Cubist Pharmaceuticals Launches CORE, a CUBICIN U.S. Clinical Outcomes Registry.

Business Editors/Health/Medical Writers

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LEXINGTON, Mass.--(BUSINESS WIRE)--March 17, 2004

CORE Program to Provide Valuable Data to Physicians Treating Serious Gram-Positive Infections

Cubist Pharmaceuticals, Inc. (Nasdaq: CBST) today launched a registry program branded CORE(SM), or Cubicin Outcomes Registry & Experience. Cubicin(TM) (daptomycin for injection), a first in class bactericidal antibiotic, was launched in the U.S. by Cubist in late 2003 for the treatment of complicated skin and skin structure infections caused by certain Gram-positive organisms. CUBICIN is currently the only once-daily bactericidal antibiotic proven effective against both methicillin-resistant and methicillin-susceptible Staphylococcus aureus (MRSA and MSSA).

Debra Goff, PharmD, Clinical Associate Professor and Infectious Diseases Specialist at The Ohio State University Medical Center, commented on the launch of CORE: "Over the past several years, mortality rates and costs associated with the treatment of serious Gram-positive infections have risen dramatically, particularly as a result of infections caused by resistant organisms. With the creation of CORE, Cubist is helping supply valuable data to the clinical community--data that not only tracks relationships between patient demographics and clinical characteristics, but also provides outcomes data and allows sites to learn from the experiences of other participants in CORE. More importantly, CORE is expected to provide comparative data that may improve patient management strategies and quality improvement initiatives."

CORE is a retrospective, longitudinal, multicenter registry program designed to collect information on patients who have received CUBICIN therapy. Cubist expects to enroll 40 sites in the U.S. by the end of 2004. By facilitating the benchmarking of regional data against national trends, the registry is intended to improve information flow on the standards of care for patients treated for serious Gram-positive bacterial infections. Data from the registry will be published as it becomes available.

For more information on the CORE program, contact Westat Clinical Trials at [phone]. The CORE program complies with all applicable HIPAA requirements.

To reduce the development of drug-resistant bacteria and maintain the effectiveness of CUBICIN and other antibacterial drugs, CUBICIN should be used only to treat or prevent infections that are proven or strongly

suspected to be caused by susceptible bacteria. Patients receiving CUBICIN should be observed for the development of muscle pain or weakness and have creatine phosphokinase (CPK) levels monitored weekly if unexplained symptoms develop. CUBICIN is not indicated for the treatment of pneumonia. The most commonly reported adverse events in the cSSSI clinical trials in adults were constipation, nausea and headache.

CUBICIN is indicated for the treatment of complicated skin and skin structure infections caused by susceptible strains of the following Gram-positive microorganisms: Staphylococcus aureus (including methicillin-resistant strains), Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus dysgalactiae subsp. equisimilis and Enterococcus faecalis (vancomycin-susceptible strains only).

For full prescribing information, visit www.Cubicin.com. Cubicin is a trademark and CORE is a service mark of Cubist Pharmaceuticals, Inc.

About Cubist

Cubist Pharmaceuticals, Inc. is a biopharmaceutical company focused on the research, development and commercialization of drugs that meet significant unmet medical needs. Since its founding in 1992, Cubist has been exclusively focused on exploiting business and product opportunities in the antiinfective marketplace. In the U.S., Cubist markets Cubicin(TM) (daptomycin for injection), the first antibiotic in a new class of antiinfectives called lipopeptides, for the indication of complicated skin and skin structure infections caused by Gram-positive bacteria. CUBICIN is currently the only once-daily bactericidal antibiotic approved in the U.S. with activity against both methicillin-susceptible and methicillin-resistant Staphylococcus aureus (MSSA and MRSA). Cubist's pre-clinical pipeline includes an oral version of ceftriaxone (OCTX), a broad-spectrum cephalosporin antibiotic, and other novel members of the lipopeptide class. Cubist is headquartered in Lexington, MA.

Cubist Safe Harbor 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, and such statements 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 Cubist. These factors include, but are not limited to: (i) the level of acceptance of CUBICIN by physicians, patients, third-party payors, and the medical community generally; (ii) Cubist's ability to continue to develop, secure additional regulatory approvals for, and successfully market, CUBICIN; (iii) Cubist's ability to manufacture CUBICIN on a commercial scale; (iv) commercialization of products that are competitive with CUBICIN; (v) Cubist's ability to further identify, develop, and achieve commercial success for new products and technologies; (vi) Cubist's ability to establish and maintain successful manufacturing, sales and marketing, distribution, and development collaborations; (vii) legislative or regulatory changes adversely affecting Cubist or the biopharmaceutical industry; (viii) Cubist's ability to protect its intellectual property and proprietary technologies; and (ix) Cubist's ability to finance its operations. Additional factors that could cause actual results to differ materially from those projected or suggested in any forward-looking statements are contained in Cubist's recent filings with the Securities and Exchange Commission, including those factors discussed under the caption "Risk Factors" in such filings.

Additional information can be found at Cubist's web site at www.cubist.com