In the Pipeline:
Gram-negative CXA-201

Gram-negative CXA-201^**

In December 2009, Cubist acquired Calixa Therapeutics, a biopharmaceutical company focused on the development of novel antibiotics addressing the expanding problem of certain multi-drug resistant Gram-negative pathogens. This acquisition fits well with our strategic goal of bringing in later stage acute care assets to leverage our acute care development, regulatory and commercial infrastructure and expertise.

Importantly, we view this as an acquisition which has a potential to benefit seriously ill patients and create considerable long-term value for shareholders of Cubist. We are extremely excited about the potential of Calixa's Phase 2 CXA-201 antibiotic candidate, which is being developed as a first line intravenous therapy for the treatment of certain serious Gram-negative bacterial infections, including those caused by multi-drug resistant Pseudomonas aeruginosa. The acquisition gives Cubist the exclusive rights to develop and commercialize Calixa's lead compound, CXA‐201, and other products that incorporate the novel anti‐pseudomonal cephalosporin, CXA‐101, in all territories of the world except select Asia‐Pacific and Middle East territories. Assuming successful clinical development, Cubist expects to file a New Drug Application (NDA) for CXA‐201 in complicated urinary tract infections (cUTI) and complicated intra-abdominal infections (cIAI) in 2H13. The company also will be initiating studies of CXA‐201 to support an indication in nosocomial pneumonia.

We see a potential commercial opportunity for CXA-201 of approximately $1 billion in the U.S. and EU combined.

Pseudomonas aeruginosa is among the most frequently isolated Gram-negative organisms in intra-abdominal infections, urinary tract infections, pneumonia, blood stream and wound infections.

Besides its intrinsic resistance to a number of widely used antibiotics, Pseudomonas has acquired additional resistance from genetic mutations acquired from other organisms. These resistant strains have become more prevalent over the past decade and resistant rates of Pseudomonas to cephalosporins, amino glycosides, carbapenems and quinolones now range between 20 and 30 percent in hospitals in the U.S.

We view this unmet medical need as very similar to what was occurring with MRSA - Methicillin-resistant Staph aureus as we began in earnest the development of CUBICIN in the late 1990's. Despite growing concerns about multi-drug resistant Pseudomonas strains, few new anti-Pseudomonal drugs are currently in clinical development.

Acquisition of Calixa Therapeutics

• Press Releases
  • Cubist Enrolls First Patient in CXA-201 Phase 2 Study in Complicated Intra-Abdominal Infections (6/30/10)
  • Cubist Announces All Objectives Met in Phase 2 CXA-101 Complicated Urinary Tract Infections Study (6/29/10)
• Aquisition Information
  • December 14, 2009 Conference Call Webcast
  • FAQ
  • Cubist Completes Acquisition Of Calixa Therapeutics (12/16/09)
  • Cubist to Acquire Calixa Therapeutics (12/14/09)