Initiation triggers USD 25 million milestone payment from Novartis

London, UK, and Princeton, NJ, 11 April 2008 - Cancer drug developerAntisoma plc (LSE: ASM; US OTC: ATSMY) announces that its partnerNovartis has started the pivotal phase III trial of ASA404 combinedwith first-line chemotherapy in non-small cell lung cancer (NSCLC).The study, called ATTRACT-1, is designed to support applications formarketing authorisations in the US, Europe and other territories. Itsinitiation triggers a USD 25 million milestone payment to Antisoma.

Glyn Edwards, Antisoma's CEO, said: "We're delighted that the phaseIII trial in lung cancer is underway, putting ASA404 on a clear pathtowards potential marketing applications. Lung cancer is anindication with substantial unmet clinical need and blockbuster salespotential, and Novartis' trial is optimally designed to seekconfirmation of the positive results seen in our two phase II lungcancer studies."

Two webcasts/conference calls will be held today at 9:30am BST /4:30am EST and at 2pm BST / 9am EST. The webcasts can be accessed viaAntisoma's website at http://www.antisoma.com/ and the calls bydialling +44 (0)20 8609 1435 (UK toll-free 0808 109 1498; UStoll-free 1866 793 4279) and using the participant PIN code 816385#.Recordings will also be available afterwards on the Antisoma website.

About the phase III trial

The ATTRACT-1 trial is a randomised, double-blind,placebo-controlled, multicentre phase III trial being conductedacross the US, EU and other territories. With 1200 patients, it willbe amongst the largest trials conducted in NSCLC. ATTRACT-1 is opento patients with all histologies, or types, of NSCLC, includingsquamous and non-squamous cancers. Patients are being randomised 1:1to receive either ASA404 1800 mg/m2 plus chemotherapy(carboplatin/paclitaxel) or a placebo plus chemotherapy(carboplatin/paclitaxel) as a control. The primary endpoint of theATTRACT-1 trial is overall survival. Key secondary endpoints aresurvival in the squamous and non-squamous patient subgroups.

If the trial results are positive, applications for marketingauthorisations are anticipated in 2011. There will be a singlescheduled interim look during the trial, expected in mid-late 2009.

About NSCLC

Lung cancer is the number one cause of cancer death for both men andwomen worldwide, with 1.2 million new cases per year and 921,000deaths. Around 85-90% of all lung cancer cases are NSCLC.

About ASA404

ASA404 (DMXAA) is a small-molecule tumour vascular disrupting agent(tumour VDA) which targets the blood vessels that nourish tumours.The drug was discovered by Professors Bruce Baguley and William Dennyand their teams at the Auckland Cancer Society Research Centre,University of Auckland, New Zealand. It was in-licensed by Antisomafrom Cancer Research Ventures Limited (now Cancer ResearchTechnology), the development and commercialisation company of theCancer Research Campaign (now Cancer Research UK), in August 2001.Worldwide rights to the drug were licensed to Novartis AG in April2007.

About ASA404 in NSCLC

ASA404 has shown a substantial survival benefit in patients withnon-small cell lung cancer when added to paclitaxel-basedchemotherapy in a randomised phase II study. A second, single-arm,phase II study of ASA404 in non-small cell lung cancer has alsoreported positive results.

About Antisoma

Headquartered in London, UK, Antisoma is a biopharmaceutical companythat develops novel products for the treatment of cancer. Antisomafills its development pipeline by acquiring promising new productcandidates from internationally recognised academic or cancerresearch institutions. Its core activity is the preclinical andclinical development of these drug candidates. Please visitwww.antisoma.com for further information about Antisoma.

Enquiries:Glyn Edwards, CEODaniel Elger, Director of Communications          +44 (0)7909 915 068Antisoma plcMark Court/Lisa Baderoon/Rebecca Skye             +44 (0)20 7466 5000DietrichBuchanan CommunicationsBrian Korb                                        +1 646 378 2923The Trout Group

Except for the historical information presented, certain mattersdiscussed in this statement are forward looking statements that aresubject to a number of risks and uncertainties that could causeactual results to differ materially from results, performance orachievements expressed or implied by such statements. These risks anduncertainties may be associated with product discovery anddevelopment, including statements regarding the company's clinicaldevelopment programmes, the expected timing of clinical trials andregulatory filings. Such statements are based on management's currentexpectations, but actual results may differ materially.

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