Cubist Pharmaceuticals Announces Plan to File CIDECIN NDA by End of 2002; FDA Indicates that Proposed NDA Package is Acceptable for Filing.

Business/Technology Editors & Health/Medical Writers

BIOWIRE2K

LEXINGTON, Mass.--(BW HealthWire)--March 7, 2002

Cubist Pharmaceuticals, Inc. (Nasdaq: CBST) today announced its intention to proceed as planned with a 2002 New Drug Application (NDA) filing to the U.S. Food & Drug Administration (FDA) for its investigational antibiotic Cidecin(R) (daptomycin for injection) for the indication of complicated skin and soft tissue (cSST) infections involving both susceptible and resistant Gram-positive organisms. This decision comes following the receipt of correspondence from the FDA indicating that the CIDECIN NDA package as proposed would be acceptable for filing.

CIDECIN is the first in a new class of antibiotics called lipopeptides. Its safety and efficacy are currently being evaluated in multiple Phase III studies at Cubist. Cubist has previously announced results from two pivotal Phase III clinical trials assessing the safety and efficacy of CIDECIN in the treatment of cSST infections. The primary endpoint of demonstrating equivalency to comparator agents was achieved in both studies. In addition, the incidence of total adverse events in the studies was similar in both the CIDECIN and comparator agent arms.

Scott M. Rocklage, Ph.D., Chairman and CEO of Cubist commented on the news. "We are extremely pleased to be in a position to file the U.S. NDA on CIDECIN by the end of 2002. We are also encouraged by data emerging from ongoing market research assessing physician and formulary acceptance of CIDECIN with the existing data package. Based on our current timeline and market feedback, we are now preparing for the U.S. launch of CIDECIN during 2003, assuming final FDA approval."

Cubist has also announced preliminary results from the first of two pivotal, Phase III trials investigating the safety and efficacy of CIDECIN in the treatment of community-acquired pneumonia requiring hospitalization (the CAP1 trial). According to these preliminary data, the primary endpoint of demonstrating non-inferiority to an active comparator agent was not achieved in the overall international study. However, in the North American and Western European populations, the endpoint was achieved in the intent-to-treat and clinically evaluable cohorts. Importantly, the adverse event profiles were similar between the Cidecin and comparator study arms. Enrollment in the second trial, CAP2, was halted in mid-January 2002 pending further review of the CAP1 data.

Cubist also announced today a complete re-analysis of the data from the CAP1 study. As a result of internal data analysis, the Company now believes a thorough review of the data by independent medical consultants is warranted to help clarify the CAP1 clinical trial results.

In addition to the clinical and microbiologic data intended to be included in this year's CIDECIN NDA filing, Cubist is conducting additional clinical studies on CIDECIN. A Phase III study is currently ongoing investigating the safety and efficacy of CIDECIN in the treatment of vancomycin-resistant Enterococcal infections (the VRE study) and a Phase III study is poised to begin evaluating CIDECIN's use in the treatment of endocarditis and bacteremia (infections of the heart valves and bloodstream, respectively). These studies are being conducted for future package insert development, should CIDECIN receive approval for the initial indications sought.

Cubist Pharmaceuticals, Inc. is focused on becoming a global leader in the research, development and commercialization of novel antimicrobial drugs to combat serious and life-threatening bacterial and fungal infections. Cubist is evaluating the safety and efficacy of Cidecin(R) (daptomycin for injection) in the EDGE(TM) (Evaluation of Daptomycin against Gram-positive Entities) clinical trial program and has broadened its pipeline to include multiple pre-clinical drug candidates. The Company is engaged in strategic partnerships with Novartis Pharma AG for the discovery and development of novel antiinfectives and with Gilead Sciences for the commercialization of daptomycin in Europe. Cubist is headquartered in Lexington, MA and has operations in Vancouver, BC, Canada and Slough, UK.

Cubist Safeharbor Statement

Statements contained herein that are not historical fact may be forward-looking statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, that are subject to a variety of risks and uncertainties. There are a number of important factors that could cause actual results to differ materially from those projected or suggested in any forward-looking statements made by the Company. These factors include, but are not limited to: (i) the Company's ability to successfully complete product research and development, including pre-clinical and clinical studies and commercialization; (ii) the Company's ability to obtain required governmental approvals; (iii) the Company's ability to attract and/or maintain manufacturing, sales, distribution and marketing partners; and (iv) the Company's ability to develop and commercialize its products before its competitors. Additional factors that would cause actual results to differ materially from those projected or suggested in any forward-looking statements are contained in the Company's filings with the Securities and Exchange Commission, including those factors discussed under the caption "Risk Factors" in the Company's recent SEC filings.

Cidecin(R) (daptomycin for injection) and EDGE(TM) are trademarks of Cubist Pharmaceuticals, Inc.

Additional information can be found at the Company's web site at www.cubist.com or at www.noonanrusso.com.