Cubist Pharmaceuticals Announces New Cidecin-R- Data Presented at ECCMID 2002 Meeting.

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LEXINGTON, Mass.--(BW HeatlhWire)--April 26, 2002

Presentations Include Data from Phase II Studies in VRE and cUTI and

New In vitro Activity Data

Cubist Pharmaceuticals, Inc. (Nasdaq: CBST) today announced the presentation of new clinical and in vitro data on its investigational antibiotic Cidecin(R) (daptomycin for injection) at the 12th European Congress of Clinical Microbiology and Infectious Diseases (ECCMID) in Milan, Italy.

Francis P. Tally, MD, Executive Vice President, Scientific Affairs and Chief Scientific Officer of Cubist commented on the presentations: "We are very pleased with both the quality and quantity of data related to CIDECIN at this year's ECCMID meeting. As we anticipate a 2003 launch of CIDECIN, data such as these represent a key component of our planned marketing strategy. Should we gain U.S. Food & Drug Administration approval, we will focus on package insert development through further clinical registration studies and through scientific publication of both clinical and microbiologic data."

In a poster presentation, David R. Snydman, MD, of the Tufts - New England Medical Center (T-NEMC), reported results from a completed Phase II clinical trial investigating the use of CIDECIN in patients with febrile neutropenia (immunocompromised patients with fever) and infections caused by vancomycin-resistant Enterococci faecium (VREF). VREF infections are associated with high mortality rates. In the study, patients had underlying acute myeloid leukemia or had recently undergone a bone marrow transplant. All had VRE bacteremia (infection of the bloodstream). Patients received CIDECIN in a variety of dosing regimens and were compared to historical controls from T-NEMC. Importantly, in the study, CIDECIN treatment was associated with good clinical and microbiologic outcome compared to the historical control, with survival rates of 50% (4/8) versus 22% (2/9) and clinical or microbiological cure rates of 55% (5/9) versus 33% (3/9), respectively (see Table 1). Cubist is currently investigating the safety and efficacy of CIDECIN in a Phase III VRE infection trial.

Table 1: Clinical and Microbiologic Success and Survival Rates in
Phase II VREF Study

                                  Daptomycin             Control

Clinical or Micro Cure            5/9 (55%)             3/9 (33%)

Survival                          4/8 (50%)             2/9 (22%)

During a Continuing Medical Education (CME) symposium during the ECCMID meeting, Jan Verhoef, MD, Ph.D., of the University Medical Centre Utrecht, for the first time presented data sets from a Phase II clinical trial examining the efficacy of CIDECIN in the treatment of complicated urinary tract infections (cUTIs) caused by Gram-positive pathogens (see Table 2). In the study, factors defining cUTI included urinary tract surgery within the prior three months, post-voiding residual volume, neurogenic bladder, renal, urethral or bladder calculi or urinary tract obstruction. The trial achieved its goal of demonstrating no differences between the microbiologic and clinical cure rates for CIDECIN versus the comparator agent across all patient populations.

Table 2: Clinical Results from Phase II cUTI Study: Daptomycin Versus
Ciprofloxacin

                            Daptomycin     Ciprofloxacin

Clinical Success Rate       29/31 (94%)     28/30 (93%)

Microbiologic
Eradication Rate            24/29 (83%)     18/18 (100%)

Clinical Relapse             1/29 (3%)       1/17 (6%)

During his presentation, Dr. Verhoef also summarized in vitro data from a recently published manuscript by Fuchs et al. in the Journal of Antimicrobial Chemotherapy (2002) 49, 467-470. In the study, the bactericidal in vitro activity of daptomycin was compared to vancomycin during a time-kill experiment against both methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA). Of the drugs tested, daptomycin was bactericidal against all strains and had the most rapid cidal activity (see Table 3).

Table 3:  In vitro Activity of Daptomycin Against Staphylococcus

                Bactericidal Activity (greater than 99.9%kill)(a)

                       MSSA                            MRSA
           Strains Killed    Mean Time    Strains Killed    Mean Time

Daptomycin      100%         2.3 hours        100%          3.0 hours
Vancomycin       67%         12.0 hours        60%          12.0 hours

(a) greater than 3 log reduction in colony counts within 24 hours

Also during the ECCMID conference, three posters were presented by Focus Technologies of Herndon, Virginia, examining the in vitro activity of CIDECIN against European isolates of both susceptible and drug-resistant bacteria, including enterococci, staphylococci and streptococci. The intent of the studies was to assess the current activity of CIDECIN against these clinically important Gram-positive bacteria and establish a baseline by which to monitor future studies. In the poster focused on enterococci, resistance rates varied from 0% in Switzerland and Scandinavia, to 61% in Italy. Against these isolates, CIDECIN showed consistent in vitro activity against enterococci regardless of resistance to other antimicrobials, including multidrug-resistant (MDR) isolates. In the poster focused on staphylococcus, rates of resistance to other antimicrobials ranged from 0% in the Netherlands to 37% in Portugal. In this study, CIDECIN demonstrated equivalent or superior activity compared to the other directed-spectrum agents, linezolid and quinupristin-dalfopristin, against both oxacillin-susceptible and -resistant isolates and MDR isolates of both Staphylococcus aureus and coagulase-negative staphylococci. In the third poster, focused on streptococci, rates of resistance to other antimicrobials ranged from 0% in the Netherlands to 21% in Portugal. CIDECIN demonstrated potent activity against both Streptococcus pneumoniae and Streptococcus agalactiae, including those resistant to other antimicrobial classes and MDR isolates.

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.