GLAXOSMITHKLINE AND ANACOR PHARMACEUTICALS FORM ALLIANCE TO DEVELOP SYSTEMIC ANTIVIRALS AND ANTIBIOTICS BASED ON BORON CHEMISTRY

- Innovative approach to developing anti-infective medicines provides hope for combating problems of resistance -

Palo Alto, Calif., and London, UK - October 8, 2007 - Anacor Pharmaceuticals and GlaxoSmithKline today announced that they have entered into a worldwide strategic alliance for the discovery, development and commercialization of novel medicines for viral and bacterial diseases. The collaboration provides GlaxoSmithKline access to Anacor's proprietary boron-based chemistry for use against selected targets.

GlaxoSmithKline will participate in the alliance through its Infectious Diseases Centre of Excellence for Drug Discovery (ID CEDD). Under the terms of the agreement, Anacor will grant GlaxoSmithKline options to select product candidates developed under the collaboration that are directed to up to four discovery targets and with the potential for at least eight product options. Anacor will primarily be responsible for the discovery and development of boron-containing small molecule drug candidates through clinical proof of concept, at which point GlaxoSmithKline will have an exclusive option to license each compound for further development and commercialization on a worldwide basis. Anacor will have the right to further develop and commercialize compounds for which GlaxoSmithKline does not exercise its option. Anacor will receive a $12 million upfront payment and a $10 million equity financing commitment from GlaxoSmithKline. Contingent on achieving certain milestones, Anacor is eligible to receive discovery, development, regulatory and commercial milestones ranging up to $252 million and $331 million for each product candidate. If GlaxoSmithKline exercises its option at the proof of concept stage, Anacor will receive tiered double digit royalties, which are dependent on sales achieved.

Boron has been a relatively underutilized element in pharmaceutical products, in part due to a lack of naturally occurring boron-containing molecules to guide rational drug design. As a consequence of boron's unique properties, boron containing molecules may access different chemical space than traditional anti-infectives, providing opportunities for structural and biological novelty. Anacor's proprietary technological advances in the synthesis of boron-based compounds coupled with its rational drug design expertise, has enabled the company to rapidly create diverse families of boron-based compounds.

"We are pleased that GlaxoSmithKline, an industry leader in the development and commercialization of anti-infective d rugs has acknowledged the potential of our boron-based chemistry for systemic applications," said David Perry, President and Chief Executive Officer. "This agreement with GlaxoSmithKline is consistent with our strategy to maximize the value of our technology platform by forming early collaborations for systemic applications of our boron technology, while developing topical products on our own to a more advanced stage."

"GlaxoSmithKline recently created a single Centre of Excellence for Drug Discovery dedicated to Infectious Diseases," said Zhi Hong, Senior Vice President and Head of GlaxoSmithKline's ID CEDD. "We recognize the issues created by resistance to available medicines and are determined to take advantage of novel approaches that offer new prospects for treatments across a range of infectious diseases. Anacor's boron-based chemistry has shown promise in inhibiting targets that are difficult to address with traditional carbon-based molecules and we look forward to further exploring its potential to provide new antiviral and antibiotic options."

About Anacor Pharmaceuticals
Anacor is a biopharmaceutical company developing novel small molecule therapeutics derived from its boron chemistry platform. Anacor has focused initially on developing topical applications of its compounds to treat fungal, bacterial and inflammatory diseases. Anacor's most advanced product candidate is AN2690, a novel topical antifungal in development for the treatment of toenail onychomycosis, which is a fungal infection of the nail and nail bed. Anacor entered into a worldwide license, development and commercialization agreement for AN2690 with Schering-Plough for all indications including the treatment of onychomycosis. In addition, Anacor has a portfolio of other topical product candidates in development for the treatment of psoriasis, gingivitis, acne, vaginal candidiasis and tinea pedis.

About GlaxoSmithKline
GlaxoSmithKline, one of the world's leading research-based pharmaceutical and healthcare companies, is committed to improving the quality of human life by enabling people to do more, feel better and live longer. For information about GlaxoSmithKline visit the company website at www.GSK.com.

About The ID CEDD
The ID CEDD is a global research unit within GlaxoSmithKline Drug Discovery dedicated to discovering therapies for infectious diseases. It is designed to integrate and better coordinate the progression of infectious diseases medicines from therapeutic hypothesis to clinical proof of concept. While drawing from the broader resources of GlaxoSmithKline's R&D organization, the ID CEDD bridges the conventional gap between discovery and development, brings scientists and physicians together in an environment and size of small biotechnology companies. It focuses on building an innovative pipeline through both internal efforts and external alliances with other companies and research institutions. Its Centre of Excellence for External Drug Discovery (ID CEEDD) will focus on 'virtualising' a portion of the infectious diseases pipeline by forming multiple risk-sharing/reward-sharing alliances.

GSK cautionary statement regarding forward-looking statements
Under the safe harbour provisions of the U.S. Private Securities Litigation Reform Act of 1995, the company cautions investors that any forward-looking statements or projections made by the company, including those made in this Announcement, are subject to risks and uncertainties that may cause actual results to differ materially from those projected. Factors that may affect the Group's operations are described under 'Risk Factors' in the 'Business Review' in the company's Annual Report on Form 20-F for 2006.

Anacor Forward-Looking Statements
This press release contains forward-looking statements, including statements regarding the expected closing of the collaboration agreement, GlaxoSmithKline's financing commitment to Anacor, the discovery, development and commercialization of novel medicines pursuant to the collaboration, future payments of milestone and royalty amounts to Anacor and the potential of Anacor's boron-based chemistry to inhibit targets that are difficult to address with traditional carbon-based molecules or have developed resistance to currently available treatments. These statements relate to future events and involve known and unknown risks, uncertainties and other factors that could cause actual levels of activity, performance or achievement to differ materially from those expressed or implied by these forward-looking statements. Some factors that may affect these forward-looking statements include, but are not limited to, the ability of the parties to collaborate successfully to develop drug candidates, the results of future drug discovery, development and commercialization efforts, including proof of safety and efficacy in clinical trials, the ability to obtain regulatory approvals for drug candidates identified through the collaboration, and the introduction of competing therapies by other companies. These statements reflect the views of Anacor as of the date of this press release with respect to future events and, except as required by law, it undertakes no obligation to update or revise publicly any forward-looking statements, whether as a result of new information, future events or otherwise after the date of this press release.