareum[?c=8217]s
high throughput medicinal chemistry and structure determination platforms
combined with the drug screening, specialist cancer biology and medicinal
chemistry expertise at The Cancer Research UK Centre for Cancer Therapeutics at
The Institute.

Under the terms of the collaboration agreement, CRT will commercialise the drug
candidates developed by the collaboration to secure future clinical development.
Payments, milestones and royalties received by CRT will be shared with Sareum
and The Institute.

Commenting on the announcement, Sareum[?c=8217]s Chief Executive Officer, Dr Tim
Mitchell, said: [?c=8220]The progress of these compounds represents an important
milestone in Sareum[?c=8217]s strategy to generate value through our in-house
drug discovery. We are now looking forward to advancing our novel chemical
series through to clinical candidate nomination.[?c=8221]

Professor Paul Workman, Director of The Cancer Research UK Centre for Cancer
Therapeutics at The Institute of Cancer Research, said: "We are very pleased 
with the progress that has been made so far with this project. By utilising 
the complementary expertise of each organisation we can speed up the drug 
development process and bring new treatments to patients as soon as possible."


Sareum Holdings plc                                            01223 497700

Tim Mitchell, Chief Executive Officer


Buchanan Communications                                        020 7466 5000

Tim Anderson, Mary-Jane Johnson


The Institute of Cancer Research                               020 7153 5359
Nadia Ramsey, Press Officer


Cancer Research Technology Limited                             0207 269 3640
Nick Wells, Head of Marketing



Notes for editors:


About Checkpoint Kinase 1

Many known cancer treatments cause DNA damage by either physically modifying the
cell[?c=8217]s DNA or disrupting vital cellular processes that can affect the
fidelity of DNA replication and cell division, such as DNA metabolism, DNA
synthesis, DNA transcription and microtubule spindle formation.  Such treatments
include for example, radiotherapy, which causes DNA strand breaks, and a variety
of chemotherapeutic agents including topoisomerase inhibitors, antimetabolites,
DNA-alkylating agents, and platinum-containing cytotoxic drugs.  A significant
limitation to these genotoxic treatments is drug resistance.  One of the most
important mechanisms leading to this resistance is attributed to activation of
cell cycle checkpoints, giving the tumour cell time to repair damaged DNA.  By
abrogating a particular cell cycle checkpoint, or inhibiting a particular form
of DNA repair, it may therefore be possible to circumvent tumour cell resistance
to the genotoxic agents and augment tumour cell death induced by DNA damage,
thus increasing the therapeutic index of these cancer treatments.

Checkpoint Kinase 1 (CHK1) is a serine/threonine kinase involved in regulating
cell cycle checkpoint signals that are activated in response to DNA damage and
errors in DNA caused by defective replication (see, e.g., Bartek and Lukas,
2003).  CHK1 transduces these signals through phosphorylation of substrates
involved in a number of cellular activities including cell cycle arrest and DNA
repair.  Two key substrates of CHK1 are the Cdc25A and Cdc25C phosphatases that
dephosphorylate CDK1 leading to its activation, which is a requirement for exit
from G2 into mitosis (M phase)..  Phosphorylation of Cdc25C and the related
Cdc25A by CHK1 blocks their ability to activate CDK1, thus preventing the cell
from exiting G2 into M phase.  The role of CHK1 in the DNA damage-induced G2
cell cycle checkpoint has been demonstrated in a number of studies where CHK1
function has been knocked out.

The reliance of the DNA damage-induced G2 checkpoint upon CHK1 provides one
example of a therapeutic strategy for cancer treatment, involving targeted
inhibition of CHK1.  Upon DNA damage, the p53 tumour suppressor protein is
stabilised and activated to give a p53-dependent G1 arrest, leading to apoptosis
or DNA repair.  Over half of all cancers are functionally defective for p53,
which can make them resistant to genotoxic cancer treatments such as ionising
radiation (IR) and certain forms of chemotherapy.  These p53 deficient cells
fail to arrest at the G1 checkpoint or undergo apoptosis or DNA repair, and
consequently may be more reliant on the G2 checkpoint for viability and
replication fidelity.  Abrogation of the G2 checkpoint through inhibition of the
CHK1 kinase function has been demonstrated to selectively sensitise p53
deficient cancer cells to genotoxic cancer therapies.



About Sareum Holdings plc

Sareum Holdings plc is a structure-based drug discovery business headquartered
in Cambridge, UK. The Company was formed in August 2003 to discover new drugs
for the treatment of cancer.  Sareum[?c=8217]s unique approach aims to halve the
time it takes to discover new drug candidates.

A structure-based approach to drug discovery relies on knowledge of the
three-dimensional structure of the proteins that cause disease.  Once the
structure is known, potential drugs are designed to [?c=8216]lock-in[?c=8217] to
the protein with the aim of reversing or arresting a disease[?c=8217]s
progression.  Knowledge of the structure of the potential drugs and how they
[?c=8216]lock-in[?c=8217] to their target protein assists greatly in the
development of high-quality drug candidates.  Determining structure is a complex
task and requires leading-edge equipment and experienced staff.  Sareum[?c=8217]
s approach to structure determination utilises its proprietary protein
expression platform in order to produce multiple recombinant proteins that
accelerate structure determination using x-ray crystallography.

Once the structure is determined, the Company[?c=8217]s innovative fragment
screening platform is used to identify novel chemical templates designed to
interact with the target protein.  Sareum then uses its high-throughput
medicinal chemistry platform to rapidly optimise these molecules and develop the
most promising into potential drug candidates.

Sareum aims to successfully deliver drug candidates for licensing to larger
pharmaceutical companies at the pre-clinical or early clinical trials stage.
This is funded by provision of its specialist drug discovery capabilities to
partners in the pharmaceutical and biotechnology industries.

Sareum joined the AIM market of the London Stock Exchange in October 2004 and
trades under the symbol SAR.  For further information, please visit
www.sareum.co.uk

About The Institute of Cancer Research

The Institute of Cancer Research is Europe's leading cancer research centre with
expert scientists working on cutting edge research. It was founded in 1909 to
carry out research into the causes of cancer and to develop new strategies for
its prevention, diagnosis, treatment and care. For more information please visit
www.icr.ac.uk

The Institute works in a unique partnership with the Royal Marsden NHS
Foundation Trust, forming the largest comprehensive cancer centre in Europe. The
Institute is unrivalled in its record in cancer drug discovery and development.

The Institute is a charity that relies on voluntary income. The Institute is a
highly cost-effective major cancer research organisation with over 90p in every
£ directly supporting research.



About Cancer Research Technology Limited

Cancer Research Technology Limited (CRT) is an oncology-focused development and
commercialisation company that realises cancer patient benefit from publicly-
funded research worldwide. CRT works closely with leading international cancer
scientists, their institutes and funding bodies to protect, develop and
commercialise oncology-related discoveries. CRT is wholly owned by Cancer
Research UK, the largest independent funder of cancer research in the world.
Further information about CRT can be found at www.cancertechnology.com.






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