Multicentre phase II pharmacokinetic and pharmacodynamic study of OSI-7904L in previously untreated patients with advanced gastric or gastroesophageal junction adenocarcinoma

A two-stage Simon design was used to evaluate the response rate of OSI-7904L, a liposome encapsulated thymidylate synthase inhibitor, in advanced gastric and/or gastroesophageal adenocarcinoma (A-G/GEJA), administered intravenously at 12 mg m^-2 over 30 min every 21 days. Fifty patients were treated. Median age was 64 years (range 35-82), 62% were male and 89% had ECOG PS of 0/1. A total of 252 cycles were administered; median of 4 per patient (range 1-21). Twelve patients required dose reductions, mainly for skin toxicity. Investigator assessed response rate was 17.4% (95% CI 7.8-31.4) with one complete and seven partial responses in 46 evaluable patients. Twenty-one patients (42%) had stable disease. Median time to progression and survival were 12.4 and 36.9 weeks, respectively. NCI CTCAE Grade 3/4 neutropenia (14%) and thrombocytopenia (4%) were uncommon. The main G3/4 nonhaematological toxicities were skin-related 22%, stomatitis 14%, fatigue/lethargy 10%, and diarrhea 8%. Pharmacokinetic data showed high interpatient variability. Patients with higher AUC were more likely to experience G3/4 toxicity during cycle 1 while baseline homocysteine did not predict toxicity. Response did not correlate with AUC. Elevations in 2′-dU were observed indicating target inhibition. Analysis of TS genotype, TS protein and expression did not reveal any correlation with outcome. OSI-7904L has activity in A-G/GEJA similar to other active agents and an acceptable safety profile.