Metabasis Therapeutics Announces Positive Results in the Phase 2a Clinical Trial for MB07803, Its Product Candidate for the Treatment of Type 2 Diabetes

SAN DIEGO -- April 28, 2008--Metabasis Therapeutics announced today that MB07803 met its primary efficacy endpoint with results demonstrating a statistically and clinically significant reduction in fasting plasma glucose (FPG) at day 28 in its Phase 2a clinical trial. The study also showed that MB07803 was safe and well tolerated. MB07803 is Metabasis' product candidate for the treatment of type 2 diabetes that acts by inhibiting fructose-1,6-bisphosphatase (FBPase).

This 28-day proof-of-concept clinical trial was a randomized, double-blind, placebo-controlled trial involving 105 patients with type 2 diabetes with a mean baseline fasting plasma glucose of 187 mg/dL and mean baseline HbA1c of 8.2%. Patients received either placebo or MB07803 at an oral dose of 10, 50, 100 or 200 mg once daily. The primary efficacy endpoint of the study was change in FPG at day 28 from baseline.

The primary efficacy endpoint of the trial was achieved with MB07803 administered at 200 mg once a day resulting in a statistically and clinically significant reduction in FPG at day 28 versus placebo (p=0.0177). This clinical trial showed that MB07803 was safe and well tolerated with 94% of the patients completing the study and no patients withdrawing due to drug-related adverse events. The overall adverse event profile was similar to that of the placebo. Fasting lactate levels were within the normal range and no patients experienced hyperlacticemia (a sustained lactate elevation above 4.5 mM). The Company plans to present full clinical trial results at a major international scientific conference later this year.

MB07803 is Metabasis' second-generation product candidate for the treatment of type 2 diabetes and part of a new class of drugs that the Company discovered internally using its NuMimetic(TM) technology. MB07803 regulates excess glucose production in the liver by inhibiting the enzyme, FBPase, a key component in the gluconeogenesis pathway. Excess hepatic glucose production is believed to be a major contributing factor to the elevated glucose levels associated with increased morbidity and mortality in patients with type 2 diabetes.

"The results of this study provide, for the first time, evidence that MB07803 lowers fasting plasma glucose levels in patients with type 2 diabetes," said Howard Foyt, M.D., Ph.D., FACP, vice president of clinical development. "Achievement of a statistically significant and clinically meaningful reduction in fasting plasma glucose levels in this patient population with once-a-day dosing of MB07803, coupled with demonstration of a safety and tolerability profile similar to placebo-treated patients, is a significant step forward for our FBPase inhibitor program. MB07803 was designed to have superior properties as compared to the first generation FBPase inhibitor and these early results suggest that we are on the right track. Although it is early in development and this study was not designed to compare the efficacy with other approaches, the results appear to be very promising and suggest that the FBPase approach may have the potential to achieve efficacy in line with current marketed therapies."

Paul Laikind, Ph.D., president and chief executive officer, stated, "We are very pleased with the results announced today. Not only does this represent an important milestone for the FBPase program, it is an important step forward in the strategic plan we outlined last year. We expect additional important key milestones over the course of the year including the presentation of the full data from this clinical trial, safety and efficacy data on our novel treatment for hyperlipidemia, MB07811, recommendation of one or more new metabolic disease therapies for clinical development and establishment of important strategic relationships to help insure the successful and timely development of our core and non-core assets. The results we announced today should assist us in establishing a collaboration for MB07803 with a strong partner thereby bolstering our efforts to develop an important new therapy for the millions of patients suffering with type 2 diabetes."

About Type 2 Diabetes:
Diabetes is a rapidly growing, worldwide health crisis. According to the International Diabetes Federation, in 2007, the number of patients suffering with diabetes worldwide reached over 245 million, with treatment and prevention costs reaching approximately $232 billion. Approximately 90% of patients with diabetes worldwide have type 2 diabetes. According to the American Diabetes Association, diabetes is the fastest growing disease in the U.S. In 2007, approximately 20 million Americans, or 7% of the U.S. population, were afflicted with diabetes, with costs associated with the disease reaching $174 billion.

Reminder: The Metabasis management team will host a conference call and live webcast to discuss first quarter 2008 financial results and Company updates at 1:30 p.m. Pacific Time (4:30 p.m. Eastern Time) on Thursday, May 1. Individuals interested in participating in the call may do so by dialing 800-322-2803 for domestic callers and 617-614-4925 for international callers. Please specify to the operator "Metabasis Therapeutics" when asked for a passcode. The conference call will be webcast live on Metabasis' website at www.mbasis.com under the "Investors" section, and will be archived there for 30 days following the call. Please connect to Metabasis' website several minutes prior to the start of the conference call to ensure adequate time for any software download that may be necessary.

About Metabasis (www.mbasis.com):
Metabasis is a biopharmaceutical company using its proprietary technologies, scientific expertise and unique capabilities for targeting the liver and liver pathways. The Company has established a broad pipeline of product candidates and advanced research programs targeting large markets with significant unmet needs. Metabasis' core area of focus is on the discovery and development of drug candidates to treat metabolic diseases such as hyperlipidemia and diabetes, among others. Although not a core focus of the Company, Metabasis has also discovered and developed drug candidates indicated for the treatment of liver diseases such as hepatitis and primary liver cancer, which it now intends to license or partner. All product candidates were developed internally using proprietary technologies.

Forward-Looking Statements:
Statements in this press release that are not strictly historical in nature constitute "forward-looking statements." Such statements include, but are not limited to, references to Metabasis' progress on its strategic goals and pursuit of its corporate objectives; the initiation, progress, completion and results of clinical trials for Metabasis' product candidates, including the expected results of clinical trials for MB07803 and MB07811; the potential efficacy and benefits of, and the potential market for, MB07803; the progress of Metabasis' discovery programs, including the expected advancement of certain programs into clinical development; potential collaborations for MB07803 and the establishment of other important strategic relationships; and other potentially value driving future milestones and events. Such forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause Metabasis' actual results to be materially different from historical results or from any results expressed or implied by such forward-looking statements. These factors include, but are not limited to, risks and uncertainties related to the progress and timing of clinical trials for Metabasis' product candidates; the fact that positive results from preclinical studies and early clinical trials does not necessarily mean later clinical trials will succeed; difficulties or delays in development, testing, obtaining regulatory approval, producing and marketing Metabasis' product candidates; serious adverse side effects or inadequate efficacy of, or serious adverse events related to, Metabasis' product candidates or proprietary technologies; the risk that Metabasis will not be able to build more value or retain rights for direct commercialization of its product candidates; Metabasis' dependence on its licensees and collaborators for the clinical development and registration of, as well as information relating to, certain of its product candidates; potential conflicts with collaborators that could delay or prevent the development or commercialization of Metabasis' product candidates; the scope and validity of intellectual property protection for Metabasis' product candidates, proprietary technologies and their uses; competition from other pharmaceutical or biotechnology companies; Metabasis' ability to obtain additional financing to support its operations; and other factors discussed in the "Risk Factors" section of Metabasis' Annual Report on Form 10-K for the fiscal year ended December 31, 2007 and in Metabasis' other filings with the Securities and Exchange Commission. All forward-looking statements are qualified in their entirety by this cautionary statement. Metabasis is providing this information as of the date of this release and does not undertake any obligation to update any forward-looking statements contained in this release as a result of new information, future events or otherwise.