OSI Pharmaceuticals Inc has initiated a Phase II clinical study of OSI-7904L, an investigational anti-cancer drug, in patients with previously untreated advanced gastric cancer. OSI-7904L is a novel member of a well-established class of drugs known as thymidylate synthase (TS) inhibitors.

OSI-7904L is a liposomal formulation of a potent TS inhibitor which is designed to improve activity by changing the drug exposure (pharmacokinetic) profile when compared to its non-liposomal formulation, thereby maintaining active concentrations of drug in the tumor for extended periods of time. OSI-7904L is being developed as a potential next-generation cytotoxic drug and competitor to 5-fluorouracil (5-FU) and capecitabine, two of the leading TS inhibitors currently marketed. Evidence suggests that prolonged infusions of 5-FU are associated with improved activity compared with the normal 5-FU protocol. OSI-7904L is designed to mimic the effects of a long-term infusion with a single dose of the liposomal product.

"The initiation of this Phase II study is based on the successful demonstration of a favorably altered drug exposure profile and the predictable and manageable safety profile seen in the Phase I single-agent study conducted with this agent," stated Nicole Onetto, Executive Vice President and Chief Medical Officer of the Company. "We also saw encouraging preliminary indications of anti-tumor activity in the form of several prolonged disease stabilizations amongst heavily pretreated patients in this Phase I trial."

This multi-center, open-label, non-randomized study is scheduled to enroll approximately 50 patients in Europe and the United States, and is designed to evaluate the efficacy and safety of OSI-7904L in chemotherapy-naive gastric cancer patients. OSI-7904L will be administered to patients at the Phase I recommended dose of 12 mg/m2 every 21 days. The primary endpoint of this trial is response rate.