Cubist Pharmaceuticals Initiates Phase 2 Trial in Europe for Therapy to Reduce Blood Loss During Surgery in High Risk Patients

LEXINGTON, Mass.--(Business Wire)--
Cubist Pharmaceuticals, Inc. (Nasdaq: CBST), a leading acute care therapeutics
company, announced today that it has begun dosing in the CONSERV-2 clinical
trial with ecallantide. CONSERV-2, being conducted in Europe, is a Phase 2 trial
that will investigate ecallantide`s effect on surgical blood loss volume in
cardiac surgery patients who are on cardiopulmonary bypass and are at a high
risk of bleeding. The trial is expected to enroll 300 subjects.

Ecallantide is a potent inhibitor of plasma kallikrein, and CONSERV-2 will
evaluate the effects of plasma kallikrein inhibition in the trial population.
Surgical environments, such as those involving the trial population, are
associated with the activation of plasma kallikrein and subsequent activation of
coagulation, fibrinolytic, and inflammatory cascades, which likely contribute to
blood loss and blood transfusion requirements in the perioperative setting.

"The dosing of patients in the CONSERV-2 trial represents another important
milestone in the continued evaluation of ecallantide for the reduction of blood
loss during on-pump cardiac surgery, an area of significant unmet medical need.
We remain on track for a mid-2010 end-of-phase 2 meeting with the FDA, and we
anticipate that the results of this trial and the ongoing CONSERV-1 trial will
provide meaningful insights into the optimal design of subsequent Phase 3
trials," said Santosh Vetticaden, PhD, MD, Senior Vice President, Clinical
Development and Chief Medical Officer.

"This represents another important milestone for our growing pipeline of novel
acute care therapeutics" said Steve Gilman, PhD, Chief Scientific Officer and
Senior Vice President, Discovery and Nonclinical Development.

In April 2008, Cubist announced an exclusive North American and European license
and collaboration agreement with Dyax Corp. (NASDAQ: DYAX) for the development
and commercialization of the intravenous formulation of ecallantide for surgical
indications. The first indication being sought by Cubist for ecallantide is the
reduction of blood loss during on-pump cardiac surgery.

About Cubist

Cubist Pharmaceuticals, Inc. is a biopharmaceutical company focused on the
research, development, and commercialization of pharmaceutical products that
address unmet medical needs in the acute care environment. In the U.S., Cubist
markets CUBICIN® (daptomycin for injection), the first antibiotic in a new class
of anti-infectives called lipopeptides. In July 2008, Cubist began promoting
MERREM® I.V. (meropenem for injection) in the United States. MERREM is an
established broad spectrum antibiotic developed by AstraZeneca. The Cubist
product pipeline includes ecallantide, a recombinant human protein in Phase 2
clinical trials - CONSERV-1 and CONSERV-2 - for the reductionof blood loss
during on-pump cardiac surgery, and two Phase 1 programs that address unmet
medical needs, one in CDAD (Clostridium difficile-associated diarrhea) and the
other in multi-drug resistant (MDR) Gram-negative infections. In addition, the
Company, in collaboration with Alnylam Pharmaceuticals, Inc. (Cambridge, MA),
has a pre-IND and a Phase 2 program underway in novel treatments for respiratory
syncytial virus infections using Alnylam`s RNA-interference technology. Cubist
is headquartered in Lexington, MA. Additional information can be found at
Cubist`s web site at www.cubist.com.

Cubist Safe Harbor Statement

This press release contains forward-looking statements regarding the development
of ecallantide for the reduction of blood loss volume during on-pump cardiac
surgery. There are many factors that could cause actual results to differ
materially from those in these forward-looking statements. These factors include
the following: (i) ecallantide may not show sufficient therapeutic effect or an
acceptable safety profile in clinical trials; (ii) clinical trials of
ecallantide may not be successful or conducted in a timely manner; (iii) the
commercial market for the use of ecallantide for the reduction of blood loss
volume during on-pump cardiac surgery may not be as large as Cubist anticipates;
(iv) others may develop technologies or products superior to ecallantide to
treat blood loss during on-pump cardiac surgery; (v) technical difficulties or
excessive costs relating to the manufacture of ecallantide; (vi) Cubist or Dyax
Corp., from which Cubist licensed its rights to ecallantide, may not be able to
maintain and enforce the intellectual property protecting ecallantide; and (vii)
other unanticipated or unexpected risks that may be encountered with respect to
the development or manufacture of ecallantide. 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 periodic filings
with the Securities and Exchange Commission, including those factors discussed
under the caption "Risk Factors" in such filings. These statements speak only as
of the date of this release, and Cubist undertakes no obligation to update or
revise these statements, except as may be required by law.

Cubist and CUBICIN are registered trademarks of Cubist Pharmaceuticals, Inc.

AstraZeneca and MERREM are registered trademarks of the AstraZeneca group of
companies.

Cubist Pharmaceuticals, Inc.
Eileen C. McIntyre, 781-860-8533
Senior Director, Corporate Communications
eileen.mcintyre@cubist.com
or
Weber Shandwick
Tara Murphy, 617-520-7045
tmurphy@webershandwick.com

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