Cyclacel Announces Publication of Penetratin® Drug Conjugate Patent Application

DUNDEE - 24 February 2000 - Cyclacel Limited, the UK-based cancer therapeutics company, today announced the publication of a patent application relating to its Penetratin®-Drug Conjugation technology. This technology is the basis of Cyclacel's CYC300 drug programme of novel cancer therapeutics, combining Penetratin with existing cytotoxic drugs.

PCT (Patent Cooperation Treaty) application number WO 00/01417 claims the use of Penetratin, a patented endonuclear drug delivery peptide, linked to small molecule drugs. The linked combination or conjugate can alter the physical, chemical and delivery properties of such drugs. CYC300 conjugates have the potential of increasing the therapeutic index of existing drugs by altering both their efficacy and toleration. The patent application also claims improvements in linker technology and peptide stability and a shortened version of the Penetratin peptide.

Cyclacel scientists developed a proprietary, shortened version of the peptide the length of which is less than half that of the original. The shortened peptide was developed by exploiting the understanding of the structure-activity relationship (SAR) between the peptides and the cells they enter into, as recently reported in the Journal of Peptide Research (2000:55:163). The shortened version could enhance the commercial potential of the Penetratin technology as it could make resulting drug conjugates easier and less costly to manufacture.

Professor Sir David Lane, Cyclacel's Chief Scientific Officer said: "Cyclacel's achievement of stable versions of Penetratin-drug conjugates and our control of linker technology make this system a valuable part of our cancer therapeutics pipeline, which also includes other mechanism-based approaches such as small molecule inhibitors of the cell cycle. The shortened form of Penetratin is an important technical advance by Cyclacel scientists and adds increased versatility to a promising technology. In addition to cancer, this technology may have applications in many other therapeutics areas."