PVG.L Regulatory News (PVG)

31 May 2007 07:02

Ark Therapeutics Group PLC31 May 2007 New study shows Scavidin(R) is effective in slowing tumour development and improving survival time Demonstrates potential of Ark's unique DNA-based targeting technology to reduce side effects and increase efficacy of chemotherapy and other pharmaceuticals London, UK, 31 May 2007: Ark Therapeutics Group plc announces today that itsnovel gene-based drug targeting platform technology, Scavidin(R), has shownfurther pre-clinical evidence of being highly effective in slowing tumourdevelopment and significantly improving survival time using a low dose of theradiotherapy Yttrium90 which would be sub-therapeutic if administeredconventionally. Scavidin(R) was used to target and concentrate intravenous doses ofapproximately one-fifth the conventional levels of the radioisotope Yttrium90 ina model of malignant glioma, a particularly aggressive and fatal form of braintumour. In the model, the treatment group survived 32% longer on average (p<0.0001) than those given Yttrium90 without Scavidin(R) or untreated controls.Scavidin(R) DNA was transfected into the brain tumours using a viral vector.Biotin-tagged Yttrium90 was given intravenously at a sub-therapeutic dose.Yttrium90without Scavidin(R) was used as the treatment control. Only whereScavidin(R) had been transfected was an improvement in survival observed. Nomajor side-effects were observed. In February 2006 Ark announced its initial evidence of effective tumour controlwith between a fifth and a tenth of the conventional doses of Yttrium90 andpaclitaxel in cancer models of tumour growing under the skin. The results todayprovide further evidence of the potential wide utility for this leading edgetechnology in very large markets. Ark will now continue to optimise the vector and dosing regimes and explore thefull concentration gradient capabilities of Scavidin(R). It will also continuepre-clinical toxicity work prior to commencing clinical studies after consultingwith the regulators. Nigel Parker, CEO of Ark, commented: "Our previous model results had shown effective tumour control and now thisthird model has shown this translates into improved survival time at anYttrium90 dose which, if used conventionally, would have no effect. Scavidin(R)has the potential to improve the therapeutic effect and reduce the unpleasantside-effects of a wide variety of drugs, most obviously chemotherapy and otherpotent anti-cancer agents, but also in many other therapies where theside-effects are high and thus dose-limiting." Dr David Eckland, Ark's Research and Development Director,,added: "Scavidin(R) targeting technology offers the possibility of cancer patientsbeing given up to a 10 times lower dose of an anti-cancer drug than inconventional treatment approaches. This could markedly reduce side-effects suchas hair loss and vomiting and enable the treatment to be repeated more easily.It also allows the anti-cancer drug to be concentrated into the tumour at higherlevels and thus its biological 'cancer cell killing' efficacy can be verysubstantially increased." For further information please contact: Ark Therapeutics +44 (0)20 7388 7722Dr Nigel Parker, Chief ExecutiveMartyn Williams, CFO Financial Dynamics +44 (0)20 7831 3113David Yates/Anna Keeble Scientific Notes Scavidin(R) is a novel two-part drug targeting technology originating from theDNA which expresses a specific LDL receptor on white blood cells. This naturalreceptor usually collects undesired fats and damaged cells and membranes fromthe blood, taking them into the white blood cells and releasing them fordestruction as part of the body's natural 'clean up' system. By modifying theDNA sequence for such receptor types, Ark has developed a new family ofreceptors which specifically bind only to the protein biotin, a naturallyoccurring substance which can easily be attached to therapeutic agents. The Scavidin(R) DNA is put into the tumour where it expresses the new drugtargeting receptor. The therapeutic agent, pre-tagged with biotin, is thengiven intravenously at low doses. As the therapeutic agent circulates roundthe body, Scavidin(R) extracts it from the blood by binding to the biotin tag,taking it into the cell and releasing it. The receptor then goes back andcollects more. This revolutionary 'molecular shuttle' system concentrates thetherapeutic agent from a low and ineffective dose in the blood to a hightherapeutic dose specifically in the target tissue. In this way an importantand highly effective therapeutic, which could have a poor safety profile (suchas chemotherapy with high unwanted side-effects) at a traditional dose, may begiven in a low and safe dose systemically, with Scavidin(R) concentrating itspecifically at the disease site where its treatment effect is needed. As such,it has enormous potential across many disease areas. Scavidin(R) was discovered by Ark scientists in Kuopio, Finland. Basedprincipally on the scavenger and low density lipoprotein receptors, the Scavidin(R) DNA contains a sequence causing the receptor (technically a fusion protein)to be expressed with the