Cubist Pharmaceuticals Announces New Phase III CIDECIN Data Presented At SIS Meeting; Presentation Includes Additional Data from Phase III Studies in cSST.

Business Editors and Health/Medical Writers

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LEXINGTON, Mass.--(BW HealthWire)--May 3, 2002

Cubist Pharmaceuticals, Inc. (Nasdaq: CBST) today announced the presentation of additional clinical data on its investigational antibiotic CIDECIN(R) (daptomycin for injection) at the Annual Meeting of the Surgical Infection Society (SIS) in Madrid, Spain. This is the first presentation of CIDECIN data at a scientific surgical meeting; surgeons would represent a large target market for CIDECIN, should it receive regulatory approval.

During a session entitled "Clinical Therapy: Antibiotics & Nutrition," Jacobus E.J. "Jake" Krige, MD, of the Department of Surgery Observatory at the University of Cape Town Medical School, Cape Town, South Africa, presented new data from two previously completed Phase III clinical trials evaluating the safety and efficacy of CIDECIN in the treatment of complicated skin and soft tissue (cSST) infections caused by Gram-positive bacteria. In both studies, CIDECIN achieved the required endpoint of statistical equivalence to the comparator agents. Patients were randomized to CIDECIN, 4 mg/kg once daily, or to comparator, where investigators had the choice of vancomycin, given twice daily, or a semi-synthetic penicillin (usually oxacillin) given four times daily. During his presentation, Dr. Krige highlighted three new subset data analyses from the two CIDECIN Phase III cSST clinical trials, referred to as Studies 9801 and 9901.

The first analysis detailed data from Study 9801, in which subjects treated with CIDECIN showed a trend towards faster mean time to defervescence (the return of elevated body temperature to normal)--one full day less than patients receiving the comparator agents. Table 1 summarizes these data. In addition, at the point in the study where 50% of patients had defervesced in each group, CIDECIN showed a statistically significant faster time to defervescence, 2.00 days versus 3.00 days for comparator (p value: 0.043 by log-rank analysis). Time to defervescence was a prospective secondary endpoint in this clinical trial. These data are consistent with clinical results on time to resolution of signs and symptoms and duration of intravenous therapy from Studies 9801 and 9901 previously presented at scientific meetings.

Table 1:  Time to Defervescence in Study 9801

                                   Daptomycin   Comparator    p Value

Patients Febrile at Baseline            74           72          n/a
Patients who Defervesced             64 (86%)     54 (75%)     0.08(a)
Mean Days to Defervescence             3.26         4.26       0.06(b)

(a) p value by Chi-Square analysis
(b) p value by t-test analysis

The second analysis detailed clinical success rates from all patients in Studies 9801 and 9901 with surgical infections including abscesses and wound infections. These data are summarized in Table 2 and have been analyzed for the surgical community, as they are representative of typical complicated skin and soft tissue infections treated by surgeons.

Table 2:  Outcome by Specific Diagnosis in Studies 9801/9901

                          n      Daptomycin      n      Comparator
Abscesses                110     100 (91%)       99       84 (85%)
Wound Infections(a)      155     134 (87%)      188      162 (86%)

n = number of patients

(a) Wound Infections included trauma, surgical incisions, bite and
foreign body

The third analysis focused on the need for dosage adjustments in subjects in Study 9801 receiving the comparator agent vancomycin. Forty-seven percent of the 153 subjects treated with vancomycin were determined by investigators to require dosage adjustments while on therapy for reasons including decreased renal function and observed blood levels outside the standard vancomycin therapeutic range. No subjects receiving daptomycin needed adjustments to the once-daily dosing regimen while on therapy.

Francis P. Tally, MD, Executive Vice President, Scientific Affairs and Chief Scientific Officer of Cubist commented: "In previous studies, CIDECIN has demonstrated rapid bactericidal activity in both in vitro and animal models. Although the U.S. Food & Drug Administration and other regulatory bodies will determine whether CIDECIN is safe and effective in the treatment of cSST infections, we continue to be encouraged by data from our CIDECIN cSST Phase III studies suggesting trends in faster time to defervescence, quicker resolution of signs and symptoms and fewer days of intravenous therapy to achieve clinical success."

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.