Ramoplanin Highly Active In Vivo Against Clostridium difficile Infections.

Business Editors/Health/Medical Writers

GLASGOW, Scotland & WALTHAM, Mass.--(BUSINESS WIRE)--May 12, 2003

Animal Model Demonstrates Increased Potency of Ramoplanin

Compared to Current Therapies

Researchers at the 13th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID), being held in Glasgow, Scotland, May 10-13, 2003, are presenting compelling data on the in vivo activity of Ramoplanin in a hamster model for Clostridium difficile-associated diarrhea (CDAD) or colitis. Ramoplanin is a novel glycolipodepsipeptide antibiotic under development by Genome Therapeutics (Nasdaq: GENE), currently in a Phase III trial for the prevention of bloodstream infections caused by vancomycin-resistant enterococci and in a Phase II trial for the treatment of CDAD.

In a poster presentation by Daniel Jabes, Ph.D., on May 13, 2003 at ECCMID entitled "Efficacy of Ramoplanin in the Hamster Model of C. difficile Associated Colitis," Ramoplanin is shown to be significantly more potent than vancomycin in treating hamsters with antibiotic-associated diarrhea or colitis, such as CDAD.

"The data presented by Dr. Jabes and her team have provided us with additional evidence of the potential value of Ramoplanin in treating C. difficile-associated diarrhea, a problem that affects an estimated 400,000 patients a year in U.S. hospitals," stated Steven M. Rauscher, Chairman, Chief Executive Officer and President of Genome Therapeutics. "As the Phase II trial of Ramoplanin for CDAD continues, we anticipate providing clinical data on the role of Ramoplanin in treating this potentially serious form of infectious diarrhea later this year."

About the Study

Dr. Jabes and her team from Vicuron Pharmaceuticals, formerly Biosearch Italia, induced antibiotic-related diarrhea in hamsters in order to compare Ramoplanin to vancomycin and metronidazole, the currently used treatments for CDAD. In the hamster model, survival is the primary endpoint, as C. difficile infections in hamsters are often fatal. In the first experiment, the scientists used clindamycin, an antibiotic commonly associated with antibiotic-related colitis, to trigger diarrhea in the hamsters. The resulting condition was associated with a 100% mortality rate in untreated animals, and toxin A, produced by C. difficile, was present in all untreated animals. Subsequently, a group of these hamsters received either Ramoplanin or vancomycin. Ramoplanin-treated animals had an 80% survival rate, while vancomycin-treated animals had only a 20% survival rate (P less than 0.05). In another experiment, hamsters were challenged by C difficile delivered orally, followed by a dose of clindamycin to create an even more severe test of the effects of Ramoplanin, vancomycin and metronidazole. Ramoplanin was the only agent associated with any survival (20%) in this experiment as no hamsters treated with metronidazole or vancomycin survived to the end of the experimental period. The study also evaluated the compounds' propensities to induce antibiotic-related diarrhea, a condition often associated with oral antibiotic use. Ramoplanin showed a lower potential to cause the condition, demonstrating Ramoplanin's potentially less disruptive impact on the normal gastrointestinal (GI) bacterial flora. The authors anticipate providing more detail of their work in upcoming peer-reviewed journal articles.

"Ramoplanin was able to prolong survival in cases of severe C. difficile colitis in hamsters, and was also more efficacious than vancomycin and metronidazole, the currently used medications for CDAD, in preventing mortality," stated Dr. Jabes, senior author on the poster. "The ability of Ramoplanin to successfully treat experimental cases of antibiotic-induced diarrhea supports the current clinical investigation of the novel antibiotic in treating C. difficile-associated diarrhea."

About Clostridium difficile-Associated Diarrhea

There are approximately 400,000 cases of Clostridium difficile-associated diarrhea a year reported in U.S. hospitals. One study has demonstrated that as many as 20% of hospital patients are colonized with C. difficile either prior to or during admission. Because it is a spore-forming bacteria, C. difficile can persist in the environment and be readily spread from person to person, especially in hospitals and nursing homes. Under certain conditions, such as extended antibiotic therapy and gastrointestinal surgery, C. difficile can colonize the gut and release toxins, leading to bowel inflammation and severe diarrhea. Serious cases can occur and involve the development of fulminant colitis (severe inflammation of the colon); such occurrences can be life-threatening, especially in elder or immunocompromised populations. Current therapies for the treatment of CDAD include metronidazole and vancomycin, although these agents are associated with a 15-20% relapse rate.

About Ramoplanin

Ramoplanin is an investigational new drug in clinical development by Genome Therapeutics. A novel product of microbial fermentation first discovered by Vicuron Pharmaceuticals, formerly Biosearch Italia, Ramoplanin is a member of a new class of antibiotics known as glycolipodepsipeptides. Genome Therapeutics has acquired development and commercialization rights to Ramoplanin for North America from Vicuron Pharmaceuticals. Ramoplanin has potent in vitro bactericidal activity targeted against Gram-positive bacteria, including many antibiotic resistant strains such as vancomycin-resistant enterococci (VRE), methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Staphylococcus aureus (VRSA). It is also bactericidal in vitro against Clostridium difficile. Because it is not absorbed systemically from the GI tract following oral dosing and exerts its bactericidal activity in the GI tract, Ramoplanin represents a potential new concept for managing certain pathogens commonly found in the hospital and carried in patients' GI tracts. In a Phase II study, Ramoplanin was shown to be highly effective at decolonizing patients carrying VRE in their GI tracts. Ramoplanin, which has Fast Track status from the FDA, is currently being studied for two indications: a Phase III clinical trial for the prevention of VRE bloodstream infections and a Phase II study for treating Clostridium difficile-associated diarrhea.

About Genome Therapeutics

Genome Therapeutics is a biopharmaceutical company focused on the discovery and development of pharmaceutical and diagnostics products. The Company's lead product candidate, Ramoplanin, is currently under Phase III investigation for the prevention of bloodstream infections caused by vancomycin-resistant enterococci (VRE), and under Phase II investigation for the treatment of Clostridium difficile-associated diarrhea (CDAD). Genome Therapeutics' biopharmaceutical business includes a robust internal drug discovery program in the area of anti-infectives, and seven major product discovery alliances with several pharmaceutical companies including Amgen, AstraZeneca, bioMerieux, Schering-Plough and Wyeth.

This news release may contain forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements represent our management's judgment regarding future events. Forward-looking statements typically are identified by use of terms such as "may," "will," "should," "plan," "expect," "intend," "anticipate," "estimate," and similar words, although some forward-looking statements are expressed differently. We do not plan to update these forward- looking statements. You should be aware that our actual results could differ materially from those contained in the forward- looking statements due to a number of risks affecting our business. These risk factors include risks related to our lead product candidate, Ramoplanin, such as (i) our inability to obtain regulatory approval to commercialize Ramoplanin due to negative, inconclusive or insufficient clinical data and (ii) delays in the progress of our clinical trials for Ramoplanin, and increased cost, due to the pace of enrollment of patients in the trials or fluctuations in the infection rate of enrolled patients. We are also subject to risks related to our inability or the inability of our alliance partners to (i) successfully develop products based on our genomics information, (ii) obtain the necessary regulatory approval for such products, (iii) effectively commercialize any products developed before our competitors are able to commercialize competing products or (iv) obtain and enforce intellectual property rights. In addition, we are subject to the risk factors set forth in Exhibit 99.1 to the Company's Annual Report on Form 10-K for the year ended December 31, 2002 and those set forth in other filings that we may make with the Securities and Exchange Commission from time to time.