Cubist PharmaCubist Pharmaceuticals, Inc a leading acute care therapeutics company, announced the signing of a definitive agreement under which Cubist has agreed to acquire privately held Calixa Therapeutics Inc, a biopharmaceutical company focused on the development of novel antibiotics that address the expanding problem of multi-drug resistant Gram-negative pathogens.

The Boards of Directors of each company have unanimously approved the agreement. Subject to obtaining requisite consents and other conditions, the acquisition is expected to close in the fourth quarter of 2009.

Calixa's lead compound, CXA-201 is an intravenously administered combination of Calixa's novel anti-pseudomonal cephalosporin CXA-101, which is currently in phase-2 clinical trials for cUTI, and the b-lactamase inhibitor tazobactam. Cubist would obtain Calixa's rights to develop and commercialize CXA-201, and other products that incorporate CXA-101 (previously FR264205), which Calixa acquired from Astellas Pharma Inc. Calixa has such rights in all territories of the world except select Asia-Pacific territories.

CXA-201 is being developed as a first-line intravenous therapy for the treatment of certain serious Gram-negative bacterial infections in the hospital, including those caused by multi-drug resistant P. aeruginosa. Its demonstrated potency against P. aeruginosa would give CXA-201 a highly differentiated profile versus marketed antibiotics. Cubist anticipates advancing the program for cUTI and cIAI in the first half of 2010. The next study in the cUTI programme would take into consideration the results of the ongoing cUTI trial with CXA-101 and, in addition, a phase-2 trial of CXA-201 for cIAI would be planned for the first half of 2010. Cubist also would expect to begin clinical studies of CXA-201 for the nosocomial pneumonia indication in the second half of 2010. Assuming successful development, Cubist would expect to file a New Drug Application for CXA-201 in the second half of 2013.

Pursuant to the terms of the agreement, on closing, Cubist would pay to the Calixa stockholders US$ 92.5 million in cash, subject to certain adjustments, and Calixa would become a wholly-owned subsidiary of Cubist. Cubist also would be required to make potential payments to the Calixa stockholders of up to US$ 310 million upon achieving certain development, regulatory, and commercial milestones related to products which incorporate CXA-101. No financing would be necessary to complete the acquisition of Calixa or to fund the development of Calixa's product candidates.

Cubist president and CEO Michael Bonney said, "We are excited about the opportunity to add CXA-201 to our clinical pipeline. If successfully developed and launched, we believe that CXA-201 would be a potent weapon in the treatment of serious infections caused by multi-drug-resistant strains of the Gram negative pathogen Pseudomonas aeruginosa, playing a role similar to our Gram positive therapy Cubicin (daptomycin for injection) for the treatment of complicated skin infections and bacteremia caused by MRSA. We believe Cubist is ideally positioned to develop and commercialize this novel antibiotic that, assuming success, will provide physicians with a critically needed new weapon to treat certain serious infections caused by multi-drug-resistant Gram-negative pathogens, including those caused by Pseudomonas aeruginosa."

"We are delighted to be entering into this transaction with Cubist," added Dennis Podlesak, Calixa's chief executive officer. "Cubist has a proven track record of success in developing and commercializing anti-infective products, as highlighted by the considerable success of Cubicin, and we have great confidence in their ability to optimize the therapeutic and commercial potential of the Calixa portfolio."

Calixa Therapeutics is a privately-held biopharmaceutical company focused on the development of a novel cephalosporin to address the expanding problem of multi-drug resistant organisms.

Cubist Pharma is a biopharmaceutical company focused on the research, development, and commercialization of pharmaceutical products that address unmet medical needs in the acute care environment.