Kosan Biosciences Incorporated announced that Pfizer Inc. has initiated a phase I clinical trial of motilin receptor agonist PF-04548043, formerly KOS-2187, a selective and potent motilin receptor agonist being developed for the treatment of gastroesophageal reflux disease (GERD) and potentially other gastrointestinal (GI) disorders.

The phase I clinical trial is designed to test the safety, tolerability and pharmacokinetics of PF-04548043 in healthy subjects. In December 2006, Kosan and Pfizer established a worldwide license agreement for Kosan's motilin agonist program, including KOS-2187 and related compounds, in a transaction potentially valued at $250 million for the successful development and commercialisation of PF-04548043 for one indication as well as royalties on worldwide sales.

"Kosan today has four advancing clinical programmes, underscoring the increasing value of our development pipeline," said Robert G Johnson, Jr, PhD., Kosan's president and CEO. "Consistent with Kosan's focus on oncology, we successfully out-licensed KOS-2187 and our motilin receptor agonist programme to Pfizer, a company with a strong gastrointestinal capability that could best exploit its therapeutic and commercial potential. We appreciate Pfizer's commitment to the development and potential commercialisation of this promising prokinetic compound and look forward to its rapid advancement through the clinic."

Motilin, a hormone secreted by the small intestine, stimulates gastrointestinal motility (movement). The activity of motilin is mediated through the G-protein coupled motilin receptor found on smooth muscle cells of the GI tract and elements of the enteric nervous system. The clinical observation that the macrolide antibiotic erythromycin, a motilin receptor agonist, accelerates gastric emptying in patients with diabetic gastroparesis (impaired gastric emptying) has resulted in efforts to develop non-antibiotic macrolides (motilides) as prokinetic agents.

PF-04548043 is a potent, selective motilin receptor agonist that is chemically stable and orally bioavailable and lacks antibiotic activity. In preclinical studies, PF-04548043 showed an improved safety profile relative to erythromycin and accelerated gastric emptying, suggesting that it may provide symptom relief in several GI diseases.