Phase Ib/II study combining tosedostat with capecitabine in patients with advanced pancreatic adenocarcinoma

Background: Pancreatic ductal adenocarcinoma (PDAC) is an aggressive malignancy with limited therapeutic options. We evaluated the safety and efficacy of the aminopeptidase inhibitor tosedostat with capecitabine in advanced PDAC. Methods: We conducted a phase Ib/II trial of tosedostat with capecitabine as second-line therapy for advanced PDAC. Planned enrollment was 36 patients. Eligible patients were treated with capecitabine 1,000 mg/m² oral twice-daily days 1–14 and oral tosedostat in a dose de-escalation design on days 1–21 of each 21-day cycle. Primary endpoints were the recommended phase 2 dose (RP2D) and progression-free survival (PFS). Results: Sixteen patients were enrolled. Tosedostat 120 mg oral twice daily with capecitabine 1,000 mg/m² oral twice daily was the RP2D. There was one dose-limiting toxicity (DLT) (grade 3 acute coronary syndrome) during phase Ib. The most common treatment-related adverse events were gastrointestinal (nausea, diarrhea), cardiac [QTc prolongation, decreased ejection fraction (EF)], and fatigue. The median PFS was 7.1 months, and the median treatment failure free survival was 3 months. Eight patients experienced stable disease for greater than 3 months. The study was closed early due to lack of drug availability. Conclusions: Tosedostat with capecitabine displayed tolerable toxicity, and prolonged disease control in a subset of patients. These data encourage further exploration of aminopeptidase inhibitors in pancreatic cancer.