August 17 2009
BTG Collaborator Onyx Gains Approval to Progress Oncology Compound into Clinical Development

London, UK, 17 August 2009

BTG plc (LSE: BGC), the specialty pharmaceuticals company, today announces that Onyx Pharmaceuticals, Inc. (Nasdaq: ONXX) has received authorisation for a Clinical Trial Application from the UK's Medicines and Healthcare products Regulatory Agency to initiate a Phase I clinical study of ONX 0801 (formerly BGC 945), triggering a $7m milestone payment from Onyx to BTG.　

ONX 0801 is a novel compound that inhibits thymidylate synthase (TS), an enzyme involved in cell growth and division. Unlike traditional TS inhibitors, it enters tumour cells primarily via the alpha-folate receptor, which is over-expressed in certain tumour types but has a restricted expression profile in normal tissues. This may lead to sparing of healthy cells and potentially fewer side effects and lower toxicity during treatment.

Louise Makin, BTG's chief executive officer, commented: "This is an important milestone in the development of ONX 0801, which may provide significant benefits in the treatment of a range of cancer types. We look forward to continued progress by Onyx."

BTG granted worldwide rights to Onyx to develop and commercialise BGC 945 in November 2008, in return for an upfront payment of $13m, potential development and commercial milestones totalling $307m and a royalty on product sales. Prior to licensing Onyx, BTG had progressed BGC 945 into late-stage preclinical development in collaboration with The Institute of Cancer Research, where the compound was discovered.

For further information contact:

BTG
Andy Burrows, Director of Investor Relations
Tel: +44 (0)20 7575 1741
Mobile: +44 (0)7990 530605

Rolf Soderstrom, Chief Financial Officer
+44 (0)20 7575 0000

Financial Dynamics
Ben Atwell
+44 (0)20 7831 3113