Idenix Pharmaceuticals Announces $20 Million Milestone Payment From ViiV Healthcare for Initiation of Phase IIb Trial of '761

CAMBRIDGE, Mass., Nov. 23, 2010 /PRNewswire-FirstCall/ -- Idenix Pharmaceuticals, Inc. (Nasdaq: IDIX), a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral diseases, today announced that the Company will receive a payment of $20 million from the ViiV Healthcare Company for the achievement of a clinical milestone relating to GSK2248761 (known as '761).  ViiV Healthcare is developing '761, a drug candidate for the treatment of HIV/AIDS.

"We are pleased with the continued progress of '761 and the initiation of a Phase IIb clinical trial in HIV-infected patients," said Ronald Renaud, president and chief executive officer of Idenix. "We look forward to the continued progress of this program."

Relationship with ViiV Healthcare

In February 2009, Idenix licensed to GlaxoSmithKline (GSK) on a worldwide basis a non-nucleoside reverse transcriptase inhibitor (NNRTI) drug candidate, '761, for the treatment of HIV/AIDS. The Company has received approximately $60 million in total collaboration-related payments as of November 2010. Under this agreement, Idenix could also potentially receive up to $390 million in additional milestone payments as well as double-digit tiered royalties on worldwide product sales. In November 2009, GSK and Pfizer created ViiV Healthcare, an independent company focused solely on research, development and commercialization of HIV medicines, and '761 became part of the ViiV Healthcare pipeline.

About Idenix

Idenix Pharmaceuticals, Inc., headquartered in Cambridge, Massachusetts, is a biopharmaceutical company engaged in the discovery and development of drugs for the treatment of human viral diseases. Idenix's current focus is on the treatment of patients with chronic hepatitis C infection. For further information about Idenix, please refer to www.idenix.com.