Cubist Pharmaceuticals, Inc. (NASDAQ: CBST) today announced it will present new data from a phase 1 safety and pharmacokinetic study of fidaxomicin in children with Clostridium difficile-associated diarrhea (CDAD) at IDWeek 2014, being held October 8-12 in Philadelphia. These new data will be featured as a late-breaking oral presentation (LB-8, session #186) Saturday, October 11, 2014, at 10:30 a.m. EDT, given by Pam Sears, Vice President, Clinical Sciences, Cubist. The presentation will provide early insight into the safety, pharmacokinetic profile and efficacy of fidaxomicin in children who have CDAD.

“Children, especially those who have serious underlying medical conditions, are susceptible to Clostridium difficile-associated diarrhea, which can be very serious,” said Steven Gilman, Ph.D., Executive Vice President of Research and Development and Chief Scientific Officer of Cubist Pharmaceuticals. “These first data of fidaxomicin in children are important because they offer the first insights into a patient population that is typically excluded from Phase 3 clinical trials.”

This study of fidaxomicin enrolled 38 patients whose ages ranged from 11 months to 17 years, most of whom had complex underlying medical issues, including cancer (23.7%) and/or gastrointestinal disorders (78.9%). Adverse events observed in greater than two subjects included fever, vomiting, upper abdominal pain and C-difficile colitis. At least one adverse event was reported in 73.7% of patients. The majority of adverse events were categorized as mild (44.7%) or moderate (21.1%). Nine severe adverse events were observed during the course of the study and were not considered related to fidaxomicin. The pharmacokinetic profile seen in this study is similar to the profile shown in an adult population. Although not powered to assess efficacy, the clinical response observed in the study was 92.1%. The infections recurred in 28.6% of patients, all but one of whom had a history of recurrent CDAD.

“This study supports the further evaluation of fidaxomicin in children with C. difficile-associated diarrhea,” said Pam Sears. “As CDAD is most often observed in adults, there is much less information known about the pediatric presentation of the disease, and we are excited to present the results of our first study on the treatment of CDAD in children. We hope the results presented at IDWeek 2014 encourage ongoing dialogue and exchange on this important topic.”

In addition to this study, Cubist’s other presentations at IDWeek 2014 will feature the company’s portfolio of antibiotics for serious infections caused by multidrug-resistant bacteria. Data highlighted will offer insights into Cubist’s commitment to identifying treatments for drug-resistant Gram-positive and Gram-negative bacteria that cause serious infections.

Fidaxomicin is not currently approved for use in pediatric patients. Fidaxomicin is marketed in the U.S. as DIFICID® for the treatment of adult CDAD.

Indication and Important Safety Information

DIFICD Indication and Usage

  • DIFICID® (fidaxomicin) is indicated in adults (≥18 years of age) for treatment of Clostridium difficile-associated diarrhea (CDAD)
  • To reduce the development of drug-resistant bacteria, DIFICID should be used only to treat infections that are proven or strongly suspected to be caused by Clostridium difficile

DIFICD Important Safety Information

  • DIFICID should not be used for systemic infections.
  • Acute hypersensitivity reactions (angioedema, dyspnea, pruritus, and rash) have been reported. In the event of a severe reaction, discontinue DIFICID
  • Development of drug-resistant bacteria: Prescribing DIFICID in the absence of a proven or strongly suspected C. difficile infection is unlikely to provide benefit to the patient and increases the risk of the development of drug resistant bacteria
  • Adverse Reactions: The most common adverse reactions are nausea (11%), vomiting (7%), abdominal pain (6%), gastrointestinal hemorrhage (4%), anemia (2%), and neutropenia (2%)

About Cubist’s Commitment to Antibiotic R&D

Cubist has a growing commitment to global public health through its leadership in the discovery, development and commercialization of novel antibiotics to treat serious and potentially life-threatening infections caused by a broad range of increasingly drug-resistant bacteria. The Company hopes to deliver at least four new antibiotics in support of the Infectious Diseases Society of America (IDSA) goal of 10 new antibiotics by 2020. Cubist expects to invest approximately $400M USD in 2014 on antibacterial R&D and approximately 75% of its employee base is focused on the research, development, commercialization and support of antibiotics.

About Cubist

Cubist Pharmaceuticals, Inc. is a global biopharmaceutical company focused on the research, development, and commercialization of pharmaceutical products that address significant unmet medical needs in the acute care environment. Cubist is headquartered in Lexington, Massachusetts, with a central international office located in Zurich, Switzerland. Additional information can be found at Cubist’s web site at www.cubist.com. Also, connect with Cubist on Twitter @cubistbiopharma and @cubistcareers, LinkedIn, or YouTube.

About IDWeek 2014TM

IDWeek 2014TM is an annual meeting of the Infectious Diseases Society of America (IDSA), the Society for Healthcare Epidemiology of America (SHEA), the HIV Medicine Association (HIVMA) and the Pediatric Infectious Diseases Society (PIDS). With the theme “Advancing Science, Improving Care,” IDWeek features the latest science and bench-to-bedside approaches in prevention, diagnosis, treatment, and epidemiology of infectious diseases, including HIV, across the lifespan. IDWeek 2014 takes place October 8-12 at the Pennsylvania Convention Center in Philadelphia, Pennsylvania. The full name of the meeting is IDWeek 2014TM. For more information, visit www.idweek.org.

Forward Looking Statements

This press release contains forward-looking statements. Any statements contained herein which do not describe historical facts, including but not limited to, statements regarding: our intention to present data at IDWeek 2014 from a phase 1 study of fidaxomicin in children with CDAD, including our view that this study supports further evaluation of fidaxomicin in children with CDAD; our intention to present at IDWeek 2014 regarding our other antibiotics; our commitment to identifying treatments for drug-resistant bacteria that cause serious infections, including our commitment to global public health in this area; the level of our financial and personnel commitments towards antibiotic research, development and commercialization; our aspirations to achieve a portion of the IDSA goal of 10 new antibiotics by 2020; and the therapeutic potential of our products, are forward-looking statements which involve risks and uncertainties that could cause actual results to differ materially from those discussed in such forward-looking statements. Such risks and uncertainties include, among others: the fact that drug development involves a high degree of risk and a high rate of failure and success in early stage clinical trials does not mean that later stage trials will be successful; regulatory developments in the U.S. and other countries; the strength of, and our ability to successfully obtain, maintain and enforce intellectual property protecting our products; the fact that drug discovery and development is complex, time consuming, expensive and fraught with a high risk of failure; we are dependent on our ability to successfully work with, and the performance of, our third party clinical research organizations that we significantly rely on to help us conduct clinical trials; the timing and feasibility of any new clinical trials is dependent on our ability to successfully work with regulatory authorities, including the FDA on the design of the trials, among other things; technical difficulties or excessive costs relating to the manufacture or supply of our products, including our dependence on and the performance of our third party contract manufacturers that manufacture and supply our products on our behalf and those additional factors discussed in our most recent annual report on Form 10-K and subsequent quarterly reports on Form 10-Q filed with the Securities and Exchange Commission and available at www.sec.gov. We caution investors not to place considerable reliance on the forward-looking statements contained in this press release. These forward-looking statements speak only as of the date of this press release, and we undertake no obligation to update or revise any of these statements.

Cubist Pharmaceuticals, Inc.INVESTORS:Eileen C. McIntyre, 781-860-8533Vice President, Investor Relationseileen.mcintyre@cubist.comorMEDIA:Elizabeth Kalina, 781-860-8680Director, Product CommunicationsMobile: 312-545-8924elizabeth.kalina@cubist.com