protein avidin as the 'collecting head'. Avidin bindsonly to biotin with a bond strength (10-14) almost twice that of anantibody-antigen bond and, as such, is a highly specific and powerful targetingconstruct. In vitro and in vivo mechanistic proof of priniciple of Scavidin(R)'sability to concentrate molecules from the blood into a target tissue in modelshas demonstrated that Scavidin(R) is able to concentrate a range of differentbiotinylated agents from small radioisotopes like Technetium99m and Yttrium90,through larger molecules like ferritin complexes and horseradish peroxidasestain and paclitaxel to large organic molecules like immunoglobulin. Evidence ofScavidin(R)'s binding strength has been confirmed using atomic force microscopy. By switching between tetra avidin and mono avidin constructs, Scavidin(R)'sbinding abilities can be varied between 10-14 and 10-7 allowing wide drugretention variation and by modifying other DNA regions, Scavidin(R) can bemodified to hold a therapeutic agent on the cell surface or slowly or rapidlyinternalise it. Scavidin(R) has been administered successfully with standardgene medicine vectors, such as adenovirus, retrovirus and semliki forest virus,and the Company currently favours lentivirus as the integrational vector.Scavidin(R) intellectual property is owned exclusively by Ark Therapeutics andis covered by granted patents or applications undergoing prosecution until 2019. Ark Therapeutics Group plc Ark Therapeutics Group plc is a specialist healthcare group (the "Group"),addressing high value areas of unmet medical need within vascular disease, woundcare and cancer. These are large and growing markets, where opportunities existfor effective new products to generate significant revenues. With two marketeddevices, Kerraboot(R), and Flaminal(R), and three further lead pharmaceuticalproducts in late stage clinical development: CereproTM, VitorTM, and Trinam(R),the Group is transitioning from an R&D company to a commercial, revenuegenerating business. Ark's existing products are sourced from related but largely non-dependenttechnologies within the Group and have been selected to enable them to be takenthrough development within the Group's own means and to benefit from Orphan DrugStatus and/or Fast Track Designation, as appropriate. This strategy has allowedthe Group to retain greater value and greater control of clinical developmenttimelines, and to mitigate the risks of dependency on any one particularprogramme or development partner. Ark has secured patents or has patentapplications pending for all its lead products in principal pharmaceuticalmarkets. Ark has its origins in businesses established in the mid-1990s by Professor JohnMartin and Mr Stephen Barker of University College London and Professor SeppoYla-Herttuala of the AI Virtanen Institute at the University of Kuopio,Finland, all of whom play leading roles in the Company's research anddevelopment programmes. Ark's shares were first listed on the London Stock Exchange in March 2004(AKT.L). This announcement includes "forward-looking statements" which include allstatements other than statements of historical facts, including, withoutlimitation, those regarding the Group's financial position, business strategy,plans and objectives of management for future operations (including developmentplans and objectives relating to the Group's products and services), and anystatements preceded by, followed by or that include forward-looking terminologysuch as the words "targets", "believes", "estimates", "expects", "aims","intends", "will", "can", "may", "anticipates", "would", "should", "could" orsimilar expressions or the negative thereof. Such forward-looking statementsinvolve known and unknown risks, uncertainties and other important factorsbeyond the Group's control that could cause the actual results, performance orachievements of the Group to be materially different from future results,performance or achievements expressed or implied by such forward-lookingstatements. Such forward-looking statements are based on numerous assumptionsregarding the Group's present and future business strategies and the environmentin which the Group will operate in the future. Among the important factors thatcould cause the Group's actual results, performance or achievements to differmaterially from those in forward-looking statements include those relating toArk's funding requirements, regulatory approvals, clinical trials, reliance onthird parties, intellectual property, key personnel and other factors. Theseforward-looking statements speak only as at the date of this announcement. TheGroup expressly disclaims any obligation or undertaking to disseminate anyupdates or revisions to any forward-looking statements contained in thisannouncement to reflect any change in the Group's expectations with regardthereto or any change in events, conditions or circumstances on which any suchstatements are based. As a result of these factors, readers are cautioned not torely on any forward-looking statement. This information is provided by RNS The company news service from the London Stock Exchange